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Old Jun 30, 2015, 03:41 PM
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Build Log
5-foot Dornier DO-X

This isn't exactly a build log - I won't be going into every step of construction but will post pictures as I go along and invite comments and suggestions.

For some time I have contemplated this build but have hesitated because of the cost of 12 motors and ESCs. But I found some very inexpensive brushed motors that I plan to run in parallel: 4 sets of three.

I am basing the build on the 1978 plans by Don Srull, enlarged to a five foot wingspan. I have redesigned the engine pods to be a bit more scale and to accommodate two motors in each one.

I have been working on the fuselage for a couple of weeks and the pictures will show progress to date,
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Last edited by gsloca; Oct 03, 2015 at 06:07 PM.
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Old Jun 30, 2015, 04:15 PM
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DO-X propellers

For this build I need propellers. I need 4-blade tractor and pusher props, 4.5 to 4,75 inches diameter. Any ideas?
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Old Jun 30, 2015, 04:38 PM
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71% of the world is runway . .
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Nice project !!

maybe you can use two 2 blade props on one motor to make a 4 blade ?

Cheers,

Bart
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Old Jun 30, 2015, 05:02 PM
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Cut away half the hub of a GWS prop . Front half of one, rear half of the other. Half lap them together using M.E.K. to make a solvent weld.
Also, be careful with series/parallel of brushed motors. They will make a lot of radio noise. Not sure if it will affect 2.4gHz, but it is hell on 72mHz! Use a schottky diode and capacitor across each motor to suppress brush arcing and EMI.
I tried that connection on my Hughes Hercules and ended up taking the low voltage series/parallel connected motors out and going with all 8 in parallel.
Glenn
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Old Jun 30, 2015, 08:46 PM
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In Mid 90's the fellow who is/was? Jeti.... built a 3 meter Scale DoX from hotwired Polystyrene foam.
It flew well on Throttle Aileron and Elevator......Look it up if curious ?
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Old Jul 01, 2015, 12:11 AM
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Looks like a very promising start!
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Old Jul 09, 2015, 10:21 PM
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Here are a few more pictures. Things are moving along smoothly. One gimmick I've added is a servo with a driver to oscillate the direction finder loop antenna in front of the cabin. The plane will also have working navigation and landing lights. The first three pictures are the water rudder stuffing box and linkage. The last picture shows the inside of the hatch with the motor arming plug and switches to turn on the DF oscillator and the lights.
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Old Jul 10, 2015, 08:41 AM
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Oh no, not again!
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I love it! A man after mine own heart. Like 12 motors isn't enough complication, let's go with a moving DF loop and lights.

Getting a vicarious fix.

Regards,
Jeff
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Old Jul 10, 2015, 09:46 AM
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You can see some photos of Don's DO-X here.

https://www.flickr.com/photos/124772115@N02/sets/

I have been watching Don fly his beautiful DO-X for 35 years now. I will send this build to him--he will get a Kick out of it.
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Old Aug 10, 2015, 07:16 PM
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Thanks for the link to Don's DO-X pictures. I had seen a few but these are great! I'm afraid my DO-X is stalled out for a time; I had back surgery two weeks ago tomorrow and have most of my activities severely restricted.
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Old Sep 26, 2015, 11:58 PM
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Progress is slow but steady. Here are the latest pictures. First two are of the balsa wing ribs as cut by my son's CNC router. Next is the start of the wing center section, The next three are the front of the fuselage with the nose block attached and sanded to shape. The hole in the right side of the hull will be the anchor pocket (yes, Virginia, there is an anchor). Finally a closeup of the wing center section with the leading edge attached and roughed to shape, the shear-web spar installed, and completed trailing edge .
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Old Sep 27, 2015, 12:32 AM
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Nice work. The wing section is beautiful.
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Old Sep 27, 2015, 01:43 PM
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Very nice work so far !

Cheers,

Bart
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Old Sep 29, 2015, 07:09 PM
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You going have great looking Do-X. The propellers might be challenge. To get enough thrust, you might have to make four blade props your self. I am enclosing pictures showing how I made my 12 three blade prop. I am not encouraging you to follow me. If done incorrectly you might get hurt.


Quote:
Originally Posted by gsloca View Post
For this build I need propellers. I need 4-blade tractor and pusher props, 4.5 to 4,75 inches diameter. Any ideas?
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