Brushed Motors compared to Brushless

[leccyflyer]

I think that's what Pat is saying in that last sentence.

[PatMc]

56 minutes ago, MattyB said:

All true for a more modern higher performance e-glider, but I am not so sure it holds as true for these models. They do not have the right sections for the kind of “fly to the target spot under power” stuff that you can do with a modern composite model.

It works fine with my 10yo Easyglider Pro, my Igor (bitsa made from an ancient St Leonards Models Super Nova wings from cut down to 6ft & bolted on a spare Protech Unlimited plastic fuselage) & my OD 2.8m span RelaxE open structure wings with boxy fuselage that's been converted from brushed motor + nicads to BL + lipo. 

RelaxE with geared brushed motor & nicads.

 

Igor

 

RelaxE with BL motor & lipo. Lengthened nose because battery under hatch.

 

Edited March 20, 2021 by PatMc

[PatMc]

57 minutes ago, leccyflyer said:

I think that's what Pat is saying in that last sentence.

Leccy, just to clarify. I was suggesting that if the kits EarlyBird has been given were equipped to the higher power rating they would be capable of flying to the target area within 30 secs or so.  

[leccyflyer]

28 minutes ago, PatMc said:

Leccy, just to clarify. I was suggesting that if the kits EarlyBird has been given were equipped to the higher power rating they would be capable of flying to the target area within 30 secs or so.  

Apologies, I misunderstood. I thought that you were agreeing that the role of the power train for these models was just to get the glider up there. to begin hunting for thermals.

 

[J D 8]

Having recently converted an old Easy Pigeon to brushless I would say it was a fair bit of bother to fit the outrunner in the nose [ nearly put it on the outside ] of the plastic fuselage along with a chunk of lead and fitting the lipo far enough forward too limit the lead load. If doing it again I would stick with original motor.

[Cuban8]

IIRC from the 1980s and early 1990s, quite a few E-gliders were produced and were a certain way to have success with electric flight and not spend a fortune. Electrafly and Electra as have been mentioned along with Balsa Cabin Sonata-E and Flair Volture. Many others that came and went from small manufacturers. They were never anything more than self launching soarers and a minute or so on their modest power would get you well up to bungee or hand tow height, or higher in good conditions.

I managed to break the magic hour duration with a Sonata-E at Fairlop over thirty years ago (the original Cliff Goater version with the widened fuz) that I bought from the Balsa Cabin stand at Sandown for around twenty quid at the time. No box, all the bits came in a long clear plastic bag!  It was heavy on seven sub-Cs, separate RX battery, electronic switch and 'Speed 600' motor, but did have mini Futaba servos that in themselves cost almost as much as all the rest put together and were not that small or light anyway. The scary thing was when you found good lift and the smallish model would climb rapidly to a dot. No air brakes, so that had to be factored in if you didn't want to risk losing sight of the model, and inadvertently over-speeding the heavily laden airframe at height would be disasterous.

Mostly a comfortable twenty minutes could be got from a charge which wasn't too bad. I am tempted to put another one on my to do list as I rather fancy the simplicity of the build and the potential performance improvement with modern gear.

Edited March 21, 2021 by Cuban8

[Geoff S]

I was once flying my Sonata E in a local field a few minutes walk away from home and hooked a thermal not long before lunchtime.  I could also see a line of fair weather cumulus clouds up to windward indicating more lift on the way.  So instead of seeking lift I was desperately trying to get out of it.  I managed to fly fast enough with enough down elevator to get down and eat ?   This was with a 7 cell NiCad (or NiMH) and a 600 brushed motor.  They fly very well.

 

I bought my kit from a Sandown show as well but it was in a box and cost about £30 IIRC.  The main difficulty was trying to fit the motor in the narrow nose. IIRC it was suggested that a motor shaft extension should be used but I couldn't think of a way of doing it successfully.  I ended up cutting the nose short.

[Simon Chaddock]

I am not suggesting it is the answer to everything but you can put an out runner in a narrow nose.

Just a bit of foam. The prop adaptor goes inside the spinner leaving a small gap so air gets to the stator. The 'naked' bell keeps the magnets cool too. ?

Its a 40" glider (its under 250 g all up) and can cruise under power for an hour - just.

[Dickw]

The big advantage of brushed motors is that they can be controlled by a simple servo driven switch.

Back in 1987 I built a 100" soarer with a large Geist (early german make) brushed motor powered by 10 x 1200 mAh nicads and driving a 12x6 folding prop. This was very advanced for this country at that time and, as there didn't seem to be anything readily available for such a beast, I ended up building my own switch - you can see it just behind the motor in the photo.

Two 20 amp microswitches were held in a frame and operated by cams driven by a servo. The first switch fed through a resistor to limit the initial power and give the prop chance to open, and the second switch shorted out the the resistance a fraction of a second later to give full power. In the OFF position the motor was shorted out so it acted as a prop brake.

Despite the fact that the measured current was about 50 amps the20 amp microswitches lasted for several years regular use.

 

I wouldn't want go back to brushed motors, but they worked OK when we had nothing else.

 

Dick

 

 

[Colin Bernard]

I converted my Electra to brushless about 5 years ago and it's worked well. (You can see the Electra in my avatar.)

[EarlyBird]

I have checked the other gliders that I got in a bundle. One has a canned brushless motor and another has a brushless motor and speed controller.

 

I have all the options available to me. ?

 

I am starting with the Electra Fly by converting it to brushless as I have the motor and ESC. This will be flown first and will be my first 3 channel model ever, scary no ailerons.

?

I have an MPX Easy Star again 3 channel which could be my first.

To me they are both disposable test models.

 

Then there is the Electra to build as brushless and finally a Great Planes Bird of Time, both of which I will treasure.

 

This all started when I said to a club mate 'I have always wanted to fly gliders' fortuitously he also wanted to down size and said he had an MPX Heron kit new still in it's box.

'I will have it' I said. He then said also a BoT NIB and ....

 

I think this has sorted my flying for at least one summer. ? 

 

Thanks everyone for the help which is very much appreciated.

 

 

 

[Sonofpincher]

Fascinating stuff, all about gliders with brushed motors. I don't have much experience with gliders, but started with electric 25 years ago, in the Speed400 with MFA gearbox era. Now use brushless & lipos, BUT, still use small brushed geared GWS in twins and my Lancaster! I have a thrust test rig, and they give efficiencies close to brushless, and only need one ESC! I wish I could still get the GWS twin motor geared unit. I have to admit, four geared brushed motors do not sound much like 4 Merlin's!

[EarlyBird]

Welcome @SonofpincherElectric will never sound like a Merlin but then nothing else does. 

[leccyflyer]

1 hour ago, EarlyBird said:

Welcome @SonofpincherElectric will never sound like a Merlin but then nothing else does. 

On the contrary I fully expect my Warbirds Replicas Mustang to sound just like a Merlin, courtesy of the supplied Mr RC Sound module. ?