Hello everyone,

as I was checking some 3-view drawings for a P-47 that I'm building, I noticed that the fin and rudder seem to be angled very slightly to induce a right yaw. That is the fin and rudder assembly is mounted with a slight angle with respect to the fuselage centerline, with the front end of the fin slightly offset to the port side.
I double checked with other P-47 3-views and not all of them show this feature. I assume that it's a problem with the 3-views, not that some versions of the airplane had this feature and other did not. I also noticed the same angled fin and rudder in a 3-view drawing of a Re-2005. And I can only assume that other planes had this feature as well.

So I have 2 questions:

• Can anyone confirm whether the P-47 did in fact use an angled fin and rudder?
• Would it be wise to replicate this feature in a scale model as far as takeoff/flight/landing behavior is concerned? And if this angled fin is implemented, what about NOT using right thrust?

I ask this last bit because space for the engine is going to very limited, so I cannot angle the engine to have right thrust and then offset its mounting location to have the prop at the center of the cowl. I'd have to angle the engine and then live with an off-center prop hub. Mounting the engine exactly straight on would solve the problem.

Andrea.

I know that the full size Corsair has the vert stab off set. There was talk of this on some other thread some time back. I think this is one of those scaling questions when you get down to size of air molecules and airspeed, p factor and such. Why take the chance? It is something that even most serious scale guys and judges wont notice and if it is that noticeable....it is probably way to much. If you should decide to do it, you can always trim it out with the trim tab (scale) or with rudder trim which we currently do. So whatever you decide to do, keep us in the loop

I tried to do a quick search before opening this thread, but I couldn't find anything. Probably I used the wrong keywords. I found some threads about down and right thrust with some members saying that they don't use right thrust and use the rudder trim instead. Sometimes mixing the rudder and the throttle channel.

At this stage I think I'll try to replicate this offset and see how it goes. As you say, in the worst case I should still be able to trim it out. And right rudder will be needed anyway for takeoff.

I'm not completely sure what I'll do with this plane. This is my first warbird and I just started construction. I set as a goal to try and make it as scale as I can, mostly to see what's my limit. It's not intended for competition, though that's not out of the question if the result turns out to be good.
Not having access to a fullsize P-47 to take photos and measurements is a great limitation, but at least I'll be ready should I decide in the future to model a plane that there are no existing survivors of.

Andrea.

Andrea, in scale, the sky is the limit. You are never done detailing, you just stop....... Good luck and keep us in the loop

Hehe, I know
My previous sentence "I set as a goal to try and make it as scale as I can, mostly to see what's my limit" should have read "I set as a goal to try and make it as scale as I can, mostly to see what's my limit before I get bored".

Andrea.

I built the Brian Taylor Kingfisher. The Kingfisher was also a Chance-Vought built aircraft like the Corsair. In the Brian Taylor plans it showed the off set fin. I also questioned this during my build and I believe Chad Viech commented about the original being off set and that Brian Taylor drew his plans to scale. I built mine without the off set but did use some right thrust on the model. Some mention was made to the effect of the off set fin and engine speed. Rudder trim might have to change to correspond to the speed of the aircraft when using the off-set where the trim would basically stay the same when using the right thrust. Not sure if this is the case, just that the possibilities were discussed.

here's some info:

Appreciate your comments Hi Tech, but: #1- a rudder is on a aircraft to control "Yaw" about the vertical axis! #2- The rudder is on the aircraft to overcome the adverse "yaw" created by the down aileron in a turn. Next time you are in a real aircraft, start a left or right turn, with out touching the rudder and you will notice the nose of the aircraft moves in the opposite direction that you want to turn, before lift of the wing overcomes it and it starts turning in the direction you want the aircraft to go in. The vertical stabilizer is designed by the aircraft designers to "hold" the aircraft in a straight line when flying at the design Cruise speed. Example, the P-51B and D models, if you are standing behind the aircraft looking forward, the leading edge of the vertical stab is offset to the left, 1.26 degrees. The reason for this is to overcome torque and "P" factor in straight and level flight,at the design cruise speed. If you exceed the design Cruise speed, which if I recall correctly is 289MPH, IAS, it will turn to the right without any input from the pilot. If you slow to less than 289MPH, IAS, it will turn to the left without any input from the pilot. But, that is why we have trim-tabs, so that you may trim the aircraft to fly "hands off" at any speed, and to relieve control pressure! The only thing the fuselage does for an aircraft is carry the pilot, sometimes fuel, the engine and etc. The Fuselage does nothing to aid flight, as it only produces DRAG! Check the shape of many supersonic aircraft and see how they gradually get to the famous "coke" bottle shape. By the way, these are not my flight princpals, these were established more than 70 or 80 years ago by people who were a lot smarter than I am. I Was a professonal pilot from 1953 to 1996, with 22,924 hours total time, and I am still learning today!!!!«

Are you talking to me? Hitech? (I'm Chistech) Not sure what the "but" is for. Basically what you said, I already said in fewer words. With the offset fin, you need to trim for different speeds. I also said "rudder" trim vs trim tabs as most models don't have operational trim tabs like full scale so we need to trim the whole rudder with our models.

Just an update for anyone that may stumble on this thread in the future,

since I opened this discussion I came across a great source of original factory drawings for several aircrafts, including the P-47 (http://aircorpslibrary.com).
In particular the "empennage installation" drawings (89E51000) for the P-47 clearly show that the fin and rudder were NOT mounted at an angle. They were dead straight. By the way, the stab was set at 2.5° positive incidence.
So it seems like 3-views showing an offset fin on a P-47 are wrong on this point.

Andrea.