Why were longerons fabric wrapped?

abufletcher · 24 March 2005, 08:57 AM

What was the purpose of wrapping longerons? After seening Achim's wrappings on his DVII's tubing I guess I had always assumed this was to avoid wear on the fabric covering.

But in the Pflaz DIII datafile (#107) on item in the evaluation report reads:

"The fuselage longerons must be of ash to the pilot['s cockpit and wrapped."

Why would a plane with the Pfalz's wooden skin need to have wrapped longerons?

AAC Cadet Leader · 24 March 2005, 09:03 AM

It was the latest spa(r) treatment.

Sorry, couldn't resist. I'll go back to Off Topic now.

franzkait · 24 March 2005, 10:24 AM

why are all the fokker D7 spars wrapped ? wrappe some wood with linnen and break it.

StephenLawson · 24 March 2005, 11:12 AM

Quote:

Originally Posted by abufletcher

What was the purpose of wrapping longerons? After seening Achim's wrappings on his DVII's tubing I guess I had always assumed this was to avoid wear on the fabric covering.

But in the Pflaz DIII datafile (#107) on item in the evaluation report reads:

"The fuselage longerons must be of ash to the pilot['s cockpit and wrapped."

Why would a plane with the Pfalz's wooden skin need to have wrapped longerons?

abufletcher: You are correct. Even the wood sheathed fuselages needed protection from wear against twisting and general vibrations. The fabric acted as a seal and cushoned the skinning against the airframe.

Jim · 24 March 2005, 12:54 PM

Wouldn't the fabric wrapping make the wood much stronger and less prone to cracking?

Dan_San_Abbott · 24 March 2005, 07:09 PM

abufletcher:
Generally it is the splices on the longerons that are wrapped. In some cases the entire longeron is wrapped. The forward longerons are generally ash and the longeron af of the cockpit was spruce or pine. the joint of the two woods had a long splice of 10 to 1 or greater. This joint would be wrapped with a strip of fabric immersed in hot glue and wrapped around the full length of the joint. The French term was marouflage, I think that is the correct spelling. Wrapped longerons provided moisture protection.
Blue skies,
Dan-San

Dan_San_Abbott · 24 March 2005, 07:16 PM

Franzkait:
After the ribs have been assembled on the spars, the top and bottom faces were protected with a piece of cloth glued to the spar face and wrapped over on to the spar plywood faces abot 25 mm. I have a piece off the top wing front spar fron Fok.D.VII 10349/18, it is 5 color printed fabric.
Blue skies,
Dan-San

franzkait · 24 March 2005, 07:28 PM

Dan, not all the spar was wrapped

franzkait · 24 March 2005, 07:35 PM

this was the foto

Dan_San_Abbott · 24 March 2005, 08:11 PM

Franzkait:
Who built the wing, Fokker,Albatros or OAW? The wing that I examined was built by the Fokker Flugzeugwerke from the last production order. At the time it was owned by Jim Matheson and he gave full access to the airframe. This machine is now in Canada.
I made sketches of the spars, and the structure is not what is generally depicted. There is only one spacer between the spars flanges between each strut attachment point. The bottom flange pieces are 7.5 mm thick and are not tapered in thickness, but are stepped, going from 3 plies of 7.5mm to two plies @7.5 mm. The top flange is two plies of 20 mm steps to one ply of 20 mm.
Blue skies,
Dan-San