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        Short Tail or Long Tail? Whats the difference?

#1 lmopar69 Dec 06, 2005 04:39 PM

Short Tail or Long Tail? Whats the difference?
 
I know ALOT of you are very smart about this stuff, so here goes.
I am putting together another plane from my crazy ideas and was wondering about this:

First off, the wing span is 6.5 feet, and the elevator is 20 inches wide.

How will it "react" if I make the tail really close to the wing... like 20 inches or so, vs if it is farther back, like 48 inches, or even farther?

In other words, how does a plane handle with a short tail vs a long tail? What are the "Pros and Cons" of each?

Thanks,

Laine

EDIT: There are pics of it on page 2 & 3 now.

#2 lrsudog Dec 06, 2005 05:21 PM

Longer tail moment tends (everything else being equal) to make a plane maneuver more smoothly for a given control input. They can also get away with smaller flying surfaces usually.

Of course, the opposite tends to be true as well; shorter coupled aircraft tend to be more maneuverable, but may require larger tail surfaces.

#3 wattsup_kz Dec 06, 2005 05:24 PM

The tail length greatly affects the CG as well.

#4 lmopar69 Dec 06, 2005 05:36 PM

Thank you! I guess that makes pretty good sense. Kind of like a "lever" type idea. Duh! Shoulda thought of that.

So, what would you do, go short or long?

Either one might be fun. hmmmmmm, decisions...

#5 Tram Dec 06, 2005 06:38 PM

The longer it is, the more stability you will have.. but several have already said that. :)

#6 Silent Dec 06, 2005 06:42 PM

I like more manuevarability. :)

#7 lmopar69 Dec 06, 2005 06:56 PM

I think Im with you Silent. I will make the tail short and big and see how I like that.

#8 Tram Dec 06, 2005 07:05 PM

78" span with a 20" elevator.. Hmmmmm... :)

Is this thing going to be electric?

#9 lmopar69 Dec 06, 2005 07:17 PM

Yup, right now Im thinking twin motors. S400 direct drives maybe? 2 outrunners? hmm, I dont know, might try both. Dont really know what will work, but I will find out.

This will be the second life for this wing. I chucked the rest of the last plane I had it on. Didnt really like the way it flew. Guess I will see if I like the way this one flies, or, maybe, IF it flies period.

#10 Cubber Dec 06, 2005 07:38 PM

Quote:

Originally Posted by lmopar69
So, what would you do, go short or long?

You'll notice that most 3d planes, those that loop on themselves have short tails. Large pattern planes on the opposite side of things, designed for precise loops that take all the sky, have very long tails, fuselage on them most often longer than the wingspan. That should give you a clue.


Now besides this... simply design the plane to make it look good to your liking.

#11 lmopar69 Dec 06, 2005 07:49 PM

Quote:

Originally Posted by Cubber
Now besides this... simply design the plane to make it look good to your liking.


LOL, not sure it will look good or not, but it will be rather different I suppose. Im using the wing from the plane in this video... (but putting much larger ailerons on it) http://www.rcgroups.com/forums/showthread.php?t=441643

with two carbon fiber booms (not decided on length yet) going back to a 24" x 6" tail (3" of it elevator) with zagi-like winglets on the sides of the tail.

might be a little "goofy" looking, but hey, maybe it will fly good. Maybe it wont. :D

I will probably have the booms run forward of the wing also and mount twin motors on the front of them.

Why? Why not! I gotta be me.

#12 lmopar69 Dec 06, 2005 07:53 PM

Ooooh, I wish I had a couple BIG EDFs layin around... THAT would be cool!

#13 lmopar69 Dec 06, 2005 08:08 PM

Ok, while Im at it, I have 2 direct drive speed 400 motors that came with a couple Great Planes Slingers i used to have. First off, can I run them as "tractors" or do they have to be run as "pushers"? If they can be run as tractors, any one care to help me guess what props to run? I dont think I have any props except some 5x5 pushers, and I dont think those will work.

Dang, I was hopin to have this done and fly it in the AM sometime.

#14 Skrogg Dec 06, 2005 08:13 PM

Tail is tail :)
Sorry Mopar i had too...
And whenever I have a set flyn time it rains or the winds are over 1000mph (thats 11mph to us stick pilots)

#15 wattsup_kz Dec 06, 2005 08:15 PM

If they are 6v motors, and you are running them on 2 cell lipo or 6 to 7 cell nimh, a 6X3 prop works well. That's how my Terry is set up. 1 motor and 16oz AUW.

Brian


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