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Old Oct 07, 2012, 07:40 AM
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Hover test looks good. Got to let that bird out and set it free

Be interesting to see how well it works, especially at slow speeds. I'm thinking you might have to land a little faster is all since all your commands will propel you forward a little bit.

Also curious how good pitch will be since the fans aren't spaces as far from the fuselage as the yaw commands will be in forward flight.
Here is what I'm expecting for flying characteristics:

Hovering and fast hovering ( up to about 45 fan tilt) no big deal...just a quad with an airframe on it's back.

Forward flight at low speed, the Tx "roll" inputs will produce fan "yaw" reactions with the fans tilted forward which is fine at slow and medium speed for a swept wing or wing with dihedral or very low aspect ratio wing; not so good for an anhedral wing like that on a scale Harrier. Yaw Tx inputs should have little effect with the fans tilted forward. Pitch control will probably become slower and slower as the fans become more tilted forward at all flight speeds with my arrangement.

Forward flight at high speed, I think the control of all axis become more marginal as fan tilt increases. An elevator and aileron will probably be needed for good high speed control. But.... that us what this experiment is about. How far can I go with fan control only.

If the experiment is successful; and I like the plane; I will probably add a control surface or two for high speed flying.

Hoping to do some flying this evening if I get everything done.
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Old Oct 07, 2012, 02:50 PM
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Flight report

Hover was really smooth and easy.

Fast hover (45 degree fan tilt) is easy too, I even pulled off loops and rolls in fast hover.

Forward flight was pretty good but a little different from a normal fixed wing. Because it is gyro controlled there is no "trim speed". The plane just stays pretty much where you point it. Takes a little getting used too, but no big deal. I pulled off one loop in forward flight mode. It was a pretty big loop but no problem.

I had 3 flights and several transitions on a 1000mAh 3s battery.

The only issue so far is that the big forward fuse messes up the yaw when flying fast. Coming out of the loop in forward flight the nose was even flexing to one side a bit. I plan cut the fuse down.

One cool thing is that you can be at a weird attitude and by flipping the switch back to hover or fast hover you can correct from a position where flying surfaces wouldn't be of help.

My camera crew just got home from shopping so I'll see if I can go back out and get some video.
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Old Oct 07, 2012, 03:40 PM
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Hi,

How was the pitch control in fast forward? In which way the yaw was "messed" up, as you say?

Thanks for this experiment, very helpful. I am also trying to make VTOL, as simple as possible (with minimal number of servos), using MultiWii, with minimal or no change in software. Also, trying to concentrate on tricopter, but not necessarily.
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Old Oct 07, 2012, 03:52 PM
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It would be very good to know how much is the flight time extended in forward flight compared to hover. In other words, how much the extra lift from the wings eases up strain on the battery?
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Old Oct 07, 2012, 05:12 PM
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Hi,

How was the pitch control in fast forward? In which way the yaw was "messed" up, as you say?

Thanks for this experiment, very helpful. I am also trying to make VTOL, as simple as possible (with minimal number of servos), using MultiWii, with minimal or no change in software. Also, trying to concentrate on tricopter, but not necessarily.
Pitch was pretty good in fast forward just a little slower ... which is fine when going faster.

With too much vertical surface area ahead of the cg the plane will yaw in the wrong direction in a turn. Example roll left, the nose causes the plane to yaw right.
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Old Oct 07, 2012, 06:45 PM
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Some video.

Hover Jet Experiment, Maiden (2 min 27 sec)
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Old Oct 07, 2012, 07:03 PM
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Saw the video and immediately came here looking for this thread. Interesting concept and nice work!
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Old Oct 07, 2012, 07:48 PM
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Some video...
Nice job! Looks like it handles very well.
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Old Oct 07, 2012, 11:43 PM
DIY Mania from Taiwan
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That is a great outdoor maiden flight
how's the wind condition during the flight of the day?
best regards
Sam
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Old Oct 08, 2012, 08:45 AM
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That is a great outdoor maiden flight
how's the wind condition during the flight of the day?
best regards
Sam
There was a light wind coming from the West ( from the left in most of the video), about 8 mph.

On the earlier flights I the plane did not quiver in hover. Looks like I need to dial down the gain in the gyros a bit.

I'm going to try mixing elevator to the tilt servo too; in the TX . This will allow greater tilt forward and still have pitch authority to pull out of dives.

Will probably add landing gear too and try some conventional take offs.

I was pleased at the speed of the jet even with only 45 degree fan tilt. Good enough for indoor and park flying really. But I want to see how far I can push this concept.

I do like that I don't have to write code. On my past projects I spent more time coding ( with cass's help) then building.
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Old Oct 08, 2012, 09:11 AM
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Hi,

How was the pitch control in fast forward? In which way the yaw was "messed" up, as you say?

Thanks for this experiment, very helpful. I am also trying to make VTOL, as simple as possible (with minimal number of servos), using MultiWii, with minimal or no change in software. Also, trying to concentrate on tricopter, but not necessarily.
Thanks for this experiment, very helpful. I am also trying to make VTOL, as simple as possible (with minimal number of servos), using MultiWii, with minimal or no change in software. Also, trying to concentrate on tricopter, but not necessarily.

Below is one arrangement that could work for a minimal tricopter based VTOL. You only have to tilt the front fans which simplify things a bit more.
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Old Oct 08, 2012, 09:19 AM
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Nice design, video was a blast to watch!
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Old Oct 08, 2012, 03:08 PM
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Yes, I was thinking of something similar. This one is the most likely candidate, I have to think of some wings.

Nice video and nice flying!

Quote:
Originally Posted by leadfeather View Post
Thanks for this experiment, very helpful. I am also trying to make VTOL, as simple as possible (with minimal number of servos), using MultiWii, with minimal or no change in software. Also, trying to concentrate on tricopter, but not necessarily.

Below is one arrangement that could work for a minimal tricopter based VTOL. You only have to tilt the front fans which simplify things a bit more.
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Old Oct 09, 2012, 07:17 PM
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Cut down fuse shown and now landing gear added. I'm hoping to try conventional take off tomorrow evening.

I tried mixing in tilt to elevator in the Tx, but with the servo slower I was getting strange results.
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Last edited by leadfeather; Oct 10, 2012 at 07:20 AM.
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