F8F Bearcat rate of climb

CORSNING said:

Agreed shortround. Kind of in the likeness of the Packard V-1650-3 vs V-1650-7 in the Mustang.

Jeff

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Or either of those vs the V-1650-9...

I know this is a bit off topic, but in regard to the climb record currently held by Rare Bear, I do believe there is a plane that can beat that record, or least come very close to beating it...and that plane is a Thunder Mustang...I've been doing quite a bit of research on the TM and its pilots claim it will peg the VSI gauge (which only goes up to 6K ft/per min), so they don't really know how fast it climbs (they know it's doing AT LEAST 6K ft/per min). They said 180 knots is optimal climb speed, and to keep the speed down to 180 in a climb takes about a 45 degree climb angle...that's impressive! Sorry for the off topic post, just thought it was interesting...

The Thunder Mustang is very impressive but it doesn't hold that initial rate for very long. It isn't all that fast relative to the Reno racers, but since it is a fiberglass unit. not built for wartime stress, it is relative light compared wuth the pwoer installed. What a neat plane!

Rare Bear is supercharged, runs ADI, and can run Nitrous Oxide if they want to do so ... and the Bear holds climb rate quite well, at LEAST to 10,000 feet or more. By the way, for those who don't know, Rare Bear set a world time to climb record for 3,000 meters (9,842.5 feet) in 91.9 seconds ... from a standing start. That was in 1972 when Rare Bear wan't making anywhere NEAR the horsepower it is now ... plus the plane has been sorted out quite nicely since 1972!

The Bear could beat it's own record significantly at this point in time, but there is no reason to spend the money to do so since it already owns the record and nobody else has gotten even close as yet ... at least nobody who has the ~$1M USD it takes to set the record.

GregP said:

The Thunder Mustang is very impressive but it doesn't hold that initial rate for very long.

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How do you know this? I've been doing quite a bit of research on the TM and I have not seen anything that that suggest this...

One clue is the 24,000ft service ceiling.

Another is getting 640hp from 601 cu in at 4800rpm. Anybody got any details on IF the engine has a supercharger?

Since the air at 10,000ft is 73.8% as dense as it is at sea level the engine will make 73.8% of the power unless the supercharger set up is rigged to accommodate the pressure/density drop.

Shortround6 said:

One clue is the 24,000ft service ceiling.

Another is getting 640hp from 601 cu in at 4800rpm. Anybody got any details on IF the engine has a supercharger?

Since the air at 10,000ft is 73.8% as dense as it is at sea level the engine will make 73.8% of the power unless the supercharger set up is rigged to accommodate the pressure/density drop.

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It doesn't come with a supercharger, but they have them available for the Falconer engine...

For comparison stock Bearcats had either a bit under 2100hp at sea level which increased to 2100hp at a bit over 3000ft and then tapered off to a bit over 1650hp at 10,000ft on the early ones (78.5% sea level power) without water injection, 115/145 fuel or shifting into high gear. The later ones (using 115/145) had 2200hp at take-off and still had 1975hp or so at 10,000ft.

I don't know what Rare Bear was using for power when it set the record but some R-3350 engines in Skyraiders ( source for Rare bears first engine?) were rated at 2700hp for take-off and 2700hp at 3700ft military power dry.

Without some form of supercharger the Falcon engine is going to be down almost 8% in power at 3700ft. (590hp?)

Rare Bear didn't have any guns, ammo, armor and had lighter fuel tanks than the military self sealing tanks and likely lighter radios/avionics. The Wright engine and new prop were heavier than stock though.

A Military Bearcat clean but fully loaded weighs just about 3 times what a Thunder Mustang does yet has 3.28 times the power at sea level and may have 3.48 times the power at 10,000ft (early one) to 4.15 times the power at 10,000ft for a late one.

With Rare Bear being both lighter and more powerful than a stock Bearcat a Thunder Mustang is going to need a LOT of power to take the record away.

When I looked at a Thunder Mustang with the Falconer V-12 it didn't have a supercharger. Hence my statement that it won't sustain the climb rate for too long. We all know what happens to normally aspirated engines as they go up in altitude ....

Yep, a Thunder Mustang would require a blower to be competitive in this event...I didn't take into consideration what altitude does to engine performance...

Shortround6 said:

For comparison stock Bearcats had either a bit under 2100hp at sea level which increased to 2100hp at a bit over 3000ft and then tapered off to a bit over 1650hp at 10,000ft on the early ones (78.5% sea level power) without water injection, 115/145 fuel or shifting into high gear. The later ones (using 115/145) had 2200hp at take-off and still had 1975hp or so at 10,000ft.

I don't know what Rare Bear was using for power when it set the record but some R-3350 engines in Skyraiders ( source for Rare bears first engine?) were rated at 2700hp for take-off and 2700hp at 3700ft military power dry.

Without some form of supercharger the Falcon engine is going to be down almost 8% in power at 3700ft. (590hp?)

Rare Bear didn't have any guns, ammo, armor and had lighter fuel tanks than the military self sealing tanks and likely lighter radios/avionics. The Wright engine and new prop were heavier than stock though.

A Military Bearcat clean but fully loaded weighs just about 3 times what a Thunder Mustang does yet has 3.28 times the power at sea level and may have 3.48 times the power at 10,000ft (early one) to 4.15 times the power at 10,000ft for a late one.

With Rare Bear being both lighter and more powerful than a stock Bearcat a Thunder Mustang is going to need a LOT of power to take the record away.

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I've done some research on Rare Bear in trying to find out how the 3350 was configured for the climb record (was it stock, was it modded, and if so, how much, etc.) So far I haven't been able to find out much about it...

grampi said:

Yep, a Thunder Mustang would require a blower to be competitive in this event...I didn't take into consideration what altitude does to engine performance...

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A very general rule of thumb is about 2% less power per 1000ft.

Shortround6 said:

One clue is the 24,000ft service ceiling.

Another is getting 640hp from 601 cu in at 4800rpm. Anybody got any details on IF the engine has a supercharger?

Since the air at 10,000ft is 73.8% as dense as it is at sea level the engine will make 73.8% of the power unless the supercharger set up is rigged to accommodate the pressure/density drop.

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A Falconer site says the engine is capable of 1600 hp with turbo or supercharger. Would nitromethane provide the hp? I have read it will provide 2.3 times the power of equivalent quantity of gasoline.

When they actually extract 1,600 HP from the Falconer, it doesn't tend to last long. It was never designed for that power level.

The parts LOOK beefy until you see them next to Allison rods in a racing Merlin alongside the other Merlin parts. Then they look positive spindley and tiny.

The engine may be capable of that for short term ground use.

We are now getting into a very grey area of use for aircraft.

FlyboyJ or Greg or some others on this forum may have a much better Idea of what is allowable for general aviation use and what is allowed for racing use in aircraft engines.

Also remember that what an engine may tolerate for a 6-12 second drag race or even a tractor pull may NOT be what it can tolerate for 90-120 seconds in a hard climb in an airplane.

Most of the FAST racing aircraft are in the Experimental or Experimental Exhibition category and can pretty much do what they want. Most of the top warbird teams have a race engine or two and a "cruise around" engine or two. They install the cruise around engine to get to Reno and get home from Reno. The race engines are in the plane for one or two weeks a year. It is hoped that they will be going so fast when they finish the race or break that the pilot, should the outcome be "break," will be able to swap airspeed for altitude and get the beast on the runway. Mostly, they DO.

Sometimes not, and sometimes with very bad results.

No Top Fuel drag race engine will survive more than about 5 - 7 seconds of operation (the spark plugs are basically gone and the engine diesels for the last few hundred feet of a normal run, which is 1,000 feet these days, so they are completely useless for aircraft operation. Any Merlin at Reno will put out 1,500 ± HP for much longer than the 5 minutes Rolls Royce claimed. It will likely put out out 1,500+ HP for over two hours, maybe as many as 100 hours. At 3,850 HP it will be fine for 2 - 3 laps and then will be heat-soaked, and will have to either be throttled back or die. Many have done just that. So have other engines that are pressed WAY beyond design limits. The R-3350 is VERY tolerant of high manifold pressure but is also very INTOLERANT of any rpm that reaches 3,000 or over. If you hit 3,000 rpm, you will be flying scrap metal going downward shortly after reaching that rpm.

The R-3350 in Rare Bear can put out 4,000 HP on normal, regular air and probably 4,250 - 4,400 HP on Nitrous Oxide. It will cruise around at 3,500 - 3,600 HP for probably DAYS or weeks. It will survive 4,200 HP for probably 15 laps if they had the Nitrous capacity to do it, but they only carry enough for 2 - 3 laps ... that is IF they use it. Since Rod Lewis bought the plane, they have not used Nitrous in a Reno Gold Final race. Lyle Shelton almost alwyas DID use it, but never admitted it. You could tell because the NOS truck would pull up when the Bear got back to the pits and the exhaust turned dirty brown on the last two laps as he picked up speed ... a sure sign of Nitrous Oxide.

see next post

Yes, but could a Falconer engine pull 1000 hp for a reasonable amount of time for a climb record attempt and, since nitromethane does not need much air, maintain that 1000 hp to 10k? If so, maybe the Thunder Mustang could beat the record, or, maybe another special designed aircraft.

Also, how about a NASCAR engine? They generate over 850 hp on 110 octane gas for several hours at a high load level. Add some nitrous to get some more power and maintain a good level of hp up to 10k and you might have a power plant to break a record.

From Wiki: Nitromethane - Wikipedia, the free encyclopedia

"The amount of air required to burn 1 kg (2.2 lb) of gasoline is 14.7 kg (32 lb), but only 1.7 kg (3.7 lb) of air is required for 1 kg of nitromethane. Since an engine's cylinder can only contain a limited amount of air on each stroke, 8.7 times more nitromethane than gasoline can be burned in one stroke. Nitromethane, however, has a lower specific energy: Gasoline provides about 42–44 MJ/kg whereas nitromethane provides only 11.3 MJ/kg. This analysis indicates that nitromethane generates about 2.3 times the power of gasoline when combined with a given amount of oxygen."

It also means you need about 4 times (or just under) the weight of nitromethane for the same power as gasoline. Switching fuels in flight is not practical without a complete secondary fuel system. For a 5-10 minute record run it might be possible, it is going to ake longer to descend and land that than the climb up.

" Exhaust gas from an internal combustion engine whose fuel includes nitromethane will contain nitric acid vapour, which is corrosive, and when inhaled causes a muscular reaction making it impossible to breathe. People exposed to it should wear a gas mask."

Which is not really a problem for the pilot as he may be on oxygen anyway. It may be a problem for the aircraft unless quick washdowns/decontamination are done on landing.

"Nitromethane was not known to be a high explosive until a railroad tanker car loaded with it exploded on June 1, 1958.[6] After much testing it was realized that nitromethane was a more energetic high explosive than TNT, although TNT has a higher velocity of detonation and brisance. Both of these explosives are oxygen poor and some benefits are gained from mixing with an oxidizer, such as ammonium nitrate. Pure nitromethane is an insensitive explosive with a VoD of approximately 6,400 m/s (21,000 ft/s), but even so inhibitors may be used to reduce the hazards. The tank car explosion was speculated to be due to adiabatic compression, a hazard common to all liquid explosives. This is when small entrained air bubbles compress and superheat with rapid rises in pressure. It was thought that an operator rapidly snapped shut a valve creating a "hammer-lock" pressure surge."

may or may not be a problem.

and

"Nitromethane is usually used with rich air/fuel mixtures because it provides power even in the absence of atmospheric oxygen. When rich air/fuel mixtures are used, hydrogen and carbon monoxide are two of the combustion products. These gases often ignite, sometimes spectacularly, as the normally very rich mixtures of the still burning fuel exits the exhaust ports. Very rich mixtures are necessary to reduce the temperature of combustion chamber hot parts in order to control pre-ignition and subsequent detonation. Operational details depend on the particular mixture and engine characteristics."

A reason for the long zoomie headers on fuel dragsters. Get the flames away from the car body. Drag of 2-3ft long header pipes on an aircraft???

Regular Methanol is a much better fuel for record setting aircraft. It is a lot less twitchy. It allows for more power than gasoline because you can burn twice as much per pound of air and it has a lower flame temperature than gasoline which helps with the cooling load.

The nascar engine may need a supercharger as the engine will loose almost 20% in power by the time it reaches 10,000ft.

The difference between drag cars ( or even nascar racers) is that the driver can walk back to the pits after an engine failure.



Out of 20-30 Nascar engines starting a race how many drop out due to engine failure every race? even if it's only 2-3 per race?

Pilot interview for 0-3000meter climb record flight:
Team manger to pilot "well, Jim Bob (pilot) we reckon we got a good chance of setting the record, we got the power and we figure that there is only about 10-20% chance of the engine grenading on any given record attempt flight. Pay is $1000.00 a week, $500.00 a record attempt flight with a bonus for setting the record and we provide the parachute and repacking of the parachute at no cost to you. Whatdo you say? take the job?"



However.

Shortround6 said:

It also means you need about 4 times (or just under) the weight of nitromethane for the same power as gasoline. Switching fuels in flight is not practical without a complete secondary fuel system. For a 5-10 minute record run it might be possible, it is going to ake longer to descend and land that than the climb up.

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I'm not sure this would be a big issue for a record run.

" Exhaust gas from an internal combustion engine whose fuel includes nitromethane will contain nitric acid vapour, which is corrosive, and when inhaled causes a muscular reaction making it impossible to breathe. People exposed to it should wear a gas mask."

Which is not really a problem for the pilot as he may be on oxygen anyway. It may be a problem for the aircraft unless quick washdowns/decontamination are done on landing.

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But, this is done regularly during drag races so the technology and physiology is well known.

"Nitromethane is usually used with rich air/fuel mixtures because it provides power even in the absence of atmospheric oxygen. When rich air/fuel mixtures are used, hydrogen and carbon monoxide are two of the combustion products. These gases often ignite, sometimes spectacularly, as the normally very rich mixtures of the still burning fuel exits the exhaust ports. Very rich mixtures are necessary to reduce the temperature of combustion chamber hot parts in order to control pre-ignition and subsequent detonation. Operational details depend on the particular mixture and engine characteristics."

A reason for the long zoomie headers on fuel dragsters. Get the flames away from the car body. Drag of 2-3ft long header pipes on an aircraft???

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I think there are several mitigating issues here. First, the exhausts are designed to provide down force for the dragster, which would require over a 90 degree turn with correct radius. I am sure this is part of the reason for the length. I would suspect that this length would be less for a turn to provide thrust rather than down force. Also, the exhaust energy for a 1000 hp nitromethane engine would be much less than a 8,000-10,000 hp dragster engine so I suspect exhaust length would be significantly reduced. Finally, best climb speed for, say, the Thunder Mustang, is less than 200 mph, which, while still important, drag is considerably less of an impact than on top speed, for instance.

Regular Methanol is a much better fuel for record setting aircraft. It is a lot less twitchy. It allows for more power than gasoline because you can burn twice as much per pound of air and it has a lower flame temperature than gasoline which helps with the cooling load.

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I am certainly not an engine specialist, as I consider you to be. I have for the most part been throwing mud against the wall, so if I was to build a plane to attempt to beat the 10k time to climb record, I certainly would cede expertise to your opinion over mine any day.

The nascar engine may need a supercharger as the engine will loose almost 20% in power by the time it reaches 10,000ft.

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Maybe. However, if it was using nitromethane, and the engine was limited to 1000 hp, (for no more than three minutes) it may be possible to maintain the 1000 hp up to 10k by simply throttling up. This maybe also be true with methanol (with nitrous?). This may be effective for the Falconer and the NASCAR engines. I don't know about the Falconer but the NASCAR engines are run at full power for nearly three hours with power cycling. I think these are really tough engines and uprating them to 1000 hp for three minutes does not seem unreasonable. In addition, there should be plenty laying around to mod for a plane.

Pilot interview for 0-3000meter climb record flight:
Team manger to pilot "well, Jim Bob (pilot) we reckon we got a good chance of setting the record, we got the power and we figure that there is only about 10-20% chance of the engine grenading on any given record attempt flight. Pay is $1000.00 a week, $500.00 a record attempt flight with a bonus for setting the record and we provide the parachute and repacking of the parachute at no cost to you. Whatdo you say? take the job?"

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I don't know, I think historically, there have been many pilots, climbers, drivers, etc., climb into a vehicle to attempt to set a record, achieve an accomplishment, win a race, or go into space, in an event far more dangerous than this would be.

I think the Falconer engine could be set up for a world climb record attempt, but these Thunder Mustangs are all privately owned units and anyone who spends the hours required to build one wants to keep flying it. So, I think the trick would be to offer up two Falconer record attempt engines and assure the owner that he would have a functioning engine when the fun was over, not to mention a functioning propeller.

Some owners might well want to take the change if they were using someone else's engine and prop for the attempt and if the costs were covered.

The trick would be to come up with the ~$750,000 USD for the record attempt plus the money for the race engines and prop, plus costs for the record attempt for the crew and owner.

If there is anyone out there who wants to attempy it and has a spare $2M USD, let us know and we can find a Thunder Mustang ownewre willing to give it a try.