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Oct 23, 2019, 01:57 PM
I fly, therefore, I crash!!!
SteveT.'s Avatar
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Discussion

Plywood used in the Airtronics Oly ll?


Would somebody be so kind as to tell me what kind of plywood was used in the front of the Oly ll fuselage. I have the plans, and a laser cutter and have most of the parts cut out to build one, but the plans call for 1/8" 'Air-ply'. Is this lite-ply or 3-ply birch plywood? I have the 3 ply birch but can get the lite ply.

Thanks.

SteveT.
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Oct 23, 2019, 02:04 PM
Duane, LSF IV
Wazmo's Avatar
"Air-ply" is mostly likely an abbreviation of aircraft plywood. I'd go with the 3-ply birch at least, or 5-ply if you can get it.
Oct 23, 2019, 02:23 PM
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whacker's Avatar
delete, double post
Oct 23, 2019, 02:25 PM
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whacker's Avatar
the ATX sagitta and aquila kits of the day used lite ply.

the nice Birch ply was used for formers, as well as root rib caps, gussets at the U/S of wing root etc


it was 1/8, some of the lite ply available these days is 3 mm close enough.


I could not imagine some of that beautiful 1/8 birch ply being needed, then again I'm not behind the wheel either

whacker

in the windy Waughs River Valley
Last edited by whacker; Oct 23, 2019 at 02:35 PM.
Oct 23, 2019, 03:28 PM
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Ditto Wacher's saying it's what we now generally call "lite ply".

Outerzone has, in addition to the RCMagazine's building article, also has the Airtronics manual for the Olympic II, wherein the front fuselage side pieces are called "lightweight ply". Back then - late 1960s, 1970s - references to ply either meant the white shaded (poplar?) three layer "lite ply" or the many more layered, heavier, stronger "aircraft" plywood. I went to my stash of legacy aircraft ply, and the 1/8" thick stuff has FIVE layers.

That said, I personally am not thrilled with lite ply as it often comes warped.....and for many of our applications its use results in overbuilding, unnecessary weight. I also suspect that its presence in kits is due to lower cost over balsa. Another fuselage construction for the Olympic II that would work would be full length fuselage of 1/8" balsa, with a front fuselage to wing trailing edge doubler of 1/64" ply/or stiffening of the same front fuselage sides with 1/8" by 1/4" spruce longerons (on which the servo rails could also be hung)….. but I would use 1/8" lite ply or 3/32" aircraft ply for the front fuselage bottom for ding resistance from landings.

Michael in Ontario, Canada
Oct 23, 2019, 03:39 PM
Balsa breaks better
Thermaler's Avatar
My first Oly was stock light ply/balsa fuselage.
My second one was 3/32" real plywood and 3/32" balsa.

Used 2 oz less lead in the nose with the 3/32" . . .

Joe

Balsa Breaks Better
Woodies Forever
Oct 23, 2019, 04:51 PM
I fly, therefore, I crash!!!
SteveT.'s Avatar
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Thanks guys... I actually started building it with the 3 ply birch ply, but felt it was a bit heavy. I have build a couple of the Oly ll's but that's when they were new planes, and I just didn't remember for sure. As noted, I have my own laser cutter, but it only cuts up to 12 X 20" so I have had to splice the fuselage sides. I have used a locking joint, and put a balsa backing piece behind it, so I feel it will be plenty strong.

SteveT.
Latest blog entry: My shop....
Oct 23, 2019, 08:20 PM
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Two places for ply


National Balsa (New England) and Aircraft Spruce (full scale supplier(CA)) both have 5 ply 1/8" I think both places sell 12" x 48" sheets. I seem to remember that there is a very slight curve as I understand that 3 and 5 ply come in rolls from the maker. I do know that both the 3 and 5 ply have poor middle plys. Crumbly. I found this when I had to sand away two layers to mate to aft balsa sheet.

Both are very good companies to work with.

cheers
Jim







Quote:
Originally Posted by SteveT.
Would somebody be so kind as to tell me what kind of plywood was used in the front of the Oly ll fuselage. I have the plans, and a laser cutter and have most of the parts cut out to build one, but the plans call for 1/8" 'Air-ply'. Is this lite-ply or 3-ply birch plywood? I have the 3 ply birch but can get the lite ply.

Thanks.

SteveT.
Oct 23, 2019, 08:39 PM
I fly, therefore, I crash!!!
SteveT.'s Avatar
Thread OP
Guys, I know 'where' to get wood, My question is for somebody that actually has an Oly ll that can tell me what was actually in the kit
originally.

I.E. here is a list of some I use..


Specialized Balsa

National Balsa

AC supply

Balsa USA

Midwest Products

Balsa Wood Inc.

Balsa Central

Sig MFG.

Balsa Wood shop

And not all 3 ply ply plywood has a 'crumbly' core. If you get it from a good supplier it doesn't

Aircraft Plywood is a very good source of aircraft plywood, including some very good laser cuttable 3 ply with a melamine glue and a basswood core.

SteveT.
Last edited by SteveT.; Oct 24, 2019 at 01:19 PM.
Oct 23, 2019, 09:28 PM
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prodjx's Avatar
I'll check my plan's but lite ply is poplar, three ply. And the ply should be of the same thickness for each layer.
Oct 23, 2019, 09:39 PM
I fly, therefore, I crash!!!
SteveT.'s Avatar
Thread OP
Thank you. As noted, the Airtronics plans I have say 'Air-ply'.

SteveT.
Latest blog entry: My shop....
Oct 24, 2019, 02:19 AM
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harborflyer's Avatar
Gentlemen,
The "expert" to ask would be Larry Jolly, he worked there "in the day"
Would have more "weight" than myself !

Ross
Oct 24, 2019, 02:55 AM
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whacker's Avatar

Atx oly ii


Sagitta 900 parts lists are available. Perhaps some of the OLY II kits had them.

Google OLY II sailplane Kits, perhaps you'll find KIt Pics so you can see what was there
(beware some Kits have had parts replaced or taken)

Of course the OLY II came earlier

knowing Airtronics they had a method, and built upon that for commonality and ease of production.

the ATX OLy II kit i had did not include a Parts List,

You can also get Ply from B UsA, I believe it's 3 mm though (confirm)

You may find that things changed over the years with the production of this and there was some variance in supplied Materials , these Kits to my recollection could be purchased for 36$ from INDY in 1978

With respect to Build Design

I always liked the Lite ply forward, nice straight balsa aft, sized big enough so it could be trued at time of build. * long fuse aft balsa warps in kits*
and lite ply at bottom to aft of TE, but joint terminations / transitions placed such that they are not in vertical plane, that jig saw interlock is an improvement.

Just when you thought it was all clear, apparently Ed Whyte (Whyte Wings ) kitted some of the later Airtronics OLY II Kits

larger wing spars and joiner rod. BOX Label appears to be the same as earlier Kits

Not sure what Ed did, but a 5/16 nitrided wing rod (ejector pin material) would work well

whacker
Last edited by whacker; Oct 24, 2019 at 03:32 AM.
Oct 24, 2019, 12:48 PM
I fly, therefore, I crash!!!
SteveT.'s Avatar
Thread OP
I have already cut everything for my plane that can be cut with my laser, the only thing left to cut is the wing tips as they are too thick. All the ribs, elevators, joiners etc. are ready to go.

Just as noted, once I started building the fuselage it felt heavy to me using the 3 ply birch plywood, so, I have ordered some lite ply.

As to Larry Jolly working there, I did not know this, and I will contact him.

SteveT.
Last edited by SteveT.; Oct 24, 2019 at 01:10 PM.
Oct 24, 2019, 04:54 PM
Registered User
If I was building an Oly II from scratch, I'd consider a ply /balsa/ply sandwich using 1/64 or 1/32 ply. Best of both materials. Or I might use ply on the inside and glass the outside.

I might try scarfing instead of an interlock.


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