Philipp Gardemin

Good morning,

sorry for taking up this old topic. But I found you by Google, searching for all kind of informations about the fantastic "Fairey Rotodyne".

I just started to design a 1:10-model of it. It will get a rotor-diameter of 2.7 m and a wingspan of 1.4 m. I think, as bigger it is, the flying-characteristics will be easier. My plan is too, using the main rotor in a kind of auto-gyro, probably with a small motor inside of the fuselage, which gives to the rotor a first rotation before take off. The model will be build complete in wood, designed and made by CAD and CNC-milling. I keep you informed!

But there is one point I´m not experienced in: How can I build the storing of the 8 mm main shaft in the top of the rotor-tower? It should be able to swing left/right and forward/backward. Perhaps somebody can give me a simple sketch?


Bye

PHILIPP

XE521

Grussti Philipp,

the only thing I can come up with is in effect a joy stick mechanism, wereby the joy stick is the rotor shaft. The potentiometers would be replaced by servos. But this leads to a problem, either you use very strong, heavy, servos or a gear-box to up the torque. If gear-boxes are used then this will slow down the reaction time. I may well be wrong, but as far as I can see if you use any other form of control then you will run into non-linear movement.

Why don't you use a heli swashplate? Simpler, also lighter servos and less weight.

I'll be watching this theme as I also have an interest in this matter.

If you need drawings, large scale, of the original aircraft just PM me or send an email.

Servus.

Karl.

Philipp Gardemin

Many thanks to everybody who sent me an email. Especially "GaryTenPas", who sent me a lot of helpful pictures. Yesterday in the evening I made a big step by drawing the plan. Now I have to draw out all the single parts. Next week Friday I will pick up my brand new CNC-milling-machine in Austria...

@Karl: Bitte melde dich mal bei mir via email. Ich hätte da ein paar Fragen an dich.


All the best

PHILIPP

JCaste

Phillip, I didn't fully understand you. I guess you want to know how to make a device that allows an 8mm shaft to be tilted in 2 axis, isn't it?

BTW, I envy you! I've awlays had in mind to do something veery similar to that, but there's always something on the way...

Philipp Gardemin

Hi JCaste,

yes, you are right. Any idea for it?


Bye

PHILIPP

JCaste

Well, yes. As they have already said, a good option (if you don't want to make any designs and have no machine shop at hand) is buying a commercial swashplate, which won't be easy given the rotor size you aim for. It won't be cheap either.
The other option is designing a custom rotor. IMHO, it's best to leave the shaft fixed for a number of reasons; it's easier, lighter and sturdier. So you basically have a rotor system which is made of 1) fixed shaft 2) universal joint 3) rotor.
If you set the rotor at a certain height regarding the fuselage, then you can calculate where will the universal joint will meet the fixed shaft and you will be able to "hide" the whole system inside the autogiro. If you plan to use a prerotator, then you'll have to add a gear in the rotor and a place to hold the motor to the universal joint.

rickster3057

HI philipp, i have a swash plate rotor shaft pitch control and rotor head from an old kyosho 30 SRT helicopter you can have for free, its just sitting in my shed gathering dust, the way i see it, it would be cool to see you build a fairy rotodyne,wanted to build one for so long,but wanted someone to go through the build first.
For pre -rotating i have the main shaft drive cog and bevel gear you can have as well, you could hide it all in the body.
Rickster3057.

JCaste

Rick, I wouldn't like to spoil your offering, but a .30 sized swash is WAY small for a rotor this size!

BTW Phillip, I don't know what RC background you have but have you ever designed an autogiro before? I mean, a gyro this big is certainly a big investment in tim, money and efforts. Perhaps it would be a wise idea to make a scaled down model of your "rotodyne" (perhaps using the swashplate Rick offers you) to debug most problems, and then go for the bigger one. Of coruse it can work the first time, if you make a sound design, but it would be a shame to a have a poor flier or crash such a model.

rickster3057

Hi Jcaste, oops just read through the thread again 2.7m your right it is 2 small.
I like the ,make a smaller version idea,its a shame a company doestnt make and sell them dont know about you but i would buy one, i think the rotodyne is so out of the ordinary and would be a great flyer.
Rickster3057.

Philipp Gardemin

Hi,

@Rick: Many thanks for your offer. But as JCaste said, its much too small.

@JCaste: I´m a modeller sind 25 years, since 17 years specialized in big electric scale-models. Most of the models are built by myself. I´m the editor of the German model-magazine AUFWIND ([link=http://www.aufwind-magazin.de]www.aufwind-magazin.de[/link]) too. Actual I have enough models in my hangar, that it´s no problem, building a new one without a guarantee of success... I fly a small Autogyro from LA-Heli since one year. It´s simple and easy flight-characteristics obtained me to make it much bigger for the Fairey Rotodyne.

Indeed, using a big swashplate is the best idea for the moment. I have to find one...


Bye

PHILIPP

JCaste

Phillip, as I said I had no idea of your experience, but from what you're saying things should be easier. It was just the mandatory dad-like advice.
BTW, if I were in your situation, I'd go for the custom rotor unless I found a good and cheap commercial swash plate that big (which won't be easy).

JochenK

Philipp,

using a swashplate solution is more or less a must for the Rotodyne. You'll have to tilt the rotor back by about 10° to get the thing flying. Now, if you use a D.C. head like on your Rotorshape and want full head control, you'll have to allow for a further 6° to 10° more back tilt. Think of how high your rotormast will have to be to get you enough clearance at the back of the Rotodyne. It won't look good anymore.

Jochen

fogarty

I recently found a RC DVD I made 5 years ago at LDMFA field in Australia and have been uploading clips to Youtube for posterity , Saw your Rotodyne discussion & thought this clip could be of intrest [link=http://www.youtube.com/watch?v=17i43MTx4o8]RC Rotodyne[/link]

XE521

Hi fogarty,

looks like Don Incoll's kite. Do you have any further info?

Regards.

Karl.

JCaste

I'm of the opinion that, unless it's strictly necessary, it's better to avoid swashplates. I don't know which particular setup used the Rotodyne, but it seems like there's plenty of space for the rotor to tilt. But, to know for sure, it's as easy as finding a good side view of it, drawing a "fuselage mean line" and a rotor path line tilted 9º-12º degrees from that "mean line". If you can then draw another rotor path tilted an extra 10-12º degrees (I'd say not more than 25º overall) and still have a good clearance, then there should be no problems. And those angles should be more than enough. The Rotodyne has a small wing which should provide some lift, thus allowing the rotor tilt angle to be reduced.
Regarding that, the rotor-wing dependance can lend to interesting experimentation. Brainstorming a bit,
- A high-lift wing (= wing provides most lift) would allow you to have a less-tilted back rotor in normal flight -> Less drag -> Somewhat higher velocities and "plane-like" behaviour. You could still allow the rotor to tilt back many degrees, to help with low-speed handling. Anyway, you should always keep the rotor at a minimum angle; else, if you're flying in certain conditions, you could even stop the rotor.
- A low-lift (or nearly 0 lift) wing means the Rotodyne would get most of it's lift from the rotor -> More drag -> Behaviour closer to a "pure" autogiro.
In any case, though, remember to keep the weight really low...Or it will fly like a plane anyway!

It's hard to say this but, that model flies like a drunk hornet. I'm still amazed by how it could survive 2 flights.

XE521

The original Rotodyne used a fixed rotor shaft. Due to the problems of routing the linkage around the air ducting etc. they located the swashplate in the dome housing above the rotors (see below). Because the Rotodyne took-off as a heli the rotor angle could be kept to an absolute minimum. If you want the angle I'll leave it up to you to calculate it from the dimensions show below.

Regards.

Karl.

Edit: Images uploaded.

JCaste

Thanks for the explanation. I wasn't completely sure about the rotor system used on this craft; it's an interesting design.
Referring to the model, I'd say a DC rotor was probably the best solution regarding simplicity, reliability and cost (if there's enough room for the rotor to tilt, of course). A swashplate has more versatility, but that comes with a significant increase in complexity and weight, which IMHO are heavy arguments to go for the DC rotor if you don't need that extra maneuverability.

BTW, very interesting pics! Could you please send me too those files you mentioned earlier in the post?