Electric setup problem

[Mal Quelch]

Simuk, looking at your picture it looks like the prop is fitted directly up against the "bell" of the motor, if this is the case then it is possible that when you tighten the prop nut you can actually pull the shaft through the motor itself and pull the rear circlip up tight to the bearing. Does the prop still turn freely? If it is stiff it will pull a lot more current, the watts will appear higher, and not be providing the thrust you expect. Either fit a nut each side of the prop with washers etc, further away from the bell  or preferably use a proper taper type prop adapter. At least that way all the power taken from the battery will be getting to the prop and not over stressing the bearings. Hope this helps.

[Simon UK]

Mal thanks very much, i was considering adding a nut each side of the prop. And what you have said makes total sense now i look at it.

 

Cheers pal

[Mal Quelch]

Thats ok , not a problem as i have been there myself I have a few of the early style with the shaft just a knurled fit in the rotor and the first time I used one it did just that, a new bearing was called for and its just fine now.

[Simon Chaddock]

Simuk

Got to chip in here. I have done quite a bit of development with a Wing Dragon 4.

With a 3s LiPo you should definitely be using a 7x4 and even that will work that particular motor quite hard.

I used a slightly bigger Emax 2812 with a 7x4 and 1500mAh 3s LiPo.

The Wing Dragon really needs a fine pitch prop as it flies so slowly.

Compared to original NiMh and 480 brushed motor you will get both a substantial increase in thrust and save quite a bit of weight (650gm all up?).

I went on to build a series of lighter wings & tails combined with micro servos. I eventually got down to just 450gm with the result that both its performance and duration are in a different league!

Keep us posted on how you get on.

[Simon Chaddock]

Simuk

Just read all the threads again.

I agree with Timbo as it certainly looks to me that the prop in your picture is the wrong way round for a pusher. The under cambered prop surface must face the rear.

As you have it will be rather inefficient and will not produce the maximum thrust for the current draw.

[Tim Mackey]

Simon, the loong max 2s pack I showed in the picture is quite "long" - but then its way more capacity than you need I expect. Most if not all sites will give the dimensions before you purchase.

[Simon UK]

Simon

 

Aha! A fellow Wing Dragoner, very glad to know you are here Simon. Many thanks for the information on the prop size also. I fixed the orientation on the 7x6 and it puts out an amazing amount of thrust, so you guys where quite correct I did have it on the wrong way round (you live and learn I guess). 

 

Timbo on the subject of the 2 cells, I have read other Wing Dragon owners that say running with only 2 cells makes the plane perform almost the same as the stock brushed motor. Does this sound correct to you?

 

As to the size I have noticed that most Lipo sellers state dimensions which will help me find the right battery should I choose to try 2 cells.

 

Cheers Guys

Edited By Simuk on 12/11/2009 13:38:09

[Tim Mackey]

2 cell will produce far less power than 3s yes - as to it being the same as the "stock brushed motor" well that depends almost entirely on the wind of the motor and the prop you use. It depends what you want it to do... 3s wll be fast and thirsty, 2s will be slower and due to low current consumption will fly a lot longer

[Simon UK]

Hmm, I think at the price of those Loong Max batteries I can afford to buy one and try it.

 

Hoefully the GC webiste will get sorted out over the next day or so.

 

Thanks Timbo

[Simon Chaddock]

Simuk

A 2s will produce broadly the same thrust as the stock brushed set up but it does ultimately depend on the motor you use.

A LiPo can put out a lot of amps so even at 7.4 volts the total output can still be quite generous and as a brushless is more efficient every watt from the battery is converted into greater thrust. Coupled with the weight saving the performance and duration will be considerably improved.

 

I have posted before but this heavily modified Wing Dragon has a 7x6 prop and a 2s.

But then it is a huge 5000mAh 2s!

Even so it only weighs 600 gms so at full power it has more performance than a stock WD. (like 7 consecutive loops straight off the climb)

However with careful use of the throttle it can fly for a mind numming 96 minutes (yes 1hour 36 mins) on one charge.

Let me know if you need any help or advice.

Have lots of fun with your Wing Dragon, I still do with mine!

[Simon UK]

96 minutes that’s mad, in a good way of course. I think I will try one of those 2300 Tipple packs. And see how long I can get out of it.

 

Simon have you ever tried mounting the Rudder and Elevator Servos in the side of the Fuzz? I have seen it done and it could be the answer to my long battery pack problem.

 

Any advice as always is very gratefully received

Edited By Simuk on 12/11/2009 23:22:23

[Simon Chaddock]

Simuk

I did say my Endurance Wing Dragon was highly modified - it has no servos in the fuselage at all!

Let me explain:

First it has quite strong differential aileron action (more up than down) done mechanically by angling the servo arm 45 degrees forward. This means that a rudder is not required for normal flying so it has no rudder servo.

It has a T tail allowing the elevator servo (3.7gm) to be buried in the fin. The servo leads run inside the boom up to the radio.

Obviously a 5000mAh battery is quite a bit heavier than normal so to get the CofG right the radio goes in the nose, the ESC is taped to the side of the fuselage and the battery is on the cockpit floor.

These are rather extreme mods but the length of the battery (160mm in my case) is no problem.
 

 

[Simon Chaddock]

Simuk

I had to go to work before I finished the last post.

The "Endurance" Wing Dragon was really the end of the development. It started rather more modestly but some of them might be of interest to you.

First the aileron servos were buried deeper into the wing so they did not stick out underneath so much.

Then came differential ailerons which allowed the rather stiff bottom tape hinge to be replaced by a much more flexible top surface Sellotape one.

The fully sunken servo with its horn set forward 45 degrees.

Although no weight saving there was a small reduction in drag but more importantly the differential ailerons significantly improved the flight characteristics.

Then came the weight reduction programme.

A built up depron wing (Clark Y section) of similar size but only half the weight. Now it was beginning to fly really well.

Then came the 3s LiPo but it burnt out the 480 brushed motor after just a few flights.

So on to the brushless out runner, which is still being used. Compared to the original the performance was now sparkling with an endurance of up to 20 minutes.

As the differential ailerons made the rudder redundant why not a lightweight V tail to balance the removal of the rudder servo (the tail plane was always getting damaged anyway), along with a streamlined cockpit canopy.

The last rebuild with new lighter wing tips and slightly bigger ailerons.

Still exactly Wing Dragon size but now seriously aerobatic, it could climb almost vertically to 300' in 20 seconds and then glide power off for another 60.

Next came flaps but that is another story.

I hope this gives you a few ideas.

Edited By Simon Chaddock on 13/11/2009 21:27:05

[Simon UK]

Fantastic stuff Simon, really nice to see what can be done with a little imagination.

 

On a slightly different note I managed to pick up a couple of new props, I also got my El cheapo productions present - dremel clone out and cut the threaded shaft from the motor.

 

I bought a proper (no pun intended) prop adapter and fitted the two new propellers results are bellow.

 

New Propeller mounting

 

Readings on 3 cell Lipo at full throttle 6x4 prop

 

Readings on 3 cell Lipo at full throttle 5x5 prop

 

Now a couple of Questions, i worked out the above 6x4 prop would give me roughly 8 minutes at the shown 10amps, on a 1350 3cell Lipo. Is my maths anywhere near correct?

 

Next if you had to which of these props would you go with for general useage?

 

Lastly (for the meantime :P) these are not pusher props and can only be fitted on the shaft one way, can i reverse the direction of the motor to get the correct thrust for a pusher or will i have to try to mount them backwards?

 

Cheers Guys

Edited By Simuk on 14/11/2009 16:22:40

Edited By Simuk on 14/11/2009 16:26:12

[Tim Mackey]

Thats the whole point of electric motors and props - there are no pushers ( except twins and thats another story )

That prop still looks wrong to me. The writing on the blades must be facing forward - into the direction the model will be travelling - no matter if its a tractor style model ( the prop pulls ) or a pusher style ( prop pushes ) 

On your pusher model, look "down" the model from its nose at the prop....you should be seeing the writing /numbers on the blades. Now, wire the motor ( swop any two of  the 3  motor wires with each other ) so that again as viewed from the front, the prop is spinning anti-clockwise.

[Tim Mackey]

Your 1.35A battery ( the voltage is irrelevant ) at 9.5A will last approx 7 mins.

(  9.5 / 1.3  )

However in the air two things happen,

1)the current at WOT comes down as the prop "unloads" and

2) You rarely fly at WOT the whole flight.

I usually add around 30% to the calcs to get a rough idea of duration, but you should use a timer, and start to land as soon as it beeps. do NOT wait for the LVC to kick in.

As soon as the motor revs start to drop off a bit - get landing!

Edited By Timbo - Administrator on 14/11/2009 16:39:45

[Tim Mackey]

The 6 x 4 prop will give you slightly more thrust and a little less speed than the 5 X 5

You pays yer money and takes and choice ( mine would be 6 X 4 )

[Andy Gates]

Timbo is right, that APC E prop is on back to front, sorry Simuk.

 

That will mean all the figures you aquired during testing will now be  wrong so you will need to run your tests again.

 

It will be interesting to see how much the test results differ.

[Simon UK]

Ok i hope i'm not boring you all to much!

 

Here are my latest pic's Propeller on right way round this time

 

New prop adapter with prop on right way, thrust is an instant improvement

 6x4 prop on meter

5x5 prop on meter

 

Any thoughts?

 

Cheers Guys

Simon

 

[Tim Mackey]

You've had mine.

[Simon UK]

6x4 it is then thanks Timbo.

 

I have a 2 celll on the way to try with the 8x6 aswell.

 

[Simon Chaddock]

Simuk

Unless you have raised the motor centre line an 8x6 won't clear the tail boom. Do you mean a 7x6 on the 2s?

Have you flown the 6x4 yet?

[Simon UK]

Simon

 

Yes i ment a 7x6 doh!

 

I haven't flown any brushless setup yet, i am waiting on some semi decent servos arriving, i decided while i was at it i would move the Rudder and Elevator Servos to the side of the fuselage.

 

This means i can stick a big Lipo in the plane or i may experiment with 3 x A123 cells aswell.

 

I have a few of those spare from another Electric conversion i'm doing.

[Simon Chaddock]

Simuk

When you say "to the side of the fuselage" do you mean just further apart or actually outside?

I know the WD is pretty tolerant but in general planes fly better (and use less power) the more streamlined they are.

Could you not just move the servos back a bit to give yourself room for the battery. After all your brushless motor is quite a bit lighter than the original 480 so you will need to adjust things a bit to maintain the same CofG. Just a thought.

[Simon UK]

Simon

 

To be honest i am not to worried about streamlining, i am not after every last bit of performance from the plane. I am far more interested in getting  good performance and to make it more solid and crash resistant.

Where the servos are located as standard is fine if you want to stay with low mah batteries, but if i move them to the outside (sides) of the fuselage then i make a pretty serious improvement in battery space. It also allows me to pad out the nose a little better (most likely place to take a hard knock imo).

Also due to the limited access to the insides of the fuzz i could'nt see moving them back from where they are currently located as being very viable.

 

Could i ask if you reinforced any areas of your WD before you stripped it down to use only the Fuzz from standard? I have heard the wing is coverable and some carbon fibre could help the tail feathers, have you any experince with these areas on stock items?

 

Cheers

Simon (simuk)