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Post by phil533 on Sept 19, 2019 8:23:16 GMT -5
Take the DC-6B CB-16 Checklist for example
Starting Engines
Throttle set to 1000-1200 RPM (about 1/4 open) Manifold Pressure NOTE BAROMETRIC Boost Pump #3 ON
Throttle Stabilize at 1000 rpm Oil Pressure CHECK Boost Pump #3 OFF
*********************************************************** Before Takeoff
Run-up Complete Trim TAKEOFF Fuel Boost Pumps ON ******************************************************** Climb
Refer to Handling Notes for Climb procedure Fuel Boost Pumps OFF,
then ON over 10,000 ft Climb @ 170 kts, >500 fpm CHT Max 232C Maintain MAP with throttle as you climb ******************************************************* Before Landing
Max Landing Wt. (MLW) 88,200 lbs. Fuel Selectors MAINS Crossfeeds OFF Boost Pumps OFF ****************************************************
I had to look up aircraft booster pump on google. These things look like a world of their own. Some acting as primers and vapor cleaners.
So this post title is a question. Just done my first propliner DC-7 start. My first time MFS aircraft start ever, other than Ctrl - E.
I had a big hollow sinking feeling as soon as I hit the boot pump switch. A big world of the unknown.
Was this thing going to flood the engine? Does it really know what it is doing? Though I suppose I could ask the same question of my car computer.
Do the propliners have engine operated fuel pumps as well? Also an explanation of the climb phase, pumps off and then back on after 10,000 ft, would be a fit question for a pilot to ask I would imagine.
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Post by Tom/CalClassic on Sept 19, 2019 10:02:26 GMT -5
In general, yes they have engine powered fuel pumps. The electric boost pumps are used whenever those engine fuel pumps do not provide sufficient fuel flow to the engines, based on actual flight testing (so each aircraft’s boost pump usage will be different). They are always needed for starting (since the engine pumps are providing no fuel pressure), and often in high demand (i.e. almost full throttle) situations like takeoff and climb at high altitudes. As you climb, you increase the throttles to maintain a constant manifold pressure. As this gets to almost full throttle, boost pumps are often needed.
Hope this helps,
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Post by Dennis the menace on Sept 19, 2019 14:48:03 GMT -5
General rule of thumb regarding boost pumps.
1. Turn them on with each respective engine when starting. Once the engine is stabilized, turn them off so they don't foul the plugs. Taxi with them in the "off" position. 2. Turn them on prior to run up, and leave them on for takeoff, unless you have to hold an excessive amount of time. Leave them on through METO stage. 3. Turn them off after you have established climb mode. 4. Turn them on when on final. If you have to do a go around, you'll need them to be on. 5. Turn them off after landing when exiting the runway and raising the flaps.
That's about all there is to them.
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