582 high engine temp

by Michael Regan in 2 Stroke Technical Questions 11 years ago

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Re: 582 high engine temp

by Michael Regan » 11 years ago

Michael Regan

5 96 0

Ahhh... a picture paints a 1000 words. I see my mistake in the pictures where blade 3 is actually 1 deg more pitch at the 75% mark as well as the tip. This old bugger needs a new pair of glasses. Would you fly with this man? There is no pic of the tip measurement as I needed an extra hand that I did not have spare lol.

Some may say ... well you are at the max recommended pitch, so you can afford to reduce it... but wont this also reduce my cruise speed if I do that? Not trying to have my cake and eat it too, but if pitch was the problem, can anyone tell me why the rpm was ok before (twice)?

Back to the fuel problem for me. Oh man, what a headache! This topic is about into its 7th page now and must be frustrating for some. It bloody well is for me I tell ya. All jokes aside tho... its been very educational for me and maybe for some quiet folk out there watching also.

mike

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Re: 582 high engine temp

by bill martin » 11 years ago

bill martin

10 757 0

Mike,

If you are getting the same pitch at the 75% station, that little variation at the tip. won't hurt. Its not uncommon with wooden props.

Always take "recommended" pitch angles with a grain of salt. That all depends on the prop, the plane, the altitude, and most importantly, the engine. With two cycle engines, prop load and prop load alone determines the max rpm. Even a badly tuned engine will easily exceed its rpm limit with an unloaded prop. Inversely, a perfect engine will never reach max rpm with too much pitch.

Forget the numbers and take out two degrees of pitch and see what happens. If your engines recommended max rpm is 6700 wot, set the pitch so you are getting about 6500rpm wot on the ground. You will probably see very little difference in cruise speed at the same rpm. Even if you do have to up the cruise rpm slightly, you will probably see an improvement in fuel consumption because at the reduced pitch, the engine is not working as hard even at the slightly higher rpm.

An engine that is overloaded with too much pitch will also run hot.

Bill.

Thank you said by: Michael Regan

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Re: 582 high engine temp

by Dennis Richardson » 11 years ago

Dennis Richardson

1 153 169

Hi Mike
Glad to see that you are looking at the prop. Your photos indicate a variance that is beyond spec, once corrected I am sure you will notice a difference. I would like to see you go farther with your inspection. Make sure that your pitch measurements are taken at exactly the same distance from the end of the blade, don't be satisfied with the fit of that tool, fit it onto pre-measured marks. I suggest 3 locations.
Ensure that all blades are fully seated prior to any measurements.(you pull them out to seat)
Check tracking and outer swing diameter of each blade.
Check the gap between the two hub halves after it has been torqued to the proper values. This should be .030"
Inspect the surface of the prop blades for any wear or failure of the exterior finish.
My main concern is the blade clamping, if the hub has ever been over-torqued and the roots ends are compressed, then the blade holding ability of the hub is compromised. If you see any variance in the diameter, measured at the tip of each blade, or the tracking of the blades combined with a less than acceptable air gap in the hub halves then over-torquing is the probable cause.
If the finish on the blades is not perfect than humidity can be a problem. If moisture is allowed to penetrate any or all of the blades than you will have balance and warping issues.
If everything checks out then you need to set the pitch, with a little practice you will find this is easy to do. Although GSC says within 1/2 degree is OK I don't agree. The closer to perfect the better, you will be able to feel the vibration from 1/2 degree in pitch variance.
I would suggest starting with a static setting of 6250RPM. This should allow you to see 6500RPM on climbout.
6500RPM is the maximum allowable continuous RPM for your engine. You should see something just under 6800RPM WOT in level flight
Pitched to allow 6500 on climbout should give you the best performance and fuel economy throughout your speed range. Performance will suffer if you allow it to rev beyond this point and the engine will suffer if it doesn't reach 6500.

Dennis

Thank you said by: Michael Regan

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Re: 582 high engine temp

by Michael Regan » 11 years ago

Michael Regan

5 96 0

Thanks Bill and Dennis.

Have since discovered more probs with the propeller. I have uploaded a short video (sorry about the freakin wind noise) which you can see here...

http://www.youtube.com/watch?v=4xllJokhenU&feature=youtu.be

One side of the prop clamp half has only 010 gap and the other side has none at all, and also the bolts are loose.

I guess the question is... can this be fixed or will I need to get a new one?

Also check out the crap I drained from the fuel tanks in the pic below. I did what John M said and removed the elbow and flushed the tanks. The good news is that both filters inside the tank were clear of rubbish.

Mike

FuelDirt.JPG (You do not have access to download this file.)

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Re: 582 high engine temp

by bill martin » 11 years ago

bill martin

10 757 0

Mike,

The gap between the hub halves is no problem. Just go to your local building supply store and pick up a roll of aluminum tape. The type that is used on insulation. Or you can use stainless steel leading edge tape. Or you can use aluminum or brass shim stock. Shim stock is best. You can usually buy a roll of thin aluminum roof flashing which works as well as shim stock. Cut a piece to fit around the clamping base of each prop blade. This will allow you to fully torque the blades and still have a gap between the hub halves. The amount of gap is not important as long as you have some gap after torqueing.

This is a very common problem with wooden adjustable props. They will compress and shrink over time. Just build up the base of the prop with shim stock and you will be fine. Try to use just enough to bring the gap close to what the hub manufacturer says it should be. Bear in mind that it aint rocket science and it doesn't have to be exact.

One tip: Don't use plastic tape or duct tape. It sticks to the prop hub and makes it hard to adjust the blades.

Bill.

Thank you said by: Michael Regan

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