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Jan 28, 2016, 08:30 AM
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leadfeather's Avatar
Alex, what prop and esc were you using with the DT750's? Also what is the approximate flying weight of the V2 ship?

Dan
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Jan 29, 2016, 11:24 AM
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hoiberg42's Avatar
Quote:
Originally Posted by leadfeather
Alex, what prop and esc were you using with the DT750's? Also what is the approximate flying weight of the V2 ship?

Dan
Prop: 10x4.5 SF

Fuselage weight: 243g
Wing set weight: 715g
Battery weight: 191g
Total: 1149g

The ESC's are HobbyKing 20A w/ 3A UBEC. I planned to flash them with simonK, but I still haven't done that :P

By the way, I'll post my KK2 settings once I have flown the V2.
Jan 29, 2016, 05:24 PM
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leadfeather's Avatar
Here is one test done by Mortimer comparing different props on the DT 750.

Based on this data, it looks like you may be close to the maximum attainable pitch speed while still being able to hover on 3s for the DT 750.

So; if you want more speed for forward flight; which adds less weight. 4s battery or stronger motor or variable pitch prop??

.
Last edited by leadfeather; Jan 29, 2016 at 05:30 PM.
Jan 30, 2016, 08:50 AM
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hoiberg42's Avatar
Quote:
Originally Posted by leadfeather
Here is one test done by Mortimer comparing different props on the DT 750.

Based on this data, it looks like you may be close to the maximum attainable pitch speed while still being able to hover on 3s for the DT 750.

So; if you want more speed for forward flight; which adds less weight. 4s battery or stronger motor or variable pitch prop??

.
Tomstanton used a SunnySky x2216-8 1250kv for his V22, and I was thinking that if I would buy a new motor (which I probably won't) I would choose something similar. It is more expensive, but weights 10g less and produced a lot more thrust:

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But the nicest solution of all would be (of course) to use the blades & motor mechanism out of a HK250!
Apr 23, 2016, 06:46 AM
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hoiberg42's Avatar
Update!! It has had its maiden! And it's still in one piece
The footage is of low quality though. I'll try to get hold of a better camera w/ tripod the next time.

RC V22 Osprey v2 - VTOL flight testing #1 (1 min 21 sec)

RC V22 Osprey v2 - VTOL Flight testing #2 (1 min 46 sec)

RC V22 Osprey v2 - VTOL Flight testing #3 (2 min 56 sec)


I have updated the article with information on the flight characteristics and the OpenAeroVTOL settings.
I wrote the following:

Quote:
Hovering: It is quite stable and flyable in hover mode. At least, it is until it will suddenly point the noise vertically downwards and starts falling. With enough height, it will recover automatically but there was close call at the end of the video #2. What causes this, you ask? Maybe it’s the PID’s, maybe it was the wind pushing the bulky nose down, or maybe it’s preventable. I’m not sure.

Transitioning: The transition to fast forward flight is very uneventful, you have more than enough authority over the pitch the whole time.

Forward flight: It has plenty of power during hover flight, yet it feels underpowered in forward flight (near-stalling the whole time). But it *is* flyable It was a bit unstable on the roll axis, which can probably be solved by adjusting the aileron throws.

In between HF and FF: The Osprey actually flies best in between hover flight and fast forward flight. It feels a lot more responsive and predictable. In fact, enough to make me confident enough to fly a couple of low level circles (in video #3).
Apr 23, 2016, 07:26 AM
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Great work, it looks the part!.
Nick.
Apr 24, 2016, 12:38 PM
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Ran D. St. Clair's Avatar
Congratulations on a successful build.

Never ever try to fly that thing backwards, and that includes hovering tail into the wind.

If it pushes the nose down when hovering into the wind then I suggest setting your hover setting on your TX to P1.1 or so. That will give you some ability to penetrate without having to push the nose down. It will also move you part way into the more stable SFF mode.

The problem with just being able to fly at full throttle in FFF has to do with the low pitch speed of the props and the small wing area. Experiment with slightly higher pitch props. You may have to reduce the diameter to keep from overheating the motors. Higher pitch props will generate less thrust in hover and draw more current doing it, so that is the trade off you have to make. As you can fly a little faster in FFF with a lower throttle setting it will be considerably more efficient.
Apr 25, 2016, 08:47 AM
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hoiberg42's Avatar
Quote:
Originally Posted by Shorty
Great work, it looks the part!.
Nick.
Thanks


Quote:
Originally Posted by Ran D. St. Clair
Congratulations on a successful build.

Never ever try to fly that thing backwards, and that includes hovering tail into the wind.

If it pushes the nose down when hovering into the wind then I suggest setting your hover setting on your TX to P1.1 or so. That will give you some ability to penetrate without having to push the nose down. It will also move you part way into the more stable SFF mode.

The problem with just being able to fly at full throttle in FFF has to do with the low pitch speed of the props and the small wing area. Experiment with slightly higher pitch props. You may have to reduce the diameter to keep from overheating the motors. Higher pitch props will generate less thrust in hover and draw more current doing it, so that is the trade off you have to make. As you can fly a little faster in FFF with a lower throttle setting it will be considerably more efficient.
That's some great advice! Thank you very much indeed!
I did notice with the V22V1 that it just wouldn't fly backwards or (as you predicted as well) with the tail in the wind. I wonder why that is though. Could it be the deflected flaperons generating downforce, or the h&v stabilizers acting destabilizing?
Apr 25, 2016, 10:25 AM
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Ran D. St. Clair's Avatar
Quote:
Originally Posted by hoiberg42
Thanks




That's some great advice! Thank you very much indeed!
I did notice with the V22V1 that it just wouldn't fly backwards or (as you predicted as well) with the tail in the wind. I wonder why that is though. Could it be the deflected flaperons generating downforce, or the h&v stabilizers acting destabilizing?
Flying backwards is aerodynamically divergent. The tail will drop, and the negative angle of attack will generate negative lift, causing the tail to drop some more... The end result is what I call a "flop loop" where the aircraft tumbles backwards. It can be fun to do with adequate altitude as the aircraft will recover in a dive.

Most VTOL aircraft will do this, but your aircraft, by its nature, has very limited pitch authority. It is unable to fight off hardly any negative lift from the tail and the divergence will quickly proceed beyond your control.

The wing and flaps have little to do with it, since they are close to the CG and have very little lever arm. The horizontal stabilizer has lots of lever arm though.

Flying backwards is vaguely similar to flying forwards with a massively tail heavy airplane. What ever way it starts to go, it's going to go in a big way.
May 14, 2016, 10:39 AM
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hoiberg42's Avatar
More videos!

RC V22 Osprey - VTOL flight testing #4 (3 min 14 sec)

RC V22 Osprey - VTOL flight testing #5 (3 min 40 sec)

RC V22 Osprey - VTOL flight testing #6 (3 min 21 sec)


Also, I have now added roll stabilization in forward flight mode. This improved the stability considerably.
May 14, 2016, 12:29 PM
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RCvertt's Avatar
Nice job there.
May 14, 2016, 01:58 PM
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Ran D. St. Clair's Avatar
You should be proud.
May 14, 2016, 02:27 PM
Winging it >
leadfeather's Avatar
Thmbs up! Great job!
Jan 09, 2017, 12:20 AM
Aka "DiveBomb"
Great Job! I just came across your build, and this was awesome to see and gave me a great bench fly here in New England with all the snow we got yesterday!

I'm looking forward to finally building a VTOL, thanks for the inspiration!

Any plans for the winter for a V3?
Jan 09, 2017, 02:37 AM
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hoiberg42's Avatar
Quote:
Originally Posted by jk6stringer
Great Job! I just came across your build, and this was awesome to see and gave me a great bench fly here in New England with all the snow we got yesterday!

I'm looking forward to finally building a VTOL, thanks for the inspiration!

Any plans for the winter for a V3?
No plans for a V3 as of yet. Too many other unfinished projects


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