Did my first static tests for my rotors on what was meant to be a windy day. Not as windy as I would have liked. But the wood rotors go! No stick shake, we got gusts up to 15mph which lifted the nose wheel its probably about 12mph here. Stick has zero shake at this point but we'll see when airbourne and they have another 100rpm. Looking good so far. Hope your projects are all going well. Next step find somewhere to fly this glider then finish my powered machine.

cheers

Hey Cameron, please post some pictures of your wooden rotors!

Thanks
David

Hey having trouble attaching the picture showing a server error. I did attach a video which will be in the file attachment bit below the text. I can see how to embed a url of an imagine into the comment but not how to add a direct photo. Can I do this without attaching as a file below?

Cameron, scroll down the page (on PC) and click on choose file and then you can add a pic on your device

For a link to a pic, click on image or URL above this box

see how ya go... looking forward to pics

So, what sort of wood do you use Cam? Where do you get it? What glue etc etc???

Hi The blades are in this case all Hoop pine. Hoop pine wood spar and the ply is also hoop pine. I made these 30 years ago with another guy Ivan Baxter and I've just spend some time stripping back the paint and re-painting balancing span wise and chord wise. I have a couple of things to fix on the glider before its airworthy (just getting some AN bolts etc and not happy with the amount of side travel on the stick so going to modify that). The blades are glues and screwed into a 3mm steel spar. We used a glue from a prop maker Richard Sweetapple (can't remember what its called but I've also used epiglue - any marine glue for wood is acceptable. When you make the blades you have to splice the skins as the marine ply only comes in 8 ft lengths so we had off cuts to check the splice joints with, we tested these by bending around until destruction, we got better than 360 degrees before the wood snapped beside the glue joint so the glue joints are more robust than the wood and If I'm bending my blades greater than 360 degrees my problems are bigger than de-lamination.

Seems to have held up well as I checked them out after stripping the paint. I put as much stress on the trailing edge as I dare to see if the glue had gone off, no go I would have snapped the wood so seems to be holding up. They are 7 1/4 inch chord just under 22ft 21ft 6 I think from memory and they are very light 18.5kg, compared to my Gerry Goodwins which are from memory 23kg? miles lighter than the sky wheels. However because they have chord weights 25 ounces about 2 foot from the tip they fly with massive inertia. So landing they hang and hang and hang. Ivan and I are working currently on an n8h12 cross section design (Ivan has access to a 12ft x 5ft CNC mill) we can access birtch marine ply in 10ft lengths. So we plan to experiment making a set which will have far few peices leading edge, spar, bottom skin and pockets (basically ribs for the profile) will be cut out of ply with top skin being normal 3mm ply glued on that then cluster plate, chord weights etc. It will mean two passes top and bottom of the mill gluing and screwing the steel spar , adding the top skin then painting, balancing, chordwieghts etc. Sounds like a lot but these were not hard to build but had to be very precise and had many more steps. If we are successful and they work we will have a nice set of N8H12 rotors for a single seat machine that should cost us about $500 a set, I will test them at different weights and loading up etc on the gyro-glider. Once we are confident they will work we will release the CNC files for the blades so anyone else who wants to do so can get a set made. They'll need to tell the CNC people they are making wind turbine blades - true from a certain point of view. Anyway Ivan and I will make ourselves a couple of sets each if the first one works out. Probably sometime this year as Ivan is building his own home at the moment and doesn't have huge amounts of spare time. Will keep you guys updated on our progress.

That is awesome! Can not wait to see how it goes. I also have a 5x12 cnc router, love it. Thanks for the write up.

David

Have you had a chance to determine if they warp a bit in humid conditions? Is it enough to affect performance?

They don't generally but depending on how you build them and particularly seal them its possible. Ivan and I made 5 sets together, 3 of us were building gyros at the time, I test flew most of them because I was instructing in gyrogliders at the time. I had learnt to fly wood rotors on the gyroglider at Gafton with Terry Boatswain who'd built 14 sets on various machines over the years. We used 3 sets of wood rotors on their gliders over the years and the that was a very well used glider which was kept under a roof made between two hangers simply supported at either end. Rocks thrown up by the car would occasionally pepper the leading edge which would be repaired with car filler (the leading edge is basically a shape and not the structural element which is mainly the wood spar and steel spar glued and screwed to it). So any chance of warping had plenty of opportunities over the years. They were very stable. However one set Terry had made had warped badly after they were made. They had one blade with over 5 degrees of warp in it. When the older glider blades got too beaten up (they were pretty bad by the end) we retired them and tried to get the warped set going. We did everything to get those going and we did get them tracked with a combination of bending the straps (actually a very good method trim tabs suck they are easy to set up but get in the way and are easy to bend by accident) and trim tabs but the trim tabs only came in after a certain rpm and with 5 degrees of pitch on one rotor they were near impossible to hand wind. My blades had been in storage and unused for about 16 years - were made 30 years ago. They have not changed as far as I can tell. However I did have trim tabs on them and removed them in the restoration so I expect once I'm light on the wheels I will need to spend a couple of hours adjusting pitch until they are completely smooth. At least the balance seems good the stick has been rock solid (but haven't gotten them to full flying rpm yet) but ZERO stick shake so far.

One thing that can happen to new wood rotors is moisture in the wood over the first few hours can actually migrate to the tips because of the centrifugal forces so the advice is if they start to go out of balance it takes about 5 flying hours for them to stabilise so rebalance after 5 hours if needed. Mine didn't need this or Ivan's or any of the others I've flown but I've heard it can happen.

One of the things Ivan and I did was perhaps not necessary but it may have helped was to not build one blade bench to make one blade at a time but we thought it a better idea both for time and stability to have a double blade bench. So we could set up and glue each stage with both blades at the same time. So wood spar to bottom skin would be at the same time we'd set everything up mix the glue and layout both rotors at the same time. We figured if there were any changes in humidity etc it would happen in exactly the same conditions so you wouldn't have one blade laid up in 60% humidity and the other at 30% for example. Each of the glue joints on both blades happened in exactly the same conditions. This may have made zero difference but it seems at least one variable we could control for and of course as the glue needed to set over 12 hours+ it saved us heaps of time. Because we worked this way and together it took us about 20 hours labour to make each set. By the time we did the 5th set we were very efficient. So that was one of the best things we did. Working with another person greatly decreased the time taken much more than saying a set of blades would have taken 40 man hours if we'd not been working together.

Well you sure have a ton of real world experience on the.. i have never flown a set of wood rotors.
Aluminum and fiberglass only.
I seem to remember that one of the small trainer helis had wood rotors? Bell? Sikorsky? I can't recall.
Where are you located? Did I drive through there on my trip?
Muz, you know where I went...
What was that place where I rode in the MTO3 and did some whale watching.

Was Byron Bay, Queensland

Bell & Hiller had wood blades. The only difference between Hiller & bell was 6 inches cut off the tips for the Hiller set.


Bell had confidence in their new Bell 47 and had no worries supplying blades to Hiller.

In the 90s Dushack International got caught welding an extension on a Hiller blade spars to make 47 blades out of them...

Oops

Dushack was big into bogus parts

Hi Henry, a few helicopters had wood rotors Bell 47 had them the Kaman still has them, and a few others, I live in Toowoomba Queensland.

You must live somewhat close to Muz. Wife and I drove up from Sydney and spent 3 great days in Brisbane not too long ago!

Somewhere near Coffs Harbor from memory? You stayed at Sapphire Beach at one stage. It was just before you got to Brizzy...

Yes he's further North I'm about 1.5 hours drive West of Brisbane.

Oh I thought Muz was further north than me Coffs is not too far away either. just south

Damn I can never upload pics or vids here....

I met a great guy near Coffs Harbor and we went up in an MTO3 and flew the beach and did some whale watching at Byron Bay!

Benry, email me any pics you want placed and I will put them on for you.

If you place a link for a video in your posts, I will embed them for you.

Cameron is south west of me, but we are both in South west Queensland... probably 2 and a bit hours drive away

Hey Cameron, haven't heard about the blades in a while. How is the testing going?

David