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Design => Stunt design => Topic started by: dennis lipsett on August 05, 2012, 08:23:51 PM
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I'm just curious about something that I might need to redo. In production twins the rudder and fin is usually larger then a single engine model and I believe that the stab and elevator has increased area. If doing a twin engine variant of a single engine model do the surfaces have to be enlarged and what would be a reasonable percentage.
Thanks in advance for any info.
Dennis
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I'm just curious about something that I might need to redo. In production twins the rudder and fin is usually larger then a single engine model and I believe that the stab and elevator has increased area. If doing a twin engine variant of a single engine model do the surfaces have to be enlarged and what would be a reasonable percentage.
Thanks in advance for any info.
Dennis
In a full size twin engine aircraft, the vertical tail must be large enough to provide sufficient lateral stability and control for single engine operation, meaning the vertical tail must be able to handle the assymmetric thrust when one engine is out. For our control line stunt models, vertical side area is good to a point but it is not necessary to be increased just because there is a second engine, assuming that both engines will be running during the flight pattern.
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Thank you for the information. I was hoping that I didn't have to redo the back end.
Dennis
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Thank you for the information. I was hoping that I didn't have to redo the back end.Dennis
Dennis,
It may be fashionable, for appearance sake only, to increase the span of the "back end."
The extra sq's could make a difference in performance?
That could be hashed over.
You didn't mention the model?
Charles
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(Clip)
The extra sq's could make a difference in performance?
(Clip)
Charles
Why? And in what way? What "difference in performance" are you looking for? Yes, it looks like you are just wondering about the question, but why suggest it if you have no real technical reason for doing so?
Keith
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In a full size twin engine aircraft, the vertical tail must be large enought to provide sufficient lateral stability and control for single engine operation, meaning the vertical tail must be able to handle the assymmetric thrust when one engine is out.
I never knew that!
Good reply mate.
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I did know that, but didn't consider it all that important for CL, and made the mistake of designing a twin-fuselage thing (for a couple of Norvel 061s) that had smallish, low aspect-ratio tail fins. It flew great, up until the point where the inboard engine quit early for some reason. It was still flying very nicely, so I pulled it up into a wingover. About a 12 kt tailwind as it went over the top, speed dropped below Vmca, and all of a sudden the thing was in a flat spin, dropping straight towards me. Minimal damage, luckily. If I do another one I might rethink the tail surfaces. ;)
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Ah, suggest not trying to do tricks with a CL twin with only one engine running. HH%%
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Ah, suggest not trying to do tricks with a CL twin with only one engine running. HH%%
Is not a flat spin a trick in itself?
(Sorry Steve.)
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Well, I thought it was rather good, once I got out from underneath it!
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... speed dropped below Vmca...
I like that description.
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I like that description.
Do we need a 'Like' emoticon now?
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I never knew that!
Good reply mate.
Chris , here's a video of a Arthur Godfrey and an Eastern Super Connie flying on ONE engine.
The triple tails weren't for looks, but the were very efficient for dealing with asymmetrical thrust!
The engine out demonstration starts at time stamp 6:40
http://www.youtube.com/watch?v=SCL7FglFapY&feature=relmfu
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Chris , here's a video of a Arthur Godfrey and an Eastern Super Connie flying on ONE engine.
The triple tails weren't for looks, but the were very efficient for dealing with asymmetrical thrust!
The engine out demonstration starts at time stamp 6:40
http://www.youtube.com/watch?v=SCL7FglFapY&feature=relmfu
Thanks Doug.
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The triple tails weren't for looks, but the were very efficient for dealing with asymmetrical thrust!
There were several factors that went into the triple tail design of the Constellation. Yes, there may be some advantages to multiple vertical tails in a multi-engine aircraft to deal with various engine out operations.
The Constellation had some design heritage from the P-38 Lightning. The Constellation wing is basically an enlarged version of the P-38 wing in planform and airfoil The P-38 had twin vertical tails (yes, it it obvious that there was no other way to do it on the P-38) so why not go on with the idea of multiple vertical tails on the Constellation. But one of the main factors was the vertical height that would be required with a single vertical tail on this airplane. The basic design for the Constellation was laid out before the war as a commercial venture (involving TWA and Howard Hughes). At the time, the Constellation would have been one of the largest commercial airliners and even with the relative short vertical tails, it was taller than most airliners at the time and few commercial airfields/commercial carriers had hangars that could handle anything taller.
Keith
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There were several factors that went into the triple tail design of the Constellation. Yes, there may be some advantages to multiple vertical tails in a multi-engine aircraft to deal with various engine out operations.
The Constellation had some design heritage from the P-38 Lightning. The Constellation wing is basically an enlarged version of the P-38 wing in planform and airfoil The P-38 had twin vertical tails (yes, it it obvious that there was no other way to do it on the P-38) so why not go on with the idea of multiple vertical tails on the Constellation. But one of the main factors was the vertical height that would be required with a single vertical tail on this airplane. The basic design for the Constellation was laid out before the war as a commercial venture (involving TWA and Howard Hughes). At the time, the Constellation would have been one of the largest commercial airliners and even with the relative short vertical tails, it was taller than most airliners at the time and few commercial airfields/commercial carriers had hangars that could handle anything taller.
Keith
Bingo! It had to fit in the hangar.