Dear All,

finally got my Topstar-60 (essentially Phoenix clone of U-Can-Do 3D or Twist-3d) in the air today. I am using an OS 75AX on the same and it is currently installed inverted (Head downward) as per manual. Some one suggested to have the engine installed at atleast 90Deg as installing inverted gives performance issues. Is this true and what other problems can I have with the engine inverted?

Also, in my second flight I had a deadstick and landed calmly. Was this cut-off due to the inverted engine? I was at about 40% power at that time straight and level having just finished a roll.

Since I am one man team at field, taking the booster off once the engine has started is an issue. Am currently thinking of installing a four-stroke type remote igniter off the receiver battery which I will switch off once the engine is started.

Ameyam

I haven't had any problems with 2 stroke glow engines mounted past 90 degrees or inverted.
Make sure the fuel supply line at the tank is at the same level or prefferably a bit lower than the
fuel inlet on the carb. I have 6 engines of my own setup inverted ranging in size from .25 - 1.60.
on my first inverted setup a .61 my tank was higher than my carb and the only time I had a problem
was during fillup the carb would drip fuel on the the table, and continue to drip while sitting (3 line tank).
My remedy was to close the high speed needle and count the turns when closing, then after refilling I would
re-open the needle. I did this for about 20 flights and got tired of it so I lowered the fuel tank. problem
fixed.

The OS should not give you any problems inverted. I have an OS 1.20 AX inverted on an Excelleron 90 pattern plane and it starts and runs just fine.

The engine quitting could be several issues. How far back is the tank from the engine? Did you have the mixture set right? Was it to lean or to rich (most likely to lean)? The pressure from the tank is something that you have to make sure about.. are you using the right tubing? Is the tubing on tight? It could have come off during flight, too. I've done that and never noticed it until it happened on the next flight. It got airborne, but it quit pretty quickly after that. It will draw on it's own but really needs pressure to maintain.

I've never needed a remote glow igniter and I have three OS 1.20's, and two OS .75 AX's (as well as other OS engines of different sizes). I also have a 1.60 but have not yet run that engine.

CGr

Hey Chris! Heard you are getting married soon.

Did you fly anything today?

I'm working on a Furious flat-out. About 50% done.

Dick.

Hello dick.

Yup, getting married in October. No flying today, I was at straw with Carl and Bob on Sunday.
it was nice to get to the field, No flying for me but I did some calling. I am working on my 50cc
Extra and a Ultra stick 120 with Quad flaps and MDS 1.48 2-stroke. I should be flying the big
stuff some time next month. Right now I am just playing with the foamys.

I install my engines at 135* so the muffler exits centered with the bottom of the plane. Very easy to hide, and deflects all the mess away from the plane.

The idea of an engine running poorly inverted I believe has to do with the glow plug being perfectly upside down such that fuel entering the engine will flood it. With a good plug, proper tank position, and a properly tuned engine, I don't think this would be an issue. Going out on a limb here, I bet that those who do have issues with inverted engines have one or more of the above setup incorrectly.

Nah. My Exceleron is exactly upside down and it runs just fine.

You can also use a hotter glow plug if you so desire.

Chris, I take it you managed to get to the field.. last time I was out, I had trouble getting to the field let alone on the field. It was pretty mucky.

I've got three electrics and one glow to maiden. Today would have been nice. Not a breath of wind. Jeech.. but had to take the Volvo to the dealership in Cherry Hill for service... found out I had a bad tire. Cost me $250 before I was out of there. Jeech.. always something. Went for an oil change and ended up... well, you get the picture.

Later.

Joe,
in my very short time with planes I found that tuning and startup procedure is the key to starting and keeping
an inverted engine running. When starting alot of the problems I see are due to overpriming. I usually
do 3 flips with carb at full throttle and finger over exhast (on tank pressure system) then close the carb and
attach the igniter and hit it with a starter or back flip. On pumped engines, carb open 4 flips carb closed
and back flip with igniter on . Getting too much fuel into the engine drowns the plug. after 1st flight I kill
the engine with the TX (close throttle trim) and I don't need to reprime the rest of the day. When I tune engines
I make sure they are a few clicks rich, but never sloppy rich, I found that if you run them too rich they load up
easy and have a tendancy to oil foul the plugs when they are sitting.

ha ha I thought that's what I was trying to say; set up the engine properly, tune it properly, prime it properly, and it should be fine

One major issue with the inverted engine is getting to the booster once the engine starts. To do this you have to reach under the model which means some one has to pick it up. I dont want to depend on fellow modellers each time I start the thing and there are always chances of accidents when two people are on the same model.

While seting up the plane, I noticed that the tank outlet was inline with the crankshaft. But at full tank, the carb still drips fuel. I am going to get my instructor to review it. In any case, inverted engine inside cowl means I cannot get to the head to scrub it (with soap and toothbrush followed by full drying with hair drier) after flying ends for the day. Since I am using 20% castor, this means that the inverted head will gunk out quickly and overheat and hence I feel that it should be mounted atleast 90Deg.

The engine probably cutoff as it was too rich. We didnt actually run-in the engine much on the deck, we were still running-in it in the air, so it was very rich anyway. In the few rolls prior to the dead-stick, I did notice the RPM starting to drop (from the sound) so I resisted doing loops. I think this should resolve once at full power, first 4-5 flights will be heavily rich. In any case, being a 3d-capable plane, the Topstar flies slooooowly (you know what I mean) so can be flown and landed leisurely even in dead-stick.

As of now, I dont have my own vehicle. I take to the field by Cab and / or usually with someone who can give me a lift. To save weight, I dont have a foam stand and electric starter and I start by hand. Having started with CI engines my flicking technique is well developed and I have had hardly any knuckle raps in the year and half I am flying (that doesnt mean I am not cautious).

Ameyam

http://www3.towerhobbies.com/cgi-bin...?&I=LXBC35&P=7
you can mount the remote portion anywhere on the plane you like. I have mine mounted on the side of fuse
just behind the cowl. that way I don't have to reach under the plane after starting.

I have a brand spanking new one, still in the wrapping, sitting on my bench. I was going to use it on that Super Star/OS 1.60 whenever I get around to finishing it. It comes with it's own NiCd battery.

CGr.

Dick,
I'm telling on you!!!! extra battery in the plane = more weight.

OK, this addresses the issue of remote igniter, but the issue of inverted engine from performance point of view and from gunking point of view remains. What do you guys do regarding the gunking? Is there some way to avoid it? As per the RC Magazine, OS recommends that AX series engine fuels need to have atleast some percentage of castor, so even if I move to 10% synthetic-10%castor mix, gunking will still occur. And will that inverted mounting hurt my engine in any way?

Ameyam

Checked out the tank position today and its outlet is above carb inlet level. However there is no way to correct this since the hole for fuel tubing to pass through firewall is above that level. Instead, I looped the tubing in such a way that it is raised above the top of the fuel tank and then back down to the carb forming a siphon. Wont this prevent the flooding?

Also, the fuel tank on my plane is old and I can see some dirt floating around inside. Is it a good idea to install an inline filter such as the Great Planes inline filter at enggine suction? Will this reduce the amount of fuel entering the engine causing cutting out?

Ameyam