G’day Members,
I have not been idle since going into lockdown or whatever they call this mess we are in.
I have had a Spirit 100″ kit in the shed for many years and it has been one of those projects I have wanting to complete.
The glider has a 2.5 meter wingspan and according to the box has a flying weight of 1.8 kg. That is when set up to launch with a bungee.
I am thinking of setting it up with an electric combo. Either up front as a replacement for the nose cone, with a folding prop or perhaps on a pod as Glen has done with one of his gliders.
I don’t speak much electric so I am really interested to get advice from those more experience in that area, as to what size motor, prop, speedie & battery that I should use.
I will post some pics of the bones of the model when I get a bit further down the track. It is good to get back to building with sticks and glue and I reckon they look really great without the covering.
I probably would have the glider nearing completion by now but She Who Must Be Obeyed has had to put her business into hibernation and has been coming up with all these jobs that she claims I have been promising to do for the last 20 something years. Like painting the ensuite in her salon that we built about 25 years ago. It was still unpainted. I admit that I did say I would do it, just not when.
Cheers Greg
Hi Greg, I’ve got some old RC magazines which contain articles on selecting motor/speedy/battery combos for planes which I’ll scan. Also a few years ago I had a Radian Pro glider (regrettably now gone to that big airfield in the sky) which was a 2M wingspan foamy weighing around 1 Kg or so with motor and battery. I salvaged the motor, folding prop, spinner and esc from the Radian and am not using any of these so you are welcome to have them if they are of any use.
I mis-wrote above – the motor and esc seem to have disappeared but I do have an 11×6 Graupner folding prop and spinner if that’s of any help – let me know. Scans of articles are underway.
From memory the Radian Pro motor was around 900kv and the esc was about 30amps. I found this article (https://www.hobbywarehouse.com.au/articles/how-to-choose-the-perfect-brushless-rc-motor.html) which might be relevant
Hi Greg
The general rule for a reasonable power/weight ratio is about 100 watts per pound weight. You should use a folding prop which I can probably help you with as I have some spares. The motor should have a Kv of 1000 or less and be able to handle the power you need (watts).
Hi Greg
My threepence worth:
It sounds like similar dimensions to my ASW 28 but strangely a bit heavier ?
For folding prop make sure ESC can handle engine braking (Apparently not all can, Turnigy Plush do- I have a programming card if you need it)
Stick to nose mounted motor (This advice given free from the club/world expert in launching disasters)
Neill’s Radian stuff should be just great (Make sure he doesn’t forget to give you the aileron controls).
I use a 2200 3s in the ASW28
Cheers
Ray T
Hi Greg
Have you tried using an online calculator? I use Ecalc (https://ecalc.ch/motorcalc.php), and it’s excellent for trying lots of different combinations of batteries, ESCs , motors and props.
The results are usually close to real world values.
I often choose a motor/prop combo that will give a thrust to weight ratio of about 1.5 (give or take a bit). After that I choose the appropriate ESC and then battery to balance the plane.
Altering the prop diameter and pitch then gives you a speed estimate for the plane, and whether (and/or, by how much) the prop will be stalled under static thrust (i.e. at launch).
There’s other ways to arrive at the desired components using Ecalc….this is just one example.
Cheers
Jeremy
Thanks for that valuable information guys.
I will do some homework when I get let off the hard labour.