Important notice
Please remember that people from all over the world read and post on this forum, and that every country has its own rules, regulations and standards. This forum is based in the USA and so much of the information posted here is for the benefit of people who operate aircraft in the experimental/exhibition or experimental/racing categories. Advice given on this forum may be region specific. A person from Europe, for example, may make suggestions perfectly appropriate for a U.S reader, although not acceptable in his home country!

Please take this into account and carefully consult the authorities, standards and approved documentation where you fly.
Fournier Forums Upload picture | User Cp  |  Register  |  Members  |  Search  |  Help
    |- Fournier Aircraft > Maintenance Post New Topic   Post A Reply
Really re-covering Wagon printer friendly version
next newest post | next oldest post
Author Messages
Bob Grimstead
Captain

Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2027

Click here to see the profile for Bob Grimstead Visit http://www.redhawksduo.co.uk Send email to Bob Grimstead Send private message to Bob Grimstead Find more posts by Bob Grimstead Edit or delete this message Reply w/Quote
Posted Thursday, November 6, 2014 @ 08:43 PM  

Hi Guys,

One year, one month, one week and a lot of money later, the Trustee in Bankruptcy allowed me to collect my British (formerly red) Fournier RF4D from the workshop of Tony Hoskins's South East Aircraft Services.

I am very pleased to say that, although the airframe has been stripped down to its last nut and bolt (completely against my wishes, of course) it seems that nearly everything is there. I can't find the long wheel retraction lever or any of my several tailwheels, all the materials I bought are missing, and I'm sure there will be other things found lacking, but I actually feel optimistic that, given time, I shall be able to get it airborne again.

The big issue is the skin and possibly other structure that has been removed in the lower last fuselage bay, but I think I may have a solution to that. My inspector is currently researching my suggestion, to see whether it is both feasible and within my limited abilities.
What has been done seems to have been done well, although I was never consulted about it before work started, and didn't want it done. However, it's pointless dwelling on the past. I must go forward from here.

Since all my money has gone and I'm up to my overdraft limit, I shall be selling my Land Rover to buy the neccessary covering materials.

Because I have to work in a windy, open, damp hangar in November, and I have neither spraying booth, compressor, clothing nor the required skills, I shall be using the Oratex system which is not only considerably lighter than the Polyfiber I had originally wanted, but is ready coloured, and seems within my unskilled ability to apply. Very fortunately, for a few weeks anyway, I have the services of Pat Willis to help me.

Here's their web site: http://www.betteraircraftfabric.com

I would be very interested and grateful to hear from anybody who has first-hand experience of working with Oratex.

Yours, Bob

--------------------
Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV

Roger.Camp
Sergeant

Gender: Male
Location: Ireland
Registered: Nov 2013
Status: Offline
Posts: 35

Click here to see the profile for Roger.Camp Send email to Roger.Camp Send private message to Roger.Camp Find more posts by Roger.Camp Edit or delete this message Reply w/Quote
Posted Thursday, November 13, 2014 @ 04:02 AM    YIM

Hi Bob, i have been following on FB. Good to see Wagon moving back "home" again where she belongs. In years gone by I used oratex on my Model AC which generally had a wingspan of 2.5 - 3 m. It is easy to use, get a couple of Model AC books from traplet publishing or accost the local model shop proprieter these guys know what they are talking about. Its like ironing your shirts, maybe your domestic engineer (Financal Advisor in my case) can give you some tips on the correct T and Ps and most of all the V speeds aproaching some of the compound curves when ironing on the covering. I always used a sanding sealer such as Clou to seal the pores and had no probs ironing on the Solartex or oratex. Some areas need a hot air gun but generally the good old iron is best.

Bob for your info:
https://www.oracover.de/downloads2/STC/ADxC-51-001%20AMM%20Edition%203.2%20Oratex%20Application%20Manual%20%20Airplane%20Maintenance%20Manual%20Supplement%2018-08-14.pdf

This is the manual in English for application and maintenance of oratex.

Rog

[Edit by Roger.Camp on Thursday, November 13, 2014 @ 04:26 AM]

--------------------
It takes 1.460 bolts to build an aircraft and 1 nut to spread it over the landscape

Bob Grimstead
Captain

Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2027

Click here to see the profile for Bob Grimstead Visit http://www.redhawksduo.co.uk Send email to Bob Grimstead Send private message to Bob Grimstead Find more posts by Bob Grimstead Edit or delete this message Reply w/Quote
Posted Thursday, November 13, 2014 @ 04:26 AM  

Hi Roger,

Thank you very much for that advice.
I've already read their manual and a Kitplanes article, but there's no substitute for hands-on experience, so next week I shall be going up to UK Oratex importers The Light Aircraft Company with Pat and John for some practical instruction.

I do understand that Oratex doesn't shrink as much as Ceconite, Polyfiber or Diatex, so compound curves and corners are more difficult.

The 'good' thing is that I'm not interested in having a superb finish. All I want is all I wanted more than a year ago: a flying aeroplane that doesn't look as bad as it did when I bought it.

I'll keep everybody updated here.

Yours, Bob

--------------------
Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV

Donald
Command Sergeant Major

Gender: Male
Location: Scotland
Registered: Jan 2007
Status: Offline
Posts: 489

Click here to see the profile for Donald Send email to Donald Send private message to Donald Find more posts by Donald Edit or delete this message Reply w/Quote
Posted Friday, November 14, 2014 @ 02:20 AM  

Hi Bob,

Assuming AWGN is on a Permit to Fly is Oratex acceptable to the LAA here in Britain? I searched their forum but had only a couple of 'hits' and these were questions rather than answers or guidance. It'll be interesting to hear how this progresses.

Bob Grimstead
Captain

Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2027

Click here to see the profile for Bob Grimstead Visit http://www.redhawksduo.co.uk Send email to Bob Grimstead Send private message to Bob Grimstead Find more posts by Bob Grimstead Edit or delete this message Reply w/Quote
Posted Friday, November 14, 2014 @ 07:29 AM  

Hi Donald,

Yes, WGN's on an EASA Permit to Fly, administered by the LAA.

Several British aircraft are already covered with Oratex, including a big Robin and a Pitts Special.

I've notified Francis Donaldson, and the Oratex company is currently reviewing my paperwork submission.
Their main concern seems to be the area of unsupported fabric. There is apparently a maximum, and the second bay out from the wing root has the greatest unsupported area. I've sent them the drawings, so they can do the calculations, but since all their technical info suggests that Oratex is stronger in warp, weft, tear resistance, burst strength etc than either Ceconite or Polyfiber, and seeing that WGN was atripped of thirty year-old Ceconite and HDO's covered in twenty-plus year-old Polyfiber, I can't see how there could possibly be a problem (famous last words!)

Meanwhile, I have a question for you all....

The only available Fournier drawing dealing with fabric covering that I can find is 3-00-03.
This is of course an RF3 drawing, but is included in the RF4D package, so presumably, since their overall shapes are near identical, applies to the RF4D equally.
This shows no indication of fabric reinforcing tapes.
Indeed, HDO, my blue Australian Fournier has no reinforcing tapes.

I know how engineers in general, and Francis in particular, love to cover their asses by specifying unnecessary additional requirements, so to forestall this, is there any other RF4D owner out there whose wing does NOT have reinforcing tapes?
Obviously, nobody has rib stitching or lacing either, do they?

Thanks in advance for any info.

Yours, Bob

--------------------
Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV

SteveBeaver
General

Gender: Male
Location: Columbus, Ohio - USA
Registered: Jan 2007
Status: Offline
Posts: 454

Click here to see the profile for SteveBeaver Visit http://www.bucker.info Send email to SteveBeaver Send private message to SteveBeaver Find more posts by SteveBeaver Edit or delete this message Reply w/Quote
Posted Friday, November 14, 2014 @ 11:23 AM    YIM

Bob,

My aircraft does not have reinforcing tapes over the ribs. My interpretation is that that chord-wise reinforcing tape over the ribs is installed to cover and smooth the stitching or lacing. Since the Fournier has no lacing, it requires no tapes. I know that Joe Foley's RF4, which still has its original factory covering does not have rib tapes either.

I notice that the plywood capstrips that cover the ribs have chamfered edges. I assume this is to mitigate any possible abrasion between the fabric and the cap strip.

Steve

Bob Grimstead
Captain

Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2027

Click here to see the profile for Bob Grimstead Visit http://www.redhawksduo.co.uk Send email to Bob Grimstead Send private message to Bob Grimstead Find more posts by Bob Grimstead Edit or delete this message Reply w/Quote
Posted Friday, November 14, 2014 @ 02:20 PM  

Thank you very much Steve,

That's exactly what I had hoped to hear.

And you're quite right, the rib cap-strips are chamfered.

Thank you very much for that info Steve.

Anybody else?

Yours, Bob

--------------------
Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV

Bob Grimstead
Captain

Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2027

Click here to see the profile for Bob Grimstead Visit http://www.redhawksduo.co.uk Send email to Bob Grimstead Send private message to Bob Grimstead Find more posts by Bob Grimstead Edit or delete this message Reply w/Quote
Posted Sunday, November 16, 2014 @ 04:27 PM  

Matthew gave me the sawn-up remains of F-BMKC, third pre-production RF4.
Although the actual tail skin section that 'WGN needs has already been sawn out, the section immediately ahead of it is still there.
It is made from the correct thickness of plywood, with its grain correctly aligned. It is curved (although not quite enough) and it is virtually the same age.

So Pat cut out that section.

--------------------
Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV

Bob Grimstead
Captain

Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2027

Click here to see the profile for Bob Grimstead Visit http://www.redhawksduo.co.uk Send email to Bob Grimstead Send private message to Bob Grimstead Find more posts by Bob Grimstead Edit or delete this message Reply w/Quote
Posted Sunday, November 16, 2014 @ 04:39 PM  

Then I carefully chiselled away the spruce & ply internal structure.

Next, I used sanding wheels and the Dremel to even more carefully grind away the remaining internal structure.
Obviously this liberated a huge amount of dust, including a good proportion of resorcinol glue dust, so face-mask and gloves were essential.

The Betty Crocker Dark Fudge Chocolate Frosting container is full of the stuff.

[Edit by Bob Grimstead on Sunday, November 16, 2014 @ 04:50 PM]

--------------------
Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV

Bob Grimstead
Captain

Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2027

Click here to see the profile for Bob Grimstead Visit http://www.redhawksduo.co.uk Send email to Bob Grimstead Send private message to Bob Grimstead Find more posts by Bob Grimstead Edit or delete this message Reply w/Quote
Posted Wednesday, November 19, 2014 @ 08:23 AM  

Having cleaned out the interior of this old tail skin, I needed to strip off the exterior fabric.

I didn't like the idea of using paint-stripper because I couldn't be certain of washing off all the residue, and the consensus of opinion on these pages was to use a heat gun. Unfortunately I don't have a heat gun in Britain, so, shhh, don't tell Karen, I used her hair drier.
It doesn't get as hot as a heat gun, so it took longer than I hoped. Also, after an hour it stopped working (shhh again) so I changed to another one from our guest room.

[Edit by Bob Grimstead on Wednesday, November 19, 2014 @ 07:42 PM]

--------------------
Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV

Bob Grimstead
Captain

Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2027

Click here to see the profile for Bob Grimstead Visit http://www.redhawksduo.co.uk Send email to Bob Grimstead Send private message to Bob Grimstead Find more posts by Bob Grimstead Edit or delete this message Reply w/Quote
Posted Wednesday, November 19, 2014 @ 07:55 PM  

So now it's stripped, but only half as curved as it needs to be. Talking with Paul Hendry-Smith of The Light Aeroplane Company, he said they make their Sherwood Rangers' D-section leading edges by soaking the ply in hot water overnight, and then leaving them in an appropriately curved jig for the day to dry out into the correct shape.

So I ran half a bath of hot water, put a length of four-inch aluminum tubing inside the skin, wrapped it around with elastic bands, and left it in the bath overnight.

In the morning it was more curved, but not yet perfect, so I tightened the elastic bands and changed the water, adding some extra boiling water from kettle & saucepans.

Four hours later it was almost the right shape, so I put it in place, held in position with bungee straps and one G cramp to make the sides parallel.

[Edit by Bob Grimstead on Thursday, November 20, 2014 @ 07:36 PM]

--------------------
Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV

Roger.Camp
Sergeant

Gender: Male
Location: Ireland
Registered: Nov 2013
Status: Offline
Posts: 35

Click here to see the profile for Roger.Camp Send email to Roger.Camp Send private message to Roger.Camp Find more posts by Roger.Camp Edit or delete this message Reply w/Quote
Posted Thursday, November 20, 2014 @ 07:35 AM    YIM

In the words of Hannibal Smith "dont you just love it when a plan comes together", Good news Bob. Basic cabinetmaker skills is all it is. Nice to see some progress.

Rog

--------------------
It takes 1.460 bolts to build an aircraft and 1 nut to spread it over the landscape

Bob Grimstead
Captain

Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2027

Click here to see the profile for Bob Grimstead Visit http://www.redhawksduo.co.uk Send email to Bob Grimstead Send private message to Bob Grimstead Find more posts by Bob Grimstead Edit or delete this message Reply w/Quote
Posted Wednesday, November 26, 2014 @ 09:23 AM  

Meanwhile, in the damp & draughty hangar, cleaning off the wing all the half-inch of old Super Seam Cement with nitrile gloves, gallons of MEK and tons of elbow-grease.

--------------------
Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV

SteveBeaver
General

Gender: Male
Location: Columbus, Ohio - USA
Registered: Jan 2007
Status: Offline
Posts: 454

Click here to see the profile for SteveBeaver Visit http://www.bucker.info Send email to SteveBeaver Send private message to SteveBeaver Find more posts by SteveBeaver Edit or delete this message Reply w/Quote
Posted Wednesday, November 26, 2014 @ 09:31 AM    YIM

That's very attractive fabric you've got there Bob. Is that a new PolyFiber product?

Steve

Bob Grimstead
Captain

Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2027

Click here to see the profile for Bob Grimstead Visit http://www.redhawksduo.co.uk Send email to Bob Grimstead Send private message to Bob Grimstead Find more posts by Bob Grimstead Edit or delete this message Reply w/Quote
Posted Wednesday, November 26, 2014 @ 06:34 PM  

That's grea!

I snorted my wine!

Old bed sheets (previous marriage) make great rags.

Thanks Steve. It's been a bit lonely and cheerless, but you've cheered me right up.

Varnish tomorrow I hope (or the next day).

Yours, Bob

--------------------
Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV

Jorgen
Captain

Gender: Male
Location: Lund, Sweden
Registered: Apr 2007
Status: Offline
Posts: 833

Click here to see the profile for Jorgen Send email to Jorgen Send private message to Jorgen Find more posts by Jorgen Edit or delete this message Reply w/Quote
Posted Sunday, November 30, 2014 @ 04:04 PM  

Bob,
keep yer faith up, remember the Sun always eventually shines down on a true Fournieteer.

That is if he keeps the blue side up of course;-)

May the 4s be with you/ Jörgen

Bob Grimstead
Captain

Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2027

Click here to see the profile for Bob Grimstead Visit http://www.redhawksduo.co.uk Send email to Bob Grimstead Send private message to Bob Grimstead Find more posts by Bob Grimstead Edit or delete this message Reply w/Quote
Posted Monday, December 1, 2014 @ 08:12 PM  

Thanks Steve & Jorgen,

Progress always seems slower than hoped-for, but at the moment it is at least happening, albeit slowly.

I got fed up paddlng about in an inch of water with the wind whistling through my wind-tunnel hangar, clothes and body, so I moved the wing, trailer and all into one of the big ex-RAF hangars on the north side (near the Top Gear studio). It's expensive, and it's still very cold, but it's dry, there are transparent roof panels and high-power lights, electricity, toilets and a café within walking distance.
I've got all the old Super Seam Cement off the upper surface with lashings of MEK, made a couple of small repairs where there's been storage damage, tried to push out four areas of convex oil-canned ply, and leached out some oil staining on the left leading-edge.
I've also made a rudimentary stand on which to turn over the wing to clean off its underside. That's the odd structure you can see protruding above the centre-section.

All being well, it will go upside-down tomorrow.

Yours, Bob

--------------------
Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV

Bob Grimstead
Captain

Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2027

Click here to see the profile for Bob Grimstead Visit http://www.redhawksduo.co.uk Send email to Bob Grimstead Send private message to Bob Grimstead Find more posts by Bob Grimstead Edit or delete this message Reply w/Quote
Posted Tuesday, December 2, 2014 @ 10:16 AM  

The poor thing hasn't flown for more than two years, but at least now the wing is upside-down again.

Earlier we were talking about LAA approval of Oratex 600.
I had presumed that, since Fourniers meet all Oratex's specs, I would merely have to buy the stuff and use it, as I would with Diatex, Polyfiber or Ceconite. However, the wording of Francis Donaldson's reply to my e-mail suggests I needed and have now received his approval (after just 12 days). Presumably, once mine is successfully flying (this time next year?) Oratex will be OK for any LAA Fournier.

Finally, just for fun, a hangar selfie.

Yours, Bob

--------------------
Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV

Donald
Command Sergeant Major

Gender: Male
Location: Scotland
Registered: Jan 2007
Status: Offline
Posts: 489

Click here to see the profile for Donald Send email to Donald Send private message to Donald Find more posts by Donald Edit or delete this message Reply w/Quote
Posted Tuesday, December 2, 2014 @ 04:56 PM  

That looks a lot more hospitable than the Polytunnel, Bob, though from your attire it's evidently not warm. Still, dry and bright is good.

Is the LAA warm or cool to the idea of Oratex? I know Francis has the rep of being rather fastidious and conservative (with a small c) so are you trailblazing the material's use in the UK, or just the material's use on a Fournier?

Bob Grimstead
Captain

Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2027

Click here to see the profile for Bob Grimstead Visit http://www.redhawksduo.co.uk Send email to Bob Grimstead Send private message to Bob Grimstead Find more posts by Bob Grimstead Edit or delete this message Reply w/Quote
Posted Tuesday, December 2, 2014 @ 05:11 PM  

Hi Donald,

Notice red jumper & hat to match nose!

Oratex has been used on a dozen or more British aeroplanes, including a Pitts & a Robin.
I already knew Francis was enthusiastic from Light Aircraft magazine, but for some reason he wanted to approve its use in this particular application.

I have a strong feeling that in ten years everybody will be using it... no nasty MEK, spray booth, respirator, noisy compressor etc, just splosh-on water-based adhesive.

Time will tell.

I shall certainly be glad to get that MEK smell out of my nostrils.
Just one more day, I hope.

Yours, Bob

--------------------
Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV

Bob Grimstead
Captain

Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2027

Click here to see the profile for Bob Grimstead Visit http://www.redhawksduo.co.uk Send email to Bob Grimstead Send private message to Bob Grimstead Find more posts by Bob Grimstead Edit or delete this message Reply w/Quote
Posted Sunday, December 7, 2014 @ 06:27 AM  

I think I've pretty much finished using MEK to clean off the old Super Seam Cement.
It's interesting that there was so much of it plastered all over the wing. I guess it would normally come off with the fabric, but Tony Hoskins said "The fabric just fell off". I can only presume that the cement wasn't properly sucked up through the fabric by MEK in the first place.

AIs and AEs might throw up their hands in horror, and that certainly isn't the way it should have been done, but it has lasted since 1982 (31 years) and I've flown more than 300 hours of vigorous aerobatics in it (with exceedences up to +7.5g) without any sign of the fabric coming off the wing.
This just goes to show how very cautious and conservative we all are in these things.

One benefit... The MEK may make me feel light-headed, and I know it's bad for you, but the used rags make great firelighters.
This is just fifteen minutes after throwing one match from a safe distance.

--------------------
Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV

Bob Grimstead
Captain

Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2027

Click here to see the profile for Bob Grimstead Visit http://www.redhawksduo.co.uk Send email to Bob Grimstead Send private message to Bob Grimstead Find more posts by Bob Grimstead Edit or delete this message Reply w/Quote
Posted Sunday, December 7, 2014 @ 07:11 PM  

I've just come across something surprising and rather shocking.

In order to fit the new outrigger legs, quite correctly, they cut holes intomthe underside of each wing's structural D-box. These holes are approximately 4in by 2.5in -- about the size of an iPhone. After this work, they made up a pair of plates to glue over these holes, but for irrelevant reasons they never actually glued them in place.

On Friday I was about to varnish the insides of these plates prior to gluing them in myself, when their significantly lighter colour attracted my attention. Then, as I studied them more closely, a couple more issues became apparent. Take a look yourself.

The wing's leading-edge D-box is of course vital torsion-resisting structure, and these holes were cut immediately outboard of rib No 9. This is a much stronger rib than the others, and coincides with the outer end of the spoiler torque tube, the inboard end of the aileron cut-out, and it's where the outrigger leg attaches. From memory, it was at this rib that the wing broke when under structural testing in Paris, so it is important these plates and their gluing into position are at least as strong as the original structure.

The plywood skin here is 2mm thick, with the outer grains running spanwise. The patches are also of 2mm ply with the outer grains running spanwise, but there the resemblance ceases.

The wing's ply is clearly made up of five laminates and glued with resorcinol, whereas the plates have only three plies and are not resorcinol glued. Model aeroplanes were being built in the workshop at the time of this work, and I now strongly suspect that this material is not aircraft quality plywood at all, but model aeroplane ply.

Furthermore, AC 43.13-1B stipulates scarfs of at least 1:12 in structural components. If the ply is 2mm thick, then these scarfs should be at least 24mm (one inch) wide.

Measurement with a vernier caliper showed them to be much narrower than this. They ranged between 1:6.5 and 1:3.5, meaning that the most tapered scarf was only half the taper it should have been, and the worst was only a quarter.

I have no idea how much weaker this would have made my wings, but I am now really glad that the patches had not already been glued into place. If they had been, I would have had no clue that a sub-standard repair had taken place.

The plates should be the size of that pencilled rectangle, and the scarf chamfers should go out all the way to those lines.

So, instead, I've spent the evening converting the edges of a couple of larger pieces of proper aircraft quality, five-laminate plywood into very fine dust with a block of wood and some 240 grade glasspaper.

It was time-consuming, but strangely satisfying, and very reassuring to know things have now been done properly.

Yours, Bob

[Edit by Bob Grimstead on Thursday, December 11, 2014 @ 06:17 PM]

SteveBeaver
General

Gender: Male
Location: Columbus, Ohio - USA
Registered: Jan 2007
Status: Offline
Posts: 454

Click here to see the profile for SteveBeaver Visit http://www.bucker.info Send email to SteveBeaver Send private message to SteveBeaver Find more posts by SteveBeaver Edit or delete this message Reply w/Quote
Posted Sunday, December 7, 2014 @ 09:12 PM    YIM

That's an awfully big hole! Mine are more like slots about 4" x 3/8"

Steve

Donald
Command Sergeant Major

Gender: Male
Location: Scotland
Registered: Jan 2007
Status: Offline
Posts: 489

Click here to see the profile for Donald Send email to Donald Send private message to Donald Find more posts by Donald Edit or delete this message Reply w/Quote
Posted Monday, December 8, 2014 @ 02:07 AM  

Good spot, Bob. Makes you wonder who signed off on that work.
Roger.Camp
Sergeant

Gender: Male
Location: Ireland
Registered: Nov 2013
Status: Offline
Posts: 35

Click here to see the profile for Roger.Camp Send email to Roger.Camp Send private message to Roger.Camp Find more posts by Roger.Camp Edit or delete this message Reply w/Quote
Posted Tuesday, December 9, 2014 @ 06:27 AM    YIM

Hi Bob, having built and are still building large scale models, that does look familiarly like obechi ply, which for scale 1.1 models has next to no strength at all. Like my gran would say"if you want it doing properly then do it yourself". Well done you for spotting this. Could have been somewhat emb-arseing.

Rog

--------------------
It takes 1.460 bolts to build an aircraft and 1 nut to spread it over the landscape

Bob Grimstead
Captain

Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2027

Click here to see the profile for Bob Grimstead Visit http://www.redhawksduo.co.uk Send email to Bob Grimstead Send private message to Bob Grimstead Find more posts by Bob Grimstead Edit or delete this message Reply w/Quote
Posted Tuesday, December 9, 2014 @ 09:26 AM  

I've just taken those ply plates to the local model shop, to ask if they were indeed obechi ply.

"Oh no, they're not as strong as that," said the guy. "They're what we call 'light ply'. See that central layer? That's balsa wood."

I'm not often rendered speechless, but I was!

Draw your own conclusions.

Yours, Bob

--------------------
Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV

Bob Grimstead
Captain

Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2027

Click here to see the profile for Bob Grimstead Visit http://www.redhawksduo.co.uk Send email to Bob Grimstead Send private message to Bob Grimstead Find more posts by Bob Grimstead Edit or delete this message Reply w/Quote
Posted Tuesday, December 9, 2014 @ 08:16 PM  

At last I've actually put on some Oratex fabric!
I decided to start with the most difficult & complicated area: the aileron cut-outs.
And I decided to use the give-away sheet of khaki-coloured fabric Paul gave me to practise on.
You can't see this area when the aileron's in position, so the colour didn't matter.
Ditto if my results looked ugly.
And the stuff's so darned pricey I figured I could always remove & discard the khaki fabric if it really went badly, and still have enough white to cover the whole airframe.
In reality it went on pretty well, I thought.
All the info on how to do this is in their manual, available free in a pdf on their web site.

First you strip off all the old adhesive -- three weeks work in my case.
Then you roughen the surface with 120 grit glasspaper -- ten minutes.
Then you varnish it once with very slghtly thinned exterior varnish (in this case Ronseal Yacht Varnsh) -- half an hour.
Go away or do other things for two days while that dries.
Sand lightly with 240 grit paper -- 10 mins.
Apply second coat -- 20 mins.
Go away two more days (ambient temps +1 to +7C).
Roughen the varnished surface with a maroon/red (fine) Scotchbrite pad -- ten mins.
Paint on the ready mixed, water-based adhesive with a foam 'brush' -- twenty mins (no mess, absolutely no smell) but try not to form any tiny bubbles.

Also paint a thin, even layer of the ready mixed, water-based adhesive on to the back of the fabric with a foam 'brush' -- twenty mins.
The fabric is remarkably fine, thin and light -- lovely.
Allow both to dry. In very low ambient temperatures drying can be slow. Heat doesn't help, but airflow does, so a fan, or a heat-gun or fan-heater set to 'cold' or 'cool' greatly assists. This took half an hour with a cool (50C) heat-gun in an ambient temp of about +4 or 5C.
Holding the fabric carefully in place, and using a small modeller's iron with accurate temp control set to 100C press down in a few spots to tack it in place.
Once satisfied everything is square, true and wrinkle-free, go over it all with the iron, working carefully from one side to the other to get out any bubbles, ensuring the iron is over every bit of the fabric for ten seconds and pressing down reasonably firmly (they quote seven pounds of pressure) to pop all the little hardener microballoons in the adhesive.
That took about forty minutes for the first piece, less than half an hour for the second.

Trim off the surplus -- thirty seconds.

No painting of any sort required. That's it.

Go home and drink copious volumes of good Australian Shiraz to celebrate a job well done!

Yours, Bob

[Edit by Bob Grimstead on Tuesday, December 9, 2014 @ 08:18 PM]

[Edit by Bob Grimstead on Wednesday, December 10, 2014 @ 09:32 AM]

--------------------
Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV

Bob Grimstead
Captain

Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2027

Click here to see the profile for Bob Grimstead Visit http://www.redhawksduo.co.uk Send email to Bob Grimstead Send private message to Bob Grimstead Find more posts by Bob Grimstead Edit or delete this message Reply w/Quote
Posted Tuesday, December 9, 2014 @ 08:35 PM  

Yes Steve, they're needlessly big holes (unfortunately I wasn't present when they were cut) but interestingly, they're not the biggest patches in this wing. Remember, the airplane's 46 years old and flown 3,600 hours, and I am its first private owner.

Previously it was operated by a flying school and a sucession of syndicates, and it has suffered at least one major accident in which the whole fuselage had to be replaced.
I count a total of fourteen holes in its lower wing surface, the biggest of which is 24ins by 18 ins, although eight are 2.5in discs in each bay of the right wing, where presumably a borescope has been inserted.

These repairs are obviously adequate in the light of the fairly vigorous aerobatics I have flown over the years, although the wing's surface is far from even and there must be a weight penalty.

I hope my patches ate now similarly adequate!

Yours, Bob

--------------------
Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV

Bob Grimstead
Captain

Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2027

Click here to see the profile for Bob Grimstead Visit http://www.redhawksduo.co.uk Send email to Bob Grimstead Send private message to Bob Grimstead Find more posts by Bob Grimstead Edit or delete this message Reply w/Quote
Posted Thursday, December 11, 2014 @ 06:13 PM  

I didn't think my first attempt at glueing in a ply patch went too badly, considering I'm a complete amateur virgin novice at this stuff.


...and here's that first finished bit of fabric in the daylight. Yes, it's an odd khaki colour, but it's adhered pretty well despite being on a multi-faceted and uneven concave surface, so I don't have to take it off again; and it won't show behind the aileron. I don't want to sound over-confident, but the process was every bit as easy as Paul H-S said it would be.

I suspect the next most difficult bit will be stretching it around the wing tips, but if I muck that up it will be covered by the smoke pods, so I'm going to forge ahead anyway.

As ever, preparation is the most important thing. I've cleaned, sanded & varnished (once) all the wing but the centre section, where I'm still trying to leach out the last of the oil stains. Second coat tomorrow and I'll let it dry over the weekend.

Yours, Bob

--------------------
Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV

Markku
Master Sergeant

Gender: Male
Location: Kouvola, Finland, EFWB
Registered: Oct 2006
Status: Offline
Posts: 167

Click here to see the profile for Markku Visit http://picasaweb.google.com/markkuk04 Send email to Markku Send private message to Markku Find more posts by Markku Edit or delete this message Reply w/Quote
Posted Friday, December 12, 2014 @ 06:07 AM  

Hi Bob
Looks good, I can almost feel the smell....
I was wondering how you managed to glue the piece with resorsinol, normally it needs a lot of pressure, and it's not easy in that point when you cannot support the glue joint from backside
Markku
Pages 1 of 2 Pages: 1, 2
Post New Topic   Post A Reply Jump to:
Contact Us | cfiamerica.com | Privacy Policy All times are GMT -4 Hours.
Welcome to The Fournier Forum, Guest!  
Login
Username :
Password :
In order to fully utilize the abilities of this board, you are required to register as a member. Registration is free, and allows you to do lots of things including turning on or off certain features of this board. Register now!
Forum Rules & Description
Who Can Read The Forum? Any registered user or guest
Who Can Post New Topics? Any registered user
Who Can Post Replies? Any registered user
Who Can Edit Posts? Any original author
Tips for maintaining Fournier Motor gliders
Currently Active Users: 115
There are currently 0 members and 115 guests on the boards. | Most users ever online was 822 on 08-01-2020 10:15 PM
Search This Forum
Search Keywords: Search From:
Powered by CuteCast v2.0 BETA 2
Copyright © 2001-2003 ArtsCore Studios