F4u climb rate ?

[wells]

DOA,

Think drag, not lift.  The drag coefficients you gave are only good at high speeds, where you can't climb too good.  I bet the drag coefficient on the F4u at climb speed is about 0.04.  A high aspect ratio reduces the induced drag, which is greatest at slow speeds.

[joeblogs]

F4udoa:

After sending my last note, I thought, Blogs the F4u-1D has the R2800-20W and that means 2250 HP.  

Are you sure the F4u and F6f have the same airfoil?  Seems to me a different aspect ratio should almost certainly imply a different cross section.  Even so, the two wings are set at a different angle of attack..

Other advantages of the F4u -- the gull wing lets the wings meet the fusalage at right angles, which some engineers argue is more aerodynamic.  The wings are smoother too - spot welded in front and fabric covered in back.  

I hope you tell us when your site is back up.  I am very much a collector of aviation materials and I am always looking for more.  What do you regard as your best finds?

-Blogs

JoeBlogs,

The F4U is on area that I have more information on than anyone I have ever spoken too, including Pyro. I have many Vought original Docs, Flight Manuals and countless others.

The F4U HP.

F4U-1 early 2,000HP
F4U-1A early 2135HP
F4U-1D and late -1A 2250HP
F4U-3 with supercharger 2800HP
F4U-4 2450HP
F4U-5 2800HP
AU-1 I need to look at my books. The rest is from memory. I am not in my library right now.

Anyway I am sure I will post the docs shortly. [/B][/QUOTE]

[F4UDOA]

Wells,

I thought Cd was constant? I know Cdi changes with speed but shouldn't the A/C with the lowest Cd climb better than one with higher drag such as the P-38? If the drag of the F4U is .04 at high AoA what is the P-38? They both have the same airfoil and the 38 has two engines nacelles to deal with. Does aspect ratio account for that much climb? What about acceleration? Does it work the same.

JoeBlogs,

My best find would be the Fw190 vrs F4U F6F and the P-51B vrs the F4U.

I got them from the author of "America's Hundred Thousand". He has the original copies and I scanned and posted them. You may see them on the web in various places now but I assure you they came from me first. I know because Frances Dean made notes in pencil on the reports. Every time I see them posted I see the notes on them so I know the copies came from me since Mr.Dean never published them. Hehe, my contribution to society.

Also the Docs I got from Vought have alot of good info I have never seen anywhere else on the F2G, F4U-3(a monster), F4U-4 and F4U-5. The F4U-3 was superior to the F2G in almost every way except sea level performance. It had a top speed of 490MPH at 27K.

I will do my web page soon I promise.

FYI, Barret Tillmans Corsair book has some very good annecdotal info but not much documentation. I would luv to speak to him an pic through his collection.

[wells]

DOA,

Calculate induced drag at 150 mph for both planes.

F4u with 314 sq ft of wing, aspect ratio = 5.35

Cl = 0.664
Cdi ~ 0.026
Induced drag ~ 470 lbs

P-38 with 327.5 sq ft and 8.25 aspect ratio

Cl = 0.929
Cdi ~ 0.033
Induced drag ~ 622 lbs

If the P-38 had the same aspect ratio as the F4u, induced drag would go up 54% to 959 lbs.  So, the P-38 gains 337 lbs of *excess thrust* by having a higher aspect ratio.  Since it weighs 17500 lbs, the climb rate benefits by 250 ft/min or so.

[joeblogs]

F4UDOA

The materials "Fw190 vrs F4U F6F, and the P-51B vrs the F4U," are those gov docs or articles in Flight Journal?

On CD, my aerodynamics are rusty but I thought that while you can nail two of the three drag parameters using dimensional information, the third can only be gotten from wind tunnel/flight tests (at least with the math available at the time, todays computers are getting us closer to full simulation of these effects).  

Also doesn't CD vary with angle of incidence, a function of the planes design and the angle of attack in the optimal climb attitude?

-Blogs

Originally posted by F4UDOA
Wells,

I thought Cd was constant? I know Cdi changes with speed but shouldn't the A/C with the lowest Cd climb better than one with higher drag such as the P-38? If the drag of the F4U is .04 at high AoA what is the P-38? They both have the same airfoil and the 38 has two engines nacelles to deal with. Does aspect ratio account for that much climb? What about acceleration? Does it work the same.

JoeBlogs,

My best find would be the Fw190 vrs F4U F6F and the P-51B vrs the F4U.

I got them from the author of "America's Hundred Thousand". He has the original copies and I scanned and posted them. You may see them on the web in various places now but I assure you they came from me first. I know because Frances Dean made notes in pencil on the reports. Every time I see them posted I see the notes on them so I know the copies came from me since Mr.Dean never published them. Hehe, my contribution to society.

Also the Docs I got from Vought have alot of good info I have never seen anywhere else on the F2G, F4U-3(a monster), F4U-4 and F4U-5. The F4U-3 was superior to the F2G in almost every way except sea level performance. It had a top speed of 490MPH at 27K.

I will do my web page soon I promise.

FYI, Barret Tillmans Corsair book has some very good annecdotal info but not much documentation. I would luv to speak to him an pic through his collection.

[HoHun]

Hi F4UDOA,

do you happen to have the climb rates for the F4U versions you posted the weight/power data for? I'd check if the data scales well - if it doesn't, probably a propeller change or something similar is to blame.

It's of course a simple "all else being equal" analysis, but that might be just what we need to confirm that all else wasn't equal ;-)

Regards,

Henning (HoHun)

[F4UDOA]

HoHun,

I absolutely do.

You can find them here.

F4U-1 and -1D performance and climb.

The -1 and -1D have differant prop designs. The latter being a paddle blade. In the F4U flight manual for the -1 it says to use the 6501A-0 design as it increases performance.

JoeBlogs,

Flight Journal did a lousy job with the report. I don't know were they got there copy. For the full report go here.



FW190 vrs F6F, F4U-1D

Notice the hand written scibble on the report. This was in pencil on the original copy I scanned.


BTW. I now AoA affects drag. But the F4U still has less total drag and better thrust to weight.

Wells,

The F4U still has less drag than the 38 and better thrust to weight. What Gives??  Also how about acceleration??

[joeblogs]

Uber links dude. - blogs

Originally posted by F4UDOA
HoHun,

I absolutely do.

You can find them here.

F4U-1 and -1D performance and climb.

The -1 and -1D have differant prop designs. The latter being a paddle blade. In the F4U flight manual for the -1 it says to use the 6501A-0 design as it increases performance.

JoeBlogs,

Flight Journal did a lousy job with the report. I don't know were they got there copy. For the full report go here.



FW190 vrs F6F, F4U-1D

Notice the hand written scibble on the report. This was in pencil on the original copy I scanned.


BTW. I now AoA affects drag. But the F4U still has less total drag and better thrust to weight.

Wells,

The F4U still has less drag than the 38 and better thrust to weight. What Gives??  Also how about acceleration??

[Urchin]

One minor (perhaps) thing I noticed.  I've no idea how to translate knots into MPH (that isnt my point though).  The (very nice) page you linked to has 3 climb speeds on there.

At 140 knots- the U.S. planes were better.  

At 160 knots- (i cant remember)

At 180 knots- The 190 was better.

What speed is auto-climb set to in Aces High?  I believe it is around 165-170 mph, so how many knots is that?  

This could play a large role in why the plane doesnt climb as well as you think it should... the A6M5s best climb speed was around 122 miles per hour at sea level.. in Aces High if you hit auto-climb, you start climbing at about 160-170 mph or so.  So the Zeke doesnt climb as well as it 'should'- because it is going to fast.

[HoHun]

Hi F4UDOA,

>The -1 and -1D have differant prop designs. The latter being a paddle blade. In the F4U flight manual for the -1 it says to use the 6501A-0 design as it increases performance.

Thanks! According to my estimate, the paddle blade brought an increase of about 7% in the propeller efficiency in the climb. A paddle-blade equipped F4U-1 would have climbed at 3170 fpm instead of the 2880 fpm at WEP. The F4U-1D still was better at 3370 fpm, but that was due to the increase in power from 2135 to 2250 HP.

On the other hand, the paddle blade apparently was not as good in high-speed flight - I'd say it cost the F4U about 7 mph top speed at sea level. (Drag differences between the F4U-1 and -1D may account for some of that, though.)

By the way, that F4U-4 is quite a monster - though no WEP power rating is given, the climb rates indicate that it used no less than 3000 HP :-)

Regards,

Henning (HoHun)

[Staga]

Urchin: Animal did post this link in another topic. There's a very nice converter for speeds, temperatures, areas etc...

http://www.joshmadison.com/software/convert/download.asp

[niklas]

It should be noted that 2250hp is only available at sealevel. In 2k or so, power dropped already down to 2000hp.
Looking at the propeller in the drawings iīd say every F4U in the comparison has a kind of paddle blade propeller. Or is the Hamilton 6443 equal to the Curtiss714?

F4UDOA, i always wanted you ask something: You published once a huge PDF document with many good aircraft data (climb, speed, drag, takeoff...). I only have hardcopies, but the scan qualitiy was poor so the prints are very hard to read.
I know that it must have been a lot of work to scan them, but is it *maybe* possible to scan them again in higher resolution, say 200dpi? Iīm not sure, but it is possible that it was scanned in Colourmode or greyscale? 200dpi and black&white scan mode (not greyscale!) should keep size small and it maybe becomes much better readable.

About the aircraft comparison test: I think it says a lot what the title says of the doc i was speaking about:
CVA airplanes (?)
F4U-1
F4U-4
F4U-3
RIVAL AIRPLANES   <<<<<  P51, P38, F6F(?)

So when the P51 and P38 are in official documents labeled rivals, then you shouldnīt be surprised about the result of the F4U-P51 comparison, nor the other aircraft comparison. I smell a huge interest from someone to have at least on the paper a clearly superior aircraft. I heard that the USAAF and Navy didnīt liked them very much?
The part "The fw190 and the corsair were ABOUT equal in rate of roll" tells you a lot. Itīs funny to read how those vague expressions are choosen in a situation of clear disadvantage, comparing REAL performances!
Oh yes, those comparison reports tell you a lot, and i donīt mean only flight performances

niklas

[F4UDOA]

Urchin,

I use a this web page for my metric as well as nautical mile conversions.

Conversion charts

140 Knots = 161MPH. The best climb speed for an F4U is 155MPH.

I haven't really experamented with sustained climb at different speeds. I tend to use zoom climb alot in AH. I build my speed to 300MPH and use a very low G pull and sustain a 4K a minute climb for some time. Flying the F4U in AH takes patience. I will test for best climb speed and post soon.

HoHun,

7% sounds about right. The late model F4U-1's would have climbed the best considering they were lighter and had less drag depending on condition(also they had the full 2250HP). The F4U-1D is the only A/C in AH that is modeled with external stores pylons regardless of loadout. Thes pylons took about 10MPH speed through out the speed range. In the "clean" condition the F4U-1D is as fast if not faster than the -1. The P-51,P-47 and F6F all carried similiar pylons but do not have them when not carrying bombs or DT's. And they are not penalized in speed when they drop there ordinance either.

Niklas,

I imagine you as an evil proffessor in a Labratory somewhere trying to build Frankenstein. Probably because your post are always so fiendish

Anyway I will will scan those docs in high res and post them.

They do say "Rival" on the charts but remeber it was a business to sell airplanes in this country. It was not a government run project. Based on that the test that were conducted such as the P-51B vrs F4U/F6F. A6M2/5 vrs F4U and others and FW190 vrs F4U and F6F were all conducted by the Government. NAVAIR specifically, and there interest was providing the best chance for the Naval Aviators to win not to sell Airplanes or propaganda.

Reasons this is true

1. All of the enemy A/C tested either performed exactly to performance specs or exceeded them. Ala the Ki-84 flying at 422MPH. I doubt any Japanese pilot ever flew a KI-84 that fast. The FW190 A5 flew exactly to spec. and the A6M2 flew according to the intelligance report many sorties with no operation failures even when the allied A/C such as the P-51A and P-40 were unable to because of mechanical problems.

2. The test performed by the Navy on the P-51B and later the P-51D were not just comparisons but suitabilty trials. It was to be designated the Seahorse had it had better low speed handling. They also tried the P-39 which would have been a tail dragger with a tail hook and designated the Aerobonita. The Airforce never tried to adopt the F6F or F4U for it's own use. However the one Army Air Corps pilot did score a kill in an borrowed F4U-1 on Gaudacanal in 1943. The Only AF victory in a Marine A/C of the war.

3. In the Vought archives docs you refer to the "Rival" A/C are also all performing up to spec if not better. Take a look at the P-47D stats. It's listed as being faster than anywhere I have ever seen listed by Republic. Also the test against the P-51B ,it was clearly superior over 25K and described as such.

So you see not everyone is as fiendish as you Niklas

[wells]

Wells,

The F4U still has less drag than the 38 and better thrust to weight. What Gives??  Also how about acceleration??

Power loading doesn't tell you squat about T/W if you don't know the prop efficiency at the climb speed.  I wouldn't call a 1% difference in power loadings 'better', equal is more like it.  Sure the F4u has less drag, but it's got less power too.  There's a couple of other things I thought of that might benefit the P-38.  It's got a lower power loading on the prop disc (power per unit area), which makes prop efficiency a tad better, it varies with speed.  It has a faster best climb speed (180 vs 155?).  There's an advantage there too, since climb rate depends on the speed that you climb at.

[HoHun]

Hi F4UDOA,

another thing to consider when comparing the P-38 and the F4U is that the P-38 uses a turbo-supercharger while the F4U benefits from exhaust thrust.

I have no idea whether the power rating for the F4U's R-2800 takes the exhaust thrust into account. I've seen exhaust thrust handled by adding a constant amount of horsepower for a specific (high) speed, so if it was done like that for the F4U, the F4U doesn't actually have the quoted power available in a low speed climb. (The ram effect is probably calculated for a fixed speed, too.)

The P-38 doesn't enjoy the advantage of exhaust thrust, but as the turbo-supercharger operates (mostly) independend of the aircraft's speed, it did have its rated power available at low speeds, too, which might be a difference to the F4U's rating.

Regards,

Henning (HoHun)