Weight and balance Hippert's plane

[Jeff Brooks]

Buck,
Have you done any taxi tests yet?

[buck toenges]

Here is the counter weight we added to the front of the fuselage. It weighs 140lbs. The cg is now 66" from front of prop or 4" behind the leading edge of bottom wing. We will try this in our early trials and see how everything works out. The weight is support from the engine bearers. It consist of 2 hangers that are bolted to the engine bearers and "triangulated" to the bottom supports. The main weight of 120lbs is then bolted onto these hangers. The weight is supported from the main engine bearers!

Right now after all this I will say I like the way Pavel is using his GQ 70. His engine only sticks out an additional 8", weighs in about 650lbs, throws a prop of 103" and has a lot more torque then the 30. That being said I will try our current set up and see how it works.

By the way I did weigh the tail feathers today since I had nothing better to do and here is what I got.
Horizontal Stabilizer without the two support struts weigh 34lbs.
Rudder and fin weigh 10.4lbs.

Thanks,
Buck

[gipsymoth236k]

Hi Buck,

You probably already have this information, but here it is for others to see:

Your horizontal stab wt is 34# vs original @ 17.6# (French Report) or 12# 6oz. (English Report).

Your combined rudder and fin wt is 10.4# vs original @ 6.6# (French Report) or 6# 9oz (English Report).

There are a weight differences here, as your tail assemblies are quite heavy compared to the originals. Do you have correct information for the original design of the various tubing wall thickness? I have all these, if interested.

Regards,
Gary Sewall

[buck toenges]

Gary,
I didn't realize the weight difference between the horizontal stabilizer of my plane and the original. When I weighed them I thought they were pretty light. I knew that the original were light but not that much lighter. Gary were those weights with coverings?
I should have weigh each major component so as to compare. Jeff, Pavel, and willem do you have any figures from your planes? I'll write to the fellows in N.Z. and see if they have that information available.

Buck

[gipsymoth236k]

Buck,

My detailed research material for all these assemblies can be found in the excellent Fokker D.VII drawings that Jim Kiger of REPLICRAFT provides. I supplied Jim my research material and he drafted it into his plans:

About Replicraft

For those who are interested, these drawings are VITAL to Fokker D.VII structual research, and especially to replica builders. EVERY detail is covered in these amazing drawings.

I can list here on the Forum all original tubing sizes and wall thickness in the D.VII's tail components, if desired.

Regards,
Gary Sewall

[Jeff Brooks]

Buck,
does your weight for the horizontal stab include the elevator?

[gipsymoth236k]

All the English report weight figures are WITHOUT fabric. It is unknown if the French report is with or without fabric.

Elevators - French Report @ 9.9#, English Report @ 11# 2oz.

Regards,
Gary Sewall

[Jeff Brooks]

Gary & Buck,
My stab came out at 17# and the elevator at 11# with out fabric. so you figure together ... 28#, adding fabric could be another 6 more pounds. so Bucks figures could be the two pieces together.

[buck toenges]

Jeff,
Horizontal stabilizer and elevator combined = 34 lbs covered. This does not include the 2 support struts under the stabilizer.

[zffltd]

Originally Posted by buck toenges

Gary,
I didn't realize the weight difference between the horizontal stabilizer of my plane and the original. When I weighed them I thought they were pretty light. I knew that the original were light but not that much lighter. Gary were those weights with coverings?
I should have weigh each major component so as to compare. Jeff, Pavel, and willem do you have any figures from your planes? I'll write to the fellows in N.Z. and see if they have that information available.

Buck

I think I post my weights on my tread.

Pavel