tbonebrown

Hello folks,

I'm new to this hobby and have hit a wall for ideas. Seeing a wealth of knowledge out here on the forum and thought I would pick your brains for some help. I had a buddy try out my Parkzone F4F Wildcat the other day and he crashed it pretty hard, nose first. After inspection here is what I noticed immediately:

1. one wing split in half about 3/4 of the way down.
2. cowl was broke into pieces
3. the prop was bent up
4. Engine mount was cracked

Thinking it would be just an easy fix I bent the prop back...taped the wing real quick and threw it back into the air. Here is where it got interesting. There was really no power at all. With full throttle the plane would barely climb. I immediately brought it down for landing and brought it back to the "shop" for some home repairs.

I ended up putting everything back together via epoxy and it looked like it should work. I am waiting on a new cowl so that is the only thing that's really missing from the plane. I'm assuming it can fly without the cowl but I'm not sure what the issue is now. When I went back out today to fly it, same thing.....seems like it's running at full throttle and feels like there is quite a bit of thrust in my hand but the plane just does not want to fly when I put it in the air. I'm okay with it not flying true and gliding well but there is NO POWER at all. It can hold itself up but it won't fly more than a quarter of the air speed it used to.

[*]Is it the cowl affecting aerodynamics that much?[*]Speed control got messed up somehow and not allowing full throttle? I used an RPM meter and it's spinning at ~15K RPMS...with the stock 6x9 prop. Anyone have this plane that may by able to tell me what you're spinning at please?[*]Does the prop need to be replaced as it was bent up a bit?[*]Did the epoxy affect the weight that much? I used about a ketchup packs worth to do ALL repairs. I'm ordering new watch batteries for my scale so Imay compare the new flying weight to the manufacturer's specs but those wont' be here until Tuesday.[*]Did I get the mount engine mount off so much that it affected the torque or somthing like that? I noticed it's off center and pointing to the right a bit but I think that is natural for prop torque, correct?[/list]Any thoughts? Any insight or suggestions that you may have are welcomed and much appreciated!

Also, sorry for the long post but thought it may help to be as detailed as I can be right now.

Thank you, I look forward to your replies and suggestions.

T.BONE

Sir_Sparksalot

My Feedback: (8)

Hey tbone,
You might want to make sure the motor doesn't have any damage. Too, if the prop was beat up it can cause a severe imbalance problem. This would be pretty bad because it could damage the motor to a greater degree. I don't think that little bit of epoxy should have caused that kind of problem, but it would be good to get a few more opinions before replacing the plane. Also, if the prop is flexing while spinning it would cause a significant loss of air speed. The diameter of the prop would not have the same amount of surface perpendicular to the fuse. Thus a good reason for the loss.
If you have a new prop, that would be the first thing I would try, along with making sure the motor is in good shape.
And yes, it is perfectly OK to fly without a cowl. We glo junkies do it all the time when we are testing a new plane. In fact I have a number of planes w/o cowls. Specifically an UltraStik and a trainer. I also have a profile plane without a cowl. They fly pretty solid. True, a cowl might help the trainer, but it is just a durable plastic version, made such for the likely crash of a newbe.
Eric

tbonebrown

Thanks Eric!  I'm thinking the prop maybe my culprit.  It's not as stable as it once was and maybe that's where I'm losing all my power.  I'll swing into the LHS and try to get a new prop tomorrow.  

tbonebrown

Also, good to know about the cowl, thanks again Eric!

tbonebrown

It was definitely the prop.  Thanks for the info Eric!