Wood Rotors

Tex~N~Oz

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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.
 
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I once heard a bloke [ old timer] say sumthn like, " woodn prop, woodn rotor, and woodn fly". ;)
 
I had a set of wooden rotors I flew years ago on a tow-glider. They worked well, but were very temperamental to moisture and heat, even though they were sealed. They were very fragile and hard not to mishandle and damage.

The main reason they are not used is because metal and composite blades are much more stable to outside weather conditions, and more resistant to damage.

Its like the horse and buggy, worked great for the times, but better things came along.
 
As I understand it, Cmdr. Ken Wallis is very partial toward wood blades. (of his own design and manufacture)
He has reasons that are very interesting! Perhaps Dennis is familiar with this?
These are all his and all have (I think) wood blades.
 

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As I understand it, Cmdr. Ken Wallis is very partial toward wood blades. (of his own design and manufacture)
He has reasons that are very interesting! Perhaps Dennis is familiar with this?
These are all his and all have (I think) wood blades.

I asked Ken about why he uses wood blades. He said, "it's hard to teach and old dog new tricks, I guess". He said that is what he knows how to build, he has everything set up that way to build them, and they work well for his purposes, and since he is not interested in selling them, there is no reason to change.

I said quite right, old boy.
 
Ok putting the fact we all like the Droagon wings, Sport copter blades, aside...

Is there really any reason for not using a wood blade i.e. are they dangerouse or no more dangerouse than the two put aside, as far as making them they do not seam to be too difficult to make and I am sure there are some difficulties but that is what everyone flew in the early years.

So from this point is there really any reason why other than economics or performamnce wood a wood blade be better in performance and more economical than alum or fibber.

Dan ( Ilike the idea of being able to make every part of my aircraft myslef )
 
Is there really any reason for not using a wood blade i.e. are they dangerouse or no more dangerouse than the two put aside, as far as making them they do not seam to be too difficult to make and I am sure there are some difficulties but that is what everyone flew in the early years.


No real reason not to make and use wooden rotorblades if you want to. Early helicopter blades were wooden, so were autogyro blades in days of old. So were the Air & Space blades. So are the Wallis blades.

If you build and fly them correctly, and apply proper care, they will be as safe as any blade. The best ones would be built off the latest Bensen plans. It could even be a fun project with rewards of great satisfaction of completion.
 
I not too sure of the facts but did hear from someone who should know, a lame friend, that the latest ELVIS heli, here in OZ are flying wooden rotors because they couldnt get the hours out of anything else, with the loads they are lifting?????
 
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?
 
If you have a prop blade let go, a wooden blade would be much more vulnerable to
catastrophic damage than an extruded one. cant speak for metal (dragon wing, etc)
but that, and efficency, made my mind up, ( after I saw a prop let go).
Wooden blades are great for gyrogliders, though.
 
You can swap from Bensen wooden rotors to RotorHawk extruded blades with no
alterations to the head other than the trim spring.
 
EI-GYRO, has a great point there. I see the vaule of your statement for the alum, I would then have to think that a prop blade strick to a fibber blade would be just as bad as wood.

What if the wood blade was covered with Kelvlar glass this would add to its strength and would also help seal and protech it from the elements.

What do you think about that.

Dan
 
Wood Rotors

Inside the 18A rotor - 12.5 inch chord - Spar is composed of 1/16 inch birch laminations, remainder is Sitka Spruce with a filler of Balsa wood. The wood is covered with epoxy filled fiberglass and has a stainless steel leading edge protective strip. Tip cover and retention plates are aluminum.
 

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I used to fly Bell 47's with wood blades - schools liked them because they had no hour limit & were strictly on condition. So if you took care of them the wood blades were potentially cheaper to operate - but utility operators all used metal blades.

The school ships were usually in hangars every night & rarely flew in crappy weather, not the case with everyone else - they really didn't like being exposed to the elements & didn't tolerate any abuse.

Dennis is spot on here - nothing wrong with them if you take care of them, but they do have their limitations.
 
I think the 18A blade is a lot more robust than a Bensen wood blade, which is largely
hollow. The part aft of the metal spar is not terribly strong, and the metal spar gives
no torsional strength. So if the rear half of the blade was substantially disrupted, it
would be bye-bye time.
They have a lot less inertia than extruded blades, so less float in the flare.
But they feel soft, and nice to fly.
 
For those of you that would like to know what I've posted about extruded aluminum blades, here is one of the posts:

Thread; Extruded Blades
04-11-2007, 09:17 AM
My only problem with aluminum extruded blades are that they are not a composited metal structure, besides the spar. Meaning, that like a Bensen or Rotordine blade, if a stress crack occurs, there is more than one layer of material that should hold the blade together until the next flight, where the crack should be discovered during inspection. If a crack would occur on an extruded blade, it is possible that it would crack all the way in one flight, not ever giving the pilot a chance to find it.

But..... I agree that if properly assembled the blades seem to be holding up to customer use. As Mike said, he has been using them for 9 years. How much flight time that translates into I have no idea. Even if it was hundreds of hours, thats nothing compared to the time as a fleet that we have put onto composited metal blades over the years.

To that end, I also use extruded aluminum blades on the UAV helicopters I build with great success, but limiting the life to 250 hours. I use the fully symmetrical 6.750" cord blade. I tried to buy they from Vortec, lucky I didn't send my money, ended up they didn't have any in stock and he would have kept my money until he received more orders so he could afford to extrude a new run, which turned out to be never.

So I had to have my own extrusion dies made, and I found a good place that could extrude short runs and had them made myself. Only cost around $14,000.00 for dies and all, including a run of blades, forward spar, middle spar and flat caps.

I'm looking into fiberglass "Pultruded" blades for my next project.
 
Factory Bensen wood rotors

Factory Bensen wood rotors

These photos were taken around 1966. These were my first rotors I ever purchased. They were factory built Bensen. I got into Army helicopter school shortly there after and never got to fly them. They sure were "pretty" !!!
 

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Chris, I still have an old set of wooden blades in my rafters in one of my other homes, painted white complete with nose weights & trim tabs. Don't know there history, but I did flyem once under power about 10ft off the hard deck over the runway just to see what they were like.........Dick
 
I'm looking into fiberglass "Pultruded" blades for my next project.


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
 
Ok, so you've established that wood rotors aren't absolutely the worst idea as they have been successfully flown in the past. There are several mentions of "limitations" but no one has really said what those limitations are.. It's been mentioned that they bleed off fairly quickly as they haven't the weight, but is that all? Any special mention to other problems noted in the past? I've never heard of them delaminating except for the one incident in the desert where it was very hot, but I'm sure that could be rectified with proper curing of the epoxy base.

Mr. Burgess - Those are some fine looking blades. They scream old school styling and I'm partial to that look myself. I bet a nicely built gyro with a nicely built wooden rotor would be an eye catcher for sure, especially if the machine was built along the same design. A mate of mine has a CNC router and I might look into making a prop to match..
A nicely polished brass leading edge on both.. Yeah..
 
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