Bandit Autogyro

[Mike Jackson]

Anyone have any opinions or preferably flight experience with Joe Souza's Bandit design?

I am attracted to the 4130 cage and the sub 4 stroke. Thrust line looks high but has a huge HS. In another forum I unintentionally started what became quite a "urination contest" with some "colorful" personalities. :(

Thanks,

Mike :)

[j4flyer]

I have flown Joe's ships and I have flown other designs as well. I believe Joe's ship is probably the easiest flying gyro around. It will truly fly hands off without tension springs etc. The thrust line doesn't seem to be influenced by power changes and the large horz stab is very effective. I believe his former Rotordyne partner has his for sale due to medical reasons. Rodger has the dual carb rotax 503 on it and boy does it have power. Having flown both, I like the Rotax machine. It is lighter and has performance. I haven't spoken with Joe for a year or so and I'm not sure if he is still making new gyros. His brother said he is doing mostly his powder coating business and has little time for other ventures. Good luck.

[gyromike]

That link sems to be dead.
Try this one:
http://www.rotordyne.com/index2.htm

[chuter]

From the website regarding the gearbox they sell:

"They attach easily, are oil cooled and raise the center of thrust up for even better performance."

Huh?! Raising the center of thrust means better performance? :confused:

[gyroman]

Right, from what I remember Joe was a little confused on his gyroplane aerodynamics. His website had a few incorrects statements like this.

[Texas Armadillo]

I considered Joe's Bandit when I was shopping for a kit. I called and asked him how high his thrust line was, and he said about an inch. That really put me off, because just lokking at the pictures it seems to be about a foot.

I narrowed my choices down to the Dominator and the Air Command because of CLT. I finally chose the Air Command because I just couldn't get used to the way the landing gear on the Dom looks, and the Air Command is made in TEXAS! :p And also, I was going to do my training at Caddo Mills (where Air Command is located) in a two place Air Command machine.

js

[Brian Jackson]

Looks can be deceiving... The GyroBee for example appears to be HTL when in fact it's within an inch of CLT. But I would be curious to know if the Bandit truly is an inch to CLT.

Thanks,
Brian Jackson

[chuter]

Maybe he's thinking that it performs better if he gets the thrust line as close to the top of the pendulum as possible. ;) :D

[Texas Armadillo]

Yes Sir, I know you're right, but I can believe it easier about a Bee, better than I can about the Bandit though. (Is that a screwy sentence or what?)

I always look at "CLT" in two ways, and consider both as I look at a gyro. I don't have any scientific education like some of the folks here seem to have, so I just look at it. I picture in my head a line going thru the center of the prop and heading forward thru the pilot. To me, it should hit you in the lower back or even lower than that.

The two ways I think about it is, center of mass, and center of drag. I think both are important. I also realize I have a whopping 5 hours of flying time and have only built one gyro, so my conclusions are accepted as suppositions by even myself...

Center of mass means to me, the thrust line (that imaginary line going thru the center of the prop toward the pilot) needs to pass thru the center of the weight of everything that hangs under the rotor itself. I imagine a gyro without rotor blades on it sitting still in space in zero G. If you push straight forward on the center of the prop, would the gyro start to forward tumble? It sure looks like the bandit would.

Center of drag, again without rotor blades, is the center of the prop line going thru the center of the "drag" of the wind of the gyro... this line is probably pretty close to the center of mass, but not nessasarily exactly in the same spot. And again the Bandit doesn't look good in that repect either.

I think if a gyro has a centerline, that in my mind fits the two paragraphs above, then in the unfortunate event that the rotor blades are unloaded while the trottle is high, the gyro will not have the tendency to do a PPO, or forward tumble.

I hope I didn't hijack this thread, it was not my intent.

js

[Brent_Brown]

He said some time ago that he used 1025 or ? not 4130 COMO. something about better weilding with?

[PW_Plack]

Higher performance because you can fit a larger diameter prop, would be my guess on what he's saying.

[Aussie_Paul]

The weight of the rotors has to be in the calculations as well Jeff. A good KISS post.

Aussie Paul. :)

[j4flyer]

Joe originally used 1025 steel for his airframes. When he started building ultra lights he switched to 4130 for weight reduction. Once he had a stock of 4130, he used it through out the line. I believe the CL location was based a formula Chuck Beaty presented on a conference thread of old. I think Gregg G helped Joe with the figure. I was basing my opinion on flying several brands of gyros. I found the Dominator sensitive in yaw, the aircommand sensitive in pitch, RAF sensitive in both unless equipped with a LARGE stab (then the controls were heavy), Bensens I found rather touchy in all axes, Barnetts are stable in all axes but, none of the models fit the ultralight group. Jim Eichs JE-2 was excellent in all axes but again too heavy for the ultra light group. The snowbird was pitch sensitive. I haven't flown Jim Vaneks machines, I haven't flown the new air commands, I haven't flown a sparrow hawk and I'm sure their are a couple of others I've missed too. From the group I've flown, I like Joes' ultra Bandit for the stability and power. Putting looks aside, you need to fly one to see what I'm talking about. I'm only speaking of the single place machines. I don't like the two place Bandit. Although the pilot location appears to place the CLT in the proper location, it doesn't fly anywhere near as sweet as the ultra Bandit. Anyway, that's my thoughts. Add a dollar to those and you can buy coffee (at 7/11)-Bob

[Texas Armadillo]

The weight of the rotors has to be in the calculations as well Jeff. A good KISS post.

Aussie Paul. :)

Yes Sir, I guess you're right about that now that I think a little more about it. I've always kind of thought about the rotorblades as a kind of parachute. Keep air in them and they produce lift and drag. Don't laugh at me! (grin) Take them away and all you need to consider is the thrust line on what is left. I well understand it's not a "proper" way to consider the actual aerodynamics of rotorcraft flight, but I think it's basically sound according to my my few gray cells. :D

I do realize this is a very over simplified view of it (especially after reading UDI and Al in the other thread) but you're right, even with the blades unloaded, the center of mass and drag, would have to include the rotorblades in some respect, since even unloaded they would have mass and some drag.

But, as you said, I like the KISS view. If I mentally remove the blades from my mind, I make a personal decision of whether or not that gyro is a canidate for a PPO.

Movin' out...

[Doug Riley]

Jeff: You're on the right track, but center of drag should be aligned with center of mass. Airframe parasite drag is basically "anti-thrust" -- that is, it's a force pushing back on the frame in a direction opposite to the direction of flight. As such, it can do the same thing that prop thrust can do: rotate the frame around its center of mass if the line of force doesn't pass through the C.M.

Fortunately, the airframe drag of a gyro is only a fraction of the rotor drag. It's been measured at 60 lb. or so on an unfaired Bensen at 50-60 mph.

Therefore, a center of drag that's low by X inches isn't as catastrophic as a prop thrustline that's too high by X inches. Remember, the prop thrust is around 300 lb. at full power, while the frame drag is 60-ish. The frame drag increases as the square of the airspeed, however, so it gets much more dangerous at high speeds.

I'm not suggesting that the center of drag of the gyro can be ignored. Align it with the C.M.! Why allow ANOTHER source of uncontrolled pitchover to exist? Fortunately, most of us create CLT by raising the pilot, who happens to be a big source of drag. By raising our draggy selves, we raise the center of drag and kill two birds at once.

[Texas Armadillo]

uh... would you like fries with that?

Just kidding, I understand, thanx.