Author Topic: AH Engines (Read 344 times)

SirLoin · « **on:** December 29, 2001, 09:13:00 AM »

Why is it that on some planes(eg,Lancaster,P38..ets) when you kill the engine in flight it will slow to a stop(and then have to go through full startup to get going) but on others(eg..P51,Spitfire..etc)the props will windmill?(and start instantaneously)I'm just curious as to why it is modeled this way.I would also like to know if a fully stopped prop causes more drag than a windmilling one in AH.(for aurspeed bleeding purposes)...<S!>

Kieran · « **Reply #1 on:** December 29, 2001, 11:14:00 AM »

Part A I can't help; Part B, in my experience you want to feather the prop if you want to go deadstick. I can glide farther deadstick (or at least I believe I can) if I feather.

Karnak · « **Reply #2 on:** December 29, 2001, 02:19:00 PM »

Multi-engined aircraft can feather their props to reduce drag from a dead engine. This woukd not assist a single engine aircraft and thus their props windmill.

That would be my guess anyways.

SirLoin · « **Reply #3 on:** December 29, 2001, 06:11:00 PM »

Yes,thnx Karnak..But to my knowledge only ME109's could set prop pitch to feather..All others were constant speed.And why a P38 and not a P51?...Same engines..

Karnak · « **Reply #4 on:** December 29, 2001, 07:04:00 PM »

P-38 and P-51 do not use the same engines.

The P-38 uses Allisons and the P-51 uses a Merlin. The Spit and Lanc in your originaly example also use Merlins.

I don't think the engine type has anything to do with it though. It is an added control to all multi-engined aircraft so that they can fly with one or more engines out. When a prop is windmilling it adds drag and vibration to the aircraft, both of these (particularly the drag) can cause problems for the aircraft. By feathering the prop of the dead engine, the windmilling is stopped.

SirLoin · « **Reply #5 on:** December 29, 2001, 07:27:00 PM »

Well that proves my point.The Spit and Lanc use same engines but one can stop it's prop and the other can't..And is that an advantage is my main question?..<S!>

Karnak · « **Reply #6 on:** December 29, 2001, 07:31:00 PM »

SirLoin,

What I am saying is that it is an added control, not a part of the engine.

It is a required control of multi-engined aircraft.

SirLoin · « **Reply #7 on:** December 29, 2001, 07:35:00 PM »

Karnak,thank you for spelling it out for me.I see the reasoning for it now..WoW1!..Is HTC's ever on the ball!!..

Durr · « **Reply #8 on:** December 30, 2001, 01:54:00 AM »

By the way, ability to feather the prop is useful to single engined aircraft as well since it increases the glide distance. For example, in the T-34 which is a Navy trainer aircraft, with the prop feathered you have a 12:1 glide ratio, but with the condition lever set to full increase, you only have about a 2 or 3:1 glide ratio. In practical terms this means that if you lose your engine at say 10,000 feet you would be able to glide 20 miles with the prop feathered but only about 3 miles or so with the prop turning. Thus, one of the most important steps of the EP for engine failure is the 4th one: condition lever to feather.
I dont know if any of the single engined fighters in AH had the ability to feather their props although I think that the F-4U could at least. It has a prop pitch control in the throttle quadrant, and it seems logical to me that you would be able to set it to feather.

RabidSquirrel · « **Reply #9 on:** December 30, 2001, 02:25:00 AM »

Karnak,just for some information about the P-38 and P-51,when the first P-51's were built (them being the P-51B)they used Allison engine's. It wasn't until the P-51D came out that they added the more powerfull Merlin engine's. But everything Durr said is in fact true.

AH Pilot,
Squirral

SirLoin · « **Reply #10 on:** December 30, 2001, 02:39:00 AM »

I thought only ME109's had the ability to feather their props?They had pitch control instead of constant speed prop.

Karnak · « **Reply #11 on:** December 30, 2001, 05:24:00 AM »

Squirral,

Yes, I am well aware of that.

However neither of the P-51s in AH have Allison engines.

pugg666 · « **Reply #12 on:** December 30, 2001, 08:10:00 AM »

Squirral,

the 51B had a merlin engine.it was the 51a, a-36 that had the allison.
just nit picking

CRASH · « **Reply #13 on:** December 30, 2001, 10:26:00 AM »

It is my understanding that prop rpm as relates to drag is not yet modeled in AH. I believe from having read the very early posts on the topic that it was htc's intent to model it but I guess it's been overlooked for more important features. I'd like to see it modeled, expecially for the bomber guys.

CRASH

Blue Mako · « **Reply #14 on:** December 30, 2001, 08:38:00 PM »

Quote

Originally posted by CRASH:
It is my understanding that prop rpm as relates to drag is not yet modeled in AH. I believe from having read the very early posts on the topic that it was htc's intent to model it but I guess it's been overlooked for more important features. I'd like to see it modeled, expecially for the bomber guys.

CRASH

It IS modelled. You can glide further with RPMs lowered than with RPM set at full.