I'm building a altezza motorized sailplane and am trying to source a motor that will fit in the narrow nose. looks to be about 24mm wide inner measurement! if anyone has a recommendation i might try it would be great. searching now. thanks. crazy small! I found a great plains ammo 24 -33 -3180 in runner brushless wondering if that would be a viable option for this sailplane. Expected weight complete around 50 ounces. 100” ws. Thank you

i don't think that Ammo is a viable choice unless it has a gearbox fitted. On 3S, a 6x3 prop puts it way over the current limits. On 2S, a 6x4 is right on the 20A short term rating, but then you're only pulling 135W for a 3lb+ sailplane.

The Powerline geared drives here https://www.hyperflight.co.uk/produc...&subcat=Geared are ideal at 22mm, but you pay for the privilege.

The Reisenauer Micro Edition gearbox on a Tenshock Viper is also a 22mm solution and a lot less expensive https://www.reisenauer.de/artikelauswahl.php?kid=166

Quad motors are generally specified as a 4 digit number, where the first 2 digits are the diameter and the second 2 digits are the rotor thickness. So a 2008 motor would be 20mm in diameter and have an 8mm tall rotor. Usually, these motors can be had in a few different KVs. And many will have prop/battery/power tables to help you choose. Ignore the model airplane websites and check out some drone/quad sites like GetFPV or RaceDayQuads. In fact, I think RDQ's website lets you select motors from their inventory based on physical dimensions...

Quad motor dimensions refer to the stator size. The overall exterior measurements will be significantly bigger - for example, my caliper puts an Emax 2306 at 27.73mm and a DYS 1306 at 18.00mm. Any outrunner mounted behind a firewall will need clearance for the leads, so keep that in mind as well.

There's a Great Planes planetary box that's a little cheaper than the Reisenauer option, but the specs list it at 28mm outside. It may be slightly narrower at the firewall end, but that may or may not be narrow enough.

Oops. You're right... But still, quad motors will get you a wider range of options than airplane motors.

One of these will fit..... https://www.espritmodel.com/hacker-b...ss-motors.aspx

I think your right! Not sure if it’s in stock but that seems like a good price point and hoping the lowest I’ve of around 3000 would not be too high. The stat says 12x6 folder prop do I could probably make it work.

It's an older model motor. Contact Hacker, you may be able to special order one. They pop up in the classifieds once in a while too. https://hackermotorusa.com/product-c...inrunners/b20/

Good suggestion thanks!!

Here's one... https://www.ebay.com/itm/39313989822...gAAOSw2QlgLuWr

Hi Walter,

an AXI 2220/20 GOLD LINE V2 Long would be also a solution. Using 3S and an Aeronaut Cam Carbon (ACC) folding propeller 13x8 with a 42 mm center hub , the current is about 18 A at 50 % SoC. Sure a geard inrunner has a better motor efficiency, but more expensive.

https://www.modelmotors.cz/product/detail/505/

Regards
Micha

Axi makes a fine motor, but 135 watts might be a little underpowered.

Originally Posted by Tahoed

Axi makes a fine motor, but 135 watts might be a little underpowered.

For a vintage glider with a low wingload it will be sufficient from my point of view. With a MTOW of 50 ounces and an estimated propeller efficiency of 0.7, the climb rate is approximately:

135 W * 0.7 / (1.42 kg * 9.81 m/s^2) equal 6.8 m/sec. Assuming a sink rate of 1 m/sec for drag losses, the climb rate is about 6 m/sec.

Regards
Micha

Originally Posted by Tahoed

Here's one... https://www.ebay.com/itm/39313989822...gAAOSw2QlgLuWr

Technical Data of a Hacker B20 18L 3080KV 4:1

3S Lipo and Prop 12x6,5 at 17A

max. 220W (15 sec.)
Idel current @ 8,4V 0,66A
Motor R 0,085 Ohm
KV 3086 U/min-1
Weight 69g

https://www.hacker-motor-shop.com/El...0007700&p=2072

Not much more power.

Regards
Micha

Is this, or similar, an option? Or use motor with a smaller diameter gearbox?
www.leomotion.com/ki/en/Zubehoer-Motoren.html