Author Topic: Propeller drag question (Read 493 times)

Naudet · « **on:** April 09, 2002, 04:40:43 AM »

Ok i am just wondering about the followig.

Does a nonpowerd rotatong propeller produce more drag than a standing propeller?

I found that out after i got a engine hit with a complete standstill of the propeller.
I was amazed how far i could glide with the standing prop.

On another occasion i had a radiator hit, and cut the engine before it died. Propeller still rotating. I had the bad feeling i deaccelerated much faster.

If that is so, can we please have a gliding-position switch for the propeller?
So we can stop it in the air to glide greater distances? Also with the abilitly to start it again for shrt power bursts?

fffreeze220 · « **Reply #1 on:** April 09, 2002, 05:46:53 AM »

I am not sure but i geuss the RPM settings for the Propeller have some thing to do with that. I figured out that landing is little bit easier when u set the RPM down short before u reach the runway. The drag sems to be lowered then. But i am not 100% sure.
Does any 1 know the effect between RPM and throttle and drag ?
If so does any1 know how to set throttle and RPM on 1 axis?
I cant do it because the axis for throttle is inverted?
Any 1 have a cue how it wrks cause i heared it once in the MA that some 1 told me its possible. But that was before the last update since we have the movement of the axis shown up in the setup from ur stick where u can set inputs.

thx

fdiron · « **Reply #2 on:** April 09, 2002, 07:00:26 AM »

I know that the F4u is a beast to land without breaking the wingtip off on full rpm. However, if I reduce the propellor rpms to minimum then I can land without any problems.

hitech · « **Reply #3 on:** April 09, 2002, 09:10:06 AM »

Rotating props produce a lot more drag than ones standing still.

And drag can be minimized by lowering rpm.

fffreeze220 · « **Reply #4 on:** April 09, 2002, 11:21:37 AM »

but Ht is it possible to set RPM and throttle on 1 axis ?
I saw that the axis from my trhottle is reversed in AH. Is there any way to change it so i can use RPM together with throttle setting ?
Isnt it that when i lower MAN that the RPM should be lower ?
I am not that used to the relations between RPMs and the MAN Boost

AcId · « **Reply #5 on:** April 09, 2002, 11:55:15 AM »

Would be nice to be able to set a few things to a rotary axis, I guees RPM would be nice, Trim too.

Starbird · « **Reply #6 on:** April 09, 2002, 12:16:17 PM »

freeze, do a search for constant speed or variable pitch propellers on this board. there has been a lot of discussion about how they work already.

Basically the prop will set itself for the best pitch at a single speed, no matter what you do. Theres no real need to adjust rpm in normal instances in AH.

funkedup · « **Reply #7 on:** April 09, 2002, 03:30:57 PM »

The prop automatically adjusts its pitch to maintain the RPM you have set.

Now imagine the engine is off, and the "wind" is making the prop turn rapidly. If you set RPM to zero or minimum, which way will the pitch move?

Seeker · « **Reply #8 on:** April 09, 2002, 04:10:38 PM »

you set RPM with the key pad +/- keys.

Turning it to full fine will definatly extend your glide.

Some people claim it extends range, others contend it extends time aloft.

It's possible to set each engine seperatly on a multi engined plane.

BigCrate · « **Reply #9 on:** April 09, 2002, 07:07:11 PM »

I have a few ?s.

The RPM gauge we have in the cockpit is for what??
Engine RPM or Prop RPM

If I have RPM 1 programmed to my throttle that controls what??

And the buttons +/- are just for Prop RPM or for both prop and engine RPM??

I fly the 38 the most and I have read that the props angle should be set to fine and throttles chopped. When diving to high speeds.

I have a split throttle I have both throttle and RPM programmed to both levers. I just need to know wha does what.

Thanks for yall's help
Cw
=Twin Engined Devils=

superpug1 · « **Reply #10 on:** April 09, 2002, 07:19:44 PM »

Maybe the props rotation is too slow and the air just hits it. o and if theirs a prop trim it would work better to use it.

and remmenber always

superpug1 · « **Reply #11 on:** April 09, 2002, 07:20:49 PM »

hope you liked the picture found it in my dads files.

Seeker · « **Reply #12 on:** April 10, 2002, 04:40:11 AM »

RPM is engine RPM (as modeled in game).

I've no idea if this is technicaly correct, certainly not for every plane, but the way I've always understood it is this:

Throttle controls the amount of air the engine can draw (manifold pressure), it's assumed the engine is always at full gas, trying to run flat out.

The RPM *controls* (the +/- keys) control prop pitch, which in turn has a direct influence on how fast the engine can spin (the RPM gauge).

I think that's about it.

Best way to test it is to use alt-X to set a speed, any speed, and let the plane settle into a steady state. Then start playing with the RPM and see what happens to the rate of climb meter, both with and without a running engine.

Wilbus · « **Reply #13 on:** April 10, 2002, 06:06:57 AM »

When the prop is rotating alot of energy goes to rotate it, if it's standing still it's just producing some drag.

Take a look a modern gliders, they glide great (as they should) and the acceleration/deacceleration is terrific. Although a prop plane has got a prop to pull/push it, the prop is allso a brake and the reason no prop planes can go supersonic (with prop still attached).

Starbird · « **Reply #14 on:** April 10, 2002, 08:58:00 AM »

RPM adjusts prop RPMs. Engine rpm's are basically irrelevent. Most props are connected directly to the output shaft of the engine, so both would be the same in those instances.

On something like a 109, I beleive they used gears going from the engine driveshaft to a cog on the prop hub, so there would be room for the hub cannon. Same type of thing for the P39. Once geared, you coudl have the prop and engine running at different speeds, but I'm not if this was done.

On a constant speed prop you have no direct control over the pitch. You set a certain rpm, and the prop will move to keep that rpm. I'm pretty sure most (if not all?) planes in AH had this type of prop in real life. I'm not certain tho.

On a variable pitch prop, there might be 2 or 3 settings you can choose from, but the prop wont adjust itself to keep a certain rpm. You would have to watch for overspeed and such in this instance. I believe someone mentioned that early spitfires had this setup.

AH treats every plane as a constant speed prop. If you keep the rpm setting at its highest, the prop will go as fast as its design allows, if there is enough power from the engine.