F4u and etc. performance data

[Yentl]

Why is it that there is so much griping over the performance of flight simulation airplanes?  I ask this question because with the advent of the Internet the performance figures are not very hard to obtain.  I believe that Aces High and other flight simulations need to cite the source from  which they base the Flight Models.  This would make most of us including myself shut up.  It would also make other users who want to pilot realistically modeled WWII vehicles in combat against others aficionados very happy.  I think most of us fall into this category.   Why have I opened this thread??  Well I love the F4u and I tested it out online and offline and it doesn’t match the Bureau of Aeronautics Number flight data.  

BUNO #02153

Specifications:  
Vought F4U-1D Corsair - Carrier-bases, fighter-bomber  
Dimensions:  
Wing span:  40 ft 11 in (12.47 m)  
Length:  33 ft 4 in (10.17 m)  
Height:  16 ft 1 in (4.90 m)  
Weights:  
Empty:  8,694 lb (3,947 kg)  
Operational:  12,039 lb (5,465 kg)  
Maximum Take-Off:  13,120 lb (5,951 kg)  
Performance:  
Maximum Speed:  415 mph @ 20,000 ft (6,096 m)  
Cruise Speed:  182 mph (293 km/h)  
Climb Rate:  3120 ft/min   
Service Ceiling:  33,900 ft (10,333 m)  
Normal Range:  1,015 miles (1,633 km)  
Maximum Range:  1,562 miles (2,514 km)  
Powerplant:  
One Pratt & Whitney Double Wasp , 2,250 hp. R-2800-8W eighteen-cylinder radial engine.  
Armament:  
Six .50 calibre machine guns. External load of 2,000 lbs. (908 kg)
bombs or eight rockets.

In Aces High I had a Max Speed of 400mph @ 20000  with wep after 5+ minutes of acceleration.  Furthermore the Aces High F4u is unable to sustain a 3120 ft/min climb.  The climb data is based at sea level and I suppose that it would diminish as the AC climbs.  So it may be modeled correctly.  But the max speed is at least 15 mph off.  By the way the BUNO data is the lowest I found for this AC.  I found sources that said it did 425 mph @ 20000.  Basically tell us where you get your data so we can all shut up and enjoy this simulation.   By the way WWIIOnline concept is squeakin and it would be great if that is the future of Aces High.  I have been flying WB for some time now as Yentl and would love to see Hitech and Pyro succeed.  

[wells]

I agree with you on the climb rate issue.  I just made a post on AGW about this.  It looks to me like the climb rates in AHT and the pilot's manual are for best 'angle' of climb and not the best 'rate' of climb, at least for the F4u.  Those rates being 2700 fpm @ 135 knts IAS at a weight of 11700 lbs.  I believe a higher rate of climb of near 3200 fpm could be achieved at a slightly faster climb speed.  Pyro, I can send you my analysis and methods if you want to explore this issue further?  

[CombatWombat]

Using a single source of data has it's own problems as well.  First, where did the data origonate from?  Was it allied flight tests, possibly biased to boost moral?  Dash-1 manuals, which often contain inaccurate information?  Personally, I dont think you can make the aircraft fly right on the numbers, since everyone and thier aunt and uncle have thier own set of figures.  

I'm more concerned with, "does aircraft A perform correctly in RELATION to aircraft B".  I could careless if plane A should have a climb rate of 3100fps instead of 3150fps. As long as it outclimbs (or doesnt) aircraft B by an appropriate margin, then I'm happy.

BTW:  something I see wierd in all flight sims I've flown.....  Power on Split-S is abnormally small.  Check out the P47 training film at http://www.zenoswarbirdvideos.com/
It has something in there about power on, and power off split-s's.  

Now again, is the film wrong?  Or the sim makers?  Little of both?  Niether?  It's just too hard to tell.  

[indian]

They have more data then you can think of so you better have alot of proof before saying they are wrong.

------------------
Tommy (INDIAN) Toon
  Cherokee Indian
My Homepage
Where you can find the Key Commands in  files for Word6 Wordpad and text mode.

indians Homepage

Aces High Word6 and Wordpad Doc's available on my web site.

[juzz]

I got the F4U up to 37,000ft easily. Then I hit WEP and got up to 42,000ft. Ceiling of 33,900ft is given in the figures above. Where is it getting an extra 8,000ft from?

After the long climb, I then went into a dive. The F4U lost control effectiveness at around 600mph IAS. Trim tabs still effective. At 10,000ft, passed through 700mph IAS, on the way to ~730mph IAS at 7,000ft when I tried to pull up. Stick input was very ineffective. So I hit "x" and the autopilot pulled me out of the dive in a matter of seconds.

Now, I don't know for sure, but isn't 700mph IAS at 10,000ft supersonic?!

[Toad]

Juzz,

So what's yer point?
<VBG>

[Yentl]

First of all I didnt say anyone is wrong just that we use a data source that is respected and that the simulation producers cite the source.  Also I believe that if 1 respected source is used the planes will behave as they are suppose to.  The FW and all other planes will excel and falter where they are suppose to.  Oh and I believe his point is that planes without swept back wings or specialized airfoils would break up at supersonic speed.  I dont believe that the service ceiling is an unbreakable barrier but the altitude the aircraft can sustain without damaging the engine.

[Minotaur]

OK OK!  Beta Beta!

Mino

[juzz]

Huh? You have to have a point? Hmmmm, give me a minute...

OK, how about these:
1. F4U can climb too high. 8000ft over the "service ceiling" is surely way too much? Similarly, the B17G is getting to 40k+ too with a bombload.
2. Trim tabs always function very effectively at any airspeed.
3. Which leads to autopilot being able to do stuff like get you out of spins, "compressed" dives etc... autopilot takeoffs are possible in some planes.
4. I say "compressed" because the "Mach effect" isn't modelled, only higher control forces/lower control surface deflection as IAS increases.
5. Thus supersonic dives are possible without a)ripping the prop off, or b)ripping the airframe apart.
6. More off topic, but I think aileron trim is screwy. The Spit and 109 "run out" of aileron trim at high altitude and you can't fly level without constant stick input. Considering that Spitfires didn't even have aileron trim, it was set at the factory by bending the (metal) ailerons. Hmmmmmm...

[Yentl]

Ok I understand your "make a point thing".  The reason I started the thread was an effort to suppress the disagreement about performance.  If the programmers say " this " is the source we are using it would shut a lot of us up.  Those who disagree with the source are just being difficult because all the planes will fly "realistically" in comparison to the others if the methods used for testing are the same.  I know the next problem is the foreign aircraft might/will not be tested by the same labs.  Ill wait and see.   It is a beta but, my problem is not about the supersonic thing and not with the F4u in particular.   I think it would help if we could see the performance data they are using maybe, post it on the web page./

[Toad]

My "what's your point" comment was tongue-in-cheek. Sorry, I should have used the appropriate emoticon.

Juzz clearly has a point.

I also remember Pyro saying that the FM's aren't finished, so I'm patient at this stage of the beta.

Still, it's important that "anecdotal" evidence like "supersonic F4's" get reported so that Pyro and the crew can check into it.

I also have some problems with the trim modeling and how it affects aircraft "flyability" but I think this is going to fall into the "playability" category and don't hope for much change.

Anyway, I'll use ;-^ more often!

[This message has been edited by Toad (edited 12-05-1999).]

[Pyro]

On service ceilings:  First, I challenge anyone to cite two separate sources stating the F4U has a 34000 foot service ceiling.  Second, service ceiling like just about all other performance parameters varies with weight.  It's not a static property.  The lighter you are, the higher you can go and vice versa.

Wells:  It looks like you've discovered the F4U paradox.  It's plagued me for a long time.  I have a different take on it than you but I'd be happy to take a look at your analysis.

I have to disagree with the matter of 135kts being the best climb angle instead of climb rate.  It would make no sense to put a best angle of climb speed in the climb data chart, especially given that the chart goes up to 30,000 feet.  For what reason would a pilot ever want to use best angle of climb to climb to 30,000 feet?  Why would the climb data chart on the F4U be different from all other similar charts and yet not have the difference annotated in the remarks section?  Further, the British pilot's manual for the F4U states a best climb speed of 125 kts instead of 135 kts, but specifically labels it as "the speed for maximum rate of climb".  This information is reiterated in Eric Brown's _Wings of the Navy_.  AHT cites a best initial climb speed of 144 mph which corresponds to the British manual's 125 kts.

In _Whistling Death: The Test Pilot's Story of the F4U Corsair_, Vought test pilot Boone Guyton does mention carrying out a climb test at 130 kts IAS but doesn't give details.  He does state that the calculated climb performance on the F4U-1 was initially estimated at over 3100 fpm and on the F4U-4 at over 4000 fpm.  The actual performance figures he does cite correspond closely to those given in AHT under emergency power.  

The discrepency that you're finding is one that I think can be attributed to the propeller's characteristics.  I think the F4U suffers from the same problem that the P-47 did prior to the implementation of a paddle bladed propeller.

If you look at the performances given in AHT, it does bear this out.  While the F4U-4 is generally known for its more powerful engine, it also changed to a better 4-bladed prop.  If you take a look at the weights and performances given and make some HP calculations, you'll see that the added HP of the R-2800-18W cannot solely account for the performance differences.  Aerodynamic differences also couldn't account for the difference in climb rates without having a much larger effect on differences in top speeds.

Another interesting item is that the F4U-1D changed from the 13'4" prop to a 13'1" prop starting with BuNo. 57356 and from BuNo. 76149 on the FG-1D. I don't recall other accounts of this or the reason and effect that it had.  



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

[Duckwing6]

How about looking in the ORIGINAL Pilot manual foks.. there is no much sense in looking at 200 different accounts from test pilots and stuff.. there
s gotta be a pilots manual for that plane (all US iron should have that pretty easy to find .. not talking about LW, or IJN planes).
I don't know if i have the "original" POH but there is a reprint available ISBN0-87994-026-3.
This one states:
135 KIAS for best combat climb at all gross weights up to 10.000ft and then on with 130 KIAS up to 20.000ft .. and so on ...
well regarding service ceiling.. that is totalz useless to be counted as a "total limit" because it's NOT! its depending on weight, atmosperic conditions and oher factors.. so most handbooks in modern aircraft state a service ceiling.. but this one can be easilz exceeded when not a max gross weight.

Phil "SC-Duckwing6"
The Skeleton Crew

[wells]

I was thinking the same thing about the propellers.  On the prototype F4u (and P-47), the engine was rated for 1850 hp, right?  So, I was thinking that the original propeller was probably designed for that figure and wasn't upgraded until later on down the line.  So although the early production models were producing 2000 hp, the prop was only giving about 1850's worth of thrust?