Panther Trainer Autogyro

[Terry Whiting 1]

Rich,

Is there a workable formula to find the balance point of an Autogyro as we have with our fixed wing models. For the maiden flight of my own designed fixed wing models my starting point is at 25% chord or 25% ADMC for a tapered.wing.

Terry

[Richard Harris]

Terry,

I have never seen a formula, the reason being I would think is that there are too many variables. The best possible thing we can do is to get the CG forwards of the rotor spindle, normally done by hanging the model from spindle. But in the Panthers case I have used a CG point as I thought potential builders would feel more at home than the hard to measure hang angle.

A nose heavy autogyro will fly, a tail heavy autogyro will fly but not for long! A sure way to know that the CG is in a favourable position is to chop the throttle at height and take your thumbs off the controls. If it is on the money it will descend forwards, if it is does a spiral then weather cocks into wind duplicating this all the way down then weight must be added infront of the CG. This effect is more evidant with pusher type models as the moment arm is shorter and the fuselage blocks airflow over the vertical fin. You will see modern autogyros have fins towards the outside of the tailplane to compensate this, just like I did with the Fire Fly.

Rich

[Terry Whiting 1]

Rich

Thank you, I wondered if it might have been calculated in degrees forward of and imaginary line through the shaft, but I can see now how dedicated you must have been over the years, and for the French to honour you for your endeavour says it all......you certainly earnt it pal

Regards Terry

Edited By Terry Whiting 1 on 19/02/2013 21:02:13

[Richard Harris]

Terry,

As a rule for a 3 bladed head 4-7 degrees tilt back is about average for level flight. However, different types of head/ negative shim/blade design/AUW etc can all alter this tilt back for level flight. Because of this it is hard to determine even an angle like you have suggested.

The French award was a little embarrasing at the time

Rich

[Big T]

My Panther head.

 

Edited By Pete B - Moderator on 20/02/2013 00:31:55

[Richard Harris]

NDJT,

Very nice work , is that the rudder servo mounted in the side of the fuslelage at the rear keeping it simple?

Of course, we do expect a flight video aswell !!

Rich

[Malcolm - coolwind.co.uk]

Rich,

I'd like to get my control rods cut to length. I guess for Roll control this is quite easy as the head will have a neutral tilt of 2-3 dgrees which will determine the length.

On Pitch, I think I need to know the neutral angle of the head - is this as shown in the plan, ie is it drawn in the flying configuration or not?

Thanks

Malcolm

[Richard Harris]

Malcolm,

This all comes in part 2 and to make life easier for builders ( rather than stating angles and confusing folk) I have a measurement from the top of the fuselage to the centre point of the pitch bolt.

But as you have flown before and will most likely be the first to get one in the air from the mag build a good starting off point is 4 degrees tilt back. If the rod is threaded top and bOttom this will give plenty for fine adjustments when ready to trim.

 

Rich

Edited By Richard Harris on 20/02/2013 16:46:44

[Erfolg]

Richard, will part 2 indicate how to practically measure this angle.

I always wonder what an angle is being measured against. I suppose it is the tail plane in this instance.

I am also hoping the explanation of the negative angle, that is referenced from time to time is relative to.

[Big T]

Posted by Richard Harris on 20/02/2013 09:52:30:

NDJT,

Very nice work , is that the rudder servo mounted in the side of the fuslelage at the rear keeping it simple?

Of course, we do expect a flight video aswell !!

Rich

Yes i stuck the rudder servo into the side of the fuselage. Simple and more direct, I rhought. I am trying to get a video together.

Tim

ps have you seen the Gemini build thread?

[Big T]

Posted by Malcolm on 20/02/2013 15:02:12:

On Pitch, I think I need to know the neutral angle of the head - is this as shown in the plan, ie is it drawn in the flying configuration or not?

Malc, I just set mine to the measurement from the top of the hatch to the ce tre of the ball joint bolt..

T

[Richard Harris]

Tim,

I would be interested to know, was this measurement close and did you add any pitch trim?

 

Rich

Edited By Richard Harris on 20/02/2013 21:07:14

[Pete B]

The gearboxes I mentioned earlier in the thread arrrived today. They are very different in size - the frame of the smaller is about 30x35x17 and that of the larger 40x45x20.

The interesting thing is the mainshaft on both is 4mm and the propshaft 6mm, so apart from the size of the mounting frame, the working parts are identical. I'll be using the larger one as it just seems more appropriate for the job it has to do:

Pete

[Andy Nash]

Getting the correct angle.

The measurement from the top deck (where the CofG is marked) to the pitch control screw is 208mm.

 

I hope this helps

Regards

  Andy

Edited By Andy Nash on 20/02/2013 21:45:26

[Malcolm - coolwind.co.uk]

Rich, Andy

Thank you

The 208mm measurement looks an easier way to set the head angle than trying to measure the actual angle.

The 208mm (there abouts) also seems to agree with the setup as drawn on the plan, However the angle on the plan measures at around 7 degrees.

If the measurement was the result of flight tests then it's probably a better guide to go by, as angle are notoriously difficult to measure,

Malcolm

[Big T]

Posted by Richard Harris on 20/02/2013 21:06:59:

Tim,

I would be interested to know, was this measurement close and did you add any pitch trim?

Rich

Edited By Richard Harris on 20/02/2013 21:07:14

Rich, the measurement was bang on for me, with a standard 4s 3000 lipo, I dont remember any great issues with pitch on the first few hops or flight, just roll and rudder trim , as usual.

With a 4s 3000 Tipple Charge lipo I needed a bit of back trim, and of course when it is windy or calm there are trim changes. With the same motor as my RPG I hardly ever fly on more than 50% throttle and I am getting 8 to 10 mins flight times in warmer weather. If I slacken the head pivot blt off to give a bit of side play I can get an interesting side slip going! I would advise everyone not to play around with the undercarriage height or width. Set is up as the plan and it ill almost take off hands free (providing the head is up to speed) and give excellent landing speeds.. It helps to have a god pilot in the office, The Stig is the one for me!

Tim

PS the first time I did the pitch lincage rod I took the measurement ffrom the top of the fuselage not the top of the deck! That really looked interesting!

[Andy Nash]

i am pleased the dimension helps.
If you want I could measure the roll for right/neutral/left? If you think it would help?

Regards
Andy

[Andy Nash]

The pitch angle is not too important. If two identical Panthers were flying together and the pitch angle was the only difference the one with a greater angle would fly slower. To reduce forward speed well pull back on the head. To climb we increase engine power so as to get rotor speed increase and this will give us lift.

Hope this helps chaps.

Andy

Edited By Andy Nash on 21/02/2013 20:34:23

[Richard Harris]

Andy,

I am sure all this info will help most builders, thankyou

 

Pete,

The shafts on those gearboxes being both the same diameter is a bit naughty and not what I would expect to recieve. But I am sure they are more than up to the job.

 

You will just have too build something else after!

 

Rich

Edited By Richard Harris on 21/02/2013 22:14:22

[flyby]

Love the panther, just got to build it, you state that the centre of the mast is 6mm hard balsa, but if you go to page 69 ( march issue ) it states it as 6mm ply, which is it, so i can get on with my build

thanks geoff

[Pete B]

Whoops, a typo on the cut-away drawing! Well spotted, flyby, and welcome to the forum!

I can confirm that the mast centre is of 6mm hard balsa, as per the text and plan

I take it you'll be posting a blog of your build, as I and a few others are doing?....

Pete

[Richard Harris]

Hi Geoff,

Welcome to the madness, looking forward to your build. Any questions just fire away

Rich

[Bass]

Richard

This is my first post on this site (my first post on any site for that matter!) I'm very interested in the Panther and I must congratulate you on the design, finish and, particularly, the speed of construction. I seem to remember that Biggles had some contact with an autogyro - which dates me! Anyway I'm hooked on the various videos on this thread and would like to have a go at building one.

I'm happy with all the wood, glue and nuts & bolts aspects but there are a few points I'm not confident about, although I keep picking up tips from other posters on this thread.

Before I start to cut wood I would be grateful if you could clarify the following points:

1) On 13/7/11 you show the main servos positioned at 90 degs to each other, unlike on the plan?

2) You refer to servo types on 25/7/11 and 27/7/11. I'm not familiar with Tower Pro and have found some some worrying reports about clones on the internet. Can you suggest any other servo types that might be OK? I've not had much need of high torque servos on my previous fixed wing models.

3) The ball joints / push rods look very substantial on the head, but is that a 'special' servo arm on pic of 13/7/11? I'm not into threaded welding rods not having any taps and dies. I was thinking of standard threaded push rods inside an alloy tube filled with epoxy to stiffen it up?

4) Finally (for the moment!) where do you get your 1.5 mm glass fibre sheet from?

Sorry to ramble on but I would feel a lot more confident to continue if I could settle the above.

Regards

Barry

[ALAN HALFORD]

Richard

A friend and myself are going to build your Panther Autogyro but are a little puzzled by discrepancies between plan build article and sectioned drawing in magazine (March 2013 issue) - i.e.: mast on plan is indicated as being built from 3mm/ 6mm balsa but sectioned drawing shows lamination of 3mm balsa and 6mm ply - as this is obviously a part that takes some load which is correct?

Also Mast top tongue on plan states light ply but build article emphasises that this part should be birch ply - which is correct?

You have used Towerpro 996 MG servos in your build but opinions on the internet suggests problems with these i.e. quality, overshoot etc. Have you experienced any of these snags also do you find them reliable and long lasting?

Really great to see somebody venturing into a different field of modeling and we are really looking forward to building and flying our Panthers.

Many thanks Alan

[Andy Nash]

Hi Barry and Alan

Welcome. Ramble as much as you like.

Rich hope you don't mind me answering.

I have used the MG995 servos and the now the MG996 servos. The MG996 has a better gearbox and I have found them to be smoother. However some suppliers are sending the plastic arms that come from standard servo!! Look closer at the advert you need the more substantial arms. Best thing is to use aluminium arms from Ebay when using the MG995 or MG996 servo.

Regarding the servo locations for the head. The plan is correct but the front servo needs to be 5mm lower, to allow for the servo mounting screws.

Alan the mast is hard balsa not ply.

GF or Glass Fibre sheet supplier....

MacGregor Industries Ltd. Cordwallis Street. Maidenhead. SL6 7GF Telephone 01628 760431 email [email protected]

Part No. MAC4250 Epoxy Glass 304 x 152 x 1.6mm approx £5.95

web site = http://www.macgregor.co.uk/macgregor/epoxy.htm

Regards

Andy

Edited By Andy Nash on 24/02/2013 16:25:11