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Remember Seth Cochran - 6/17/2002 10:08:28 AM   
Mike James



Posts: 2429
Joined: 1/19/2002
From: Anchorage, AK, USA
Status: offline 		I don't have technical commentary on this thread... I just wanted to say that you are a brave man for attempting this project. "Ambitious" might be understating it.

Hopefully you'll read and absorb all the information here and elsewhere, and keep trying. This is very cool, and as long as you can afford it, and you're safe, I say "Why not?".

Remember, if it wasn't for Seth Cochran, we wouldn't have warp drive!
Sincerely, good luck.


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Mike James
RC Design and Building - www.nextcraft.com

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NEED HELP!!! Scratch-building a V-22 Osprey - 6/17/2002 2:19:20 PM   
Cactus.



Posts: 6138
Joined: 12/19/2001
From: CamborneCornwall, UNITED KINGDOM
Status: offline 		V-22, i love that gimbeled little thing on your page. it gos to show my ideas are to simple for a propperly working final version, but i knew that anyway.
look at [url]www.draganfly.com[/url] for a few ideas of how to use your rotors for yaw control and so forth

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My half dead website www.philsrcworld.fsnet.co.uk new site coming soon.
Redruth & District model flying club www.rcflye

(in reply to Noah-Moore)
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NEED HELP!!! Scratch-building a V-22 Osprey - 6/17/2002 3:43:28 PM   
v22


 

Posts: 85
Joined: 2/24/2002
From: howe, IN, USA
Status: offline 		Phill
Yep ,I guess you can keep it simple ,but to do all the stuff the real one does you need all the heli stuff .I don't just want to jump into the air like a funfly hover plane and flop out of the sky into a controlled crash type of vtol landing.I guess I am just to picky

Yes I have a Roswell flyer which is the same as a dragofly and that would work if you were to build a quad rotor tilt rotor ,but bell don't have plans for that until this two rotor version takes off.P.S. I have tried to make the roswell into a quad rotor and it doesn't have enough lift to support any tilt system.

ttyl
Larry

(in reply to Noah-Moore)
       Post #: 28

NEED HELP!!! Scratch-building a V-22 Osprey - 6/17/2002 4:56:25 PM   
Cactus.



Posts: 6138
Joined: 12/19/2001
From: CamborneCornwall, UNITED KINGDOM
Status: offline 		as far as i know, the Osprey has vairable pitch, not a heli blade set up. very low pitch for take off, and high for forwards flight.
its hard and heavy to do this, but you can use fun fly props and electric motors for very good control. the original indoor helis had fixed pitch.
i can hang my planes very controled, and electric motors have even more control and responce. a propperly balanced set up should gently hover into the air. pilot skill will say how smooth this is
i'd imagine the real one controls pitch with subtle auto movements of the nacells. after all, it carrys troups, they mess the CofG up real good.
am i also right in saying it dosnt truely hover? rather tilts the rotors forwards slightly and STOL
thats solves a whole heap of problems

_____________________________

My half dead website www.philsrcworld.fsnet.co.uk new site coming soon.
Redruth & District model flying club www.rcflye

(in reply to Noah-Moore)
       Post #: 29

NEED HELP!!! Scratch-building a V-22 Osprey - 6/17/2002 8:42:01 PM   
Noah-Moore


 

Posts: 101
Joined: 4/23/2002
From: San Francisco, California
Status: offline 		phillybaby is right in that te real Osprey has variable pitch blades, NOT a heli setup. I've heard of variable pitch blades on models before, but those were on bombers and warbirds. Any use for a project like this?

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know more - 6/17/2002 8:44:55 PM   
Johng



Posts: 1817
Joined: 1/24/2002
From: Deland, FL, USA
Status: offline 		[QUOTE]Originally posted by phillybaby
as far as i know, the Osprey has vairable pitch, not a heli blade set up. very low pitch for take off, and high for forwards flight.[/QUOTE]

The Osprey does indeed have cyclic pitch control of each blade, just like a helicopter. I don't recall if it uses a swash plate or independent actuators for each blade - but the blades are controlled cyclicly - like a swashplate - when in hover.

[QUOTE]its hard and heavy to do this, but you can use fun fly props and electric motors for very good control. the original indoor helis had fixed pitch.
[/QUOTE]

But they had swash plates, didn't they!


[QUOTE]i can hang my planes very controled, and electric motors have even more control and responce. a propperly balanced set up should gently hover into the air. pilot skill will say how smooth this is
[/QUOTE]

Planes can hover because they have tailsurfaces to deflect the propwash. It's not just the motor. If you are trying to develop a scale V-22 - there are no control surfaces behind the prop. The above example isn't relevant.

[QUOTE]i'd imagine the real one controls pitch with subtle auto movements of the nacells. after all, it carrys troups, they mess the CofG up real good.
am i also right in saying it dosnt truely hover? rather tilts the rotors forwards slightly and STOL
thats solves a whole heap of problems [/QUOTE]

No, none of the above is correct. It can do a rolling takeoff, but it is not a requirement of the aircraft . Hovering for TO and landing is normal. I've seen it myself, quite impressive, as is the transition to forward flight. Pitch is controlled with cyclic input to the blades - heli style. Why would you think it's easier to swivel a whole engine/nacelle/blade assembly than to just use cyclic?

Phily, you need to educate yourself before coming on here and telling someone (V-22) how to do it. He's obviously considered the issues at hand alot more than anyone else here. They S/N ratio of your posts is quite low.

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John

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NEED HELP!!! Scratch-building a V-22 Osprey - 6/17/2002 9:45:56 PM   
MinnFlyer



Posts: 19353
Joined: 4/22/2002
From: Willmar, MN, USA
Status: offline 		I think this will settle it:

http://www.boeing.com/rotorcraft/military/v22/1687-a3.html

It clearly shows that the V-22 Osprey has got helicopter-type roter heads

_____________________________

Mike B.
AMA# 42400 www.gettingairborne.com

"Those are my principles. If you don't like them, I have others." - Groucho Marx

(in reply to Noah-Moore)
       Post #: 32

NEED HELP!!! Scratch-building a V-22 Osprey - 6/17/2002 10:36:44 PM   
Cactus.



Posts: 6138
Joined: 12/19/2001
From: CamborneCornwall, UNITED KINGDOM
Status: offline 		whats S/N ratio ?
i didnt claim to know anything, i said ages ago if you want a million dumb ideas and maybe a good one ask me.
for me its Lazy options and cheats
( btw, that brushless motor is now for sale at WestonUK )

ok, blades, your saying that each blade turns as it gos round, so it acts like a heli set up, clever.... but impractial for models
reminds me of that snellflight heli that controls its tips motors in the same fashion.

Yes they had swashplates, i said fixed pitch because i was compairing heli blades to planes props for the purpose of hovering. you also dont have those high drag issues with the forwards flight if you use aircraft props. theres a turbine aerobatic model thread you should look at, hes overcomming all these drag problems

Hanging planes, yep, we have tail surfaces, but again, the refrence was to the amount of control you have over the thrust and there fore the ascent and descent rates. nothing to do with hovering a fun fly. my hangs are all over the place, but i can control height ok.

i said am i right? not i am right. its only a model, cheat if you have to, if you dont mind losing hover and all its problems go for a STOL
it's a start.

And maybe thats where my one good idea was in all this, build a simple test bed. so now i'll let you all get on with it
Toodle pip

_____________________________

My half dead website www.philsrcworld.fsnet.co.uk new site coming soon.
Redruth & District model flying club www.rcflye

(in reply to Noah-Moore)
       Post #: 33

NEED HELP!!! Scratch-building a V-22 Osprey - 6/18/2002 2:52:14 AM   
v22


 

Posts: 85
Joined: 2/24/2002
From: howe, IN, USA
Status: offline 		The real v-22 uses helicoter swash plate with cyclic controls to hover and then locks them out somewhere between heli and airplane mode.

It actually does use LARGE airplane props. They are as long and wide as a heli blade ,BUT are twisted (47 degs) and tappered just like an airplane blade so as to deal with the forward flight drag that philly mentioned .

I have tried twin vectored ( differential tilting ) engines on the wing of a light airplane and can tell any one that wants to try ,that it will not hover in ground effect good enough to take off and land like a true VTOL.Balance is a big problem on it between hover and forward flight .Now if you just want to jump into the air and thump back down into a landing then you have a cheap VTOL.

I don't consider it a vertical take off and landing aircraft unless it can hover in ground effect for several minutes with out touching the ground and then be able to convert to airplane flight and back to a serveral min. hover and then land gently.

I think that a true VTOl is what Noah is trying to build not just a funfly twin engine plane.

(in reply to Noah-Moore)
       Post #: 34

First Prop tests - 6/24/2002 11:22:00 PM   
Noah-Moore


 

Posts: 101
Joined: 4/23/2002
From: San Francisco, California
Status: offline 		Yesterday I recieved my 16X8 prop. I want to test a normal prop instead of a heli one first - i guess i'm just stuborn like that : . I don't have any flight motors or batteries yet, so i just attached it to a Dumas 12volt boat motor with a 12V battery just to see what kind of thrust this huge prop could produce. While it wasn't enough to actually lift I can tell with a gearbox and a actual airplane motor this thing will make PLENTY of thrust. The dust was flying off my workbench! But the best part was the sound - man that's nice.


HOWEVER, MinnFlyer is correct, a prop this big does act like a gyro. Holding it in my hand, i could feel it constanly wanting to return to a "neutral" position. One thing I did notice though, was that the gyro effect only lasts till it get's to about 45 degrees. So, when i'm holding in in a hover postion and i start to move to airplane mode, it is difficult to move till you get to 45 degrees then after that it moves easily to the horizontal postion. But it didn't feel as though it would be strong enough to rotate an entire fuse. Maybe that's because it was spinning relitively slowly compared to what it would be doing in actual flight - i don't know. At current, i just dont see this being able to rotate a 5 pound fuse. We'll see.

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If somebody tells you, "you can't do it", prove them wrong!

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NEED HELP!!! Scratch-building a V-22 Osprey - 6/25/2002 12:17:03 AM   
MinnFlyer



Posts: 19353
Joined: 4/22/2002
From: Willmar, MN, USA
Status: offline 		Ahhh, now consider this...

Is it strong enough to rotate a Zero lb fuse? Because that is essentially what you are rotating... 2.5 lbs forward of the nacelles, and 2.5 lbs aft.

As long as you're doing tests, try this... Balance a fuselage on something like the back of a chair. Now see how much force it takes to push the nose or tail down.

Oh, and add one more thing to the equation...
A vertical lift aircraft, while in hover, generates a high-pressure "bubble" of air directly underneath itself. And until a sufficient altitude is reached, the craft wants to "fall off the bubble". Think of it as you, standing on a 5 foot diameter ball in a swimming pool. Just ask the Heli guys. They will tell you all about the bubble.

_____________________________

Mike B.
AMA# 42400 www.gettingairborne.com

"Those are my principles. If you don't like them, I have others." - Groucho Marx

(in reply to Noah-Moore)
       Post #: 36

NEED HELP!!! Scratch-building a V-22 Osprey - 6/25/2002 1:37:19 AM   
Noah-Moore


 

Posts: 101
Joined: 4/23/2002
From: San Francisco, California
Status: offline 		Your right, i didn't remember that the fuse is essentially weightless in this type of aircraft.

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If somebody tells you, "you can't do it", prove them wrong!

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NEED HELP!!! Scratch-building a V-22 Osprey - 6/25/2002 6:19:14 AM   
Noah-Moore


 

Posts: 101
Joined: 4/23/2002
From: San Francisco, California
Status: offline 		I've been considering this for a while, but have just now decided to bring this up. I know it not really scale but couldn't i use a air-jet system to control the movement while in hover (just like a harrier does). The holes could be kept small and would not ruin the scale appearance. It just seems like this is really the only way to control a model like this feasibly. A plus is the control surface and the jet could work simultaneously, thus eliminating the need for different flight modes on the radio. While in hover, the control surface would move, but obviously, the jet would be doing all the work. Vice versa in forward flight.

P.S. this could also help fight the "gyro effect"

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If somebody tells you, "you can't do it", prove them wrong!

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       Post #: 38