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Old May 01, 2003, 09:50 AM
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wolfance's Avatar
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gws gear size a, b, c, d, whats diff?

Hello,

I noticed that the engines has different gear sizes, letters on one (a) and (d) on the second motor I have.

A seems smaller (the drive gear?) than D, so would this mean A goes faster?

THanks
lance
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Old May 01, 2003, 10:15 AM
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E-Challenged's Avatar
United States, CA, Garden Grove
Joined Oct 2000
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Go to the GWS website and see the gear ratio tables for the different motor/gearbox combinations. The ratios get larger from A to D and you go from smaller to larger diameter props using the same motor. For example, a GWS 300C system with an A gear ratio uses an 8X5 prop and a D gear ratio might use a 10X5. An 8X5 prop gives higher prop speed with less thrust and pulls lower current and a 10X5 prop gives more thrust at less prop speed but pulls higher current. I use the A drive with 8X5 prop for small scale models with short landing gears and the B drive with 9X7 prop for my Switchback.
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Old May 01, 2003, 10:18 AM
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Mark Sanders's Avatar
Windsor, UK
Joined Jun 2001
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5.86:1, 7:1, 8.6:1, & 9.66:1 !!

Gear ratios !
they do others too from 3.5:1 to 11.77:1

http://www.aircraft-world.com/prod_d...system/ips.htm
for more info.

Great for the money !!!
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Old May 01, 2003, 10:21 AM
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wolfance's Avatar
colorado
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what if...

I use the same prop?

Suppose prop 11x8, on a geared A and then a geared D gear- what will the difference be?

I'll go check the web site and hopefully your answers will help me make sense of the charts over there

lance
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Old May 01, 2003, 10:31 AM
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wolfance's Avatar
colorado
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if...

Quote:
Originally posted by Mark Sanders
5.86:1, 7:1, 8.6:1, & 9.66:1 !!

Gear ratios !
they do others too from 3.5:1 to 11.77:1

http://www.aircraft-world.com/prod_d...system/ips.htm
for more info.

Great for the money !!!
I look at that site, it says for a geared A drive gear, to use a 9070 prop to get a good rating. I dont think a drive a gear and a 9070 (does this mean 9x7) prop will work good on a slowstick?

The motor and drive gear is D, that means I should get a 12x8 prop? (if I use 11x8 will it fly slower than the 12x8?)

With A gear, if I put a 1180 on it, as opposed to 9070 will it still fly as a slowflyer?

(If i put a 9x7) on, will it have better performance?

(I know NOTHING about this, thus asking to learn)

lance
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Old May 01, 2003, 11:24 AM
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boomerace's Avatar
Eugene, Oregon, United States
Joined Sep 2001
19,187 Posts
Re: if...

Quote:
Originally posted by wolfance
I look at that site, it says for a geared A drive gear, to use a 9070 prop to get a good rating. I dont think a drive a gear and a 9070 (does this mean 9x7) prop will work good on a slowstick?

The motor and drive gear is D, that means I should get a 12x8 prop? (if I use 11x8 will it fly slower than the 12x8?)

With A gear, if I put a 1180 on it, as opposed to 9070 will it still fly as a slowflyer?

(If i put a 9x7) on, will it have better performance?

(I know NOTHING about this, thus asking to learn)

lance
Lance,
You are asking for easy answers to a involved subject! Each plane has a motor, gearbox, prop and battery combo that will provide the best performance for the particular airframe! If you look at the figures from GWS they give Static thrust and watts figures for the various combos! As a general rule Watts per pound of weight is a good measure of performance! I generally use 50 to 60 watts per pound as a guide to my sedate slow flyers, 60 to 75 watts per pound will allow loops from level flight and better performance, 75 to 100 watts per pound will be what I would use for my Warbirds, 100 to 150 will give unlimited vertical and anything over that you will not need wings!
The thing is that other things have to be considered! If you had a slick airframe and a prop/ motor combo gave you the required watts but it was with a say 12 X 5.5 prop the prop would quit pulling the plane along because the pitch speed of the prop wasn't enough to get the plane up to the speed needed for best performance so you would end up with a fast plane that would probably get off the ground in a hurry but then would hardly fly becase the prop wouldn't keep up with the planes need to fly faster to make use of the slick wing design! The best tool is Motocalc which allows you to try various combos. It is not perfect but will give you a place to start your fine tuning! With a kit plane the designer will get you started in the right ball park with his recommended power systems but as you can see by this forum there is still room for improvement over the supplied power systems! Hope this helps some and didn't confuse you further!
boomer
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Old May 01, 2003, 11:40 AM
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wolfance's Avatar
colorado
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and...

GW/SLOW STICK-EPS300C
Power System
EPS300C
Propeller
EP1180


It only says to use an ep1180 prop with its eps300c this (with my 9.6v batteries) gives me 67.20 power(w) which I would be happy with.
However a 9070 prop with 9.6volt will give me 84(w) power! (yeah, watch me rip the wings off this plane, ha ha )

So, why wouldn't this smaller prop be ideal for the slowstick? (other than too much power) It has less thrust.

Can you be so kind as to define: THrust, and pitch.

Thanks!
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Old May 01, 2003, 12:02 PM
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boomerace's Avatar
Eugene, Oregon, United States
Joined Sep 2001
19,187 Posts
Re: and...

Quote:
Originally posted by wolfance
GW/SLOW STICK-EPS300C
Power System
EPS300C
Propeller
EP1180


It only says to use an ep1180 prop with its eps300c this (with my 9.6v batteries) gives me 67.20 power(w) which I would be happy with.
However a 9070 prop with 9.6volt will give me 84(w) power! (yeah, watch me rip the wings off this plane, ha ha )

So, why wouldn't this smaller prop be ideal for the slowstick? (other than too much power) It has less thrust.

Can you be so kind as to define: THrust, and pitch.

Thanks!
You are confusing power systems! The 300C series has many different gear combos available . On a slow airframe like the SS you need a big low pitched prop! The 9 X 7 you are quoting is on the 300C-B! The SS comes with a 300C-D which will not work with a 9 X 7 prop as you probably would hardly get off the ground as the Gearbox can't spin it fast enough for it to be effective! This gets back to my original lead in statement! There is a "best" motor /Gearbox/ battery combo for each airframe! The gearing of the 300C-B with the 9 X 7 prop would be a very poor combo for the SS as it would be turning to prop too fast for the airframe!
boomer
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Old May 01, 2003, 12:17 PM
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colorado
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ah

Gotcha! didnt see the difference till now. Boy, I feel like a dunce. But at least I am learning by bounds and leaps.

for the eps300, geared d, it appears what I have is the best (1180)

now that i know the difference, I found out that the motor with the a gearing is really a eps 100 (took it off my dandy plane and www.mountainmodels shows it as an gws eps 100a)
This means, i had to look at a different chart and it shows that with a 1080-1180 prop, it only draws 28-31 watts.
(this is a surprise, i thought the dandy motor/gear was more powerful than the slowstick's stock?)

If I was right, with above thoughts, i just saved myself a huge headache.
If i was wrong, then correct me!!
(thy shall not spare the rod)

Lance
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Old May 01, 2003, 12:31 PM
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boomerace's Avatar
Eugene, Oregon, United States
Joined Sep 2001
19,187 Posts
Re: ah

Quote:
Originally posted by wolfance
Gotcha! didnt see the difference till now. Boy, I feel like a dunce. But at least I am learning by bounds and leaps.

for the eps300, geared d, it appears what I have is the best (1180)

now that i know the difference, I found out that the motor with the a gearing is really a eps 100 (took it off my dandy plane and www.mountainmodels shows it as an gws eps 100a)
This means, i had to look at a different chart and it shows that with a 1080-1180 prop, it only draws 28-31 watts.
(this is a surprise, i thought the dandy motor/gear was more powerful than the slowstick's stock?)

If I was right, with above thoughts, i just saved myself a huge headache.
If i was wrong, then correct me!!
(thy shall not spare the rod)

Lance
You are right the 100 is a less powerful motor than the 300! On my Dandy sport I am using the same motor/GB combo as the SS with a 12 X 6 prop I am getting almost vertical performance!
boomer
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