I'm building a Pietenpol and would like to use some American 8 foot sheets of ply to minimize the number of scarf joints that have to be made for Fuselage bottom, sides and spar webs.
Can anyone tell me if the MIL-P-6070 standard for ply is acceptable for LAA permit aircraft?
I still don't know if I can get this material at a reasonable price, but if similar to metric prices, I would prefer to have fewer scarfs (and a better end result, in my humble opinion).
Any info would be appreciated.
Thanks,
Mark
Acceptable Plywood Standards
Moderators: John Dean, Moderator
Acceptable Plywood Standards
Mark Bowler
038471
038471
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Chris Martyr
- Posts: 584
- Joined: Wed Dec 15, 2010 10:58 am
- Location: Horsted Keynes Sussex
Re: Acceptable Plywood Standards
Hi Mark,
I'm sure that U.S. spec. Mil-P-6070 would be acceptable for use here, but are you planning to bring it in from across the pond ? As it could be a bit of a palaver.
When I was building my project back in the late 1990's , I bought 1/8" thickness 8ft x 4ft sheets of aircraft mahogany from a company named, British Plywood Manufacturers Ltd. in Enfield N. London, who used to advertise in PF as it was then. I believe they are still there.
The spec. it conformed to was BS2V35. However, I did subsequently obtain marine ply from reputable commercial outlets and found after carrying out some shear tests that there was very little difference, as a matter of fact the commercially available marine ply was slightly stronger !
It is very much a case of 'Caveat Emptor' , the main thing to remember is to specify marine ply and not exterior quality ply, as that will probably have small voids between the laminations.
Don't be blinded by the paper trail and the 'Release Notes and JAA Form 1's that you hear about, it is your Inspector whose say is the most definitive in all this.
A regular contributor on here named Colin Cheese may be able to shed some light on the shear testing part of the operation. I'm sure he's not far away.
Good luck with the AirCamper, I love 'em !
I'm sure that U.S. spec. Mil-P-6070 would be acceptable for use here, but are you planning to bring it in from across the pond ? As it could be a bit of a palaver.
When I was building my project back in the late 1990's , I bought 1/8" thickness 8ft x 4ft sheets of aircraft mahogany from a company named, British Plywood Manufacturers Ltd. in Enfield N. London, who used to advertise in PF as it was then. I believe they are still there.
The spec. it conformed to was BS2V35. However, I did subsequently obtain marine ply from reputable commercial outlets and found after carrying out some shear tests that there was very little difference, as a matter of fact the commercially available marine ply was slightly stronger !
It is very much a case of 'Caveat Emptor' , the main thing to remember is to specify marine ply and not exterior quality ply, as that will probably have small voids between the laminations.
Don't be blinded by the paper trail and the 'Release Notes and JAA Form 1's that you hear about, it is your Inspector whose say is the most definitive in all this.
A regular contributor on here named Colin Cheese may be able to shed some light on the shear testing part of the operation. I'm sure he's not far away.
Good luck with the AirCamper, I love 'em !
022516
Re: Acceptable Plywood Standards
Hi,
I'm here, but possibly not too much help on this.
As far as I know, for birch ply the LAA require either GL1 stamped by the man from Germanisher Lloyd or ply supplied by TLAC tested to a protocol agreed between TLAC and the LAA. As far as I know, these only come in 50" square sheets.
Robbins do I think hold the bigger sheets, but I don't think have 'per sheet' GL approval. You could ask.
Step 1 should be to contact Engineering to check what they require.
If I were you I would just keep things simple, bite the bullet and buy GL1 from Tim Wood or TLAC's product and scarf it. It's really not difficult. Importing bigger sheets will cause you stress! I'm also going to say that we should be grateful that we have people like Tim and Paul H-S taking the trouble to provide a readily available source and patronise them. I haven't bought any since Tim took over Dudley's business, but Dudley used to provide a next-day service to builders and I doubt he ever made much money from it.
The sad thing is that nowadays, the majority of aircraft quality comes from a single factory, Koskisen in Finland and much of the cost is in the approval process. I suspect the GL1 from Tim and the ply from TLAC and Robbins originate from the same stock in Finland.
Sorry I can't be more helpful.
Colin
I'm here, but possibly not too much help on this.
As far as I know, for birch ply the LAA require either GL1 stamped by the man from Germanisher Lloyd or ply supplied by TLAC tested to a protocol agreed between TLAC and the LAA. As far as I know, these only come in 50" square sheets.
Robbins do I think hold the bigger sheets, but I don't think have 'per sheet' GL approval. You could ask.
Step 1 should be to contact Engineering to check what they require.
If I were you I would just keep things simple, bite the bullet and buy GL1 from Tim Wood or TLAC's product and scarf it. It's really not difficult. Importing bigger sheets will cause you stress! I'm also going to say that we should be grateful that we have people like Tim and Paul H-S taking the trouble to provide a readily available source and patronise them. I haven't bought any since Tim took over Dudley's business, but Dudley used to provide a next-day service to builders and I doubt he ever made much money from it.
The sad thing is that nowadays, the majority of aircraft quality comes from a single factory, Koskisen in Finland and much of the cost is in the approval process. I suspect the GL1 from Tim and the ply from TLAC and Robbins originate from the same stock in Finland.
Sorry I can't be more helpful.
Colin
018841
Colin Cheese
Colin Cheese
Re: Acceptable Plywood Standards
Here's a link to the GL1 approval standard:
https://www.aircraftspruce.com/catalog/ ... 0Lloyd.pdf
Regards,
Colin
https://www.aircraftspruce.com/catalog/ ... 0Lloyd.pdf
Regards,
Colin
018841
Colin Cheese
Colin Cheese
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Chris Martyr
- Posts: 584
- Joined: Wed Dec 15, 2010 10:58 am
- Location: Horsted Keynes Sussex
Re: Acceptable Plywood Standards
Colin, thanks for taking the trouble to reply. Hope you didn't feel that you were being coerced to do so. I know from our past communications that like myself , you have a passion for aeroplanes constructed from 'God's own', the first natural composite !
I also found the pdf download quite fascinating , so thanks for that.
A bit embarrassed too, as I hadn't a clue that the GL stood for Germanischer Lloyd.
I also found the pdf download quite fascinating , so thanks for that.
A bit embarrassed too, as I hadn't a clue that the GL stood for Germanischer Lloyd.
022516
Re: Acceptable Plywood Standards
Hi Chris,
No problem, but I'm no expert, I have just tried to understand the issues and as you say, I have a passion about woodworking and wooden aircraft building that I'd like to share and am very keen to learn more myself.
Not sure where Mark is going with this as he hasn't responded, but hopefully he'll get on with building a very fine Pietenpol.
Regards,
Colin
No problem, but I'm no expert, I have just tried to understand the issues and as you say, I have a passion about woodworking and wooden aircraft building that I'd like to share and am very keen to learn more myself.
Not sure where Mark is going with this as he hasn't responded, but hopefully he'll get on with building a very fine Pietenpol.
Regards,
Colin
018841
Colin Cheese
Colin Cheese