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Jan 25, 2016, 05:36 AM
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hoiberg42's Avatar
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Semi-scale depron V22 VTOL (with plans!)


The build of my depron V22 Osprey is finally done!
This is the second and final version of my Osprey design, and it is controlled by a KK2.1.5 flashed with OpenAeroVTOL and powered by two DT750's.

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How do you like my low viz rising sun?
More pics and specs (and the plans) can be found here.

The V1 flew great in hover flight and at about 50% between HF and FF, though it lacked lift in 100% FF. Here is a flight video:

(1 min 17 sec)


The V2 has not flown yet - I'll post an update as soon as it has!
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Jan 25, 2016, 05:43 AM
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hoiberg42's Avatar
This might interest other VTOL diy'ers:
With the V1, I did some testing with a movable battery mechanism:

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I linked it with the elevator in hover flight, and it did make it noticably more stable (it acts like a third rotor). But it was hard to get it move smoothly, and I ended up not including it in the V2.
Jan 25, 2016, 10:43 AM
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Ran D. St. Clair's Avatar
Very nice. It creates 80% of the illusion with about 10% of the work. You should be prepared for people asking for your OAV parameters. I like the old school pencil plans and I do admire your Depron building skills. You made some pretty complex shapes but it came out clean. I am surprised that it can't do full forward flight, or perhaps that was only the first version?
Last edited by Ran D. St. Clair; Jan 25, 2016 at 10:50 AM.
Jan 25, 2016, 01:00 PM
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hoiberg42's Avatar
Quote:
Originally Posted by Ran D. St. Clair
Very nice. It creates 80% of the illusion with about 10% of the work. You should be prepared for people asking for your OAV parameters. I like the old school pencil plans and I do admire your Depron building skills. You made some pretty complex shapes but it came out clean. I am surprised that it can't do full forward flight, or perhaps that was only the first version?
Thanks
The new wings have more surface area and an improved airfoil, so I have high hopes that the second version will be capable of FF.
In fact, I have already tested the new wing set, and I was able to fly one full circle in FF. This should only get better with the new fuselage.
Jan 25, 2016, 02:05 PM
Winging it >
leadfeather's Avatar
Great job hoiberg!

The DT750's might not be giving you enough pitch speed for forward flight, they are pretty low kV...good for hovering.

If it is a propeller pitch speed issue (been there myself) some things you can do...

Higher pitch prop
4s battery if your electronics will handle it
Swap out to a motor/prop combo with higher prop speed

Also making the craft capable of flying slower might help too:
Longer wings
Flying with some flaps

Looking forward to seeing more progress!!
Last edited by leadfeather; Jan 28, 2016 at 09:09 AM. Reason: changed "prop speed" to "pitch speed"
Jan 25, 2016, 02:32 PM
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hoiberg42's Avatar
Quote:
Originally Posted by leadfeather
The DT750's might not be giving you enough prop speed for forward flight, they are pretty low kV...good for hovering.
Thanks for the advice! I did not think of that. I first thought drag was the problem but this makes more sense.
Jan 25, 2016, 03:36 PM
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motorhead's Avatar
Can we get a good picture of the motor tilt?
Mike
Jan 25, 2016, 04:33 PM
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Hi,
Just wanted to say what a great model you have built and wish you every success.
Cheers,
Nick.
Jan 25, 2016, 06:28 PM
Registered User
The full size one does a neat trick with the spiralling prop wake to increase the lift it gets from its short, stubby wings. Unfortunately, in order to do that the rotors have to be on the wing tips rather than outboard of them, and their direction of rotation is the "wrong" one when compared with twin engined planes. This is not a big issue since the V22 is not meant to land conventionally and is never going to experience an asymmetric thrust situation.
Jan 26, 2016, 08:32 AM
I COLLECT flyaway&lost drones!
martin555's Avatar
looking good ! smooth.

do yourself a favor replace the bearings in the DT750.
Jan 26, 2016, 12:33 PM
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hoiberg42's Avatar
Quote:
Originally Posted by motorhead
Can we get a good picture of the motor tilt?
Mike
Here you go:

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It's very similar to the classic RCExplorer method, modified for >90 rotation.


Quote:
Originally Posted by Shorty
Hi,
Just wanted to say what a great model you have built and wish you every success.
Cheers,
Nick.
Thanks a lot!


Quote:
Originally Posted by Brandano
The full size one does a neat trick with the spiralling prop wake to increase the lift it gets from its short, stubby wings. Unfortunately, in order to do that the rotors have to be on the wing tips rather than outboard of them, and their direction of rotation is the "wrong" one when compared with twin engined planes. This is not a big issue since the V22 is not meant to land conventionally and is never going to experience an asymmetric thrust situation.
Hadn't thought of that either. The problem is that if I put the prop above the wing (well, at least half of it..) it will loose a lot of thrust in hover flight. I think.

Quote:
Originally Posted by martin555
looking good ! smooth.

do yourself a favor replace the bearings in the DT750.
Yeah.. I think I damaged one a while back. Almost forgot about that. Do you think it will make a noticeable improvement?
Jan 26, 2016, 12:56 PM
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motorhead's Avatar
I have not had any trouble with bearings in mine but I always mount the prop like in the picture above with 2 nuts. I thought allot of the bearing issue had to do with people tightening the prop against the bell which pulls on the shaft which then causes the E-clip to load the rear bearing.
Have you heard any different?

Thanks for the picture of the motor pivot.
Mike
Jan 26, 2016, 01:06 PM
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hoiberg42's Avatar
Quote:
Originally Posted by motorhead
I have not had any trouble with bearings in mine but I always mount the prop like in the picture above with 2 nuts. I thought allot of the bearing issue had to do with people tightening the prop against the bell which pulls on the shaft which then causes the E-clip to load the rear bearing.
Have you heard any different?
No, but I think I damaged the bearings some other way... don't remember exactly how.
Jan 26, 2016, 03:10 PM
Registered User
Quote:
Originally Posted by hoiberg42
...
Hadn't thought of that either. The problem is that if I put the prop above the wing (well, at least half of it..) it will loose a lot of thrust in hover flight. I think.
...
You are right, and I am not suggesting you to do that.
The full sized one also has very large flaps whose purpose is more that of "getting out of the way" of the rotor wake in vertical flight than to provide additional lift. And two linked, fully articulated rotors with a rather complex blade twist. Trying to implement either would make this plane in a completely different type of aircraft, and push it to a completely different level of complexity (and cost!). I'd say that this one looks pretty good as it is, and is a much more sensible plane overall.
Jan 26, 2016, 05:19 PM
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Ran D. St. Clair's Avatar
Quote:
Originally Posted by Brandano
You are right, and I am not suggesting you to do that.
The full sized one also has very large flaps whose purpose is more that of "getting out of the way" of the rotor wake in vertical flight than to provide additional lift. And two linked, fully articulated rotors with a rather complex blade twist. Trying to implement either would make this plane in a completely different type of aircraft, and push it to a completely different level of complexity (and cost!). I'd say that this one looks pretty good as it is, and is a much more sensible plane overall.
I agree, simple and cheap is good. That being said, there is room to improve the illusion at relatively low additional cost and complexity. If the wings were to extend most of the way to the motor, and then the large flaps were to "get out of the way" then the loss of lift would be modest. A slightly more powerfull motor might make up the difference in lift without too much trouble, and the higher RPM of the more powerful motor would also increase the pitch speed helping make forward flight possible. Now add a profile motor pod made of depron and it looks a little bit more scale.

None of this is meant to say that what you have isn't great. I am just saying that there is room to make it even cooler without crossing over into the overly complex realm.


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