Cyparis, Spruce and Basswood, what are their qualities and which would be best for my next build?

[David Davis]

I am at the planning stage before building David Hurrell's 1/4 scale Fokker Triplane over the winter; plan MW 3005 from Sarik. On the plan it states that the fuselage should be made from "...1.4" sq cyparis or genuine spruce would be acceptable."

 

I am completely unfamiliar with cyparis and I have not been able to find a supplier of this wood.

 

I have used basswood in place of balsa for longerons on smaller models, my Barons for example. This has produced a stronger fuselage at the expense of some weight gain.

 

I have not used spruce since I was a youth but it is readily available. However, I have read posts which do not recommend using spruce as it is too oily and apparently it's difficult to get a good joint between uprights and longerons. I cannot recall having any adhesion problems with spruce when I used it in combat wings over fifty years ago!

 

Given all of the above what are the quallities of the three woods and which glue would you use on which wood if you were building this model?

 

In the event of my not being able to find cyparis which would you prefer from spruce or basswood if you were building this model?

 

I intend to replicate David Hurrell's method of building by reinforcing each joint with 1/64" ply triangles.

[Ace]

I get my my Cyparis from Solutions (one by one) who are based in the NE and attend my local LMA Elvington show. I believe it's not an easy wood to source. 

I feel it is superior to spruce in that it bends without splitting, sands and shapes easily and has little or no visible grain which give it good shock absorbing qualities. Probably weighs less than spruce and can't say I have had any issues with PVA   or Aliphatic.

The basewood I have used looks/feels and works like VERY hard balsa.

As for the technical differences others will have to chip in.

 

Edited August 28, 2021 by Ace

[stu knowles]

google 'Stuart Solomon Cyparis'  He is the only supplier that I am aware of

 

Contact Stuart at Solutions - he does some timber in 6 ft length, mainly cyparis.
Stuart@solutions. 01207 544414

 

Ha, Ace beat me to it!

[Don Fry]

I go down the the local DIY store, and buy the pine they sell, it’s Auverné Pine, or White pine. Comes in 2 meter lengths, no knots, straight grain, and absolutely perfect. Cheap too. And will do the lower wing spars of a Triplane in one piece, no joints. Fine with Apliphatic glues. 

PS, Sorry lads, David and I are in France. And there is a lot more good wood here, in greater varieties, at smaller prices.

Mind, short nose, pine back end? I’ve got a Flair 1/4 scale. Semi scale, a longer nose, balsa back end, 6 mm square framing. Mine has a Zenoah up front, so it’s not a lightweight power plant, and it balances as is.

[David Davis]

I plan to fit an old Laser 150 V Twin which is no lightweight either.

[Andy Gates]

With spruce I generally give it a light sand before gluing using PVA or in places where strength is needed - epoxy.

 

Bass is nicer to use but I don't find it quite as strong as spruce.

 

Never used Cyparis so I can't comment.

[Christopher Wolfe]

As Andy said, after  a light sanding and spruce is great material for where a bit of extra strength is required without adding too much weight (I like it for wing spars). Aliphatic resin or epoxy is fine.

 

I seem to recall that real aeroplanes (two wings and wire) were made of spruce and even Howard Hughes chose this for his giant so maybe the aeronautical engineers figured out the answers many years ago.

 

Chris

[David Davis]

Thanks gentlemen.

 

It looks like it's going to be spruce. I'll have a day out in Chateauroux next week and see if I can find some 6mm square spruce for the fuselage longerons and 12mm x 3mm spruce for the wing spars. Hurrell has replicated the structure of the Dr1 in his model. The wing spars are in the form of two boxes joined together top and bottom by 1/64" plywood to produce a single, immensely strong box spar. In practise the early triplanes were so badly built that the top wings used to collapse but that will not be a problem with my model, though I'll probably use balsa for the webs. Hurrell suggests that he could have used balsa for the webs in his build article. I need to buy some varnish for the front door before the winter arrives anyway.

Edited August 29, 2021 by David Davis