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Old Feb 12, 2006, 02:28 PM
Electric flyer
31seb31's Avatar
Toulouse FRANCE
Joined Oct 2005
81 Posts
Hi,
i tryed a 9*4.7 slowflyer GWS propeller and it was a disaster!! I crashed my stang cause it didn't want to take speed and took down
It will be repared this week and i will try a 9*5 HD this time, like Mr LIN said.
Smokin' beaver, you said so-so for this propeller (HD??), what does it means ??
Sorry, i dont understand well english.
Weight of my stang is 510 grammes with a 3S1P 1800mAh LIPO (a little more now with glue).
Regards.
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Old Feb 19, 2006, 10:49 PM
Registerd Beaver
Smokin' Beaver's Avatar
Australia, WA, Warwick
Joined Jul 2003
3,580 Posts
Hi 31,
Really sorry to hear your misfortune.
Also apologies for slow response - just back from o/seas.
HD props are a particular type of prop the GWS folks make, it stands for Hyper Drive.
Here is a link to the page of GWS props
http://www.gws.com.tw/english/produc.../propeller.htm
There is a big performance difference between SF & HD & it can be very confusing.
Below is merely how I personally conceive my powerplant starting points depending on whether I want a fast plane (WWII warbirds) or a slow type one (WWI Biplanes or 3D). I found it so confusing too so I simplified the whole scenario & have always had more success than failure.
Your setup on a 9*4.7 is not always pushing the air fast enough away from the plane to make the wings 'lift' overcome the planes 'weight'. It has enough grunt to make it race along the ground, maybe even 'hop' flights but it is like driving off down a motorway in a car but only using first gear - very quickly you run out of useable power.
So what you need to get now is a prop which will give you something like 3rd or 4th gear.
Like a car, you can (if you are careful) drive off from standstill in 3rd gear.
But your model should spend 98% of it's time flying so the 1% @ take-off & 1% @ landing are not the main concern right now so 4th gear is the target.
If we look at the available pitch in all the GWS types of props, 3rd gear will be a 9050 HD. (there is no 9050SF)
4th gear will be 9060 SF. (there is no 9060 HD)
Now, I know from pure experience that a 9060SF on a 3:1 using the GWS 7.2V motor on 3S lipos is too much load for the motor - maybe 10~20 flights
So I would look at easing some load off the motor - so we should reduce the current draw down (but keeping 4th gear - the pitch of 6 inches)
Now we come out with an 8060. (Lucky for us GWS have a SF and an HD in this size!)
HD's from my tests always draw less current than the equivalent SF (many reasons for that but we won't study that now)
So the answer we come out with for a starting point is the 8060HD - your 3s lipo will spin it fast, it wont fry the motor in a hurry and you should get enough speed to fly.
I suppose a lot is experience with this D g'box for me.
It's just stuff you learn as you go.
It can all get as complicated as you like but at the end of the day, that's why you came here.
I hope my simplistic little ramble helps in some way.

Phil
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Old Feb 20, 2006, 12:13 AM
Registered User
Joined Feb 2006
256 Posts
Hey Phil, Do you have a system for brushless outrunner motors? I am having a hard time picking the right prop for my corsair. I have a Himaxx 2808-1160 1160KV with a 3cell 2100 lipo. I am not looking for a fast flight but I do want to have power. Most of my flights are in a football field. If you have info on how to Pick out the right prop that would be great. John
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Old Feb 20, 2006, 12:25 AM
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shschon's Avatar
United States, CA, SF
Joined Aug 2004
2,364 Posts
Quote:
Originally Posted by WATTSPD
Hey Phil, Do you have a system for brushless outrunner motors? I am having a hard time picking the right prop for my corsair. I have a Himaxx 2808-1160 1160KV with a 3cell 2100 lipo. I am not looking for a fast flight but I do want to have power. Most of my flights are in a football field. If you have info on how to Pick out the right prop that would be great. John

I flew this exact same motor using TP 1900 3 cell and a 8x4 prop with good results on a GWS Corsair. This gives you strong thrust and moderate speed.
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Old Feb 20, 2006, 01:42 PM
Registered User
Joined Feb 2006
256 Posts
Thanks Shschon. I'll give it a try. Was that an APC prop? Slo fly or regular?
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Old Feb 20, 2006, 01:53 PM
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Cincinnati, Ohio USA
Joined Nov 2000
4,359 Posts
I use Deans Micro connector on all of my battery packs. The Deans Micro is compact yet will handle 10 amps per pin. I wish more manufacturers would offer packs with the micro instead of that big darn Deans Ultra. I don't wqant to run a vacuum cleaner just a small brushless motor.

-Mike-
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Old Feb 20, 2006, 03:55 PM
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shschon's Avatar
United States, CA, SF
Joined Aug 2004
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Quote:
Originally Posted by WATTSPD
Thanks Shschon. I'll give it a try. Was that an APC prop? Slo fly or regular?


I don't know the brand of the prop. It is black and look similar to MAS (Master Air Screw) but I am not sure. The shape looks more like APC slow fly but it is more stiff like the APC electric.

I have also used APC 8x3.8 slow fly with good result (3 cell).
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Old Feb 21, 2006, 08:59 AM
Registerd Beaver
Smokin' Beaver's Avatar
Australia, WA, Warwick
Joined Jul 2003
3,580 Posts
John,
Same formula prop method for B/less as brushed but the B/L motor is more sensitive to changes.
The old can motors are very robust - B/L are generally more refined.
Always best to static test with an ammeter on the bench. Your motor shouldn't draw more than 12 amps on the bench at WOT (Wide Open Throttle).
I'd start your flight testing on a GWS 8040 HD. (should be ~ 10 to 11 amps @ 3s lipo)
Be careful of using gas engine props on electrics, many just don't work.

Phil
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Old Feb 21, 2006, 09:54 AM
Outcast outlaw
As far away from RCGroups and the AMA as possible!
Joined Aug 2004
6,601 Posts
Hey guys -- I'm flying a GWS Zero on a 3:1 (GWS "D") gearbox, a 400 speed GWS motor, a 9-cell NiMh battery, and a 9x7 SLOW FLYER prop.

The airplane flys just fine, and has 10+ minute flight times...

I'm considering what Mr. Lin (and the GWS staff) said -- I'm thinking of switching to a GWS 9x5 HD prop... However, I'm concerned that I will lose top speed AND thrust when making this move... Can anyone share their personal experience with this?

I also have an e-flite prop which came with my e-flite P-47 Thunderbolt... I think it's a 10x8 prop, and it looks like the GWS HD props... I'm considering trying the e-flite prop...
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Old Feb 22, 2006, 11:38 AM
Houng-wen Lin
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Shijr, Taiwan. DungGwan, China. City of Industry, California.
Joined Sep 2001
19,445 Posts
Think about to try GWS EP9075HD for speedy fly, yet low current flow?
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Old Feb 23, 2006, 05:37 AM
Registerd Beaver
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Australia, WA, Warwick
Joined Jul 2003
3,580 Posts
Red61,
I agree with Mr Lin.
Your combo is prob the best there is but the 9075HD would be worth a look.
I reckon a 9050 will be disapointing, good thrust for take off but would run out of legs when you need speed.
I ran the same on my GWS Spitfire and didn't like it as much - great for handlaunch but that was it's best attribute.
9075 will be similar performance to 9070 and drops straight onto the 4mm nuts on the shaft.
A touch less current draw so flights become longer by a minute or two.
Depends what you are after.
That's the fun of playing around with E-birds
Phil
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