Beafing up my Auto - G

[Malcolm - coolwind.co.uk]

Posted by Mowerman on 22/10/2013 19:49:27:

The couple of times Mine actually flew were not very sucessfull, took off OK but having reached about 10 feet would not climb any further.

Any comments?

Edited By Mowerman on 22/10/2013 19:51:01

Mowerman,

I've had this with one of mine, and concluded that the head bearing was binding and not allowing the rotors to get up to proper flying speed, although i've not fully investigated or repaired it since,

Malcolm

[Tom Wright 2]

Roy

I have just done a watt meter test on my G1 and get 175 Watts reducing to 150 Watts , mind you this is on a two blade 10 x 6 . I assume, as Malcolm suggested , you had verified the the rotors were free running with no hit of binding, so is it possible that up elevator was applied before full flying speed was reached ? if by chance this was the case then the model would have probably started sinking tail down ,and or unexpectedly yawed and rolled .

It sounds if your power is on the low side , the lipo has been eliminated , and as the motors seem pretty reliable that leaves the ESC , or the prop slipping.

Tom.

[Foamie Dave]

Posted by Mowerman on 22/10/2013 19:49:27:

The couple of times Mine actually flew were not very successful, took off OK but having reached about 10 feet would not climb any further.

Any comments?

Was it the MK1 or the later version with pre-rotator ?. My early one flew like a peach until I retro-fitted the new pre-rotator head assembly.

After that I needed to pin the throttle and fly it like a fixed winger to get anywhere. Think it may have been a combination of the additional weight of the head unit and additional gubbins and maybe friction / binding of the head. unit.

[Mowerman]

Dave Tom Malcolm

Thanks for your replies and suggestions, sounds like I am a bit down on power.

I will try a different ECS and prop.

In the mean time my blades are re-built using the original plastic leading edge. Removing the old foam was a bit of a messy job but got there in the end.

Ballancing was almost a non event as they came out pretty near. This leaves me with the AJ blades in reserve (perhaps a crane fly in the future)

[Mowerman]

Following the above suggestions I have changed the ESC and now get 160W after half a min (still standard prop).

Thanks chaps

[Foamie Dave]

Great idea with the HK blade mod.

Think I'll do mine - Ive plenty of battle scarred bits left over from "test flights"

[Tom Wright 2]

My solution for a mast tidy up is 3mm depron attached, to the inside and outside mast faces. This works well and the material is very light.

Tom.

[Stephen Jones]

Hi ,

Not sure if this is the right place to post inquire about my Auto G , But here goes ,

Ok , i bought a second hand Auto G for £10 as i have been wanting to fly a Auto gyro for some time now but never managed to muster up the guts to build one , i bought plans and have some free ones but some how never got around to it .

So when i saw this second hand crashed Auto G For £10 with two spare heads i thought well now is the time to give it a go if the airframe is no good at least i will have the heads to make a start on one of the plans i have .

So the Auto G had no radio gear , motor or wheels and the blades where broken in short it had been stripped , but i had most of the gear to go in it and i could Easley repair the airframe .

So i have got some replacement Blades From A J Blades and the replacement Flapper Plate from cool wind all fitted , the airframe has glued back together nicely i have made a new battery hatch from 5mm depron and glued some ply to the front end as a motor mount as the original one was broken .

All the radio gear is in now its almost ready to fly but reading through the many posts there seems to be some confusion over the new blade length and balanced point .

Here are my specs , Auw 628 g , battery 3s 1300ma , 30amp Esc , Motor CF2215 1200kv 25a pulling 180 watt on a 10x6e , My blades are 33mm longer than the stock blades and my balanced point is on the Centre of the front mast at the point where it is glued into the body .

Before i take it out for a crash / fly , does everything seem in order to you guys ,

Any help here would be greatly appreciated ,

Cheers Steve ,

[Stephen Jones]

Opps here i confuse myself ,

I meant to say My total blade length from the Centre flapper plate to the tip of my blades is 33mm longer than the original stock blades and hub if that makes more sense .

And my blades do not hit the fin .

Steve ,

[Tom Wright 2]

Hi Steve

If your motor is this one it would be as well to check the weight against the stock model motor. As for direct comparisons my blades are 402 mm, so very close to yours .

The hang angle when suspended from the rotor bolt is 10-12 degrees BTW if a pivot point is located at the C/G location you give for your model then the nose is around 45 degrees down.

4-5 degrees motor down thrust with a little right thrust should be about right , if all other factors are correct then the model should fly ,how it flies, and how well is a matter of individual perception and could depend on previous successful AG experience and ability to determine best trim, but my conversion literally flew well from the first hand launch although some down trim was needed, but this could be due to the less than 5 degrees down thrust set at the time of the first appraisal.

If you need any more direct comparisons just shout or I can go fly mine again for some current feed back .Best of luck if you maiden in the mean time and do let us know how it goes.

Tom.

[Tom Wright 2]

Posted by Stephen Jones on 23/04/2014 22:50:14:

Opps here i confuse myself ,

I meant to say My total blade length from the Centre flapper plate to the tip of my blades is 33mm longer than the original stock blades and hub if that makes more sense .

And my blades do not hit the fin .

Steve ,

Just for information Steve my model when measured from the plate centre to the blade tip is 420 mm.

Tom.

[Stephen Jones]

Thank`s Tom ,

you are without doubt a very helpful man ,

My blades are 435mm from Centre to tip , i also forgot to mention my servos two 9g for rudder and elevator and one tower pro 995 for the roll , The motor is Emax CF 2215 ,

is balance done with blades on or of as if the two blades are forward .?

mine seems tail heavy balanced by holding the body at the forward root of mast and my battery is in place .

Cheers Steve ,

[Tom Wright 2]

Steve

I could be wrong but I suspect the CF2215 is lighter than the HK stock motor ,which is quite a lump for a couple of hundred Watts power .

If your model is 10-15 degrees nose down when suspended by the rotor bolt it should be OK.

The actual C/G as you describe it at the mast base is usually used as fixed point to relate the thrust line to, so the much maligned but more often used hang check from the plate centre bolt should be sufficient if the motor has some down thrust. That's my take anyway but it's a while since I have thought about such things ...ten models later! so I will be quite happy to be corrected.

If the model is set up like mine then it must fly , that is unless I have missed a major change in the laws of physics . I have now dug the model from the hanger so fire away if I can help.

Tom.

PS Thanks for the photo ....looking good to go if the motor weight is correct,.

 

Edited By Tom Wright 2 on 24/04/2014 00:50:15

Edited By Tom Wright 2 on 24/04/2014 00:51:38

[Stephen Jones]

Cheers Tom ,

I have check it`s balance by holding the rotor bolt with the rotor on and off and i have the nose pointing down .

Also i prop the tail boom until it was level using a sprit level clipped to the boom and found the motor was at zero, so i have now add some down and right thrust now .

Do you think my blade length will be fine or do you think that they may strike the rudder on landing ? being 15mm longer than yours .

Also how much controls do you recommend for a complete beginner like me .

Cheers Steve ,

[Tom Wright 2]

Steve

If you force a blade down to to within 1/4" of the fin base it should not touch any part of the fin above that point. If you check this then it should be no problem in flight .

I flew my model today and can confirm the rudder and elevator throws were plus and minus 15 mm ,the rotor moved plus and minus 70 mm measured at the tip.

The authority using roll alone was quite sedate and sometimes needed a touch of rudder to get a balanced turn , the trick is not to let the nose drop during turns so the elevator needs to be used in proportion to the angle of bank and sufficiently to keep the nose tracking around the horizon.

Looking from the rear the roll trim is 3-4 degrees left . Be aware that these settings will not guarantee your model will fly correctly as other small variations will require correct trimming before the model becomes relatively easy to fly.

If you can find a experienced AG pilot to carry out the first flights and get the model trimmed then as a first timer you will be more likely to get some air time from the off.

Regards

Tom.

[Stephen Jones]

Cheers for the info Tom ,

I will need to cut some more off the tips of my blades , as i suspected ,

I am on my own with this one as there are no AG pilots at are club and i have never seen one fly at are field , Not even the full sized one that inexpediently turned up one day ,

Cheers Steve ,

[Tom Wright 2]

Steve

Just as a foot note to my comments ,my model is currently set up with 0.8 shims ( over shimmed). This was an experiment, some time ago, to gauge the loss of lift as shim thickness is increased, so the data I have given is based on 0.8 mm shims .

In this configuration the spin up is very easy indeed, but with a higher sink rate power off ,and in turns, also the throttle setting is generally higher to maintain cruise and climb hence less flying time per charge.

The AJ 450 blades cut down will work well at much lower shim thickness and the model will fly "lighter" , as the thinner shims will give a similar effect to reducing the rotor loading , but the roll and pitch trim settings are likely to be different as the shims are reduced , and off course more time may be needed to get the rotors up to speed.

Tom.

[Stephen Jones]

Cheers Tom ,

I took the Auto G out today but as there was no wind and it was getting dark i decided to wait for a more suitable day .

I will let you know how i get .

Thanks once again for all you're help .

Cheers Steve ,