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Old Jun 08, 2012, 03:49 AM
Fighting Gravity
bonnie9496's Avatar
Australia, WA, Perth
Joined Jan 2011
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Quote:
Originally Posted by kingsflyer View Post
You are going to have to use a lot more prop to get any speed out of that 870 kV motor. You might try a 10x10E APC and see if that helps.

The EF-1 Sundowner 36 is raced with a 1250 kV motor and an 8x8 prop on a 4-cell pack.

McD
Thanks.

No 10x10 available locally. Another 4 flights today,tried a APC 12x6 then and 11x8.5. These at static show around the same results. About 700w at 48 amps.
Better speed now, preferring the 11x8.5 This prop over amps the G25 motor however on inspection after flight the motor was barely warm.
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Old Jun 08, 2012, 06:13 AM
We shall serve the Lord
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United States, TX, Kingsland
Joined Sep 2005
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Quote:
Originally Posted by bonnie9496 View Post
preferring the 11x8.5 This prop over amps the G25 motor however on inspection after flight the motor was barely warm.
The numbers you get on the ground are static thrust numbers. Once airborne, the current draw is reduced as the prop unloads.
McD
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Old Jun 08, 2012, 11:57 PM
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flew the new combo today but the CC speedy was being uncoperative , forgot to take the progammer card and just coudn't get the throttle to calibrate fully with the Tx ,

took 5 seconds here at home with the CC field link ,

so will give it another go on monday weather permitting .

interesting take-off ,due to 13" prop there is not a great deal of ground clearance so basically held my foot on the tail wheel , ramp the power up and its airborne , no ground roll , I think its going to be quite fast from what I could get out of it today.

stay tuned
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Old Jun 09, 2012, 12:18 AM
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Antioch,CA,USA
Joined Dec 1999
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13" will fly it but is far from ideal.

Diameter gets you thrust while pitch gets you the speed. I've seen this plane go verticle on an 8" prop, why would you want any more thrust than that? The extra thrust is just wasted energy that could be used in another way.
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Old Jun 09, 2012, 03:10 AM
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Manu Simon's Avatar
Belgium
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Agreed a 13" prop is overkill unless you have a sundowner 50

Thrust is needed to overcome drag which increases exponentialy with speed, no only to go vertical....
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Old Jun 09, 2012, 11:32 PM
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Quote:
Originally Posted by Manu Simon View Post
Agreed a 13" prop is overkill unless you have a sundowner 50

Thrust is needed to overcome drag which increases exponentialy with speed, no only to go vertical....
Quote:
Originally Posted by GregG View Post
13" will fly it but is far from ideal.

Diameter gets you thrust while pitch gets you the speed. I've seen this plane go verticle on an 8" prop, why would you want any more thrust than that? The extra thrust is just wasted energy that could be used in another way.
I plan on trying a few different props on it when I get a chance to fly it , I have a Idea of what the 13x8 will be like from the same motor/prop/battery on 2 of my other planes ,

from e calc a 10x 10 seems to be the fastest prop speed , I will just see what the real world performance is like with the prop unloaded , airframe drag etc

I like the vertical speed a big prop provides , its very enjoyable flying as fast vertically as horizontally , hopefully I will find a nice compromise of both so my little sundowner can get flown more often as its been a bit of a "shelf queen" since the shoestring came along.

looks like it won't be till next weekend before it flys again , the rain is settling in
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Old Jun 10, 2012, 12:13 AM
Fighting Gravity
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Australia, WA, Perth
Joined Jan 2011
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3 more flights on the SD36. Improvement in speed with 700w setup but still not happy with the performance, so ordered a Power25 1250kv. I want to go fast!

Now just have to wait for the postman
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Old Jun 14, 2012, 05:41 PM
Fighting Gravity
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Australia, WA, Perth
Joined Jan 2011
550 Posts
The E-flite Power25 1250kv arrived today.

Fitted it up with a balanced 8x8 APC prop. Ran the meter on it using a new 4S 2800mAH 30C battery and it read 705watts @ 48amps. Thought the numbers would have been higher

Will see shortly if it is much faster in the air.


Later....

Well managed to put 4 batteries through the SD36 during the day and was disappointed with the speed. Used an 8x8 and a 9x6, top speed seemed about the same. Did notiice though that the plane came in to landing "hot" with no prop top slow it down. Second flight experimented with flaperons and was please with the speed they bleed off on approach.
Entered Posititive 20% flap and 5% elv on my DX8 flap setting. I believe flaperons should only be deployed when on a straight line to approach. I had a nasty tip stall about 30 feet high, when turning to final

Have changed out the prop to a 10x7 and at test shows 910Watts at 63 amps. Yet to try this setup

Should be a rocket ship now
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Last edited by bonnie9496; Jun 15, 2012 at 02:35 AM. Reason: Extra info
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Old Jun 17, 2012, 03:25 PM
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USA, KY, Ashland
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Is anyone using mini servos in the wing?
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Old Jun 17, 2012, 07:10 PM
Fighting Gravity
bonnie9496's Avatar
Australia, WA, Perth
Joined Jan 2011
550 Posts
"Have changed out the prop to a 10x7 and at test shows 910Watts at 63 amps. Yet to try this setup"

Reporting in on this setup. The speed is now better but still not to my satisfaction. Flew 5 flights with the Power 25 1250kv and 10x7 prop. Everything comes down cool.

Next step is a 10x10. A little concerned about the amps draw, will check it out once in hand.
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Old Jun 18, 2012, 05:59 AM
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Belgium
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I got good result with a 9x9 on my shoestring
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Old Jun 18, 2012, 09:27 AM
Fighting Gravity
bonnie9496's Avatar
Australia, WA, Perth
Joined Jan 2011
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Quote:
Originally Posted by Manu Simon View Post
I got good result with a 9x9 on my shoestring
Hmmmm.

Who sells a 9x9 for electric?
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Old Jun 19, 2012, 10:30 AM View Post
bsbauman
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Old Jun 19, 2012, 10:31 AM
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USA, KY, Ashland
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wth?
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Old Jun 19, 2012, 10:48 AM
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USA, GA, Atlanta
Joined Nov 2008
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Quote:
Originally Posted by bonnie9496 View Post
Hmmmm.

Who sells a 9x9 for electric?
Call on Atlanta Hobby @ 678.513.4450; it is not on his site but Cliff probably has a few in stock.

Quote:
Originally Posted by mike early View Post
wth?
Was this in reference to my post above? I just figured some of yall that like the SD36 might be interested in a larger version...
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