I'm sure this has been asked many times, thanks for answering it again. What are the pros and cons of mounting an engine horizontally or inverted, vs. mounting it upright? Are there any specific characteristics about running the engine that change by having it something other than upright?
Thanks!

I mount my saito's horizonally so that its easy in most designs to get the fuel tank in line with the carb. I have run my big saito 180
inverted and another saito 120 inverted but both of these had on board glow drivers.
I think side mounted just looks better than being mounted upright.

Jim

If the muffler/airframe design permits 'sidesaddle i. e. cylinder horizontal pointing to the right, is the most trouble free and safest method.

with this orientation fuel flow is never a problem, none of the flooding problems of an inverted mount or the fuel draw problems of the upright mount (some designs are impossible to get the fuel tank high enough). Also safety is improved, in the case of a conventional needle with it sticking straight up it is a far more natural position for 'tweeking' and the glow connection pointing to the right is far more conductive to safe operations than sticking straight up. The inverted mount is worst of all in this regard unless a remote connector is used and that opens the door for additional reliability problems.

John
Just what works for me

IMHO

Upright: Looks dumb; works great.

Side saddle: Looks good; works fine.

Inverted: Looks great; can cause starting problems; nose-overs on paved runways can be tough on cylinder head.

They say upright is best but I've had great luck side mounting engines to. Inverted can cause many problems, including making it hard to start, not want to idle, tank position too high, and positions the cylinder for damage during a bad landing.

-Bob George

Just for the record, almost ALL of my glow engines are mounted sideways.

Let me ask you this, then, this is for a kyosho Spitfire ARF. ( or BARF, Minnflyer )
The thrust line is toward the upper right corner of the firewall, if facing the firewall straight on. How can I center and lower the engine better, so that I can mount it sideways? How would I calculate the amount of sidethrust I need to build in to the engine mount to make it work? In fact, is that even the right question to be asking? After reading the responses, I'd rather not mount it inverted, even though the directions have it that way.
Thanks.

ULOT

Funny you should ask. Two years ago I prepared two Keosho ARF Me109,s for my teamate and I to race in the mini reno warbird pylon race venue. This ship is very close to yours in most regards and the plans did indeed call for an inverted layout. Because the event called for a rather stringent scale judging which accounted for half your score as well as the racing score we elected to go with an inverted mount to preserve scale outline. We used throttled Nelson Q-500 engines with the only exposed part being the tuned pipes along the belly and took a mild hit on scale points for this.

In this case I,d like to say they were a total success but was not to be. Because of the attendant problems all listed above and others we both had experianced failed heat starts a number of times in several different events.

In hindsight and I were going to use your airplane for sport flying I would go with the side saddle mount and a 'pitts' muffler. Using this type muffler and the cylinder head sticking out the right side will eliminate any thrustline problems and you will be able to go with a stock thrustline.

By the way I think you will enjoy the airplane. It is a delightfull flyer, easier to fly than many warbirds both the Spit and the 109 possess excellent ground handleing and T/O characteristics.



John

UOLT,
I'm not sure I understand your question. The engine should be centered on the thrust line. Whether the engine is mounted inverted or sideways, the thrustline won't change. Imagine the engine mounted inverted as per the plans. Now imagine holding the prop, and rotating the engine 90 degrees. That's the position you want it to be in. The top of the engine mount rails (Bottom of the mounting rails of the engine itself) are on the thrustline of the engine.

I think that will be the solution, I'll grab a pitts muffler for it. I had hoped I was done spending money on this plane, but that sounds like a good investment. Since you mentioned other kyosho warbirds, let me ask you this. It doesn't mention putting epoxy/tape on the wing seam. Is it safe to presume the joint is strong enough without it? Also, how do the wing hold down bolts not vibrate loose? It looks to me like a metal bolt into a metal blind nut. The kyosho instructions are so poor, I am trying to sort it out as I go.

Thanks.

ULOT

It would probably be a good idea to use a thin strip of glass around the center section. In the case of the racers I had slit and lifted the foam for eight inches along the bottom spar and laid in carbon fibre tow. This was due to the expected extreme 'G' loads. For sport flying that is entirely unneccessary but a little glass in the center is cheap insurance.

Good that you reminded me about the fine thread metric wing bolts. Please don,t fail to replace them with 1/4-20 blind nuts and nylon bolts. The supplied bolts will back out every time in fact I lost a Keosho Spacewalker one time by using them and watched the wing descend by itself!

If your ship has some of the expensive machined clevis' with set screws these are also a failure waiting to happen.

If you deal with some of these problems I think you will love the airplane. Best of luck


John

if the rails of the motor mount are to be along the thrustline mounting an engine upright or inverted, how do you orient the mount correctly if mounting it sideways?

outdoorsman

If your model has those hardwood or plywood motor mount rails that are built into the fuselage, you're better off mounting the engine as instructed. Modification is not impossible, but if you're not sure what you're doing to begin with, it's best to stick to the plans.

Most, if not all, commercially available engine mounts have a symmetrical mounting bolt pattern, which mean you can orient the mount in all 4 directions without redrilling holes on the firewall. Also the the thrust line typically stays the same.

Another thing I'll add is that while "side saddle" has many advantages, it isn't without drawbacks. Here are a couple:

1. Doesn't work well on models with cowl cheeks. You'll have to cut a big ol' hole.

2. With a conventional 2stroke glow engine, the side exhaust muffler hangs down at the bottom. This, IMHO, is worse than an inverted engine hitting its head on the ground on a nose over. I've seen many a muffler (including one of mine) mounted this way crack or break off on a hard landing.

I still think side mounting is ideal in many situations. Just didn't want the sidesaddle picture to get painted too rosey.

has anyone experienced the extreme vibration out of the saito
100 mounted out on the nose of a ultra stick 60, just thought maybe there was some kind of special antivibration engine mount
thanks jb