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Old Aug 04, 2011, 08:02 PM
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rcplanes1234's Avatar
United States, IA, West Des Moines
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Ok looking for new motors here is the ones Im looking at. Please suggest what one would work best with 9x6, 4cell, and 40amp esc.

http://www.bphobbies.com/view.asp?id...7&pid=B1858544
http://www.bphobbies.com/view.asp?id...7&pid=B1898547
http://www.bphobbies.com/view.asp?id...7&pid=B3915415
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Old Aug 04, 2011, 08:15 PM
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jsxx's Avatar
Wielka Brytania, Anglia, Derbyshire
Joined Jan 2011
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Originally Posted by rcplanes1234 View Post
Why would this effect the temp.
Wrong timmig i gues. .. my motor was extremly hot now cold . That was solution for my prblem. Does your 3 esc wires are same lenght?
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Old Aug 04, 2011, 08:20 PM
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Sydney, Australia
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Can anyone back this statement up? I've never heard of wire length effecting motor temp to the degree that it "solved a problem". Don't want to send the guy on a wild goose chase...
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Old Aug 04, 2011, 08:37 PM
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United States, CA, Sebastopol
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Can anyone back this statement up?
Can't. Speed of light, etc. No difference.
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Old Aug 04, 2011, 09:13 PM
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Originally Posted by subsonic View Post
Can anyone back this statement up? I've never heard of wire length effecting motor temp to the degree that it "solved a problem". Don't want to send the guy on a wild goose chase...
I couldn't imagine this making any difference at all, unless the system was so incredibly sensitive to resistance or inductance. That couldn't be because the motor resistance and inductance variations would more than swamp out any wire effect. But do check the soldering job on your connectors! Any resistance here due to a cold solder joint would be a major problem at any speed because the motor side of the ESC is always running at max peak current and voltage. The power is controlled by varying either the duty cycle or pulse rate. Don't know which for sure -never really scoped one.

The only critical lead length is on the battery side, and that is true only with ESC's that do not have proper bypassing on the battery leads at the ESC. In that case there is a possiblilty that lead inductance and high current pulses could cause voltage spikes that destroy the FETs. Bypass caps anywhere else won't do anything for that problem, they have to be on the ESC.

Cliff
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Old Aug 04, 2011, 10:47 PM
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United States, CO, Boulder
Joined Jul 2008
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Quote:
Originally Posted by rcplanes1234 View Post
Ok looking for new motors here is the ones Im looking at. Please suggest what one would work best with 9x6, 4cell, and 40amp esc.

http://www.bphobbies.com/view.asp?id...7&pid=B1858544
http://www.bphobbies.com/view.asp?id...7&pid=B1898547
http://www.bphobbies.com/view.asp?id...7&pid=B3915415
Well the last one weighs double what you are looking for. Cross that out. The first one is about right at 102g, but has a slightly higher Kv. The second one is an ounce heavier, with a lover Kv. Don't 4 cell users normally run a motor with a Kv of around 1000? I'm sure it won't make too much of a difference. I guess it depends how heavy your skywalker will be. Then suit the motor to the plane.
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Old Aug 04, 2011, 10:50 PM
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United States, OH, Parma
Joined Jul 2009
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2nd flight today; recorded with the GoPro. Almost got her trimmed.
Shes a great flyer so far, plenty of power but does carry speed on landing. I need to practice approaches for sure. Next video will be from the OSD view. This flight was FPV except for take off and landing.

Oh yea, and Im putting a piece of foam over the mic...



Skywalker FPV GoPro (4 min 44 sec)
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Old Aug 04, 2011, 11:35 PM
Joined Mar 2006
1,670 Posts
DO NOT CUT any
part of the wire length from any other motor, regardless of brand
or type. In most cases, only the last 1/4 inch or so of most motor wires
are able to be soldered . If they are clipped shorter, the motor will not run
properly, or may not run at all. You may also void the warranty of that motor.
If the motor is supplied with connectors you do not want to use, then make
sure to unsolder the original motor connectors from the wires - do not cut
them off.
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Old Aug 04, 2011, 11:37 PM
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rcplanes1234's Avatar
United States, IA, West Des Moines
Joined Jan 2010
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Ok will I figured out why the motor was getting so hot, it was one of those duh moments. Well I used hot glue for the motor mount just in case I need to take it off it would be much easier with it. So i ltook the motor apart and found that the back bearing had epoxy/hot glue and this was making the back bearing not move at all so there was lots of friction. So i took some rubbing alcohol and that did the trick and now the motor spins freely and actually feel right when you spin it. However I am still very steumped on the idea of prop vrs the pusher prop. You you look at prop with the numbers facing you, you see the skinny and the fat side of a blade. On a regular prop the prop will spin counter clockwise and the fat side will be the first to strike the air. Now what you are telling me is just make the motor spin the other way and you get a pusher prop, NO you dont!!! Now the aerodynamics of the blade have now changed and some thrust is lost because not the skiny edge of the blade is hitting the air first and a for correct air flow this is not right. It still works, but I believe you lose thrust doing so. Can some one please comment on this and explain if im right or wrong. Thanks!
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Old Aug 04, 2011, 11:39 PM
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United States, IA, West Des Moines
Joined Jan 2010
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Also last questions for the night. heheheh. I am still having some problems with tail of the plane. It seems to be rocked one way and will wiggly around in flight. When you take off you can see the bend and it makes me very nervous. What can I use to reinforce this? Thanks
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Old Aug 04, 2011, 11:49 PM
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Joined Nov 2008
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Quote:
Originally Posted by scrape View Post
DO NOT CUT any
part of the wire length from any other motor, regardless of brand
or type. In most cases, only the last 1/4 inch or so of most motor wires
are able to be soldered . If they are clipped shorter, the motor will not run
properly, or may not run at all. You may also void the warranty of that motor.
If the motor is supplied with connectors you do not want to use, then make
sure to unsolder the original motor connectors from the wires - do not cut
them off.
WTH ?
you can add extensions, you can cut off the bullets with impunity, shorten them to stubs, you can re-solder to your hearts desire.

The only thing to worry about is does the solder take, if it doesn't then scrape the cable to get rid of any coating first. Having a cold joint with non zero ohms can cause problems for an ESC.
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Old Aug 04, 2011, 11:53 PM
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Originally Posted by rcplanes1234 View Post
It still works, but I believe you lose thrust doing so. Can some one please comment on this and explain if im right or wrong. Thanks!
You are wrong. A "pusher prop" is for gas engines where you do not have the luxury of reversing direction. Just put on any electric prop so that the writing faces the "incoming" air flow in flight, and reverse the motor direction in the ESC, or cable swap, until it pushes.

The only argument for buying a pusher prop is the prop hub may be machined slightly better (flatter) on the important side. Not an issue for these planes.
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Old Aug 05, 2011, 02:16 AM
John
United States, WA, Mason
Joined Apr 2011
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After destroying my "Skywalker", I am testing my electronics to put back into a new plane. Most everything seems to be OK other than I can't get a picture out of my Vrx. I know the GoPro is putting out live feed. I assume since nothing really happened to the Vrx that it is probably OK. That leaves the OSD or the Vtx. Since the Vtx broke off the antenna and layed on the ground for an hour with battery still hooked up, does that pretty well mean that would ruin it for sure? Is there an easy way to test it? -- thanks, JOHN
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Old Aug 05, 2011, 03:17 AM
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Australia, NSW, Peakhurst
Joined Mar 2006
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Originally Posted by digitalCAM View Post
Since the Vtx broke off the antenna and layed on the ground for an hour with battery still hooked up, does that pretty well mean that would ruin it for sure? Is there an easy way to test it? -- thanks, JOHN
John,
Bummer about the SkyWalker. RIP
as for the VTX it is a 99% chance it too would also be dead. Not having a load on the VTX for that long would have cooked the finals .
unless you have someone that has a scope you can only try 3 things.
1) Apply power the the VTX and see if it gets as hot as it used to in about a minute.. if not then it is the VTX.
2) Use another VTX in its place that you know works.. doesn't matter what freq or power output or even if its not suited to FPV.
3) Make up a plug from the OSD to direct RCA to input to TV to check that the OSD is still working.

The chance of a VTX lasting 60 mins under power without an antenna attached are very slim indeed in fact even lasting that time without cooling air over the heat sink of the VTX is more than enough the blow the finals as well even if an antenna is attached.

Richard
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Old Aug 05, 2011, 04:23 AM
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rcmonster99's Avatar
United Kingdom, England, Milton Keynes
Joined Sep 2003
6,289 Posts
Quote:
Originally Posted by rcplanes1234 View Post
Ok will I figured out why the motor was getting so hot, it was one of those duh moments. Well I used hot glue for the motor mount just in case I need to take it off it would be much easier with it. So i ltook the motor apart and found that the back bearing had epoxy/hot glue and this was making the back bearing not move at all so there was lots of friction. So i took some rubbing alcohol and that did the trick and now the motor spins freely and actually feel right when you spin it.
Aha ! I was more or less sure it was similar to my problem...

Quote:
Originally Posted by rcplanes1234 View Post
However I am still very steumped on the idea of prop vrs the pusher prop. You you look at prop with the numbers facing you, you see the skinny and the fat side of a blade. On a regular prop the prop will spin counter clockwise and the fat side will be the first to strike the air. Now what you are telling me is just make the motor spin the other way and you get a pusher prop, NO you dont!!! Now the aerodynamics of the blade have now changed and some thrust is lost because not the skiny edge of the blade is hitting the air first and a for correct air flow this is not right. It still works, but I believe you lose thrust doing so. Can some one please comment on this and explain if im right or wrong. Thanks!
I think you might have misunderstood some of the comments...
whatever prop you get (standard or pusher) make sure the motor spins in a way that the thicker edge of the blade (the leading edge) hits the air first and the trailing edge (skinny edge ) last. Also make sure that whatever the plane, the curved side of the blade (the one with the letters) faces the nose of the plane . and there you have it.. recipe for success.

a propeller is nothing else than a wing the fact that it rotates is irrelevant. on a wing lift is achieved because the air being deflected by the top of the wing goes faster than the bottom of the wing and this creates a vacuum that pulls the wing upwards.
now, if you orient the wing vertically and you make it turn very fast, what we call lift it now called thrust

Quote:
Originally Posted by rcplanes1234 View Post
Also last questions for the night. heheheh. I am still having some problems with tail of the plane. It seems to be rocked one way and will wiggly around in flight. When you take off you can see the bend and it makes me very nervous. What can I use to reinforce this? Thanks
Some people have managed to add stiffness to the tail boom by adding fibre tape in a criss cross pattern along the boom.
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