when i connect the glow heater to my engine and bring it up against compressin it wants to jump back the other way in my hand. im not sure if that is hydrolic lock or what please help.



zack

Well first of all WELCOME TO RCU!

Now, your problem could be hydro lock.. what does it do when you take the ignitor off and turn it over? If it does the sme then it's hydro lock.. If it doesn't then it could be trying to backfire..

A little more info would let us narrow it down even more..

I think you have what we call the "bump". It tells you there is fuel in the cylinder, the plug is hot, and the engine is ready for you to start it.

Jim

thank you when the glow plug is taken off it does not do that anymore. a bump sounds kindof like it what is a bump?

First, a safety comment. I hope you are wearing a really thick glove when you're doing this. I also hope you have the plane firmly immobilized so it won't jump forward when it starts. Props are sharp and hard. As many can attest, you can get a good rap on the knuckles, or worse, a really bad cut, when the engine kicks back while starting. It's safer for a beginner to hand start with a chicken stick instead of their hand. Many would tell you to stop doing anything by hand and just use an electric starter. I'm not one of those, but I'll say be careful, and you should find someone locally who can help show you the safe way to start an engine. There's 101 little safety things that experienced people do without even thinking about them. You'll either learn them by experience (ouch, better not do that again!) or from someone with experience (less painful, and much less dangerous). Let someone with some ouches save you from having to lean by personal experience.

Ok, now that that's out of the way, as has been said, you are getting a bump. A bump is a little kick back on the prop when you bring it through compression. It's often used as a signal that the engine is primed well enough to start it. Briefly, here's a typical starting sequence (hope I don't leave anything out):

Begin with the glow driver OFF the engine, and throttle opened to full.

Put a finger over the carb, or end of muffler if cowling or engine orientation prevents access to carb.

Being sure to keep arm away from prop arc, flip engine through compression several times. The goal is to use suction (if finger is over carb) or pressure (finger over muffler output) to get some fuel into the carb.

Remove finger from carb or muffler, move throttle to idle, and attach glow driver. A brief note about glow drivers. I use this term to mean the all in one unit with connector and rechargable battery, a wire connected to a 1.5v battery, or a wire connected to the glow driver output of a power panel. The power panel is my favorite because it gives you an adjustable output so you can get a nice strong glow.

At this point, some people will FIRMLY hold the prop and bring it through compression. Did I mention, keep your arm away from the prop? This does two things. If the engine is mounted inverted, it confirms that the engine has not become flooded. It also lets them feel for "the bump". If you get a bump, the engine is telling you it's ready to start. If you don't get the bump, some people will remove the glow driver and prime a little more.

If you got the bump, or don't want to check for one, the next step is to flip the engine through compression several times, until it starts. If it doesn't start, or show any signs of firing, remove the glow driver and prime again.

A few more safety things to remember.

Some engines, when already warm, have started even without the glow driver. You should assume that any time you move the prop, the engine could start. This means keep all body parts away from the prop and make sure it's not going to be able to move when it starts.

I've found that the metal to metal connection between glow driver and glow plug can create little blips on the radio, which can open the throttle a bit. Once the engine is started, and until you get the glow driver removed, assume these little blips can happen and stay clear.

Once the engine is running, do the rest of your work, removing the glow driver, adjusting the needle valve, measuring the RPMs with a tach, etc from BEHIND THE ENGINE. Do not allow any part of your body, or anyone else's, to be in the prop arc. If something causes the prop to fail, you do not want a body part to be in the way of the flying blade.

Hopefully I got all the major points. It's still best if you work with an experienced person who can watch you and help save you from some ouches.

Oh, and welcome to RCU! There's lots of great people and great information here. I encourage you to learn how to use the search feature. There's a huge amount of information already out there and you can often get your answer faster by searching.

That "Bump" is the engine doing exactly what it's designed to do... It's exploding the fuel. But since you're turning it slowly, it's exploding before the piston passes top-dead-center, so instead of kicking the prop forward, it's kicking it back.

Had you given the prop a good flip with a chicken stick, instead of bumping, it would have started (Or at least, it would have ran till the prime burned out)

And welcome to RCU!

thank you every body. i would also like to know is it entirly necisarry to have a spinner or spinner nut on the airplane?. i just broke mine and wont get to go to a hobby shop for a while but want to fly my plane. also i never have used a tach. should i?

youngpilot - you are asking quite dangerous questions. turning props slowly while the glow is lit, flying with or without a spinner/spinner nut... spinner broken without first flight... i think you need professional help (not the psychological kind :-) but really bring it to the field, LHS or friend that flies. i'd hate to see you get hurt. and listen to the advice here... it's right on the money!

in answering your question, you don't need a spinner as long as your prop is secured with the correct washer and nut. for 2-stroke engines that would be the washer and nut that came with the engine. for a 4-stroke that would be a washer and a nut/lock nut combination that also comes with most fourstrokes. The spinner nut can be used to replace one of the nuts. of course, if you were originally flying with only the washer and spinner nut and the spinner nut falls off, you clearly cannot fly. if you are flying a 4-stroke and you were flying with a washer a prop nut and a spinner nut, flying without the spinner nut may be okay for smaller (30 size) engines but do NOT try that on a large 4-stroke engine especially a Y.S. they will throw the prop with any level of detonation.

I had always heard that AMA required either a spinner or a rounded prop nut, and that leaving the end of the shaft exposed was not acceptable. I looked at the AMA membership manual, but could not find specific words. The closest I could find was "Refrain from using a pointed spinner, propeller fasteners,...". In the interest of safety, in case the plane hits someone, you would be better off replacing the spinner, with either a new spinner or a rounded prop nut, before you fly. I'm pretty sure some clubs will not permit someone to fly without a spinner or rounded prop nut.

Hmmm, never seen any regs on a spinner myself.

Lets see, whats going to be more dangerous, getting hit with a 2-1/4 inch spinner, a 3/4 inch rounded nut, or the end of the crank shaft with a nut.

Doesn't really matter, they are all going to do damage, I think the spinner would make the biggest hole. [X(]

Either way, keep your fingers out of the prop and get help if you can. If not, make sure someone is helping hold the plane at least.

well you guys are great help. but i just wanted to let you all know that i have a good idea at what i am doing. i have been flying for two years now. and i do not belong to a club because the closest one around me is all electrics or gliders. the reason that i asked about the spinner is because i really wont have the chance to buy a new one for a while becuase i dont like makeing small orders from tower hobbies. thank you though. oh and the bump problem was becuase i had always used a starter and never used just a chicken stick and i think because on all my other models the engine is upward on my kombat 40 it is to the side

really though thanks for all your help i really apreciate it