Macchi C.202 performance

[gatt]

PYRO,

I say the C.202 is slow becouse last time I checked her performance she was barely able to reach 350mph at 18,300ft (with no WEP). Just 8mph more than an Hurricane MkII.
Again, my only reference are the data you already know. As far as the climb rate is concerned I'll send you something.

SORROW,

my Lavochin data tables (from Gordon-Khazanov book) say that the production La5-FN get 385mph at about 20,000ft. This an old topic: we should not have prototype data.
About C.202 real performance, our pilots found her superior to Hurricanes MkII and P40s (armament apart). Very similar to the SpitMkV in speed and climb rate, not in turning abulity. IMHO the C.202 should not out turn the Spitfire, due to Macchi's good speed, heavy weight and wing load. But again, I'm not an engineer so I can be probably wrong.

About Buerling .... yes, he was an outstanding ace. We all know how he considered his italian and german foes: like meat to butcher. So I am not going to comment his memories at all. An old friend of my family fell in battle under his cannons over Malta. When I red what "Screwball" had written about it, well ... I felt sick.


[This message has been edited by gatt (edited 04-20-2000).]

[leonid]

 

my Lavochin data tables (from Gordon-Khazanov book) say that the production La5-FN get 385mph at about 20,000ft. This an old topic: we should not have prototype data.
- GATT

The problem is that no other country besides the USSR kept such scrupulous data on their production aircraft!  All the data you see in book and used in flight models for USA, UK, Italian, Japanese, and German aircraft is prototype data!!!

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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 04-20-2000).]

[Vermillion]

Exactly Leonid, this has been my contention for a long time.

We don't see performance for war weary P-51's, P-47's, Spitfire's etc. The numbers we see for them are either the prototypes, or specially maintained test aircraft.

But the Japanese aircraft (especially late war planes) are perpetually hampered by 85 Octane avgas, with pine tree oil boost additive.

The Germans, by FM's based on captured intentionally de-tuned war rated engines (for longer in-service periods I guess), or just plain worn out war weary aircraft.

And the Russians with "average" aircraft from the productions lines, because they actually kept such records, instead of the pristine highly tuned test aircraft.

I think it would be great if we got an even basis for what kind of tests on what condition aircraft are used for the FM's.

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Vermillion
**MOL**, Men of Leisure
Carpe Jugulum
"Real Men fly Radials, Nancy Boys fly Spitfires"

[gatt]

Dont get me wrong Leonid, I'm happy with your La-5FN.

For some good italian fighters, like the G.55 "Centauro" and the Re 2005 "Sagittario", we have both prototypes and production variants data.

What I cannot understand is why official data (the data shown are from production C.202 models, IV-VIII series that is) and AH FM can differ so much.

[v-twin]

SORROW:

The italian Army was (and is more or less still today) accustomed to reveal NOTHING about the equipment, techical data were absolutely secret.
The fascist propaganda never cared about technical data (it would have been self-defeating!   ), used more spectacular means.


LEONID:

hey!     no reason to become angry
AFAIK all the available data comes from the evaluation test of the Air Ministry.
If you check, every source reports the same data.
Moreover, it could be possible that that data are a little conservative: consider for example the Mc205, his ratified max speed is 642km/h, wich was the worster max speed reached during the test.
It seems therefore that the Air Ministry used to consider not the best value obtained but when not the worster, at least an average value, maybe in order to have a kinda of "minimal guaranteed performance" of that AC.
But this is only a thought.

v-twin

[Sorrow[S=A]]

V-twin:
Yes, I did not mean propoganda for others, I referred rather too the fact that often the tests are skewed for political reasons by the  producers. In the case of the La, the odds are high that prototype stats were bumped and massaged to make it look as good as possible against the Yak, whose maker had more political connections. The data for the "standard of 1944 La-5FN" is ridiculous. The plane was never a production and never fought, yet it satisfied the stats required to produce the La-7 and so were submitted. Odds are high that in the struggle between Fiat and Macchi figures on both sides would be massaged to make the RA want their fighter produced instead.

Leo: Preach on comrade, I hope the La-7 reflects the stated numbers closer than the La-5FN does.

Gatt: yep, Buerling was a sweetheart. We breed them like that in Quebec <runs and ducks for cover>. But my point here is what you STATED YOURSELF. The .202 should behave remarkbly close to a Mk V spit, the stats you want are waaay out of line with that. Your stats would get it rocketing at lower alts and outrunning it like mad. This is out of line, perhaps the plane needs tweaks in climb and especially speed (I agree she is dreadfull slow) but I cannot see the .202 behaving like your stats rate her. Climbing at 5000 FPM???  Everything I read indicates she was lacking in power thus the .205 upgrade to the german motor.

I really do agree she shouldn't be spinning circles about spit's tho   I didn't know she could, I never do anything but yo'yos  in her.

[This message has been edited by Sorrow[S=A] (edited 04-20-2000).]

[gatt]

Yes SORROW,
if you read what I posted you can see that from the official data we have and how the AH C.202 behaves theres TOO MUCH difference.

Is 6 minutes to get to 20,000ft a ludicrous figure? Well, IMHO, 7'15" is unreasonable as well. Are 373mph at 18,300ft ludicrous? I dont think.

I have digged out the official manual of the Reggiane Re 2001, a nice fighter that fought over Malta side by side with the C.202. She mounted the same license built DB601A of the C.202 and weighted some 680 lb more. Well, her time to altutude are the following:
Time to 13.120ft: 4'10"
Time to 19,685ft: 6'30"

Ludicrous data? Who knows. The official B17 flight manual data allow our AcesHigh B17 to turn fight at 30,000ft+ with fighters. Does it tell anything to you?

[leonid]

gatt & v-twin,

I'm not really angry, just a little frustrated  

So many people have seen the books where two sets of data are printed for VVS aircraft: prototype and production.  In most books for aircraft from other countries like Germany, USA, or Japan, you will usually see only one set of data.  I think many people assume that this data is production data when it is actually prototype/test data.

I almost wish that these new books on VVS aircraft never put out the production data, just to prevent all the misunderstanding.

But, no, I'm not really angry.  See? ->  

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leonid, Komandir
5 GIAP VVS RKKA

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

[v-twin]

SORROW:

Fiat & Macchi couldn't do absolutely nothing to let RA choosing their fighters.
They could give the RA all the possible data, but only the results of the evaluations test of the Air Ministry (on production AC, not on prototypes) were valid for the choice.
But that was not a big problem and the factories knew that: in fact all the three fighters, Fiat G55, Macchi Mc205, Reggiane Re2005 were accepted 4 the production (even if in different numbers), because all the three factories had "contacts" in the RA...
As for the performances, nobody here said the 202 outmaneuvered the Spit V: the performances were almost equal (same speed, same maneuverability) but with a clear advantage 4 the 202 in climb ability and maybe acceleration.


LEONID:

The problem is that the data of the Air Ministry aren't of prototypes: the test 4 the choice were led, as usual, on AC which were ready 4 the series production and combat ready (full fuel & ammo).
The only data of a prototype I know is the climbing time of a "prototype" of the 205, wich I assume was a 205 whitout armamament or at least only with the 2x12.7mm in the cowling: 4'40" (more or less, don't remember exactly) up to 6000m, where the production 205 climbed in 5'30".


In general, I think we trust too much the mathematical calculations.
The behaviour of an AC is affected by a huge amount of variables and only few of them are knowed.
We can't say too much about an AC only knowing weight, power, dimensions and so on.
Who knows the exact position of the CG of an AC (remember the WB 190...), what do we know about the wing contour, the aerodynamic drag, the inertia etc etc etc...
Yes we can roughly estimate some parameters, but we can't get an accurate sim only starting from the available data, regardless of the AC we are speaking about.
Therefore if the sim can't match the available data of an AC, I think we have to ignore what the sim says and put the data in the FM.

v-twin

[wells]

So you are saying, make the 202 weigh 5000 lbs fully loaded, give it 1400 hp and do not calculate induced drag and ignore any drag that the propellor makes, just so it matches some performance figures?  There are laws in physics.  It's highly more probable that the performance figures cited are not correct, rather than the physics being wrong.  Personally, I believe those figures came from 'somewhere' and there is a reason why it climbed so well.  I think it has to do with engine power!  The engine was putting out much more than 1100 hp in that flight test, but only the 'official' rating for the engine is given.  Whether it was a conversion to DB601E or it was a 605A engine or some super high octane blend fuel was used, or the flight took place on a nice cold day and the results were not corrected for 'standard' atmosphere, I don't know, but it's not impossible for that to be the case.

[Vermillion]

Physics?? Damn... you actually believe that crap Wells ?  

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Vermillion
**MOL**, Men of Leisure
Carpe Jugulum
"Real Men fly Radials, Nancy Boys fly Spitfires"

[Kieren]

v-twin

The problem with selective application of physics is that it removes the one standard we can rely on for high-fidelity flight models.

You may or may not be right on the 202. I wish it climbed the way my book says it should (and I do fly the thing). I am however satisfied that, even though my bird du jour doesn't perform the way my data says it should, it is for the greater good not to tweak it without hard physics to back up the adjustment. The ramification is that you would have anecdotal data as the basis of fm, and that shouldn't happen IMHO.

[ra]

I didn't want to be the only one not posting to this thread.

[v-twin]

Again: we are not talking about "anedoctal data", we are talking about tests performed by the Regia Aeronautica on first serie's machines.

A simulation, as the name says, simulates the behaviour of a certain *thing* taking in account a set of data and relationships which we say are sufficient to explain this behaviour. So the output of a simulation in general won't match 1 to 1 the reality, it will come as close to reality as much as the data and relationships taken in account are sufficient to fully explain the behaviour we are investigating.

Measured data say that the MC202 had a certain kind of climb performance given the DB601A (same as BF109E). The simulated performances are far away. IMHO in such case, when RL data and simulation are different, we should take the RL data. I don't say that the FM is crap: I just say that, since it is a simulation, by definition it is an approximation to RL and IMHO it cannot substitue RL if test data are available (doing my job I often have to deal with this kind of problem). I don't know that much about relevant variables involved in AC-simulation, but till now we only discussed about engine power, weight, aspect ratio and wing area.
Maybe there are other relevant variables such as aerodinamical aspects of the frame and/or wing profile a.s.o. which are too complicated to take in account and/or unknown, but which could make the difference.

IMHO in front of such a difference between simulation and RL data we have to investigate why there is this difference. In this case I personally think that the Regia Aeronautica had the means to perform correct test the same as other airforces could do at that time, so it is not that easy IMHO to simply say "the data are wrong" without going any deeper.
This is obviously valid in general: if RL data are available they should come first than the simulated one.


v-twin

[wells]

v-twin,

I agree with you that we should find out why there is a difference (in fact, it's really bugging me now!), but I don't necessarily agree that flight test data should take priority.  Take the Navy data for the F6f and F4u-4 as classic examples.  The F4u-4 climbed at 4700 fpm in that test, when other sources say about 3900 fpm.  So why the discrepency?  In the test, they point to the use of 115/140 grade fuel, which allows the R-2800 to produce some 2800 hp.  So should every F4u-4 modelled use 115/140 grade fuel because of that one test flight?  In the case of the F6f-5...It climbed at only 2950 fpm, when other sources point to 3400-3600 fpm climb.  In that particular test, the engine was deemed to be producing only 2030 hp for combat (only 30 hp more than the MIL rating and the official rating is 2250 hp for the engine) and the plane was carrying 20mm weapons, making it a few hundred pounds heavier, but some sources don't say that!  I fully agree that the numbers for the 202 came from somewhere and look to be very legitimate, but not all is known about that flight.  There is a discrepency somewhere...either in HP rating for the engine or loaded weight of the aircraft or octane rating of the fuel or something else that is not mentioned at all.  Until that missing link is known, the data should *not* be used to make the model.  The theoretical model is probably better for 'simulating' the average aircraft, where some may have performed better, some worse.