Couple of Early P-38 FM Observations

[Vermillion]

Even "post patch" it still has unnatural E retention (lack of induced drag) in comparison to the rest of the planeset.

I don't think the roll has changed at all though   This should be the biggest weakness of the P-38 series, and its not even a minor inconvience in AH.

Nice Observations and work Wells and Mig Eater.

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Vermillion
**MOL**, Men of Leisure
 
 

[This message has been edited by Vermillion (edited 03-02-2000).]

[funked]

Vermillion, it seems to have plenty of roll delay at slow speeds.  At higher speeds it should and does roll real nice due to the hydraulics.

[wells]

Without the hydraulics, I think the roll maxed out at 250 mph or so...not too impressive.  With the aileron boost, you can keep rolling faster right up through 600 mph if ya want!  You gotta watch that you don't pull max G's and roll at same time over 250 mph, could break a wing off!

[Citabr]

well whatever the case the 38 seems to matchup well with the other planes

The p38l has 1121 kills and has been killed 1171 times.
The F4U-1C has 627 kills and has been killed 309 times.
The P-51D has 346 kills and has been killed 233 times.


The p38l has 83 kills and has been killed 169 times against the F4U-1C

 The p38l has 75 kills and has been killed 109 times against the P-51D
 

 The p38l has 127 kills and has been killed 137 times against the Spitfire Mk IX
 

 The p38l has 19 kills and has been killed 21 times against the Bf 109G-6
 

 The p38l has 46 kills and has been killed 49 times against the C.205
 
The p38l has 34 kills and has been killed 23 times against the Fw 190A-8

The p38l has 44 kills and has been killed 47 times against the N1K2

The p38l has 10 kills and has been killed 21 times against the La-5FN


I'm just not seeing the effects of these so called problems in the stats  

in actual combat it performs as expected and as it should. it outaccelerates, climbs, and turns, and goes fast and has nice guns.

(fangs reared and cornered Citabria valiantly defends his lightning from claims of uberness)

[Citabr]

btw the lightning in AH fully compresses at 500 ias I guess as a way to simulate having dive flaps.

have you guys bothered to test the stall model? have you seen how violent it is and how spins are totally unrecoverable without an experienced pilot at the controls?


oh I guess were just looking for things to make worse on the 38 so our own rides will be better.

well relax cause the p38 isnt hard to kill

sorry I guess I'm ranting again  

[Vermillion]

Citabr,   I think you will find that most of the guys that have posted in this thread pick on all the planes that they find a problem with. Not just the ones they don't like or don't pilot.

Me, I fly the Pony, and just last week was putting up a bug report on it ordinance loadouts (carries too many rockets, while carrying bombs).

We just all want the planes to be as close as possible to what they really were.  Thats what seperates a simulation, from an arcade game.  

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Vermillion
**MOL**, Men of Leisure
 
 

[This message has been edited by Vermillion (edited 03-03-2000).]

[leonid]

What people may not be aware of is that the P-38 had a very high aspect ratio, probably only to be exceeded by the Ta-152.  This results in significantly reduced induced drag.  Frankly, I'm not surprised by it E-retaining capabilities.

Incidently, aspect ratio is:

(wingspan * wingspan) / wing area


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leonid, Komandir
5 GIAP VVS RKKA

"Our cause is just.  The enemy will be crushed.  Victory will be ours."

[This message has been edited by leonid (edited 03-03-2000).]

[niklas]

leonid, that is not the whole truth!

the induced drag coeffizient Cdi is

Cdi= Cl^2 / pi*AR

Cl = lift coeff.
AR = aspect ratio

a high AR is good for a low induced drag, but more important is a low Cl (C_lift)value.

And Cl is for a constant horzontal flight proportional to the wingloading

Now letīs have a look to the acīs:
weight P38L : 17500lb
weight 109G10: 6800lb
wing area P38: 328 ft^2
wing area G10: 177 ft^2
wingspan P38 : 52ft
wingspan G10 : 33ft

wingloading P38: 53 lb/ft^2
wingloading G10: 39 lb/ft^2
ratio: 1.36

Ar P38: 8.2
AR G10: 6
ratio. 1.36 (ups, almost the same:-))

Powerloading pounds/horsepower
P38: 5.5 lb/hp
G10: 3.7 lb/hp
ratio 1.48

ok, the P38 has a better AR, but at the same time a worse wingloading. And wingloading has a (^2) in the formula for the Cdi :-)

So the induced drag coeffizient of a P38 is imo very high

Hope i didnīt make some mistakes with the formulas:-)

Now letīs see how a p38 performs in AH.

gliding: cut off the enignes in 6000ft, autospeed 160. note neg. climbrate in 3000ft.

P38L : -1300ft /min
G10  : -2000ft /min
Hell, a 17500lb ac glides so much better than a 6800lb fighter.

Then i tried a constant 4G turn, full cirlce near the ground (360° turn), starting from 400mph

after that full circle the remaining speed was:
P38: 285mph
G10: 230mph

sorry, P38 is still too good imo
niklas

[This message has been edited by niklas (edited 03-03-2000).]

[wells]

Induced drag for 4G 300 mph

P-38L (17500 lbs) - 2500 lbs
109G10 (7400 lbs) - 1167 lbs

You're right Niklas, but...

Speed loss/time (acceleration) @ 300 mph, 4G's, g = 32 ft/sec/sec

P-38L - 2500g / 17500 = -4.57 ft/sec/sec
109G10 - 1167g / 7400 = -5.05 ft/sec/sec

The 109 should slow faster!  As it slows, it needs more Cl to make the 4G's and it's drag goes up even more in proportion with the P-38.

Glide performance is the same relationship as it's also a measure of deceleration for given speed and G load.

[Vermillion]

Ok Wells let me see if I am getting this straight.

Lets assume that the G10 induced drag in AH is correct.

By your numbers of -4.57 and -5.05, then ratio these, the P-38L should have 90.5% of the drag of the G10. Ok I can see that.

Now, in your last sentence you indicated that the drag you calculated is a linear relationship to the glide slope test that Niklas did.

But when we look at the ratio of glideslope , -1,300 ft/min to -2,000 ft/min , this will produce a ratio relationship of 65%.

So am I correct when I assume that, this means the P-38L only has 65% of the drag that the G10 has in Aces High, instead of the 90% historical?

Realize I am trying to remember these relationships in my head from work, and I may be confusing too many issues and variables here including the lack of parasitic drag. But even still I would think that the P-38L should have more parasitic drag than the G10 would *shrugs*.

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Vermillion
**MOL**, Men of Leisure
 
 

[This message has been edited by Vermillion (edited 03-03-2000).]

[Pyro]

Niklas, you are correct.  I pooched my last calculation because I forgot to take a higher Cl into account.  My bad, I'll get it fixed.  Thanks for pointing it out in a way that made me realize what happened.



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Doug "Pyro" Balmos
HiTech Creations

"If it's stupid but works, it's not stupid."

[wells]

 

By your numbers of -4.57 and -5.05, then ratio these, the P-38L
                should have 90.5% of the drag of the G10. Ok I can see that.

Not drag, acceleration.  You can see that the P-38 has much more drag than the 109, as Niklas pointed out.

 

Now, in your last sentence you indicated that the drag you calculated
                is a linear relationship to the glide slope test that Niklas did.

Acceleration is directly related to climb/glide rates.  I don't really know what the planes weigh in AH but I recall Pyro saying that it was 'about' 7400 lbs.  If I do the calc for 6800 lbs as in Niklas' post, it looks like this...

300 mph, 4G's (109G10)

a = -4.64 ft/sec/sec

, much more comparable to the P-38.  It looks that maybe the 109G-10 could be even heavier than 7400 lbs, 7700-7800 maybe?  Pyro?

Niklas, were you carrying a drop tank or gondolas or anything?

[funked]

Citabr:
"btw the lightning in AH fully compresses at 500 ias I guess as a way to simulate having dive flaps"

You are confusing compressibility with high  control forces caused by high dynamic pressure.

The posted dive limit was Mach 0.65.  Above Mach 0.74 it should suffer uncontrollable nose-down pitching and vibration.  From AHT:  "if the aircraft hung together control could finally be re-established in the warmer denser air of lower altitude."

Of course the L model had dive flaps which could prevent this from happening, but the flaps did this mainly by slowing the plane down in a dive.

[niklas]

wells, donīt you think 7400lb is a little bit too much weight for a G10? Nowarra says about 3400kg / 6800lb. Is it possible that your source added the weight for an external fuel tank?

Youīre right that the slower the plane getīs, the harder i have to pull to get 4G. I know that problem, nevertheless you can see the difference between those planes.

ok, induced drag is maybe a little bit lower for the P38. A little bit. But you canīt look only at a moment, at the moment of 300mph. While drag slows your plane down, your engine gives energy back, right? and the G10 has a much better powerloading.

Add the force of the engine to the negative force of drag at 300mph and iīm absolutly sure myself that the new deceleration is bigger for the P38.

niklas
 

[F4UDOA]

Where are you getting your CL data from??
Is it specific to the P-38L?