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Old Oct 11, 2012, 12:49 PM
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United States, VA, Mechanicsville
Joined Oct 2006
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Thrust Vectoring - Tractor Propeller

I've been working on an idea for a VTOL vehicle for sometime now while I have been building a a Y6 600mm heavy lift Multi. It's done now...

Does anyone have any experience or info (or...) with regard to Thrust Vectoring from the Front of a vehilce with a propeller. Could a craft be flown by thrust vectoring a prop in the front? I have seen a lot of ideas where the craft vectors thrust with the rudder axis, but not both.

thanks,
Laszlo
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Old Oct 11, 2012, 05:04 PM
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Ursel, Belgium, Europe
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http://www.crazyplanes.de/

his vector kites and 3D-Zugvektorsteuerung-planes.


Dirk.
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Old Oct 11, 2012, 05:12 PM
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Thanks, I did find the vector kites, I was looking for something larger.
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Old Nov 25, 2012, 06:03 PM
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Skate UAS

Here is a craft that uses tractor thrust vectoring. The two motors are tiled for pitch control. Differential trust is used for steering. There are NO control surfaces that move on this version and this fact is shown in the video too, but if you open the attached PDF you'll see two versions, one version has an elevator the other version does not.

Also note that the electric motors are attached to the control arms of servos to tilt the motors, perhaps in the manner that is used for elevons. These servos are held in place with magnets, allowing them to be knocked off in a rough landing and allowing the craft to fold up much like a map for transportation. This a very sophisticated aircraft designed by a well funded company, but many aspect could easily be incorporated into the average modelers needs

Here is a great detailed video showing details of it construction and flight operations:
http://www.engineeringtv.com/video/S...rospaceDefense

Look here at the manufactures website photo gallery: http://www.aurora.aero/Media/Gallery/Skate.aspx

Attached is a detailed PDF of the Skate

Kelly
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Last edited by corocopter; Nov 25, 2012 at 07:08 PM.
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Old Nov 25, 2012, 07:43 PM
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Vortex Induced Lift

I should add that this craft utilizes " Vortex Induced Lift". This allows the craft to fly at a very high angle of attack, as high as 45 degrees, the vectored thrust augments this capacity allowing even higher angles of attach, thus achieving very slow flight conditions

Vortex lift is found on very low aspect wing forms most notable is the Delta form or the Square form, you may recall the Pizza Box Flyer design which is a perfect example of what the Skate resembles. Two strong vortexes are created by the sharp square pointed wing tips. These vortex swirl over the top surfaces creating a spinning mass of air that creates a strong low pressure region.This low pressure accounts for the low speed characteristics of these wing forms.

Sir Handley Page discover this fact about a square wing form around 1920-1921.The square wing form is most often over-looked when vortex lift is described in aeronautical literature, and has been rediscovered many times in recent years by designers working on small MAV/UAV craft, and stumbled upon by modelers i.e. PBF spad aircraft around 2003.

See attached photo of a delta wing form vortex, a square wing form looks the same.

Also reference Wiki here for vortex lift. http://en.wikipedia.org/wiki/Vortex_lift

Kelly
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Old Nov 25, 2012, 07:51 PM
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Very interesting, thanks.

Laz
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Old Nov 25, 2012, 08:04 PM
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Flyswatter

The Flyswatter

Here is another Square wing form design from Dr. Steven Morris of MBL.

Please look at page 11, figure 7. for a drawing of the craft and vortex attached to the upper surfaces.

The clip below from the PDF is indicating surprise at discovery of the vortex lift and gives an excellent discription of the problems of lateral control. The Skate overcame this problem by having two motors, using differential thrust and no control surfaces and it killed the lateral wobble by blasting the vortex with prop wash.

Clip from the PDF below.....


An unexpected advantage of the Flyswatter’s low aspect ratio planform is
the development of vortex lift at high angles of attack as shown in figure 8. This allows the model to turn
much tighter than expected and to fly as slowly as 20.0 fps (CLmax =1.7 ). Low aspect ratio along with a
"high" wing loading of 0.8lb/ft2 decreases the μAV’s gust sensitivity and the Flyswatter can be flown in
winds up to 15 mph. Rudder and elevator surfaces are used to control the μAV and the rudder is particularly
sensitive due to the high velocity propellor wake that impinges on it. The airflow over the wing is
dominated by the vortical flow for lift coefficient above 0.2 and it is the strength of these vortices that
determine the control power of the rudder through sideslip-roll coupling. This causes the rudder authority to
vary considerably with trimmed lift coefficient and also leads to a wing-rock limit cycle motion at high
angle of attack. Experimenting with larger vertical tail surfaces and adding an active control system would
further improve the handling qualities. Initial versions of the Flyswatter used ailerons for roll control, but
they proved to be ineffective due to the strong vortical flow at the wing tips. Rudder control provides more
than adequate roll authority through sideslip-roll coupling so long as the lift coefficient of the wing is positive. A typical flight profile involves hand-launching the μAV, climbing to 50 feet altitude and then
performing reversal turns every 50 - 100 feet in order to keep the aircraft in visual contact. When the fuel
runs out the Flyswatter is glided in for landing. The vehicle is strong enough to survive full-power crashes
into a grass field without damage because of its small weight and size.
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Old Jan 19, 2013, 03:45 AM
1400 watt RW Zephyr
matwelli's Avatar
Taranaki New Zealand
Joined Sep 2003
1,333 Posts
Quote:
Originally Posted by Lazman View Post
I've been working on an idea for a VTOL vehicle for sometime now while I have been building a a Y6 600mm heavy lift Multi. It's done now...

Does anyone have any experience or info (or...) with regard to Thrust Vectoring from the Front of a vehilce with a propeller. Could a craft be flown by thrust vectoring a prop in the front? I have seen a lot of ideas where the craft vectors thrust with the rudder axis, but not both.

thanks,
Laszlo
like this ?

shaft copter (1 min 47 sec)
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Old Jan 19, 2013, 06:18 AM
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Interesting... The trust center and cg are pretty far apart.

Laz
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Old Jan 19, 2013, 08:58 AM
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Quote:
Originally Posted by Lazman View Post
I've been working on an idea for a VTOL vehicle for sometime now while I have been building a a Y6 600mm heavy lift Multi. It's done now...

Does anyone have any experience or info (or...) with regard to Thrust Vectoring from the Front of a vehilce with a propeller. Could a craft be flown by thrust vectoring a prop in the front? I have seen a lot of ideas where the craft vectors thrust with the rudder axis, but not both.

thanks,
Laszlo
Yes, it can. I have scratch built and have flown "Eyespy" which is the earlier version of Skate. Not having any movable control surfaces didn't help with finding the CG. Thrust vectoring really had to be toned down to make it fly.
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Old Jan 19, 2013, 09:11 AM
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https://www.youtube.com/watch?v=xBAe8SgL2Mo]

Sorry for the poor quality of video, this is learning how to fly the new animal. Skate has a microchip assisting in flight, I don't. My camera hat wasn't centered.
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Old Jan 21, 2013, 03:19 AM
1400 watt RW Zephyr
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Taranaki New Zealand
Joined Sep 2003
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Quote:
Originally Posted by Lazman View Post
Interesting... The trust center and cg are pretty far apart.

Laz
thats actually critical for control,

its not the thrust centre, but pivot point of the thrust in relation to the CG that controls how much control you actually have
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Old Jan 28, 2013, 10:18 PM
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gardena, ca
Joined Feb 2003
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This VTOL seems to fly quite well. Looks very similar to the above VTOLs:
http://www.rcgroups.com/forums/showt...ying+wing+vtol
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