superdave118

i am considering taking a ultrasport plus and modifying it for a twin. i am conserned though because this is my first time trying to bash a kit together and was wandering how you keep the center of gravity in the same spot with another engin out in front of the wing. do you all thing this can be done. i was thinking of using two .46 engins.

William Robison

My Feedback: (3)

David the 118th:

If you insist on bashing the Ultrasport, easiest thing is two complete fuselages a la F-82. Build a straight wing center section, and make the stab cross between.

If I may suggest an alternative, and most particularly if it will be your first twin (not just your first major bash) you consider the Duellist from Pica, or the Northeast Aerodynamics "Twin-Air 45." Both are single fuselage, with the engines in wing mounted nacelles. The Twin-Air is the easier build, the Duellist kit is slightly cheaper. I have both. The twin-Air is also a bit easier to fly.

This help?

Bash a twin?
. Kit's no sin.

Bill.

JohnBuckner

My Feedback: (1)

Yes Dave it can be done and should work well. I have done a number of bashes although not that airplane. The thing to remember is you control the length of the nacelles for the conversion and the engines will be further aft on the twin than the single. You may have to do some shifting of servos and batterys but nothing major. None of my conversions have been difficult to balance.

John

Homebrewer

My Feedback: (8)

I bashed an ultra sport .60 into a twin with two .40 FXs.
It flew incredible fast and was a lot of fun.

I don't know what the wingspan is of the US + but if it is smaller than the US .60, you may want to use a .40 or smaller engine. .46 engines would be too much in my opinion.

Mendes

My Feedback: (1)

Two .25 FX's would be plenty for this plane, but if you really want more power go with a .32 SX or a Thunder Tiger .36. The wing is built very light on this plane, you will definately need to add reinforcements.

I would think that you are going to need a big chunk of lead in the nose to balance properly. My US+ with an .80 4 stroke balanced perfectly. However this plane does have a very wide CG range so maybe it wouldn't be too bad.

I think the Pica Duellist would be a better choice too though.

MinnFlyer

My Feedback: (4)

I always wanted to twin an Ultrasport, But I agree with Homebrewer, two 46's would be too much.

twinman

My Feedback: (2)

I did the twin bash on an Ultra Sport 1000. Went from ST 3000 to two ST .90's. Lengthened the wing four inches, added 50% larger ailerons,and rudder. Added wing plates for extra lift.
I balanced it by making the engine nacelles much longer than needed. Mount the engines to the firewalls, but do not mount to the plane yet. Pin and move the engine assemblies forward and back to get the balance and glue.
I also added carbon fiber strips to the wing so that I would sleep better.
Goes straight up and does a mean inverted flat spin.
Good Luck,
Told you twins make you crazy.

AmishWarlord

My Feedback: (5)

Looks good Twinman. I got my Ultra Sport 1000 kit in a few weeks ago. I'll be turing it into a twin after I do the Cloud Dancer. Are the 90's doing good on yours?

William Robison

My Feedback: (3)

AWL:

If that drawing is an acurrate rendition of your bash it's going to be a bear with an engine out. Move the nacelles in as far as you can, and make the rudder larger.

If you have built a model of your avatar (F7F Tigercat) and had an engine fail you'll know whay I mean.

With two I'll fly my Tigercat,
. With one it comes down "Lickety-Splat!"

Bill.

AmishWarlord

My Feedback: (5)

na just a quick 1 min sketch I did a few months ago. I will how ever be useing that nose. Some peoples noses are too pointy. :P

William Robison

My Feedback: (3)

AWL:

If you're talking about Twinman George and the picture in post #7, I am forced to agree. Sorry, Mr. Lumpkin, but that's just my opinion.

A thorn is like a long pointy nose,
. Nicely rounded, pretty like a rose.

Bill.

twinman

My Feedback: (2)

WELL I like that nose!! Oh well, that is what makes this fun. I told you that twins make you nuts!!!

Suggestions for the conversion.
1. As I said, build the plane complete with nacelles less the firewalls. Pin the engines, bolted to the fire walls, to the walls of the nacelles to get balance. This leads to less balance weight for flight. Then glue in place.
2. The rudder needs to be much larger. I patterned mine after the ultimate biplane. A big improvement!!! Need pull pull system and high torque servo.
3. Go to two inch full length ailerons. Warning, watch out for flutter due to speed. I ended up with two servos per aileron.
4. Use two servos on the elevator, one on each half, and separate control.
5. I would suggest a small strip of full length carbon fiber on top and bottom of the wing.
6. I added four inches in wing span and wing plates on the end of the wings for more lift and better knife edge. Yes, knife edge!!
This also gets easier if you mix the engines to the rudder. The mix also helps with inverted flat spin due to differential thrust. Now, you worry about getting out of the flat spin, no problem!!! Reverse the rudder and the engine thrust reverses....instand out of spin!!
7. Do this with two stroke 90 size engines and fourteen inch props. Unlimited vertical and performance, including hover!!!
8. Make sure that you can clear fourteen inch props, at the main fuse, by no more that 1/2 inch to aid single engine flight. Yes, it will fly on one engine fairly well....does snap in a loop, but you cannot have everything!!!
9. Ever consider smoke?? Put the tank and pump under the large canopy.......maybe times two? No, I did not think of it until after I built the plane.
Good luck,