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Spar Cap Material

Hello,

I am considering building a DA2B.

The viability of the project depends on the availability of spar cap angle extrusions. AND10133-2004, 2024-T351, 2" x 2" x 0.25".

I cannot find a supplier .... any suggestions ?   I am in Australia and have looked both in country here and also in the US.

Steve

Hi Steve,

I have located and recieved quotes from several suppliers here in the states. The material is not uncommon. The biggest problem is getting the material at the lengths called for in the plans. Standard length for extruded aluminum is 12ft the plans call for 14ft. Not hard to get but does require a lead time of several weeks and a tooling charge averaging around $750 US.

Another solution is to build with the folding wing option (drawings in files section of the Yahoo group). With the shorter lengths needed with the folding wing you could avoid the tooling fees.

Another good option is if we get some builders together for a group buy to spread the tooling fees among more builders. If anyone is interested in group buys for any materials I would be more than happy to facilitate.

Here is a link to the best pricing I have found yet.  http://www.aaaairsupport.com

Hope this helps,

Bryan

Hi Bryan,

Thanks for the quick reply. Any suggestions on specific suppliers who stock the 12 ft lengths ?

I will have a look at the folding wing drawings. That could be an option. Is that the folding wing design that was featured in Homebuilt Aircraft Magazine approx 30 years ago ?

My other thought is to check the stresses in the spars and see whether I can substitute 6061-T6, which is readily available in the required size and length (I can get 18 ft lengths).  No guarantees on this since I have not yet done any calcs but there is a chance this idea might work. Obviously not a substitution that should be made blindly without the appropriate engineering. I will run some preliminary calc's see if it is worth pursuing.

Steve

 

 

To follow up on my previous post:

A few pages of fairly rough calcs show that the stresses in the DA-2 spar are not excessively high and that 6061-T6 warrants further investigation as a potential spar cap material. I can get this is 18 ft lengths and it is much easier and cheaper to source than 2024-T3.

I really don't want to encourage people to make mods of this significance unless they know what they are doing so I won't go into any specific numbers. The yield strength of 6061-T6 is significantly less than that of 2024-T3 and so there would be a loss of reserve strength. But, to me, the question is not whether the modified aircraft is as strong as the original but whether the modified airframe is still strong enough to carry the flight and landing loads to which it will be exposed in service (I used FAR 23 for reference purposes).

Anyway some more work is required to provide a definitive answer. Whilst at it I might consider the wider question of whether the entire airframe could be built from 6061-T6 in lieu of 2024-T3.

 

Quote from tdfsks on May 13, 2018, 6:04 pm

Hi Bryan,

Thanks for the quick reply. Any suggestions on specific suppliers who stock the 12 ft lengths ?

I will have a look at the folding wing drawings. That could be an option. Is that the folding wing design that was featured in Homebuilt Aircraft Magazine approx 30 years ago ?

My other thought is to check the stresses in the spars and see whether I can substitute 6061-T6, which is readily available in the required size and length (I can get 18 ft lengths).  No guarantees on this since I have not yet done any calcs but there is a chance this idea might work. Obviously not a substitution that should be made blindly without the appropriate engineering. I will run some preliminary calc's see if it is worth pursuing.

Steve

 

 

Steve,

Here are a couple companies I have found located in California.

https://aircraftextrusion.com/      http://www.aaaairsupport.com/

I have found several others but not as easy to work with and higher pricing.  Both of these companies were more than happy to provide a quote and work with me.

As for 6061-T6, I would be VERY cautious making that kind of change. There is a huge difference in yield strength and tensile strength. Leeon designed for light weight and economy. There has not been a spar failure in any DA aircraft that I am aware of and would hate to see that change. The DA-2 has been flown regularly by some severely over gross without any known spar issues.

I can give one example of a change from 2024 to 6061.  The BD-4 changed the spar design from 2024 to 6061 and the increase in material thickness and weight was substantial.

I believe the plane you reference in the magazine article was a one off that used a different airfoil and some other mods. I would like to see his folding wing design. The design in the files section of the Yahoo group is based on the mustang II design and the gentleman that created the drawings also shows his math for the structural analysis he performed on the design.

It all boils down to this is experimental aviation. Have fun, experiment, but in the end be safe and don't take unnecessary chances.

Bryan

 

Hi Bryan,

Thanks for the links. I will follow up on these.

I will reply privately re material substitutions / spar mods.

I have downloaded the folding wing design from the yahoo group and will have a close look at this. I am very familiar with the MMI/II wing.

With regards to the Bill Turner folding wing (Homebuilt Aircraft Mag Feb 85), I have no info other than that magazine article. As featured in the article, the aircraft does not yet have a registration marking. Does anyone know if this still exists ?  Its rego or current owner ?

Steve