Discussion A Fairey Rotodyne Story!

[SafeLandings]

Hi Guys,
I have had delivery of my Fairey Rotodyne ABS moulds today, not the prettiest of Autogyros but it will be very challenging to say the least!
To be honest I dont hold up much hope for getting this off the ground but I will give it my best shot.
I thought I would show you a few photos of what I have and what the original model looked like made by Jim Morely. His version was a helicopter and flew very well, to me this thing should fly like an autogyro so this is what I will attempt to do.
I have no idea about CG positions etc so I would be happy for people to give their 2 pence/ cents worth.
When I will make a start I do not know, but as I progress I will add what I have done to this thread.

I think a simple test bed should be built first off to prove that it can fly?

Regards To all


Rich

[ssrobzoom]

Hey Rich,

Where did you get the molds from?

[SafeLandings]

An English chap by the name of Jim Morely, he built a heli version a few years back and I met him at the Rotorary Eagles meet at Charlton Park. He could see how enthusiastic I was about Autogyros and contacted me days later offering to get a set of moulds done for me off his originals... jyust in case I had 2 sets

I have looked over them and it is going to be a bit more complicated than I first thought.


First stupid question is ...What is the best way of joining ABS together?


Regards Rich

[thechannelmast]

how about gorilla glue the clear quick set

[MarioIArguello]

Originally Posted by SafeLandings

An English chap by the name of Jim Morely, he built a heli version a few years back and I met him at the Rotorary Eagles meet at Charlton Park. He could see how enthusiastic I was about Autogyros and contacted me days later offering to get a set of moulds done for me off his originals... jyust in case I had 2 sets

I have looked over them and it is going to be a bit more complicated than I first thought.


First stupid question is ...What is the best way of joining ABS together?


Regards Rich

Rich,

Abs or styrene can be glued in various ways. One very clean method is to use a fine point artist paint brush dipped in a solvent called Ketone and run that along the seam of the two plastic parts to be joined. The ketone melts the plastic and forms an almost instant bond. I use this procedure for assembling plastic scale models made from styrene, abs should also work the same. Before using ketone I had tried acetone and paint thinner but they are not strong enough. Acrylic cement IPS Weld On 3 has been suggested to me but I never tried that. You can also use the hardware store ABS-PVC pipe adhesives, they take a little longer to set. Ask your mold provider also if he has any suggestions, most people that do vac forming will tell you what works best for them also.

Another approach I use for quick assembly of thin styrene-abs plastic parts is to brush one side of the part A with a quality Hobby CA accelerator and run a thin line of similar quality CA glue on the other part B, you have to be good at joining things together because this is a one shot and cannot be redone, as this is an instant bond.

[Kiwi]

Are you reading this thread?
http://www.rcgroups.com/forums/showthread.php?t=947879

[JochenK]

Rich,

I think there are two things that need some consideration. First: you are basically joining a fixed wing aircraft with an autogyo. Which means that the c.g. necessary for fixed wing operation should be about in the same position as the c.g. necessary for the rotary wing operation. Second: you'll need more rotor back tilt than the original had. To keep the necessary rotor back tilt down to a minimum, build as light as you can. If you can keep the disc load down to something like 6 g/dm² or 2 oz./ft² you should be able to get away with a rotor back tilt of 8°, maybe even less if you're using a big rotor. The less rotor back tilt you need, the easier it will be to obtain the correct c.g. positions, too.

Jochen

[SafeLandings]

Thanks for the tips mario

Jochen,
I think you are right about the weight, I need to keep it simple and as light as possible. The CG will be the main issue, if you watch this video do you think that the chap had the CG set as per fixed wing? It looks to me as though he has a rigid rotor too?
As he was getting up to speed on his take off run all seemed fine then when the rotors got to their lifting speed the model just ballooned up!
To be on the safe side I would sooner have a nose heavy gyro because there are to many unknowns. Am I right in thinking that the stub wing will reduce my disc loading once everything is in forwrd motion past the stall speed?
Im thinking of building some kind of profile Rotordyne to experiment with to try and get all this sorted before committing

I have taken a look around the moulds and my rotor span will be around the 60" mark.
heres that video

RC Fairey Rotodyne gyroplane Crash (2 min 38 sec)

Regards Rich

[SafeLandings]

I have also been thinking of roll control, looks like the original had ailerons which maybe ok for forward speed when it is flying fast enough. Do you think roll control on the rotors would be a good idea too? The only problem I can see is the restricted movement that the rotors could make before striking the outer fins?? For sure they will have to have some kind of adjustment as we all know the blades will need some kind off trim for forward flight.

The more I think about it the more interesting it is becoming



Regards Rich

[JochenK]

Rich,

if you stop the video after 7 secs and have a look at the still, everything seems alright. The rotor thrust line roughly coresponds with the rear of the blade's shadow, passing through the wing at about 40% chord. With a c.g. at 25% chord I would not have expected major problems. The first part of the take-off looks good, but then around 52/53 secs the rotor begins to cone which may have shifted the rotor thrust line in front of the c.g., causing the Rotodyne's rocket-like climb. Or it may simply have been a c.g. position that was too far back from the start, I don't know. But the c.g. was certainly too far back for a successful flight, in all three attempts.

Yes, your disc loading will be lighter when the airfoil produces lift. And a profile Rotodyne with the possibility of easy adjustments seems a good starting point.

Jochen

[pluriel]

It looks like it was trying to take off and fly as a fixed-wing, the problem started when the rotor got up to speed, after which it seemed to cause too much drag. The model seemed to be flying faster than the speed at which the rotor worked.

[MarioIArguello]

Rich,

If you have an RC sim you can easily test a lot of experimental model aircraft.

I modified one of my sim autogyros with a wing and added two engines to the wing. The model behaves very similar to the one seen in the You Tube video link you posted, of the real RC model. From this it is very easy to tweak the model to arrive at a working one that one can fly with a little more confidence that it will fly without any surprises. Off the top of my head, I can tell there is a lot of coupling between the wing and the rotor and this can affect the attitude of the model. Location, surface area, angles etc...

I have not bothered to check to see if there is even a rotodyne sim model already done for RF, but I did this quick just to give you an idea of what can be achieved with a sim, but the model is nowhere perfect, it needs to be tweaked. If I have time I will tweak it and a foamie profile model build is preferably the way to go before risking a plastic molded one.

The base model onto which the rotodyne experimental is built on, is a Cierva sim model I downloaded from the KE forum, but the model did not fly well, so I spent a good week fixing it to make it fly like a real cierva RC model autogyro, videos posted on my You Tube ch.

High Performance Autogyros RF G3.5 RC SIM (1 min 38 sec)

The rotodyne sim model, will probably take that much time to tweak it, working 1-2 hours a day.

[SafeLandings]

Mario,
I admire the flight simulators and look forward to the Rotordyne but...do these autogyro simulators really fly like a model?
When I fly my autogyros I am playing all four sticks most of the time when turning depending on which direction the wind is blowing etc..sometimes opposite roll to what you may think.
Do you have to add all these parameters as you are building a 3 dimensional virtual autogyro?

When you build the rotordyne digitally how will you know how such an autogyro will react? taking into consideration CG the stub wing etc or just you just take an educated guess?

I do find them fascinating but I would much rather prefer to be out in the fersh air crashing!!


I have been looking around my shed and in the corner covered in balsa dust is my old DAG-R1..to save me building something new perhaps I could add an aileroned wing to this for some testing. I know it has a single engine and looks nothing like a Rotordyne. If I were to make a removable wing so that I can find out the differences between with or without a stub wing it may give me some ideas..what do you think chaps?



Regards Rich

[imsofaman]

Man.....I hate seeing that guy destroy such a nice model in that Youtube video.

The other guy on the scale thread is doing one Hell of job on his. Won't be long before he is flying.

Rich...I knew you were quiet for some reason. LOL! Good luck....

[imsofaman]

Looking at the photos....it seems he has variable pitch on the tractor motors and must be geared to the main shaft. Very nice!!!! A lot can be done with that set up. Very interesting...