Bensen rotor, 3 blade Mac prop, other 3 blade prop??

[BrianInVa]

Hi folks,
I brought home a Brock KB2 this weekend. Due to my weight I may need to upgrade to a larger rotor. The original Mac is long gone so I’m dropping the KB2 keel to accommodate a Rotax 582 and proper diameter prop, and I’m considering a new larger Razor rotor, as well as a tall tail. So the Mac 3 blade prop will also be available.

I have the original Bensen rotor, but I don’t know an honest value for it yet nor for the prop. There’s also a second unassembled prop but I’m not certain what engine the hardware is for.

Any advice on their worth?

Anyone interested?

 

[GyroChuck]

The prop is a ground adjustable Ivo-prop. Fits Rotax bolt pattern. Price depends on prop diameter.

 

[BrianInVa]

The prop is a ground adjustable Ivo-prop. Fits Rotax bolt pattern. Price depends on prop diameter.

Thanks.

There are two props. One is fully assembled and looks to be 52”. The other is not assembled but appears to be the same size. I’m not sure how to measure prop size with a three blade prop.

 

[Sv.grainne]

Diameter

 

[WaspAir]

...may need to upgrade to larger rotors ...m planing new larger Raven rotors...

I have the original Bensen rotors...

Pardon me getting picky and annoying, but since you're just starting out, maybe I can influence your choice of vocabulary to avoid a common misuse that always bugs me. Your gyro was designed with only one rotor. It is made up of multiple blades. Nobody has plural "rotors" on a gyro. Helicopters often have two, with one main rotor and one tail totor, and sometimes a whole bunch of blades that make up each.

Thanks for humoring me.

 

[BrianInVa]

Pardon me getting picky and annoying, but since you're just starting out, maybe I can influence your choice of vocabulary to avoid a common misuse that always bugs me. Your gyro was designed with only one rotor. It is made up of multiple blades. Nobody has plural "rotors" on a gyro. Helicopters often have two, with one main rotor and one tail totor, and sometimes a whole bunch of blades that make up each.

Thanks for humoring me.

Thanks! Yes, I’m a complete neophyte, and still learning the proper terminology, which is more difficult following a history of serious CNS injury. So please excuse any foibles; I do catch on quick.

 

[BrianInVa]

Diameter

The currently assembled prop is 52”. I am uncertain of the unassembled prop diameter though it’s similar. I’m away from home for the weekend so I’ll take measurements when I get back.

 

[Doug Riley]

Wasp, there are lots of those terminology and spelling boo-boos to be found on this Forum. "Benson" may the most unforgivable. Rudder "peddles" make my teeth hurt, two... er to... er too.

OK, comic snobbery aside:

Brian, to measure your disassembled prop, you should assemble it. The hub will add a little to the diameter, so you can't tell exactly from the blades alone. This assumes that the loose blades aren't just spares for the other, assembled prop.

 

[BrianInVa]

Is it possible to achieve some of the effect longer rotors have on lifting capacity simply by the use of a longer hub bar to get more rotor diameter?

 

[Aerofoam]

Is it possible to achieve some of the effect longer rotors have on lifting capacity simply by the use of a longer hub bar to get more rotor diameter?

Yes, to a point....

 

[WaspAir]

Wasp, there are lots of those terminology and spelling boo-boos to be found on this Forum. "Benson" may the most unforgivable. Rudder "peddles" make my teeth hurt, two... er to... er too.

I particularly notice "duel" instruction, which is what I used to provide for my fencing club. It just "brakes" my heart to see it.

 

[BrianInVa]

I particularly notice "duel" instruction, which is what I used to provide for my fencing club. It just "brakes" my heart to see it.

Your jus being judgemental they’re.

 

[Doug Riley]

On the longer hub bar thing --

As you no doubt know, Brian, rotor blades sweep an imaginary surface as they turn, and this surface is a shallow cone, not a dead-flat disk. Most blades made today have this shallow angle (about 3 deg.) built into their hubs. Most helicopter hubs go further, having hinges on the blades that allow the blades to "cone up" to whatever angle that their lift and centrifugal effect dictate.

But Bensen blades have no built-in coning angle. Bensen figured that the hub bar and blades could just flex upward without cracking. Bensen blades run at over 400 RRPM in stock form. If you slow them down by adding more hub, you are increasing the bending load on that dead-flat hub bar. So I'd be careful extending a Bensen hub. Igor Bensen actually warned about this.

Hubs with either coning hinges or a built-in coning angle are a different story.

 

[gyroplanes]

. Due to my weight I may need to upgrade to a larger rotor.

I might be able to help you. I am probably the largest guy to fly a gyro. I'll ask, how much do you weigh.

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[BrianInVa]

I might be able to help you. I am probably the largest guy to fly a gyro. I'll ask, how much do you weigh.

275lbs.

 

[gyroplanes]

275lbs.

No threat to my record (unless you start overeating, like I did) I flew a "Bensen" Rotax 532 with 23: Skywheels and had no problems (but Gary Goldsberry (and many others) could out climb me.

 

[BrianInVa]

That second 3 blade prop was actually a lot larger than the one in the images above that was already assembled.

I received this aluminum disc with the boxes of parts I got with the Brock KB2 so I assembled the blades on it tonight, if for nothing else than to use it for “wall art” in our garage.

But it turned out to be a 60” prop.



Is this a Rotax bolt pattern? Any idea of brand?

 

[Aerofoam]

You are missing the prop hub, don't torque those bolts, or you may damage the roots. the flat plate is for the pre rotator Dominator style. The pawls look like they would be for a clutch, but I don't know anything about them, so disregard that statement!

 

[Brent Smith]

That second 3 blade prop was actually a lot larger than the one in the images above that was already assembled.

I received this aluminum disc with the boxes of parts I got with the Brock KB2 so I assembled the blades on it tonight, if for nothing else than to use it for “wall art” in our garage.

But it turned out to be a 60” prop.
View attachment 1161992
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Is this a Rotax bolt pattern? Any idea of brand?

Isn't that an in-flight adjustable Ivoprop?

 

[ultracruiser41]

That’s a ground adjustable Ivo