plywood rotors

[Sonnyj]

Is anyone out there flying woodin rotors as a primary system.
Thanx Sonny

[Harry_S.]

Not here Sonny. The last ones I flew, ended up as kindling, :D


Cheers :)

[Aussie_Paul]

There is a set in Tasmania, on a direct drive VW Bensen gyro, that are flown on a regular basis by father and son team, Kieth Jamieson and his son Geoff. Geoff gained his gyro instructor rating a couple of years ago and has a Raf with one of our "Effective" stabs.

Geoff test flew the first Oz Butterfly for Greg Mitchell a few months ago. maybe greg could comment on the plywood blades of Keiths.

Aussie Paul. :)

[PeroxidePropuls]

I have a friend who is building one of these Vortech helicopters. He has built the rotor blades in something called glulam. It is not the same material as plywood, but close to it. The blades are solid wood glulam material. VERY light! -And cheap! My friend claim they are strong enough and he intend to fly himself with this machine, so I guess he is convinced about the quality. The guy is an aviation engineer and I find him to be a quite clever fellow.
Anyone in the forum that has heard about this material for rotorblades before?

Erik

[PW_Plack]

Perhaps it's short for "glued laminate?"

[PeroxidePropuls]

Perhaps it's short for "glued laminate?"
Yes, it is.

Erik

[Sonnyj]

Hello Erik
Thanx for the reply.
I have used glulam beams in home construction,they are stronger than solid wood beams inthat they are more flexable.
I don't see why it won't work very well,the tuff part is going to be getting the airfoil shape,but not imposable.
Please keep us posted on the progress,and the method of construction.
thanx Sonny

[Brent_Brown]

The 18A&S has wood core blades

[Sonnyj]

Hiya Brent
What is the 18A&S,Whats it coverd in,are there any flying?
Bythe way where is Linden? Just curiouse.
Thanx for the info Sonny

[spoke]

Sonnyj.. I fly woodin Bensen blades on a modified Bensen air frame and a Mac motor ,they give a very soft ride.. Art Stewart.

[Brent_Brown]

18 Air and Space it is the FAA certified gyro that that can do jump tackoffs. I don't have a pic but you can look it up or someone might post a pic here for you. Linden is off 401 north of Fayetteville

[Sonnyj]

Mornin Yall
Thank you for the info Brent,I have seen pics of the 18A&S but had no idea the blades were wood core. :o
Art I am rebuilding a modified Benson with a Mac motor.I am going to build the Monty Hoskin blades.I have a partial set of planes for the Benson blades and would like to build those if I could come up with a complete set of planes for them.I also have drawings on what looks to be a good aluminum blade,that I will try my hand at next year.
By the way Art,where are you located?
Have a nice day all Sonny :)

[spoke]

Hi Sonny j. I live in Fredericton New Brunswick Canada , I also have A set of Montys blade plans, I have another gyro with direct drive Sube andRotor Hawk blades 26ft flys very smooth best blades i have had, and ive had a few. we dont fly here in the winter its usually too cold.. all the best Art Stewart

[GyroRon]

Sorry to sound like a blaster, but I think you guys are nutz to fly wood blades and even more nutz to want to build a set. Why you would want to trust your life to a set of homemade pieces of wood and glue? I can see saving money by buying a older used gyro or a used engine and even used rotorblades, but this is one area I wouldn't skimp on. Again no offense meant, just my two cents.

[bowns]

Here are some pictures of homemade blades from my fellow.The blades are made of solid plank wood and are wraped aluminum skin.I think the blade may have some chordwise problems as well as a more flexible lifespan uncertainty.

photoes unable to be uploaded?

[bowns]

Here are some pictures of homemade blades from my fellow.[IMG]

[bowns]

Here are two others.[IMG]

[Sonnyj]

WOW,GYROS over China!!!!!
Thank you Bowns nice pics. :D
I am glade to see that I'm not the only one building home made rotors. :)
I realy like building things,it gives me a lot of pride in the accomplishment. :cool:
Thanx Sonny

[spoke]

Gyro Ron . I guess a lot of us are nuts But ask the chap who builds experemental aircraft if they trust wood wings. I also drive bikes but am too old for the dolls have a good day . Art Stewart

[GyroRon]

A wood wing on a airplane is not the same as a rotorblade Art!!!!

[Brian Jackson]

A wood wing on a airplane is not the same as a rotorblade Art!!!!
I second Ron's sentiment. Wings are forgiving if you're off by a few thou whereas blades are not. Both may share similar airfoils, but as you scale the profile down it becomes more "twichy" and prone to twisting. Think about it. The narrower a wing/blade, the weaker it becomes structurally, but more efficient aerodynamically.

I know nothing about wood blades of yesteryear, so I will watch this discussion with great interest. I'm ignorant of many facets, but trying to learn.

Thanks,
Brian Jackson

[bowns]

Thanks Sonnyj and Ron.
The pictures are posted not as a proven success.To me it's only a will to show.I wouldn't say i have much trust or faith in simple design like this.Aside from heavy stick control forces (i learn this from veteran posts and articles) that may occur,i see how much they twist in air flow.
I thought for a while to enforce a plank wood design with spring steel plate or strips,but found it hard to do so in a chambered airfoil--may be easier with a less efficient symmetrical like MR.Jukka Tervamaki did.
Guess the proper way to apply wood blades is a roof-high towing kite?

[Michael Stump]

Guys, most of the classic Bell 47 (M*A*S*H) helicopters use wooden blades. I've flown hundreds of hours on them and they are fine. Wood is beautiful in that it tends not to have the fatigue-cycle problems like metals do. You can also legally repair it easily, and repeatedly, even in certificated rotors! There is nothing wrong with wooden blades in general (Bensen offered them, but they weren't all that great given the technology and the era), but with more modern profiles and design enhancements, wood has certain advantages over metals and composites, such as ease of manufacture, and cost. On the other hand, wood blades tend to shake and seem to be in need of readjustment any time the humidity chages. It's tough to maintain an even moisture balance across a long wooden rotor system.

Each material has its pros and cons. Wood has been proven to work in aircraft since the Wright Bros., including many Certificated types....one caveat....proper engineering is an absolute must, especially in the area of balancing, flutter prevention/stiffness, etc. It's easy to do things dangerously wrong with this material.....

[C. Beaty]

We use wood propellers without a second thought.

The centrifugal force trying to fling a rotor or propeller apart varies as the square of the tip speed. Since typical propeller tip speed is about twice that of a rotor, the fling apart force for a propeller is about four times that of a rotor.

Yellow birch is the most appropriate wood for both propellers and rotor spars.

Here’s how it stacks up against 6061-T6 extrusions:

Material-------Density, lb/ft³----Tensile strength, lb/in²

6061-T6-------169----------------38,000 (Alcoa aluminum handbook)
birch------------43-----------------16,600 (Marks mechanical engineers handbook)

Aluminum is 3.9 times heavier than birch but only 2.3 times as strong.

On a specific strength basis, birch is 1.7 times stronger than 6061.

The strength listed for birch is for a short, straight grained sample. In actual use, birch must be laminated from strips glued together as a workaround against grain slope and other defects, making it not much better than aluminum.

Laminated birch has been widely used in the past for rotor blade spars; The Bell-47, Hiller UH-1, A&S 18A to name a few.

Wood doesn’t have the limited fatigue life of aluminum.

I have built rotors patterned after the Bell-47 construction method; lead bar at the leading edge for chordwise balance, laminated birch spar, vertical grain balsa afterbody and fiberglass cover. The B-47 used a steel bar as balance weight rather than lead.

To pick up the full strength of the spar requires increasing the spar width near the root and the use of 15-20 ¼” bolts.

Worked fine but very labor intensive as compared to bonded aluminum.

Attached is a spar section from one of my 3-blade rotors.

[skyguynca]

Thanks for the info, got any more pictures of your blades?

[C. Beaty]

Attached is a scan of one of the tips of the last 3-blade rotor. The dark area in front is a lead bar. Each tip had 10 lb. slugs, the intent being to have enough stored energy for jump takeoff.

I think this is a sample I made up to determine the influence of the tip weight on ¼ chord balance.

The actual lead slugs had 3 cast in holes for retention rods. The slugs were cast in plaster molds.

The balsa fillers for the rear portion were cut from planks with grain running vertically.

The airfoil was a Boeing VR-7 with reflex.

[skyguynca]

pretty impressive, how did it work?

[C. Beaty]

The rotorblades flew just fine. I never had sufficient power to overspeed the rotor enough for a jump. There’s a photo of the 3-blade gyro with the blades just pictured on post #99 of “Ideal gyro blade design” thread.

I also flew a wider chord version of these blades on a 2-blade rotor with collective pitch.

[Sonnyj]

Thank you Mr. Beaty,that's the kind of info I was looking for.
I do intend on a set of wood rotors for the little bird I got from Chuck Irby.
Thanx again Sonny

[skyguynca]

Attached is a scan of one of the tips of the last 3-blade rotor. The dark area in front is a lead bar. Each tip had 10 lb. slugs, the intent being to have enough stored energy for jump takeoff.

I think this is a sample I made up to determine the influence of the tip weight on ¼ chord balance.

The actual lead slugs had 3 cast in holes for retention rods. The slugs were cast in plaster molds.

The balsa fillers for the rear portion were cut from planks with grain running vertically.

The airfoil was a Boeing VR-7 with reflex.

Now in this thread you talked about building blades just before this post and of course this one. Did you use these blades just on your gyro? Or did you use it on the 3 bladed helicopter? Also what profile did you use on the helicopter if not this one?

Thanks for the info.

[C. Beaty]

The helicopter that was flown in 1976 used cut down ex-military OH-6 blades. OH-6 blades have a NACA-0015 airfoil and are fairly draggy. It is the same airfoil as used on the McCulloch J-2 gyro.

The Boeing VR-7 airfoil blades were 6” chord and were only flown on the 3-blade gyro.

The VR-7 airfoil is relatively modern, having been developed for the inner section (root to ~70% radius) of a heavy lift helicopter rotor. It is a better airfoil for gyro or helicopter.

[skyguynca]

Thanks for the info on the VR-7. I am guessing that it is really close to what Ernie is using for the Mosquito Rotor blades but reflexed to prevent the CP from moving much.

Chuck thanks for all the info, you see to be a bottomless well of great info on this stuff, you have the answers and thanks for sharing.

[C. Beaty]

The Mosquito Man’s name is John (Uptigrove) and he started out with Rotordyne blades.

I think he’s now using Ernie’s (Boyette) blades which are a mildly cambered and reflexed NACA 4 digit series, similar to a 2312 with reflex.

The VR-7 incorporated a reflexed TE tab from the beginning. That’s the rotor airfoil used on updated Boeing CH-47 Chinooks with tip airfoil being a VR-8.

[skyguynca]

Thanks Chuck, I had been looking for the info and use of th VR7&8 airfoil. What do you think of the older laminated marine plywood rotorblades with the steel spar strap and the solid spruce rotorblades??? Truely viable or just someone's whim they threw in the Choppy plans?

[quadrirotor]

Why not those one?

http://www.autogirosargentinos.com.ar/

[C. Beaty]

Almost any airfoil that can be imagined is listed on the University of Illinois web site:
http://www.ae.uiuc.edu/m-selig/ads/coord_database.html

The Boeing rotorcraft airfoils listed on that site have some small surface irregularities, however.

The Bensen plywood blade was fine if made according to plans but a little draggy compared to blades that don’t have external noseweights.

I don’t know enough about to Choppy blades to intelligently comment.

[davreich]

The departing PEDRO squadron in Thailand had Huskies that had counter rotating wooden main blades. (Picture is off the web)

[madron]

hallo, i am new here, so its my first post and my englisch isnt so good.

i am a student product designer in belguim, i experementing with the giroscopic effect and i would like to make a prototype of a gyrocopter/plane for my final exames, i have started my quest by building a working blade in wood, and today by making a new one in wood (scaled) i have don it, i know the most of you are verry familiar with the effect but for me its a new expericens, but one hour ago in a verry light wind, i started to turn the blade to check how my bearings where working and het just started to turn and verry fast, it whas the last what i expectide that it would do. i whas verry inpressed by the speed.

how its made:
the blades are hand made, by ambrading (dont know if this is the correct word) the dimensions are,

thickness: 1cm/0.39 inch
width: 7cm/2.76 inch
length: 60cm/23.64 inch

the totale blade diameter is 148cm/58.31 inch and the blade is starting on +- 33% of the total lengt of a wing. (because i read that there is the most of the drag)

if someone has remarks or advise please let me know, i am open for ideas. i am planing to make rotors with length of 5m/16.40416 feet long

tonight i wil make a post with picturers.

[Ga6riel]

madron
not sure the data from a model will be all that usefull, as the very low reynolds number of the model would make a marked difference. Some model gyros use rulers as rotor blades. There would be a qualitative effect rather than a quantative one.

[madron]

madron
not sure the data from a model will be all that usefull, as the very low reynolds number of the model would make a marked difference. Some model gyros use rulers as rotor blades. There would be a qualitative effect rather than a quantative one.

so in other words, the best thing to do is to check if there is a big difference between the smal design and the big one. hmm i wil make a biger one now and see again what happens.

i am just asking, i dont know if this is a stupid question but how can i callculate how many force of wind, my wooden rotor can handel, i want to predict when it could break. can someone help me.

greetz, madron

[dick]

I have a set in the rafters in my garage. Flew them once about 20 years ago put them away for the same reason Gyro Ron said. Still got them though, In good shape.