DC-6B Troubles

[Deleted]

I must be doing something embarrassingly wrong with the FS2004 DC-6B. On climb out, once I raise the flaps the aircraft pancakes to the ground. It simply won't stay airborne without full flaps.

What am I doing wrong?

Thanks

[raymengel]

Hi Neptune,

What is your take off weight? If you are taking off with full fuel load plus passenger & baggage, you may be somewhat overweight? You may have to drop some fuel or pax & baggage weight??

Also--are you taking off with full flaps? I think most takeoff's are made with less than half flaps selected. Full flaps seems like a lot of drag out there on take off. I think there is a checkoff list on the "knee board" advising you what flap setting to select for take-off.

Are you decreasing your flaps in increments or are you dumping all your flaps at once? If you dump them all at once you are loosing what lift is there and the aircraft will not stay airborne. As your rate of climb is established and indicated airspeed builds up on climb out then you can bring up your flaps in increments.

What is your rate of climb after take off? If it is too much you may need to decrease it some until you have better airspeed built up.

I am sure others who read your post may have more suggestions than what I can think of at this time.

Hope this helps--don't give up as the propliners can at times be a handful to fly at times.

Ray Mengel
Spokane, WA

[Tom/CalClassic]

Hi,

First thing to try - load the default Cessna at Sea Tac Flight, switch to the DC-6B, and take off. If it's fixed, reload this flight, change what you like, and save a new default flight.

If not, then in line with what Ray says, refer to the Reference file (press F10 while flying) and follow those takeoff instructions very carefully. Use the Fuel and Payload menu to be sure you are not over takeoff weight.

Hope this helps,

[Colonial]

Trim trim trim!

When I started (i'm not an old salt on the props like many of our distinguished members) I never truly appreciated 'takeoff trim' and used to wonder why some models couldn't get off the ground.

It's the trim laddie!

[colorado]

Hi Neptune!

My 2 cents is along Ray and Tom's line, suggest that you check your airspeed. If you're sinking back to the ground it sounds like airspeed may be too slow.

Flying by visual reference in the big propliners is not the same as the default Cessnas, Mooney, or King Air, and it is easy to try to climb too steeply by visual reference only.

After takeoff I have to consciously flatten out my initial climb in order to build up airspeed, especially in the 4-engine liners.

Also check fuel and passenger load, if the DC-6, DC-7 or Connie are fully fueled with max passenger and baggage loaded they are much more sensitive to correct airspeed --even at sea level. When I fly out of Cheyenne or Denver the takeoff weight makes a huge performance difference in addition to proper airspeed (and also continued evidence of FS Aviator's high fidelity flight model!).

I don't use full flaps for the propliners on any "normal" takeoff, but on occasion I've experimented with a lightly loaded DC-6B from "bush" fields and I may use about 3/4 flaps for a gravel short-field takeoff -- but usually just to see how things behave.

Hang in there and keep trying. The propliners are procedure intensive compared to many (most) of the rest of the FS9 hangar -- even the "shop heaters" (jetliners) have enough extra power to fly through some bad handling. "Real Planes" like the kind of attention to detail that made the real life originals such classics.

v/r
Jack

[colorado]

Second the trim suggestion too! Makes all the difference!

Colorado!

[pung]

You also might check you power, some joysticks & setting don't always give full power, and you need to hit your F4 key for maximum power.

[Tom/CalClassic]

On my DC-6 panel, setting takeoff trim is easy. Just click those words painted on the panel.

[Deleted]

Thanks all. It was apparently an overweight condition, though I had to set the fuel and payload way below maximums.

I had been following the checklist: 2 points of flaps, +4° elevator trim (I have joystick buttons programmed for elev. trim), taking off from KPHX (elevation 1123 ft.). V1 and V2 were okay, climb out seemed normal at about 500 fpm with +10° elevator trim. About 1000 AGL, 128 KIAS, I'd dump one notch of flaps and she'd just fall out of the sky.

It's still tricky with the reduced weights, but I was actually able to make a complete circuit and land. I also waited until I had a bit more airspeed and altitude before incrementally raising the flaps.

I've been flying FS since version 5, and propliners since FS98, but I've been away for a while and just couldn't figure out what was going on.

It's a nice model, altogether. Thanks Tom and all for making this all happen.

Regards,
Bruce

[sunny9850]

One thing that caught me out a few times was the drag added by the cowl flaps. If you're like me used to select full open for take-off as just about all the high performance singles and twins require warm conditons thent that may be what causes your sluggish performance.

Set them to about 1/3 open and try your takeoff again.
Full flaps are definitely not a good idea....the added drag outweighs the lift you might gain.

[billbrocker]

Lots of good advice there. Don't forget FS like to load an aircraft with full fuel if it's not a previously saved flight. I've made that mistake far too often (slow learner) and found myself using the "grass strip" at the end of the runway as well as all the pavement. So don't forget to check your fuel before each flight.

[qar02]

Hello;

This "stall on flaps retraction" isn't limited to just one user. The question that I have is: Why would I have to readjust fuel load (down 50%) on a config that has repeatedly flown successfully before? The people who wrote the Config file have tested it and the Aircraft is within historic limits. The Starliner did this to me some months ago...and now all-is-well. It wasn't field altitude (860 ASL) or wind or temperature that was out of limits.

This never happens in lighter aircraft...twins or singles.

Is this an MS FS problem?

v/r

qar02

[qar02]

Oooops...ps.

Forgot to mention: I have a Saitek Throttle quadrant and sometimes...I don't know why yet...FS and the Saitek load the throttle settings with very bad "Null" and "full throw" values. But, again, this appears to be random and I suppose that not many of us double check all of our Settings every time we load a sim.

Still, there has to be some sort of glitch or loop going on in FS that sets us up for the problem.

qar02

[Tom/CalClassic]

One problem is your resetting the trim to +10 - way too much. I keep it at +4 all the way to climb power (and then it's usually quite close to that during climb). Here is FSAviator's reply:

Greetings Bruce,

I can see that you are trying to follow the supplied handling notes, and of course reducing operating weights may allow an aircraft to avoid stalling, but there is a wider issue here that is worth illuminating and which in light of the more detailed information now provided seems to be the cause of the problem. When we fly propliners we have to achieve our 'operating targets' in a very specific sequence.

<<I had been following the checklist: 2 points of flaps, +4° elevator trim (I have joystick buttons programmed for elev. trim), taking off from KPHX (elevation 1123 ft.). V1 and V2 were okay, climb out seemed normal at about 500 fpm with +10° elevator trim. About 1000 AGL, 128 KIAS, I'd dump one notch of flaps and she'd just fall out of the sky.>>

The R-2800-CB16 powered DC-6B on screen handling note TAKE OFF phase section mandates;

***************************
TRIM + 4 degrees <<<<<<<<<<< 1
FLAP = STAGE 2
COWL FLAPS = 4 degrees
CALL for TOGA POWER (2400hp)

ROTATE at 115 KIAS (@ 103800lbs)
Establish positive rate of climb
GEAR UP
ACCELERATE > 130 KIAS @ <= 500 ft/min<<<<<<<< 2
CLIMB 300 feet AGL <<<<<<<<<<<<< 3
FLAP = STAGE 1
ACCELERATE 140 KIAS @ <= 500 ft/min <<<<<<<<<< 4
FLAP = UP
Establish 500 VSI <<<<<<<<<< 5
CALL for METO Power (1800hp)
*******************

Neither the sequence nor the targets are optional. After we rotate we must *prevent* climb so that we accelerate to 130 KIAS *before* we reach 300 AGL. If we are heavy and the weather is adverse we 'may' need to climb at less than 500 VSI to achieve 130 KIAS before 300 AGL.

The trim setting of +4 is not imposed to assist rotation or to assist climb. It is imposed to *prevent* both without manually applied back pressure on the yoke. PLUS 4 trim is explicitly imposed to promote acceleration, and deter climb. We apply it before take off explicitly so we will need to fight it to rotate and fight it to climb. We must avoid premature unstick and we must avoid significant climb rates. To stay alive we must accelerate to the right side of the drag curve as soon as possible. Any tendency to sink is easily corrected with back pressure on the yoke. The thing we dread most is a stall. We do not trim to promote climb during the TAKE OFF phase. We trim to promote acceleration. We can only use TAKE OFF power for a very limited period and we must achieve not just 130 KIAS, but also 140 KIAS, during that very limited time period. Note that the 140 KIAS operating target is inside the TAKE OFF phase of the flight (handling notes).

Our first two operating targets are 130 KIAS *below 300 AGL*, to raise FLAP 2 immediately after passing 300 AGL, and 140 KIAS as soon as possible after that to raise FLAP 1. Other than, 'establish positive rate of climb', we have no VSI targets until we have achieved *both* IAS targets.

The handling notes mandate +4 trim for the entire TAKE OFF phase. It is incorrect to alter pre take off elevator trim to relieve the back pressure until after we exit the section of the handling notes within which it is mandated, incorrect to exceed 300 AGL without achieving 130 KIAS, and incorrect to raise FLAP 2 at only 128 KIAS. Those actions in combination may cause a DC-6B to crash because they are the wrong operating targets for a DC-6B in the wrong sequence.

We should not retrim the aeroplane from the TAKE OFF phase trim of +4 to promote a VSI target until we have a VSI target. PLUS 4 trim is applied explicitly to promote the IAS targets which are the targets of the TAKE OFF phase. We only retrim for climb after we have met all of our acceleration targets and all of our associated configuration change targets. We must achieve all those IAS targets and all of the configuration change targets long before we reach 1000 AGL. We need 140 KIAS airflow over the wings before the end of the take off phase (while we still have access to TAKE OFF power). It may not be possible to achieve the required acceleration from the wrong side of the drag curve to the right side of the drag curve (=> 140 KIAS) using only METO power from three engines if we suffer an engine failure. We *need* 140 KIAS in a hurry. We must never reach 1000 AGL still stranded on the wrong side of the drag curve at only 128 KIAS.

We alter our trim from +4 to that which delivers 500 VSI only after we have achieved 140 KIAS and only after we have retracted FLAP 1 (normally well below 500 AGL) . We do not alter the pre take of trim of only PLUS 4 until it has 'promoted' 140 KIAS by 'preventing' climb. We don't want the aeroplane to climb. TAKE OFF power is not used to climb. TAKE OFF power is used to accelerate the aeroplane to the right side of the drag curve (=> 140 KIAS). When we need to accelerate fast to survive we must not start to climb a hill. We must restrict climb at least enough to achieve the IAS targets specified before any height specified and before any TOGA time limit expires.

The 'eureka' moment in propliner simulation is the moment when we grasp that each step in the handling notes is simple and logical and strictly sequential. If we use 'realistic' flight dynamics we must sequence the 'realistic' operating targets correctly else we may crash with the aeroplane stranded on the wrong side of the drag curve. All the early sequential operating targets in a flight are 'safety critical'. Eventually we transition to targets imposed only by our virtual employer which are only profit maximising targets.

Let's take a moment to consider the weight issue raised by others.

The regulatory authority have checked that the aeroplane can achieve each of the handling note targets in sequence at every weight up to maximum certificated gross weight. All the targets above can be achieved in sequence at any weight that is not shown as an illegal overload in the MSFS payload and fuel menu.

Weight relates to runway length and headwind vector. We may be too heavy to achieve rotation IAS with the current headwind vector on a given runway, but if the runway is long enough in today's weather, at today's runway altitude, after we rotate at 115 KIAS the aeroplane will do all the above at any weight up to max gross. Whether the runway is long enough is a flight planning issue, not an operating target issue or a flight dynamics issue. If we need to depart short runways, or have too little headwind vector down the runway in use, then we may need to depart at less than max gross weight (today), but we *never* need to depart at less than max gross weight to comply with the supplied handling notes. If we are heavy, or the weather is adverse, or both, it just takes longer to achieve each target, one by one, in the mandated sequence.

The fact that it takes longer to achieve 130 KIAS when we depart at max gross does not mean that we may exceed 300 AGL whilst perusing that safety critical target. It means we must restrict VSI even more (using the yoke) so that we always reach 130 KIAS before 300 AGL regardless of weight. The climb rate and associated pitch attitude required to achieve 130 KIAS *before* 300 AGL is *always* compatible with safe retraction of FLAP 1 just above 300 AGL having already achieved 130 KIAS and whilst in the process of accelerating beyond 130 KIAS to the next target of 140 KIAS still with + 4 trim applied.

*****************************
TRIM + 4 degrees <<<<<<<<<<<<<<<<
ROTATE at 115 KIAS (@ 103800lbs)
Establish positive rate of climb
GEAR UP
ACCELERATE > 130 KIAS @ <= 500 ft/min
CLIMB 300 feet AGL
FLAP = STAGE 1
ACCELERATE 140 KIAS @ <= 500 ft/min
FLAP = UP
Establish 500 VSI <<<<<<<<<<
CALL for METO Power (1800hp)
*********************************

Propliner flying is all about compliance with demanding operating targets, one by one in a strictly defined sequence, whether those are imposed by the specific design limits of the aeroplane and its engines, or by ATC procedures. Propliners with 'realistic' flight dynamics are carefully designed to be fully compliant with both, but they will readily go out of control at low IAS on the wrong side of the drag curve if the required operating targets are not achieved, or not properly sequenced, at any weight. This is all about accelerating in shallow climb at low pitch to 130 KIAS below 300 AGL and then accelerating to the right side of the drag curve (=> 140 KIAS) with + 4 trim still applied before trimming for 500 VSI. We must discipline ourselves to target acceleration to the right side of the drag curve after unstick.

If the aeroplane stalls at max gross weight when the correct targeting sequence is followed the flight dynamics are badly corrupted. It shouldn't even sink! It should be very easy to achieve 130 KIAS below 300 AGL with the correct trim applied after rotating at 115 KIAS. If that is difficult rename your existing aircraft.cfg to retain additional liveries. Download and install all parts of the latest flight dynamics and handling notes then paste only your additional liveries into the latest aircraft.cfg.

Always check that *all* your liveries alias the correct air file.

[fltsim.0]
title=Douglas DC-6B United Air Lines
sim=dc6b <<<<<<<<<<<<<<<<<<<<<
model=
I cannot rule out a whole series of other problems relating to personal hardware configuration issues, content of personal start up flights etc, however handling notes are sequential and failure to give absolute priority to getting any aeroplane onto the right side of the drag curve during the take off phase, and before attempting climb, is paramount even when nothing is misconfigured.

FSAviator.