[NSRCA-discussion] An education in balsa usage for pattern

[jeffghughes at comcast.net]

When I was at Bendix we made helicopter tie bars that we pulled to destruction once a year. Took just shy of a million pounds, sounded like artillary fire when they broke. 

-------------- Original message -------------- 
From: "Bill Glaze" <billglaze at triad.rr.com> 

In United's school, we were told, as an aside and a pure point of interest, that after functional testing on the 747, the test team was given the order "test to destruction" on the wing.  It was pulled upward until the tips were about 6' apart before there was a "catastrophic failure."(!!)  At least, that's what the school told us.  I was in 767 school at the time.
Bill Glaze
----- Original Message ----- 
From: rcmaster199 at aol.com 
To: nsrca-discussion at lists.nsrca.org 
Sent: Wednesday, March 29, 2006 10:00 PM
Subject: Re: [NSRCA-discussion] An education in balsa usage for pattern


Wayne, 

Oh yeah babe, isn't that a kick? A 10 year old being introduced to the fine art of balsa structure and mechanical engineering design. Fabulous!!

Give that teacher a bonus. 

Digressing a bit from the Balsa theme, Warren trusses, IF I remember right, are basis for airliner spars among other things. Several years ago, as a key supplier to Boeing, we had opportunity to witness the triple 7 spar test where the wing was folded to determine g-loading capability. Impressive test. 

Matt
 
-----Original Message-----
From: Wayne Galligan <wgalligan at goodsonacura.com>
To: NSRCA Mailing List <nsrca-discussion at lists.nsrca.org>
Sent: Wed, 29 Mar 2006 08:35:57 -0600
Subject: Re: [NSRCA-discussion] An education in balsa usage for pattern


Matt,

My son did his 5th grade science project using balsa construction.  His project was to determine what bridge truss design held the most weight for a given span.  It was truly amazing how much weight the structure would hold.  The spans he built where 7"x7"x24" and weighted 1.5 oz, made of 1/4" square med grade balsa glued together with thin c/a.  The Warren truss held 42 lbs before collapsing and the two other structures were close behind holding 32 to 38 lbs.  It was a learning experience for both of us.  It gave me a better understanding of how certain truss structure builds stiffness, strength and be light weight.   

Wayne Galligan
----- Original Message ----- 
From: rcmaster199 at aol.com 
To: nsrca-discussion at lists.nsrca.org 
Sent: Tuesday, March 28, 2006 6:58 PM
Subject: Re: [NSRCA-discussion] An education in balsa usage for pattern


Balsa is pretty amazing stuff overall, particularly for a natural material. The Xylem that makes up much of the superstructure of any wood (that's what we commonly hear as grain), is essentially a huge number of tubes arrayed side by side, but interconnected along the length. The tubes serve a terrific function in the long direction and the interconnects make the structure have reasonable transverse strength as well. 

The closest thing manmade that will surpass it in terms of mechanical strength vs flex vs weight vs cost will likely be Buckytube if you excluded the cost. That's just in laboratories now, being made in very small quantities supporting very high end applications. This stuff is the true unobtainium that some have complained about. But that's another subject.

There used to be an annual competition in colleges where a very small, known quantity of balsa and glue were used creatively by students to build some kind of support structure like a small bridge. These things would hold unbelievable amounts of weight. 

Alas, the weakness is shock loading. 

Matt
 
-----Original Message-----
From: Adam Glatt <adam.g at sasktel.net>
To: NSRCA Mailing List <nsrca-discussion at lists.nsrca.org>
Sent: Tue, 28 Mar 2006 16:44:02 -0600
Subject: Re: [NSRCA-discussion] An education in balsa usage for pattern


Not directly applicable to pattern, but certainly a good start:
Buy and build a Stevens Aeromodel kit. The planes are small (35-50" 
span, 1-2.5lbs) and electric powered. I'm about 1/2 done building the 
Edge 540, and am actually enjoying the build because I am constantly in 
awe of the genius wood design and its results (consider that this Edge 
540 is 40-sized, but will weigh only 2lbs with more performance than all 
but the most dedicated 40-sized 3D glow planes).

-Adam

White, Chris wrote:
>
> Can anyone tell me where a person can get a "Crash" course in learning 
> about balsa weights and strength and its proper use in balsa pattern 
> models.
>
> I notice a few years ago that in the 99 world champs most of the 
> Japanese pilots models were balsa and light weight too. It seems that 
> everything I read of late seems to indicate that light weight and 
> strength only come with composite construction.
>
> Thanks..Chris
>
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