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Old Nov 30, 2010, 05:01 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,222 Posts
Bob,

I noticed a nice servo tester at Neu motors the other day, only $10 and it is nicer than the one I have that cost the same:

http://www.neumotors.com/store/page9/page9.html

I use a external BEC to power up my servo tester and it will then handle a pair of servos. It is so quick and handy I couldn't live without it.

I got that one from Strong Motors but Don is out of stock on them now. Check out his instruction for doing motor tests, that is another good reason for having a servo tester.

Jack
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Old Nov 30, 2010, 06:51 PM
5,200 Led Lighted Bike-Bob P.
**neons**'s Avatar
USA, MA, Swansea
Joined Mar 2003
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Thanks Jack,
I got it on order. The user info is good also. This may be a safer way to run the motors than with the radio in hand. Good servos setups too.
**Neons** Bob
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Old Nov 30, 2010, 07:38 PM
Lori, hey, you're home early
CarreraGTSCS's Avatar
United States, NJ, Trenton
Joined Jan 2004
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Wow! This I'd one little powerhouse. I just soldered up the connectors and mounted the TP 3015-7 to the front of the Typhoon and used a new 11x7 3-blade prop. I used a 4s 2250 25c Zippy pack and a 50amp SS esc and an external ubec. Connected an Astro meter and let her rip. 37amps and 509watts. I'll have to check rpm's outside tomorrow. Maybe I'll pick up a fish scale one of these days so I can measure thrust. The Typhoon weighs 3.75 pounds and I plan to hand launch her. Might just have enough go. How do you calculate pitch speed?

Mike
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Old Nov 30, 2010, 08:29 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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Sounds impressive, Mike.

How was the heat after that run? Did it get very warm?

I like this calculator here, quick and simple:

http://www.rcpro.org/rccalc/PitchSpeed.aspx

Your actual flight speed will generally be 10% or so less I'm told.

If you loaded that 4S down to 14V or so (3.5V per cell) and got 80% of the no load RPM (14V x 1000 = 14,000) you might have had around 11,200 RPM. And that calculates out to 74 MPH. That might be in the ball park.

Jack
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Old Nov 30, 2010, 09:53 PM
Lori, hey, you're home early
CarreraGTSCS's Avatar
United States, NJ, Trenton
Joined Jan 2004
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Quote:
Originally Posted by jackerbes View Post
Sounds impressive, Mike.

How was the heat after that run? Did it get very warm?

I like this calculator here, quick and simple:

http://www.rcpro.org/rccalc/PitchSpeed.aspx

Your actual flight speed will generally be 10% or so less I'm told.

If you loaded that 4S down to 14V or so (3.5V per cell) and got 80% of the no load RPM (14V x 1000 = 14,000) you might have had around 11,200 RPM. And that calculates out to 74 MPH. That might be in the ball park.

Jack
Thanks Jack. I'll try to make time to run it again tomorrow and note the voltage under load. The can was no more than warm after three run ups of about 5-10 seconds each. While I had the watts slightly above the claimed max the amps were lower so I'm hoping that it balances out and won't cook the motor. It'll unload in the air as well so it might be ok.

Mike
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Old Dec 12, 2010, 07:17 PM
Ex AmA mEMBEr
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United States, CA, San Bernardino
Joined Feb 2010
846 Posts
not the stock wind we get?

this is the first time i've seen this motor anywhere but on a chinese website. i wonder if the factory is winding to this kv or if "airfield rc" is doing it. if the factory is why can't we get them wound with 21awg at 18 turns. this is on hobbypartz website i don't know if "airfield rc" is their stuff or not.

michael
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Old Dec 13, 2010, 05:32 PM
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manuel v's Avatar
Mexico, BC, Mexicali
Joined Aug 2004
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Quote:
Originally Posted by jackerbes View Post
Sounds impressive, Mike.

How was the heat after that run? Did it get very warm?

I like this calculator here, quick and simple:

http://www.rcpro.org/rccalc/PitchSpeed.aspx

Your actual flight speed will generally be 10% or so less I'm told.

If you loaded that 4S down to 14V or so (3.5V per cell) and got 80% of the no load RPM (14V x 1000 = 14,000) you might have had around 11,200 RPM. And that calculates out to 74 MPH. That might be in the ball park.

Jack


I have a EXcel with this function.
La convertidora.

Conversiones.

De Pulgadas a Centimetros.
De centimetros a Pulgadas
De gramos a Onzas
De Onzas a Gramos
Pies cuadrados a Decimetros cuadrados
Decimetros cuadrados a Pies Cuadrados
Pies cuadrados a pulgadas cuadradas
Pulgadas cuadradas a Pies cuadradas

De kilos a libras y onzas.

Calculo de KV Ratio

Duracion de bateria


Velocidad del modelo

Velocidad de perdida. Con datos en sistema Imperial y Metrico.

Area para DF,

para servos de oz a kilos.
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Old Dec 15, 2010, 04:27 PM
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northenden, manchester, england
Joined May 2009
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ok i have had this DT750 for a while, and i have been using it in a spaffnutz wing, i have been reading some of the comments and there seems to be quite a lot of different wind numbers, and was just wondering what you guys consider the best wind number and AWG to use, i dont plan on using anything bigger than a 10" prop, the plane i plan to use is a pusher with twin tails, which only allows a 10" prop due to the gap, its mainly for AP and possibly FPV so hope someone can give me the best combo for a 10" prop
carl
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Old Dec 15, 2010, 04:48 PM
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manuel v's Avatar
Mexico, BC, Mexicali
Joined Aug 2004
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maybe 12 turns. 20AWG.

KV 1143, GWS 10x6, 9862rpm, 300 watts , 71% effy. 1.4 kilos


Manuel V.
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Old Dec 15, 2010, 05:17 PM
WATTSUP.SE
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Sweden
Joined Dec 2001
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Quote:
Originally Posted by mchldpy View Post
this is the first time i've seen this motor anywhere but on a chinese website. i wonder if the factory is winding to this kv or if "airfield rc" is doing it. if the factory is why can't we get them wound with 21awg at 18 turns. this is on hobbypartz website i don't know if "airfield rc" is their stuff or not.

michael
Quite funny, today i got this motor (looks the same) from a friend, he had got it in an RTF Cessna kit, but tought it was realy bad, so he gave it to me. I removed the winding (badly made) and it was 18turns multistrand of 6x 0,25mm (i think 0,25 or simular) wires, terminated in Delta. The "soft" long shaft was bent after a crash, and i need some new bearings to.
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Old Dec 15, 2010, 06:15 PM
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northenden, manchester, england
Joined May 2009
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thanks manuel v but at the moment i dont have any 20AWG, but i do have some 21, 22, 24 AWG could you give me any numbers for any of these sizes please, i have just unwound it and it was 18turns multistrand of 6x 0,25mm (i think 0,25 or simular) as jocke states in his post, so now i have an empty motor waiting for fresh wire
thanks
carl
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Old Dec 15, 2010, 06:48 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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Quote:
Originally Posted by doggit View Post
ok i have had this DT750 for a while, and i have been using it in a spaffnutz wing, i have been reading some of the comments and there seems to be quite a lot of different wind numbers, and was just wondering what you guys consider the best wind number and AWG to use, i dont plan on using anything bigger than a 10" prop, the plane i plan to use is a pusher with twin tails, which only allows a 10" prop due to the gap, its mainly for AP and possibly FPV so hope someone can give me the best combo for a 10" prop
carl
Hi Carl,

I'm using this motor on my SpaFFFnutz too as you know. I thought I had done a 16 turn 21 AWG rewind on that but, as Manuel has pointed out, the 927 Kv that I got suggests that I probably actually did a 15 turn rewind. But I'm very happy with it.

I get the following in static testing on that motor with a Great Planes PowerFly Slow Fly 10 x 4.5 prop:

Amps: 22.75A
Watts: 231W
7,350 RPM

That is with a 4S A123 1100 mAh pack, the pack voltage started and 13.2V and pulled down to 10.1V under load. Performance with a 3S LiPO would be very similar.

When I fly with that motor it gets very little time at much more than half throttle. It is too fast and even a little scary for me at full throttle, I like to fly it most at half throttle or so.

There have been a couple of times when I flew in higher winds when I used most or even all of the power to get the plane back upwind against a heavy headwind. Those were times when I was glad to have that extra power in reserve of course.

I've flown the eLogger on the SpaFFFnutz a few times too and find I'm doing most of my flying at 5,000 to 6,000 RPM and with the motor pulling from 5A to 9A and generating 50 to 100 Watts or so.

So I'm not sure about best but the 16T21AWG DLRK wind with a Delta termination has been good for me.

Jack
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Old Dec 15, 2010, 10:13 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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Quote:
Originally Posted by Jocke View Post
Quite funny, today i got this motor (looks the same) from a friend, he had got it in an RTF Cessna kit, but tought it was realy bad, so he gave it to me. I removed the winding (badly made) and it was 18turns multistrand of 6x 0,25mm (i think 0,25 or simular) wires, terminated in Delta. The "soft" long shaft was bent after a crash, and i need some new bearings to.
The bearings are a little undersized for the motor I think. But they are what they are. Two bearings are needed, the size is 4 x 7 x 2.5mm (MR74ZZ).

It is not uncommon for people to complain that the bearings that these motor come with are noisy. I found lubricating them before the first use to be a good idea and also noticed that they don't seem to be particularly well made (a shield fell out while I was handling one). I lube them with 10W-40 Mobil 1 pure synthetic oil and use a vacuum chamber to get the oil inside the shields.

Shafts are easy enough to replace, you need a 4mm shaft that is about 50mm or longer. There are several shafts here that can be made to fit by cutting them to length and/or cutting an E-clip groove:

http://www.headsuprc.com/servlet/the...FTS/Categories

If you need help on cutting shafts to length or cutting grooves for E-clips this thread explains how to do it:

http://www.rcgroups.com/forums/showthread.php?t=1240725

Jack
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Old Dec 16, 2010, 12:43 AM
Ex AmA mEMBEr
mchldpy's Avatar
United States, CA, San Bernardino
Joined Feb 2010
846 Posts
Jocke wrote,
Quote:
"Quite funny, today i got this motor (looks the same) from a friend, he had got it in an RTF Cessna kit, but tought it was realy bad, so he gave it to me. I removed the winding (badly made) and it was 18turns multistrand of 6x 0,25mm (i think 0,25 or simular) wires, terminated in Delta. The "soft" long shaft was bent after a crash, and i need some new bearings to."
the bearings are MR74ZZ = 4 x 7 x 2.5 mm.
bphobbies<dot>com did have them on sale for (2) for $0.10, i bought 40 of them for $2.00. RC - Bearings<dot>com usually has them, not quite that cheap. the last 5 motors i bought from r2hobbies (turborix label) were pretty neatly wound, for this motor. the 2 i bought from hobbyking before that were a rats nest. that's just luck of the draw, no reflection on h/king. stock wind @ 750kv gives 40 oz. of thrust @ 19 amps with an apc 12 x 6e prop. the 1050kv that's in those
"airfield rc" planes isn't going to have the guts compared to the 750kv, i don't think. (but what do i know)
if you rewind with 18 turns of 21awg and run your motor on high timing you get 60 oz. of thrust @ around 24 amps with an apc 12 x 6e prop. for $10.00 that seems like a heck of a deal to me. let me know if you can't find any bearings and i'll mail you (2) of them. surely Sweden has a bearing or two somewhere.

michael
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Last edited by mchldpy; Dec 16, 2010 at 08:51 AM. Reason: don't know my sweden from my uk
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Old Dec 16, 2010, 12:52 AM
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manuel v's Avatar
Mexico, BC, Mexicali
Joined Aug 2004
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Carl

12,13 turns is for 20AWG.
14,15,16 is good for 21AWG. maybe 17turns.

to 3s lipo, 11Vots and GWS 10x6.

to 13 turns., 9473rpm,. 254 watts. 75% effy.
to 16 turns, 8188 rpm, 156 watts, 76.7% effy.

Manuel V.
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