Ag Gyro - How to do it?


Staff member
Looking at Stan's pictures of farm country got me thinking about gyros and farming again. My parents didn't farm, but I grew up in a very small farm town and worked on farms from the time I was 12 until after I graduated from college.

I've spent quite a bit of time thinking about what would make a good gyro setup for spraying. I'm pretty sure I'm not the only one that has tossed this concept around.

How about joining me for a little brainstorming on what would be necessary to build a good, safe, reliable machine for spraying.

To build something commercially takes incredible amounts of time and money, so lets limit this discussion to building something experimental. Now as I understand it, this could only be used by a farmer for his own crops, or possibly owned by a small co-op of farmers for use on their farms. Does anyone know the limitations regarding the FAR's and using an experimental aircraft for spray work?

Next, I've considered the machine. I've thought why not use a sparrowhawk and just replace the passenger seat with a tank? But then I thought for something dedicated to spraying, you would be better off with the pilot centered and the spray tank behind the pilot, just forward of the mast. Maybe a Dominator or Air Command Tandem arrangement with the rear seat replaced by a tank. However you'll need some type of enclosure to protect your pilot from chemicals.

Now, for lifting capacity, what is the largest rotor system made for a gyro? How much water/chemical mixture could we carry? Also, does anyone know how many gallons per acre the planes apply? I used to spray with a spray coupe which normally put down 10 gal. per acre, but I think I remember planes used about 5 gal. / acre or less. At 5 gal / acre, if you're able to carry a payload of 400 lbs. or 50 gal, this only allows you to spray 10 acres a trip, thats an awful lot of reloading. I'm thinking that 5 gal/acre might be high, help anyone?

There could be some tremendous benefits to using a gyro. Spray Planes use alot of time and fuel shuttling back and forth to the airport but a gyro would only need 300-500 feet of decent road to land and take off. Loading could be done using a portable tank truck rather than a fixed base like the spray planes. Also, because of the increased maneuverability and the ability to slow down considerably more than airplanes, the accuracy of application should be much better.

There are many things to consider for such a project and I've only touched on them here. I know that others have thought about this while daydreaming, what are your ideas?
Todd: They are getting the chemicals down to very minute amounts per acre...something like 2 gallons chemicals/water per acre.

Raf makes a spray has the side tanks and a little boom. I have read about their ag version..but thats as far as I am going in that direction.

I would not see the practicality of it as you would need a runway to take off loaded and to be there you are stuck to an airport.

The GPS guided spray planes are out of this world anymore. They can load up and spray several farms at the same time. The GPS is constantly monitoring ground speed and adjusting spray volume accordingly. There are GPS maps of each farm loaded and you will see the spray momentarily shut off as it crosses a little waterway..or ditch. THis no longer has to be done by the pilot.

Also...the spray pilot has a screen that literally paints over where the field has been sprayed. The pilot can make a pass....and then make another pass spraying a neighboring field. These different accounts are all being electronically painted until the field is done. If the pilot gets rained problem...the computer lets him start exactly where he left off.

He has heads up displays showing that he is on the flight path,,,or left or right of it. Sure a lot different than the two guys standing in the end rows with flags showing the pilot where to spray. or...the tissue paper dispenser that blew out squares of tissue paper leaving a litter trail in the crops....

Most of a spray planes time is spent making the turns and the GPS just helps coordinate different accounts minimize a lot of turning.

They can spray sidwways across a field as the spray will automatically shut off when the plane reaches a "painted" area in the computer.

It is serious business getting down and low to the the heat...loaded heavy....big mistake....and :eek:


brett s

Gold Supporter
The amount of product per acre depends a lot on what type of crop - back when I was doing ag work in helicopters we used anywhere from 2-10 gallons/acre. No high-tech stuff for use, no GPS or anything like that (being restricted category, most helicopters didn't even have a compass - airspeed & maybe an altimeter, plus engine instruments). Your turnaround is quick enough that you can see the spray still settling from your last swath run, no big deal.

With helicopters the advantage we has was loading onsite, carrying 60-80 gallons a trip (in Bell 47's & Hiller 12E's) you were landing every few minutes to fill up again. Using a tank rig on a truck we could refill in less than two minutes, not a big deal...

The airplane guys could always do it cheaper because of the higher helicopter operating costs, we ended up with jobs that they just couldn't do - smaller fields, or ones that were full of wires or other obstructions. I always hated flying under wires...

The runway requirements of a gyro working at max weight (and usually in hot weather) will probably mean you're working off an airport just like the airplanes, but with far less capacity & much slower ferry speed as well. Unless you've got a runway at your farm, the economics won't work out. On the helicopter side, if it was more than 50 miles we trailered it to the site - and you wouldn't even fly that far unless you had 150+ acres to do.


Hi ToddP;
There could be some tremendous benefits to using a gyro. Spray Planes use alot of time and fuel shuttling back and forth to the airport but a gyro would only need 300-500 feet of decent road to land and take off. Loading could be done using a portable tank truck rather than a fixed base like the spray planes. Also, because of the increased maneuverability and the ability to slow down considerably more than airplanes, the accuracy of application should be much better.


Aussie in Kansas.
Well we were working on this in 2011-2013.... Jim had great plans for doing spraying ( low volume product) ...on our own land/ crops ... he had all the math worked out --- looked very doable ! His Turbo Golden Butterfly would have made a good platform ... I still have the booms, nozzles, pump, tank and mounts ...along with Tiggy-B ...ready to become an Ag-sprayer ...should the right person come along wanting to carry on the "dream"! ...of course some new tires & re-vamp of pre-rotator system are needed! ..... but the 310+ HP aviationized subaru just needs waking up out of mothballs!


Living in the Skies
I've had some experience with AG-gyros including testing an AG-tractor gyro ca. 10 years ago. All in all pusher tandem with AG tank in the back looks better than other configurations. On the other hand it is clear that gyro is good for spraying only on small fields framed by trees or other obstacles. Or, say, over hills and vineyards. On large open and flat fields any STOL airplane of the same take-off weight will win. It wins particularly because it needs twice less power than a gyro, and it can fly from rough terrain where gyro at gross weight couldn't make regular safe and short take-off rolls unless it has very effective prerotator and very special landing gear. Gyros are absolute winners in strong and turbulent winds but - spraying isn't applied in that condition. One more gap in gyros for commercial use is that it needs much more time for recharging - it needs time to stop rotor and then to prerotate it each time.
Thus the conclusion was that gyro could be used for AG-spraying if you just want to fly gyro and it is possible to convert your gyro time to time from 2-seater to tanker and back to make some small volume AG-job.
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Years ago, I helped support an ag helicopter-a Bell 47 with a 50 gallon tank and a spray boom. I would park his flat bed trailer next to the field he was spraying so all he had to do was land on the trailer refill from the tank on the front and quickly be back spraying. Never shut down. Promised to teach me to fly it, but hit power lines while on a photo job...
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I believe Magni showed an ag setup for their M16. The problem in the USA is using an Experimental Homebuilt aircraft for commercial purposes. A friend of mine in Colorado uses his M24 for coyote spotting, checking fences and cattle and other useful things on 55,000 acres. But only on his own property. I always thought one of the ‘1930’s tractor gyros would have made a great crop duster, unfortunately, after WWll, Stearmans were for sale for cheap...with lots of FW trained pilots to fly them.


Active Member
Spraying in action - earning with your gyro - recent photo from Ecuador - Magni M16 - photo from Magni Twitter feed HC-U0105_M16_2018_ecuador.jpg


AR-1 gyro manufacturer
I had an interesting conversation with the gentleman from Ecuador for spraying in the M16. He has 15 minutes of spray time with that tank. He makes the tank and spray system and installs it because according to him Magni takes too long and charges too much. Charging too much is a relative term because I certainly was not interested in working on this project for the money he was offering.