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Tandem Rotor Helis Vertol Chinook > chinook question
 
 
webbhost
Key Veteran
Location: england - Leicester

hiya, just trying to think of something and part of it is this...

what controls a chinooks left and right movement (tail on a single bladed helicopter), and is a gyro fitted to prevent the wind sending it into a mad spin

also can it be done with two 2 bladed rotorheads?

meh
11-24-2005 Over year old.
HOMEPAGE  
 
 
dkshema
rrProfessor
Location: Cedar Rapids, IA

Differential cyclic and collective input to the rotors. The front and rear rotors are capable of having independent cyclic and collective controls.

And yes, you can do it with two bladed rotors, as evidenced by the small electric powered Chinook for sale here:

http://www4.mailordercentral.com/he...p?number=173470

The number of blades has nothing to do with how you control things....

Dave
11-24-2005 Over year old.
 
 
mrNoodles
rrProfessor
Location: Borlänge, Sweden

Here you´ll find some info, and theres more if you do a search.

Impressive mechanics on the 'older' Vertols

I think that the new Hirobo Vertol/Chinook uses a 3way gyro.
11-24-2005 Over year old.
HOMEPAGE  
 
 
webbhost
Key Veteran
Location: england - Leicester

someone guessed it, im doing a little research because im interested about building a home made chinook out of 2 raptor 30's

going to use 2 sets of radio systems, on same frequency so that cylics can be cynchronised etc.

Left and right cylics would be easy peasy, both go same way on both heads.

Im "guessing" for foward flight, the front blades would tilt fowards, and back blades tilt backwards, i.e. front end pushes down and back end pulls up - am i right? (this could be achieved by having one servo reversed and turned around if necessary)

im also guessing id need 2 engines(2 new engines would mean having a better engine power from both (both would be roughly the same) - having the 2 main cogs connected via a drive belt would mean that having different headspeeds would be impossible, which would be a drawback for left and right turns (im guessing that the turning is generated by a slight difference in rotorhead RPM s)

If im wrong i think i have ALOT of research to do, (ok i need to do alot of research anyway before trying anything this stupid)

Im going to look at a thread about a previously made raptor chinook, might give me some good information

meh
11-24-2005 Over year old.
HOMEPAGE  
 
 
webbhost
Key Veteran
Location: england - Leicester

ok it just occured to me that to keep the blades from hitting each other, both rotorheads need to be connected via a drive belt, and need to be at the same headspeed. This could get rather confusing lol.

to make the chinook turn left (i.e. on single bladed, tail moves anticlockwise), would the back rotors tilt to the right and front rotos tilt left (I.E. cylics counteract each other keeping the helicopter level, but causing a counterclockwise rotation)

Im guessing the main steps would be - firstly connect rotors via drive belt so that they are | and ---. As for the cylic movement and the (would be tail) movement, its all down to cylics mixing


meh
11-24-2005 Over year old.
HOMEPAGE  
 
 
dkshema
rrProfessor
Location: Cedar Rapids, IA

Go with a suitable single motor. It's hard enough to get one motor running consistently on a heli, two would be extra weight, and mechanically messy, not to mention trying to sync the RPM.

You also need to synchronize the MR blades since, if not synced properly, they can occupy the same space which would be disastrous. The syncing is easy to do with a single motor, nearly impossible with more than one, unless they are driving a common transmission.

Go with a single radio, as well. There is no need for two.

As you can see from the exploded view above, the mixing is done mechanically in the servos setup, and most likely electrically in the TX as well. Collective and cyclic inputs go to the MR just as in a single rotor system -- through the swashplate. Your setup just needs to coordinate the two separate swashes.

Your assumption about the front blades tilting forward and the rear blades tilting backwards for forward flight is flawed -- think about it. That kind of action would cause you to go nowhere, as the forward lift vector of the front system would be cancelled out by the rearward lift vector of the rear system. You would apply a bit more collective to the rear system (possibly at the same time reducing collective on the front system. The end result is that the rear of the heli rises a bit, giving you a resultant lift vector in the forward direction.

What you are planning on doing has been done. Look through the Galleries here, you'll see a couple of helis connected by a common boom, and the thing flew. If you find the gallery, you could contact its owner for details of what he did, and how it worked.

Dave
11-24-2005 Over year old.
 
 
ddavison
Veteran
Location: Brownsville, Pennsylvania

Did not know if it was stated ,one head spins clockwise and one anti-clockwise

DaveDavison, Miniature Aircraft Field Rep.
11-24-2005 Over year old.
 
 
GroundPounder
Senior Heliman
Location: South Africa, Cape Town

Quote 
Im "guessing" for foward flight, the front blades would tilt fowards, and back blades tilt backwards, i.e. front end pushes down and back end pulls up -


That wouldn't work!

Both need to tilt forward, and collective added, as per normal heli.
And yeah, the heads need to be mechanically interlocked.
I was thinking, Raptor 50 mechanics, Raptor 30 blades, one TT50 engine, electronic mixing in the heli.

GroundPounder
11-24-2005 Over year old.
 
 
webbhost
Key Veteran
Location: england - Leicester

You also need to synchronize the MR blades since, if not synced properly, they can occupy the same space which would be disastrous.

yeah, thats when i figured i cant have 2 motors.

To synchronise them, they would have to be connected via the belt that goes through the boom

I figured it might be an idea to fit another motor in (without clutch) to even the weight out on both sides - i figure i cant use both motors at same time to try and provide more power, because each rotorhead would need to move in opposite directions - 2 rotors running at once would mash the gears up bad)

meh
11-24-2005 Over year old.
HOMEPAGE  
 
 
dkshema
rrProfessor
Location: Cedar Rapids, IA

From the gallery of "Dave P" here on RR:



It's his.

For some fun, go to this post:

http://www.runryder.com/helicopter/...ht=tandem+rotor

and click on the link in the top most post from Dave P -- cool video of a Chinook at an airshow. Never thought I'd see a Chinook doing that kind of stuff...

This link has a link to a video of Dave P's tandem flying...

http://www.runryder.com/helicopter/...ht=tandem+rotor

Dave
11-24-2005 Over year old.
 
 
webbhost
Key Veteran
Location: england - Leicester

Quote 
Both need to tilt forward, and collective added, as per normal heli.
And yeah, the heads need to be mechanically interlocked.
I was thinking, Raptor 50 mechanics, Raptor 30 blades, one TT50 engine, electronic mixing in the heli.


now that i think of it, that would probably snap the tailboom? lol

If both cylics went foward, would the back end need more collective than the front end?

meh
11-24-2005 Over year old.
HOMEPAGE  
 
 
dkshema
rrProfessor
Location: Cedar Rapids, IA

The post above with the exploded diagram of the Hirobo Chinook is from the older kit, most likely.

Hirobo recently re-engineered the Chinook and now the mixing is done by an included electronics module....

Read about that here:

http://www4.mailordercentral.com/he...p?number=406905

You've taken on an ambitious project. Good luck with it. I'm sure that you'll enjoy it and we'd like to see how the project progresses.

Dave
11-24-2005 Over year old.
 
 
dkshema
rrProfessor
Location: Cedar Rapids, IA

You're also in luck, Dave P is on the same side of the pond as you are...you might be able to talk to him in person about his effort and both of you might be able to help each other....

Dave
11-24-2005 Over year old.
 
 
webbhost
Key Veteran
Location: england - Leicester

taking in mind im quite new with heli's i might try it with 2 T-REX's before i try it with a nitro lmao..

Also if i do take out the project, it wont be done any time soon, i need to buy 2 helicotpers first lol..

ill have to look into that hirobo mixing unit and see how much it would set me back.

either that or... it would take 5 channels to work it - 2 for each cylics and 1 for throttle...

i could put my throttle on a side slider, and then have my 2 sticks controling 1 set of cylics each (if i understand how the heads work, and would have the skill to work each rotor head individually

meh
11-24-2005 Over year old.
HOMEPAGE  
 
 
webbhost
Key Veteran
Location: england - Leicester

with a little practice i dont think it would be too hard

Controlling each rotorhead individually would be a cheap way of doing it, - althrough at the same time it could turn out to be like trying to hover first time using a heli or simulator lol..

Maybe spend out on a few gyro's to help on the cylics through lol

i do know it would be a really nice challenge doing it like that too.

Hmm another thing strikes me, needs more than 5 channels.

Maybe if i put throttle on a governer channel, and then 2 channels for each pitch

Modify a cheap controller with 2 sliders on each side -

You get a switch that would activate throttle, and let a governer keep the RPM, modify the left stick so that the click movement is gone and you have a springed stick, like the right hand stick.

This gives you 2 cylics which will work nicely, and can be trimmed seperatly.

Each slider will control 1 rotor pitch.

To move foward, move both cylics fowards, and apply more blade pitch to the rear end, to move left and right cylics, push both sticks to the right, and vice versa. To rotate heli, move cylic sticks in opposite directions (I THINK?) - counters to keep helicopter upright, but because of the cylics being tilted, wind direction would make the helicopter move in circles?

Also im guessing that having 2 rotor heads that counter-rotate - this would eliminate the biggst need for a gyro as is the same with the little indoor ones with counter-rotating blades?


Edit --

on second thoughts im guessing for foward flight, back would be higher in pitch (until the helicopter is tilted fowards, then as the helicopter progresses fowards, pull back onto the cylics, so that the blades are horiontal. (pull back to this point when you have enough foward movement).. to stop the foward flight, you would increase front pitch, and push foward on cylics etc... Me thinks i have something going here lol ill have to post the link of the thing crashing into the floor when it happens.

Id also guess that by keeping your cylics horisontal, but back higher
than front, you can also hover it at a angle.

Hardest bit i think would be connecting the tail boom to both helicopters, would have to shorten the boom, and cut out a D shape from the tail end so that it can fit into the other raptor. - would also have to be done in a way that keeps the helicopters exactly parralel with each other - have to be very accurite.

This could be interesting.. atleast with 2 raptor 50's i would have 2 chances at gettign the tailboom correct lol.

would also have to figure out how im going to get the belt twisted 180 degrees without causing binding in the middle.. that bit is going to get me thinking - unless i have the boom there for support and divert the drive belt via a seperate method. 1 option i would have would be to try and insert a tail cog 1/2 way down the shaft, thus the belt has to run on the belt and not on the other side of the belt

meh
11-24-2005 Over year old.
HOMEPAGE  
 
 
webbhost
Key Veteran
Location: england - Leicester

well ive done some thinking, ive figured out a way to turn the drive belt 180 degrees without binding it. Theres only 1 thing that stands in my way.. this experiment would cost me ALOT....... you got 2 raptor 50's at £280 each (thats £560 for the helicopters chassis)
I got quick UK tail servo mounts needed also, probably about 4 (this is to support the tailboom in conjunction to helping the belt rotate 180 degrees. I got 2 engines (one new working, one broken to counter the weight of the other engine and give the helicotper a good centre of balance) - lets say thats another £210? (OS 50 hyper, and an extra £50 for a broken engine to counterweight), and most importantly, i got electronics - 1 reciever, 1 battery, 7 servo's .. 7 good servo's is gonna be what £700?

lol..

And it could all go kaboom on takeoff...

One question, wondering if anyone knows this one..?
Would the distance between the 2 rotorheads have to be anything specific, or as long as its far enough out to prevent the blades hitting each other or smashing the other rotorhead, is that far enough?)

meh
11-24-2005 Over year old.
HOMEPAGE  
 
 
Phil_Mart
Veteran
Location: Newcastle UK

Hi webhost, have at look at my clubs site Cleveland Heli . The article on Chinooks, two guy's with two totally different approaches, but both with flying system

Philip Martin.
11-24-2005 Over year old.
 
 
Eyal M.
Heliman
Location: Israel

Hi Wbbhost,
The right way to control a tandem is using an onboard mixer to control the two rotors and for sure NOT using two radios .
I started my first tandem by connecting two helis back to back and continued to design my own mechanics, transmission, rotor heads and fuselage, all are self designed and manufactured.
If you want to do it right, use the TH-2 mixer from www.tech-mp.com and any 6 ch radio will do, no need for any special mixing, it's all done on the TH-2 mixer. You will need a gyro for Yaw and I recomend a Co-Pilot to stabilize the roll and pitch axes, but you can use also two gyros for that.
You can look in my gallery here on RR to see some pictures of my huge tandem the CH-113 (the Canadian version of the CH-46).
Also we have a special web site at - http://www.rchelicopters.nl/
dedicated to tandem projects where you can see several guys as Martin and myself, each with his own design and solutions. My heli is one of the two largest scale in that forum (mine is 1:6.8 and the other chinook of Machiel is 1:7 scale). So if you really want to go into that project and do it right, first look at some pictures and videos and we can help you with advice.
Regards,
Eyal.
11-25-2005 Over year old.
 
 
webbhost
Key Veteran
Location: england - Leicester

hey, i have no intention of using 2 radio's.

I will put throttle onto a switch, ( so switch up = 80% power say, and governer kicks in. Switch down = idle so Govnerner is disabled.

Pitch curves for both rotorheads would be controlled via the up and down on both sticks, left and right cylics on both sticks, and use the side sliders for the fowards and back cylics

Of course it means i would have to learn to fly all over because i an controlling 2 rotorheads manually... i might be better just buying a real chinook (althrough that would take the idea of me wanting to try something new because im not really too bothered about a chinook, im bothered about making a home made one lol)

meh
11-25-2005 Over year old.
HOMEPAGE  
 
 
Sea King
Senior Heliman
Location: England UK

Why use the two engines Would it not be better to balance the heli using the Battery packs, electronics, Fuel tank etc etc
Carrying a non working engine is pointless
If your up the club on Sunday Lets have a chat LOL

Roger
11-25-2005 Over year old.
 
 
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Tandem Rotor Helis Vertol Chinook > chinook question
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