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Best Kv Choice for Easy Glider E with stock Gearbox?

Old 09-17-2009, 12:36 PM
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cobrajocky
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Default Best Kv Choice for Easy Glider E with stock Gearbox?

Just getting into powered (E) gliders after some years with unpowered Slope Gliders and a couple years of E powered planes. I know my way around brushless motors and gearboxes, but not that combination in "E" gliders.

I picked the MPX Easy Glider E as my first foray into a medium sized 4ch plane. I bought the Kit version and I'm one to immediately do lots of mods and of course toss the anemic Brushed motor in favor of a much more efficient Brushless power train. I have an EZ* which I did the same and tossed the same Permax 400 and put in a Turnigy C2835-2700 (Kv) Inrunner mounted right into the stock motor pod, wires thru the fuse and the ESC inside the cockpit (air ducting cooling added).

I want to reuse the stock EzG E Gearbox, which I'v calculated is 3.5:1 ratio (35T main gear and 10T pinion). A Turnigy C2835 type Inrunner Brushless will bolt right up to it and I've already found a 3.2mm 10T Pinion of the right pitch for the Turnigy's.

My question is: What "effective" Kv (after Gearbox output) is best suited for a EzG E running the stock prop?

Also, in general for powered gliders (not "hotliners") of any type including balsa/plywood buildup, what is the consensus for preferred motor Kv to use? Lower Kv (under 1000) or higher Kv (1200 and above)?
Old 09-30-2009, 08:43 AM
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Default RE: Best Kv Choice for Easy Glider E with stock Gearbox?

Hi
can you please advise where you sourced your 10t pinion..having trouble getting one in the U.K
Old 09-30-2009, 03:54 PM
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Default RE: Best Kv Choice for Easy Glider E with stock Gearbox?

I got mine, a press fit and glue (Locktite gear glue - "Green") at a LHS, and it was a close out from a EF Helicopter line, $1.85USD. The last one.

You should probably Google "10T pinion 3.17 shaft" and you'll get a good hundred returns, perhaps even some in Euro.

Here are some US deadlers
http://www.aero-nuts.com/product_inf...roducts_id=321 Nice because it has a set screw, not glue needed

http://www.readyheli.com/RevCo_Hard_...p/ho-0500h.htm set screw and best looking, price is higher

http://www.twenga.co.uk/dir-Toys-Gam...g,Model-pinion (UK)

http://store.rcsupersales.net/servle...d-Steel/Detail

Let us know how your's works out.

Good luck





Old 10-01-2009, 09:07 AM
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Default RE: Best Kv Choice for Easy Glider E with stock Gearbox?

willdo Thanks and best regards
Old 10-01-2009, 11:00 AM
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Default RE: Best Kv Choice for Easy Glider E with stock Gearbox?

ORIGINAL: websterphreaky

Just getting into powered (E) gliders after some years with unpowered Slope Gliders and a couple years of E powered planes. I know my way around brushless motors and gearboxes, but not that combination in ''E'' gliders.

I picked the MPX Easy Glider E as my first foray into a medium sized 4ch plane. I bought the Kit version and I'm one to immediately do lots of mods and of course toss the anemic Brushed motor in favor of a much more efficient Brushless power train. I have an EZ* which I did the same and tossed the same Permax 400 and put in a Turnigy C2835-2700 (Kv) Inrunner mounted right into the stock motor pod, wires thru the fuse and the ESC inside the cockpit (air ducting cooling added).

I want to reuse the stock EzG E Gearbox, which I'v calculated is 3.5:1 ratio (35T main gear and 10T pinion). A Turnigy C2835 type Inrunner Brushless will bolt right up to it and I've already found a 3.2mm 10T Pinion of the right pitch for the Turnigy's.

My question is: What ''effective'' Kv (after Gearbox output) is best suited for a EzG E running the stock prop?

Also, in general for powered gliders (not ''hotliners'') of any type including balsa/plywood buildup, what is the consensus for preferred motor Kv to use? Lower Kv (under 1000) or higher Kv (1200 and above)?

I typically use outrunners in my gliders. I think I am using 1200 to 1400 kV outrunners in my 1.5 to 2M glidres spinning 8-12" props.

I will be putting up a 3M next season and will probably use something in the 600-800 kV range to run a bigger prop. It is the prop size and amp draw that drives my selection of the kV range of the motor. I target between 70 and 100 W/pound for my power to weight ratio. I am looking for climb, not speed. I don't need a rocket. I look to get to about 500-700 feet in about 20-40 seconds.

On a typical 2M glider I want about a 9-12" prop, roughly. On the 3M glider I will probably target an 12-16" prop. Not sure exactly yet.

Webocalc is a great tool to do some "what iffs" with or without a gearbox. Put in the numbers and play with the combinations till you get the combo you want in terms of prop size, amps, watts, thrust, etc. You can look at trade-offs between voltage and amps. Between kV and prop size.
http://flbeagle.rchomepage.com/softw..._imperial.html

A very useful tool.
Old 10-01-2009, 12:50 PM
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Default RE: Best Kv Choice for Easy Glider E with stock Gearbox?


ORIGINAL: aeajr

I typically use outrunners in my gliders. I think I am using 1200 to 1400 kV outrunners in my 1.5 to 2M glidres spinning 8-12'' props.

I will be putting up a 3M next season and will probably use something in the 600-800 kV range to run a bigger prop. It is the prop size and amp draw that drives my selection of the kV range of the motor. I target between 70 and 100 W/pound for my power to weight ratio. I am looking for climb, not speed. I don't need a rocket. I look to get to about 500-700 feet in about 20-40 seconds.

On a typical 2M glider I want about a 9-12'' prop, roughly. On the 3M glider I will probably target an 12-16'' prop. Not sure exactly yet.

Webocalc is a great tool to do some ''what iffs'' with or without a gearbox. Put in the numbers and play with the combinations till you get the combo you want in terms of prop size, amps, watts, thrust, etc. You can look at trade-offs between voltage and amps. Between kV and prop size.
http://flbeagle.rchomepage.com/softw..._imperial.html

A very useful tool.
Thanks for the very useful info and web tools for calculating the power plant. I use Drive Calculator for my non glider work-ups, but always open to new tools.

I like the idea of your "70 and 100 (Kv) W/pound for my power to weight ratio" formula; just some rough paper calc scribblings of my heavier planes seems to bear this out. I found out thanks to a reply email (finally) from Multiplex DE that the Easy Glider E's gearbox is a 3:1 (30T main and 10T pinion), so I've revised my Brushless Inrunner choice to the Turnigy 2835 - 2700Kv (same as I used in my EZ* w/o gearbox and 5x5 prop) which, through the stock gearbox delivers as reduced output of 900Kv and about 225 - 250watts depending on prop. I'll use the calc tools to choose the appropriate prop with the 2850 mAh 2S LiPO I will use.

I hope to make the EZ G E a great Soarer, but also a nice "warm+ liner" that will do some Glider style Acro.

Thanks again.
Old 10-05-2009, 04:31 PM
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Default RE: Best Kv Choice for Easy Glider E with stock Gearbox?

Hey aeajr,
"Watt" 3 meter bird are you planning on?
I hope to build an electric fuse for the Supra I want to build this winter. Bagging stuff arived, just have to finish building the wife's new front porch then I can get going on it!
Old 10-05-2009, 07:45 PM
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Default RE: Best Kv Choice for Easy Glider E with stock Gearbox?

I have a 3M Mantis that is set up for electric. The wing needs some fixing but other than that, it should be fine. Picked it up for a song. Definately not new.
Old 10-07-2009, 09:37 PM
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Default RE: Best Kv Choice for Easy Glider E with stock Gearbox?

aeajr,
Let us know what you end up with in the Mantis please. Several guys at our field have been using hobbyking.com motors with very good results.

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