Post by volkerboehme on Aug 10, 2008 9:18:24 GMT -5
Propliner flying in the Vintage era.
An extended long hot summer has finally come to a sudden end in England and I have time to think about FS9 related issues again. I realise that this forum is dedicated to the Classic era of aviation, but prompted by a recent thread concerning the default Ford Trimotor, this post meanders along the byways of Vintage era propliner flying, whilst partially solving the problems the earlier thread posed.
The Ford Trimotor is an extended family of aircraft. The one Microsoft chose to model is the 4-AT-E which entered airline service in mid 1929. Sixteen were built for the airlines plus one for the USN and another for the USMC. Several earlier models of the 4-AT were later converted to E standard and at least one 4-AT-E later served with the USAAC.
Microsoft default flight dynamics and panels tend to be poorly researched and poorly implemented. In the case of the default Ford 4-AT-E Trimotor, Microsoft seem to have taken the trouble to obtain a real check list from the EAA, but either did not bother to obtain real engine documentation, or failed to understand it. The 4-AT-E was powered by three Wright J6-9-300 Whirlwind engines. Having failed to research this engine Microsoft limited its power output to 300hp at 2000rpm. It really produced 330hp at 2000rpm.
The reason that Trimotor rpm, rates of climb and service ceiling are all deficient in FS9 is simply that the power produced at full throttle at sea level is 10% deficient.
That particular error is easily fixed.
>
[piston_engine]
power_scalar = 1.1
>
There is no need to add or alter anything else in that section of the aircraft.cfg.
The J6 version of the Wright Whirlwind was 'rated' at 300hp because that was a reasonable approximation of the mean power it could develop at sea level whilst running at less than 2000rpm during the full throttle take off. For the FD to reach rated power output during the take off run, and more during the initial climb, the real maximum must be encoded (using a power scalar since Microsoft got it wrong).
Once power output has been rendered realistic rpm must be restricted to the safe maximum of 2000, especially when descending. It was lawful to cruise a J6 engine continuously at 2000rpm, but far from economical, and not necessarily safe in modern terms. Most operators of the 4-AT-E are likely to have published 1750rpm as the target for economical cruise in their operating manuals and after applying the modification proposed in this post that is what FS9 users should target unless battling significant headwinds.
Because the J6 has a fixed pitch screw a real feed back loop always develops when levelling off after the climb. It may take several minutes to establish level flight at 1750rpm as the screw brakes or accelerates the engine in response to varying drag (IAS) acting on the vintage screw which cannot change pitch to compensate.
The next task is to make the inertia of this flying truck, with a huge pendulum mass balance suspended under each wing, more realistic. Delete the original values and paste the following;
Moments of Inertia
empty_weight_pitch_MOI = 24000
empty_weight_roll_MOI = 100000
empty_weight_yaw_MOI = 110000
empty_weight_coupled_MOI = 0.0
We can see that the two outboard giant pendulums are situated fore/aft nearly abeam CoG. They have little impact on pitch inertia, but they are substantially displaced left/right from CoG. They will resist roll and yaw (changes).
The last edit to the aircraft.cfg worth doing before we run into the law of diminishing returns is to revise the Oswald efficiency in the [airplane_geometry] section. It is worth noticing that Ford took the trouble to mount the outboard engines below the aerofoil so that the ugly turbulence from the uncowled radial engines did not pass above and below the wing across a large part of its area. To one significant figure the Oswald efficiency should be 0.7 not 0.6.
I obviously have no idea what the Trimotor was like to handle in the air, but I regard the handling encoded by Microsoft as childish and intended to deliver an unrealistic video game style challenge that has little to do with flight simulation. High wing aircraft of this era exhibited excess pendulum stability. They were heavy in yaw and roll, which means that they tended to inadequate control authority, but those that achieved series production were not aerodynamically unstable.
These issues can only be rectified and rendered realistic by extensive research followed by rewriting of the air file and I am afraid I don't see it as my job to patch payware to that degree of realism on an unpaid basis. My suggestion is that anyone intending to understand the real world operation of the 4-AT-E in the Vintage era of propliner flying proceeds as follows.
Obtain an air file editor such as Air Ed and use it to delete only REC 404 and REC1101 from the default air file and replace them with REC 404 and REC 1101 from my B247D air file linked to from Calclassic.com but actually within the package here;
library.avsim.net/esearch.php?DLID=62457&Name=&FileName=&Author=&CatID=root
Then edit only the two relevant drag values within the replacement REC 1101 restoring them to those encoded by Microsoft for the 4-AT-E.
Airframe drag should be restored from 44 (B247D) to 117 (AT4E)
Gear drag should be restored to zero from 32, since gear drag is always part of the airframe drag for a Ford Trimotor.
Trimotor handling in the air and on the ground will then be better than I think it was in real life, rather than much worse, and the engine power to lift and drag ratios will have been corrected to something more realistic.
The Microsoft handling notes (ford_trimotor_ref.htm) call for the 4-AT-E to be held on the ground until 65 MIAS and once rotated to be climbed immediately at Vy = 72 MIAS using full throttle throughout. The 4-AT-E will accelerate so fast from 65 MIAS to 72 MIAS that the problem is getting the nose up and trimming to prevent overrun of Vy given the limited control and trim authority.
This will all work 'realistically' once the fixes above have been employed. The aerofoil section encoded in REC 404 by Microsoft is not remotely similar to Geottingen 386 as employed by Ford (and pirated from Fokker). The REC 404 code in my B247D file is a variant of the Clark Y aerofoil which is still not accurate but is much closer to the vintage reality.
Climbing at Vy = 72 MIAS will always correctly restrain the engines to less than 2000rpm. The actual engine rpm achieved during a climb sustaining Vy will depend on altitude, the weather, and how expert the user is at continuously leaning vintage aero engines which lack auto mixture control. In practice unless users are intent on simulating the vintage era role of air mechanic they should turn auto mixture ON in the realism menu as a convenient means of delegating the task to their mechanic in the right hand seat.
The 4-AT-E was certificated for single pilot airline operation provided it was flown solely by visual reference to the surface, but in most cases airlines employed a mechanic to sit in the right hand seat where he could perform the role of pilot's assistant; and of course to perform engine checks and maintenance after every landing. The early and primitive Wright Whirlwind radial engines used in the 4-AT-E needed routine maintenance after every single flight.
In any event pilot flying should concentrate on sustaining Vy = 72 MIAS, searching for and avoiding traffic, and navigating the 4-AT-E by reference to the surface, and not on engine management during the climb. As was usual in the Vintage era important engine gauges for outboard engines are mounted directly on the engines, not in the cockpit anyway. In real life the mechanic might need to wander round the cockpit or into the cabin to read them. He noted the readings down, reported them to the pilot, who could make adjustments himself, or let the mechanic adjust things, but either way the mechanic had to wander aft and from side to side again to see if the applied settings were satisfactory before adjusting again if required.
Microsoft encoded realistic weights for the 4-AT-E but the standard fuel tankage was actually 235 USG rather than 231. 9 passengers and bags were indeed the maximum load with full standard tanks. Maximum seating in the cabin was 12 but each extra passenger loaded requires 30 USG of fuel to be offloaded from the standard tanks before flight. Further internal auxiliary tankage was available in real life for ferrying, but is not worth adding.
There was no maximum landing weight and the idea was to wheel it on at about 65 MIAS. Shade this towards 58 MIAS on a really short runway. A three point, or potentially tailwheel first landing at lower IAS must be avoided. The castoring tailwheel was weak and this was the first version of the Ford Trimotor to have one in place of a more robust skid. The 4-AT-E was also eligible to operate from skis.
As a concession to practical necessity I suggest that anyone who does not have access to a multi throttle yoke to enable realistic ground manoeuvring techniques should alter the tailwheel value in the first line of the contact points from 180 to 60 and then set differential_braking_scale = 0, as I believe the 4-AT-E only had a simple hand brake as replicated in the VC. Remember to taxi at walking pace.
Vintage aircraft like the Trimotor need to flown manually. It has three big pendulums hanging under the wing and they may all fight back when you try to initiate, control or arrest roll and yaw. The trick is to do everything slowly and gently so that the giant pendulum you are flying does not swing all over the place. Mishandling will lead to pendulum motion. The idea is to avoid inducing it, but the revised FD will give you enhanced ability to recover if you mishandle. Be warned these realism edits do not render the Trimotor so tame that it can be flown using an autopilot, nor should they.
Remember to keep the ball centred with rudder whilst entering, and throughout, turns. Restrict bank so that the lower edge of the windscreen is parallel with the horizon; unless you need to turn hard and are prepared to risk mishandling leading to yaw and roll oscillation. Obviously this is easier to monitor from the left hand seat when turning right, but that is why you need a VC to replicate real handling practices and problems. The Junkers Trimotor was affectionately called 'Tante Ju' (Auntie Ju) for a reason. These vintage trimotors are genteel old ladies and do not wish to be hurried.
At this point note that several versions of my B247D FS9 flight dynamics are potentially in circulation with my consent. These differ to optimise integration with different cockpit environments. Do not replace your current B247 FD with those above if you are not flying the B247 from within Dee Waldron's Virtual Cockpit environment.
>
The next step is to remedy the usual errors in Microsoft default panel and VC design so that the user can accomplish with minimum fuss what a real pilot has to accomplish.
NOTE: This has already been done if you want to download it instead:
www.calclassic.com/files/4-AT-E_fix.zip
Open the default 4-AT-E panel.cfg and above the window00 section paste;
*************
[VIEWS]
view_forward_WINDOWS = Trimotor_panel
VIEW_FORWARD_DIR = 10, 0, 0
**************
Now scroll down to the bottom of the panel.cfg and edit the Microsoft encoded SIZE_Y= to say;
SIZE_Y=6144
Those changes correct the errors in the default 2D panel design and allow projection of all your scenery and mesh in true placement and perspective whilst running Cockpit View within MSFS.
>
Now the default Virtual Cockpit View environment has to be fixed.
Open the 4-AT-E aircraft.cfg again and find its [Views] command and edit it to read;
eyepoint = 4.3, -1.05, 3.85
You will then be sitting in your VC nearer to where the real pilot sat in the real cockpit and seeing pretty much what a real pilot saw from the real Trimotor cockpit. Notice that when looking straight ahead in the VC you can now see all the needles on all the relevant gauges, over the relevant gauge ranges, by default. You only need to use a hat switch to search for conflicting traffic, landmarks, and line features on the surface to aid navigation. Anyone who has not done so should assign a joystick button or keyboard press in FS9 which defines 'snap back to default view' so that it is easy to restore after scrolling and panning with a hat switch.
There is no reason to use the 2D cockpit environment when flying the Trimotor after you have fixed it for realistic flight simulation use in VC view, but it will still function better than before anyway.
>
>
The rest of this post is about achieving realistic Vintage era simulation in any relevant aircraft. Almost a much abbreviated 'Propliner Tutorial' for an earlier, simpler and much more dangerous era of commercial aviation.
One of the most important skills that real amateur pilots and Vintage era airline pilots need is the ability to judge height. Height is displacement from the local terrain. Altitude is displacement from sea level. An altimeter can only tell you your height if you are over the ocean.
When flying in the vintage era perfectly ordinary weather that you would not even notice as bad weather when driving a car to the airport becomes a potential killer. Even moderately low visibility can kill you. Vintage era navigation was conducted by reference to the surface. You must fly low enough to see the terrain in enough detail to identify landmarks and to intercept and follow line features.
It is very easy to become over absorbed in the task of maintaining contact with the surface; flying lower and lower as visibility or the cloud base deteriorates. Eventually this will kill you. It is very important to be aware of your height, (not your altitude), so that you can recognise when a low cloud base, or locally reduced visibility has forced you down to an unsafe height. When flying by visual reference to the surface the ability to judge height is essential.
Flight simulation users who intend to simulate vintage era aviation must teach themselves to judge height. Learn to maintain a chosen safe height above the terrain and any construction rising above the terrain as the terrain undulates. Above all recognise when the weather has forced descent to an unsafe height.
The problem within MSFS is that many cockpit environments, including many Microsoft default cockpit environments, have been designed to distort and misplace the scenery and mesh using fake SIZE_Y values and / or fake ZOOM values. In order to judge either height, or distance to go, fight simulator users need realistic scenery placement, perspective and zoom.
After ensuring that you are using any FS9 VC with 'realistic' eyepoint or a 2D panel with SIZE_Y = 6K and ZOOM = 1 plus an encoded and 'realistic' VIEW_FORWARD_DIR = command teach yourself to recognise a height (not altitude) of 1500 feet. The 'fixed' default Ford Trimotor will do nicely. Take off from any airfield near a city which is situated on a plain or plateau where terrain elevation changes very little. Note the altitude of the runway. If it is 2000 feet QNH then climb to 3500 QNH so that your height is 1500 feet (QFE) above the airfield. Fly backwards and forwards across the airfield, the suburbs and the city centre. Teach yourself to recognise what the various autogen buildings and trees you have personally chosen to install look like from a height of 1500 feet.
This is important because you must be able to recognise when you are unable to maintain a height of 1500 feet whilst identifying landmarks and following line features during VFR navigation, due to low cloud base or reduced visibility. As soon as you are forced below a height of 1500 feet the weather has become too dangerous to continue and you must divert. Potentially back to your point of departure. The ability to recognise and maintain a height of 1500 feet only comes with experience. Practice, practice, practice. I have specific reasons for suggesting 1500 feet as minimum cruising height (not altitude), but they do not really matter.
Once you have done all the above and are in the air over a city in the 'fixed' FS9 default Ford Trimotor level off about 1500 feet above the terrain, or tops of any nearby buildings, with 3 x 1750 rpm applied. Now employ the user defined weather menu to turn the visibility down to 3 miles. Notice that you can still locate and follow any rivers, roads and railway lines inside the limit of restricted visibility by looking through the windscreen.
Flying the Trimotor or other vintage aircraft in FS9 should not be about fighting childish video game aircraft instability. It should be all about learning to navigate by visual reference to the surface using any tourist road map, or preferably a tourist map that also shows railway lines, railway stations, and airport locations.
During flight simulation of the Vintage era the goal is to recognise landmarks chosen from a tourist map, then track from them to intercept a line feature, shown on the map, but not yet in view. Tracking from a landmark to a another landmark already in view is good practice, but attempting to track directly to a landmark not yet in view should be avoided.
By default the aircraft is always flown to the right of the on course track. Pilot flying eventually locates the chosen line feature, crosses over it, turns left, and follows it keeping it on the left. Other aircraft following the line feature in the opposite direction will be doing the same and will pass 'port to port' as required by maritime law, which applies to all vessels in transit including aircraft. If you ever meet a head on confliction you must (both) break right.
Follow that intercepted line feature to the next landmark which you chose as a waypoint when preparing your VFR flight plan from a tourist map. Now set off to intercept another line feature that you will be able to recognise when it looms into view. Repeat as often as necessary.
Once flight simulation is conducted in realistically restricted visibility attempts to locate landmarks directly will often fail because they pass by to one side, outside the restricted limit of visibility. Cultivate the habit of navigating along line features to landmarks which you will use as waypoints (turning points). Then turn for another line feature which you are certain to intercept and can follow to the next landmark (waypoint).
Line features are rarely straight. Coasts, lake shores, rivers, canals, roads and railways are all line features and the landmarks chosen as waypoints will often be nothing more than the conjunction of two such recognisable line features. The landmark (waypoint) itself is located by turning left to follow the intercepted line feature upon which it lays, from somewhere / anywhere to the right of the landmark, to the landmark. Sometimes a landmark (turning point) is just a sharp and recognisable bend in the feature you are following
As soon as visibility is too poor to see one landmark from the last it is an error to set off directly to the next landmark, and therefore an error to choose landmarks during flight planning that cannot be located by intercepting an extended line feature leading to the next landmark. Remember visibility may reduce during the flight.
The idea is to give yourself an entire line feature to locate after setting of from any waypoint. You aim right of the next landmark, so that you know you must turn left when you locate the line feature that leads to it. Each vintage era flight is a series of time wasting turn slightly right, turn hard left, zig-zags.
Practice intercepting all sorts of line features right of the target waypoint and turning left from the interception point, following the line feature to the target, keeping the line feature on your left. Big rivers and big lake shores make excellent line features. Roads and railways are more common but may be more difficult to differentiate from one another. A key skill as you cruise along is working out the track of every line feature you cross. Often you will be tracking north looking for a road or railway whose general track is SE to NW before turning NW to follow it. Learn to recognise the magnetic track of line features not just when you are tracking 360, 090, 180 or 270 but when the plan calls for you to track say 040 to the line feature. Always be thinking about the *relative* track of the feature you are trying to locate. The relative track may be the only thing recognisable about it in restricted visibility.
After you turn to follow what you believe to be the correct line feature, every few minutes check your compass heading against the magnetic track of the feature you are following. Is it compatible with the line feature you intended to follow? You will sometimes intercept the wrong line feature.
For that reason always start a stop watch when turning onto any leg of any flight plan. You must always know how long you have been flying in the wrong direction so that you can 180 and backtrack along the leg for the same amount of time to get back to where you made the error and then resume the flight plan track from the position of the original mistake to the feature you really need to intercept.
This technique also applies to sea crossings, but commercial ocean crossings were not attempted until Classic era techniques were available. If you are tasked to fly from London to Antwerp then you must be sure to intercept the coast of Europe to the right of the Schelde estuary so that you know that you have to turn left on intercepting the coast. When the (French or Belgian) coast is located pilot flying crosses the coast to fly just inland with the coast left of the nose and follows it northward and then inland to Antwerp along the southern shore of the Schelde estuary.
It may seem that there is no need to have any waypoints before the French/Belgian coast. Wrong. Remember you must be able to divert back to your point of departure at any time before the point of no return. You must have a (potentially second) flightplan with line features and landmarks to allow that. Think about how much harder that makes flight planning in the Vintage era versus turning round and just following the same radio beams back the way you came in the Classic era.
During Vintage era flight the cardinal sin is to fail to aim far enough to the right of the next landmark when seeking the line feature that leads to it. If you fail to aim far enough to the right you may not allow for an unexpected crosswind from the right on that leg. Such a crosswind could drift you left of the next landmark. In those circumstances you are doomed to turn left away from the landmark when you reach the line feature. You will progress further and further away from the landmark, potentially flying into high unexpected terrain.
The concept of 'dead reckoning' is only relevant to Vintage era simulation in so far as it relates to ensuring that you locate the line feature to the right of the next landmark (waypoint).
This was the fatal problem. In the Vintage era aircrew needed to aim well right of the next waypoint whilst seeking the next line feature to follow. During that phase they sometimes drifted far right of track and flew into high terrain when a cross wind developed from the left. But before adoption of the techniques that marked the arrival of the Classic era there was no safer choice. Many pilots who attempted to fly direct to unseen landmarks never saw them go by, to left or right, beyond the limit of their current visibility and became lost. Without the possibility of help from air traffic control they failed to find an airfield large enough to land on before they ran out of fuel. Others wandered into high terrain whilst 'square searching' for the landmark they eventually realised they had overshot
Pilots are allowed to cut corners when following line features, but not to the extent that they might collide with an aircraft keeping the same line feature on its left coming in the opposite direction. Pilots must keep right of the median. Often a road and a railway will follow a river through a river valley. Do not become absorbed in following just one of the line features. A road may cross the median of the valley via a bridge. The aircraft must be flown to the right of the median.
During Vintage era planning common sense must however prevail. You must always fly right of track when *following* a line feature without exception. By default you will plan to fly right of track when *searching* for the next line feature, but not when it defies common sense. Suppose you are tasked to fly from Green Bay (Wisconsin) across Lake Michigan to Grand Rapids. It would be ludicrous to fly southward down the lake to intercept the east shore south of Muskegon.
In a Trimotor, which can just about stagger along and keep flying with 66% max safe power applied after losing one engine, you plan to fly directly east from Green Bay to intercept the east shore left of Muskegon. When you locate the east shore you turn right keeping the shore on your left. You follow it to Muskegon. Over Muskegon you turn to locate the major road that runs from Muskegon to Grand Rapids and you simply follow it keeping it on your left. You could go down to Spring Lake and follow it to Grand Rapids, but you would have to keep it on your left and the river that flows through Grand Rapids into Spring Lake is pretty small and may be more difficult to follow than the main road. Yes, the current main road is bigger and better than it was in 1929, but there was a road to follow even in 1929.
During Vintage era navigation there are legs whilst searching for a line feature in limited visibility when you have only an approximate idea of where you are now, or where exactly you will encounter the next flight plan line feature, but you always know exactly what you are looking for through the windscreen, and which way you will turn when you locate it. In low visibility you may locate it very suddenly and may need to turn quickly to keep it in view on your left.
Unless in significant turbulence the challenge of operating vintage aircraft should be navigating the aircraft lawfully and safely without any electronic aids, not flying it. Eventually learn to cope with navigation in 3 miles visibility at dawn and dusk with the sun in any direction. Then learn to do it with rain or snow showers from time to time, employing the user defined weather menu to control the difficulty of the challenge as experience is gained. Don't start with 3 miles. Work your way down from say 10 or even 20 miles visibility flying the same route several times until you can navigate it safely in a visibility of 3 miles. Spend a long time training at 5 miles before attempting 3. In any visibility practice maintaining a more or less constant height of 1500 feet, varying your altitude as required, and navigate solely by visual reference to the surface.
You will notice that 3D scenery looks more and more realistic as the visibility reduces and blurs any imperfections
Real commercial pilots attempting navigation by visual reference to the surface need to see (from a height of 1500 feet) what is just ahead on the ground in restricted visibility at all times and aircraft intended for flight simulation use must deliver that possibility. Ten versions of MSFS after purchasing the code from Bruce Artwick (including CFS versions) Microsoft still don't get it. Their excuses for solutions to badly designed default aircraft are pathetic and are no substitute for properly designed cockpit environments that do not require the scenery and mesh to be projected with inaccurate placement, zoom and perspective.
A visibility of 3 miles is, in many current jurisdictions, nothing more than the lower limit of visibility that newly qualified amateur pilots are expected to cope with, without access to any electronic aids. Vintage era simulation is all about developing that real world skill. Only after experiencing rising terrain or masts looming into view frighteningly close ahead is it possible to understand why vintage airliners had to be so slow. This is stuff that cannot be understood by reading a book. It has to be 'experienced'. That is what flight simulators are for.
Road maps that show coasts, lakes, rivers and roads are available for purchase everywhere. Many also show current public use airfields for the benefit of tourists who may need to locate them to access airline services. Road Atlases such as that prepared by Rand McNally are perfectly adequate for simulated vintage era navigation right across the United States and in practice just about good enough for simulated vintage era navigation across Puerto Rico, Canada and Mexico as well. You will just have a few more roads to confuse you, or to follow, and more masts to threaten you in the modern world. Unfortunately Rand McNally does not show railways. Seek out similar volumes for other continents and unlimited world wide realistic challenges wait. There is no need for third parties to create or define them for FS9 users and to simulate Vintage era navigation you do not need current Sectional and terminal charts. They should be employed when simulating the current era.
The airline pilots of 1929 had to push their luck a lot further than flying in a visibility of three miles if they wanted to keep their jobs, often with fatal consequences for all aboard. Simulating what they had to do to keep their jobs is the only way to understand why the vintage era of aviation killed so many aircrew and passengers and why the classic era techniques had to be imposed by federal regulation. I am aware that there was much more to learn before conducting VFR navigation in the real vintage era. This post is intended to help those with no aircrew experience to grasp the main differences between Vintage and Classic era airline flying and why one had to be relinquished in favour of the other.
Classic era flying was all about flying safely at high level using avionics, radio navigation charts and detailed IFR procedures, imposed by ATC. Those new skills were acquired whilst qualifying for the new Instrument Rating, first introduced in 1932, and that soon became a de facto or federal employment requirement for airline pilots everywhere. Classic era IFR flying can be conducted at much higher cruising velocities, travelling in straight lines directly from waypoint to waypoint, and is much, much safer for all concerned. The only way to discover for yourself why it is so superior to the Vintage era methods is to attempt to navigate the Vintage era way, in moderately low visibility that would not even be recognisable as limited visibility when driving along an urban road.
Finally bear in mind that in the modern world there are all kinds of rules that did not exist in the Vintage era. This post is explicitly about the Vintage era and is not intended to replace VFR navigation techniques being taught to real aircrew today in accordance with current requirements. Real aircrew must stick with the techniques they were taught and should make the maximum use of modern electronic aids and modern ATC to maximise safety at all times. This post is about how things worked (in general) before those possibilities existed.
FSAviator 11/06
An extended long hot summer has finally come to a sudden end in England and I have time to think about FS9 related issues again. I realise that this forum is dedicated to the Classic era of aviation, but prompted by a recent thread concerning the default Ford Trimotor, this post meanders along the byways of Vintage era propliner flying, whilst partially solving the problems the earlier thread posed.
The Ford Trimotor is an extended family of aircraft. The one Microsoft chose to model is the 4-AT-E which entered airline service in mid 1929. Sixteen were built for the airlines plus one for the USN and another for the USMC. Several earlier models of the 4-AT were later converted to E standard and at least one 4-AT-E later served with the USAAC.
Microsoft default flight dynamics and panels tend to be poorly researched and poorly implemented. In the case of the default Ford 4-AT-E Trimotor, Microsoft seem to have taken the trouble to obtain a real check list from the EAA, but either did not bother to obtain real engine documentation, or failed to understand it. The 4-AT-E was powered by three Wright J6-9-300 Whirlwind engines. Having failed to research this engine Microsoft limited its power output to 300hp at 2000rpm. It really produced 330hp at 2000rpm.
The reason that Trimotor rpm, rates of climb and service ceiling are all deficient in FS9 is simply that the power produced at full throttle at sea level is 10% deficient.
That particular error is easily fixed.
>
[piston_engine]
power_scalar = 1.1
>
There is no need to add or alter anything else in that section of the aircraft.cfg.
The J6 version of the Wright Whirlwind was 'rated' at 300hp because that was a reasonable approximation of the mean power it could develop at sea level whilst running at less than 2000rpm during the full throttle take off. For the FD to reach rated power output during the take off run, and more during the initial climb, the real maximum must be encoded (using a power scalar since Microsoft got it wrong).
Once power output has been rendered realistic rpm must be restricted to the safe maximum of 2000, especially when descending. It was lawful to cruise a J6 engine continuously at 2000rpm, but far from economical, and not necessarily safe in modern terms. Most operators of the 4-AT-E are likely to have published 1750rpm as the target for economical cruise in their operating manuals and after applying the modification proposed in this post that is what FS9 users should target unless battling significant headwinds.
Because the J6 has a fixed pitch screw a real feed back loop always develops when levelling off after the climb. It may take several minutes to establish level flight at 1750rpm as the screw brakes or accelerates the engine in response to varying drag (IAS) acting on the vintage screw which cannot change pitch to compensate.
The next task is to make the inertia of this flying truck, with a huge pendulum mass balance suspended under each wing, more realistic. Delete the original values and paste the following;
Moments of Inertia
empty_weight_pitch_MOI = 24000
empty_weight_roll_MOI = 100000
empty_weight_yaw_MOI = 110000
empty_weight_coupled_MOI = 0.0
We can see that the two outboard giant pendulums are situated fore/aft nearly abeam CoG. They have little impact on pitch inertia, but they are substantially displaced left/right from CoG. They will resist roll and yaw (changes).
The last edit to the aircraft.cfg worth doing before we run into the law of diminishing returns is to revise the Oswald efficiency in the [airplane_geometry] section. It is worth noticing that Ford took the trouble to mount the outboard engines below the aerofoil so that the ugly turbulence from the uncowled radial engines did not pass above and below the wing across a large part of its area. To one significant figure the Oswald efficiency should be 0.7 not 0.6.
I obviously have no idea what the Trimotor was like to handle in the air, but I regard the handling encoded by Microsoft as childish and intended to deliver an unrealistic video game style challenge that has little to do with flight simulation. High wing aircraft of this era exhibited excess pendulum stability. They were heavy in yaw and roll, which means that they tended to inadequate control authority, but those that achieved series production were not aerodynamically unstable.
These issues can only be rectified and rendered realistic by extensive research followed by rewriting of the air file and I am afraid I don't see it as my job to patch payware to that degree of realism on an unpaid basis. My suggestion is that anyone intending to understand the real world operation of the 4-AT-E in the Vintage era of propliner flying proceeds as follows.
Obtain an air file editor such as Air Ed and use it to delete only REC 404 and REC1101 from the default air file and replace them with REC 404 and REC 1101 from my B247D air file linked to from Calclassic.com but actually within the package here;
library.avsim.net/esearch.php?DLID=62457&Name=&FileName=&Author=&CatID=root
Then edit only the two relevant drag values within the replacement REC 1101 restoring them to those encoded by Microsoft for the 4-AT-E.
Airframe drag should be restored from 44 (B247D) to 117 (AT4E)
Gear drag should be restored to zero from 32, since gear drag is always part of the airframe drag for a Ford Trimotor.
Trimotor handling in the air and on the ground will then be better than I think it was in real life, rather than much worse, and the engine power to lift and drag ratios will have been corrected to something more realistic.
The Microsoft handling notes (ford_trimotor_ref.htm) call for the 4-AT-E to be held on the ground until 65 MIAS and once rotated to be climbed immediately at Vy = 72 MIAS using full throttle throughout. The 4-AT-E will accelerate so fast from 65 MIAS to 72 MIAS that the problem is getting the nose up and trimming to prevent overrun of Vy given the limited control and trim authority.
This will all work 'realistically' once the fixes above have been employed. The aerofoil section encoded in REC 404 by Microsoft is not remotely similar to Geottingen 386 as employed by Ford (and pirated from Fokker). The REC 404 code in my B247D file is a variant of the Clark Y aerofoil which is still not accurate but is much closer to the vintage reality.
Climbing at Vy = 72 MIAS will always correctly restrain the engines to less than 2000rpm. The actual engine rpm achieved during a climb sustaining Vy will depend on altitude, the weather, and how expert the user is at continuously leaning vintage aero engines which lack auto mixture control. In practice unless users are intent on simulating the vintage era role of air mechanic they should turn auto mixture ON in the realism menu as a convenient means of delegating the task to their mechanic in the right hand seat.
The 4-AT-E was certificated for single pilot airline operation provided it was flown solely by visual reference to the surface, but in most cases airlines employed a mechanic to sit in the right hand seat where he could perform the role of pilot's assistant; and of course to perform engine checks and maintenance after every landing. The early and primitive Wright Whirlwind radial engines used in the 4-AT-E needed routine maintenance after every single flight.
In any event pilot flying should concentrate on sustaining Vy = 72 MIAS, searching for and avoiding traffic, and navigating the 4-AT-E by reference to the surface, and not on engine management during the climb. As was usual in the Vintage era important engine gauges for outboard engines are mounted directly on the engines, not in the cockpit anyway. In real life the mechanic might need to wander round the cockpit or into the cabin to read them. He noted the readings down, reported them to the pilot, who could make adjustments himself, or let the mechanic adjust things, but either way the mechanic had to wander aft and from side to side again to see if the applied settings were satisfactory before adjusting again if required.
Microsoft encoded realistic weights for the 4-AT-E but the standard fuel tankage was actually 235 USG rather than 231. 9 passengers and bags were indeed the maximum load with full standard tanks. Maximum seating in the cabin was 12 but each extra passenger loaded requires 30 USG of fuel to be offloaded from the standard tanks before flight. Further internal auxiliary tankage was available in real life for ferrying, but is not worth adding.
There was no maximum landing weight and the idea was to wheel it on at about 65 MIAS. Shade this towards 58 MIAS on a really short runway. A three point, or potentially tailwheel first landing at lower IAS must be avoided. The castoring tailwheel was weak and this was the first version of the Ford Trimotor to have one in place of a more robust skid. The 4-AT-E was also eligible to operate from skis.
As a concession to practical necessity I suggest that anyone who does not have access to a multi throttle yoke to enable realistic ground manoeuvring techniques should alter the tailwheel value in the first line of the contact points from 180 to 60 and then set differential_braking_scale = 0, as I believe the 4-AT-E only had a simple hand brake as replicated in the VC. Remember to taxi at walking pace.
Vintage aircraft like the Trimotor need to flown manually. It has three big pendulums hanging under the wing and they may all fight back when you try to initiate, control or arrest roll and yaw. The trick is to do everything slowly and gently so that the giant pendulum you are flying does not swing all over the place. Mishandling will lead to pendulum motion. The idea is to avoid inducing it, but the revised FD will give you enhanced ability to recover if you mishandle. Be warned these realism edits do not render the Trimotor so tame that it can be flown using an autopilot, nor should they.
Remember to keep the ball centred with rudder whilst entering, and throughout, turns. Restrict bank so that the lower edge of the windscreen is parallel with the horizon; unless you need to turn hard and are prepared to risk mishandling leading to yaw and roll oscillation. Obviously this is easier to monitor from the left hand seat when turning right, but that is why you need a VC to replicate real handling practices and problems. The Junkers Trimotor was affectionately called 'Tante Ju' (Auntie Ju) for a reason. These vintage trimotors are genteel old ladies and do not wish to be hurried.
At this point note that several versions of my B247D FS9 flight dynamics are potentially in circulation with my consent. These differ to optimise integration with different cockpit environments. Do not replace your current B247 FD with those above if you are not flying the B247 from within Dee Waldron's Virtual Cockpit environment.
>
The next step is to remedy the usual errors in Microsoft default panel and VC design so that the user can accomplish with minimum fuss what a real pilot has to accomplish.
NOTE: This has already been done if you want to download it instead:
www.calclassic.com/files/4-AT-E_fix.zip
Open the default 4-AT-E panel.cfg and above the window00 section paste;
*************
[VIEWS]
view_forward_WINDOWS = Trimotor_panel
VIEW_FORWARD_DIR = 10, 0, 0
**************
Now scroll down to the bottom of the panel.cfg and edit the Microsoft encoded SIZE_Y= to say;
SIZE_Y=6144
Those changes correct the errors in the default 2D panel design and allow projection of all your scenery and mesh in true placement and perspective whilst running Cockpit View within MSFS.
>
Now the default Virtual Cockpit View environment has to be fixed.
Open the 4-AT-E aircraft.cfg again and find its [Views] command and edit it to read;
eyepoint = 4.3, -1.05, 3.85
You will then be sitting in your VC nearer to where the real pilot sat in the real cockpit and seeing pretty much what a real pilot saw from the real Trimotor cockpit. Notice that when looking straight ahead in the VC you can now see all the needles on all the relevant gauges, over the relevant gauge ranges, by default. You only need to use a hat switch to search for conflicting traffic, landmarks, and line features on the surface to aid navigation. Anyone who has not done so should assign a joystick button or keyboard press in FS9 which defines 'snap back to default view' so that it is easy to restore after scrolling and panning with a hat switch.
There is no reason to use the 2D cockpit environment when flying the Trimotor after you have fixed it for realistic flight simulation use in VC view, but it will still function better than before anyway.
>
>
The rest of this post is about achieving realistic Vintage era simulation in any relevant aircraft. Almost a much abbreviated 'Propliner Tutorial' for an earlier, simpler and much more dangerous era of commercial aviation.
One of the most important skills that real amateur pilots and Vintage era airline pilots need is the ability to judge height. Height is displacement from the local terrain. Altitude is displacement from sea level. An altimeter can only tell you your height if you are over the ocean.
When flying in the vintage era perfectly ordinary weather that you would not even notice as bad weather when driving a car to the airport becomes a potential killer. Even moderately low visibility can kill you. Vintage era navigation was conducted by reference to the surface. You must fly low enough to see the terrain in enough detail to identify landmarks and to intercept and follow line features.
It is very easy to become over absorbed in the task of maintaining contact with the surface; flying lower and lower as visibility or the cloud base deteriorates. Eventually this will kill you. It is very important to be aware of your height, (not your altitude), so that you can recognise when a low cloud base, or locally reduced visibility has forced you down to an unsafe height. When flying by visual reference to the surface the ability to judge height is essential.
Flight simulation users who intend to simulate vintage era aviation must teach themselves to judge height. Learn to maintain a chosen safe height above the terrain and any construction rising above the terrain as the terrain undulates. Above all recognise when the weather has forced descent to an unsafe height.
The problem within MSFS is that many cockpit environments, including many Microsoft default cockpit environments, have been designed to distort and misplace the scenery and mesh using fake SIZE_Y values and / or fake ZOOM values. In order to judge either height, or distance to go, fight simulator users need realistic scenery placement, perspective and zoom.
After ensuring that you are using any FS9 VC with 'realistic' eyepoint or a 2D panel with SIZE_Y = 6K and ZOOM = 1 plus an encoded and 'realistic' VIEW_FORWARD_DIR = command teach yourself to recognise a height (not altitude) of 1500 feet. The 'fixed' default Ford Trimotor will do nicely. Take off from any airfield near a city which is situated on a plain or plateau where terrain elevation changes very little. Note the altitude of the runway. If it is 2000 feet QNH then climb to 3500 QNH so that your height is 1500 feet (QFE) above the airfield. Fly backwards and forwards across the airfield, the suburbs and the city centre. Teach yourself to recognise what the various autogen buildings and trees you have personally chosen to install look like from a height of 1500 feet.
This is important because you must be able to recognise when you are unable to maintain a height of 1500 feet whilst identifying landmarks and following line features during VFR navigation, due to low cloud base or reduced visibility. As soon as you are forced below a height of 1500 feet the weather has become too dangerous to continue and you must divert. Potentially back to your point of departure. The ability to recognise and maintain a height of 1500 feet only comes with experience. Practice, practice, practice. I have specific reasons for suggesting 1500 feet as minimum cruising height (not altitude), but they do not really matter.
Once you have done all the above and are in the air over a city in the 'fixed' FS9 default Ford Trimotor level off about 1500 feet above the terrain, or tops of any nearby buildings, with 3 x 1750 rpm applied. Now employ the user defined weather menu to turn the visibility down to 3 miles. Notice that you can still locate and follow any rivers, roads and railway lines inside the limit of restricted visibility by looking through the windscreen.
Flying the Trimotor or other vintage aircraft in FS9 should not be about fighting childish video game aircraft instability. It should be all about learning to navigate by visual reference to the surface using any tourist road map, or preferably a tourist map that also shows railway lines, railway stations, and airport locations.
During flight simulation of the Vintage era the goal is to recognise landmarks chosen from a tourist map, then track from them to intercept a line feature, shown on the map, but not yet in view. Tracking from a landmark to a another landmark already in view is good practice, but attempting to track directly to a landmark not yet in view should be avoided.
By default the aircraft is always flown to the right of the on course track. Pilot flying eventually locates the chosen line feature, crosses over it, turns left, and follows it keeping it on the left. Other aircraft following the line feature in the opposite direction will be doing the same and will pass 'port to port' as required by maritime law, which applies to all vessels in transit including aircraft. If you ever meet a head on confliction you must (both) break right.
Follow that intercepted line feature to the next landmark which you chose as a waypoint when preparing your VFR flight plan from a tourist map. Now set off to intercept another line feature that you will be able to recognise when it looms into view. Repeat as often as necessary.
Once flight simulation is conducted in realistically restricted visibility attempts to locate landmarks directly will often fail because they pass by to one side, outside the restricted limit of visibility. Cultivate the habit of navigating along line features to landmarks which you will use as waypoints (turning points). Then turn for another line feature which you are certain to intercept and can follow to the next landmark (waypoint).
Line features are rarely straight. Coasts, lake shores, rivers, canals, roads and railways are all line features and the landmarks chosen as waypoints will often be nothing more than the conjunction of two such recognisable line features. The landmark (waypoint) itself is located by turning left to follow the intercepted line feature upon which it lays, from somewhere / anywhere to the right of the landmark, to the landmark. Sometimes a landmark (turning point) is just a sharp and recognisable bend in the feature you are following
As soon as visibility is too poor to see one landmark from the last it is an error to set off directly to the next landmark, and therefore an error to choose landmarks during flight planning that cannot be located by intercepting an extended line feature leading to the next landmark. Remember visibility may reduce during the flight.
The idea is to give yourself an entire line feature to locate after setting of from any waypoint. You aim right of the next landmark, so that you know you must turn left when you locate the line feature that leads to it. Each vintage era flight is a series of time wasting turn slightly right, turn hard left, zig-zags.
Practice intercepting all sorts of line features right of the target waypoint and turning left from the interception point, following the line feature to the target, keeping the line feature on your left. Big rivers and big lake shores make excellent line features. Roads and railways are more common but may be more difficult to differentiate from one another. A key skill as you cruise along is working out the track of every line feature you cross. Often you will be tracking north looking for a road or railway whose general track is SE to NW before turning NW to follow it. Learn to recognise the magnetic track of line features not just when you are tracking 360, 090, 180 or 270 but when the plan calls for you to track say 040 to the line feature. Always be thinking about the *relative* track of the feature you are trying to locate. The relative track may be the only thing recognisable about it in restricted visibility.
After you turn to follow what you believe to be the correct line feature, every few minutes check your compass heading against the magnetic track of the feature you are following. Is it compatible with the line feature you intended to follow? You will sometimes intercept the wrong line feature.
For that reason always start a stop watch when turning onto any leg of any flight plan. You must always know how long you have been flying in the wrong direction so that you can 180 and backtrack along the leg for the same amount of time to get back to where you made the error and then resume the flight plan track from the position of the original mistake to the feature you really need to intercept.
This technique also applies to sea crossings, but commercial ocean crossings were not attempted until Classic era techniques were available. If you are tasked to fly from London to Antwerp then you must be sure to intercept the coast of Europe to the right of the Schelde estuary so that you know that you have to turn left on intercepting the coast. When the (French or Belgian) coast is located pilot flying crosses the coast to fly just inland with the coast left of the nose and follows it northward and then inland to Antwerp along the southern shore of the Schelde estuary.
It may seem that there is no need to have any waypoints before the French/Belgian coast. Wrong. Remember you must be able to divert back to your point of departure at any time before the point of no return. You must have a (potentially second) flightplan with line features and landmarks to allow that. Think about how much harder that makes flight planning in the Vintage era versus turning round and just following the same radio beams back the way you came in the Classic era.
During Vintage era flight the cardinal sin is to fail to aim far enough to the right of the next landmark when seeking the line feature that leads to it. If you fail to aim far enough to the right you may not allow for an unexpected crosswind from the right on that leg. Such a crosswind could drift you left of the next landmark. In those circumstances you are doomed to turn left away from the landmark when you reach the line feature. You will progress further and further away from the landmark, potentially flying into high unexpected terrain.
The concept of 'dead reckoning' is only relevant to Vintage era simulation in so far as it relates to ensuring that you locate the line feature to the right of the next landmark (waypoint).
This was the fatal problem. In the Vintage era aircrew needed to aim well right of the next waypoint whilst seeking the next line feature to follow. During that phase they sometimes drifted far right of track and flew into high terrain when a cross wind developed from the left. But before adoption of the techniques that marked the arrival of the Classic era there was no safer choice. Many pilots who attempted to fly direct to unseen landmarks never saw them go by, to left or right, beyond the limit of their current visibility and became lost. Without the possibility of help from air traffic control they failed to find an airfield large enough to land on before they ran out of fuel. Others wandered into high terrain whilst 'square searching' for the landmark they eventually realised they had overshot
Pilots are allowed to cut corners when following line features, but not to the extent that they might collide with an aircraft keeping the same line feature on its left coming in the opposite direction. Pilots must keep right of the median. Often a road and a railway will follow a river through a river valley. Do not become absorbed in following just one of the line features. A road may cross the median of the valley via a bridge. The aircraft must be flown to the right of the median.
During Vintage era planning common sense must however prevail. You must always fly right of track when *following* a line feature without exception. By default you will plan to fly right of track when *searching* for the next line feature, but not when it defies common sense. Suppose you are tasked to fly from Green Bay (Wisconsin) across Lake Michigan to Grand Rapids. It would be ludicrous to fly southward down the lake to intercept the east shore south of Muskegon.
In a Trimotor, which can just about stagger along and keep flying with 66% max safe power applied after losing one engine, you plan to fly directly east from Green Bay to intercept the east shore left of Muskegon. When you locate the east shore you turn right keeping the shore on your left. You follow it to Muskegon. Over Muskegon you turn to locate the major road that runs from Muskegon to Grand Rapids and you simply follow it keeping it on your left. You could go down to Spring Lake and follow it to Grand Rapids, but you would have to keep it on your left and the river that flows through Grand Rapids into Spring Lake is pretty small and may be more difficult to follow than the main road. Yes, the current main road is bigger and better than it was in 1929, but there was a road to follow even in 1929.
During Vintage era navigation there are legs whilst searching for a line feature in limited visibility when you have only an approximate idea of where you are now, or where exactly you will encounter the next flight plan line feature, but you always know exactly what you are looking for through the windscreen, and which way you will turn when you locate it. In low visibility you may locate it very suddenly and may need to turn quickly to keep it in view on your left.
Unless in significant turbulence the challenge of operating vintage aircraft should be navigating the aircraft lawfully and safely without any electronic aids, not flying it. Eventually learn to cope with navigation in 3 miles visibility at dawn and dusk with the sun in any direction. Then learn to do it with rain or snow showers from time to time, employing the user defined weather menu to control the difficulty of the challenge as experience is gained. Don't start with 3 miles. Work your way down from say 10 or even 20 miles visibility flying the same route several times until you can navigate it safely in a visibility of 3 miles. Spend a long time training at 5 miles before attempting 3. In any visibility practice maintaining a more or less constant height of 1500 feet, varying your altitude as required, and navigate solely by visual reference to the surface.
You will notice that 3D scenery looks more and more realistic as the visibility reduces and blurs any imperfections
Real commercial pilots attempting navigation by visual reference to the surface need to see (from a height of 1500 feet) what is just ahead on the ground in restricted visibility at all times and aircraft intended for flight simulation use must deliver that possibility. Ten versions of MSFS after purchasing the code from Bruce Artwick (including CFS versions) Microsoft still don't get it. Their excuses for solutions to badly designed default aircraft are pathetic and are no substitute for properly designed cockpit environments that do not require the scenery and mesh to be projected with inaccurate placement, zoom and perspective.
A visibility of 3 miles is, in many current jurisdictions, nothing more than the lower limit of visibility that newly qualified amateur pilots are expected to cope with, without access to any electronic aids. Vintage era simulation is all about developing that real world skill. Only after experiencing rising terrain or masts looming into view frighteningly close ahead is it possible to understand why vintage airliners had to be so slow. This is stuff that cannot be understood by reading a book. It has to be 'experienced'. That is what flight simulators are for.
Road maps that show coasts, lakes, rivers and roads are available for purchase everywhere. Many also show current public use airfields for the benefit of tourists who may need to locate them to access airline services. Road Atlases such as that prepared by Rand McNally are perfectly adequate for simulated vintage era navigation right across the United States and in practice just about good enough for simulated vintage era navigation across Puerto Rico, Canada and Mexico as well. You will just have a few more roads to confuse you, or to follow, and more masts to threaten you in the modern world. Unfortunately Rand McNally does not show railways. Seek out similar volumes for other continents and unlimited world wide realistic challenges wait. There is no need for third parties to create or define them for FS9 users and to simulate Vintage era navigation you do not need current Sectional and terminal charts. They should be employed when simulating the current era.
The airline pilots of 1929 had to push their luck a lot further than flying in a visibility of three miles if they wanted to keep their jobs, often with fatal consequences for all aboard. Simulating what they had to do to keep their jobs is the only way to understand why the vintage era of aviation killed so many aircrew and passengers and why the classic era techniques had to be imposed by federal regulation. I am aware that there was much more to learn before conducting VFR navigation in the real vintage era. This post is intended to help those with no aircrew experience to grasp the main differences between Vintage and Classic era airline flying and why one had to be relinquished in favour of the other.
Classic era flying was all about flying safely at high level using avionics, radio navigation charts and detailed IFR procedures, imposed by ATC. Those new skills were acquired whilst qualifying for the new Instrument Rating, first introduced in 1932, and that soon became a de facto or federal employment requirement for airline pilots everywhere. Classic era IFR flying can be conducted at much higher cruising velocities, travelling in straight lines directly from waypoint to waypoint, and is much, much safer for all concerned. The only way to discover for yourself why it is so superior to the Vintage era methods is to attempt to navigate the Vintage era way, in moderately low visibility that would not even be recognisable as limited visibility when driving along an urban road.
Finally bear in mind that in the modern world there are all kinds of rules that did not exist in the Vintage era. This post is explicitly about the Vintage era and is not intended to replace VFR navigation techniques being taught to real aircrew today in accordance with current requirements. Real aircrew must stick with the techniques they were taught and should make the maximum use of modern electronic aids and modern ATC to maximise safety at all times. This post is about how things worked (in general) before those possibilities existed.
FSAviator 11/06