Author Topic: Bf109E4 vs c202 climb rates... (Read 960 times)

Blue Mako · « **Reply #15 on:** October 31, 2002, 12:08:24 AM »

Apples and oranges.

HoHun · « **Reply #16 on:** October 31, 2002, 01:02:31 AM »

Hi Blue Mako,

>Apples and oranges.

I can safely compare apples and oranges as long as I stick to facts and data - which I did.

So can you point out where my climbrate extrapolation is in error?

Regards,

Henning (HoHun)

Angus · « **Reply #17 on:** October 31, 2002, 03:02:16 AM »

If the AH modelling was correct, the C.202's superiority would have to come from the wing design. But how so? The 202's wing area is slightly more, 16.8 sq. m. against 16.1, however the plane also weights more. Well, the .202 has a rounded tip and the 109 a square one, that does make a difference. The wingspan of the .202 is somewhat more, 10.58 m against 9.87 m. Without a calculator, I can but guess whether the aspect ratio might be in favour of the .202.
Nevertheless, I don't think this all would add up to the .202 being such a superior climber.

gatt · « **Reply #18 on:** October 31, 2002, 04:40:15 AM »

Well, I understand everything but ... 202 performance data are there and they are real. Official 109E's data are available as well, I guess. So, everything you have to do is compare real data with AH's a/c performance.

dtango · « **Reply #19 on:** October 31, 2002, 12:49:40 PM »

I think what mako is saying is using weight and engine HP as a way to compare RoC between a/c is not very useful and pretty much comparing apples and oranges.

To appropriately compare you need to analyze the following relationship between the a/c.

RoC = (T-Di-Dp) * V / W

HoHun:

Your extrapolation only deals with the Dp portion of the equation (which btw is not linear as velocity varies). At airspeeds for best rate of climb Di has a much more pronounced impact on total drag.

Tango, XO
412th FS Braunco Mustangs

HoHun · « **Reply #20 on:** October 31, 2002, 01:09:56 PM »

Hi Dtango,

>I think what mako is saying is using weight and engine HP as a way to compare RoC between a/c is not very useful and pretty much comparing apples and oranges.

And what I'm saying is that I'm quite comfortable with comparing apples and oranges as long as I'm using adequate methods for the comparison :-)

>Your extrapolation only deals with the Dp portion of the equation (which btw is not linear as velocity varies).

Actually, my extrapolation deals with the total drag without dividing into parasitic and induced drag. I treated the all of the drag as parasitic drag only when I estimated the advantage of the C202, which is a simplification but works in favour of the C202 climb rate since ...

>At airspeeds for best rate of climb Di has a much more pronounced impact on total drag.

In short, I think we're not in disagreement at all :-)

That the C202's doesn't have the same engine as the Me 109's is obvious from the different gain going from MIL to WEP, which for the Me 109 is smaller below full throttle height and non-existant above that - in contrast to the C202.

In general, I don't think there's any reason to assume C202 and Me 109E-4 are using the same engine (or engine settings) in Aces High, especially as my quantitative analysis showed a performance gap for that assumption as well.

Regards,

Henning (HoHun)

dtango · « **Reply #21 on:** October 31, 2002, 02:01:59 PM »

HoHun:

Yeah, also just comparing the critical alts from the AH max speed charts does show that the AH C.202 and the 109E aren't using the same engine (maybe similar but definitely not the same).

Regarding apples and oranges - Mako is an aero engr. and I think he's voicing an unsaid sentiment that people should pay more attention to comparing performance appropriately as a general statement since seeing continual funky apples to oranges comparisons gets old

. I don't think this was directed toward your analysis.

Tango, XO
412th FS Braunco Mustangs

GRUNHERZ · « **Reply #22 on:** October 31, 2002, 02:10:47 PM »

Well if they arent using the same engine, or are not getting the same engine power they should be. The engine in the Bf109E4 and the engine in the c202 are identical. In fact many IRRC many c202 actually used DB made engines before the the Italian direct license build copy of the DB601-Aa got made.

So there. The very fact that they dont use the same engine or as you said dtango: " just comparing the critical alts from the AH max speed charts does show that the AH C.202 and the 109E aren't using the same engine (maybe similar but definitely not the same)." proves something is inaccurate with the AH Bf109E4 in the engine model department. They used the same engine with the same power.

dtango · « **Reply #23 on:** October 31, 2002, 03:44:59 PM »

Quote

...proves something is inaccurate with the AH Bf109E4 in the engine model department.

Grun: Nah, it only proves that HTC didn't use the same engine data in the flight models.

Tango, XO
412th FS Braunco Mustangs

GRUNHERZ · « **Reply #24 on:** October 31, 2002, 06:22:19 PM »

Then why does does HTC use a less powerful engine in the Bf109E4 than in the c202, when it historic fact that they used the same identical engine with the same identical output. Or do you doubt that the Bf109E4 engine in AH is weaker than the c202s engine.

dtango · « **Reply #25 on:** November 01, 2002, 01:44:48 AM »

Grun:

If we dissect this a bit more I think we find that we can't make the claim that the E-4 and the C.202 had the same engine. Consider the following:

Based on the load out of the AH 109E-4 we probably have the E-4/B variant. From what listings I could pull the E-4's and E-4/B's used the DB601Aa powerplant.

We know that early production C.202's were fitted with the DB601A-1.

We also know that this was only temporary until Alpha Romeo could build their own versions of the DB601A-1's known as the RA 1000 RC41 to fit into the C.202.

Interestingly enough if you reference Jane's Fighting A/C of WW2 it lists the C.202 with a DB601N powerplant (rated at 1200 HP, with 1270 HP with MW50 and 96 octane fuel).

So which engine do we have in the AH C.202- the DB601A-1, RA 1000 RC41, or the DB601N? On top of that none of these choices are the DB601Aa.

This doesn't even factor in which type of fuel the AH 109E and the C.202 powerplant performance data may have been based off of.

I think your question about the performance differences is a great one. The point I'm trying to make is there's more to the puzzle than meets the eye. Let's not be so hasty to jump to the conclusion that something's wrong with the flight model without some more thought about it all.

Tango, XO
412th FS Braunco Mustangs

SFRT - Frenchy · « **Reply #26 on:** November 01, 2002, 02:01:18 AM »

Huuuuuuuuuummmm ...

I know squat in German stuff, so pardon my question .... they may have the same engine, but do they have the same propeller too?

In P47s, the paddle blade gave 400fpm more climbrate to a heavier Thunderbolt.

kreighund · « **Reply #27 on:** November 01, 2002, 10:45:25 AM »

what about the He-100D-1 with the Db601M engine..wouldn't you like to be in one of those...top speed 416mph at 16400ft on 1100 hp...

HoHun · « **Reply #28 on:** November 01, 2002, 11:25:54 AM »

Hi Dtango,

>Based on the load out of the AH 109E-4 we probably have the E-4/B variant. From what listings I could pull the E-4's and E-4/B's used the DB601Aa powerplant.

I've found speed figures for the Me 109E that seem to coincede with the Aces High figures in "Messerschmitt Me 109" by Radinger and Schick. However, these figures are from the "Flugzeugdatenkennblatt Bf 109E-1/E-3" (L.Dv. 556/2) and accordingly apply to a DB601A-1 engined aircraft.

Interestingly, the climb times (no graphs are provided) give an initial climb rate of 3280 fpm however and a time to 6000 m of 6.3 min while the Aces High graph is equivalent to 6.7 min. (There's a comment indicating that the original data sheet numbers apparently have been rounded conservatively.)

>Interestingly enough if you reference Jane's Fighting A/C of WW2 it lists the C.202 with a DB601N powerplant (rated at 1200 HP, with 1270 HP with MW50 and 96 octane fuel).

That's highly interesting indeed! The C202 figures match the Me 109F-1 figures closely, even in the large gap between Climb & Combat and WEP climb rate. (Though the C202 weighs almost 500 lbs more than the Me 109F-1.)

There seems to be nothing that indicates which series the Aces High C202 belongs to, or did I miss it?

Regards,

Henning (HoHun)

GRUNHERZ · « **Reply #29 on:** November 01, 2002, 12:47:50 PM »

I have not read of C202 having a DB601N. The N component was GM-1 nitrous oxide boost used only at very high altitudes IRRC, the Bf109E7 with this motor could gain 70-80km/h speed with this boost at high alt. This was not used at low alts.

The AH Bf109E4 is not a B because it doesn't carry bombs.

The DB601-Aa (1175) is more powerful than the DB601A-1 (1100).

Everything I have read about c202 has said 1175hp, so that engine is like DB601Aa as in BF109E4.