Difference in rudder size on Corsair a d Bearcat

I was down at the local airport yesterday looking at a Corsair and Bearcat parked side by side and I noticed the HUGE difference between the size of their rudders. I was surprised the Bearcat rudder was so small

First, not that it makes any difference in the rudder size but that is a Goodyear F2G Super Corsair. That model had a P&W R-4360 rather than the P&W R-2800 found in the F4U, and also had a bubble canopy rather than the original "razorback" configuration.
Second, that particular Bearcat is an F8F-1 which was part of the original production run. In 1948 Grumman introduced the F8F-2, an improved version of the aircraft. Among the modifications was an increase in the height of the rudder to increase lateral stability.

I knew the Corsair was an F2G with the big engine, I didn't know what model the Bearcat was

If you take the rudder area multiplied by the arm, I'd bet the result is almost identical ... but, I also don't have the areas and the distance from spinner to rudder hinge line at this time. Sort of a poor man's tail volume calculation.

Here is a short tail volume calculation:

https://freeflight.org/Library/TechLibrary/TailVolumeCalculation.pdf

It is for models, but also works for full-size aircraft. Actually, the full-size calculations are decently complex, especially if you are trying to "fix" some handling characteristic.

Having studied rudders and tail plane structures in depth, I can confirm that it is fffing complicated, I dont know if that helps.

pinsog said:

I was down at the local airport yesterday looking at a Corsair and Bearcat parked side by side and I noticed the HUGE difference between the size of their rudders. I was surprised the Bearcat rudder was so small

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My somewhat educated opinion and guess:
The large rudder on the Corsair indicates concern for getting a lot of rudder authority at low speed.

The Bearcat was a refined and evolved late war product. I believe the engine was angled down and to one side. This counteracted both torque reaction and p-factor. So I suspect the Bearcat didn't need as much of a rudder or fin.

Koopernic said:

My somewhat educated opinion and guess:
The large rudder on the Corsair indicates concern for getting a lot of rudder authority at low speed.

The Bearcat was a refined and evolved late war product. I believe the engine was angled down and to one side. This counteracted both torque reaction and p-factor. So I suspect the Bearcat didn't need as much of a rudder or fin.

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Now that you've said that, I remember reading that as well (the engine angles down and to one side) and it would definitely explain the difference in rudder sizes.

On most WWII-era fighters, the engine mount is canted downward, has left or right thrust, the wing has positive incidence, the stab has negative incidence, and the fin and rudder have right or left built in.

On the Super Corsair, the rudder is split. The top portion is rudder and the bottom rudder is connected to the throttle and perhaps airspeed. It definitely and applies right rudder when you increase throttle, but that might trim out a bit at speed, I'm not too sure about the airspeed portion of it, but it definitely comes in at approach speed with throttle.

GregP said:

On most WWII-era fighters, the engine mount is canted downward, has left or right thrust, the wing ahs positive incidence, the stab has negative incidence, and the fin and rudder have right of left built in.

On the Super Corsair, the rudder is split. The top portion is rudder and the bottom rudder is connected to the throttle and perhaps airspeed. It definitely and applies right rudder when you increase throttle, but that might trim out a bit at speed, I'm not too sure about the airspeed portion of it, but it definitely comes in at approach speed with throttle.

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The split rudder in the F2G actually has a good story, it was designed by the test pilot (Don Armstrong) to solve the torque issues at low speeds due to the enormous power available for take off (3000hp). And it seems that it well solved the problem because in later interviews it was said by the same test pilots that the take offs are smooth even at full power.

''Additional data by Don states that the aircraft had a problem with the new R-4360-4 engine. For example, the aircraft tended to veer to the left when given full power on takeoff, requiring almost full right rudder to maintain a straight course. Don envisioned setting both the vertical fin and rudder on a "pedestal". Don made a couple of preliminary drawings and took them to Dr Arnstein (a highly respected engineer & designer), who in turn had his people design and make the necessary linkage equipment and install it in the F2G. ''

This auxiliary rudder is well covered in the pilot's handbook and it works when flaps are deployed at 30 degrees or more:

Btw Greg, the F2G has a highly interesting history since the only flight data that we have is from 1944 and without water injection, but numerous reports say that P&W gave it water injection in 1945 and that was tested in Patuxent until 1948. Don't doubt in contact me if you are interested I would be more than happy to help

Thanks for that, Metrallaroja. My understanding of the split rudder came from a conversation with a demo display pilot once, Bob Odegaard, who told me the split rudder came in at low speeds to help with torque. He mentioned low speeds and throttle, but never said it was connected to the flaps.

Perhaps he thought at the time that the real answer was likely too technical of an explanation for an airshow question. I am sure he knew the real setup since he was flying it and had a second one in restoration at the time. The guys who fly these things tend to KNOW the system very well.

PM sent to you, and thanks!

GregP said:

Thanks for that, Metrallaroja. My understanding of the split rudder came from a conversation with a demo display pilot once, Bob Odegaard, who told me the split rudder came in at low speeds to help with torque. He mentioned low speeds and throttle, but never said it was connected to the flaps.

Perhaps he thought at the time that the real answer was likely too technical of an explanation for an airshow question. I am sure he knew the real setup since he was flying it and had a second one in restoration at the time. The guys who fly these things tend to KNOW the system very well.

PM sent to you, and thanks!

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That is great, Bob was a legend! R.I.P.
Maybe they changed the setup when they restored the plane, it was in a very bad shape.

Btw a short video about Bob and Race 57, maybe interesting for people that doesn't know about him: