Optimal gliding?

[Eisenfaustus]

Just to make sure I understood the concept:

 

If I wish to maximize the distance I can glide after the engine died I feather the prop, deploy flaps in takeoff position and trim the aircraft so, that I maintain optimal climbing speed in coordinated flight. 
 

Or does it work differently?

Edited September 19, 2020 by Eisenfaustus
False friend

[ITAF_Airone1989]

Not "climbing" but "gliding" speed, but I guess it's just a mistake.

 

Don't forget to close radiators, you don't need them anymore..

[unreasonable]

Not sure what you mean by "starting position".  I expect it varies from plane to plane but in the Spitfire MkI manual, for instance, the best long distance glide speed is given as 100mph IAS with flaps up. Flaps give more lift at a given speed but also slow you down. Planes with an adjustable flap my have their best glide performance with some flap down, but I doubt it would ever be at the full down position.  Some manuals give a best glide configuration and speed - best to check for your particular ride. 

Edited September 19, 2020 by unreasonable

[Eisenfaustus]

17 minutes ago, ITAF_Airone1989 said:

 

Don't forget to close radiators, you don't need them anymore

makes sense - thanks

11 minutes ago, ITAF_Airone1989 said:

Not "climbing" but "gliding" speed, but I guess it's just a mistake.

no it was no mistake - just honest ignorance. I thought it plausible that optimal climbing speed would be the speed at which the a/c attitude generates the greatest possible lift for any powersetting including zero. Thus I assumed it would be the optimal gliding speed as well. How do I know the optimal gliding speed?

4 minutes ago, unreasonable said:

Not sure what you mean by "starting position".  I expect it varies from plane to plane but in the Spitfire MkI manual, for instance, the best long distance glide speed is given as 100mph IAS with flaps up. Flaps give more lift at a given speed but also slow you down. Planes with an adjustable flap my have their best glide performance with some flap down, but I doubt it would ever be at the full down position.  Some manuals give a best glide configuration and speed - best to check for your particular ride. 

here another assumption of mine - I guessed planes that use their flaps during takeoff (starting was a false friend derived from my mothertounge where we call the takeoff start ^^), would benefit more from lift then be hindered by drag in lower speed regimes by their flaps in takeoff position then the other way around. 
 

might be completely wrong though - that’s why I am asking ^^

[ITAF_Airone1989]

Here you can find glide speed for every aircraft:

 

Here is a topic I opened some time ago about best climb speed:

 

Climb and glide is not the same, also because when you climb you use your engine trust while during the gliding your engine is dead/idle.

Example: 

Bf-109 G2 climb speed: 270km/h

Bf-109 G2 glide speed: 200km/h

So, to answer to your question I guess that the speed that you want to keep is really close to the glide one...

[Eisenfaustus]

So the glideslope speed in the ingame manuals is the optimal speed for greatest possible distance?

Ok sounds plausible - thanks ^^

[unreasonable]

Generally this will be with flaps up - there may be the odd exception.  The 109 G-2 manual, for instance, says that to make best use of the glide ratio, extend flaps (and gear) only below 1000m - ie in preparation to land, and this is a plane with a recommended take off flap setting of 20 degrees.  

 

 

[AndyJWest]

There is a correlation between best climb speed (VY in modern aviation terminology) and best glide speed:

 

Quote

VY
— Best rate-of-climb speed. Delivers the greatest gain in altitude in the shortest time. Flaps and gear up. Decreases as weight is reduced, and decreases with altitude. Lift-to-drag ratio is usually at its maximum at this speed, so it can also be used as a good ballpark figure for best glide speed or maximum-endurance speed for holding.

 

https://www.flyingmag.com/everything-about-v-speeds-explained/

[Eisenfaustus]

16 hours ago, AndyJWest said:

There is a correlation between best climb speed (VY in modern aviation terminology) and best glide speed:

 

 

https://www.flyingmag.com/everything-about-v-speeds-explained/

Ok - so I’m not that stupid after all ^^
 

So greatest possible distance will then be travelled with best climbing speed and flaps up?

[AndyJWest]

6 hours ago, Eisenfaustus said:

Ok - so I’m not that stupid after all ^^
 

So greatest possible distance will then be travelled with best climbing speed and flaps up?

 

As the bit I quotes days, it is a 'ballpark figure' for best glide. Frankly, I doubt anyone really knows what the best glide speed was for most WW2 aircraft, to a much  better precision. As for flaps, it may depend on their type. If an aircraft has split flaps, you certainly don't want them open much - and quite likely not at all. Maybe with say a P-51 or a Bf 109, there might be a slight advantage in dropping them a little, but the difference it is going to make isn't going to be great. 

 

One other thing, you mentioned feathering props. This is only an option on some of the twin-engined aircraft in IL-2 GB, and none of the single-engined ones. For non-feathering props, the best you can do is move them to the high pitch/low rpm position, though depending on the prop mechanism, and the damage that stopped the engine in the first place, that may not be possible (assuming that IL-2 accurately models such factors). A windmilling prop creates a lot of drag, and that is likely to have more effect on glide performance than minor differences in speed or flap angle.