Flying characteristics of a Bensen gyro.

[royden]

Hello to you all.
This is a question to all of you pilots with flight time in the Bensen B8m gyrocopters. What is the Bensen's flight characteristics like? Does it have any nasty tendencies to watch out for. Would it be a good, safe "first" gyrocopter for a newly certified, low time gyrocopter pilot?
Any info about flying a Bensen will be appreciated.
Roy.
South-Africa.

 

[Resasi]

Hi Roy, the Bensen B8 was my first single seat gyro. Under LASORS (The UK regs at the time) I had to do 15 hrs dual on an RAF 2000 before transitioning to single seat training. The RAF 2000 I was trained on was the stabless, (no horizontal stabiliser) version so was much lighter on the stick, but going to the Bensen was a whole new dimension in the sensitivity of control feel and input. Not as important and exercise for two seaters In terms of longitudinal stability think of it/an analogy, is like progressing from a bicycle to a mono cycle, the degree of balancing required on a single seat gyro is much greater...and very important.

One of the principal exercises in the Bensen was wheel balancing. The fine art of running down the runway just fast enough to be able to use the rotor to balance the gyro on its main wheels without allowing either nose of tail wheel to contact the runway. This when it can be consistently done the length of the runway is the vital clue to your Instructor that you are mastering the finer inputs that show him you will not over-control when you get airborne, as pilot induced oscillation is extremely likely, and dangerous for low time beginners.

Pilot-induced oscillations are sustained or uncontrollable oscillations resulting from efforts of the pilot to control the aircraft. They occur when the pilot of an aircraft inadvertently commands an often increasing series of corrections in opposite directions. Each an attempt to cover the aircraft's reaction to the previous input with an over correction in the opposite direction. An aircraft/gyro in such a condition can appear to be "porpoising" switching between upward and downward directions, this can lead to the gyro becoming out of control...obviously a most undesirable state of affairs.

It took a bit of time but when you ‘get the idea’ you then cary on the succeeding exercises leading up to the PPL. My Bensen did not have a prerotator which involved 'patting up’ the rotors and was invaluable in teaching me rotor management. After the PPL I was lucky to be amongst a big crowd of gyro pilots and over the next couple of years was able to transition to and fly various single seaters like the Cricket(s), Merlin, Layzelle AV18 single seaters before then building a Hornet with my son. So I have been able to compare various single seat gyros.

The Bensen was my favourite...in that it was very light on the controls and very agile/nimble compared to the others, with no ‘nasty tendencies’, but here’s the caution, very light on the controls nimble and agile all go with stability. That particular Bensen, every gyro is to a point very individual in its flight characteristics, I later felt was the one I had to watch the closest. All the others were more stable ie easier for the beginner.

I had no problems but I was fortunate to have a lot of time on a larger variety of aircraft type from gliders to heavy transport, which actually doesn’t necessarily make a good gyro pilot, simply familiarity of time in the air and with the huge range of flying machine handling characteristics.

Whatever two seater you have trained on the Bensen will be the monocycle. Learn on it carefully and you will love it, simply know that it is a great flying experience, but as they all do, needs to be treated with respect.

Hmmm bit of a waffle there but hope it helps. P.S Loved the Excel.

 

[Resasi]

Having some fun on the Bensen in the early days with friends on a breezy day.

 

[wolfy]

Your an ace Leigh

wolfy

 

[Resasi]

Thanks Wolfy, but in gyros still a newbie.

 

[HobbyCAD]

Roy, have you found an original Bensen in SA? May be one of the originals I built for Ben Groenewald back in 1984. There were 4 or 5 kits imported, I built them, rebuilt some ex-SAAF 72HP Meteor engines I sourced from AFS Snake Valley, and one or two 90HP versions that came from Jan Boezaardt. The business came to an abrupt halt when Ben had a major mishap at Lanseria, trying to solo-start hand-prop one for a prospective client.

There was one gyro glider, we did training at Jan's strip east of Pretoria, a couple of seconds of flight each run, but invaluable flight experience before going solo on the B-80's.

Cheers, F.

 

[royden]

Roy, have you found an original Bensen in SA? May be one of the originals I built for Ben Groenewald back in 1984. There were 4 or 5 kits imported, I built them, rebuilt some ex-SAAF 72HP Meteor engines I sourced from AFS Snake Valley, and one or two 90HP versions that came from Jan Boezaardt. The business came to an abrupt halt when Ben had a major mishap at Lanseria, trying to solo-start hand-prop one for a prospective client.

There was one gyro glider, we did training at Jan's strip east of Pretoria, a couple of seconds of flight each run, but invaluable flight experience before going solo on the B-80's.

Cheers, F.

Hi Hobby CAD.
I had no idea you were in South-Africa. I did have my eyes on a Bensen that was one of Ben's kits that had been built. The engine was replaced with a VW 2180 with a downdraft carb. I saw it fly out of Baragwaneth (Syferfontein) and it performed really well. Ever since then, Ive had the idea of getting or building a Bensen for myself just to fly around locally for the fun of it. I wasnt able to find what happened to it after I saw it fly out of Bara.
Thanks for the info.

 

[HobbyCAD]

A Bense

Hi Hobby CAD.
I had no idea you were in South-Africa. I did have my eyes on a Bensen that was one of Ben's kits that had been built. The engine was replaced with a VW 2180 with a downdraft carb. I saw it fly out of Baragwaneth (Syferfontein) and it performed really well. Ever since then, Ive had the idea of getting or building a Bensen for myself just to fly around locally for the fun of it. I wasnt able to find what happened to it after I saw it fly out of Bara.
Thanks for the info.

A Bensen B8G or B8M is an easy machine to build. There are complete plans for those, except the rotorhead in those plans is the very early spindle type, not the offset hinge type, and the blades are wooden blades. You should also be able to find a set of rotorhead plans for the Rotor Bug, they were a semi-knockoff of the Bensen head. Maybe some others exist. Metal LE or fully extruded metal blades are not difficult to find.

If you are to build a Bensen B8M, for God sake, don't raise the thrustline, or try to add more HP. The Bensen was pretty much tuned to not experience a PPO at the drop of a hat, it had too little power, and the thrustline was low. When the higher HP 2-strokes came out with the advent of microlights, they found their way into Bensen gyro's. To fit the large diameter props, the engines were mounted higher. When the wonder triangle of gyro's, CG, drag, thrust, was broken, the high powered high thrustline engine would push the gyro over, game over. You go and research and see how the fatality rate increased when they moved from Mac engines with it's short broad airboat paddle prop, to the larger diameter 2-strokes. Now you know why the spider-like tall gyro's came out, to lower the engines back down again, but the tailboom and landing gear had to drop down to accommodate the prop down low. Gyro's once again became safer....

Why not start your experience with a B8G gyro glider, learn to fly, then convert it to a B8M. It's simply changing the cheek plates and adding the engine mount, engine, tank.

Moral of the story, don't overpower a Bensen.....

Cheer, F.

 

[kolibri282]

Quote: is like progressing from a bicycle to a mono cycle /Quote
Even without any piloting experience you immediatly grasp that one, great descriptive term!

 

[Doug Riley]

I built, and taught myself to fly, a Bensen-VW gyro as a teenager. I took to heart the endless reports of fatal porpoising crashes. At the peak of Bensen fatalities, there was about one a month.

Such a crash had occurred at my practice airport. I'd visit the corroding remains of the gyro that killed pilot Andy White each time I went flying.

This all scared me enough that I progressed VERY slowly in my self-training. I probably had close to 100 hours practice (between flying the unpowered gyroglider and crow-hopping the powered one) before I first flew the pattern.

In hindsight, I think that the stock Bensen B-8M had a couple of related design flaws that Bensen chose to stonewall rather than to fix. These flaws have to do with uncompensated prop torque reaction, very low rotor damping and the absence of an effective horizontal stabilizer.

There's no reason to play Groundhog Day -- to repeat the often-fatal errors of the past. IMHO, any Bensen flown today should, at the very least, have a large, functional horizontal stabilizer. Ideally, it will have that, plus more modern blades with greater mass and lower RRPM than Bensen's rotors, plus some means of preventing torque roll (other than side-sticking, which doesn't work at low G).

 

[Mayfield]

I built, and taught myself to fly, a Bensen-VW gyro as a teenager. I took to heart the endless reports of fatal porpoising crashes. At the peak of Bensen fatalities, there was about one a month.

Such a crash had occurred at my practice airport. I'd visit the corroding remains of the gyro that killed pilot Andy White each time I went flying.

This all scared me enough that I progressed VERY slowly in my self-training. I probably had close to 100 hours practice (between flying the unpowered gyroglider and crow-hopping the powered one) before I first flew the pattern.

In hindsight, I think that the stock Bensen B-8M had a couple of related design flaws that Bensen chose to stonewall rather than to fix. These flaws have to do with uncompensated prop torque reaction, very low rotor damping and the absence of an effective horizontal stabilizer.

There's no reason to play Groundhog Day -- to repeat the often-fatal errors of the past. IMHO, any Bensen flown today should, at the very least, have a large, functional horizontal stabilizer. Ideally, it will have that, plus more modern blades with greater mass and lower RRPM than Bensen's rotors, plus some means of preventing torque roll (other than side-sticking, which doesn't work at low G).

In the early 70s a really sweet lady; Helen Devarssy (Devassey?) wrote a monthly column titled "In Memoriam" for a Rotorcraft news letter in Pennsylvania. The column remembered the folks who had died in a gyro that month. Helen and her husband Lou ran a Radio Shack. Lou was the go to guy for Mac engine magnetos. He also sold me a set of StanZ blades. I believe Chuck knew them and can make corrections if I am misremembering.

It was a vibrant time for "Gyrocopters."

 

[Doug Riley]

Jim, I think that Lou and Helen spelled their name "Darvassey."

Helen was a hoot, shamelessly referring to herself as "that meddling broad" and other such names, as she tirelessly pushed us to volunteer and write articles.

Good times, and tragic times as well.

 

[C. Beaty]

StanZ (Stan Zankowski ?) ran a radiator shop in Pennsylvania and made metal rotor blades on the side. Then there were Weillage (?) metal blades which later became Rotordyne when Weillage (a retired carpenter) was bought out by the Phaneff (?) Brothers. Both had one piece aluminum skins over an aluminum spar and both had excessively blunt leading edges.
Bensen metal blades had segmented upper skins with unsealed gaps between segments, wasting several HP as centrifugal air pumps.