Rotcivv17

Guys I have been thinking about this and I really think an osprey can be designed. Servos for the engine tilters, and servos for everyother control surface. Thing is, the large props, how can we get strong enough engines for bib props without too much weight? There are a lot more issues, but i think this can be designed, let me know what you think The Osprey is that twin engine plane that tilts the engines upwards for VTOL and then forward for forward flight. Thanks
Victor

vtol_maverick

You're on the ball dude!

I've started a similar project of a BA609 tiltrotor. (sleaker than V22)
The engines I am using is the RCV 4 stroke. It is geared down on 2:1 ratio. see www.rcvengines.com they do direct orders.
I've got 2x 60's that turn 17x12 props, but they limit the model's total mass to 4kg, so you should go for the 90 size ones.

My engines will be linked to a solid shaft, rodded to a 1 or 2 large servos in the fuz.

My approach is more plane than chopper, so I will use thrust vectoring from a small d/fan in the fuz, to control it when hovering.

vtol_guy

hi there you 2

i see that i have discovered 2 more vtol people lol

i've been working on this bugger for over a year now and trust me you ARE digging into something deep here

i've already gone through 2 massivley designed and built designs both of which have failed and i've put a good solid 100 hours total into designing, probaly more than that

i'm not saying don't do it but if you 2 want then i'll share my knowledge with you and hopefully help you to accomplish what i'm still trying in your first or maybe second design

let me know anyway

vtol_guy

actually i have a bit time free at the moment so i'll give you a little start off

i'll begin with the major things first:

1. Tilt mechanism: servos are not strong enough, trust me i've tried and seen others try, the only servo i could see working is a big sail winch servo. The way in which was solved was to modify a servo so a motor spun a worm gear through a small nut which caused this to go back and forth which was linked to a pivot and hence you get tilt there.

2. Weight: these things have to be as light as possible but also very strong around the tilt arm area and the engine areas. Props to be used should be fun fly props for maximum thrust

3. Contols: i've seen some people use 11 channel computer systems with endless amounts of mixers and stuff like that jammed in but i designed a much simpler way to do this with a 5channel radio. Only drawback is that it can't be incorporated into an osprey, search for a plane called the dynavert and you'll see a tilt wing. Basically. If the wing is tilted upwards with the engines mount to it. You can use the prop wash, make the elevons go forward and the whole plane will tilt forward, same for back and one up and one down will cause you to yaw, just think about it and you'll see what i mean.

For roll control you have to change the engine speed of either left or right engine.

I have a diagram somewhere but basically roll in heli mode was the same to control roll in plane mode. The pitch and yaw were all same although there are problems with yaw control in plane mode.


The above is only the very very basics so just ask any questions either of you have and i will do my best to help and show me any pics or new ideas you both have

my latest design will hopefully work, I'm using the airframe of a limbo dancer converted to having to MDS .18's instead of the MDS .38 in. Take out the 2 servos in fuselage to control throttle and elevator and mount these in the wings. With the spare area you can put the rotation mechanism in there. If you have any questions then just ask.

thanks,

tiggerinmk

I'll wager a bet that with the release of the Realflight Add-ons 5 you'll seee a lot more interest in this area...

Any further thoughts or progress on the design of the tilt rotor/wing mechinism? Thoughts on strengthening the wing to cope with an engine pod on each end?

vtol_guy

hey tony

i'm using 2 retract servos now for the tilt mechanism. Look in the topic thing i made in this forum for more info about it. I'm going for a design similar to the vertigo now. Single engined design, less expense!

Rotcivv17

How about a retract servo geared down?????

vtol_guy

last time i tried to make a simple modification to a standard servo i went through about 5 of them before i finally got it right! lol

i've done my maths (and i thought i could escape from it during xmas) and worked out i can do with just one of these now which is a good thing (less expense, yey!) lol

Mitek

About the dynavert
Why does the airplane have a tail rotor. Doesn't it have counter rotating props?
I might be wrong, but you may need to have some pitch control in order to control it in hover. Please correcy me if I'm wrong

khlash

My Feedback: (6)

I dont mean to sound negative, but if they cant even get the real one to fly reliably.....

tiggerinmk

The majority of the full size crashes have probably been due to pilot error. If you try the Realflight version, it flies quite well but you still need to be careful in the hover; if you let it tilt backwards it will flip over onto its rotors....

As for the models, people all have their own ideas on how to make it work with varying degrees of success.

From my own point of view (if I get around to building it) I'm treating it like an aeroplane with standard props, and will start testing with the engines horizontal. I may just stop the nacelles short of a true 90 deg so that the plane won't actually hover but will be STOL capable...

vtol_guy

the dynavert doesn't use cyclic controls so uses a horizontally mounted tail rotor to allow it to pitch back and forth

as for the height control using fun fly props, it will work, just use the throttle speed to control the height, obviously this isn't as good as using collective controls but i can't fork out that money and i'm sure others won't want to either when it can be done much cheaper

Mitek

How iwll you control pitch, or are your just going to hover for a slow time and then immediately transition into forward?And wo'nt spiinning the tail on the dynavert cause some yaw sue to its torque?

tiggerinmk

Back to the Osprey.....
A colleague here gave me a print out from an article in today's edition of a local paper.

There are a couple of interesting points:
1. Crashes:
There were two crashes that resulted in the Osprey being grounded. The first crash in Arizona, in April 2000 was caused by an aerodynamic condition called 'vortex ring state' which can occur when a rotorcraft descends too quickly while moving slowly forward, losing lift due to its own rotor turbulence. The North Carolina crash in December 2000, was caused by a hydraulic leak and compounded by faulty flight control software.

2. Rotor System:
I have said several times that the rotor system does not have a cyclic or helicopter head. This is plainly evident from the many pictures that are available of the craft. From my observations, I can see that the rotors are varible pitch turboprop units, the sophisticated flight controls probably therefore operate by sensing the attitude of the aircraft and sustain a stable flight path using a combination of pitch adjustment on the props and the small adjustments in the nacelle angle.

A quote from the paper:
"The V-22 is a hybrid design with fixed wings and propellers that can tilt upward so the craft can take off like a helicopter, then rotate
forward so it can fly like an airplane".

vtol_guy

the tail rotor is a 2 rotors mounted on top of each other travelling in opposite directions, in normal plane flight the tail rotor is stopped and locked in place so as not to interfere with the flying

aerobracken

My Feedback: (1)

Hi All,
I got as far as scaling the osprey down, then gave it up for a giant scale b-25 (but its still going to be built). I figured I'd give you a few of my ideas. First, you may be able to use worm gears. Thes are commonly used in variable geometry models, like F-14's. It ca be actuated by servo, or from servo to a motor. This would give a very sturdy setup that would allow for slow transition of the props. Also, since the osprey has instabilty issues, it might not be a bad idea to look into a single, center mounted engine. This would preferably be gasoline, giving the efficiency and necessary torque. It could go into a small differential, of sorts, or maybe a belt drive much like a heli would have. Though this would require a bit more designing (which I am in the middle of right now), it could definitly make the model much more stable, because there would be no difference in propellor speed, which would be the case with a twin engine setup.

Good luck with your designs, and I'd like to see them!!
Phil

runover1

My Feedback: (10)

Now I am new to this stuff, but the Osprey has me intrigued. There are a few ways to tilt the rotors and the mention of the F-14 reminded me of the swing wing motor that uses optical sensors for positioning. I wonder if you can hook this up to a flap control like in Real Flight. Now on the roll control, could you design an airbrake style flap that opens behind the prop wash in the nacelle to give more drag? If you were able to get it right and maybe use a gyro, you could keep left and right level simply with "airbrakes on either side. I think it would take some experimentation, but what do you guys think about it. I think you could have an "Axle" in the shaft that would tilt the engines. I would still use two servos for redundancy, but I think it would work. What size engines are you guys experimenting with? Anybody got a good site for 3 view prints and specs?

vtol_guy

i've stuck with size .40 engines, seems to be the general trend but some have gone higher than that up to an RCV .60 i think it was.

vtol_maverick

Im the nut with the RSVs![&:]
The good thing about the RCV is it is geared 2:1, so it can take bigger props. Im going for 18/10 3 blades.

ps Does anyone know if 3 blade or 2 blade is better for VTOLS?

vtol_guy

2 blades are more efficient but i think i need to go for a 3 blader, i can't fit a bigger 2 blade prop on now and that engine is screaming like a 2 year old child, VERY LOUD! lol

nav8tor

tiggerinva,

It may not look like it in the pictures, but I can tell you that the Osprey does have full helicopter cyclic and collective controls. The controls are hidden behind aerodynamic fairings .

Lee

angelrcdesign

My Feedback: (40)

[img][/img]Hi guys my name is angel angelrcdesign, the Osprey is not that hard it take some time ok. I am going to use one motor for the prop,running off the main mask,geared to both side wich counter rotate both props. Two main shaft are control by washplate wich tilt the plane fr/bk and lock one side of the washplate for ali. so your mix will be rud/ele,split ali.that work on the out side prop.[sm=bananahead.gif]

angelrcdesign

My Feedback: (40)

Don,t you thing the osprey look good on realflight? How about taking the real osprey mesurement (Ft) to (in) which scale it to about 58in.fus 46in,wingspan 22in,heght overall with 84in, with the rotorblades. is that a reasonal size.

Ram-bro

My Feedback: (101)

Hey guys here are a ew of my thoughts on the topic.Some of te concerns we ahave when it comes to this design are weight, vibration, the tiltiing mechanism, control in flight and K.I.S.S., Here is what I would propose just to get things rolling. Try electrics on a full tilting wing that would be hinged at the rear , oversized flaps/ailerons in direct path of the prop wash ad lets start with something like a trainer. From what we gather info wise from this, acourse you would scale it up. What do you guys think?

runover1

My Feedback: (10)

i think it would be a great way to start. I still don't know if I would hinge it from the rear. I wonder if you could use a gyro for controlling the motors.