SuperTigre GS-40 Problems

by Bill
(Wichita, KS)

I am new to RC planes, I have built a trainer and it is 99% ready to fly.

I cannot get my SuperTigre GS-40 to start, not even a pop. I am working in very cold weather(35-50 degrees daily) and I am using 15% nitro-methane fuel.

I have tried both the standard issue ST glow plug and an OS#8 that I recently picked up.

My starter is an electric drill motor with a .375x8" piece of all-thread with a Rubber plug on the end to cup the nosecone nut.

I turn the engine at 200-300 rpms(estimated) in the CW direction(from the pilot seat view). I routinely check to make sure I have not flooded the engine because I sometime cover the muffler to add some pressure from my (homemade) fuel tank.

I have tried warming the engine with an embossing heat gun prior to start with no luck. I have a glow plug igniter that has a meter to measure the resistance of the glow plug, it shows it to be healthy.

I also check them visually, they glow bright orange. Other than buying a starter, battery and charger, I am at a loss. I have been trying to postpone buying a starter, is that the only answer to my starting woes?

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SuperTigre GS-40 Problems

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Get a Starter
by: Matt

Hello Bill,

You probably should go ahead and buy a starter. They are only about 30 bucks. Most starters generally spin in the neighborhood of 3-4 thousand RPMs.

These engines are touchy, and everybody has bad days when their engine won't cooperate. It's 30 bucks that you won't regret spending, trust me.

You're quite a resourcefull dude! You're trainer didn't come with a fuel tank?

I am assuming you have your tank plumbed correctly. If not sure, scroll down to "Fuel Tank Installation" on this page.

It still seems rather odd that your engine will not even fire at all. Are you sure fuel is getting into the engine? Do you physically see fuel going through the tubing and into to the carburetor when you are priming it?

Who is going to teach you to fly?

I do hope you are getting help with your first flights. I would ask that person to try and get it started with their starter.

I think that's your best bet, but I would still buy a starter if you plan to stay in the hobby. It's just one of those things that you kinda need to have, and they're not that expensive.

I hope this helps,

Let me know how it turns out or if you have any further questions.

Good Luck!

Matt

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re: Buy a starter
by: Bill

I plan to buy a starter, but I am strapped for cash after building my trainer(economy has me scared). The young man that is planning to train me is out of town and I can't just sit on my hands and do nothing.

Sure the starter is fairly cheap, but then there's the battery, the charger for this battery, oh! and a fieldbox to put it all in... next thing you know, I am on my way to burning $150 - again. I really cannot afford to buy all the equipment at once.

My tank will get inspected before flight, I thank you for your insight.

I have also heard of others using alternative types of battery packs that last longer, are lighter to carry and cost pretty much the same. Too many times I purchase the gear, then wish I had made a different choice(This makes e-bay really happy!).

Thanks again for your input...

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Don't have to buy battery now
by: Matt

Hey Bill,

I hear ya about the economy. I think it has us all scared. Maybe it will get turned around soon, after the presidential transition and all. HOPEFULLY!

Anyway, when I first started flying, I didn't have the extra money for a battery either. I barely survived the wife's wrath over purchasing the radio, airplane and engine!

I just popped the hood on my car and used the car battery for several months. It did the trick! My wife actually bought me a battery and field box later on that year for Christmas!

The batteries for the field boxes aren't anything special if that's what you're talking about. If you charge them over night before you fly it will last you all day easily, and that's with using a quick charger for your radio batteries. They will probably last several days if you wanted to chance it.

Just thought I'd bring that up as an option. It's no fun sitting on your hands waiting, that's for sure!

By the way, stop by and let us know how that first flight turns out!

You got a picture of your bird? Love to see it! Post it here if you have time.

Thanks and Good Luck!

Matt

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Basics of starting.
by: Michael from Oz

G'day

To start your engine needs three things - compression, a hot glow plug and a fuel/air mixture in the cylinder.

For years I only ever started engines by flicking them and as a result I learned a thing or two about starting them. This is what I would do to start that engine.

1. Check that there is fuel at the carby. The easy way to do this is to prime the engine by rotating it in the normal anticlockwise direction (viewed from the front) with the throttle wide open and with your finger covering the air intake. As the piston comes to the top of compression take your finger off or the fuel will be blown back by the down stroke of the piston.

Repeat this until you can see fuel in the tubing at the carby. Three or four turns should be enough. If no fuel appears, check the tank and tube for leaks or blockages.

2. Open the needle about 2 to 3 turns from fully closed. This is not critical and should result in a rich initial mixture. When you close it, go gently so you don't damage the needle.

3. Attach the glow heater battery and then smartly turn the prop over while holding it firmly. As it goes over Top Dead Centre you should feel a BUMP as the engine fires. If you cannot turn it over at all, you have managed to flood it and may need to pull the plug out to dry it out.

If it does not Bump, it probably does not have enough fuel in the cylinder to fire. Prime again a couple of turns.

At this point the engine is ready to start - with the throttle at about 1/4 open, a good solid flick (with a glove or other protection) or an electric starter should see it start.

Good luck and be careful - these things can hurt you.

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Starting
by: Bill

The only thing I haven't attempted is feeling for the bump, I will try that today if it warms up enough.

I have also had someone suggest deburring the TE of the prop to lessen any impact. But I'll wear gloves too.

Thanks for taking the time to help...

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Definetely wear gloves
by: Matt

I actually bought a starter with my first engine.

But after it was running, it started so easy just by giving it a flip, I decided I'd just start it by hand.

I was playing around with it in the driveway and the engine died. I turned the prop by hand until it started to get compression, then was going to give it a flip with my bare hand.

I thought my hand was safe because it was behind the blade on its rotation, but it fired BACKWARDS unexpectedly because I had juice to the plug!

Put a huge gash right down the palm of my. I will go to my grave with that scar, lol.

It was an APC prop. I will will admit, I am a wimp when it comes to the site of blood. I darn near passed out from just watching the blood flow. Luckily my wife is a nurse and she happened to be standing there to get it wrapped up before heading to the ER.

I learned the hard way to use either a chicken stick or a starter. At the very least set of thick leather gloves. Do be careful.

Matt

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Starter basics
by: Bill

I think I will get a starter, but I would like one that can convert to carrying a 12v underneath it. For now, I will use my car battery. I do have a great respect for that prop swath, that is why I haven't felt the "bump" yet.

Thanks!

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update?
by: Matt

Hey Bill,

Just wondering if you got that engine going and broken in?

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starter
by: Anonymous

Yes, I did! I bought a starter, and the engine started up pronto! I my car battery first, then realized that I have a "jump starter" that I seldom use. One day I will strap some batteries on to the bottom. but for now the jumper works really nice.

But, you were right about getting the starter. I was just at that point with RC, where my budget was depleted and I needed a cheap alternative.

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Good deal!
by: Matt

That's good to hear!

Have you took your first flight yet?

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