Hi Y'all,

Other than providing extra room for a muffler, is there any advantage/disadvantage to tilting an engine 45deg rather than upright, 90deg or inverted? Seems to me it would tend to make the plane more heavy on the side to which the engine is tilted.

Thanks Guys,
Sonnytex

I cannot think of any thing wrong with the engine being mounted at a 45 degree angle. As for weight on one side being a little higher, I would say that is correct, however I do not beleive that it is anything to worry about. Good Luck, Dave

The big advantage to tilting the engine 45 degrees is when the engine is inverted. It minimizes pooling of the fuel which will cool off your glow plug making starting extremely difficult.

My P-51 PTS came that way, and I fly my ModelTech Extra 300S with an inverted engine at 45 degrees.

( You didn't specify upright 45 degrees or inverted 45 degrees... )

I haven't had a problem with either. Nothing different in terms of weight too.

Upright you would still have a bit of weight on one side due to the muffler, etc. which is easy to offset by moving the battery pack to the other side.... no biggie.

If you change the angle that the engine is fitted away from the original then just make sure the tank is lowered/raised to keep its centre line close to the level of the carb barrel.

David, Campy, ophose & Downunder,

Thanks guys - it all makes good sense (never thought about the fuel pooling). Oh, I did forget to say which "45", on the upright side of 45degrees. I did ensure that the thrust lines were maintained and carb is about 3/4 fuel tank high.

Sonnytex

An engine tilted down 45 degrees places the muffler outlet near (or below) the bottom of the fuselage so that little exhaust residue hits the plane. I have not used this but have seen photos of planes set up like this.

G'day Mate,
No problem at all, as long as the tank level is correct, see pix.
It also places the muffler dead centre, under the plane.

Even at inverted (which most of mine are), as long as the fuel tank has been lowered, no problems.

Hi Sonnytex,
I have used a 45 deg inverted setup. No problem at all. The exhaust exits between the undercarrage legs and if you fit an exhaust deflector (45 deg rubber fitting) this sends the exhaust gunge away from the model. Always good, I Hate cleaning airframes at the end of the day.
An upright 45 deg tends to be used on high wing trainers, to stop the exhaust gunge hitting the wing.

At the end of the day you can mount the engine at any angle to assist the installation, ie throttle linkage, tank height, cowl limitations.

There is no wrong, just remember, prop to the front.

Thanks to you all - I mounted my .46 os ax at 45degrees toward the right wing on my Magic 3D. Still have some work to do on it but should have it flying in a few days. Thanks again.

Sonnytex

PS - Bigfoot "prop to the front"? Now I have to go and turn it around again - well, there goes my CG again.

I have never been able to get an inverted engine to run & transition reliably with out glow assist.regardless of tank position. some would not run well even at 45 deg.

It makes no difference in what angle you mount the motor. It will run just as well in any position if you have the tank properly placed relative to the carburator and have the mixture needles properly adjusted.

Yeah, the engine will only become a bit more intolerant of inproper needle settings, but over all the difference is miniscule.

Tank height greatly affects flooding out the engine though.

A uniflow setup also seems to help if you are having problems.

The majority of my engines are inverted.

sorry to disagree but what you say IS NOT TRUE. IT MAKES A He**of a difference with some two stroke engines & im speaking from experience over years with a number of engine brands & sizes in positions from vertical to 90 deg to fully inverted to every angle in between. the reason is simple . the head acts as a "sump" to pool fuel regardless of the carb mix, location & settings. it has nothing to do with carb location.IF the engine is very well broken in you might get away with it & even then there will be some hesitation but you cant help but experience some pooling. also in some scale planes you have little choice as to tank location . you MUST use a glow assist. In 90 deg position there is no problem however, using pitts muffler in tight cowl ive noticed considerable changes in settings due to heat soaking.

Over the past year I've broken in 8-9 new engines, all inverted.

Other than the noted siphoning issues, and slightly more intolerant needle settings, they run w/o problems.

This includes OS, Evolution, Supertiger, Magnum GMS & Tower Hobbies engines ranging from 2 stroke .46's through BGX-1's and four stroke 1.80's.

None run with glow assist, though I had purchased an on board ignitor to handle my Evolution 1.00NX.

My Evolution 1.00NX was the most intolerant of the inverted position, but I'm glad I mounted it that way. Mounting it inverted and my frustrations with it this way resulted in my eventual replacement of the carb, which cured all of the problems I had with the engine.

It ran fine inverted once I resolved the problem it really had.. I never did install the on board ignitor.

Better that I find this out on the ground, rather than in the air with the plane inverted or on it's side.