It’s nice to see a new rotor manufacturer arrive on the scene. I always admire guys who have the courage to start an enterprise.
I like your tip balance-weight socket and the fact that you haven’t blindly followed the classic “half moon” tracking feature that is fundamentally in error as explained here:
The first person I know of who brought this error to light and explained that the half moon should be the other way up (as you have done) was Jean Claude Debreyer, if you got the idea from him it would be nice to give him a credit, if you worked it out for yourself, bravo.
Looking at your design you have a 2.375” radius, assuming a 20 TPI thread on your adjusting screw that means that a 5° rotation of your screw would give about 1’ of tracking change (one blade increases by a minute and the other decreases by a minute). Using a modern dynamic balancer you can see the tracking effect of a 1’ change so ideally your adjustment system needs to be able to consistently and repeatedly change blade pitch by increments of 1’. I assume you’re using socket head screws (grub screws) to tilt the hub bar, I have a similar setup on my rotor for chordwise shift and it’s very difficult to achieve the accuracy required due to things like the play between your Allen key and the socket head and the tolerances in the threads themselves.
If my thread did have some influence on your design it’s a pity you didn’t talk to me before cutting metal because I have since developed for another manufacturer an easier, more accurate and cheaper method of adjusting tracking without causing a chordwise shift.
Also you don’t appear to have added any sort of scales to allow the operator to see how much he has changed pitch or chord shift, from experience, when dynamically balancing, this is a valuable feature that is missed by all the manufacturers of the rotors I have seen. In fact I don’t see how you are adjusting the chordwise balance, maybe I missed something.
Personally I don’t like the idea of those two threaded holes in the centre of the hub bar. Threads are stress raisers and you have them at probably the most sensitive part of the hub bar. I assume you’ve carried out an FEA study to satisfy yourself that you have a healthy safety factor in there.
Well done for trying, I wish you success.
The AutoGyro rotorheads are very similar to those from ELA. The solution given by Magni is original and different. Chordwise adjustments are possible (if I remember correctly, that was a modification done after a suggestion from Mike Goodrich...) and tracking adjustments are just not possible. The people at Magni probably consider tracking adjustments as unnecessary...Wait, didn't AutoGyro study Magni who bought the technology from Tervamaki who was influenced by Bensen who studied WWII German autogyros and flew Pitcairn autogyros which were licensed by autogiro inventor Juan de la Cierva ???
Yep, Denis you blatant copy-cat, you...…..
As Brian implied, it would be very difficult, even impossible, to create a 2-bladed autogyro teeter rotor that didn’t have design features “borrowed from others”. I’d even say that it would be pretty stupid not to look at what others had done and “borrow” the best parts that had been proven over time.
You also reply that:
To control costs, I feel that it is not necessary to include features that the vast majority of the customers will never use.
Yet you include a more expensive and complicated system for tracking, I could ask how many customers will know how to track your rotors?.
It’s clear that you want to be the “original thinker” and that my posts annoy you so from now on I’ll leave you (and everyone else on this forum) alone. This thread reminds me of the reason I stopped posting on this forum a year or two ago when I wrote
“You can lead a donkey to water but you can’t make him drink”.
Nothing has changed.
A small correction, AutoGyro copied the ELA (some say they even got a copy of all the drawings) and contrary to what many say, ELA didn’t copy the Magni, they introduced a number of new features and ideas (not all good in my opinion but they were at least different) and many of these features have been carried over into other makes.
AutoGyro rotor heads were identical to ELA (because they were copied), they have some different features now. The Magni solution is the one they purchased from Tervamaki (as Brian says). The original Tervamaki design didn’t have a chordwise or tracking adjustment and I believe the very early Magnis didn’t either. I had one of the early M16s and that had the chordwise adjustment screw that was designed and developed by Magni not me. Since September 2018 Magni rotors have a tracking adjustment feature and I was involved in the design of that.
Thanks for the confidence; as I said last year, it’s a waste of time posting here. You have my number if you need me.
How's the Magni tracking work Mike?
A good question, that... Mi Magni M24 was built in the first months of 2019, and the rotor head doesn't seem to have any... It has only the chordwise adjustment screw.
I e-mailed the Magni agent here, asking that, and he has just answered: there's no tracking adjustment in the Magni rotorhead. He says, however, that tightening the screws of the teeter block may work, to a point...
DW rotors are sufficiently uniform that a simple “stringing” before installation is all that is necessary to center the chordwise CG.This talk of chordwise adjustment makes me question what I thought I understood of the RFD (dang, hope I got THAT attribution right...) "slider" design. If I understood correctly, the blade assembly is allowed to find its own center, so "adjustment" was not necessary. Anyone able to confirm/clarify how the "slider" (mentioned also by Chuck B.) works?