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Ok guys...i found out one of my co workers at the FAA owns a CNC router. He can do anything from signs to tile (amazing what can be done there!) to wood. That's where he got my interest. I asked him how he does it and if he could cut plywood ribs out easily if I supplied the plans. Sure enough he had a buddy scan in the full size drawings from the 6-1-1998 plans...Les Homan says on the sheet 1 "we have taken the original drawings and put them on autocad..." Dated 1-12-1999. I believe these to be the newest version of plans. Please correct me if I'm wrong!
He has now scanned them in and will be doing a few samples soon.
As to what wood to use...I've officially now seen it all. From 12 ply Finnish birch...to 5 ply Mahogany to 3 ply royal marine a-a fir. The plans I have call for 5ply aircraft mahogany for the ribs. Buttttt these plans were made about the same time our own NDTOO says he got a factory kit from Starduster Corp and he was supplied with 12ply Finnish birch and told that's what to use by the factory if I recall the other thread correctly (again correct me if I'm remembering things incorrectly). All that said my wings look to be 3 ply Royal marine and others I've seen (I have bought some extra stuff that included some wings etc that are partially built...they also are 3 ply Royal marine...unfortunately I don't believe they are any good because they weren't varnished and left in hangar for many years. But there is almost a complete set of wing hardware that is good...maybe I'll build another of I can get this one done!) so it's basically builders choice between those I guess. I think I will use the the mahogany 5ply unless someone has a reason for one of the others I should know????? Please, let's hear opinions on this and the whys.
BTW HERE IS TODAYS AIRCRAFT SPRUCE COSTS ON THE PLYWOOD.
4'x4' 12ply Finish Birch $112.75
.95lbs per sq foot
Quality Birch Aircraft grade plywood produced to AB/B grade on all thicknesses. Meets GL2
4'x4' 5ply mahogany $121.97
Says 4'x8' sheet of 1/4" weighs 25lbs so that's 12.5lbs for a 4'x4' and .78lbs for 1 sq foot.
American-made structural aircraft-grade plywood is made of imported African Mahogony veneers laminated in a hot press to hardwood cores of Poplar or Bass wood with waterproof glue. Will meet all requirements of specification MIL-P-6070, which calls for shear testing after immersion in boiling water for 3 hours. Far superior to many plywoods in which all plies are 1/16 inch thick and laminated in a cold press to make up the total thickness. Tests should be made on cold press plywoods before use on aerobatic aircraft. Available in 45° and 90°
4'x4' 3ply Royal marine $31.88
(I've sent a message to ask the weight for a sq foot...will update when I find out)
UPDATE ACS REPLIED AND IT IS .8125lbs per sq. ft.
First quality marine plywood that meets or exceeds requirements of specifications PSI-74. All are Douglas Fir. Insist on A-A grade for your aircraft!
Seems like any of these will be perfectly fine. I know my plane had several hundred hours with no wing issues because of wood type. And we know the factory was selling the 12 ply Finnish birch. But seems it was designed using mahogany. The weight seems like a fairly big deal here. .95lbs for the birch vs .78 for the mahogany and unknown yet on the Royal marine. Almost a 1/4" pound per sq foot of 1/4" plywood seems like maybe you could save 5-10lbs I'd think if you used the mahogany instead of birch?
For the weight conscious crowd it seems a easy choice and if one is doing it from scratch this seems like a perfect place to turn a little extra money into a little less weight. The cost for birch vs mahogany is fair close. The Royal marine is down right cheap in comparison.
So after that long winded question and comparison is there any interest from anyone wanting a set of ribs? Price would be dependent on wood choice obviously. My buddy says the actual cutting wouldn't be very much...he hasn't given a price yet until he does a few practice ribs to see how fast he can cut with no chips on edges. I'll keep you posted but I wanted to see if there was any interest at all before I order wood for myself. (It will save money to order all the wood at once vs me order mine then order more etc).
I have checked my ribs from my right lower wing and they are close...but not exactly like the plans. I'm actually just going to trace mine and have him scan those drawings to produce my set. I figure my plane flew good how it was so I'm not going to reinvent the wheel. AND I'm hoping my other wings will prove to be good when I inspect them...although I'm planning on them being exactly like this one minus the cracked rear spar...the glue joints were done at the same time sooooo they also probably need repair or replacement also. We could do this for anyone also if you don't want to use the ribs as they are drawn in the 1998-1999 plans...if you are reading this NDTOO, what plans were your ribs built from just to give us an idea how the plans wings will turn out.
I'd be glad to work with anyone else that may have the metal parts scanned in for water jet so we could basically have a kit for builders.
He has now scanned them in and will be doing a few samples soon.
As to what wood to use...I've officially now seen it all. From 12 ply Finnish birch...to 5 ply Mahogany to 3 ply royal marine a-a fir. The plans I have call for 5ply aircraft mahogany for the ribs. Buttttt these plans were made about the same time our own NDTOO says he got a factory kit from Starduster Corp and he was supplied with 12ply Finnish birch and told that's what to use by the factory if I recall the other thread correctly (again correct me if I'm remembering things incorrectly). All that said my wings look to be 3 ply Royal marine and others I've seen (I have bought some extra stuff that included some wings etc that are partially built...they also are 3 ply Royal marine...unfortunately I don't believe they are any good because they weren't varnished and left in hangar for many years. But there is almost a complete set of wing hardware that is good...maybe I'll build another of I can get this one done!) so it's basically builders choice between those I guess. I think I will use the the mahogany 5ply unless someone has a reason for one of the others I should know????? Please, let's hear opinions on this and the whys.
BTW HERE IS TODAYS AIRCRAFT SPRUCE COSTS ON THE PLYWOOD.
4'x4' 12ply Finish Birch $112.75
.95lbs per sq foot
Quality Birch Aircraft grade plywood produced to AB/B grade on all thicknesses. Meets GL2
4'x4' 5ply mahogany $121.97
Says 4'x8' sheet of 1/4" weighs 25lbs so that's 12.5lbs for a 4'x4' and .78lbs for 1 sq foot.
American-made structural aircraft-grade plywood is made of imported African Mahogony veneers laminated in a hot press to hardwood cores of Poplar or Bass wood with waterproof glue. Will meet all requirements of specification MIL-P-6070, which calls for shear testing after immersion in boiling water for 3 hours. Far superior to many plywoods in which all plies are 1/16 inch thick and laminated in a cold press to make up the total thickness. Tests should be made on cold press plywoods before use on aerobatic aircraft. Available in 45° and 90°
4'x4' 3ply Royal marine $31.88
(I've sent a message to ask the weight for a sq foot...will update when I find out)
UPDATE ACS REPLIED AND IT IS .8125lbs per sq. ft.
First quality marine plywood that meets or exceeds requirements of specifications PSI-74. All are Douglas Fir. Insist on A-A grade for your aircraft!
Seems like any of these will be perfectly fine. I know my plane had several hundred hours with no wing issues because of wood type. And we know the factory was selling the 12 ply Finnish birch. But seems it was designed using mahogany. The weight seems like a fairly big deal here. .95lbs for the birch vs .78 for the mahogany and unknown yet on the Royal marine. Almost a 1/4" pound per sq foot of 1/4" plywood seems like maybe you could save 5-10lbs I'd think if you used the mahogany instead of birch?
For the weight conscious crowd it seems a easy choice and if one is doing it from scratch this seems like a perfect place to turn a little extra money into a little less weight. The cost for birch vs mahogany is fair close. The Royal marine is down right cheap in comparison.
So after that long winded question and comparison is there any interest from anyone wanting a set of ribs? Price would be dependent on wood choice obviously. My buddy says the actual cutting wouldn't be very much...he hasn't given a price yet until he does a few practice ribs to see how fast he can cut with no chips on edges. I'll keep you posted but I wanted to see if there was any interest at all before I order wood for myself. (It will save money to order all the wood at once vs me order mine then order more etc).
I have checked my ribs from my right lower wing and they are close...but not exactly like the plans. I'm actually just going to trace mine and have him scan those drawings to produce my set. I figure my plane flew good how it was so I'm not going to reinvent the wheel. AND I'm hoping my other wings will prove to be good when I inspect them...although I'm planning on them being exactly like this one minus the cracked rear spar...the glue joints were done at the same time sooooo they also probably need repair or replacement also. We could do this for anyone also if you don't want to use the ribs as they are drawn in the 1998-1999 plans...if you are reading this NDTOO, what plans were your ribs built from just to give us an idea how the plans wings will turn out.
I'd be glad to work with anyone else that may have the metal parts scanned in for water jet so we could basically have a kit for builders.
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