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Old Jan 05, 2009, 09:07 AM
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RiBell's Avatar
Canada, BC, Abbotsford
Joined Jan 2003
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Quote:
Originally Posted by Tim Farrar
Dag, excuse me for messing your thread up a little here but I just know you would like to see this video of a 19th Scale C-17 Globmaster !!
http://vids.myspace.com/index.cfm?fu...deoid=49746235

Seeya, Tim
First thing I noticed was the pilot's name.
I remember seeing a video of him flying a 12ish oz 3D machine in a gymnasium; a couple of years ago.
It was the first 3D video that I found interesting to watch. Not just a bunch of hovering; it was set to music, and the airplane had a pair of streamers from the wingtips.
Rick
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Old Jan 05, 2009, 10:16 AM
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coptercptn's Avatar
United States, AZ, Mesa
Joined Dec 2008
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I sent you a PM regarding Chargers the Newly released Bantam BC8DX will do you just fine...take a look...:

http://www.rcaccessory.com/index.asp...ROD&ProdID=386
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Old Jan 05, 2009, 10:27 AM
Sink? Circling now to confirm.
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United States, UT, American Fork
Joined May 2002
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Dumb suggestion by a dumb guy. I have been using carbon tubes for axles on an AP ship and I found that if I slide a smaller piece a carbon tube inside the main tube and then wrap it with strapping tape that even when it breaks it is still very usable. Now I know that once the shaft breaks on your motors you will not want to continue flying but something like the tube in a tube and wrapped may keep it from detonating and ripping other things to shreds once it goes.


OK back to smart people talk.
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Old Jan 05, 2009, 11:05 AM
HAL... Open the damn doors!
jfetter's Avatar
Miramar, Florida
Joined Jul 2007
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Quote:
Originally Posted by coptercptn
I sent you a PM regarding Chargers the Newly released Bantam BC8DX will do you just fine...take a look...:

http://www.rcaccessory.com/index.asp...ROD&ProdID=386
You get more bang for the buck with the Hyperion. The Bantam is limited to 160 watts/port while the Hyperion DUO does 180 watts/port...

Jack
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Old Jan 05, 2009, 11:21 AM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
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Quote:
Originally Posted by JONBOYLEMON
Dumb segestion by a dumb guy. I have been using carbon tubes for axles on an AP ship and I found that if I slide a smaller piece a carbon tube inside the main tube and then wrap it with strapping tape that even when it breaks it is still very usable. Now I know that once the shaft breaks on your motors you will not want to continue flying but something like the tube in a tube and wrapped may keep it from detonating and ripping other things to shreds once it goes.


OK back to smart people talk.
Thanks,
Does the inner tube fit perfect, I am looking at RPM's about 4200. If it does not fit perfect it may cause a balance problem.

Also a dumb question, what is a AP ship?

Thanks, DAG
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Old Jan 05, 2009, 11:29 AM
Sink? Circling now to confirm.
JONBOYLEMON's Avatar
United States, UT, American Fork
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Yes its a tight squeeze. I dont have the sizes but it is very tight. Not so tight that you can't slide it in but its soo close that its like it was meant to be.

I know I have had several pieces of carbon tube & rod that were seemingly made to be sleeved.



While my axles never do 4200 RPM, unless I am taxing at 476 mph, I think the idea is worthy. It adds a ton of strength as when the tube tries to break there is resistance to caving in as well as blowing out. I broke the axle 6 month ago but I have been too lazy to change out as it still is working just fine.



AP = Aerial Photography
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Old Jan 05, 2009, 12:14 PM
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Troms, Norway
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The problem with regulat carbon tubes and rods is that they have unidirectional fibers. This makes them unsuitable for transmitting high torque. A tube with unidirectional diagonal fibres with layers in alternating directions would be perfect and would not fail. Even a woven tube would be better I think. I attached a picture of a woven tube I have. Still, 10 mm, thick walled unidirectional tubing might be enough for the job though, but with such a high power level and low rpm as 4200 rpm the torque will be immense.
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Old Jan 05, 2009, 12:23 PM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
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Quote:
Originally Posted by Lynxman
The problem with regulat carbon tubes and rods is that they have unidirectional fibers. This makes them unsuitable for transmitting high torque. A tube with unidirectional diagonal fibres with layers in alternating directions would be perfect and would not fail. Even a woven tube would be better I think. I attached a picture of a woven tube I have.

With such a high power level and low rpm as 4200 the torque will be immense.
Thanks Lynxman,
Here is some info.
So far I am seeing with a 20/14 3blade setup about 45-47 amps on ecalc. That is at about 4400rpm. Very late last night I took a 12" CF tube and epoxied a grade 8 bolt in each end, then with it in the vise I put my torque wrench and turned it off the scale (I am guessing about 280 pounds) and the tube did not even deform.

Tonight I am setting up a test nacelle and by Friday hope to do some full power test. Keep in mind my low RPM is not limited by the power of the motor but by my design and target performance and speed that I want.

Comments welcome.

Thanks,

DAG
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Old Jan 05, 2009, 12:26 PM
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Lynxman's Avatar
Troms, Norway
Joined Jan 2004
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Cool! Sounds like it's some very strong tubing. I'll look forward to your test results.
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Old Jan 05, 2009, 12:48 PM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
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Quote:
Originally Posted by Lynxman
Cool! Sounds like it's some very strong tubing. I'll look forward to your test results.
I hope it works, if not I will find some tubes with unidirectional diagonal fibers.

Thanks, and be safe.

DAG
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Old Jan 05, 2009, 01:49 PM
No such thing as overpowered
Wilit run? 353's Avatar
Suffolk, England
Joined Sep 2008
1,793 Posts
what liPos whill you use and how many
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Old Jan 05, 2009, 01:56 PM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
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Quote:
Originally Posted by Wilit run? 353
what liPos whill you use and how many
I have been looking at Thunderpower, Zippy, and lately airpower. There will be 2 each 4C@5000mah wired is series to each Hacker motor, so each motor will see 8 cells. Soooo this plane will have 6 sets of 2 pair 4 cell 5000mah batteries. Thats 12 4 cell packs $$$$$$$ .

Thanks, DAG
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Old Jan 05, 2009, 02:08 PM
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United States, AZ, Quartzsite
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Not to mention the six chargers
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Old Jan 05, 2009, 02:17 PM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
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Quote:
Originally Posted by Carl Petersen
Not to mention the six chargers
Nope
3 dual chargers. $$$$$$

Like I said I am not made of money, but boy this is adding up. But it is cheaper than a girl friend .

Thanks.
DAG
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Old Jan 05, 2009, 03:56 PM
HAL... Open the damn doors!
jfetter's Avatar
Miramar, Florida
Joined Jul 2007
8,158 Posts
Quote:
Originally Posted by dag214
Nope
3 dual chargers. $$$$$$

Like I said I am not made of money, but boy this is adding up. But it is cheaper than a girl friend .

Thanks.
DAG
Dag,

I don't want to start the power debate again but I'm having a hard time finding the Hacker motors you ended up going with, I can only find the post about them helping you size the motors and picking the right one. Can you please post the exact motor, ESC, battery and prop one more time?

Thanks,

Jack
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