Wanted: Your broken cross

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MontanaMac
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Wanted: Your broken cross

Post by MontanaMac » 14 Apr 2014, 03:03

Hello my name is Scott, and I own a small fabrication shop. I am working on new cross design which will be flexible yet flight stable. However I need spare parts and wiring harnesses, so I would like to buy your broken central cross. PM if you are interested.

BTW, Hello all! I'm new (obviously), but I plan to become active and contribute repair and mod videos and info. It's fun to become a part of this hobby!

Scott

Kyrt
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Re: Wanted: Your broken cross

Post by Kyrt » 14 Apr 2014, 11:07

Where do you live? I have one I expect, but I'm guessing you're in the states (Montana by any chance?). I'm in the UK.

MontanaMac
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Re: Wanted: Your broken cross

Post by MontanaMac » 14 Apr 2014, 16:04

That's the biggest problem with buying or selling a used central cross: Because of the size, the shipping costs more than the cross is really worth -- especially international shipping. I realize that majority of this forum's audience is in the UK, but I think there are also a fair number in the US too.

In general, if you have a broken cross, you can't expect to recover much money on it. But if yours is just going to get thrown away or sit forever and collect dust, I would sure be able to use it to help develop a new cross.

If and when I come out with a finished product for sale, I will offer a discount doubling your shipping costs (within reason). So if it cost you $12 to ship your broken cross to me, I would give you $24 off the new product.

What I am trying to develop is a cross which will be less expensive than the Sport Cross, and also less likely to break than the stock AR cross.

Jayson Hanes
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Re: Wanted: Your broken cross

Post by Jayson Hanes » 14 Apr 2014, 18:53

heh.. I just threw out 6 of them over the weekend..

MontanaMac
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Re: Wanted: Your broken cross

Post by MontanaMac » 14 Apr 2014, 22:59

You can reduce the shipping costs if you can disassemble the cross yourself. Then it can fit in an padded envelope.

Here's a video showing an easy way to to take the whole thing apart:
http://youtu.be/xZjG_Ok0SQo

Yes, as I mentioned in another thread, I am using these videos to teach myself Final Cut Pro, so some of the effects and editing are amateurish. Sorry...

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No longer need broken crosses

Post by MontanaMac » 15 May 2014, 21:35

Thanks to all who responded. I did receive two broken crosses (Thank you R.) which was enough for me to try a couple different ideas:
1) Replace the carbon fiber with aluminum.
2) Replace the rigid center cross with a flexible frame.

Both tests were successful, in that they achieved the goal of crash survivability. Both however, also had problems.

1) The aluminum arm model was lighter than stock. Most crashes under 20 feet resulted in a bent arm which was easily straightened. Flight stability seemed to be very good, and unaffected. A more serious crash would break or crease one or more arms, which then required replacement. This replacement cost less than $1, but took about 20 minutes time. The worst problem was the radio signal interference which seemed to be caused by the aluminum. This made flying beyond 50m (with no boosters) a bit iffy.

2) The flexible frame model was slightly heavier than stock, but the design allowed me to completely eliminate the hull, which was a net weight savings. In all crash tests, I never succeeded in breaking the frame or any carbon fiber arm. The problem was unstable flight. The prop arms would get to vibrating, and even resonating, which resulted in jerky flight and very poor camera stability.

I am now working on a different frame, but for the most part my experiments are over. I learned several valuable lessons:

a) Parrot really created an excellent design. Yes, the cross breaks, but it is stable in flight, is very light, isolates the main and nav boards well, and optimizes several competing variables.

b) The Sport Cross is also well designed, and it is quite impressive that the retail price is as low as it is.

c) The announcement of the BeBop removes most of the motivation for further improvement. I think Parrot is on the right track to create an even smaller UAV Quad, for the reasons of public opinion, safety, economy, and strength.

Thanks to all who responded. It has been very interesting to try out some different ideas. I hope to get a chance to test the BeBop, and will maybe work on some mods for it when it is released.

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