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Author Topic: The paradigms, they are a changin' (With apologies to Bob Dylan...)  (Read 1285 times)

Bob Hunt

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Hi all:
This post will be my attempt to help all of us understand the realities of the current balsa situation and how we can help ourselves immensely from now on into the future to deal with these realities. I’m going to post this piece on several forums because I believe the need for the following information is critical to model airplane building in the 21st century.

First the medicine:

The days of 4 to 6 pound, clear, straight grain, 4 to 6 inch wide in-one-piece, readily obtainable, inexpensive balsa wood are essentially gone. Please read that sentence again. It is essential that all of us face the realities of the situation. Sure, we will occasionally be able to find isolated stashes of Ecuadorian Gold, and we should snap up those opportunities when and where they present themselves. Those of us who have been at this for awhile can remember the amazingly clear and consistent contest grade balsa that we used to be able to get on a regular basis from several suppliers. That type of wood in the quantities in which we used to receive it simply isn’t available anymore.

Where has all the balsa gone? (Sounds like an old Peter, Paul and Mary song…) The real question is, “Where is all the balsa going?” What I’m going relate now may seem incredulous, but I have checked the facts with several people who really know the balsa business and it is apparently true. A few years back most of the balsa was going to the ship building industry to line the holds and hulls in super tankers. Perhaps someone who knows more about that construction will jump in here and elaborate. Today most of the wood that’s imported is going into (and this is so ironic…) making propellers! No, not 12 x 6 inch props and the like, but rather 30 and 40 and 50 and 60 foot diameter wind farm props. The word I get is the manufacturers of those devices are purchasing huge amounts of mill run balsa from which to make the blades for those props. They apparently don’t care too much about the densities of the wood and so are just buying it up wholesale. And with it, virtually all of the “good” stuff as well.

Add to that fact that there just isn’t as much soft, light, straight grain wood coming out of the forests anymore, and you can understand that we are lucky to get what we do get! The above will no doubt cause much debate here, but all the debate in the world will not change the central fact (The 4 to 6 pound Gorilla in the room if you will…) that “our father’s balsa” is not the kind of stuff we are able to get in quantity these days. Nuff medicine?

Now the Honey:

Take great heart, because there is an answer to this problem for us. However, that answer will involve all of us accepting some new paradigms. As most of you know I’m back pretty much full time in the model airplane component business. As that fact became more known, my business doubled, and is now on its way to tripling. I’m a happy guy… What has been difficult is getting enough wood in the sizes and densities requested to fulfill my covered foam wing orders. This is not the first time this has happened to me. Back in the late 1960s and all through the 1970s I had a very successful concern that specialized in custom foam wing manufacturing (Control Line Specialties/Control Specialties). At that time I was able to purchase reasonably good quality wood, but even then getting a sufficient amount of 1/16 inch thick, 4 to 6 pound stock was a bear.

The answer was simple: Use thinner wood in heavier densities. I started producing wings covered with .047 (3/64 inch thick) balsa, and even many covered with .032 (1/32 inch thick) balsa. Look at the logic: A piece of 1/32,  10 pound density balsa, in a given length and width, weighs EXACTLY the same as a piece of 5 pound density 1/16 inch thick balsa of the same length and width dimensions. Please read that sentence again…

I’d say that 90 to 95 percent of the wings I produced in the aforementioned era were covered with the .047 material, and that included many, many wings used by the very top competitors in Stunt in the country. The overall result was the ability to keep pace with the incredible number of wing orders and provide strong, light components.

Once my clientele had bought into this concept, they found many other advantages to the shift in the wood paradigm. The heavier density wood had much better grain integrity. A good deal of soft wood contains “wind checks.”  Wind checks are chord wise cracks in the balsa sheet caused by the parent tree having swayed in the wind while growing. These cracks typically form across the trunk of a light density wood tree in several areas. This wood is not ideal for model building; especially where we need the strength of uninterrupted grain structure – such as in foam wing skinning. 

The heavier density wood has a couple of other advantages: Being denser it will not soak up as much glue during the covering process, nor modeling dope during the finishing process!  Soft wood acts just like a sponge! You can also apply a better quality finish over a harder surface than you can over a softer one.

Okay, the facts are that by using the denser balsa in thinner sections we can achieve as light or even lighter wings of a given size that will also accept a lighter, better finish. But the biggest factor is that this type of balsa should be easily available to us through any one of the balsa suppliers on an ongoing basis.

My advice is that when you are ordering custom thickness balsa wood, don’t order just a few sheets of it. Balsa suppliers will gladly adjust their cutting and sanding equipment to supply you with the thicknesses you desire, but meet them half way by ordering enough to make it worth their while to make those adjustments.

The above was accepted technology in the foam wing business back in the 1970s, and I don’t know what happened to change the paradigm back to the use of lighter density, thicker sizes in the interim. The good news is that we can once again use this avenue to have our cake, eat it too, and then all go out for a big desert afterwards.

My wood supplier has informed me that he can supply virtually all the wood I need in thinner, higher density form. That’s the direction I’m heading. I will continue to order and offer 4 to 6 pound 1/16 and/or 3/32 as requested, but the prices will be staggering as this type of wood is at a super premium these days. My prices will, in turn, reflect what I have to pay to get it. Which brings me to the last point I want to make in this post: Major manufacturers do not cater to us in large part because we are unrealistic in our perception of what hobby items should cost. Times have changed, and we must face the facts that the prices we paid for quality merchandise 20 years ago are not the prices we should expect to pay today. This is especially true of the balsa we use. If you think about it, balsa is about the least expensive major component in any Stunt model. If we had to pay double or even triple to get good balsa materials for our projects, it is still a bargain. So a shift in paradigm in our expectations of what we will have to spend to receive satisfaction is also in order. We cannot expect the manufacturers to keep the prices to us low while at the same time they are paying more. That is just an understanding of simple economics. I know that my prices will be going up!

Yours for a viable modeling future – Bob Hunt     

Alan Hahn

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Re: The paradigms, they are a changin' (With apologies to Bob Dylan...)
« Reply #1 on: February 14, 2008, 09:59:40 AM »
Well, I guess " the answer my friend, is blowin' in the wind, the answer is blowin' in the wind..."

Apologies to Bob D. too.

Offline Mark Scarborough

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Re: The paradigms, they are a changin' (With apologies to Bob Dylan...)
« Reply #2 on: February 14, 2008, 10:51:14 AM »
well spoken Bob, it does make a lot of sence,, and there are a BUNCH of those wind generators going up all over the NW, so I can see some of that causing the shortage, the sad part is that they probably throw the light stuff away as scrap! lol
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Offline Scott Jenkins

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Re: The paradigms, they are a changin' (With apologies to Bob Dylan...)
« Reply #3 on: February 14, 2008, 11:02:26 AM »
Take heart, I have planted some balsa seeds and yes they came up. I will let you know how they fair in a year or two. I live in Florida and from what I have read the climate here is not exactly like where most balsa wood comes from but very close. In south america it is considered a weed and they spread about the same coming up everywhere.

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m) During the refuelling and the restart of the motor, and until the time when he releases the model aircraft, the mechanic must keep the model aircraft in contact with the ground by at least one point and with the centre line outside the flight circle. During that time the pilot must be crouching or sitting inside the centre circle. He keeps one hand on the ground and his handle and his lines as close to the ground as defined by the F2C panel of judges until the model aircraft starts again.

Offline John Miller

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Re: The paradigms, they are a changin' (With apologies to Bob Dylan...)
« Reply #4 on: February 14, 2008, 11:31:37 AM »
I have to agree with Bob on this subject. One of my recent epiphanies in stunt design has to do with this very subject.

I realized that as a CAD drafter, I could make better use of the materials by using heavier, but thinner, balsa, and ply, for my assemblies. When utilized with the accuracy of laser cut parts, I could duplicate, or exceed the stregnth and remain near the same weight as if I was using lighter balsa.

I've been using 3/32" wood for fuselages for years, and experienced no problems compared to the previous light weight 1/8" parts. I'm about to try some 1/16" fuse sides on a future project.

Formed parts rather than blocks, is another possible use of heavier balsa. Such parts could be as light, or lighter, as strong, or stronger, than parts carved, shaped, and hollowed out of blocks. There will always be some parts that will have to be shaped from blocks, but I try to minimise them where ever I can.

I seldom use plywood doublers heavier than 1/32" . I use very little 1/8" ply anywhere. Instead I laminate 1/64" ply to 3/32" balsa for parts that, in my experience, are as good as 1/8" ply, without the weight, often 1/4 of the weight. Where I do use 1/8" is usually in the gear mounts. I might use it in the bellcrank mounts, but prefer Bass wood for that use.

My rib doublers for the gear support are 1/64" plywood laminated to the 1/16" ribs, both sides usually, and so far no gear failures.

Wing spars, 1/8" X 1/4" or 3/8"  set flat, to the outer surface of the rib, give me the best in stregnth for the least weight. For added stregnth, a strip of .007 carbon fiber laminated between the spar and the leading edge sheeting will take the spar's stregnth into unbelievable values compqared to wood alone.

These are just a few of the structural items that can be considered. The last several planes I've had laser cut have not been hand picked contest wood, rather run of the mill balsa.

When coupled with changes from traditional finishing, as well as power train items, it should be possible to easily use run of the mill balsa, and still keep the airframes light. Plus, there's always the high altitude solution, lighter wing loading by increasing area.

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Offline Leo Mehl

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Re: The paradigms, they are a changin' (With apologies to Bob Dylan...)
« Reply #5 on: February 15, 2008, 04:51:55 PM »
Bic Brennen uses light Baswoot for his formers on his take-apart Barnstormer and it is real light. I can see using 1/16" basewood for fuselege sides. and geodic the insides with 1/8" sticks plus plywood doublers. I have rarely used contest grade balsa. You just have to be selective. y1 y1

Offline Randy Powell

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Re: The paradigms, they are a changin' (With apologies to Bob Dylan...)
« Reply #6 on: February 15, 2008, 05:06:26 PM »
WEll, as I said elsewhere, this is the reason I build planes the way I do. Smaller dimensioned wood makes for a somewhat spidery stucture, but it has worked out well for me.
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Offline Bill Little

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Re: The paradigms, they are a changin' (With apologies to Bob Dylan...)
« Reply #7 on: February 16, 2008, 03:52:30 PM »
My first thought when I saw *(apologies to Bob Dylan)* was that we are "Caught in a Crossfire"  (I know, now I owe apologies to SRV), but Bob has some *ties* to that song........ ;D
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