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Old Oct 12, 2014, 02:56 PM
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Joined Jun 2005
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IfIHadWings Tim, Thanks for showing the Can-Doo. It obviously is a good design and is a step in the right direction for a refreshing change. Your model looks like a winner. Please let us know how the maiden goes.

Charles
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Old Oct 12, 2014, 04:14 PM
What could possibly go wrong?
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Market Harborough
Joined Apr 2006
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For all you Burt Rutan fans, have a look at this:
http://www.chonday.com/Videos/jegalctospc2
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Old Oct 13, 2014, 12:01 PM
robinson727
USA, MS, Byhalia
Joined Nov 2010
127 Posts
Variant canard

All..
Attached ia a photo of an old "Boston"indoor freeflight design I scaled up 200%.
It uses a 50W 800kv Mpi motor and 800mah 2cell. We use the canards for roll/pitch .. Still tweaking.. but we are getting there and having a lot of fun in the process.
Al
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Old Oct 13, 2014, 01:37 PM
who has rabbit ears down
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United States, MN, Buffalo
Joined Jan 2007
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That does look like a hoot! 'specially the landing gear!
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Old Oct 13, 2014, 08:38 PM
robinson727
USA, MS, Byhalia
Joined Nov 2010
127 Posts
Variant

The deal was to make Variant look like an oldie FF model.. I had built one in the 80's and always wanted to scale it up.. but keep "the look" so we did.
I laminated the wheels outa 1/4" balsa scrap, glued 1/4" dowel in the center then turned the blanks on the lathe & covered with Microlite, a groove in the center holds the O ring tires on. The only major change so far is holding the canard on with a magnet so it can pop off easily.
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Old Oct 14, 2014, 03:04 AM
Sokol
JureZ's Avatar
United States, CA, Walnut Creek
Joined Jul 2013
202 Posts
Quote:
Originally Posted by robinson727 View Post
All..
Attached ia a photo of an old "Boston"indoor freeflight design I scaled up 200%.
It uses a 50W 800kv Mpi motor and 800mah 2cell. We use the canards for roll/pitch .. Still tweaking.. but we are getting there and having a lot of fun in the process.
Al
could you provide details about the motor shaft extension ?
I am very curious about it. Or am I mistaken... ?
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Old Oct 14, 2014, 08:41 AM
robinson727
USA, MS, Byhalia
Joined Nov 2010
127 Posts
Variant shaft drive

Sure.. but it's going to be a little long.. sorry..
We used .032 piano wire for the drive shaft and for this one , no shaft log (outer housing) just 2 disks cut outa 1/16" ply on the 2 bulkheads between the motor and the prop. The coupling is just a scrap piece of 6061T-6 turned on the lathe and cut to .400" length. One end is bored 2 mm for the Mpi motor and the other side is bored .032" for the wire.. I cross drilled and tapped it 4-40 to accommodate the 4 set (grub)screws .. The prop side is a piece of 3/32" brass rod drilled .032 for the piano wire which is silver soldered to the stub shaft and then threaded 3-48 for the WesTechmik 250 mm carbon fiber prop .. (which is also drilled and tapped 3-48)

A short piece of 1/4" brass tube carries the prop side roller bearing (Boca Bearings, cheap) and since I only had the one bearing, I turned a piece of UHMW
plastic for an inner bushing.. A drop of thick CA to secure the bearing and bushing works great and makes for a troublefree installation..
Questions?? Fire away.. I'll help any way I can..
Al
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Old Oct 14, 2014, 09:26 AM
Sokol
JureZ's Avatar
United States, CA, Walnut Creek
Joined Jul 2013
202 Posts
Thanks Al,

very fine, nice job!
I noticed but could not tell much from your earlier pictures.

I was thinking about motor shaft extensions, and saw some accessories for boat application.

In my case , I do not have a lathe , so my creative juices get limited by the implementation resources. I have a small collection of scavenged bearings from Hard Disk Drives, which would be good for this use. Will see...

Proper alignment is key to vibration free operation, is it true ? Do you get any resonances ? I think that they should be mitigated by the two short spans between the motor and the prop.

thanks, Jure Z.
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Old Oct 14, 2014, 09:30 AM
What could possibly go wrong?
nickchud's Avatar
Market Harborough
Joined Apr 2006
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wow! That's a real piece of craftsmanship Al and, to judge from the photos, so is the plane.

I was wondering how it might be done without a lathe. For such a lightweight plane and a big slow prop, perhaps it would be possible to get away with a rubber band like the old days. At the motor end it could be attached to a prop-saver type of collet. That would also mean that u/c was not really necessary.

Do you think that would work.

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Old Oct 15, 2014, 01:47 PM
robinson727
USA, MS, Byhalia
Joined Nov 2010
127 Posts
extension shaft

Hi Nick and JureZ..
Thank you for the complements.. weird stuff is fun and canards fit the bill.. :-)

Alignment with the pianio wire drive is not real critical and so far.. no resonance issues.. Also.. We had also thought about winding a rubber band intermittantly thru a sprag clutch and spinning a carved balsa prop but the tension and startup torque would be pretty high so I stayed simple with direct drive and the light weight carbon prop..
This is the third drive set up and I think we got it down pretty good and FYI.. boat stuff is to heavy.. keep it light.. Attached is a pic of "Gray Ghost" .. Because of the
high RPM it required a different system, here's a coupla snaps for ideas and a short video of it flying.
Al
Gray Ghost Mini pylon racer (1 min 30 sec)
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Last edited by robinson727; Oct 15, 2014 at 01:56 PM. Reason: additional snaps
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Old Oct 15, 2014, 02:54 PM
who has rabbit ears down
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United States, MN, Buffalo
Joined Jan 2007
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I Love that last pic there Al! How dod ya get the L gear Upside down? on 37 of my aircraft, only 3 had been with those wheelrotatorspinnythingamajigs!
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