Wood Rotors

Dennis, a couple of questions;

~ Are you planning to use purchased pultruded structural shapes or pultrude your own spar etc?

~ Why do you prefer fiberglass over carbon?

Dave

Hi Dave, I am working on something, but not yet convinced the market would be large enough to merit the investment. I have rarely ever seen anything that already exists on the market that is suitable for any of my applications. I always find it necessary to have the item custom made to my specifications.

It's not that I prefer fiberglass over carbon fiber. It's that I use whatever material is required to perform the task. If fiberglass is up to the task, then all the better. It's much less expensive and much easier to cut and work with. Fiberglass also has better frequency dampening characteristics over carbon. But, if carbon fiber is required to obtain the strength and rigidity necessary to achieve the requirement of the item, then I will use carbon fiber without hesitation.
 
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I have a shop full of shapers, planers, saws, etc.. etc.. that's just sitting there as I don't do woodworking anymore (or don't have any new projects to work on is more like it). I was thinking why not put them to good use?? Can anyone send me the plans for the Bensen blades? Does this require a whole different setup for the rotor head?

When you come past the Bay, and stop over for a cuppa, I'll give you a set of Bensen wooden blades plans, and the building instructions. You can go and have a ball building a set. If you want them earlier, send me a PM with your e-mail, I'll send the fullsized scanned ones.

Minnesota Mike, did you put the complete Bensen set I sent you on Gyro Wiki? Or is it on the PRA site? Tex-n-Oz, you might find them there there to download.

Saw a wooden Bensen set years ago, pretty things they were. Just imagine a varnished and polished set, just like the old Riva wooden boat hulls !! Man, I would give my left nut to have such a hull, with all the chromework to suit, and be cruising some waterway !! I believe Chris Craft had some copies of the Riva as well.

Francois
 
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Has anyone here considered flying rotors made of wood?? I know it used to be the done thing, but for some reason or another, it's no longer done. Can anyone tell me why? I know some of the most successful and safe aircraft have been wooden in structure and cannot imagine why a rotor system wouldn't be just as safe.

UPDATE.... I just found a previous thread I missed on earlier searches..
If I were only smart enough to know how to delete this thread you wouldn't be here looking at it now.


Excuse my intrusion, having read your bio I wonder what makes you ask this question..? Considering the new age passengers aircrafts using more composite than ever before why would someone like to have old fashion flappers on their crafts. I believe in the technological advancement of height tensile and malleable materials.

raton
 
Excuse my intrusion, having read your bio I wonder what makes you ask this question..? Considering the new age passengers aircrafts using more composite than ever before why would someone like to have old fashion flappers on their crafts. I believe in the technological advancement of height tensile and malleable materials.

raton

Don't get me wrong, but technology has it's limits and I'm still not sold on composite materials 100%. Wood, the old school material, is really good stuff for a lot of reasons.. It's strength is way up there with some alloys, it's flexible, when it starts to fail it generally gives you a lot of notice and generally doesn't do so immediately.
To this day I still get a lot of specifications for good ole fashioned wood, especially marine plywood, where composites just don't have the strenght/weight/flexibility/life requirements that wood does.
A few years ago I pulled some marine plywood out of a cooling tower that was over 50 years old and a cross-section cut of the wood looked perfect past the surface area. This 1" piece of wood, along with 4 others was used to hold up a 100hp motor/gear box that weight several hundred pounds, these boards spent their lives under water that was chemically treated with some pretty harsh chemicals and supported the torque and vibration of a big turning fan.
I'm not saying wood is perfect for everything, but I'll not call it the "old has been" of modern structural materials. It's just the one that's been around the longest. With all of that in mind, it's easy to wonder if it wouldn't make a good rotor as well. I'm definitely not going to discount it as a possible material to use. I just have to make sure what I build, if I choose so, is of the right design and specifications.
I've been around engineering long enough to know that a LOT of what you see in composites is nothing more than marketing. I've seen some really amazing composite materials misused to the point of being dangerous. Like Dennis says, it's all about what you are wanting it to do and the right application.
In aviation, you'll find that the materials of choice are chosen based on their weight and not necessarily longevity of use.
 
....why would someone like to have old fashion flappers on their crafts.....

The same reason some people restore old cars!! They are good to have. They still drive around OK, so why not fly old style rotors.

Using your logic, should we ground all Tiger Moth's, and change the wooden structure to composite ???

Francois
 
MADE IN CHINA ROROR ,Everyone to see, how?

MADE IN CHINA ROROR ,Everyone to see, how?

MADE IN CHINA ROROR ,Everyone to see, how?
 

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Don't get me wrong, but technology has it's limits and I'm still not sold on composite materials 100%. Wood, the old school material, is really good stuff for a lot of reasons.. It's strength is way up there with some alloys, it's flexible, when it starts to fail it generally gives you a lot of notice and generally doesn't do so immediately.
To this day I still get a lot of specifications for good ole fashioned wood, especially marine plywood, where composites just don't have the strenght/weight/flexibility/life requirements that wood does.
A few years ago I pulled some marine plywood out of a cooling tower that was over 50 years old and a cross-section cut of the wood looked perfect past the surface area. This 1" piece of wood, along with 4 others was used to hold up a 100hp motor/gear box that weight several hundred pounds, these boards spent their lives under water that was chemically treated with some pretty harsh chemicals and supported the torque and vibration of a big turning fan.
I'm not saying wood is perfect for everything, but I'll not call it the "old has been" of modern structural materials. It's just the one that's been around the longest. With all of that in mind, it's easy to wonder if it wouldn't make a good rotor as well. I'm definitely not going to discount it as a possible material to use. I just have to make sure what I build, if I choose so, is of the right design and specifications.
I've been around engineering long enough to know that a LOT of what you see in composites is nothing more than marketing. I've seen some really amazing composite materials misused to the point of being dangerous. Like Dennis says, it's all about what you are wanting it to do and the right application.
In aviation, you'll find that the materials of choice are chosen based on their weight and not necessarily longevity of use.

Thanks, I know what you mean.
raton
 
A couple years ago, I saw an old Vancraft ad promoting Chuck Vanek's wood blade kits. He hand-selected 11-foot spruce planks and IIRC, a kit with the boards, external tip weights and the steel spars in a kit were $29.95. If you wanted the boards pre-shaped with the airfoil, the kit was $49.95.

It's fun to look back on those (late 1950s) days, but the big issue today would be where to find acceptable wood stock. Every place I go seems to have warped, knot-filled, banged up lumber.

Kevin Richey once told me he was intrigued by the idea of extruded plastic blades with a metal spar. Any thoughts?
 
Dennis & I both listed some of the limitations of wood blades, for a weekend toy most of them wouldn't be a big deal. They just need more care compared to the alternatives.

Paul is also correct, quality wood is harder to find these days & not cheap either!
 
This is how it was done in '31



Why this is built up construction; 'D' box leading edge, and bulit-up ribs aft of the spar. I think there's an aluminium tube through the ribs too??

Please can anyone with some knowledge of wooden blades explain if this formative method of constuction was flawed? And how does it differ from the Bensen modernday versions?
 
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Just to help make the point that you use the right material to accomplish the job, I'll post this;

I have these rotorblades extruded for my UAV projects. It's basically a copy of the FLECK extruded blades that Vortech got a hold of. Since I couldn't buy them from Vortech (because they didn't have any in stock and just wanted my money to hold onto until the day maybe came where they got enough orders together to order a run) It was safer just to have my own die made and have them extruded. I did make some changes to improve the airfoil.

On a UAV helicopter, they work very well and are affordable to manufacture. I could have made these from expensive composites with hundreds of hours of labor.... but for the application, this was good enough. For the two-bladed UAV, the blades attached solid to the cone using an extruded plate with one flat side on the top and bottom of the airfoil, but for the latest fully articulated heads, I designed an extrusion for the blade mount that allowed lead-lag, as the attached print shows. Also notice the special aerodynamic tip I designed that reduces tip drag and noise.

But, as I said before, they are not a composited structure and if they started to stress crack, there is nothing to stop the crack. It can fail even in one flight if it started to crack, like any extruded blade can do. But hell, it's just a UAV paid for with free money, so go ahead and crunch them, we'll build more!!

I would really worry about solid extruded blades without a bonded in spar.
 

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A couple years ago, I saw an old Vancraft ad promoting Chuck Vanek's wood blade kits. He hand-selected 11-foot spruce planks and IIRC, a kit with the boards, external tip weights and the steel spars in a kit were $29.95. If you wanted the boards pre-shaped with the airfoil, the kit was $49.95.

It's fun to look back on those (late 1950s) days, but the big issue today would be where to find acceptable wood stock. Every place I go seems to have warped, knot-filled, banged up lumber.

Kevin Richey once told me he was intrigued by the idea of extruded plastic blades with a metal spar. Any thoughts?

Hi Paul: I've never heard of extruded plastic blades with a metal spar...let alone being intrigued with the idea.

But, I was, and still am, interested in wooden ones, enough to have bought Monte Hoskin's wooden rotorblade plans several years ago. Anyone know if they are the same as the Bensen wooden blade plans?

Last I heard of Monte, he was living in central Utah...

Possibly another local PRA chapter member was someone with whom you spoke with about extruded plastic blades with a metal spar??

RE: Your chapter rotorcraft event in June. If I can get the gyro changed over from the Rotax 503 to the Yamaha Genesis engine Racer is preparing, and have the required hours flown off in time, then it looks like I'll be able to make it. I doubt the 503 will enough uumph to handle the density altitude otherwise.
 
Apologies, Kevin! I thought it was you who'd talked of inexpensive plastic blades for training.

We'd love to see you here in June! But you're right...a 503 wouldn't cut it here for anyone bigger than a Jonas Brother.

Stay in touch!
 
Apologies, Kevin! I thought it was you who'd talked of inexpensive plastic blades for training.

We'd love to see you here in June! But you're right...a 503 wouldn't cut it here for anyone bigger than a Jonas Brother.

Stay in touch!

I was considering wood blades for inexpensiveness of training for those in the chapter who couldn't afford the current rotorblades that are on the market...

What is a Jonas Brother?
 
I have acquired a set of the Bensen plans from a member (you know who you are and thank you very much). It gives most of the information, but not all. Like wood types, etc.. Can other species of wood be used in place of the exotics? I'm surounded by hardwood but some of these pines I've heard mentioned will be hard to get here.
 
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