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Old Nov 19, 2010, 12:43 AM
Registered User
Madison, MS
Joined Oct 2006
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Thrust Vectoring Kite

Will it work? Might find out tomorrow.

Massive 102in. Stunt kite

http://www.mcgillswarehouse.com/k44-...kite-102x30-u1

Scratch built thrust vector gimbal.
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Old Nov 19, 2010, 05:35 AM
Old age is not for sissies
Azarr's Avatar
Dayton Intl, Ohio, United States
Joined Jan 2000
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If you have the cg right it will work well. I'v seen quite of the Premier kites. I particularly their diamond although they're pretty expensive. I've tried on more than one occasion to get them to sell the gimbal separately, but they don't seem interested.

Azarr
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Old Nov 19, 2010, 06:25 AM
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KenChin's Avatar
Kuala Lumpur, Malaysia
Joined Aug 2006
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I've tried making the box kite once... but i aborted the project as i need to use the CF tubes.

But i kept the Vector Unit, just in case in the future, you know...

I am watching this thread...
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Old Feb 10, 2011, 03:31 PM
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Madison, MS
Joined Oct 2006
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i got really busy over the holidays but i finally got around to slapping it together and believe it or not it works. i flew it a very short distance in my back yard and can't wait for some better weather and really calm winds to try it out in the open.

got a few things to perfect and i'll try to get a video up soon.
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Old Feb 11, 2011, 01:23 AM
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KenChin's Avatar
Kuala Lumpur, Malaysia
Joined Aug 2006
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Hey! It's me again... i've revived the old thrust vector i had in to a cheap delta kite and it flow flawlessly !

However, a ne trick is learned, that it only steers with throttle on! Mine requires quite a fair amount of up thrust maybe my unit is too far front of the kite. But otherwise... i am happy at this moment.

Here are some photos.
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Old Feb 11, 2011, 01:59 AM
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Whiskers's Avatar
Australia, QLD, Little Mountain
Joined Feb 2010
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It will require a good bit of up-thrust due to the high thrust-line. For the same reason it will want to dive during acceleration.
No big deal, just flight characteristics to be aware of.
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Old Feb 11, 2011, 03:06 AM
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Malaysia, Selangor, Kajang
Joined Jun 2009
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Quote:
Originally Posted by Whiskers View Post
It will require a good bit of up-thrust due to the high thrust-line. For the same reason it will want to dive during acceleration.
No big deal, just flight characteristics to be aware of.
I mentioned this on Ken's blog on malaysia-rc.com but mine actually requires a bit of downthrust for level flight. Otherwise it will tend to pitch up. I'm guessing that KenChin has a more nose-heavy kite than mine.

All my kites can fly with a fairly wide range of CG. Shifting the CG forward gives me a more level AoA and faster flight and shifting the CG back gives me a higher AoA and slower flight.
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Old Feb 11, 2011, 11:10 AM
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Madison, MS
Joined Oct 2006
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Quote:
Originally Posted by KenChin View Post
Hey! It's me again... i've revived the old thrust vector i had in to a cheap delta kite and it flow flawlessly !

However, a ne trick is learned, that it only steers with throttle on! Mine requires quite a fair amount of up thrust maybe my unit is too far front of the kite. But otherwise... i am happy at this moment.

Here are some photos.

awesome, can you post some more pics of it, maybe with it standing on its tail so we can see the top view. where is your cg? whats your weight and wingspan?
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Old Feb 11, 2011, 11:19 AM
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Madison, MS
Joined Oct 2006
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tested mine a little more this "am" in a larger field and i've noticed a couple of problems. it wants to roll one way or the other depending on if all the rigging is straight or not. i've got this figured out and got it to fly pretty straight. it has plenty of pitch authority but not enough rudder authority. i'm thinking this may be due to the lack of dihedral and the motor may be to close to the cg. currently the cg is right under the kingpost, the very back of the whole thrust vector/servo frame so it may not have a long enough arm to make it yaw, or i may not have enought throw in the controls.

lots of variables to work out.
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Old Feb 15, 2011, 12:55 PM
check the crazyplanes ...
flattermann's Avatar
Germany
Joined Dec 2006
315 Posts
Hi dpowellmeii,

don't worry about problems - vector kiting for sure is a bit 'out of the box' and needs to gain new (and very interesting) experiences. The main thing is: Trick-Kites like Yours, converted to a Vector Kite, urgently need kind of 'angle of incedence', by lifting the wing-tips, to guarantee a stable flight ability.
In another thread, hoverbovver's, link:

http://www.rcgroups.com/forums/showt...7#post17405469

I made some photo-explanations, as well regarding the appr. CoG. and -very important- the protection of the Vector Unit and a safe mode of early test flights (recommended with 'safety tail' to avoid early damages).

I attach the photo of hoverbovver (comments added) because I think, they might help You as well.
Make sure, that Your servos can stand the moving loads of the push-rods under full motor thrust in all directions, and also make sure, that the vector unit frame does'nt make unwanted moves. As Your photos show, the Wing seems to have a ' M ' - shape like the original 2-liners have. If it is so, it will not work satisfying as a vector kite -too instable - watch this video:

www.crazyplanes.de/trickkite_m_shape.avi

I took a non-modified 280cm trickkite, mounted a 'test fuselage' beyond the keelrod and started for a flight, to gain experiences to see, what would happen. Result: M-Shape is instable, V-shape is a must, to reach stuntability.

I'm sure: Your vectored trickkite will fly much more stable after a few modifications. To gain the nesessary dehidral a n d a wriklefree sail, You can use (like hoverbovver did) an exelcross with 2 spanning struts along the sail's surface, or, a 'top spanning bow' to span and stabilize strongly the whole vector unit - like the vectored trickkite has, shown in that video:

www.crazyplanes.de/bebopextreme.wmv

Have fun!

flattermann
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Old Feb 15, 2011, 12:57 PM
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Japan
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Hi dpowellmeii-
You posted on my thread with this link for help. I'll see if I can.
I'm new to this, but I think you won't be able to fly it well with that design. If you start at this post and read down, you'll see why and get a relatively detailed build log also:
http://www.rcgroups.com/forums/showp...7&postcount=31
"Flatterman" is really an expert on this stuff. Despite using the wrong equipment and being waaay too heavy, mine flys really well. Flatterman used carbon tubes, 15g metal servos, a nice kite, etc., and gets the incredible performance you see in the linked video.
Unless you're onto a new design I'm not aware of, you need to get rid of all those cross-under rods, and put a high-tension cross-bow over the top connecting with the vector unit, as shown in the link.
That looks like a nice kite and vector unit you have, I see it flying really well if you change it around.
I need to update that link with my final build and flight video.

EDIT: lol, Flatterman posted while I was typing. These kite people are really nice AND on the ball!
Just wanted to add the main variables, that will affect flight, I saw in my tests (related to the 2-line stunt kite vector conversion):

1) Motor position (vertical and horizontal) and angle.
2) CoG (vertical and horizontal).
3) Angle of Incidence (AoI).
4) Weight.
5) Rod and fabric tension.
6) Prop size.
7) Streamer tail size.
8) Dihedral.

Once you get it flying well, points 2,3,and 7 are the likely ones you can easily shift on the fly to alter performance.

In particular, moving the battery forward and back and slightly altering the AoI interacted with each other and caused huge differences in flight characteristics.

Generally speaking, I found it best to put the motor as far forward as possible to get better control.

What did you use to join the carbon rods on your vector unit?
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Old Feb 15, 2011, 01:26 PM
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Harry D's Avatar
Canada, AB, Edmonton
Joined Oct 2004
1,295 Posts
I have a question for you guys who have a bit of experience with all this neat stuff. I'm working on a gimbal design (very similar to the one by dpowellmeii, actually) and am wondering what sort of angular deflection is needed or desirable. Using the common Du-bro ball link, I can get a maximum total deflection of about 40 in two planes (plus of course much more in one plane but that doesn't help much). I can increase that to about 50 (25 each way) by chamfering the corner of the retaining cap screw head.

Is that enough deflection? If not, how do you guys get more? Any guidance or comments appreciated.

[dpowellmeii, I don't mean to hijack your thread, but I think my question is relevant to what you're doing and what is being discussed here. I don't really know where else to ask, until we get our own kites forum. Which, incidentally, is in the works.]
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Old Feb 15, 2011, 01:57 PM
check the crazyplanes ...
flattermann's Avatar
Germany
Joined Dec 2006
315 Posts
Hi HarryD,

The attached Youtube-screenshot shows a solution of around totally 50 degrees (25 into each direction).

Improvement: Instead of the ball heads shown on the photo, I always use screwable sockled ball heads (sockle around 1.5mm height, without using a separate screw going through the ball).
The sockle enlarges the range. Also make sure, that the gimbel parts are thin and curved (without loosing stability) - and not too thick.

So, You gain more space for more deflection.

Make sure, that the possible movements are not too much - otherwise, the balljoints could clip off during flight....

50degrees is enough for comfortable aerobatics - 60 degrees is more crazy ...

flattermann
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Old Feb 15, 2011, 07:30 PM
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Harry D's Avatar
Canada, AB, Edmonton
Joined Oct 2004
1,295 Posts
Thanks for the information, flattermann. So 50 should be enough for what I want to do (mild aerobatics only). Good to know.

The ball links I've been trying to use are these http://shop.dubro.com/products/produ...3.0.0.0?pp=10&
which I think are the same ones used in the video you show.

I also tried this style
http://shop.dubro.com/products/produ...3.0.0.0?pp=10&
but they were not nearly as free-moving or smooth operating as the ones with the screw through the ball. Also they had no greater angle of deflection. Is this style what you mean by "sockled" [socket]?

Maybe you (or others!) know of a source for better quality ball links. Of course, these are pretty basic items for all our vector kites, so if you have and would care to post more information about them (including things like brand names and sources) I'm sure a lot of us would find that very useful in the future. Thanks!
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Old Feb 15, 2011, 08:12 PM
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Malaysia, Selangor, Kajang
Joined Jun 2009
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Quote:
Originally Posted by Harry D View Post
Thanks for the information, flattermann. So 50 should be enough for what I want to do (mild aerobatics only). Good to know.
Also, the further forward the motor is from the CG the less deflection you need.

My design has roughly 90 total deflection (40-45 per side) and my old vector unit needed that. I've just built a new vector unit which puts the motor around an inch and a half forwards of its old position and found that I barely need to use a quarter of the total deflection to do tight turns. I now find that I keep over-correcting my over-corrections. Got to reduce my servo throws a bit (or just learn to get used to it).
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