mpriestley

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Hey guys, I have two questions, need help.

1st. I have 2 flights on my Magnum, LOVE IT, but I can not get my engine to die in flight (on the ground I can get the idle to shut down but in the air I bring my idle down to kill it and I still end up with my prop spinning (engine with slight idle) on landing,
(I did make sure that the barrel is completely shut)
I do not want to balance a prop for every flight!

2nd, CG question, I did balance my plane I believe at 140mm per some of the suggestions here. however even with the aft cg I still had to put a lot of up elevator trim to survive the first flight. I added 1/4 oz of weight to the tail and second flight was better but still needed about 5 clicks or so of up elevator trim (from center) Is it possible that the plane is still nose heavy or is there something I am missing? It seems like if i do add 1/4 oz I will be able to have my elevator level with the rest of the stabalizer (ie. no trim necessary)

could there be any other explanations? or suggestions?

The most fun/dollar I know of!

Rudeboy

Check your wing incidence... If the wood gets compressed at the rear of the wing you change the incidence slightly, and it could be enough to cause what you are experiencing.

When I cleaned up the wing saddle I also changed the incidence slightly (by accident)... My wing now has a very slight positive incidence and I have to trim down now... My mistake, but it is not enough to make me redo the entire thing.

Again... at these speeds everything has to be 110% correct, or you get things like this. Even an incidence change of 0.1° can cause considerable trim changes...

mpriestley

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Rudeboy, I think you hit the CG prob right on the head. I do have a bit of squeeze on the wood at the back of the wing sadle where the nylon bolts go.

Now my question is this: how do I fix it (do I just loosen the bolts a bit?) , and for the next flight should I just leave the balance the way I have it now?, Or should I expect such a diff that It might become too tail heavy?

(I just put my wing bolts on snug but the wood back there compresses very easy)

any ideas on the idle kill prob. (I can't run out of fuel where I fly because if you do not make the runway you rarely get another flight, we do not have any emergency landing areas at my flying field.)

MMallory

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A wood shim should make up for the wing issue.

Your carb/engine sounds like it has an air leak somewhere. Check all of the bolts and make sure the carb is tight. If necessary put fuel tubing around the needle to seal that as well.

Rudeboy

Idle problem: make sure your carb fits tight, press down firmly before you fasten the bolt. Also, I kill the engine about 100 yards before touchdown because it just doesn't stop immediately when the plane still has considerable speed. But if your not sucking air from somewhere it should stop within 1-2 seconds...

I wouldn't fly around with the wing bolts not tightened properly... no way!!!
When I was still using the metal bolts, one came loose in-flight... I immediately moved on to nylon wing bolts

I filled up the wing joint with something called TEC-7: it is a multi-purpose glue that looks a bit like silicone... it even comes in tubes like silicone...

If you don't want to redo the entire wing saddle, then at least fill up the wing bolt plate so it's flush with the fuse sides... that should be enough to keep the wood (wing) from compressing. You could use some epoxy mixed with micro balloons. Don't hold the wing down with the bolts when the glue is setting, or the fault will still be there after the glue has set. Just hold the wing down with some weight... half a pound or so should be enough to hold it in place without compressing the wood.

Rudeboy

A wood shim like MMallory would also work, but make sure the incidence stays correct. Sand, measure, sand, measure, sand... and don't be impatient...

mpriestley

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Sounds like my problems are fixed,

Thank you for the advise guys!

Cactus.

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fly the tank out you wimp


bwt... wet show, a Magnum was left standing around, next it flew a bit funny, when he landed he found the PVA used in the ARTF for that tail had gone soft and he had inflight variable dehiderial!
keep them dry boys

mpriestley

My Feedback: (1)

Well, I knew it was only a matter of time....

I actually expected Rudeboy to chime in on that first!



Just to clarify, the magnum got wet and the tail went soft?

Rudeboy

Oh, I thought about it... don't worry... But I was able to restrain myself... I must be in a mellow mood or something...

I thought PVA glue was supposed to be water resistant? Are you sure it is PVA?

Cactus.

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well... i aint sure what it is, but as far as i know, pva isn't water resistant.
it wasn't just ,ohh a shower...
it was sitting in the rain for a hour or so, in this time i lost two rx's and a elevator servo in a Cougar, not sure why i lost a dry servo.. tho the bottom was a bit clammy.
i even got water in the ailerons!
anywhos... his tail went soft yes. the wing CF sheet also came off right over the patch, nice sound, nice black fltter, no problem

Dangerous Dan

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What speed should I expect with a Weston Magnum with a Dub Jett .46, with full length tuned pipe, tuned by the manufacturer to swing an APC 8 3/4 x 9. It supposodely turns this prop over 20,000rpm static?