Macchi C.202 performance

[gatt]

THX all for the replies. I for one will not fly with a kite some 20-25mph slower than the real thing and that climbs at 2,700ft/min (average), like a brick that is. I mean both in main arena and during scenarios. She has not her historical strenhgts against Spitfire Vb and P40. I dunno what other squaddies will do, I know for sure which hint I'll give them.

From a sad Macchi driver
4°Stormo CT
"F.Baracca"

[This message has been edited by gatt (edited 04-18-2000).]

[v-twin]

Hi Pyro, something is not clear to me: you can't make the "real" 202 because the FM doesn't work with that set of data or because calculations gives different results that don't match the data?


v-twin

[Dinger]

Maybe I can add to the confusion:
We're not dealing with "pure" engineering data representing some Platonic ideal plane, but rather with historical data gathered (or not) from a determinate existing aircraft.  That means that they are subject to all kinds of possible perversions.  It also means that no two sets of tests are going to agree completely.  The end result is that building an appropriate FM becomes a matter of interpretation and, yes, guesswork.  So anyone who claims a 100% faithful FM doesn't know what they're talking about.
Some of these corruptions of the data come from the equipment tested (say, a captured 109 with seriously degraded engine performance), the pilot (an inexperienced jockey or a seasoned professional), the conditions on a given day (ok, who went testing the thing in the eye of a hurricane), the purpose of the test (to sell the product, to find out about its capabilities), and simple manuscript errors (ever read the story in Primo Levi's The Periodical Table about how a flunky chemist in WWII's careless mistake in copying resulted in a change in the paint plant's chemical formula that lasted 25 years?).
That being said, the 202 climbs like a DOG! Clearly the 39 seconds is a minor error -- they meant 49! Some of those manual numbers gotta make sense! Fix it ASAP!

[wells]

If you look at Green's data for the type, (apparently from the same source) you will see a 1400 hp figure (not mentioned in the Air Mininstry source).  If somehow, the engine was producing 1400 hp at sea level, then the climb performance noted makes good sense (Perhaps a prototype for the 205?). Otherwise, no more than 17.5 m/s could be expected from 1100 hp.

[gatt]

Wells,

Green mistook the C.205 for the C.202. A lot of books written by UK-US writers do it. Moreover Macchi's never mounted a 1,400hp engine. What can I say?: that 2,700ft/min (average) to climb to 19,700ft is clearly wrong.

We have seen the same thing in the AH C.205 for a couple of months. The first C.205 never exceeded 3,000ft/min during her climb, a real dog. Then she had a very good 3,500ft/min average climb rate, no-no-no said all the people. And then she was tweaked down above 15,000ft.

Does it tell anything to you about the need of continuous FM fine tuning? Anyway we wait with faith, at least for some months more  

[wells]

Gatt,

Green did not mistake the 202, he has the same data as your Air Ministry data for the 202.  If he did mistake it, there is a good reason...cause the numbers make no sense for an engine that only put out 1100 hp or so.  What data do you have on the 205?  How does it compare for climb and weight?  Does it make sense when compared with the 202 data?

[gatt]

On the C.205 there are no performance data around. Not even our best historians have anything. I sent the only data tables (about C.202 and C.205) I have ever seen to PYRO.
They have data, about the C.202, very similar to those I posted above.

Again, a 1,400hp engine had never been mounted on a C.202. Yes, the first C.205 ever tested (and a lot of others, due to C.202 parts already built) was a C.202 with a DB605A1. But it was tested as a C.205.

I dunno if the data tables we provided make sense, I dunno if the FM used by PYRO always do the right work.
All I know is that the C.202 we have is no way similar to the real one (and we italians have red tons of books about the Folgore). But again, what do we know?  

[wells]

yeah, I haven't seen too much on the 205, except a 399 mph top speed and that it used the 1475 hp DB605A engine.  What I think we really need to do here, is compare to a similarly powered 109.  They really should be very similar, especially in climb.

The similarly powered 109E could manage 17-18 m/s and it weighed 1000 lbs less, albeit a tad draggier.  The 109F is closer for weight and speed but it needs 1350 hp to achieve the kind of climb rate that you are talking about.  Could it be possible that the 202 in question used a modified engine to bring it up to 601E standard?  There *has* to be a reason for it's good climb...

[This message has been edited by wells (edited 04-19-2000).]

[leonid]

I know this is late, but high aspect ratio means long, thin wings, and the longer they get the slower they roll.  That's one disadvantage, niklas.

------------------
leonid, Komandir
5 GIAP VVS RKKA

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

[F4UDOA]

Also a high aspect wratio wing does not provide the General maneuverabilty and and tight turning radius that a low aspect ratio will. Aerodynamics are a trade off. Go with a long thin wing and you get a lot of lift and long range IE. the Voyager one man vehicle that tried to fly across the earth a couple of years ago. But you sacrafice tight turning ability and rate of roll, as well as the ability to pull up from high speed dives into compressabilty because of structural weakness and the way shock waves build up on a narrower wing. A wider wing buys you more times to deal with the loss of control. Just look at the contrasting performance of the F4U vrs the P-38. One of the lowest vrs one of the Highest. The P-38 needed range and the F4U needed maneuverabilty. Any flight test data from WW2 would bear this out.

Thanks
F4UDOA

[v-twin]

From what I read, it seems the resons 4 the excellent perf in climbing and maneuverability of the Macchis were the perfect aerodynamic and first of all the wing.
Dont'know exactly wich was the "secret" of the Macchi's wing, unfortunatly I never was able to find a anything with a deep descritpion of the wing.
It seems that the profile and his developement in the lenght of the wing were something particular.
Probably the result of all this was a really low drag and therefore better performances by same engine power.
The Luftwaffe did a test comparing Bf109G4, Fw190A5, Fiat G55, Mc205, Reggiane Re2005 and found the 205 climbing with the 109 and maneuvering better (among other things, LW said the 205 required less power in the turns than the 109, dunno exactly what that means).
Jg77 used the 205 in winter '43, judging it as excellent.
It must be said that Mario Castoldi, the designer of Macchi, was an excellent engineer, he had a long experience in designing race planes (the Macchi M39 which won the Schneider Trophy in 1926 and the superb seaplane Mc72, wich reached 711km/h, world record 4 seaplanes) and knew very well how to deal with aerodynamic, wing profiles, drag etc.
The Mc20x serie were the masterpieces of Castoldi.

v-twin

[gatt]

Hehe, V-Twin ...  
The MC72 Speed World Record is still unbeaten:
 

The sky is covered and the weather begins to change only after 1:00 P.M. At 1:50 P.M. everybody takes his place and the pilot gets into his plane. At 1:56 P.M. He takes off after an interminable run up. Visibility is far from excellent. For turnnig Agello takes the Montichiari church dome as orientation point. With a baffing speed of 709 km/h he makes four passes and establishes a record that will never be beaten by any seaplane with piston engine. One has to wait August 7, 1961 before the Russian Nicolaï Andrievski does better with a jet seaplane...

 

[Pyro]

I don't know what you mean by it being too slow.  Give me some numbers.  

On the climb stuff, let's put the shoe on the other foot.  Make me a climb chart and let me analyze mathematically what you think it should be.



------------------
Doug "Pyro" Balmos
HiTech Creations

Perfect plans, aren't.

[Sorrow[S=A]]

Gatt: is it possible you are falling into the "propoganda" trap?

One of the things that is odd in AH is that planes tend more to "realistic" than "historic" performance. My example would be the La-5FN. Historically she was claimed by almost all publications as a 400 mph fighter.
However that is almost ALL based on test flight data submitted to the war ministry. Often this data is manipulated for political reasons and is in the end only a rough guide to the actual plane. In the La-5FN's case I think pyro ignored that info and averaged the results of the extensive quality check information done in the field for his information. thus our fighter only does about 390-95 mph instead of it's touted 400.

In this case his figures on the .202 must be suspect, he has said so MANY times now. This leads me to believe there is a great deal of misinformation on the plane. Pyro has always been pretty reasonable about these things and giving explanations, it is my belief that if you supply quality information to him he will work those results into the FM.

  One thing that DOES pester me though, is that while the italian pilots never complained much about the .202's performance if it DID accomplish the feats your claiming it did why didn't the spit pilots on malta remark more about it? Buerling is one of my favorite topics and so is malta, especially the early stages of it. Nowhere have I read that the spit pilots in MkV's considered the .202 to be comparable to their planes. In fact in his diaries Buerling recorded 2 instances of being able to outloop one trying to escape from him. Is there a possibility that some of the information your basing your hopes for this fighter on are suspect? I think if the .202 climbed like your asking for Spit pilots would have had much more respect for it than they did.

[F4UDOA]

Pyro,

Correct me if I am wrong but the calculation for climb is mapped on a graph in two curves. One representing the horsepower required to fly a certain speed in mph and the second curve being the total horsepower available at that altitude in feet required to fly at that speed. The space between those two curves is maximum climb in ft. All other factors are accounted for secondarily in the horsepower required for speed curve.

Which brings me to my question when these factors are calculated how does prop efficiency get represented? Since usually you just assume they are working at 80% efficiency. Explain how this would work for the P-47D before and after the paddle blade prop if you don't take into account the activity level of the airscrew?

Bewildered
F4UDOA