starting an inverted engine
 

i am almost ready to maiden my seabee. but the engine is mounted at an angle so the muffler sticks out the bottom of the cowling. my question is do you have to turn the plane upside down to start it every time? will it not start if the plane is rightside up? any insite on this would be nice. cuz someone told me it will only start inverted!

RE: starting an inverted engine
 

If this engine was run and tuned right-side-up it should perform almost the same inverted. Fuel tank position is the only other variable.

RE: starting an inverted engine
 

i was told it would flood rightside up!

RE: starting an inverted engine
 

Hi mrbass111... I'm no expert, But you should be able to start with the
plane upright... I would not do any primming before starting... Keep the
carb, inlet line mt before starting to prevent flooding. And if your tank
is a bit higher than the carb. It may help by putting a slightly rising loop
in the tank to carb. fuel tubing making the top of the loop close or slightly
above the tank inlet.. Engines that's inverted or angled can be harder to
start due to flooding a higher tank to carb. placement increases this
problem, Too high a tank, then you will most likely have to modify.

RE: starting an inverted engine
 

The only real problem is when the engine (having a glow plug in the middle) is straight upside down and you load it up with after-run oil or flood it through the muffler (hydraulic lock). When it is canted to one side, the plug usually doesn't get squenched in oil if there is a little too much inside.

Be aware of the hydraulic lock possiblity. If there is too much resistance in pulling the engine through compression to prime it, you may have to pick up the airplane and turn it so the muffler is facing the ground, then pull it through gently to clear all the liquid out of it before attaching the ignitor or trying to use a starter. Many connecting rods and wrist pins have been broken due to hydraulic lock and not checking for it, before trying to start up.

I have several inverted engines, both two and four strokes and have very little trouble starting them sitting on the ground. Just don't over prime. Watch the fuel line going to the carb and just get the finger over the carb (two stroke) slightly damp as you pull the engine gently through compression. Then hook up the igniter and start as usual.

good luck.

RE: starting an inverted engine
 

squenched?

RE: starting an inverted engine
 

Sounds as though this is engine is not mounted inverted. If it mounted at 90 degrees (sideways) then there is no need for any special precautions. Actually this is by far the best way to mount a two stroke glow engine as far as operating goes. 1. The carb spraybar is a little lower making it easier to get the fuel tank high enough to center on the spraybar for the best fuel draw throughout a flight. The needle valve is in a safer an far easier position to adjust (straight up) and if say the muffler pressure line is left on during fueling then any overflow will simply run out the muffler and can in no way get up and into the cylinder.

If this engine is mounted with the cylinder at 135 degress with the muffler centered under the engine then getting hydralic lock is a little easier but still not a major problem. The bottom line is any engine mounted fully inverted or at 135 degrees the key is to locate the the center of the fuel tank either level or slightly below the carb spraybar. Any engine that will only start upright or inverted and is subject to excessive syphoning is just a symtom of a fuel tank that is not at the proper tank level/spraybar relationship.

With a fully inverted or 135 degree mount it is always a good idea to keep a hemostat on the feed line if it sits fully fueled in the sun because the fuel will expand. And as always never walk up to either and hit it with a starter without first a few flips by hand and no ignition. If a problem exist it will be imediately apparent.

John

RE: starting an inverted engine
 

The engine on your your Stuka is also set up so that its on an angle to have the muffler come straight out the bottom. I thought mine would be a problem but it starts fine and runs great. When are you going to get yours flying btw?!?:eek:

RE: starting an inverted engine
 

an engine that is mounted inverted anywhere past 90 deg. WILL NOT run the same as an upright engine.hydraulic lock can be a problem but, usually the acceleration and idle suffer severly unless some sort of glow driver is used to assist the plug in keeping lit. occasionally a very well broken -in engine (two stroke ) will run ok inverted but its rare.

RE: starting an inverted engine
 

I have several Saito's [72-82-91-100] that I fly on a regular basis. All are inverted, and I have never had to use an onboard glow. They all transition great. The only different tuning I've had to do was the low end had to be leaned on a couple of them from the upright settings.
When starting for the first flight of the day I put my finger over the muffler and turn the engine over by hand till it sounds "squishy" then a couple of more turns without the muffler pressure. Then I apply the glow heat and flip the spinner backwards against compression and they normally start. .
If I had a very expensive [dollars or labor] scale plane I just might use the on-board glow as insurance.
FEB

RE: starting an inverted engine
 

Most sport engines will run just as good inverted as they will upright or at 90 degrees. For example an OS FX or AX, or a Saito 4-stroke will idle and run perfectly inverted. But this is not true of some "entry level" engines. OS LA engines are noted for having idle problems when mounted inverted.

You do have to be careful not to flood the engine (hydraulic lock) when fueling an inverted 2-stroke. I always make sure that the throttle is fully closed and this helps. Then flip the prop over by hand several times to make sure that it is not locked up before priming or putting a starter to it.

RE: starting an inverted engine
 

thanks for all the tips guys. i am glad that i wont have to start this thing upside down all the time that would have been a pain. fastsky-i kinda put the stuka on the side to get the seabee running. got the canopy painted yesterday so all i need now is to mount the cowling, canopy, and trim it out and im ready to rock. oh!! and i still need to install the bomb drop and servo. hopfully ill get to maiden the seabee this weekend!

RE: starting an inverted engine
 

I have several of these "Rare" engines. Never have I had an issue with an inverted engine. You just have to make sure you have the fuel tank in the right position. If inverted engines were such a problem many of todays models would not be designed for them.

RE: starting an inverted engine
 

MrBass, some engines are easier to start than others, but all will work inverted, or semi-inverted, like yours. You are describing a 135 degree semi-inverted mount. I have had no problems at all starting and running engines in that configuration, & you should be equally successfull --- as long as you use an electric starter for the first start of the day.

RE: starting an inverted engine
 

Almost all of the more elegant control line stunt airplanes have inverted engines. Most people start them with no problem, although a few do turn the airplane over.

Jim

RE: starting an inverted engine
 

I have a Seagull Space Walker 2 that has a TT .46 Pro on it mounted at about 135 degrees (muffler is at bottom). The engine starts with no problems. However, I do not prime it either before attaching glow igniter and starter.

Dave...

RE: starting an inverted engine
 

I've got a bunch of planes with engines that are inverted and at the 135 degree position being described. I never use a starter on them. The first flight of the day I prime the engine by putting my finger over either the carb or muffler outlet. After this I usually don't have to prime. I also have never had one flood. If you think through it, it's actually very difficult to flood an inverted 2 stroke engine. If you happen to get too much fuel in the carb, it's just going to drip on the ground.

RE: starting an inverted engine
 

thats good news. i was dreading the thought of having to start that plane upsidedown in my cradle and then flipping it over upright. there scary enough just starting right side up. thanks again.

RE: starting an inverted engine
 

I have run many 2 stroke engines inverted and and have had no problems. Everything that I have flown had a cowling and I used a Super Fueler. Once the fuel tank is filled I keep the end from my gallon of fuel plugged into the fueler to keep fuel from running back into the carb. When I'm ready to start the engine I just fill the tank, unplug the fuel line, attach the Ni-Starter to your engine and fire it up. The low end on the carb does need to be leaned out a bit but thats just a matter of firing the engine up and let it idle, give it full throttle and see if the transition is good. If it hesitates to full throttle just lean the low end 1/8 of a turn and repeat this until the transition is good. I just finished setting one up the way I meantioned with a fueler and it's running a Super Tigre G90 inverted.

RE: starting an inverted engine
 

I also have to dissagree with Eltigre, any of the model engines will run as well upside down as they will right side up. If there are problems in getting a good idle when running inverted, it is just improperly adjusted, most probably on the low speed needle valve or the tank is badly located relative to the carburator. The main caution in starting and inverted engine, especially the two stroke, is getting a fluid lock by overchokeing or by syphoning fuel into the combustion chamber while the plane is sitting unused.

RE: starting an inverted engine
 

Anyone want to buy a hanger full of RARE engines!!!!!! All mine run inverted, 2 and 4 stroke, and I suffer not 1 iota of any of the "problems" you describe.

RE: starting an inverted engine
 

WELL YOU GUYS ARE DEFFIENETLY WRONG!! many inverted TWO STROKE engines give plenty of trouble FULLY INVERTED regardless of fuel tank configuration. SOME dont run well even at 45 deg. you are trying to argue against plenty of experience over the years with people who have tried it AND FAILED. ask Clarence Lee , ask any of the engine experts. changing fuel tank position may help at one throttle position but it will also affect overall running as the tank runs dry.It has nothing to do with the carb anyway , the plug gets drowned with excess fuel. since you want to play semantic "games" here we're talking transition not just idle or full bore.Four stroke & gasoline engines spark works fine but not T/S. as far as you having plenty of these of these "rare engines"- BULL . its one thing to say it on the web , practical experience is another story.IF AND ONLY IF its well well broken in it may run but transition will suffer to some extent .it has to. if your so confident of your engine in this situation why bother with an ignition assist if its so good?? it wont make any difference (in your opinion) - SOME engine may tolerate this condition better than others but its not recommended and for good, solid, experienced based reasons. you cant help but have problems .& control line is not RC. the controlline engines in that configuration are nearly always started upright with the plane inverted , GEE, I wonder why???

RE: starting an inverted engine
 

BULL you cant help but have problems inverted T/S RC with transition

RE: starting an inverted engine
 

eltigre, it appears many disagree with you. Add me to the list. Perhaps YOU can't get them to run right, but it seems that many of US are doing so.

RE: starting an inverted engine
 

ELTIGRE Since I posted early in this thread I don,t wish to be misunderstood, Please do include me in your list of my fellow purveyors of "BULL" Its amazing to me that so many of my successful aircraft dating back to the mid fifties encompassing a Controlline and RC with a little freeflight thrown in for seasoning were in reality just bull and could not have worked. Pity my memory must be fading.

By the way just as Jim Thomerson indicated (this gentleman knows of what he speaks) Few Ukie stunt flyers ever needed to invert for starting.

Its really simple; in any straight suction or suction/muffler pressure system the key most important factor is the Tank/spray bar height relationship for a successful operation. Now I would agree that with throttled engines there are two types of carburators that can be problamatical with an inverted installation and there is no mystery to it at all; Engines that use a rotating directional spraybar for midrange leaning or any carb that uses a simple bleeder for mid range. The reason is simple these type of systems are not as effective at leaning the midrange area and therefore are a little tougher to get right.

Here are a couple of my most recent additions that have never had a flame out or throttling problems in many flights. Well except with some deliberate ones by short tanking the twin. The single is a Magnum four Stroke and That twin by the way which has TT .46's were installed new after a few runs in stands and they transition just as well as any other of my TT's mostly sideway mount in my pylon ships. I only rarely will use an upright mount because like it or not that orientation offers the least uniform fuel delivery from full to an empty tank of all simply because of the difficulty in attaining the optimum tank/spraybar relationship in many airplanes with that configuration.


So Please, Please include me in your "BULL" list.

John