What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

360 parallel valve & fixed pitch

cgarts1

Well Known Member
So I've got an IO360 L2A hanging on the mount and I'm going with a fixed pitch prop so I'm going to probably be a bit aft on the CG.

So I'm thinking I need to get about 50 lbs FF. I have a few ideas.

The L2A engine has the mounting block on the front for the governor so I thought I might mill a steel block to hang there. Might get 10 lbs. I also figure I can get about 20 more lbs by steel plates on the inner firewall. I'm thinking that's probably close enough. We'll see when it's on the scales.

I'd love to hear some ideas from anyone that has done something similar or has needed to add some weight up front.

Thanks
 
C.G. issues

50 + pounds of dead weight is not the answer. A longer extended Motor mount might be. Move the whole power plant & Prop 2 to 6" forward, it would require modifying the mount or having a custom mount made as well as a custom cowl. Sam James comes to mind. Any change to the plans adds time & expense to the project.
 
By far the most useful 50lbs on the nose of a piston airplane is a CS prop. That’s what I would recommend. Why fixed pitch?
 
CG

I was also concerned about being tail heavy as I wanted to use a composite prop (Whirlwind) and Earth-X battery. My CS prop compared to the standard Hartzell metal was ~30 lbs lighter and my battery another ~10 lbs lighter. I even have the baggage area carpeted along with a yaw damper in the tail. I was looking at possibly putting the ELT up forward somewhere. When I did a W&B it was fine even for acro limits. None of us like to add weight to the nose but aren't worried when our personal airframes gain a few pounds over time. I'm sure however it comes out the CG limits will be adhered to.
 
I was also concerned about being tail heavy as I wanted to use a composite prop (Whirlwind) and Earth-X battery. My CS prop compared to the standard Hartzell metal was ~30 lbs lighter and my battery another ~10 lbs lighter. I even have the baggage area carpeted along with a yaw damper in the tail. I was looking at possibly putting the ELT up forward somewhere. When I did a W&B it was fine even for acro limits. None of us like to add weight to the nose but aren't worried when our personal airframes gain a few pounds over time. I'm sure however it comes out the CG limits will be adhered to.

That is very interesting.

By fine do you mean that a weight and balance computation done with the fuel tanks containing only about five gallons, a 200 lb person in each seat, and 100 lbs in the baggage compartment, the computed CG position is still fwd of the aft limit?
 
CG Calcs using limits

Yes, at 200 lbs each and min fuel and 100 lbs baggage within the utility envelope and without the 100 lbs (I assume no-one flies acro. with baggage) inside the acro. envelope. Checked using my scales and a racing friend of mines scales as I was a little concerned and wanted to double check. One thing of note is the arm for the fuel changes when you go from 5 gals (arm is 82.58 in.) to 50 gals (arm is 81.36 in) but to stay conservative used the arm in the Vans documents for the min fuel arm. I even rotated the airframe 180 degrees to insure the level of the plane did not throw off the measurements. (Its a 14A so doubtful this would happen)
 
Back
Top