What is the climb rate of an F2G Corsair?

[GregP]

Hi Elvis,

MTOW is Maximum Takeoff Weight and has nothing whatsoever to do with engine power.

Most British flight reports I have seen were corrected to 95% takeoff weight because you can't take off and get to altitude for a test without burning some fuel. I have yet to see one corrected to 95% power setting, but I have an open mind there as I have not read all the British flight test reports.

The British Merlin flight test reports I have read mention M.S. Gear (Medium Supercharger) and F.S. Gear (Full Supercharger). These are just the two gear ratios available in a 2-speed supercharger. You take off and use M.S. gear until you reached about full throttle height (FTH), throttle back and shift to F.S. gear, and then climb until service ceiling. That's why the top speed graph has the two dogtooth areas of top speed. The max for both is full throttle height for the supercharger gear you are in at the time. When you get there, the speed starts to fall off until it becomes time to slow down and shift into the next gear. The speed increases with power until FTH again. Some engines allowed takeoff without supercharger engaged, and you then went to M.S. at some intermediate height and F.S. at the M.S. FTH height plus a bit.

METO is an American term meaning power is at "Maximum Except TakeOff." Not all engines had an METO power setting. It was usually set by cylinder head temperature on the test stand, and was then transferred to the pilot manuals as a chart.

Military power is maximum power at rated rpm without ADI. Sometimes WEP allowed elevated rpm above rated rpm. WEP Dry was max power at elevated rpm without ADI. WEP Wet was max power at elevated rpm with ADI.

The British radial used in the Sea Fury was a Bristol Centaurus. It made max power in M.S. gear (2,560 HP at 9.5 lbs boost and 2,700 rpm). In F.S. gear, max power was 2,300 HP at a higher altitude. The Centaurus had sleeve valves and could NOT handle extra rpm. The monkey-motion valve gear would fail if you got to 2,800 rpm. Ask any Centaurus owner. If you stayed within limits, it was almost bullet proof and made enough power for the aircraft to be quite sprightly. It was not very "hot-roddable" as it was at or near the limits of the design power in the Sea Fury. That is NOT a knock on the Centaurus. It was a solid, reliable radial and still is. It's just not going to win Reno, and that has nothing whatsoever to do with WW2 anyway.

The Wright R-3350 has it all over the Centaurus in ability to be hot-rodded for racing, but the Wright also blows up on a regular basis, so it lets you know that it doesn't LIKE to be hot-rodded. We're very close to the end of the R-3350 engines as they are out of available main bearings. Of course, if you HAVE some good mains, you're lucky and in like Flint. They are still overhaulable as long as you don't need mains. The Centaurus can't be hot-rodded but is solid and reliable, If I had a Sea Fury, I'd want a Centaurus, myself. I'll take solid, reliable power every time over the absolute max HP that might live and might not, and my wallet would thank me. I only know one guy who can hone Centaurus cylinders and make them round again, but they are technically still overhaulable, too. Ellsworth Getchell recently went through his and his Sea Fury is back flying. See below:

http://www.gkbgraphics.com/wp-content/uploads/2013/05/Sea-Fury.jpg

Regards, Greg

 

[wuzak]

I've never seen a flight test report at 95% rated power, myself. Every report I've seen is at Military, WER dry, or WER wet power. The British usually report pounds of boost gauge and the U.S.A. uses inches of Mercury absolute.

But some may be reported at a lower power. The ones I have seen were listed as cruise-climb.

Would be interested to read the ones you are referencing above. Maybe I've seen it and just have not noticed the 95% correction part. Can't say.

Greg,

MTOW, not rated power.


Elvis

Hi Elvis,

MTOW is Maximum Takeoff Weight and has nothing whatsoever to do with engine power.

Greg, Elvis never said that MTOW had anything to do with power.

You seem confused.

The British performance tests seem to have used 95% of MTOW as the testing weight, and used correction factors to bring the performance back to what it would be at that weight.

 

[Shortround6]

test procedures changed with time in most countries.

In this test;
Tempest V Performance Test

the climb performance was measured at "normal" take-off weight 11,480lbs while the speed test was done at 95% of take-off (NOT MTOW) weight. 10,900lbs.
MTOW would include bombs or drop tanks.

Other tests may specify the test weight. If a weight is NOT given then normal gross weight clean is a good assumption.
But then you have to know the aircraft as the early P-40s with 3 internal tanks only counted two of them at normal gross. The 3rd tank was overload even though it was internal.

A test of the Spitfire MK VIII was done (or corrected to) the max clean take-off weight of 7,770lbs in one part of the text yet the charts are labeled 7,690lbs which is about 99%

 

[wuzak]

Thanks for the correction SR.

 

[GregP]

I'm not confused at all. Yes, I may have misinterpreted Elvis' post, for sure ... but there's nothing incorrect with mine. Only the fact that perhaps I interpreted his post to mean he was thinking they were testing at 95% power. We don't all word things the same and we don't all understand things that were said as the same things the speaker thinks he/she said. So, mea culpa.

Maybe that's why people say that only 30% of all communication gets across as intended, and only some 10% gets retained. Wouldn't be the FIRST mistake I ever made in here, would it?

Made me think, and that can't be bad.

Anyway, cheers to you and Elvis!

 

[grampi]

Hi Elvis,

MTOW is Maximum Takeoff Weight and has nothing whatsoever to do with engine power.

Most British flight reports I have seen were corrected to 95% takeoff weight because you can't take off and get to altitude for a test without burning some fuel. I have yet to see one corrected to 95% power setting, but I have an open mind there as I have not read all the British flight test reports.

The British Merlin flight test reports I have read mention M.S. Gear (Medium Supercharger) and F.S. Gear (Full Supercharger). These are just the two gear ratios available in a 2-speed supercharger. You take off and use M.S. gear until you reached about full throttle height (FTH), throttle back and shift to F.S. gear, and then climb until service ceiling. That's why the top speed graph has the two dogtooth areas of top speed. The max for both is full throttle height for the supercharger gear you are in at the time. When you get there, the speed starts to fall off until it becomes time to slow down and shift into the next gear. The speed increases with power until FTH again. Some engines allowed takeoff without supercharger engaged, and you then went to M.S. at some intermediate height and F.S. at the M.S. FTH height plus a bit.

METO is an American term meaning power is at "Maximum Except TakeOff." Not all engines had an METO power setting. It was usually set by cylinder head temperature on the test stand, and was then transferred to the pilot manuals as a chart.

Military power is maximum power at rated rpm without ADI. Sometimes WEP allowed elevated rpm above rated rpm. WEP Dry was max power at elevated rpm without ADI. WEP Wet was max power at elevated rpm with ADI.

The British radial used in the Sea Fury was a Bristol Centaurus. It made max power in M.S. gear (2,560 HP at 9.5 lbs boost and 2,700 rpm). In F.S. gear, max power was 2,300 HP at a higher altitude. The Centaurus had sleeve valves and could NOT handle extra rpm. The monkey-motion valve gear would fail if you got to 2,800 rpm. Ask any Centaurus owner. If you stayed within limits, it was almost bullet proof and made enough power for the aircraft to be quite sprightly. It was not very "hot-roddable" as it was at or near the limits of the design power in the Sea Fury. That is NOT a knock on the Centaurus. It was a solid, reliable radial and still is. It's just not going to win Reno, and that has nothing whatsoever to do with WW2 anyway.

The Wright R-3350 has it all over the Centaurus in ability to be hot-rodded for racing, but the Wright also blows up on a regular basis, so it lets you know that it doesn't LIKE to be hot-rodded. We're very close to the end of the R-3350 engines as they are out of available main bearings. Of course, if you HAVE some good mains, you're lucky and in like Flint. They are still overhaulable as long as you don't need mains. The Centaurus can't be hot-rodded but is solid and reliable, If I had a Sea Fury, I'd want a Centaurus, myself. I'll take solid, reliable power every time over the absolute max HP that might live and might not, and my wallet would thank me. I only know one guy who can hone Centaurus cylinders and make them round again, but they are technically still overhaulable, too. Ellsworth Getchell recently went through his and his Sea Fury is back flying. See below:

http://www.gkbgraphics.com/wp-content/uploads/2013/05/Sea-Fury.jpg

Regards, Greg

I see statements like this quite often saying that certain warbird parts are no longer available. I guess I don't understand why main bearings can't be made...they're just pieces of steel made to a particular size and shape...it is after all 2017 and I think the technology exists to make engine bearings...

 

[GregP]

You could easily make R-3350 mains, but you'd never recoup the investment. The cost to PMA them would eliminate all the profit.

They consist of three large roller bearings; front, center, and rear. Not sure we know the heat treat levels, but maybe. So, if you wanted to PAY for the equipment and make some, you could do it, but you'd be making for yourself only. If you made some and sold them, and when one of them failed, the money you'd lose in the lawsuit would wipe out almost anyone!

But, hey, if you want to make some, go for it! The rod bearings are silver-lead-indium pressed bearings. I momentarily forgot and posted steel-silver-lead before. Forgot the indium.

And good luck to you! The market is small and ALL the players are wealthy enough to go for you if your product is inferior and fails in their prize mount, chewing up parts worth a LOT more money than your bearings will ever bring you!

Remember, P&W had experts on bearings and went through a LOT of iterations before getting them right!

They're about out of P-51 prop blades, too. But you can buy new ones from the Czech Republic. Try suing THEM in U.S. courts! They'll just laugh at you! You can also get a couple of Grumman Albatross props and take 2 blades from each one and have them reground to P-51 blade number shape and diameter. That works, until they run out of Albatross props.

That's probably one reason why so many P-51s are Experimental ... the props likely don't meet the diameter requirements for the Limited category. The museum flies three P-51s. 1 is Experimental, 1 is Experimental Exhibition, and 1 is Limted. There HAS to be a reason for it, right? I think I know ONE other guy who flies one Limited. The rest I know are Experimental, EE, or Restricted. It would be interesting to know how many are currently registered and in what category, but I'm not curious enough to spend time on it.

Unless I remember wrong, the Limited Type Certificate Data Sheet No. 11 requires an 11' 2" diameter for P-51C and D and 11' 0" diameter for P-51K, with a very limited set of prop blade part numbers. I've never seen the prop requirements for a P-515B. After the props get chewed up by the occasional gravel rock for 70 years, they typically don't meet the diameter requirement. They then get sold as racing props that will be cut down anyway and run on Experimental Exhibition category planes. I doubt you can safely run an 11" 2" diameter prop on a racing-configured V-1650 P-51 at 3,600 rpm (depending on reduction ratio) without shedding a blade or exceeding Mach 1 at the tip anyway. I don't think there IS a Limited Category for the P-51A variant. I think there are two of them and we operate one and it isn't Limited category. It has Curtiss Electric prop, 50-spline. Could be wrong there, but Data Sheet No. 11 doesn't mention any other P-51 variants ... just B, C, D, and K, with all serial numbers accounted for.

 

[DarrenW]

I know that this thread is more than a few months old but I will resurrect it anyway.

I have a question concerning British flight tests. There was a discussion in this thread about the 95% of TO weight described in some test reports. Is it because of the fuel burned during testing?

Case in point, a Corsair tested by the British (with an actual take-off weight of 12,080lbs) was given a "corrected" weight of 11,500lbs:

http://www.wwiiaircraftperformance.org/f4u/kd227.pdf

 

[GregP]

When they got their data, they had burned that much fuel, and they corrected to the actual weight as calculated by the fuel burn.

 

[DarrenW]

When they got their data, they had burned that much fuel, and they corrected to the actual weight as calculated by the fuel burn.

Thanks Greg for the clarification.