Ken Wallis Wooden Rotor Blade Construction Revealed

okikuma

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Finally, the secrets of how Ken Wallis manufactured his wooden rotor blades have been revealed in an old 31 March 1966 article in FLIGHT International magazine. The following link was previously posted by Kolibri282 (Juergen) under the Builders Thread of this forum.

http://www.rotaryforum.com/forum/showthread.php?t=23862

I know there's been previously much discussion pro and con on building wooden rotor blades, and the construction methods used.

In the article Flight International article, it explains the materials and processes use to build the rotor blades. What is interesting is that all the materials used were of 1930 - 1940s technology. I should also add, well documanted and proven technology.

To quickly summarize, first a .125 inch birch ply skin is laid. Then a strip of Ultra High Tensile (UHT) strength steel is glued to the plywood skin with Aerodux 185 resorcinol-phenol-formaldehyde resin adhesive. Then multi layers of Hydulignum (a Horden-Richmond Aircraft Company product of heat pressed thermoplastic resin laden plywood that was used to make propeller blades for British Aircraft during World War Two) laminates that are laid up to form the "D" structure spar, followed by one more layer of .125 inch birch ply skin. The outside of the blade is then covered with Madapolam, a cotton linen fabric and aircraft grade dope is used to glue down and seal the Madapolam. The following is a cross section of one of Ken Wallis wooden blades.

http://i289.photobucket.com/albums/ll224/my-pics-are-here/wallisblade.jpg

It is to my understanding that the wooden rotor blades on the WA-116 gyroplane "Zeus III" that Ken Wallis often seen flying in were manufactured by him well over 30 years ago! Now that is unlimited life rotor blades!

Wayne
 

Doug Riley

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Quite similar to Bensen's wooden rotor design. Differences in the Bensen design are (1) the steel-strip spar is on the outside, the bottom skin being tapered to butt against it; (2) Bensen did not specify fabric covering; (3) Bensen used a D-shaped pine leading edge strip instead of carrying the plywood spar all the way forward. #3 is probably a consequence of #2, since the exposed grain of a plywood leading edge would be difficult to make smooth without the fabric.
 

okikuma

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Hi Doug,

It makes sense to me that the fabric covering applied to the Wallis blades were to prevent delamination, moisture being obsorbed, and as you said, to smooth the surface of the blade.

Ken Wallis just understood the proper usage of each piece of technology to build a simple and effective rotor blade that he still flies with after all these years.

Wayne
 

StanFoster

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Kens work is very impressive. Thanks Okikuma amd Doug for your inputs. I work with wood all the time, but this area of study is new to me. Stan
 

skypuppy

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All Barnett J4B2 construction plans include instructions for manufacturing wood rotor blades. I think that they fly better than metal blades.
 

phantom

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wood blades

wood blades

I have built many wood rotor blades and I won't say that they fly better than metel blades, the thing that I didn't like was I would have a smooth running rotor and if I let the machine sit for a week it was no longer smooth I had to spend time to keep it right, with metel blades when they are set up they stay that way. with bensen aluminum I would find that ice would sometimes get inside through the gaps in the top but the fix was simply take them in to thaw out and everything would be smooth .I think the fabric cover on wallis blade may have helped to weatherproof them.
 

danmcgee

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I second Terry's guestion are the a downloadable set of the J4B2 construction plans somewere, I have now about 4 diferent sets of plans for blades and almost every type of gyro plans made that I know of in my library this would be an excellent addition.

Dan
 

skypuppy

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Barnett Plans

Barnett Plans

I am not aware of any downloadable plans for the Barnetts.
 

danmcgee

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Is there a set out there that anyone would want to sell or a set that I could image into a PDF to add to my library, as a digital form it is very easy to replace what in paper form is not so easy to replace is a mishap should happen.

Never hurts to ask.
 

kolibri282

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Wayne wrote:
Then a strip of Ultra High Tensile (UHT) strength steel is glued to the plywood skin with Aerodux 185 resorcinol-phenol-formaldehyde resin adhesive. Then multi layers of Hydulignum (a Horden-Richmond Aircraft Company product of heat pressed thermoplastic resin laden plywood that was used to make propeller blades for British Aircraft during World War Two)


Some questions concerning the Wallis blades:
- Does anyone know if the materials mentioned in the article, Aerodux 185 glue, Hydulignum and cotton, are still availabel/used today?
- Does anyone have experience with Aerodux glue, e.g. what temperature should be used to cure it, how long will it cure etc....
- What would be a replacement for the glue, the Hydulignum or the covering fabric?

Cheers,

Juergen
 
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okikuma

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Frohliche Weihnachten Jeurgen,

For what I can find, DAP Weldwood is an equivalent here in the US for resorcinol-phenol-formaldehyde resin adhesive. With a little research, I bet we can find a modern equivalent besides DAP Weldwood.

For Hydulignum, I have no idea. Perhaps someone could chime in and let us know. I'm curious myself.

As for the Madapolam cotton fabric. Here in the US, there's Aircraft Grade A Cotton fabric for aircraft covering. Of course, Ceconite and like synthetic aircraft coverings have replaced the good old Grade A Cotton.

Wayne
 

kolibri282

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Froehliche Weihnachten Wayne!
Thanks to you and Karl for the links and hints. So far I have tried to get to grips with rotorcraft theory but will start to build a 1:5 rotor shortly (about 8 feet diameter) to see if my figures are anywhere near the physics valid in this part of the universe.....;-)
Meanwhile I try to collect all the information I need for the day when scale goes up to M 1:1

Einen Guten Rutsch!
(thats Happy New Year! in German but Rutsch is probably from the jiddish word rosch meaning Anfang (=Start) )


Cheers,


Juergen
 

okikuma

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Danke sehar Juergen, Einen guten rutsch ins neue Jahr.

If I could find a source for Hydulignum here in the USA, I'd might try my hand at building and experimenting with a set of blades like the Wallis.

By the way, do you have any drawings for the Kolibri 282 rotor blades? I've been curious how those specific rotor blades were built.

Thanks,

Wayne
 

kolibri282

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Wayne,

unfortunately I have no drawings of the 282 blades. Pictures clearly show that they were built with a tubular mainspar like probably all
contemporary rotors. (In the book "Rotorcraft of the Third Reich" by Ryszard Wittkowski there is a picture of a 282 after an accident.
The ribs and covering have been destroyed so that you can see that the tube runs all the way to the tip of the rotor). The book
"Die Deutschen Flugzeuge 1933-1945" states that the 282 rotor had tubular spar and was covered completely with plywood which
in turn was covered by a layer of fabric. That's all I have on the 282 rotor.

I have some information on the blades of the Fa330 Bachstelze (there is a thread on that aircraft currently) which
also have a tubular spar. Of these I have some detail drawings which I could scan for you. Give me some e-mail
address to send them to if you think they might help.

If you are able to find a suitable material and experiment with Wallis like blades I'd be very curious to hear about your experiences.
The blades I have in mind are somewhat uncommon. There is definitely nothing like that on the market so I will have to build from
scratch and so far wood seems to be by far the best material (for once it has a low shear modulus in two directions and
therefore wood blades have a low torsional stiffness).


Cheers,

Juergen



PS: To anybody who read the answer I posted previously: Sorry, posted to the wrong thread...;-(
 
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okikuma

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Hi Juergen,

I kind of figured that the Kolibri 282 rotor blades were built up in the traditional manner like most rotorcraft during that time period.

I would like to see either one restored to flying condition or a flying replica built.

Thanks for your input Juergen,

Wayne
 

jehicks87

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hey all! I know its been asked a thousand times, but are there any places i can download or purchase actual construction plans for wallis or bensen blades?

Danke sehr!
 

curtisscholl

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hey all! I know its been asked a thousand times, but are there any places i can download or purchase actual construction plans for wallis or bensen blades?

Danke sehr!

I contacted the Wallis Estate. There are no plans There are no avenues to download or buy the Wallis blade plans. WCdr Wallis wanted it that way. He did not want to be responsible for someone to die for not following plans to the letter.

Bensen wood blade plans are on the PRA web site.

Curtis Scholl
 
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