new experement
 

Hello guys

it is Elvir from Croatia, I am coming to the states this Christmas and want to do a new plane . here in Europe there is not that free access to stuff as in the states , my question is for the twin and 4 engine flyers, I wanted to build a 4 engine plane that was made of two tower uproar 60s . With 4 gms 47 to power it with an engine sync to control it , dose any one have any ideas of that plan. Or do you guys thin that will work. I an looking for it to fly ok , some small acrobatic nothing to extreme. any ideas pleas Wright them i would appreciate it.

RE: new experement
 

should be ok think it may be a bit overpoered.

RE: new experement
 

Definitely overpowered.

I was thinking of a similar design but to use my 4 OS 25FXs for power, 2 of which are in my twin Uproar based on the 40 sized plane.

The thought was to use a similar twin-boom design with a set of nacelles on the wing. The engine separation on the pictured model is 11 inches and the span is 50 inches.

RE: new experement
 

Thank you for your replies, I wanted to do a twin or even a 4 engine for a long time I love the sound . I have a 65 in boat with 2 j&g motors and they sound outrages. Here there is no one flying a twin so I wanted to do some thing extra. I built I cmp corsair with a Zenoah 20ei. And I crashed it three times because of the retracts. So I put it on the shelf for a while until I design a new set or get the new ones from robart. Now back to the 4 engine, how dose your twin fly using the upros 40. I was planning to go to about to 90 to 100in wide wingspan, I have no experience designing planes. I was talking to a friend and here in Croatia before I came here my friend was flying with his home made planes , with his own designs , nothing was available not even balsa , they would go down to the market to get wood boxes for fruit to build planes with the wood they found there and go to Italy , but that was expensive for them.. I would send you a picture of my friends own design of a twin but i cannot figure out how right now. I told him about my idea and gave me a suggestion on like you twin plus a center motor and a motor directly in the back of the center wing as a pusher. Any more input I would appreciate. To get an idea of what and how to build it. I wanted to surprise my friends here when it is done. i got it here is my friends own twin with one mds 45 and a supertiger 45, and my corsair.

RE: new experement
 

Here are a few drawings please let me know what you guys think I took you recommendations at about 11in centre for the motors dose it look like it is flyable and would it be safe. Please sent you input. Thank you again .

RE: new experement
 

if the drawing is to scale on the 4 on the wing draeing it appears the outboard ingines are too close to the tips,you may want to increase the span.usually engines do not go beyond the midpoint of a wing panel

RE: new experement
 

Elvir,

It will not be over powered. The size of the planes we normally fly makes the next size engine down too small and under powered for a twin. It also makes a twin constructed by just adding 2 nacelles too heavy. I have or had both types. I am also flying my 24th twin with a mod to a triple not counted.

The best twins I have flown are those with 2 fuselages and a short center section added to the wing between the fuselages. My two twins have spacing or 14" and 13". the closer the spacing, the less problem you have with an engine out. I like your idea of the twin fuselages and the pusher-puller center pod. This keeps the engines closer to the center.

The yellow, black & white plane is a Tiger 2 (40 size) with 2 OS .46AXs. It flew fine, but was heavy and landed fast. The twin fuselage plane is a World Models Sky Raider Mach II with 2 GMS .47s, replaced with 2 OS .46AXs. It was a pound lighter than the Tiger 2, flew better and landed slower. The red Stin Stick is an ARF (2 GMS .47, replaced by a second pair of OS .46AX), but it had the wings lengthened to match those of the 60 size single. It was also a pound lighter than the Tiger 2 and flies excellent. The white, red & blue twin fuselage plane is made from 2 Phoenix Models Sonic 25 kits. Power is 2 OS .46LAs which don't weigh much more than a .25 or .32. I enlarged the ailerons and rudders and it flies well.

Here are some hints.
1. Fly the engines on a single first and get them broken in and set.
2. Tune each engine individually and shut down to tune the next one. When all are set, crank all up and fly.
3. Do not adjust an engine with others running. You will invariable set it wrong.
4. Run them slightly rich. If you aren't leaving a smoke trail, you are too lean and one will probably quit.
5. I have not had the best luck with GMS engines on a twin. I generally use OSs on twins and my GMSs in singles.
6. Run a fuel filter.

If you run a synchronizer, use it on the outboards and leave the inboards or pusher-puller alone.

RE: new experement
 

The twin Uproar is a blast to fly. It has a super fast roll rate and strong on vertical performance (not unlimited but plenty)

I did some math for another inquiry about the design comparing the separation on the smaller version compared to the 60 size. It is right in line with Ed's recommendation of engine separation. "The 11 inch separation is 22 percent of my 50" span (of my design), 22 percent of your 65" span (the 60 size) would separate your engines just over 14 inches if you decide to go that route."

If you were going to use 40s on a twin version of the Uproar 60 I would use the above example. If you would use 4 engines on the 60 size I would reduce the engine separation, that way the nacelles won't be so close to the wingtips.

There are a lot of ways to approach this as I have thought about it quite a bit. I'm interested to see what you come up with!

RE: new experement
 

Thank you all for you input. I am still not sure which way I will go. But thank you for you math lesson for the spacing. I had bought a few Gms 47 for some friends here in Croatia that I picked up I Austria, and they are incredible here, it will finger start with the first flip right out of the box. But the big problem here is fuel. One friend if running on local home brew and it dose not run good. The rest buy 7% high power at 23 us $, when we get a chance to go to Austria. And cool power 10% is around $30, and it runs grate plenty of power and can idle down to about 1100 rpm on good fuel. also the drawing are not to scale , so i under stand about not going out to far with the uoter enging , if any one is not so busy could you give me an idea of how wide to make the wing span if i am 14 in wide on the spacing. my origing thought was i would go between 90 to 100in wide is that to much.

RE: new experement
 

if you guys are intrested i have a small clip of my capracorn 65in deep vee with twin j&g motors runing at http://www.youtube.com/watch?v=2CYN0xIJTYA