wing loading

Seems OK to me

What's the AUW and the power train?

If it's a nasty speed 600 on a 8x4.5 folder, it isn't really up to more than a couple of lb. Solution is 8.4v :-)

The message from The Natural Philosopher contains these words:

Problem was the design of the nose end which isnt a large enough diameter for a 540/600 motor, the original design is a pure glider and just to help it along a bit I decided to stick a motor into it but could only squeeze a Race 480 in there with a 7x6 folding prop, I have plenty od spare blade sets and could fit 8x6 if the motor will take it, the only redesign of the nose end I could do was add a 'chin' intake to cool the motor. All up weight ready to launch is just 1200 grams which is about 100 grams more than I had hoped but it is built a bit like a Sherman tank and the wing forward of the box mainspar is filled with urethane foam which stiffened it up considerably, when calculating wing loading do you take the tailplane into account because I havnt, I have only used the area of the mainplane,

regards, Terry

Well its not gonna break any records..whats a race 480 good for..20A and on 6v..120W..

And 1200 grams...is a bit shy of 3lb...its gonna scrape into the air just about.

Will only affect stall speed calcs anyway, and you have adequate pitch speed..what really counts is power to weight, and that is marginal.

I think it will gain altitude, but you probably won't be able to get to decent altitude more than twice on that pack.

If that.

Also will need a firm chuck to get airborne..I haven't got Motocalc running on this setup, but I estimate stall speed around 18mph.

Put a brushless motor in it! MUCH more power than the old brushed ones.

The message from The Natural Philosopher contains these words:

Hi, the idea was to fly it as a glider and only use the motor in emergencies like when I screw up and need a bit of help with forward momentum sort of thing, I will use a bungee launch off a ramp so getting off the deck will be no problem,

regards, Terry

The message from "Jim" contains these words:

Hi Jim, could well do as I have five of them and three are about the size to take a 7'' or 8'' prop depending on pitch, also have three ESC's in the box somewhere and changing the motor was taken into account and I extended the length of the canopy so that the motor could be removed through the cockpit opening but would need to construct a different method of mounting the motor but thats no problem,

regards, Terry

Don't know how your climb rate will be but at that wing loading, it'll be a floater. Cheers -- Lyman

"Terence Lynock (MSW)" Is 13.4 oz per sq ft wing loading all up with 7.2v

In article , Terence Lynock (MSW) wrote: | The message | from The Natural Philosopher contains these words: | | > What's the AUW and the power train? | | > If it's a nasty speed 600 on a 8x4.5 folder, it isn't really up to more | > than a couple of lb. Solution is 8.4v :-) | | Problem was the design of the nose end which isnt a large enough | diameter for a 540/600 motor, the original design is a pure glider and | just to help it along a bit I decided to stick a motor into it but could | only squeeze a Race 480 in there with a 7x6 folding prop, I have plenty | od spare blade sets and could fit 8x6 if the motor will take it, the | only redesign of the nose end I could do was add a 'chin' intake to cool | the motor.

Is that motor direct drive or is there a gear box?

I wonder if your prop is too big for that motor. I haven't done the math, however. If it's direct drive, I suspect you're going to push the motor too hard. Measure the current it draws at full throttle, and if it's higher than the rating of the motor, get a smaller prop or a gear box. And really, rather than a gear box, you might want to spend your money on a low Kv brushless motor instead.

In any event, gliders benefit from slow, big props. Using a little, fast prop will work too but is much more inefficient.

It does sound like your plane is quite heavy. For a glider, heavy is generally OK if there is sufficient lift (the extra speed does help you find lift, especially if it's windy), but for an electric glider your motor has to get that all up there too and it really hurts there.

It's quite possible that it won't develop enough thrust to go up at all if my guess is right about the motor and prop. But give it a shot, once you've measured the current drawn by the motor anyways. Or run it all through motocalc and see what it says?

| when calculating wing loading do you take the tailplane into account

Usually not.