Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: GRUNHERZ on October 29, 2002, 10:32:16 AM
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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?
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c202: 1175hp DB601A 6459lbs
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Bf109E4: DB601A 1175hp 5875lbs
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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.
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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)
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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?
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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)
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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?
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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.
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It's all part of the Axis conspiracy!
No, wait..
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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.
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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?
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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?
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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)
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These are data coming from papers of Ing.Castoldi himself:
http://www.hitechcreations.com/forums/showthread.php?s=&threadid=60673
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Apples and oranges.
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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)
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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.
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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.
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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
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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)
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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
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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.
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...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
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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.
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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
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Huuuuuuuuuummmm ...:confused: 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. :D :cool:
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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...
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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)
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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.
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Grun:
(1) The AH 109E-4 carries a 250kg bomb no? At least that's what's posted on for the E-4 on the AH website.
(2) I didn't claim that the DB601Aa isn't slightly more powerful than the DB601A-1.
HoHun:
Hmmm, I didn't think to compare to the AH 109F-4 model. DB601N engine. Very interesting indeed in terms of performance comparison! Have we found our C.202 engine? :)
[EDIT: Oops! The F-4 has the DB601E so scratch that comparison. Still very interesting about what you've indicated with the F-1 DB601N data you have.]
I have no clue as to which C.202 series the AH C.202 belongs to.
Tango, XO
412th FS Braunco Mustangs
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Hi Grünherz,
>I have not read of C202 having a DB601N. The N component was GM-1 nitrous oxide boost used only at very high altitudes
You're thinking of the Me 109E-7/Z (also referred to as /NZ). Though this aircraft used the DB601N engine, the Z stood for the GM-1 injection while the N alone stood for a DB601 variant running on 96 octane fuel. The DB601N due to a higher compression ratio had a greater full throttle altitude than the DB601Aa which it replaced in the middle of the Me 109E-4 series (creating the E-4/N). The DB601N also permitted 2600 rpm compared to the DB601Aa's 2500 rpm and the DB601A-1's 2400 rpm.
>Everything I have read about c202 has said 1175hp, so that engine is like DB601Aa as in BF109E4.
After a bit of searching, I've found the following two engines mentioned for the M.C. 202 (and I wouldn't be suprised if there were more):
RA.1000 RC.41-I Monsone
RA.1000 RC.44-Ia ("DB601Aa")
Though the Italian document where I found the latter designation refers to the engine as DB601Aa, the power table shows it's only run at 2400 rpm like the DB601A-1 even in one-minute power. Since the document refers to a M.C. 202 with two machine guns only, it must be for a relatively early aircraft.
(From what I've read, there were 12 series of M.C. 202 fighters, with series VI introducing the wing guns featured by the Aces High M.C. 202.)
I have been trying to identify the stencelling on the Luftwaffe-style triangle on the port fuselage just aft of the cockpit, but the photographs I found are too small to make it out (if there's any at all). From the photos and colour profiles, I'd think the triangles were either red or yellow, indicating the use of different fuel types, but that might be an illusion due to poor colour reproduction.
Regards,
Henning (HoHun)
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In flight and maintenance manuals of the C.202 and Re2001 fighters I've found references to RA 1000 RC 41 Ia, RA 1000 RC 441a and RA 1000 RC 411 engines. Output ranged from 1.075hp to 1.175hp (usually at 2.400rpm and in one case also at 2.500rpm) at take off.
You may have to consider also differences between the propeller used by germans and the one mounted by italians (the PIAGGIO P.1001). Moreover, the C.202 manual says that the engine could be pushed up to 1,45ATA at 2.400rpm with the propeller set at the so called "supergiri" (something like "superRPM").
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Hi Gatt,
>In flight and maintenance manuals of the C.202 and Re2001 fighters I've found references to RA 1000 RC 41 Ia, RA 1000 RC 441a and RA 1000 RC 411 engines.
Are you sure that -441a isn't actually -44 Ia? This looks like a mistake that would be easy to make. And it would reduce the engine variety we have to reckon with markedly :-)
>Output ranged from 1.075hp to 1.175hp (usually at 2.400rpm and in one case also at 2.500rpm) at take off.
The problem seems to be that the DB601N wasn't actually rated for more take-off power than the DB601A series, but could maintain higher continous power and had a greater full throttle altitude. We can't tell which engine was used from the ratings alone, especially as Alfa Romeo seems to have rated the engines slightly differently than Daimler-Benz. If the manuals list the octane rating, this would be more helpful for determining whether the DB601N was used.
>You may have to consider also differences between the propeller used by germans and the one mounted by italians (the PIAGGIO P.1001).
The difference we're observing is too large to be explained by a new propeller alone. Have a look at the Me 109F-1 - it achieved the same performance as the M.C. 202 on a VDM propeller. Even better, the Me 109T-2 with 200 kg of additional carrier equipment climbed at 3350 fpm with the DB601N running at just 1.25 ata. It's really the engine, not the propeller that makes the M.C. 202 so good.
>Moreover, the C.202 manual says that the engine could be pushed up to 1,45ATA at 2.400rpm with the propeller set at the so called "supergiri" (something like "superRPM").
That sounds like a misnomer if the normal 2400 rpm were used :-) I assume the 1.45 ata rating was cleared for 60 s only? That would be normal DB601Aa power.
Regards,
Henning (HoHun)
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* smack! punt! *