prop flying off
 

Hello everyone, I went to fly today and I started my plane with the electric starter. It fired right up and I throttled back to much and killed it. when I cranked it with the starter again the prop and spinner broke loose spun around the shaft and flew off[:o] This also happened on my second flight with this plane. I know I tightend it enough. So what am I doing wrong? also, I bought two new props for my plane, both 10x6 one is plastic like the original and the other is wood. What is the real differance between the plastic and wood props? What is the differance between a flat ended prop(both new ones) and a tapered ended prop(the original)? Thanks guys

RE: prop flying off
 

First, what type of engine?

Second, you may have a hydraulic lock - meaning there is too much fuel in the cylinder. The piston comes up and can't compress the liquid, so the only choice is to slip on the spinner or twist the spinner off (Or of course, break the crankshaft or connecting rod).

RE: prop flying off
 

The plane is a Nexstar, the engine is an O.S. 46 F.X.I. that has the restricter on the needle to keep you from adjusting out of optimum lean rich range. (Please don't tell me I could break the crank, my plane is to young to die[:o][:o][:o])

RE: prop flying off
 

First of all, you cannot get a prop nut tight enough by using a little 4way wrench. Get you a small good quallity set of Crescent Wrench, and don't be scared to snug it down good and tight. The Stock Prop nuts are softer than the shaft, so don't worry so much about stripping the shaft. The Nut will strip before you strip the shaft, but with this said you don't want to strip either. If yo are nervous about doing it, then take a torque wrench to the field with you, and have a veteren flyer torque it down for you, and then the next time you will know exactly how far to go. I have been around several nextstars, including the one my Brother owns. It seems they all like to start backwards with that O.S engine, and that stock prop match. I actually find it easier to start his with a chicken stick backwards. Once you flip it this way, it may either start up, and run backwards or it may cough, and kick itself into running the proper direction. If it happens to start backwards just trim the idle way down to a crawl, and then bump the throttle a couple times, and then it will usually cough, and then take off in the right direction. My point is that for some reason this combination just wants to start easier in reverse than forward. So when you are using an electric starter you have the engine wanting to work in the oppisite direction that the starter is spinning, thus trying to spin your prop nut loose. Hope this helps, and good luck with your Nexstar. They are really a good flying Plane.
Ray

I used the word Channel Locks in this Post, and the word I meant to use was Crescent Wrench, so I have corrected that. I would never use a pair of plyers to tighten anything on my Plane, or a cheap crescent wrench. A good quallity one without slop works good. A Bleeder Wrench like posted below would also be good, or the proper size boxed end wrench. My field box is heavy enough, and I just like to carry as many multi use tools as I can without bringing my whole garage toolset to the field. The one thing I can't figure out how to cut down on, is the one whole drawer I have full of Allen Wrenches. It seems that all dozen of my Planes all use different size Allen Wrenches.

RE: prop flying off
 

[quote]ORIGINAL: jnesbitt82

Hello everyone, I went to fly today and I started my plane with the electric starter. It fired right up and I throttled back to much and killed it. when I cranked it with the starter again the prop and spinner broke loose spun around the shaft and flew off[:o] This also happened on my second flight with this plane. I know I tightend it enough. So what am I doing wrong?

>
>What is happening is that the engine is "kicking back" (also called backfiring).
>Since this happened twice in 2 flights, it sounds like your engine MAY be
>running too lean.
>
>The easiest way to check this is:
>
>After the engine is started and the glow starter is disconnected, advance
>the throttle to wide open and point the nose of the plane straight up. If
>there is no change in RPMs, it is adjusted properly. If it speeds up
>and/or dies, it is too lean. You need to open the high speed needle valve
>about 1/8 - 1/4 turn and repeat. If the engine slows down and/or
>"blubbers", it is too rich. You need to close the high speed needle valve
>1/8 - 1/4 turn and repeat the nose up test.

>Things you can do to minimize/prevent the prop from coming loose/off is:
>
>Cut a piece of sandpaper (100 grit is good) to fit between the back of the
>prop and the thrust washer. Have the grit side of the sandpaper towards
>the prop and tighten the prop as usual.
>
>Add a safety nut. This would be a second nut in front of the one that
>holds your prop on and tighten this nut against the first one FIRMLY.
>You may not be able to do this with all spinners.
>

also, I bought two new props for my plane, both 10x6 one is plastic like the original and the other is wood. What is the real differance between the plastic and wood props?

>
>Wood props tend to flex less than plastic props when under a load. The
>downside to wood is they WILL BREAK if the prop has ANY TYPE of prop
>strike. Since you are just learning, I would suggest using a Windsor
>Master Airscrew 11x6 prop. These are the black ones. They are
>substantially more tolerant of a prop strike. Once you have learned how
>to land, switch to an >APC 11x5, 6, or 7. I would not run a 10x6 prop on
>a 46 engine (unless you are racing, but that is another story). There is
>too much chance of the engine over revving due to the lack of a proper
>load on the engine.
>

What is the differance between a flat ended prop(both new ones) and a tapered ended prop(the original)? Thanks guys

>
>The tapered end prop is USUALLY a more efficient prop AND it is a quieter
>prop. Switching from Master Airscrew props to APC props frequently results
>in a drop of up to 6 db in the noise level generated. In many communities
>noise is a major issue and strictly enforced at the flying field.
>

[quoted]

Hope this answers your questions.

RE: prop flying off
 

Actually, part of this statement is wrong.

You WANT the engine to speed up a little when you lift the nose; if it it stays at the same rpm, or slows down, or dies, it's too lean. (Because it's already at peak rpm. The engine will unload a bit in the air, so you don't want peak on the ground.) If the rpm increases you can try leaning it a bit more. If it doesn't, richen it about 400 rpm.
Dennis-

RE: prop flying off
 

Most of the info posted here seems reasonable, but I would not use channel locks to tighten the prop nut. Any kind of pliers will eventually chew up the nut, a wrench is designed to install and remove nuts. Get a real box end or open end wrench and tighten the prop really well. I use a flare nut wrench where possible.

RE: prop flying off
 

When reinstalling my prop, I used a wrench to tighten it. I think I will give that lock nut idea a try. This extra nut on the crank won't cause any problems with the engine will it. As far as the other props, they are what the hobby shop salesman recommended. He said that is what the Nexstar had on it. I should have known better though because he was sold out of 11x6 props:eek:

RE: prop flying off
 

In my previous post I mentioned Channel Locks. I misworded that. What I meant to say was a good crescent wrench. Thanks for pointing out my misinformation.

RE: prop flying off
 

If you are using a plastic spinner and a starter, it's gonna happen alot. I got tired of it and went to dubro spinner nuts and aluminum spinners. the plastic ones flex too much from the torque of the starter

RE: prop flying off
 

I do have a plastic spinner on it and it has only happened when using the electric starter. After putting a lock nut on it that should stop it from backing off, right?

RE: prop flying off
 

Everyone has thier opinion, OK ?

I believe in things being tight, but somewhere, something must give. If your starter battery isn't hot enough and fuel collects in the cylinder, a hydraulic situation can occur. The answer isn't just tighten everything, you can bend your connecting rod or wrist pin . Sure. Make sure your prop is tight, but also treat the cause and not the symptom. Engines do not normally kick back that hard. When they do, something is wrong. Such as a cold starter battery. An inverted engine will do this because fuel collects. A good engine, broken in properly should start with a bump of the starter or a flick of the prop. Plastic spinner will not cause your prop to come off.

1.)Are you holding the starter on the engine for long periods ?

2.)OR is the prop kicking off immediately ?

If 1, then your battery is cold. The engine isn't lighting. Fuel collects until it is full and can't compress it.

If 2, engine is flooded, fuel is pouring into it. This could be that the tank is too high. Or the engine is inverted. Or the engine is mounted sideways, but with the head aimed slightly downward.

RE: prop flying off
 

Ckangaroo - I have always tightened by props with 4 way wrenches when possible (some engines nuts are too large and do require the monkey wrench). I have been flying 2 strokes for a long time and I have never had props fly off. Although I don't deny that a spanner would be the best, it isn't necessary.

jnes - first I wouldn't use a wood prop if you're a beginner. Plastic is much more durable and easier to keep tight. Then, I would check the following.

1. Are you using the provided washer and nut? You need to make sure that the washer is used in conjunction with the nut.
2. Have you overtightened the spinner to the point where the self tapping screws are too loose and the spinner can be nearly pulled off with the fingers?
3. (As kingwoodbury said) Check for hydrolock by taking out the glow plug and pouring out excess fuel. You can check the plug by plugging it into your glow starter and seeing if it burns bright red.
4. Are you under he age of 10 so that you cannot apply enough force to secure the bolt (serious)
5. Are you starting the starter first then smashing the head into the spinner? Don't do this... it's not safe. Always turn the prop clockwise (by using the starter head like a finger) until you feel compression and then push the starter cone onto the spinner. Last press the starter button to flip it over.

I thought I'd have a lot more "checks" but that's about it.

"This happened with my second flight..." You're already flying this thing with the prop flying off? Honestly, I think you are just not tightening it enough.

RE: prop flying off
 

When I went to start it today I didn't have any problems with the prop coming off but it just would not start with a chicken stick so I had to use the electric starter. After doing about three qwick burst from the starter, I removed the glow plug, turned the engine over, and didn't have any fuel come out. I then started to rotate the prop by hand looking at the piston. After about the third rev, the prop started hanging up. I kept turning it but every few revs the prop would still hang up. Is this where it is still new? The motor only has about 7 flights on it. Another thing, the fuel I started to use said not to use after run oil. Should I heed to this advice?
I have used after run oil up till now.