Weird rotors

[Negative Attack]

Hi, this is my first post.

 

I have to apologise for not reading everything in the Autogyro section first - & I know that I'm going to use the wrong terminology for nearly everything... Sorry.

 

I owned a kind of autogyro model kite when I was 10 - it was a lot of fun - it may still be hanging up where I left it in the telephone wires. I did a lot of general aeromodelling & design until exams and life got in the way.

 

Since then I've made various rough & ready magnus/flettner kites with varying degrees of success. Mainly for lift @ minimum complexity, but also with an eye on maximum stability for a hands-off kite-driven boat.

 

The main reason I didn't get around to rotating blades is that I doubt that rough & ready would be good enough, not to mention the multiple hinges (or elastomers) needed to cope with buffeting?

 

Anyway, to cut to the chase, I have various crazy ideas - the problem with the Internet is that it's really, really poor at listing failures - especially in the more 'exotic' areas of engineering.

 

For now I'm asking #1 - if anyone has tried autorotating a ringed rotor? Possibly made from thin metal with 5-10% foam aerofoils stuck (under) flat metal blades?

 

And #2 - if existing concentric twin rotors are sort of like a biplane, then are triplanes, even quads feasible? & could those multi-'wings' also be fixed in a matrix of 3, 4 or more?

 

If any of these gets too heavy for a kite, I'd still be interested in bolting them to a mast and sailing it.

 

I hope this isn't all schoolboy errors.

 

Regards.

[Paul De Tourtoulon]

Welcome aboard, I have suffered from the autogyro illness the only thing that i learnt was light is right, weighted and heavy blades don't

fly nor do helicopter blades also  3 flights  = 1 broken blade, My first one was when I printed around 100 pages on them and built my own twin bladed

aluminium flapping head and I actually got it right first time, my last one is a twin rotor lightweight electric Rotor Rutter ( or something like that ).

 

 in between was a miserable lot of un flyable rubbish.🤐

[Trevor]

By ‘a ringed rotor’ do you mean that the blade tips are joined together with a ring? If so, I imagine this could be problematic since the blades need to rise and fall individually as they sweep forward (leading) and back (lagging). No doubt Rich H. will be along later to give you a more authoritative answer.

 

Good luck with your project. 

Edited July 21, 2022 by Trevor

[Negative Attack]

Hi Paul, thanks for being my first reply - in a weird way it's comforting to know that very few designs fly first time - I guess that means everyone still knows 100 times more than me but maybe not 1000 times more? 

 

I'm very interested in your DIY rotor head design - can you give me the thread title so i can find & view it?

 

Thanks & Regards.

[Negative Attack]

Hi Trevor, thanks for being my 2nd reply - you got exactly what I meant by a ring rotor (if there's a better handle I need to know it) - I've seen them on drones - I'm mainly interested in the finger-safety aspect, (hand-safety on the larger models) but maybe you get less broken blades too? (OTOH maybe slightly fewer but much bigger bills?)

 

I realise that letting the individual blades do their own "thing" reduces stresses in long blades, and there's a weight penalty from the ring itself. I suppose a light ring might need to be too strong to absorb those stresses without ending up too heavy.

 

The other problem of what is effectively a solid fan (apart from does the ugly thing work at all) - is will it lose efficiency from not letting the blades find their own optimum path?

 

Weight AND inefficiency would definitely make it an unlikely choice - except for an autogyro yacht maybe - (that's one of my many enthusiasms in this area - the possibility of a passively self-setting rig without a tailplane is almost magic).

 

Thanks & Regards.

 

 

[Richard Harris]

NA,

 

Interesting reading that you have had several Auto Kites, not the easiest flying machine to master.  I was recently approached by Richard Hammond to design something for an Amazon programme, they had seen the Panther thread on this very forum and liked the model. They wanted me to construct one that looked like it had been built on a desert island from ship wrecked parts and be be able to tow it down a beach, after much debate I persuaded them a Gyro Kite would be the easiest route as some form of Radio gear would be needed (and a competent pilot).

It took a while to perfect, if your interested I can post photos of the finished model? despite my comprehensive  ' how to launch and fly the kite' they clearly took no notice and it lasted all of a few seconds.

 

Here is the trailer to the programme, basically they are trying to get off the island and make several different contraptions in their attempt:

 

 As for a ringed rotor system, as Trevor suggests I don't think it would be any good a single bladed rotor as they need to flap up and down.

I am sure it would possibly work for a double rotor like the DB autogyro or the Twirl, there is only one way to find out for sure though. As for metal blades, I think that would be a no no purely from a safety aspect.

As long as the rigid type rotors are used in even numbers multiples should  work, have you seen Al Foots quadratwirl? flies exceptionally well.

 

Rich

 

 

[Paul De Tourtoulon]

On 23/07/2022 at 01:26, Negative Attack said:

Hi Paul, thanks for being my first reply - in a weird way it's comforting to know that very few designs fly first time - I guess that means everyone still knows 100 times more than me but maybe not 1000 times more? 

 

I'm very interested in your DIY rotor head design - can you give me the thread title so i can find & view it?

 

Thanks & Regards.

Sorry but that was around 25 years ago all been binned a long time ago.

 all I can find is this,, I probably have a video on dailymotion but I can't access it under paulinfrance.

 

 I remember is that as the coning angle increases ( blade going forwards )the blade angle decreases I think around a maximum of 3°.

Edited July 26, 2022 by Paul De Tourtoulon
coning angle

[Richard Harris]

Looks interesting Paul, your OD?

[Paul De Tourtoulon]

Yes all my OD's have flown with home made blades to boot, only one of my autogyros didn't fly and that was a plan, it crashed a lot.

Edited July 31, 2022 by Paul De Tourtoulon

[Negative Attack]

Hi Rich - thanks very much for replying - so many insights too.

I think your 'shipwrecked' gyro kite would be right up my street - I would love to see the photos - I'm extra interested in the improvisation aspect - my absolute favourite programme was Scrapheap Challenge - I'm still living that dream.

 

It is a great loss that viewers didn't see a home-made gyro-kite performing properly - but however it ended it was a noble attempt to inform and inspire new generations of modellers - not to mention lapsed ones like me.

Mr Hammond was a big part of Top Gear and his physical courage is beyond question - but a lot of those viewers (a vulgar fraction?) tuned in to to see bad ideas (& a few good ones) crash & burn. I'm not surprised a similar themed programme (especially non-BBC) would be far too happy to negligently crash your kite for a similar audience. 

Basically, good engineering  working successfully doesn't impress the human LCD - it's always trumped by a crash. 

Ho Hum...

 

But it's particularly kind of you to assume my attempts at the Magnus effect were successful - I can't take any credit for the toy version I lost - it was widely sold into the '60s.  

My first rotor craft build was a Meccano trolley (paperback-sized) driven by an anemometer mill made of ~40 cups cut from eggboxes.  I was still in primary school for that one but I knew a low enough  gear ratio would allow it to crawl into the wind, and it did.

A few years ago (seduced by tales of almost vertical lift and massive stability) I built an EPS Savonius kite off youtube, less than 30cm so I wasn't expecting much - but it barely managed to lift its own tether in a medium breeze - also unstable in stronger gusts. I thought EPS coffee cups as flettners either side might fix both issues but if anything made it worse. I got a weird feeling that Magnus scaling was too much against me, so I went back to the comfort of proper aerofoils.

 

Autogyros are gaining interest despite their baffling gyro physics - but I can still only find maybe 10% that's kite related.

There seems to be even less on eg. autogyro land yacht models. I think building the latter would teach me a lot - but don't hold your breath - I haven't yet found a design to steal from, and the Moore-Brabazon boat stuff is very sketchy about tacking. Maybe it's nearly impossible and I should try a land-proa?

My main reason for wanting to try ringed rotors was actually safety - if it worked I would keep the option of slowing the rotor with a glove.

 

You're spot on what I need with the Quadratwirl - it's solid rotors wouldn't be actually ruined by rings, and they fly it despite its rotor efficiency at 1m dia. doing it no favours. I'm still getting my head around it but I am worried the wings are doing a lot of heavy lifting while the less-than-optimal rotor comes into it's own for stability & landing?

It's certainly well worth trying on a land yacht where a bit more weight and a bit less efficiency is less important than good thrust from a rig ½ or even ¼ the area.

 

While writing above I've found a post by AlexanderSahlin (on a boat forum) who used a 2m 2-blade rotor (3kg) to ice-skate across a frozen lake at speeds comparable to using an 8m sail (there's a video of the sail in his 2nd post - it's fast). I'm so grateful for people who push the envelope so I don't have to!

 

The video shows him flipping the sail over his head to tack so I'm going to assume he did the same with his rotor - like an umbrella - no mention of gyroscopic problems.

 

To get to the right page google "alexanderSahlin skating gyrocopter" it's about halfway down.

 

Time for the drawing board now - attempting to crystallise what I've learnt and whether I've got it straight.

 

Many Thanks & Regards.
 

[Richard Harris]

I look forward to seeing what you come up with.

 

A few snaps of my gyri kite for Hammonds TV programme  It took many attempts and variations to get a working kite. I tried two lines first with a self correcting rotor with a pendulum weight, this didn't work. Second attempt I tried two lines again with rudder control, this was ok but uncontrollable as it rolled over. Third  attempt I added a small wing, this was stable but wasnt what they wanted. Forth attempt I attached the line to a 3 point harness which worked but tended to roll from one side to the other.

For the fifth attempt I moved the line attachment high and increased the vertical area and length of fuselage rearwards, this worked well but only in a steady breeze.

To get the Robinson Crusoe look I made it from 10mm dowel, each joint was wrapped in thick cord.

A few photos, the final version has the wheels fitted.

Edited August 4, 2022 by Richard Harris

[Richard Harris]

[Thomas W Shelley]

This looks brilliant, will look forward to seeing it in the show - even if they didn't do a good job of flying it 🙂

[Negative Attack]

Thanks for the design evolution notes - extremely helpful! 

The first 2 photos show a vertical pole that might control the rotor's overall attack? - was that the pendulum arm?

It obviously flies well - I might try your design without Robinson Crusoe's nest?  - at the very least I need a way to examine the lift of various rotor types (assuming I can get something to fly by making the smallest possible changes to  your design). Was it about 1m diameter?

Regards.