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Old Dec 15, 2008, 05:07 PM
It was a GLITCH! Honestly!
SafeLandings's Avatar
Stourport on Severn ,Worcestershire, United Kingdom
Joined Dec 2007
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Build Log
My RC Pusher Autogyro designs

Well my PT25 is basically finished and I just cant afford to press on with my Large DAG right now.
I needed a new project to keep my mind active during these cold winters evenings and I have been really impressed with Peter O's latest creation so I thought I would have a go at my own pusher gyro.
I cant buy any materials at the moment so I have had to use what I have in my workshop which is basically balsa and ply. I have DAG blades, an electric motor,esc and batteries so it has been roughly designed around these. My thoughts are if I can build a pusher with an AUW lighter than my R2 then there is no reason why it shouldnt fly??
The only trouble is I have never built, flown or even seen a pusher autogyro fly so I am totally in the dark with this subject.
I know there are experts out there so I am calling on you guys to point me in the right direction if you wouldnt mind please
Things like thrust lines, hang angles, mast heights,motor heights etc, etc,etc

Heres a few photos of what I have done in a few evenings..if you see that I have gone about something the wrong way please tell me I wont be offended.
Your thoughts and ideas will be greatly appreciated.

Regards Rich

PS thanks for the photo Peter
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Old Dec 15, 2008, 10:29 PM
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Bedford Indiana
Joined May 2004
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Rich. I don't know squat about pusher gyros but what you have done looks very, very nice. I have only heard they are more difficult to fly as an RC. I did build the EXP kit offered by Hippo but never got to maiden it so I don't know how it would have done. Good luck on your project. I will be watching here for progress. Merry Christmas.

Chuck
...somewhere in Indiana...
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Old Dec 16, 2008, 02:03 AM
Ozzie GyroNut
Hervey Bay, Australia
Joined Mar 2007
138 Posts
Hi There,

Download Mickey's BeGi plans at http://www.mickeynowell.com/sitebuil...i_12_18_07.pdf

Use his angles of thrust, balance, and so on. This will help you to get yours going.

Regards,

Francois
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Old Dec 16, 2008, 05:12 AM
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Quote:
Originally Posted by HobbyCAD
Hi There,

Download Mickey's BeGi plans at http://www.mickeynowell.com/sitebuil...i_12_18_07.pdf

Use his angles of thrust, balance, and so on. This will help you to get yours going.

Regards,

Francois
Bearing in mind Rich is using his spare DAG blades I would suggest starting from some of Jochen's 3 bladed designs rather than one of Mickey's a 2 bladed design. I know Jochen has experience of using both 2 and 3 bladed heads on similar airframes and there are differencies.

When asked about 2 vs 3 bladed Minimums Jochen said "flying the three-bladed Minimum is fun, flying the two-bladed version is hard work."

PeterO_UK
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Old Dec 16, 2008, 05:14 AM
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WOW Rich, it's look like it is already almost ready to fly

It's nice to know I've inspired someone to do something, but Jochen deserves the real credit.

Watching with interest,
PeterO_UK
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Old Dec 16, 2008, 05:20 AM
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Quote:
Originally Posted by PeterO_UK

When asked about 2 vs 3 bladed Minimums Jochen said "flying the three-bladed Minimum is fun, flying the two-bladed version is hard work."

PeterO_UK
Just to be clear, this statement applies to tilting spindle type heads. BEGi uses a swashplate and flybar and is quite stable compared to a two bladed TS head.
Francois' suggestion about thrust angles, etc are still valid.
Comparing TS to swashplate heads is comparing apples to oranges.
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Old Dec 16, 2008, 05:27 AM
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Quote:
Originally Posted by mnowell129
Just to be clear, this statement applies to tilting spindle type heads. BEGi uses a swashplate and flybar and is quite stable compared to a two bladed TS head.
Francois' suggestion about thrust angles, etc are still valid.
Comparing TS to swashplate heads is comparing apples to oranges.
Indeed, I was probably thinking more of the fact Rich will be using a TS head rather than a swashplate when I suggested starting from Jochen's designs would be more appropriate than starting from your designs.
PeterO_UK
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Old Dec 16, 2008, 05:34 AM
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DeRidder LA.
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Rich,
That is looking good man! Mickey speaks the truth brother. 2-blade teetering can be done, but the amount of work required to fly it will most likely ruin the fun. A true Teetering two blade is like the holy grail of R/C autogyros. If you must have two blade you should definately go with the setup that Mickey designed and uses. I would just go for the three blade with the flex-plate head myself(primarily because I'm lazy). Keep up the posts, she's looking the part for sure!
Regards,
-Mike
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Old Dec 16, 2008, 07:20 AM
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Rich,

you seem to be aiming at something like the DAG R2 in size and weight. Why don't you start off with a DAG R2 head, keeping all the angles and control throws and whatnots?

The thrust line of your motor shuld be parallel to the 'axis' of your fuse, and you should make the motor position adjustable vertically and to the right of the gyro. On a pusher the distance between the motor and the c.g. is very small, and it's far more efeective to offset the motor then to tilt it. I can explain that in detail, if you want to, but that's a post of its own. You probaly have to offset the motor to the right, to compensate the prop wash effects on the tail unit. If you don't know this video
http://www.rcgroups.com/forums/showt...93#post7087583
have a look at it.

The horizontal position of the c.g. should be before the thrust line of the rotor, otherwise the gyro will become unstable around the vertical axis. If you are using full head control - the two servos indicate that - the c.g. should be before the thrust line, even if you are pulling up elevator.

I'd put the motor position about a centimeter or so above the c.g. for starters. If your gyro has a tendency to climb too steep, move the motor up a bit.

The tail unit should have a minimum of 3 to 5 cm clearance to the prop. If your c.g. is too far out front, you can move it further back without problems.

That's the basic advise I can give you at the moment. It would be nice, if you posted some more details concerning dimensions and weight and so on.

Jochen
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Old Dec 16, 2008, 08:10 AM
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Jochen,

When Rich asked me about CofG on my Minimum I produced the attached picture. I suspended the model from the top of the mast, and from the two collets at either end of the 8mm tube.

I think its CofG is in about the right place ?

PeterO_UK
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Old Dec 16, 2008, 08:47 AM
It was a GLITCH! Honestly!
SafeLandings's Avatar
Stourport on Severn ,Worcestershire, United Kingdom
Joined Dec 2007
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Wow gents ..thanks for all the info links and videos etc lots of information for me to look through.
So to get the CG position I really need to build the boom and tail feathers, from this I can start to determin the CG posion and thus the motor height etc
For now I will stick with the 3 blade head as I have one to hand, as for the teetering 2 blade head or the swash plate type..that would be nice but I dont think I have the skill to build or fly such a gyro at this moment in time.
I will post some photos later on with some dimensions and weights..the rotor span will be around 50" for now..if once the gyro is built and they dont look look correct I will alter them to suit...kind of 'suck it and see'. will also be load sharing type head like alot of others!
Thanks again chaps

Regards Rich
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Old Dec 16, 2008, 09:57 AM
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Peter,

yes, looks alright.

Jochen
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Old Dec 16, 2008, 03:59 PM
It was a GLITCH! Honestly!
SafeLandings's Avatar
Stourport on Severn ,Worcestershire, United Kingdom
Joined Dec 2007
4,806 Posts
I managed to get a little done today, I have boxed in the mast, started on the load share head, made an alloy UC up and started the boom.
I am unsure as to whether i should make it a tail dragger or tricycle UC?? could anyone suggest the best option or is it personnel tastes?
I have also noticed on most pushers that the fins are quite large, does this have to be in the propeller wash to help things?

So a few dimensions etc
Mast tilt back is around 8 degress and from the base of the fuz to the top of the spindle mounting plate is 470mm. From the centre line of the mast to the nose is 370mm and the boom has been made longer than needed as Im not sure on its final length??
Its weight as you see it with one servo mounted ,uc and alloy rotor spindle is 500g..which I think is a touch on the heavy side.
Regards Rich
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Old Dec 17, 2008, 03:26 AM
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Rich,

as the motor position of a pusher is higher than that of a tractor, it's better to use a tricycle configuration. You don't have to worry about the gyro toppling over.

My Minimum and Nanomum have the horizontal stab more or less directly in the prop wash, on the Micromum the position is very much lower. All of them fly. Just build something that looks sensible to you.

You haven't mentioned your rotor diameter yet, so it's hard to tell about the weight of your gyro.

Jochen
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Old Dec 17, 2008, 09:48 AM
It was a GLITCH! Honestly!
SafeLandings's Avatar
Stourport on Severn ,Worcestershire, United Kingdom
Joined Dec 2007
4,806 Posts
Jochen,
Sorry..I forgot to mention the most important thing! ..the blades I have to hand have a 50" rotor disc diameter, I have got some longer blades I could use which would give me a diameter of aroung 58"...the smaller ones are covered and ready for use.
Thanks for the info on the tailplane, I will go down my shed and start shaping some balsa sheet..I will post some photos later.

Regards Rich
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