Author Topic: Me109 G6 vs P51  (Read 5036 times)

Offline Stoney

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Re: Me109 G6 vs P51
« Reply #15 on: March 05, 2010, 05:56:05 PM »
if your fuel critical the first thing you should do is throttle back to normal power and climb to 12.5k (D) or 17k (B). Once your speed is in the high 300's then go to max cruise...

A bit of a hijack, but if you're fuel critical, the best thing you can do is accelerate to the speed that gives you best range at your current altitude, and then throttle back to the power/rpm setting that maintains that speed with the lowest fuel consumption.  With no tailwinds available in-game, you certainly don't want to climb, as the higher TAS at the higher altitude will not make up for the fuel you burned in the climb, regardless of the climb power setting.  This is the reason why Lindbergh flew on the deck the entire way to France.  If you have excess altitude, and are fuel critical, the most fuel efficient technique to return home is to immediately establish best glide speed, then cut the engine.  Glide at best glide speed until you have no more altitude to trade for speed, and then resume using the power-on, economy technique I described above. Further, if you're flying a long distance, and minimizing fuel consumption is a higher priority than speed, and you have the space to do it, it is always best to fly from point A to point B as close to the deck as is safe, and then only enact your climb at the minimum distance from the objective that allows you to reach your target altitude and/or speed. 

If you climb to any altitude in this game, full power (WEP even if available), will be the most efficient climb power setting, since you don't have to worry about engine health.  The only time using reduce power in a climb is advisable in AH is when you're trying to keep a formation together as lead.  You have to leave your wingmen with excess power to either keep in speed or climb.

I don't have time to post the equations to support these statements, but they're out there if you want to find them.
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Offline Baumer

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Re: Me109 G6 vs P51
« Reply #16 on: March 05, 2010, 08:13:24 PM »
To add a bit to what Stoney posted, looking at the manuals I have for the planes in game, (and I have tested this with the F6F and the F4U) once at minimum altitude, use the lowest RPM possible to maintain the glide speed to get the maximum range.

Obviously you need to be clear of any enemies but, lowest RPM/at glide speed/as close to sea level, will give you the best range for the fuel remaining.

 
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Offline Wmaker

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Re: Me109 G6 vs P51
« Reply #17 on: March 05, 2010, 08:26:06 PM »
With no tailwinds available in-game, you certainly don't want to climb, as the higher TAS at the higher altitude will not make up for the fuel you burned in the climb, regardless of the climb power setting.

In the case of Brewster in AH, I disagree. AH's Brewster pretty much gives the right cruise speed for cruise settings at 6k, if you are on the deck the cruise speed for the same power setting is over 70mph less!! So darn right it is wise to climb and acceletare to the cruise speed/altitude with full throttle before leveling out! And the cuirse speed at about 6k is about modeled right. Hard to stay if the low speed cruise speed is too low...

...if I made mistakes in my post it's all beer's fault....unfortunately...  :cry
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Offline boomerlu

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Re: Me109 G6 vs P51
« Reply #18 on: March 05, 2010, 09:39:12 PM »
I remember seeing graphs for the P51's airfoil geometry (CL vs AoA) compared with a normal airfoil. The P51's lift coefficient drops off at a lower AoA than the standard airfoil (higher stall speed). It's not just lift-loading, but available lift as well.
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Offline Krusty

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Re: Me109 G6 vs P51
« Reply #19 on: March 05, 2010, 09:51:58 PM »
It does no good to cruise on max fuel if you still end up ditching.

The best thing you can do is climb (not to the moon, mind you).

Why?

Because when you DO run out of gas then you can glide for a long distance, banking on that air cushion you built up underneath you.

Scenario 1: You stay low, cruise, eng dies 1 mile from the runway and you ditch.

Scenario 2: You climb, use more gas, eng dies 1 miles from runway, but you can glide her in and dead-stick the landing for a safe return.

You always want some alt under you, even if low on gas. Coming from a guy that makes tons of deadstick (no oil, shot out gas, damaged, etc) landings, it's a life-saver, virtually speaking.

Offline Stoney

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Re: Me109 G6 vs P51
« Reply #20 on: March 06, 2010, 04:35:32 AM »
I remember seeing graphs for the P51's airfoil geometry (CL vs AoA) compared with a normal airfoil. The P51's lift coefficient drops off at a lower AoA than the standard airfoil (higher stall speed). It's not just lift-loading, but available lift as well.



You can see visually what I was explaining above.  This was done from an analysis I did on XFOIL a few years ago.  And, to illustrate Boomer's post, this was the lift polar that was plotted for both aircraft.  Some of you have probably seen this before.  The La-7, from what I've found, used the 23XXX series airfoils.  These were plotted using the MAC for both aircraft to determine the Reynolds number at ISA.

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Offline Wmaker

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Re: Me109 G6 vs P51
« Reply #21 on: March 06, 2010, 08:41:50 AM »
In the case of Brewster in AH, I disagree. AH's Brewster pretty much gives the right cruise speed for cruise settings at 6k, if you are on the deck the cruise speed for the same power setting is over 70mph less!! So darn right it is wise to climb and acceletare to the cruise speed/altitude with full throttle before leveling out! And the cuirse speed at about 6k is about modeled right. Hard to stay if the low speed cruise speed is too low...

...if I made mistakes in my post it's all beer's fault....unfortunately...  :cry

Low alt cruise speed is what I meant, sorry. It was a rather suprising when I noticed the huge difference, ended up ditching a few times. :)
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Offline Strip

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Re: Me109 G6 vs P51
« Reply #22 on: March 06, 2010, 12:21:50 PM »
If you climb to any altitude in this game, full power (WEP even if available), will be the most efficient climb power setting, since you don't have to worry about engine health.  The only time using reduce power in a climb is advisable in AH is when you're trying to keep a formation together as lead.  You have to leave your wingmen with excess power to either keep in speed or climb.

I don't have time to post the equations to support these statements, but they're out there if you want to find them.

In game I believe this to be totally false, WEP in a pony is only worth a few hundred feet per minute over normal power yet consumes nearly twice the amount of fuel. If you find me with 50 gallons of fuel and 200 miles to home you certainly wont find me on the deck. You will not find me cutting the engine in and out alternating between climb and descend either. As the P-51 is the only plane that I have thoroughly tested the throttle settings on its the only plane I can comment on. This is probably why I can stretch the P-51's range on par with anyone in the game though.

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Offline Stoney

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Re: Me109 G6 vs P51
« Reply #23 on: March 06, 2010, 04:54:07 PM »
In game I believe this to be totally false...

I won't argue with you or Krusty, but when you test it, I'd be interested in the results.  Who knows, maybe I'm wrong?
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Offline Lusche

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Re: Me109 G6 vs P51
« Reply #24 on: March 06, 2010, 05:21:41 PM »
In game I believe this to be totally false, WEP in a pony is only worth a few hundred feet per minute over normal power yet consumes nearly twice the amount of fuel.

Hm

On deck, WEP consumes ~360gph, MIL ~300gph.

Conducted a little test: Pony D, 50%fuel, FB 2.0. Takeoff to 10k, timer starts to run when starting engine.

With WEP: Time 3:34, fuel consumption 21gal
With MIL: Time 3:54, fuel consumption 19gal.

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Offline Strip

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Re: Me109 G6 vs P51
« Reply #25 on: March 06, 2010, 05:32:45 PM »
Lusche,

Just like to point out I said normal power, which is 2700 rpm and 46" of manifold. Try running the level GPH test at 12.5k with the D or 17k with the B with normal power settings. You should get somewhere in the 1.60 to 1.70 range I believe from memory alone.

My computer is down so I cant test this myself or I would post the numbers.....

Strip
« Last Edit: March 06, 2010, 05:36:10 PM by Strip »

Offline Strip

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Re: Me109 G6 vs P51
« Reply #26 on: March 06, 2010, 05:41:16 PM »
Conducted a little test: Pony D, 50%fuel, FB 2.0. Takeoff to 10k, timer starts to run when starting engine.

With WEP: Time 3:34, fuel consumption 21gal
With MIL: Time 3:54, fuel consumption 19gal.

Just to add....

Lusche, your test does show me that it is better to use a reduced power setting. You used less fuel to climb the same distance and cover more distance at the same time.  I would be interested to see what 2700 rpm and 46" manifold would do in the same test.

We are starting to hijack this thread a bit and I dont want go down that road anymore. If we want to discuss this more perhaps we can start another thread? I am not interested in proving anyone wrong or right but I am curious and perhaps looking to improve upon what I do.

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Offline Lusche

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Re: Me109 G6 vs P51
« Reply #27 on: March 06, 2010, 05:42:41 PM »

Lusche, your test does show me that it is better to use a reduced power setting. You used less fuel to climb the same distance and cover more distance at the same time.  I would be interested to see what 2700 rpm and 46" manifold would do in the same test.

Doing it right now. :)

And yes, I completely missed "normal power" in your post.  :o

Conducted a little test: Pony D, 50%fuel, FB 2.0. Takeoff to 10k, timer starts to run when starting engine.

With WEP: Time 3:34, fuel consumption 21gal
With MIL: Time 3:54, fuel consumption 19gal.
With normal: Time 5:44, fuel consumption 17gal.
« Last Edit: March 06, 2010, 05:44:48 PM by Lusche »
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