Bf109E4 vs c202 climb rates...

[GRUNHERZ]

Here we have two airplanes with an identical engine (DB601A), the same horsepower 1175hp. lets compare their climb rates..


The Bf109E4 weighs 5875lbs.

The c202 weighs 6459lbs.


What the hell is going on here?

[GRUNHERZ]

c202:   1175hp DB601A 6459lbs

[GRUNHERZ]

Bf109E4:  DB601A 1175hp 5875lbs

[HFMudd]

Better aerodynamics on the 202 than the 109E maybe?  Perhaps the 202 does not waste as much energy just pulling itself through the air.  Airflow through the radiator might also make a large difference.

[HoHun]

Hi Grünherz,

>Here we have two airplanes with an identical engine (DB601A), the same horsepower 1175hp.

1175 HP is the take-off power of the DB601Aa engine.

In the DB601A-1 engine, take-off power was 1100 HP at 1.40 ata, and it was cleared for 60 s only, enforced by a clockwork timer.

(Judging by the somewhat generic Aces High WEP code recently posted here, I'd say this 60 s power setting is not modelled at all.)

5 min Short Duration Power (as it was called at that time) was 1000 HP at 1.30 ata. It might have been a bit more for the DB601Aa as it seems to have been cleared for 2500 rpm vs. the A-1's 2400 rpm.

I was told the MC202 performs better than the Me 109E-4 because the Alfa Romeo engine provides more power than the DB601A, presumably because it benefitted from experience with later DB601 versions. I don't know if this is correct, though.

Regards,

Henning (HoHun)

[GRUNHERZ]

The Bf109E3 had the DB601Aa, so the E4 had at least that model motor.  

You are correct though the DB 601A-1 had 1100hp but that was only used on the earliest Emils, the E1.  The E3 got the DB601Aa.

The E4 had at least the 1175hp.  The c202 also had 1175hp DB601.
 
And why is the WEP increase in climb rate about double (500fpm vs 250fpm) in the c202 over Bf109E4?

[HoHun]

Hi Grünherz,

>The E4 had at least the 1175hp.  The c202 also had 1175hp DB601.

The problem is that I don't have the exact ratings for the DB601Aa, but I guess it only differed from the A-1 by higher emergency power.
 
>And why is the WEP increase in climb rate about double (500fpm vs 250fpm) in the c202 over Bf109E4?

Good question! Since the C202 also benefits from WEP above critical altitude while the Me 109E-4 does not, I'd say the C202 increases RPM for WEP while the Me 109E-4 does not.

Regards,

Henning (HoHun)

[GRUNHERZ]

The c202 and Bf109E4 used the same engine with same 1175hp, so the vast climb performance advantage and double WEP climb increase are simply incredible considering the c202 weighs 600lbs more. Why is this so?

[Urchin]

If I had to guess I'd say the C202 climbs better because it is cleaner aerodynamically than the 109E.  I don't know all the scientific stuff, because part of my brain already exploded trying to learn it and I want to keep the rest, but I do know that the more drag an airframe has, the less lift the wings can give it for climbing with.

[Seeker]

It's all part of the Axis conspiracy!

No, wait..

[Staga]

Looks like Bf109s air-resistance value is bigger than Macchi's; check their top-speeds.

Fv = ½ s  A Cv

Fv = resistance power
s = air density
v² =speed²
A = frontal area
Cv= shape multiplier (planes had about 0,14-0,15)

Well that can't be the reason, Looks like both planes frontal profile is pretty much similar...
Maybe wing's profile? hmmmm... I don't think so.

[Staga]

Just made a quick calculation:
With same air-frame and Cv value it would take about 17% more power to get plane's speed from 350mph to 370mph which would be about 180hp in this case.

Maybe Macchi was cleaner design?

[GRUNHERZ]

Im sure the c202 has some advantage because of its slightly lower drag, though the c202 isn't exactly clean itself.  However drag alone doesnt make enough sense when its such a huge difference of 500fpm, at appx 3000fpm non-wep this is some 20% greater than the Bf109E4 nonwep, while the c202 weighs 600lbs more.

And none of this explains the double wep climb increase of c202 compared to Bf109E4, c202 gets 500fpm increase while Bf109E4 gets only 250fpm increase with the same motor.

What is going on here?

[HoHun]

Hi Staga,

>Maybe Macchi was cleaner design?

That's certainly not the answer, simply because the total power needed to overcome drag is quite small in a climb.

The Me 109E-4 has a top speed of about 345 mph according to the Aces High charts, compared to about 380 mph for the C202.

If both had the same engine, this would mean that the Me 109E-4 has 33% more drag.

However, climbing at 3100 fpm, the Me 109E-4 needs only 250 HP to overcome drag, while 750 HP are invested into climbing. For the MC202, the drag would be lower at 190 HP, but that would mean only 60 HP are gained for the climb. However, the C202 is heavier as well, and accordingly, climb would actually deteriorate.

(I made the calculation for 1000 HP and 75% propeller efficiency, but the results don't vary much if you use for example 1175 HP and 80% propeller efficiency. The C202 will climb better then, but will still be far short of the 3600 fpm indicated above.)

I don't think there's any way the C202 can have the climb rate advantage indicated by the above charts if it doesn't get more power from its engine than the Me 109E-4.

Regards,

Henning (HoHun)

[gatt]

These are data coming from papers of Ing.Castoldi himself:

http://www.hitechcreations.com/forums/showthread.php?s=&threadid=60673