Monday, 10 December 2012

28mm can inrunners with gearbox for Gliders

We have so many request for information about our motor project for gliders I thought I’d put up the latest information here.

Even if you know your Kv from your C ratings, gliders are a special case for E power. There is a very simple reason for this- they are skinny and the perfect power set up might not fit the beautiful slim fuse you wanted it for despite pouring over Ecalcs to design your perfect set up!
Reisenuaer Gearbox and Leopard Motor 

The realisation that most glider folk venturing into E power want predominantly a get up system but soon discover if that takes 20 to 30s it’s very disappointing especially if you want more than say 5-6 climb outs. Then lower power isn't that light as you need lipos big enough to run a motor for around 3 mins.

That was really the only way at one time but lipos are getting so good now it's even less of a reason to do it this way, especially in a top of the line F3F/B type 3m. Fast climbs above 30m per second with 8 second or less climbs to 250m and less than a minute motor run times in total; a third of the capacity is required compared to the slow climb. This is a better light weight strategy. A third smaller lipos is a significant reduction in the overall weight and space needed for your glider power set up and more than makes up for a bigger more powerful motor.  In any case it’s a lot more fun this way and a great excuse to make your electric glider exciting!   

So a reasonably powerful motor can be the basis of electric glider power set ups but we still come back to the space restrictions with gliders. Small is easy but powerful, light and efficient is harder to find. There are a number of 28mm diameter motors both in runner and out runners using gearboxes for gliders. Efficiency for these is good up to about 700w or so but generally best around the 500w level. So if diameter is restricted then bigger can only mean longer. Long case motors with bigger magnets and stators is rare.
This is 4s motor
Shafts now made with 3.17mm dia.

Cooling holes front and rear plate
We have been working with a motor manufacturer to produce in runners based on 28mm diameter and 64mm can lengths. These are longer than the average and have now been especially made for us with 3.17mm output shafts. This has allowed us to up the gear ratio to 5:1 using top quality Reisenuaer gearboxes allowing larger more efficient props to be used. They are more powerful than most 28mm diameter motors available and high quality 4 pole motors.

The combination is expected to retail at £163 which is with the gearbox installed and tested in our workshops.   

The motors are made by Leopard Hobby, who sell motors in their own brand and OEM high quality brands. They are gaining a great reputation in the electric RC boat and car market and now helping us develope motors for our gliders.

Motors alone weigh 180g and with Micro Edition 5:1 Reisenuaer gearbox fully assembled with adaptor flange, approx 210g.        

Although we will introduce different Kv motors to suit 3s and 6s (and 5s), the 4s set up gives the broadest applications and a good compromise with efficiency and power. In this way upping the power with higher voltage using different Kv motors is not only efficient use of power but also keeps the cost of Esc reasonable as 100a is all you really need. This can support a 2Kw system on 6s. The difference in cost between a 100a esc and 150a or 200a+ doubles and triples! So if you want to run at the top end of these motors in terms of power go 6s and at the bottom range then 3s. The cost of the motor and esc is the same.  

We tested the 4s motor (2730Kv) on our New Air One electric previously motored with a Hacker B50 12s geared with approx 1kw output (not static input, which overstates the real situation!) in the air. The new motor on 17x13 gave the same power (approx 1050w) but weighs 50g less. The lightest we fly this is 2.3kg using the new motor and 4s TP 1300mah 65c. The non electric glider is 2.2kg empty. The difference in weight is getting tiny!
Reisenuaer Micro Edition planetary gearbox,  absolute top quality engineering.

Of course a smaller, lighter plane like the upcoming Schwing electric is going to be pretty outrageous with this motor and you can be certain our prototypes will be using them.

Electric gliders are getting more popular. A powerful lightweight system isn’t wildly expensive not compared to a high power competition F5B electric set up. Anything previously from about 1kw to 2kw+ was heading that way if indeed it would fit in a skinny glider but with these new motors and gearboxes from Sloperacer are great value and will open up the opportunity for more electric gliders which are light and yet still have hotliner performance (some say a hotliner needs a minimum of just 150w per lb which these motors can provide). They will also allow many more glider conversions especially for F3B electric planes when skinny and around 1kw are the main requirements. Of course many manufacturer’s dedicated electric gliders can be powered too especially ones designed around 28mm diameter cans. You might not have thought you would need this much power and even the purists who never thought they would ever have an electric plane seem to be impressed by our test models, especially after they see the climb rate and then pick up the planes and see how light they are!

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