View Full Version : Bensen On Floats
12-18-2005, 03:20 AM
Does anyone have any info on the bensen's with floats??
12-18-2005, 05:59 AM
Bad idea unless you plan on towing a gyro glider behind a boat. Ever notice you never see any gyros on floats? Thats because gyros are already pitch sensitve enough without that added drag below the CG to screw things up even more. I suggest if you want something that flys off water get a fw ultralight with pontoons. Just a suggestion. Gyros should never be put on floats too dangerous.
12-18-2005, 09:45 AM
Floats are good to help the resue squad find you hanging upside down in the water. Paint the bottoms safety orange if you do it.
12-18-2005, 09:55 AM
I have seen Bensen's on floats and Mr Bensen himself at the controls.
I guess he could only do that, because have never seen any other gyro on floats.
Magni SA (Mr. Eric Torr) had some thing in his mind but don't know what happened, as Magni does not have any adverse pitch related problems.
I would agree with Mike.
Seasonal Greetings and best wishes.
12-18-2005, 02:38 PM
SportCopter offers floats as an option and their new video shows Jim Vaneck taking off and landing on the water.
Here's some photos that were on one of the european sites.
12-18-2005, 03:05 PM
Pitbull (N.A.R) had floats as option.
I have a Pitbull and with the tractor configuration an long stable body i think that should work.
I think to by Krucker floats thats intended for trike www.4kru.com.
12-18-2005, 05:25 PM
This guy has been flying with floats, no problem!
12-18-2005, 05:49 PM
Half us dummies, including me, have had a hard time keeping them upright on firm to the ground wheels.
12-18-2005, 07:56 PM
Ever notice you never see any gyros on floats?
I have to differ with you Mike.
Years ago the PRA magazine was full of gyros on floats, and they were flying! It was a very common practice to build and fly float equipped gyros. It was a lot easier to find a lake to tow on than it was a suitable runway.
There is an issue of the PRA magazine, from years ago, that had pictures of more gyros on floats than on wheels!
We even had a guy in Wisconsin that stuck his 447 Air Command on a set of Hobie Cat pontoons, he said it needed more horsepower (Duh!). I understand his wife was fast taxiing it and hit a boat, destroying it.
I talked to the owner of a float equipped Air Command in the Pacific Northwest. He told me that the bulk of his floats are aft of the center of gravity and act more like a stabilizer than a de-stabilizer.
I'm certaily not an aeronautical engineer, I doubt anyone on the forum is, I don't recommend attempting a major modification of this kind on a pusher gyro.
I just don't want to ignore the facts. Pusher & tractor gyroplanes HAVE successfully been flown on floats.
The only gyro I would consider maybe trying floats on would be a full length Little Wing.
Even then I would EEEEERRRR on the side of safety.
12-19-2005, 06:15 AM
That 3rd picture looks like an early tall tail.
12-19-2005, 06:44 AM
I don't think the water spray would do a wooden prop any good.
I've seen what it does to an Ivoprop on a Searay, and that prop is a good bit higher up than a gyro prop.
And tougher too.
12-19-2005, 09:12 AM
The fact that Bensen and various other people have gotten float-equipped pusher gyros up and back down again in one piece does not prove they are safe. The rotor can mask the built-in PPO tendency until the right combination of high power setting and low G un-cages this killer beast.
One of my old PRA chapter-mates, Harlan Gage, flew a Bensen float gyro as both a towed glider and free-flying gyrocopter. He eventually had a serious crash from what sounds like a drag-over -- the machine tucked nose-down and just flew into the water.
OTOH, there's no reason on paper that a safe float gyro can't be built. It just shouldn't be built by simply bolting floats onto a stock land model. You need to know the aerodynamic forces created by the floats at various airspeeds and angles of attack. That is, treat the float as you would an airfoil, developing lift and drag curves for it by actual testing.
Once you have a numerical handle on these forces, you can get to work on tail surfaces that are truly powerful enough to contain these forces. Even then, it would be prudent to work with large-scale models in a real or simulated wind, before building the real thing.
My guess is that a tractor would be much more practical than a pusher in this case.
12-19-2005, 10:45 AM
From: Cierva Autogiros by Peter W. Brooks:
“Cierva C.30A Rota seaplane. (140 hp Armstrong Siddeley Civet 1). Following test-flying by Cierva and Marsh from the River Medway at Rochester between April 13 and 26, 1935, Marsh ferried the Rota seaplane (K4296) mounted on Short F.60 type twin floats from Rochester to Felixstowe. At Felixstowe, this aircraft was tested for the Air Ministry at the Marine Aircraft Experimental Establishment. During these tests, Marsh had a most unpleasant experience. On the evening of April 29 he started a test dive at about 6,000 ft (1500 m) and at 110-115 mph (188-185 km/hr) suddenly experienced a violent nose-down pitching moment that he was unable to arrest with the control column. The machine bunted onto its back and Marsh found himself flying upside-down at 3,000 ft (900 m) with the rotor below him. At this point some lead ballast in the front cockpit fell out of the aircraft, fortunately missing the revolving blades as it passed through the rotor disc. The machine then righted itself of its own accord and Marsh, who had meanwhile switched off the engine, force-landed on the open sea immediately beneath. He climbed onto a float, swung the propeller, and taxied back to Filixstowe. An eyewitness recorded that Marsh’s only comment when he reached the slipway after this ordeal was “When’s the next blankety-blank train back to London?”
12-19-2005, 10:53 AM
How does a gyro fly upside down without destroying itself ?
Maybe those anti-droop cables help support the blades while inverted.
Can't be many gyro or heli pilots survived such an incident.
12-19-2005, 11:07 AM
Man, that's a heck of a story... I would have took the train also...
12-19-2005, 12:08 PM
With gyroplanes such as the RAF-2000 and early AirComand without horizontal stabilizers and with a large offset between propeller thrust line and center of mass, the tumbling acceleration (torque/moment of inertia) upon loss of rotor thrust is so great the rotor enters precession stall and the airframe runs into its own rotor.
It is my speculation the Cierva C-30, with massive horizontal stabilizer providing damping, inverted slowly enough that the rotor could follow without stalling. The rotor obviously had enough kinetic energy to keep it going until the machine recovered. The entire sequence occupied perhaps 5 seconds. The C-30 did not have droop cables.
In any event, Marsh was damned lucky.
12-19-2005, 02:59 PM
Anybody happen to take a look at the German machine that inspired Mr. Benson? Towed by a submarine and equipped with floats. So what if it had a couple of thousand horsepower pulling it? It was doable with 1930s technology!
12-19-2005, 04:49 PM
Dr. Bensen got his inspiration from the British Rotachute.
While a young engineer at GE, the US Government supplied several of these machines on bailment to GE for test and evaluation. Bensen performed the test flying.
Notice the overhead stick.
12-19-2005, 06:23 PM
Towing a gyro with floats isn't the same as free-flight with floats. The tow cable exerts a stabilizing force that isn't present in free-flight. That's why it is so important to have a lot of tail surface.
The German "Wagtail" didn't operate with floats anyway, it was reeled back onto the submarine's surface and folded up and stowed.
12-20-2005, 10:47 AM
We had a club member put a Bensen on floats 30+ years ago. He thought the floats, as designed, were too thin so he doubled the thickness (and weight) of the plywood skins. For some reason he modified the float's "step" by moving it forward.
From what I heard he had easy going. He backed the floats up on the beach, propped the MAC, got back in the seat, cranked in some thrust and sailed out into the lake. He started water taxiing the bladeless gyro.
As the gyro started to came up to speed, Joe hit the throttle to takeoff power. At that exact time the bow wakes converged in the center, between the pontoons, right under the 4000 RPM propeller.
Witnesses on the shore said there was an enormous rooster tail of water.
After he taxied back in he found the metal leading edges were completely gone and his prop was a nearly useless stick of wood.
Part two and three of this story are even more amazing.
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