Fournier Res­ur­rec­tion Part 3

Fournier Res­ur­rec­tion Part 3: re-cov­er­ing the fuse­lage

Pilot - - CONTENTS - Words and pho­tos: Bob Grim­stead

With the air­craft back to­gether it was time to re-cover the fuse­lage

Ihad wanted to re­place the age­ing fab­ric and shabby paint­work on my wooden Fournier RF4D ‘Wagon’s fuse­lage. I spec­i­fied and col­lected fab­ric and paint of the Poly­fiber sys­tem from Air­craft Cov­er­ings at Hen­stridge be­cause it’s flame­proof, stays flex­i­ble for a very long time, and that’s what I have on my Aus­tralian Fournier and Maule. Now the ma­te­ri­als had dis­ap­peared (see Part 1) so, hav­ing re­paired and pre­pared the Fournier’s air­frame, I re­peated the se­lec­tion process… but this time I would be do­ing the work my­self.

I don’t have a spray gun, com­pres­sor or booth, nor the ap­pro­pri­ate skills for spray painting, and I was con­cerned

about achiev­ing a rea­son­able fin­ish. I had also been pon­der­ing on the necessary elas­tic­ity of the paint coat­ing for the flex­i­ble fab­ric it was go­ing onto; many air­craft re­stor­ers use two-pack polyuretha­ne paints now and I didn’t know if they would be suf­fi­ciently pli­able. Im­por­tantly, most of to­day’s paint sys­tems are clas­si­fied as car­cino­genic, so I would need pro­tec­tive cloth­ing and breath­ing ap­pa­ra­tus.

Then I learned about Ora­tex. I had vaguely heard of it be­fore as ‘a Ger­man air­craft fab­ric us­ing wa­ter-based ad­he­sive’ but, be­ing aware of Ce­conite’s pre­vi­ously un­suc­cess­ful flir­ta­tion with wa­ter-based glues and paints, had dis­missed Ora­tex from my mind. Now I heard some­thing much more at­trac­tive about it: it comes ready-painted!

Paul Hendry-smith of The Light Aero­plane Com­pany (TLAC) was the Bri­tish im­porter of this in­no­va­tive prod­uct. I phoned him for more de­tails. He said a dozen or more Bri­tish air­craft had al­ready been fin­ished with Ora­tex (this was 2015) in­clud­ing a big Robin and a Pitts Spe­cial, which

ought to tes­tify to its strength, and in­sisted this fab­ric would be within my un­skilled abil­ity to ap­ply. He told me Ora­tex was a polyester fab­ric, but its much finer fil­a­ments, threads and weave made it sig­nif­i­cantly lighter than Poly­fiber, Ce­conite or Di­a­tex. He re­ferred to this as ‘nano tech­nol­ogy’. He con­firmed it was ready-painted with seven lay­ers of coat­ings: fab­ric sealant, primer, un­der­coat, three colour coats, and a ure­thane clear top coat, each coat­ing hav­ing a com­bi­na­tion of UV ab­sorbers and block­ers. Ora­tex also sup­plies Ora­colour flex­i­ble paint which con­tains no plas­ti­cis­ers, so an air­craft can have a multi-colour scheme, and self-ad­he­sive trim tapes of many shades (brand names Ora­line for nar­row tape and Oratrim for wider tape).

To­day there are eleven pri­mary fab­ric colour op­tions. Paul did ad­mit that it was ex­pen­sive, but in­sisted that it was no more than the cost of a sim­i­lar area of other polyester fab­rics plus the re­quired half-dozen or more lay­ers of paint. He sent me sam­ples of their white and red fab­rics: In­signia White is a nice bright, ti­ta­nium white, and by chance Fokker Red was pre­cisely the same shade as my Fournier’s ex­ist­ing paint. Paul had cau­tioned me that the fin­ish is not high gloss. The paint is ac­tu­ally quite shiny, but the lay­ers are so thin that the very fine weave shows through im­part­ing a satin-like sheen.

There be­ing no sub­sti­tute for hands-on ex­pe­ri­ence, my friend John Watkins and I drove up to TLAC at Lit­tle Snor­ing for some prac­ti­cal in­struc­tion. Paul him­self gave us a four-hour tu­to­rial in­clud­ing some hands-on work, ex­plain­ing the process step-bystep to re-cover a pre­vi­ously cov­ered air­frame.

The ap­pli­ca­tion of odour­less wa­ter-based ad­he­sive is pretty

sim­ple. Iron­ing the fab­ric in place to ac­ti­vate the glue was just as easy. Shrink­ing it with a heat gun was a quick plea­sure, al­though we learned that Ora­tex doesn’t shrink as much as Ce­conite, Poly­fiber or Di­a­tex, so com­pound curves and cor­ners can be a bit more dif­fi­cult to cover with­out wrin­kles. Paul showed us how to re­move wrin­kles and folds, say­ing, “Never try to shrink a wrin­kle, shrink the area around it. Heat the glue to soften it and then shrink the fab­ric be­side the blem­ish to pull it flat.” He showed us how the fab­ric can be warmed and stretched around the curves of fins and rud­ders, re­count­ing that Ora­tex in­ven­tor Siegfried can cover an en­tire elec­tric light bulb in the stuff with­out it wrin­kling! The good thing was that I’ve never been in­ter­ested in hav­ing a su­perb fin­ish; what I wanted was an aero­plane that didn’t look as scruffy as when I bought it, and back in the air as soon as pos­si­ble.

I soon re­alised the only sig­nif­i­cant dis­ad­van­tage of Ora­tex is the price of ev­ery­thing. To do the job prop­erly Paul in­sisted I needed a Steinel Ger­man dig­i­tal heat gun and a Ja­panese Toko dig­i­tal iron, be­cause of their very ac­cu­rate tem­per­a­ture con­trol. Even the felt pad he rec­om­mended for press­ing the fab­ric down into place after heat­ing the glue was pricey. The paint only comes in one litre cans

Un­der­side of the rud­der pedal at­tach­ment, fully cov­ered

... and the se­cond, pro­tect­ing the rear face

first stage in cov­er­ing the rear edge of the fire­wall...

Com­plex shapes were cov­ered with small sec­tions of Ora­tex

ABOVE: ‘Wagon’s in­verted fuse­lage, with de­tailed for­ward ar­eas now cov­ered

LEFT: fur­ther de­tail – cov­er­ing the un­der­floor re­in­force­ment for the hand starter lever

ABOVE: com­plex shapes un­der the cock­pit floor, cov­ered in Ora­tex

LEFT: stern­post cov­ered in one piece, slit to wrap around the edges

RIGHT: pa­per tem­plates were made for the dif­fi­cult ar­eas

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