Need expert opinion.. - Page 2

GaryGress_1 · Oct 29, 2009, 09:53 AM

Hi,

Saw that my name was mentioned, so had to show you this:

VTOL Vector 450 Indoors and Out - Gress Aeronautics (0 min 58 sec)

a video of the Vector 450 bi-prop. It's a descendant of the MicroVader prototype that V22 referred to. Yes, it has been almost 10 years

Pitch control is obtained by having the props tilt in a direction 45 deg. from the longitudinal (fore-aft). Single-axis tilting (not gimballed), so it's still fairly simple mechanically. What's difficult and costly is the 3-axis gyro and mixer unit. You can see everything at my website, at

http://www.gressaero.com

Plans are no longer available, but complete kits are.

Gary

PS. mine is only one solution ... and it took a LONG time to develop. VTOL stability is a difficult field, so don't expect good results with new ideas right away.

v22chap · Oct 29, 2009, 12:49 PM

Gary
Hey good to see you are still around these sites .... Been to long since we really have talked and to much water over the damn ???

Hope all is going good with your venture and family ... will pm you with what I am doing at present

Larry

yuzri1984 · Oct 31, 2009, 07:50 AM

hey guys.. its me again.. first thing first... HELP!!! look at my video and ull understand why.. is it due to differences in rpm between the two motor? we got our cg done rite, now its yaw-ing like mad.. dats the reason i don't dare to throttle up more..

Vtol unstable (0 min 14 sec)

vtol unstable II (0 min 13 sec)

RCvertt · Oct 31, 2009, 08:46 AM

Quote:

Originally Posted by yuzri1984

...now its yaw-ing like mad..

The second video actually didn't look too bad except for the yaw.

Tilt the motors slightly to compensate for the yaw.

If everything is still held together with tape still, especially the rod that the motors are attached to, then you have to start securing things better. Glue some of these Landing Gear Wheel Stoppers to your fuselage to hold the motors rod. Make sure your plane balances left to right as well.

Quote:

Originally Posted by GaryGress_1

...Saw that my name was mentioned...

And purchase one of Garys kits to learn from

Something I plan to do as well.
This guy is a genious!

v22chap · Oct 31, 2009, 09:15 AM

O.K. to stop the yaw ,,, one motor has to point forward a little and the other backwards a little (engine vectoring ) .. You could play around with this in a manual position setup until you get it close ,,,but every time the motors advance or a gust of wind hits it ,,things will change .. Therefore ,,,since you aren't going to go with Greg's tri copter setup you need to follow another guys plans , Vtolman used just two motors to control VTOL flight and up close to conversion ,,,, but this will need to have TWO servos ,a vtail mixer and gyro's to control it .

These two servos and a vtail mixer / with gyro's to do pitch and yaw axis through the two motors in a true engine vector setup and balance will be touchy on this as well .

.
Please read his article as it will help you a lot .

You need to read the whole thing to get it all ...but if you skim just vtolmans posts you will get most of it . .

http://www.rcgroups.com/forums/showthread.php?t=440470

By the way ,, don't let the first pages stop you ... he starts out with vane control under the motors ,,but soon finds that he doesn't need the vanes and takes them off and still flys well

Middle of page 5 Vtolman gives the specs to his bird ... :

http://www.rcgroups.com/forums/showt...=440470&page=5
motor size and esc / props etc.

Good luck ,,, hope this helps some .

v22chap · Oct 31, 2009, 09:50 AM

Here are a few pix

I am trying to get the videos up ,,but this new layout that they have don't accept the video files any more , and it erased the ones I had loaded yrs ago when he did this ,,will try to get them up on youtube I guess

v22chap · Oct 31, 2009, 10:11 AM

Here come the videos ;;; first how his controls work .

kingsleyscontrols (0 min 7 sec)

v22chap · Oct 31, 2009, 10:16 AM

flying in his living room

kingsleycircleslivingroom (0 min 8 sec)

v22chap · Oct 31, 2009, 10:18 AM

And outside and does a loop

Kingsleysvtoldoesloop (0 min 26 sec)

v22chap · Oct 31, 2009, 10:21 AM

Hope these help you ,,,, good luck

F-111 John · Nov 02, 2009, 07:22 AM

Quote:

Originally Posted by yuzri1984

hey guys.. its me again.. first thing first... HELP!!! look at my video and ull understand why.. is it due to differences in rpm between the two motor? we got our cg done rite, now its yaw-ing like mad.. dats the reason i don't dare to throttle up more..

Nevermind, I see from post #1 that they are.

v22chap · Nov 02, 2009, 12:24 PM

F111
That is o.k. as it wouldn't have made any difference as the only controls he has on it right now is motor ESC's ... and not sure ,,but maybe a vtail mix on throttle for roll control ....
It aint going to happen until he gets rudder and pitch controls on there and then it will be minimal at least .

But he is learning and the best way ... try it and find out

tungym · Nov 07, 2009, 01:40 PM

It still suffers from the tip over problem (pendulum effect) with a bi-prop design. You can see from the Discovery Channel video link. I think it might have solve the problem, but it doesn't.

It is like a seesaw as the lift is close to the C.G. itself , nothing is goona dampen the pendulum.

yuzri1984 · Nov 08, 2009, 09:29 AM

so is it i have increase the length of the rod where my motor sits on?

Brandano · Nov 08, 2009, 09:55 AM

it doesn't matter how far the motor is from the pivot point, what matters is how far is the pivot point from the CG. the bigger the control arm, the greatest the control authority. But don't think for one second that this will make the plane more stable, it will only make the control inputs more effective. You have to think in terms of vectors of thrust and vector of gravity, remembering to take into account all vector components. The "pendulum effect" is an illusion, a plane can't hang from its prop because the prop tilts with the plane. You need something else there to keep it upright. Quick thumbs or some form of stabilization system, like hiller paddles.

Oct 31, 2009, 09:15 AM	#20
v22chap Registered User Join Date: Jan 2003 Location: Goshen, Indiana, United States Posts: 1,991	O.K. to stop the yaw ,,, one motor has to point forward a little and the other backwards a little (engine vectoring ) .. You could play around with this in a manual position setup until you get it close ,,,but every time the motors advance or a gust of wind hits it ,,things will change .. Therefore ,,,since you aren't going to go with Greg's tri copter setup you need to follow another guys plans , Vtolman used just two motors to control VTOL flight and up close to conversion ,,,, but this will need to have TWO servos ,a vtail mixer and gyro's to control it . These two servos and a vtail mixer / with gyro's to do pitch and yaw axis through the two motors in a true engine vector setup and balance will be touchy on this as well . . Please read his article as it will help you a lot . You need to read the whole thing to get it all ...but if you skim just vtolmans posts you will get most of it . . http://www.rcgroups.com/forums/showthread.php?t=440470 By the way ,, don't let the first pages stop you ... he starts out with vane control under the motors ,,but soon finds that he doesn't need the vanes and takes them off and still flys well Middle of page 5 Vtolman gives the specs to his bird ... : http://www.rcgroups.com/forums/showt...=440470&page=5 motor size and esc / props etc. Good luck ,,, hope this helps some . Last edited by v22chap; Oct 31, 2009 at 10:26 AM.

Oct 31, 2009, 09:50 AM	#21
v22chap Registered User Join Date: Jan 2003 Location: Goshen, Indiana, United States Posts: 1,991	Here are a few pix I am trying to get the videos up ,,but this new layout that they have don't accept the video files any more , and it erased the ones I had loaded yrs ago when he did this ,,will try to get them up on youtube I guess Last edited by v22chap; Oct 31, 2009 at 10:20 AM.

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Oct 29, 2009, 12:49 PM	#17
v22chap Registered User Join Date: Jan 2003 Location: Goshen, Indiana, United States Posts: 1,991	Gary Hey good to see you are still around these sites .... Been to long since we really have talked and to much water over the damn ??? Hope all is going good with your venture and family ... will pm you with what I am doing at present Larry

Oct 31, 2009, 10:21 AM	#25
v22chap Registered User Join Date: Jan 2003 Location: Goshen, Indiana, United States Posts: 1,991	Hope these help you ,,,, good luck

Nov 02, 2009, 12:24 PM	#27
v22chap Registered User Join Date: Jan 2003 Location: Goshen, Indiana, United States Posts: 1,991	F111 That is o.k. as it wouldn't have made any difference as the only controls he has on it right now is motor ESC's ... and not sure ,,but maybe a vtail mix on throttle for roll control .... It aint going to happen until he gets rudder and pitch controls on there and then it will be minimal at least . But he is learning and the best way ... try it and find out

Nov 07, 2009, 01:40 PM	#28
tungym Registered User Join Date: Jul 2005 Location: Planet Earth Posts: 632	It still suffers from the tip over problem (pendulum effect) with a bi-prop design. You can see from the Discovery Channel video link. I think it might have solve the problem, but it doesn't. It is like a seesaw as the lift is close to the C.G. itself , nothing is goona dampen the pendulum.

Nov 08, 2009, 09:29 AM	#29
yuzri1984 Registered User Join Date: Oct 2009 Posts: 7	so is it i have increase the length of the rod where my motor sits on?

Nov 08, 2009, 09:55 AM	#30
Brandano Registered User Join Date: Oct 2004 Posts: 1,385	it doesn't matter how far the motor is from the pivot point, what matters is how far is the pivot point from the CG. the bigger the control arm, the greatest the control authority. But don't think for one second that this will make the plane more stable, it will only make the control inputs more effective. You have to think in terms of vectors of thrust and vector of gravity, remembering to take into account all vector components. The "pendulum effect" is an illusion, a plane can't hang from its prop because the prop tilts with the plane. You need something else there to keep it upright. Quick thumbs or some form of stabilization system, like hiller paddles.