How do you tell which is high quality balsa?

jyoder111 · Apr 21, 2001, 09:52 PM

Most E-flight articles say to chose your wood wisely. At the hobby shop, how am I supposed to tell which piece is higher quality. Also, what's the difference between A-grain, C-grain, etc.

Thanks

Jesse

El Pe · Apr 22, 2001, 12:41 AM

Jesse, you are in a whole 'nother country here. There have been several articles in various model mags over the years covering this. I might be able to dig one out in time, however I basically choose wood based on the size/weight of the model, what part of the plane the wood is for, whether is a key structural part of not (leading, trailing edges, longerons, etc.)

When picking wood, I first check weight, then how straight the piece is, followed by flexibility. Generally speaking you can make a light piece stronger by reinforcing with cyano. or 6/10 oz fibreglass and cyano. or 1/64" ply, even light card stock, but you can't make a heavy piece lighter.

There is a whole raft more as picking the wood can be the pass/fail or whether you have an anchor or or an airplane. I'll see if I can find one of the articles for you. Meanwhile, you might do a search in the E-zone here and see what you come up with. these guys are pretty sharp. Probably a couple hundred thousand years building experience, all told.

Lee

James Frolik · Apr 22, 2001, 04:46 AM

Sometimes when sorting through a balsa selection I will notice one sheet of balsa is definitely stiffer and feel somewhat heavier than another (when comparing the same size and thickness). Maybe I'll also notice the grain in areas is mildly darker than another sheet; it may even appear kind of warped or bowed. This often tells me the sheet is heavier than I would like, and if it's not straight it could possibly stress the lightweigth model I plan to construct. The part of the tree from which the sheet came was likely denser. But this doesn't mean it couldn't be used satisfactorily.

It's just than most electric flyers strive to build as light as possible, and some go to many lengths just to save even a couple extra grams weight. A few modelers I know select their wood very carefully, even taking a gram scale to the store with them to weight each sheet for comparison. And once they buy their wood, they leave it stacked and slightly weighted in a VERY dry place for a year or two in order to, shall I say, dry it out even more and therefore reduce the weight even further. This may even make it more "brittle," if that's the right word, but once used in construction a model's overall supporting structure still remains strong.

When talking about an all-balsa eflight model, depending on its size the resulting weight saving can be significant. But you don't necessarily have to store you balsa for a few years to achieve this.

[This message has been edited by James Frolik (edited 04-22-2001).]

Bill Harris · Apr 22, 2001, 02:41 PM

Here is a WebSite with a page on "Balsa wood 101":
http://www.mentornet.org/balsa3.htm

--Bill

SteveS · Apr 22, 2001, 06:15 PM

Hi Jesse,
If you will try to find the closest Free Flight (FF) club, you will have located the modelers that know more about balsa than most any other segment of the sport. In particular the indoor flyers have taken balsa selection to a higher plane. It might seem silly to carry a gram scale to the hobby shop, but the weight savings can quickly amount to 10% on a S400 model.
Good luck,
Steve Smith
Atlanta

jyoder111 · Apr 22, 2001, 09:37 PM

Thanks a lot for your help.

Jesse

steve glass · Apr 24, 2001, 07:51 AM

Hi,

Select wood that weighs less than 10gm. for each 1mm. in thickness for a 4" x 36" sheet. e.g. 3mm. sheet should weigh 30 gm. or less, etc..

Hold the wood up to the light to look for an even density throughout.

Get a few sheets of harder straight, close grained wood for spars etc.

Slowly build your own stash of quality balsa.

Steve

leccyflyer · Apr 25, 2001, 03:34 AM

Hi

Taking a small letter scale to the LHS when buying your balsa isn't dificult- I use a simple little counterweighted postal scale -available from most good stationary suppliers -that weighs from 0-100grams and is 2.5 inches long with a crocodile clip to hold the letter. Attach a piece of masking tape to the croc clip so as to not damage the balsa as you weigh it.

It is then a simple task to prepare a set of ideal weights for each common balsa size and I have a little printed table (just 2 inches square) inside the soft case of the letter scale.

Having selected the lightest and straightest finest balsa with the characteristics you are looking for you can then grade it, write the weight on the sheet and store it or proceed to construct the perfect model. Or like me you can then proceed to stick it in a balsa rack and forget about it until you need to snap a chunk off to make an emergency repair thereby ruining the carefully selected sheet

cheers

Brian

Apr 21, 2001, 09:52 PM	#1
jyoder111 Registered User Join Date: Nov 2000 Location: Lancaster, PA, USA Posts: 97	How do you tell which is high quality balsa? Most E-flight articles say to chose your wood wisely. At the hobby shop, how am I supposed to tell which piece is higher quality. Also, what's the difference between A-grain, C-grain, etc. Thanks Jesse

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Apr 22, 2001, 12:41 AM	#2
El Pe Member Join Date: Jan 2001 Location: Northwest Territory Posts: 202	Jesse, you are in a whole 'nother country here. There have been several articles in various model mags over the years covering this. I might be able to dig one out in time, however I basically choose wood based on the size/weight of the model, what part of the plane the wood is for, whether is a key structural part of not (leading, trailing edges, longerons, etc.) When picking wood, I first check weight, then how straight the piece is, followed by flexibility. Generally speaking you can make a light piece stronger by reinforcing with cyano. or 6/10 oz fibreglass and cyano. or 1/64" ply, even light card stock, but you can't make a heavy piece lighter. There is a whole raft more as picking the wood can be the pass/fail or whether you have an anchor or or an airplane. I'll see if I can find one of the articles for you. Meanwhile, you might do a search in the E-zone here and see what you come up with. these guys are pretty sharp. Probably a couple hundred thousand years building experience, all told. Lee

Apr 22, 2001, 04:46 AM	#3
James Frolik Long-Time Member Join Date: Dec 1996 Location: Cologne, Germany Posts: 1,715	Sometimes when sorting through a balsa selection I will notice one sheet of balsa is definitely stiffer and feel somewhat heavier than another (when comparing the same size and thickness). Maybe I'll also notice the grain in areas is mildly darker than another sheet; it may even appear kind of warped or bowed. This often tells me the sheet is heavier than I would like, and if it's not straight it could possibly stress the lightweigth model I plan to construct. The part of the tree from which the sheet came was likely denser. But this doesn't mean it couldn't be used satisfactorily. It's just than most electric flyers strive to build as light as possible, and some go to many lengths just to save even a couple extra grams weight. A few modelers I know select their wood very carefully, even taking a gram scale to the store with them to weight each sheet for comparison. And once they buy their wood, they leave it stacked and slightly weighted in a VERY dry place for a year or two in order to, shall I say, dry it out even more and therefore reduce the weight even further. This may even make it more "brittle," if that's the right word, but once used in construction a model's overall supporting structure still remains strong. When talking about an all-balsa eflight model, depending on its size the resulting weight saving can be significant. But you don't necessarily have to store you balsa for a few years to achieve this. [This message has been edited by James Frolik (edited 04-22-2001).]

Apr 22, 2001, 02:41 PM	#4
Bill Harris Shrug... Join Date: May 2000 Location: Backwoods Alabama Posts: 2,924	Here is a WebSite with a page on "Balsa wood 101": http://www.mentornet.org/balsa3.htm --Bill

Apr 22, 2001, 06:15 PM	#5
SteveS Registered User Join Date: Jun 2000 Location: Atlanta, GA, USA Posts: 52	Hi Jesse, If you will try to find the closest Free Flight (FF) club, you will have located the modelers that know more about balsa than most any other segment of the sport. In particular the indoor flyers have taken balsa selection to a higher plane. It might seem silly to carry a gram scale to the hobby shop, but the weight savings can quickly amount to 10% on a S400 model. Good luck, Steve Smith Atlanta

Apr 22, 2001, 09:37 PM	#6
jyoder111 Registered User Join Date: Nov 2000 Location: Lancaster, PA, USA Posts: 97	Thanks a lot for your help. Jesse

Apr 24, 2001, 07:51 AM	#7
steve glass Registered User Join Date: Jan 2001 Location: england Posts: 162	Hi, Select wood that weighs less than 10gm. for each 1mm. in thickness for a 4" x 36" sheet. e.g. 3mm. sheet should weigh 30 gm. or less, etc.. Hold the wood up to the light to look for an even density throughout. Get a few sheets of harder straight, close grained wood for spars etc. Slowly build your own stash of quality balsa. Steve

Apr 25, 2001, 03:34 AM	#8
leccyflyer Get One Up! Join Date: Sep 2000 Location: Cheshire, England Posts: 9,302	Hi Taking a small letter scale to the LHS when buying your balsa isn't dificult- I use a simple little counterweighted postal scale -available from most good stationary suppliers -that weighs from 0-100grams and is 2.5 inches long with a crocodile clip to hold the letter. Attach a piece of masking tape to the croc clip so as to not damage the balsa as you weigh it. It is then a simple task to prepare a set of ideal weights for each common balsa size and I have a little printed table (just 2 inches square) inside the soft case of the letter scale. Having selected the lightest and straightest finest balsa with the characteristics you are looking for you can then grade it, write the weight on the sheet and store it or proceed to construct the perfect model. Or like me you can then proceed to stick it in a balsa rack and forget about it until you need to snap a chunk off to make an emergency repair thereby ruining the carefully selected sheet cheers Brian