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Old Nov 19, 2012, 09:48 AM
Sky's not the limit, ground is
skydanz's Avatar
USA, CA, San Jose
Joined Dec 2007
855 Posts
Maybe it's a full moon or solar flares causing it.

Don
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Old Nov 19, 2012, 10:18 AM
Keep it simple
alfoot's Avatar
Salisbury,England
Joined Jan 2005
969 Posts
Paul,

Sorry to hear you are having problems with the Monotwirl.

Have you tried holding it into the wind with the motor running with the rotors up to speed (eg tilt the autogyro back about 45 degrees - I posted a movie way earlier in the thread) to feel if it wants to roll left? If so you might need to try pre-trimming some right rotor tilt.

Something else that could be the culprit is if the blades are glued too rigidly to the hub. I used UHU Por and the blades can flap quite freely. If you look at another movie I posted one of the blades was too free and fell off but even then it was still flyable. Rigid glue joints will tend to make it roll over.

Hope this helps,

Al
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Old Nov 19, 2012, 03:05 PM
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Paderborn DE
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Quote:
Originally Posted by skydanz View Post
Maybe it's a full moon or solar flares causing it.

Don
Makes far more sense than anything that I have come up with so far, did wonder why my fur grew that day. If she keeps winding me up like this I will be baying at the moon soon
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Old Nov 19, 2012, 03:31 PM
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Quote:
Originally Posted by alfoot View Post
Paul,

Sorry to hear you are having problems with the Monotwirl.

Have you tried holding it into the wind with the motor running with the rotors up to speed (eg tilt the autogyro back about 45 degrees - I posted a movie way earlier in the thread) to feel if it wants to roll left? If so you might need to try pre-trimming some right rotor tilt.

Something else that could be the culprit is if the blades are glued too rigidly to the hub. I used UHU Por and the blades can flap quite freely. If you look at another movie I posted one of the blades was too free and fell off but even then it was still flyable. Rigid glue joints will tend to make it roll over.

Hope this helps,

Al
Thanks for replying, help from the Master.

The model ‘felt’ OK spinning the blades up, no pulling either way and operating the aileron stick you could feel her tilting. As I launched it did feel right but to be honest it all happened so quickly on release that it is difficult to be sure.
On the first attempt I am not sure which way the model rolled but on the next 2 attempts she defiantly rolled to the right, so quickly that as she hit the ground (inverted) I had not had time to get on the right hand stick!! For the last attempt I had trimmed both aileron and rudder slightly left but she still rolled to the right.
Now for the confession, I used one of the new PU based glues to glue the rotor (against your advice, I know, sorry) as they are also quite flexible and when gluing the first head I used POR for the first 2 joints but is did not seem to have enough surface area to adhere properly. The next head will be constructed using POR, the U/C will be sorted, the fuselage stiffened and I am sure that a ROG take off will prove that your design is sound. I still think that the low weight and too much wind effectively caused my mishaps, but, MY BABY WILL FLY!!!!!

PS, did you design a twin rotor for RCM&E around 20 years ago???????? (Name rings a bell).
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Old Nov 28, 2012, 10:37 AM
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Success!! New head built and glued using only POR and a decent undercarriage fitted. Today was pretty much zero wind here Germany but misty so I went up to the field to try a ROG take-off to see if my Baby faired any better than with the last 2 disasters. Check all the controls, spin the blades by hand and gently opened the throttle holding full up to keep the tail down. She shot off like a scalded cat with the blades spinning to a blur within a couple of meters, I backed off the up-elevator and the tail rose on her own. As the blades didn’t seem to be getting any faster and the model was not accelerating anymore I squeezed in the tiniest amount of up-elevator and she rose majestically into the air!!!! Nose slightly up at full throttle and she was climbing nicely so I backed the throttle off and settled down into a flat wide circuit, yippee, she climbs, holds height and was nice and easy in the turns, not dropping her nose or ‘zooming’ (I was taking it gently). As she flew back in front of me I could see that she was vibrating really, really badly and she then began to loose power. I figured that the LiPo (old pack) was dropping out (it was also pretty cold) so I tried to bring her back around to where I was for a landing but unfortunately she just kind of dropped onto the ground quite hard. 1 Blade was broken (still holding at the leading edge where the flexible POR still held, sorry again Al for doubting) and I found the prop was about 10 meters behind where she had landed (must have come off in the air causing the ‘drop’). The flight was not long enough to trim her out and to really explore the flight envelope but it did prove that she fly’s and well at that. This has left me looking forward to enjoying some more Auto-Gyro fun and the next (twin rotor, aluminium tube rotor mounting booms) is in the planning stage and after that a self-designed 2 bladed pod and boom pusher is on the agenda.
Thanks for the design Al.
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Old Nov 29, 2012, 02:28 AM
Keep it simple
alfoot's Avatar
Salisbury,England
Joined Jan 2005
969 Posts
Paul,

I'm glad that you finally got it to fly. I hope that you will sort out the vibration problem (could it have beeen the propeller all along?) and give it another try. A movie would be good too.

In answer to your previous question it was not my design 20 years ago.

Al
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Old Nov 30, 2012, 01:07 PM
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OK, so gluing a blade back on was a bad idea, OK, so trying to fly when the wind had grounded the sparrows was also a bad idea, now I know, OK :-) ? Lost a blade at around 30 feet (the glued one) which, due to loads of POR sticking the leading edge in place did not fly off but kind of flapped around until it locked the head up. Once the blades top turning she doesn’t fly very well does she :-( ?
However, ROG take off, not vibrating as much and despite it being far too windy she was controllable until the blade dismounted so I am counting a success. Really annoying thing is that that was yesterday and today there was practically no wind!!! Oh well, build another rotor and try again.
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Last edited by PaulB; Nov 30, 2012 at 01:09 PM. Reason: Insert smileys.
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Old Jan 25, 2013, 09:43 AM
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Is 3-5 minutes flight a succsess? YES

Well, I crashed my Monotwirl again today but this time I am really happy about it!! The reason is that I crashed due to loosing orientation (over a foot of snow, low bright white cloud and the model in ‘virgin white’ depron colour), after flying my Baby for at least 3 if not 5 minutes!! Success at last, even if she did fly pretty badly.
To re-cap, I have trashed at least 6 rotor heads (may even be 10, lost count) due to everything going wrong that can do. C of G too far back, C of G too far forward, weak LiPos, un-balanced prop, defective aileron servo and a severe case of ‘bad luck’ (OK, most of it was home made ).
Anyway, having got over the shock of seeing her flying I started to try to get her trimmed out and to find the throttle sweet spot but she kept dropping her nose in every turn and rolling to knife edge even if I used the rudder to turn. This added to the fact that I could hardly see her half of the time as well as realising that my motor is marginal for this model lead to an interesting flight.
On the positive side, she tracked pretty well (even if I was holding up and left in most of the time as I couldn’t leave the sticks alone long enough to get to the trim), did not shake or vibrate, turned in both directions and climbed ‘acceptably’ at full throttle (anything less was making her drop her nose and roll). All this makes me pretty happy because now I can see that she will fly, and fly well with a few more tweaks.
Loosing orientation resulted in an arrival in a snow drift which cracked one blade and filled the motor with water so I stopped for today but before the next attempt she will be getting some colour and trim on the blades, may even be able to see her for most of the next flight
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Old Feb 26, 2013, 08:49 AM
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Sorted :-)

Just got back from a lunch time flight with my Monotwirl. The last flight has ended with a badly cracked fuselage (need to add throttle on landing) which peed me off because I had only just got her sorted and flying!! I had noticed that my tail was flapping around a bit in the air so I fitted a 6 mm cruciform crutch to bridge the crack and to stiffen her up, this has worked really well and she is now far more rigid for very little weight gain.

Cold, snow on the ground and a biting 3 – 5 MPH wind so I quickly fitted the battery and went for a stroll to spin the blades up. Climbed straight out level with no trim issues, flew for five and a half minutes with absolutely no problems and she looks really cute in the air (when I can see her, still virgin white Depron). Turns do need a bit of work to keep the nose up and she did 'dig in' a bit but quite flyable, interesting and enjoyable.

My Monotwirl is now sorted and flying really well, far better control and tracking than before now that the fuselage is stiffer so that probably added to my earlier problems.

Thanks again Al.
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Old Jul 16, 2013, 03:14 PM
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Paderborn DE
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And then good became perfect!!!!!!!

Just got back from a perfect evening flying my Twirl

I had neglected her a bit recently due to building a Crane Fly and a Spyro 111but had been playing around with different blades/ heads. I tried 3 bladed in 2 lengths with both carbon LE and wood, 4 bladed in 3 blade lengths with carbon rod or tube on the LE and have now got the perfect combination!!!!!!

Follow Al's instructions to the letter

I had broken a blade (4 blade carbon tube, and inch longer) and had got hold of 2 lengths of 3 mm pine so I knocked up and original head (even glued with UHU Por), threw it on and went off to the field. I did cut 2 LEs from each length of pine (you can get 3 out of 1 strip) whereas last time I had used 3 from one strip and 1 from another strip which lead to an imbalance and 1 blade being stiffer or more flexible.

Absolutely perfect, no trim needed at all (head at 90 degrees to the mast), turned exactly the same left or right, really really easy ROG take off in virtually no wind and I even managed a loop!!!

OK, I played around with Al's design and made a bit out of a pig out of her, but, it was fun experimenting and it may save you doing the same

Whilst flying I was thinking that I was lacking a touch of power, she flies fine at around 2/3 throttle but any more makes next to no difference, both my Crane and my Spyro have far more power so I figure that I need to fit a slightly bigger motor (I currently have a light 2 cell shocky one fitted). However, sitting here with a beer I think that I am going to leave her as she is, I will not be Hooliganing with a Depron model in high winds and she looks real good pottering around slowly on a nice calm summers evening like tonight.

(Very happy).
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Old Aug 03, 2013, 08:24 AM
jclassic1
New Houghton, Derbyshire, UK
Joined May 2006
1,382 Posts
Looking around on the auto gyro site I noticed that Tom Wrights Crane fly lite uses a Y lead to couple the rotor roll and rudder together.Has anyone tried this on the Mono Twirl or the reason for doing so.
My last experience with the Mono Twirl was a disaster as I just could not get it to fly at all.This was down to me not knowing what I was doing more than a fault with the model so this time I am following the plan exactly and hope for better luck with my maiden.
I have made a rotor using 6mm depron for the blades but reading the above posts from Paul it seems that I need to use the 3mm as stated and Uhu Por glue.

Hope to have it built soon and then on to the Crane fly lite.

John
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Old Aug 03, 2013, 11:14 AM
Keep it simple
alfoot's Avatar
Salisbury,England
Joined Jan 2005
969 Posts
John,

Good luck with your Monotwirl.

Please use UHU Por for building the rotor, it is the flexibility of the glue that allows the blades to flap. And also I would recommend 3mm depron for the blades.

On coupling aileron and rudder I have always found occasions where I have needed "crossed" controls when flying autogyros eg when turning initially, rotor tilt and rudder in the direction of the turn but, once the turn is entered sometimes you will need to keep the rudder in the direction of turn but apply rotor tilt opposite to the turn to prevent the autogyro from over-banking. it is not unlike flying a high aspect ratio glider in that regard.

Hope this helps, please let us know how you get on.

Cheers,

Al
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Old Aug 04, 2013, 12:32 AM
jclassic1
New Houghton, Derbyshire, UK
Joined May 2006
1,382 Posts
Hi Al,thanks for the reply and advice,I am waiting for my 3mm depron to arrive so I can build the rotor as you designed it.On my last Mono I did not fit any landing gear and was wondering if that may have made the model a bit top heavy which increased the roll over tendency .I found and old set of landing gear in my spares box which seems to fit OK so will give it a try.
This is my Mono so far I just hope the addition of landing gear has not added to much extra weight.

John
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Old Aug 06, 2013, 01:33 AM
jclassic1
New Houghton, Derbyshire, UK
Joined May 2006
1,382 Posts
To help with any excess weight I thought I would add a wing.I must admit that I quite like the look of it ,a bit like the very early gyro planes.
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Old Aug 06, 2013, 02:49 AM
Keep it simple
alfoot's Avatar
Salisbury,England
Joined Jan 2005
969 Posts
John,

Looks good.

I did a MicroMonotwirl like that a few years ago - 12 grams with magnetic actuators for rudder/elevator. Details in the big Twirl thread, movies on my youtube channel.

It flew OK without any control on the rotor.

Al
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