We still have snow up to our butts and I'm bored. Checked around the shop and found a couple of OS 55's and a Senior Telemaster kit along with some fuel tanks and landing gear. Got me thinking, and my wife hates it when I start thinking. I'd like to turn this Senior into a twin. I've never bashed a twin, all my twins are ARF's.

I got the plan pretty much on paper but I'm stuck on one key item. Thrust offsets. The Senior single plan has several degrees of down thrust which I'll need on the twin configuration (I'm assuming). But, what about the side thrust, depending on what thread I read some folks say no side thrust others say a few degrees out on each side while others say only a few degrees out on the right motor.

I'm also taking most of the dehedral out of the wing. Plan shows roughly 5 degrees and I'm changing it to one degree. Think thats a good idea?
Appreciate all the great advice you guys always have, Jerry.

Out thrust is a good plan in any twin and will contribute to the survival of your airplane. (progressively less important as you ad more engines). Four your project I would use four to five degrees out thrust. That is typically what I use on my twins except for on which is fully adjustable fro zero to 10 degrees out thrust. This one I taylor for the skills of the pilot I am helping to make a transition. My four engine bashes are two degrees out on the inboards and four degrees out on the outboards.


I just completeed a six engine bash of a Senior Telly and its quite successful so far after two test flights. I used no down thrust and stock stabilizer to wing decaledge. The underwing bathtub nacelles raised the thrust line vertically reducing the need for down thrust. Also I fly the airplane at 25% MAC. This is much further forward than the spar. Plans call for flight at about 33% and this is to far back and will present control problems as a multi.

The wing D tube forward of the spar is sheeted to the wingtip to eliminate torsional weakness.

Do not eliminate Dehedral completely as this will be too much and it makes the likely hood of propellor ground strikes more pronounced in a less than perfect landing. I reduced my dihedral to about two degrees and yes this is a good idea. Too much dihedral and the airplane becomes very unresponsive in roll. This has worked well in my other twin and four engine bashes.

John

Thanks John. I built the nacellles this weekend and put two degrees down in them since the plans reference three degrees down for single engine flight. My nacelles will be similar to yours. Maybe I need to reconsider the down thrust given your very detailed response. What about the standard right thrust built into planes? Should I go 4 degrees out on the left and six degrees out on the right to provide the standard right thrust that you would typically build into the plan?

I'm a little lost in your CG response. You are saying that with the engines closer to the CG the CG should come forward versus what is on the plan for the single engine setup?

I do appreciate your response and your six engine Tele has to be a record for the number of engines on a Tele wing! I'm playing with this Senior Twin design as a start to a Tele Giant Twin in the future. A couple of 40cc gas engine on the Giant would be neat. I have a Giant that I fly and just love the thing.
Thanks, Jerry.

Please take good notes, and pictures, and drawings of what you do.

A twin STM is on my list of projects, and I know of another RCU subscriber as well.

Good luck with your work....

Spent some time building this past week. The TeleTwin is beginning to take shape. I thought I had a Senior Telemaster kit but come to find out all I had was some plans in a box. So I scratched together some extra balsa and begin building the twin. Started with the stab. The stab on my last Tele was one of the weak parts. I beefed up the stab by sheeting the leading and trailing edges and cap stripping the rips. I also built up the elevators instead of using flat stock. I also added 3" to the vertical stab and doubled the rudder size to accomodate better rudder control in the event of a engine out.

The nacelles are built of 1/8" lite ply with 1/4" ply firewalls. The accomodate a 10 oz tank and the throttle servo. The nacelles are removable and self contained such that I can work on the motor, throttle servo or fuel system without wrestling around with the wing. The nacelles are attached via 3/16" dowels in the leading edge of the wing and a 1/4" nylon bolt in the real of the nacelle that goes up into the wing.

To ease transportation I built a center wing section that mounts to the fuselage via 3/16" dowels in the leading edge with 1/4" nylon bolts in the trailing edge. The center section is 28" wide to accomodate the nacelles and 2" of prop clearance from the side of the fuselage. I took most of the diehdral out of the wing. I used 1 degree of diehdral on each side when building the center section. This section is built up from the original plans by using 3/32" sheeting and doubled up spars. 1/8" shear webbing was installed front and back of the spar. The wing halfs were joined using a 1/2" x 3/4" ply joiner that was 16" long. The nacelle area has a 1/4" ply plate where the nacelle bolts to the wing.

The sheeting is not complete in this pictures but does give you an idea of how this section is contructed.

Wow! Seems everyone is building a twin Tele. I'm still working on my V-tail twin motor STM ARF. I hope to fly this weekend single motor to make sure the V tail is working then it's on to modifying my wings for the motors. I'll be using two Scorpion 3026-12's turing 13X10 E props for about 550 watts per side.

Well going electric would allow for a much less robust wing and there is tons of room for batteries in the fuse. I've got the H9 B25 in electric and waiting for battery charging is a pain but it sure is nice to leave the field with a clean airplane. BTW, the H9 B25 has outboard thrust on both engines. I've put 3 degrees of down in my nacelles per the plan for the single engine Tele and then I'm going 4 degrees out on the left and 6 degrees on the right. Total expierment at this point. Thanks, Jerry.

Charging at the field isn't really and issue for me. I have two 3s 8000 mah packs, which on the single AXI 4120/18, would get 30 min of flight time on one charge with throttle management. Three 10 min flights is about the limit on this bird because I fly other stuff also. Yes it's really nice not having the fuel in the car or on my bird. I planned on putting some down thrust on each side. I'll have to look into the out thrust also. I had planned on doing all of that with shims on the mount. Seems every time I try and do something with angles I screw it up. You should have seen how long it took me to get the V tail right!

The TwinTele continues to take shape. Fuselage is complete, center wing section, nacelles, and all electronics are complete. Nose wheel seems weak, may need to replace that with a more robust setup. Installed a Sullivan glow driver and mounted batteries in the nose section to achieve a reasonable balance prior to the remaining wing section being added.

looks outstanding JB. If the nose wheel proves troublesome try a Fults type. I have one on my Quad Kaydet and it works well: http://www3.towerhobbies.com/cgi-bin...=RF&search3=Go

Got a break in the weather and took the TeleTwin for a test drive. Flew better than I expected. Way more power than it needed (even at my 5k foot altitude). Single engine performance was excellent. A little rudder, reduced throttle and no problem getting back to the field for a smooth landing.