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Old Dec 23, 2004, 03:07 PM
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Terry S's Avatar
Bridgwater, UK
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Can these things LIFT ?

Hi all, Im new to auto gyros and I was wondering if an electric AG would be able to lift a camera for aerial photography. If so I have a payload of 0.5Kg that would need to be lifted and still handle ok. What sort of size would I need ?

Thanks, Terry
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Old Dec 24, 2004, 12:17 AM
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JWarren's Avatar
Port Saint Lucie, Florida, United States
Joined Aug 2004
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I am not trying to sway you from doing AP with a gyro. But why don't you just use a plane?

Just curious.

You would need a gyro that was built very light for it's rotor span then factor in the camera to see if you would be able to get off the ground so to speak. I am not really sure which model would do the trick. Maybe one of the other fellas around here can help you with that.

John
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Old Dec 24, 2004, 06:37 AM
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Bridgwater, UK
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Hi John, I do use a plane but it dose need a bit of room to land, I just thought an autogyro may be the thing to give me good stol performance ?
If Im wrong thats fine and I will go back to practicing my heli flying, thanks for your reply.

Terry
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Old Dec 24, 2004, 07:37 AM
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Autogyros have in general a long takeoff and a short landing, maybe not the thing for aerial photography. Also the lift to drag is awful and you need lots of power just to fly and endurance is limited. You might make something with
pre-spin to get the takeoff shorter and have lots of power to overcome the weight of the camera, however you then have something as complicated as a heli. If you don't mind the money there is a stabilized platform for sale at
http://www.rctoys.com/draganflyerxpro.php, it can carry one pound.
It is ready to fly but pricey ($5000!).

There are lots of aerial heli cams but this takes helicopter skill to master, but once mastered you can pretty do anything. A pound of payload is not
a problem for a .60 gas heli, but then noise and exhaust are an issue.
Most commercial platforms use larger gas engines.

I would bet that the best camera platform of all would be a powered parachute, one of those things with an oversized parafoil parachute with
a motor on back. They are short takeoff and landing and fly very slowly.
Also with the motor off (if electric) you would have absolutely zero vibration.
With gyro/heli platforms vibration is always an issue.
Don't know about the payload capabilty, but it seems with a slight airspeed increase you could lift quite a lot.
mickey
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Old Dec 24, 2004, 08:39 AM
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Bridgwater, UK
Joined May 2003
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I was thinking I could pre spin the head then hand launch, then when landing have a very steep approach and land slow. I have a Vario Benzine heli but it is noisy and I have only just got the hang of the basics. I was reading the an autogyro was very stable and I thought this would take some workload off me while taking the shots. I did have a go at a large powered parachute but it was a pig to launch in anything but flat calm days or it would wrap it self in knots on the ground before I even got it in the air. Even then the climb rate was poor so you needed a lot of room for take off but landing was easy. In short Im looking for something with good climb out and steep appoach and also very stable, duration is not number 1 for this job, I have a plane for that. Any ideas ?

Terry
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Old Dec 26, 2004, 01:58 PM
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One thing that impressed me about my Robbe/Schluter Whopper was how easy it was to fly. While I seem to manage helicopter flight pretty good, I've never taken the time to really be good at it. Consequently I always felt I wasn't in complete control. Now here's the Whopper with a complete helicopter head that breathes stability. Flying the Whopper gave me the confidence to complete my first full down helicopter autorotation.

I think a properly sized electric Autogyro to carry a particular camera system would make a great platform. With a good breeze you'd have the ability to hover which might be very useful for stationary shots.
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Old Dec 26, 2004, 04:46 PM
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Bridgwater, UK
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Ahh...Now thats good to hear, I was begining to think I had got autogyros all wrong. Now all I need is one of you gyro boys to give me some figures as a starting point ???
Remember I need to lift 0.5Kg max ! I am keen to use a heli head and was wondering if broarder or larger blades would be needed or better than the originals that were used for a heli of the same weight ?

Thanks, Terry
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Old Dec 27, 2004, 08:00 AM
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My rule of thumb is that the disk loading needs to be
5 ounces / square foot / #blades, i.e. 2 Bladed design
needs to be < 2.5 ounces/square feet of disk area.
You also need about 100 watts/pound aircraft.
With a .5 (1.1lb) kilo payload, I'd estimate that you
want your payload to < 25% of the aircraft weight.
This turns into a 3 lb (1.4 kg)aircraft empty, 4.1 lb (1.9kg)gross.
At 64 ounces, with two blades @ 2.5 ounces/ft^2
the rotor radius is 2.9 (880 mm)feet.
Rotor diameter is then about 6 feet (1.82 meters).
You'd need about 600 watts brushless, 900 brushed electric
power plant.
If you chose a Kontronik 600 with gear drive, for example, this is about
300g, 3 Apogee 4160 3s1p lithiums would give about 30 volts at
275 g apiece, Thus the powerplant weight is ~1.2kg.
Carbon fiber 800mm heli blades weigh around 200-250 g each,
that's another .5 kg.
Weight is up to 1.7kg, empty with no airframe, this is higher than the first guess,So re-estimating, Same powerplant 1.2kg,
guess at .5kg airframe weight, .5 kg blades.
Total 2.2 kg, .5 payload, total 2.7 kg gross.
About 6 pounds, = 600 watts minimum needed for agressive close quarters flight and climbing.
Keeping the disk loading the same = rotor radius 3.5 feet = 1 meter
radius, 2 meter diameter. I might start with off the shelf 800mm
heli blades with no payload to see what it flies like.
This is probably do-able. Perhaps start with .40 sized helicopter
mechanics including main gear, and autorotation clutch, in case you want
to try pre-spin later. However, I've found
that you can taxi back and forth and get the rotor speed up with
no need for pre-spin gear. I fly from the street at my house. You can go watch the videos at www.mickeynowell.com/id9.html to get and idea of what kind of residential environment you can operate from. If you left the collective pitch mechanism in place that would make spin up easy by taxing at low pitch, then pop to flight pitch just before accelerating to takeoff speed.
I would not try to do direct control with a rotor that size, the servo
loads would be large, and you are probably more interested in reliability
than scale looks.
You might have to make your own blades, but that is fairly straight forward.

This should be feasible (sic), you'd have to be careful with the airframe design
to keep it down to .5 kg (including radio) but this should be possible.

I will be very interested in seeing this project come to conclusion myself.

Good luck.
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Old Dec 27, 2004, 08:13 AM
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Bridgwater, UK
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THANKS for the great info, that tells me what Im in for if I go ahead with this, just what I was looking for. Im still at the stage of bouncing ideas at the moment but I do have a Kontronik FUN 600-18 with gearbox and a Beat 50-8-30 sitting on the shelf doing nothing so I would like to use them if I can. I have seen your videos and found your simple desigh very inspiring.The other thing I was interested in is the possable advantages of using contra rotating rotors, do you have any comments on this ?

Thanks Again, Terry
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Old Dec 27, 2004, 01:54 PM
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Bridgwater, UK
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Oh, I forgot to ask, do you think a pre spin and hand launch is possable as I need to fly out of rough fields sometimes ?

Terry
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Old Dec 27, 2004, 02:47 PM
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Tough question on the size you are talking about, hand lauch of a two meter
6 pound aircraft might be entertaining. Can I watch ? I'd consider a mechanical pre-spin
of some type, maybe an electric starter sticking in the bottom that drops away. Perhaps a little trailer with a launch ramp that includes a prespin
motor with wheel locks, then you spin up, drop the pre-spin motor away
then release the chocks and add power and fly off.
If I built this I'd probably just use it all the time. If you started with
heli mechanics you could just drive the main gear from the bottom. Of course if you use collective you could pre-spin with some negative pitch on the pre-spin platform, dump positive and fly off vertically while adding power to start moving, then you'd have true VTO and short landing capability.
There are lots of options here.
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Old Dec 27, 2004, 03:46 PM
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Terry S's Avatar
Bridgwater, UK
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Hmmm, yes the hand launch idea dose scare the hell out of me but if it works ok....
If it is possable to pre spin with enough enegy to go VTO then transition to normal flight then that is a much safer bet. Thinking about it my boy has a toy just like it, he pulls the string and the toy heli/rotor leaps into the air,the only question is would I be able to transition before the enegy ran out ? Its starting to look possable, remind me again, can autogyros fly hands free, are they as stable as planes ?

Terry
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Old Dec 27, 2004, 04:58 PM
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If you are doing this as a business I'd invest in either the fma autopilot or the
ikarus three axis gyro. I assume that you are trying to do business not be a hero.
For that matter the fma autopilot with a heading hold tail rotor gyro would
make your average helicopter hands off stable just as well, I'd do that before I went to the trouble to build a pre-spin capable vto gyrocopter. The only complexity you are saving is the tail rotor control and with a good heading hold gyro that is a non issue anyway.

The simple approach is to get a helicopter and an fma autopilot and a very good heading hold gyro. Buy some long flat bottom blades, go down a tooth or two on the pinion gear to turn the big blades and your are in business.
A gas xcell or similar will do this job all day long and with the fma and heading
hold it will take not a whole lot of skill to fly. Then you get true VTOL, heavy lift, runs on car gas, fly anywhere capability. A big advantage over the gyrocopter will be the ability to point the nose somewhere other than into the wind, this should be a big advantage to photography.
With the autopilot and heading hold all you'd have to do is correct position drift with the wind, the gyro would hold the nose on station, the autopilot would keep you level. How much easier could it get....
Heck, You come up with the gear and I'll set this platform up for you RTF for a small fee....
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Old Dec 27, 2004, 05:36 PM
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Bridgwater, UK
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Yes it is a close call and the heli may still win but I always like to explore every ally way. I do have a Vario Benzine heli which is very good but it is noisy and hard to hold stable at long range while taking pictures (I cant do it !) where a plane is easy but needs lots of space to land. The answer may be to invest in some autopilot gear to hold it for me, ive been looking at the carvec system. I surpose an autogyro just looks like a midway machine to me, a third choice, not to replace the long range plane or the hovering heli.
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Old Dec 27, 2004, 06:42 PM
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I fly both heli and gyro, in forward flight I find the stability identical, they are both rotor craft. All rotor craft are longitudally unstable so they are going to
behave the same way at distance. There's no such thing as a trimmed, hands off rotorcraft, something called negative airspeed stability takes over, also there is not such equivalent to dihedral in a rotorcraft. The pilot is in the loop all the time. A free flight rotorcraft is possible by making the instability time constant long enough that it lands before it goes unstable, but eventually all rotor craft need flight correction.
The autopilot idea in your heli increasingly sounds like a good idea....
The gyrocopter at far distance will be almost as busy to control at distance as the heli...
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