Hi all,
         does anyone know of a reason beside cosmetic that a two stroke IC engine should NOT be mounted sideways?

In other words does the run suffer? Rear muffler setups foul the tank placement? Etc.

I can only see pluses but sometimes I can delude myself quite easily too.

Thanks.

(Oh, the engine that I am looking at for sideways use is the 51 R&B Metamorph, that snazzy offset muffler will adapt quite nicely to run under a tank methinks.)

Vibration problems
resonance problems
header/muffler/tank problems
cg problems
these are just some of the problems some people have ran into with side mounting.

If you want to make a true inline design with retract gear then the sidewinder motor would be good, make sure you have a strong fuse.

Some people have made the side mount work, but it does present more problems

Randy

Ok, I will pick on vibration/resonance. Why would mounting an engine sideways make this problematical?

The metamorph will have no issues clearing the tank but I fully admit that many other designs will need difficult workarounds though.

The vertical CG , surely this is simply a matter of positioning the engine in the right position to suit?

Just as profiles vibrate more in the side to side, or horizontal direction ,so do built ups, the reason is many of them..not all.. are stiffer in the verticle plane and are not as stiff in horizontal, or side to side
This is not something I will argue, as it has been well documented that many have had problems with this, even Bill Werwage had these problems with 2 of his stuntships. and another top placed stunt flyer had problems but solved them by flying much faster than normal. There is a very well known RTF that has problems from side mount, even if some will not admit it.
You will have to be sure to calculate where the CG is and set the engine and wing in the exact correct place, it maybe good to have an adjustable leadout guide that will go up and down as well as front to rear. Then make sure it is built very strong/stiff in the front. When you can feel the buzzing and vibrations all the way down the lines and in the handle you have a problem.

Randy

Hey Randy,
                thanks for getting back to me, and it occurred to me postmortem to do a search on this and I consequently learnt a little more.
I 'get' that the primary vibration is strongest along the pistons plane and laying the engine down will normally place that shifted plane across the narrower nacelle sides instead of vertically along them.

So its something to watch out for.

Interestingly the 51 Metamorph has a 6 suspension points in which to mount the engine and given in the brochure that came with it is the reasoning that a broader footprint lessens the transmitted vibration and it should shake the model less than an engine using only 4 points on a narrower footing.

Andrew,
             yep, know all about Freebirds mate and again the PAW 40 diesel that is specified for that model has a very long and broad mounting lug system.
So perhaps this is key to success here?

Thanks guys.

Hello Chris,
I use an MVVS49 diesel mounted sidewinder and that doesn't have  much of a mounting footprint. However the MVVS doesn't vibrate as much as the big PAWs.
If you have a box type fuselage, then there should be no difference in structural rigidity if the bearers are horizontal or vertical. In either case they are mid point in the box fuselage, so I don't see why mounting an engine sideways should have any differece in the vibration mode of the "box". After all we are not talking profile fuselage here. I am quite willing to be corrected on my assumption.
  As far as I can see, the only drawback is that the tank is between the bearers on a sidewinder mount and that hardly matters as it is easy to line upp to the venturi.

Regards,

Andrew.

Hey Andrew,
                    I have 2 PAW 40's, MVVS 40 and 49 both of which sport diesel heads and I have spent much time discussing the penultimate diesel stunt model, the Freebird, with one of Tony Efflienders team mates - so I know a little bit about side winder problems.

What I am really asking about is glow engine run problems more than structural considerations, and although the two are intrinsically connected I think that I know enough to separate them apart.

Diesels, indisputably prefer side winder setups. But two stroke glows, I don't know and the lack of models, plans and advice of this is telling.

Yatsenko and Lauri Mallila (sp?), and the odd large profile model like the Cardinal are the only examples that I have seen to date.

Only one way to find out for sure I guess and its just that the R&B 51 Metamorph 'looks' as good a candidate as any to try this out on with its massive footprint and wonderfully flexible exhaust arrangement.

Talk soon, Chris.