Crooked Engine??

DadOf3 · #1 05-29-2005, 08:08 PM

I am now mounting my cowl on my 7a and I am quite concerned. When I run a string from the center of the top skin to the middle of my prop, it shows the engine to be very crooked. I have verified that the motor mounts are correct and tight, and the engine is centered in the mount. The correct washers are being used. Every thing is according to vans prints. The back of the engine starts out right of center line (looking from the prop back) and ends up just about centered at the front of the propeller. The string shows it all. Is this a normal Lycoming characteristic? If not, I am clueless on what could be wrong. The only reason that I noticed this is because I had a 1/16" larger gap from spinner to cowl on one side? HELP!!

Bryan
RV7a Finish Kit

L.Adamson · #2 05-29-2005, 08:29 PM

Quote:

Originally Posted by DadOf3

I am now mounitng my cowel on my 7a and I am quite concerned. When I run a string from the center of the top skin to the middle of my prop, It shows the engine to be very crooked. I have virified that the motor mounts are correct and tight, and the the engine is centered in the mount. The correct washeres are being used. Every thing is according to vans prints. The back of the engine starts out right of center line (looking from the prob back) and ends up just about centered at the front of the propeller. The string showes it all. Is this a normal lycoming characteristic? If not, I am clueless on what could be wrong. The only reason that I noticed this is because I had a 1/16" larger gap from spinner to cowel on one side? HELP!!

You must have never built radio control airplanes!

The engine is offset to the right, looking from the cockpit, to help counteract the left drift tendencies. Torque, prop slipstream, P-factor

L.Adamson

edit-spelling

DadOf3 · #3 05-29-2005, 08:36 PM

Quote:

Originally Posted by L.Adamson

You must have never built radio control airplanes!

The engine is offset to the right, looking from the cockpit, to help counteract the left drift tendencies. Torque, prop slipstream, P-factor

L.Adamson

edit-spelling

Thanks for the reply. No this is my first plane, No remote controls under my belt either. I must really be screwed up then, because mine (looking from the cockpit is offset to the left and angles to the right (toward centerline) on the foward end. I am guessing that this is normal and they angle it so that the center of the spinner will be in the center of the plane. If this is true, then everyone must have the issue with a larger gap on the left side of the spinner / cowl???

BRYAN
RV7A Finish kit

L.Adamson · #4 05-29-2005, 08:45 PM

Quote:

Originally Posted by DadOf3

Thanks for the reply. No this is my first plane, No remote controls under my belt either. I must really be screwed up then, because mine (looking from the cockpit is offset to the left and angles to the right (toward centerline) on the foward end. I am guessing that this is normal anc they angle it so that the center of the spinner will be in the center of the plane. If this is true, then everyone must have the issue with a larger gap on the left side of the spinner / cowel???

BRYAN
RV7A Finish kit

That's correct. The back of the engine will be to left of center, looking down from the cockpit, with the prop on the centerline. This action pulls the plane to the right, to offset the built in drift to the left. Some plans and builders offset the vertical stab for the same purpose.

P.S. --- I have an RV6A that's about ready to fly, but the cowl is off at the moment. Seems like this gap difference is built into the cowl, but now I'm not sure.

DadOf3 · #5 05-29-2005, 08:50 PM

Thanks al lot. I was worried that I screwed up royally. Now I can get on with my Memorial weekend RV charge to the finish line.

Bryan
RV7a Finish kit

P.S. Reply to you P.S. I have tried everything to take out the gap and it just screws up everything else, I am going out soon to fit the lower cowel. so unless I hear differently soon, thats the way it will stay unfortunatly. I don't like it, but I see no good way around it.

Thanks again

L.Adamson · #6 05-29-2005, 09:03 PM

Quote:

Originally Posted by DadOf3

P.S. Reply to you P.S. I have tried everything to take out the gap and it just screws up everything else, I am going out soon to fit the lower cowel. so unless I hear differently soon, thats the way it will stay unfortunatly. I don't like it, but I see no good way around it.

I just went out & looked at the top portion of my cowl, as it's standing on it's end. It's the older gel coated (white)polyester cowl, and has a definate longer lip on the left side right behind the spinner. Just guessing, it's about a 3/16" difference.

edit again.

If you do have a gap when the cowl is centered side to side with the spinner ---- fiberglassing can do wonders. I've re-shaped the cowl slightly with heat, and filled in gaps, plus added 1/4" to the back of the bottom cowl that I cut too short during the fitting process. In the end, it all again looks original.

DadOf3 · #7 05-29-2005, 09:16 PM

Quote:

Originally Posted by L.Adamson

I just went out & looked at the top portion of my cowl, as it's standing on it's end. It's the older gel coated (white)polyester cowl, and has a definate longer lip on the left side right behind the spinner. Just guessing, it's about a 3/16" difference.

Well, You are right, I just studied my cowl a little closer and there is definetly a built in difference, but not quite enough. If I make the adjustment to get all spacing equal as looking back from the front of the spinner, then the 1/16" extra gap is there. If I adjust to take out the gap, then the spinner / cowel side to side alignment is thrown off. Bummer.

DadOf3 · #8 05-29-2005, 09:20 PM

Quote:

Originally Posted by L.Adamson

edit again.

If you do have a gap when the cowl is centered side to side with the spinner ---- fiberglassing can do wonders. I've re-shaped the cowl slightly with heat, and filled in gaps, plus added 1/4" to the back of the bottom cowl that I cut too short during the fitting process. In the end, it all again looks original.

Thats a good point. That will have to be the direction that I take. I wanted to get a lot more progress this weekend but I have been running in circles on this top cowel all day.

Thanks again

robertahegy · #9 05-30-2005, 03:48 PM

You will find that in order to get your cowl to fit and look nice, you will need to do a lot of fitting, filling, filing, glassing, shaping, and swearing to get it the way you want it.

The canopy, cowl, and engine baffles will be the most tedious parts of the building process. Hang in there. Patience really pays off here.

Roberta

DadOf3 · #10 05-30-2005, 08:50 PM

Quote:

Originally Posted by robertahegy

You will find that in order to get your cowl to fit and look nice, you will need to do a lot of fitting, filling, filing, glassing, shaping, and swearing to get it the way you want it.

The canopy, cowl, and engine baffles will be the most tedious parts of the building process. Hang in there. Patience really pays off here.

Roberta

Thanks,
I got the cowling about 90% done today. I will neet to glass and even up a few areas, but that whole engine being out of allignment with the center line confused me for a while. basically wasted a day. Any way, its done now.

Thanks to all