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Old Jun 28, 2010, 10:43 AM
I think my wheels fell off.
Thumb_number's Avatar
Perth
Joined Oct 2009
894 Posts
Quote:
Originally Posted by rcmonster99 View Post
This wing means you rely only on rudder elevator. may be the plane will be a dog to control.
Indeed, just as the glider the wing came from. Had a go at the oval tonight to see how things went. Not too bad, reduced the stall speed by about 1/3, and still had good control. The rudder is big enough for the dihedral of the 2m wing to give just as good control of the aircraft as the stock A/E setup. Sorry, no video as the light was to low for the GoPro.

Quote:
Originally Posted by IL76MD View Post
Hi guys,

here is my slow flying "truck" Sky Walker upgraded by 3m wings from old Bird 3000
Thats the stuff I had in mind when I dusted off my crunchy wing IL76MD. Exactly what I had in mind! Great stuff!

I'm on holidays at the end of the week so I will have tons of on-board GB for you guy's to filter through, both wings.
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Old Jun 28, 2010, 05:47 PM
I love FPV!
Cralis's Avatar
Eastern side of Australia
Joined Jan 2007
4,650 Posts
Did a test run of my motor in my garage.

Model: TR35-36-A
Input Voltage : 7.4V~11.1V (2~3S Li-po)
Kv : 1450rpm/V �} within 10%
Max. efficiency current : 15~25A
Current capacity : 35A/30s
Dimensions : 35mm X 36mm / 1.38in X 1.41in
Shaft diameter : 4mm / 0.16in
Weight : 106g / 3.74oz
Number of poles/magnets : 14
Recommended model weight : 1000~1900g / 35~67oz
Power equivalent : .25 to .30 IC glow engine
Suggested propeller: 9x6
Power: 400W+

Noticed at 1/4 stick, it's around 7 Amps... 1/2 stick is around 20 Amps.. and din't go further up and it was pushing the plane quite hard. Looks like if I went to 100%, I'd be amping pretty much above 40A....

I have a 40A ESC...

Cont Current: 40A
Burst Current: 55A

BEC Mode: Linear
BEC : 5v / 3A
Lipo Cells: 2-6
NiMH : 5-18
Weight: 33g
Size: 55x28x13mm

That's OK, right? That means I COULD run at close to 100% throttle (assuming close to 100% throttle = 40A) for the entire flight, now and again, go over for a few seconds? Up to 55A?

My other worry is that I'm mounting it in the compartment under the wings - and there's no airflow... so I fear she will overheat. Is this a valid concern? If so, any solutions?
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Old Jun 28, 2010, 06:15 PM
Post # 20 million
Kev.au's Avatar
Joined Aug 2009
2,646 Posts
Hey Cralis, i've opened up the front of that compartment to allow good air flow.
I have a bigger than needed ESC (60amp) to also help manage temps.







Cheers, Kev.
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Old Jun 28, 2010, 06:17 PM
I love FPV!
Cralis's Avatar
Eastern side of Australia
Joined Jan 2007
4,650 Posts
Nice Kev! Exactly what I wanted to see... I'll do that too... And you have an Out flow as well?
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Old Jun 28, 2010, 06:17 PM
Skint since 2000
ghost2212's Avatar
Reading, United Kingdom
Joined Oct 2008
1,503 Posts
Quote:
Originally Posted by Cralis View Post
Did a test run of my motor in my garage.
.......
In my opinion you need a bigger ESC as the ESC will always see full amps as if you were on full throttle so limiting the throttle will not stop the esc from overheating. As yo
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Old Jun 28, 2010, 06:20 PM
Post # 20 million
Kev.au's Avatar
Joined Aug 2009
2,646 Posts
Quote:
Originally Posted by Cralis View Post
Nice Kev! Exactly what I wanted to see... I'll do that too... And you have an Out flow as well?
Just the stock hole that the ESC wires come out of.




Cheers, kev.
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Old Jun 28, 2010, 06:57 PM
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MorrisM's Avatar
Oklahoma City
Joined May 2004
1,682 Posts
Quote:
Originally Posted by Cralis View Post
Did a test run of my motor in my garage.

Noticed at 1/4 stick, it's around 7 Amps... 1/2 stick is around 20 Amps.. and din't go further up and it was pushing the plane quite hard. Looks like if I went to 100%, I'd be amping pretty much above 40A....

I have a 40A ESC...

That's OK, right? That means I COULD run at close to 100% throttle (assuming close to 100% throttle = 40A) for the entire flight, now and again, go over for a few seconds? Up to 55A?
It seems to me you have too much prop on the motor. What prop and battery are you using? Since you have a 40A ESC, I would try to find a prop that ran no more than 35A at full throttle.
I do like the cooling hole idea. It only takes a little bit of air flow to make a big difference in cooling.
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Old Jun 28, 2010, 08:02 PM
I love FPV!
Cralis's Avatar
Eastern side of Australia
Joined Jan 2007
4,650 Posts
mm.. I'm running a APC 9x6 Thin Electric Propeller (LP 09060E). There was about 3 pages of discussion of this a while back, and this was the motor/prop that seemed to be best suited.

Also, the motor specs says:
Power equivalent : .25 to .30 IC glow engine
Suggested propeller: 9x6
Power: 400W+

Could this be an issue?
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Old Jun 28, 2010, 08:40 PM
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MorrisM's Avatar
Oklahoma City
Joined May 2004
1,682 Posts
If there was a discussion in this thread, I missed it. I do recall the motor discussion for your easy glider.
400 watts should be able to take your Skywalker near vertical. I would try a 9x4.7

Have you read the article about over amping the ESC at partial throttle? It's item 6 at the bottom of the page...
http://www.castlecreations.com/suppo...eral.html#gen6
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Last edited by MorrisM; Jun 28, 2010 at 09:13 PM.
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Old Jun 28, 2010, 10:23 PM
I love FPV!
Cralis's Avatar
Eastern side of Australia
Joined Jan 2007
4,650 Posts
Thanks for that.. Just read item 6, and that's pretty informative. It seems I might be doing the right thing though... My ESC is a 40A, with bursts of 55A. The motor seems to match it well then.. but as you say, maybe the prop is over kill with the pitch, and reducing it to 9x4.7 would allow for longer duration, and still give enough thrust to push the plane nicely?
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Old Jun 28, 2010, 11:08 PM
W4UAV
Gainesville, FL
Joined Nov 2005
1,043 Posts
I built my pan/tilt camera pod today and installed it. I have a 180 degree servo stretcher coming from Servocity. For now Im using the rudder channel for pan and the gear switch for forward/down tilt. I know there is a way to do throttle hold and have pan/tilt in flight, Ive seen the youtube video on it, I may try that and regain my rudder control back.. then again... I never was a fan of rudder control anyway.
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Old Jun 29, 2010, 03:13 AM
Houba ! Houba !!
rcmonster99's Avatar
United Kingdom, England, Milton Keynes
Joined Sep 2003
6,279 Posts
Quote:
Originally Posted by Cralis View Post

My other worry is that I'm mounting it in the compartment under the wings - and there's no airflow... so I fear she will overheat. Is this a valid concern? If so, any solutions?
I had the problem where the esc was in the compartment under the wing. bad Idea, it overheats and cuts out on you. you end up being in trouble with the plane not responding.

I am moving the esc outside the plane as per Sander's build, right under the motor and the ventilation hole.

Kev' solution is interesting but will be very inefficient.
To cool a piece of equipment effectively you need 3 times the exhaust size to the inlet size.
this creates a vacuum that will suck fresh air into the cavity.
I fear that Kev's exhaust is smaller that the inlet, therefore the fresh air will bounce off the cavity creating extra drag with very little cooling.
Imagine overfilling a test tube under the water tap.

On the subject of ESC...If the motor says 40A get at least a 50A esc, if you don't oversize the esc, it will work very hot at full throttle...
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Old Jun 29, 2010, 04:25 AM
jab
Unregistered User
Joined Aug 2007
1,091 Posts
Quote:
Originally Posted by Cralis View Post
Did a test run of...
The main reason you are getting high amps is that you have the 1450kv TR35-36. Around 1000kv would be better suited for a 9x6 so change to a 8x6 and you should get lower readings. Also don't panic if you get borderline amp reading on the ground. Static readings are higher then what you get in the air where there is less resistance for the prop. Also remember the burst rating for the ESC is 55A, so unless you plan on running full throttle for long periods of time...
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Old Jun 29, 2010, 06:26 AM
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MorrisM's Avatar
Oklahoma City
Joined May 2004
1,682 Posts
I did some quick calcs and here is some data for different props.
This is for a 1450kv motor on 3S lipo. APC E props

9x6 - 45A - 62oz static thrust
8x6 - 35A - 44oz
9x4.5 - 36A - 59oz

These numbers are theoretical, but should be close. YMMV
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Old Jun 29, 2010, 07:46 AM
I love FPV!
Cralis's Avatar
Eastern side of Australia
Joined Jan 2007
4,650 Posts
Thanks for that!
So, 9x4.5 would be the best suited for my 40A ESC, right?
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