A different Tractor [Archive] - Rotary Wing Forum

mceagle

11-15-2003, 06:35 AM

The attached photo is proof that you can have poor designs in either tractor or pusher configerations. The gyro pictured had a very short life span, and anyone that knows anythong about gyros can see why. http://www.rotaryforum.com/attachments/Freds_Tractor.jpg

rehler

11-15-2003, 06:40 AM

Whatever your name is, please tell me why?

Brent_Brown

11-15-2003, 08:29 AM

No HS ? needed more training?

Joe_Terminella

11-15-2003, 08:29 AM

whats up ?.......looks pretty cool to me

GyroRon

11-15-2003, 10:00 AM

My bet is the blades smacked the rudder on takeoff.

Al_Hammer

11-15-2003, 12:48 PM

Looks like the rudder might be  non moveable. Here are a few other tractors for comparison Designs by  G. Pate,  D. Gittens, V. Jones,  R .Herron.

Aussie_Paul

11-15-2003, 01:02 PM

Tim, it appears to me that the offset gimbal is the wrong way. Aussie Paul.

Udi

11-15-2003, 02:36 PM

I like the one that looks like a lawn mower.  That's the most creative gyro I have ever seen.  Did it ever fly?

Brent_Brown

11-16-2003, 02:20 AM

Can you all repost the photos?

mceagle

11-16-2003, 06:53 AM

Ken Rehler, My name is at the botton of the post. The C of G of the Gyro is 2ft behind the rotor thrust vector, which meant (among other things) that the balance test would have been tail down creating unflyable instability. The main wheels are so far ahead of the C of G that ground handling with a short fuselarge would have meant one ground loop after another. The fuselarge itself is a very efficient "drag machine". Not so obvious is the extreme degree of pitch on the propeller, on the sound theory that if a gyro does 70mph with 28" pitch then it will do 140mph with 56" pitch. Most of these problems could have been overcome before it's first "flight to destruction" had the designer been prepared to seek advise before embarking on the final construction.

Al_Hammer

11-16-2003, 08:18 AM

The rotor thrust vector is not fixed, it moves as the stick is moved. If the hang test showed a tail heavy configuration(and it sure as heck is not obvious from the photo where the cg is), then it would affect the centering of the controls-NOT the stability. If the vertical cg is in line with the prop thrust and  the rotor thrust vector passes behind the cg, then it indicates stability. Being tail heavy , in itself does not affect stability because the rotor thrust vector is simply moved as required to pass thru the longitudinal cg to keep things balanced. The problem is that you run out of range on the controls if the hang test is too far off. To Udi: as I recall, the Gittens (lawnmower) tractor has not flown, but I could be wrong. Actually none of the gyros pictured have flown to my knowledge, except for the Little Wing.

rehler

11-16-2003, 09:43 AM

Tim, Sorry, I didn't see your name at the bottom.  I was looking at the top left and then clicked on your profile to fine your name.  I need to look at the bottom - still getting used to this new forum. It now does seem clear now that the pilot would be heavier than the engine and the CG would be way out of position to allow flight.  Looks like (if somehow the rotor head could allow enough forward movement) that it would fly with the nose sticking way up and the tail way down. If the engine was moved forward or the mast moved back it might do ok.  It looks like a fun gyro overall - draggy like a Bensen but fun.

mceagle

11-16-2003, 10:03 AM

Al, I have tried to do a quick sketch to show the RTV relationship to C of M, as accurately as I could draw it. (click on paper clip above) Estimations are approximate. The 160 lb engine is 2 ft ahead of the RTV *while the 180 lb pilot was 3 ft behind *the RTV. The fuel, fuselarge, rudder and tail wheel are all further back again. One of our blokes who are more proficient with figures should be able to give us a rough approximation of the C of M. Gyros, as with all aircraft, should have the C of M ahead of the thrust vector (lift), not behind it. In this case it would lift the main wheels well before the tail wheel which would make cross wind operation impossible. * Another problem that I could forsee with this particular design would be the effectiveness of the rudder working in such dirty air. Ken, I agree with you - I think the problem areas could be fixed and it could well be a fun machine, might have to wear goggles though.

Al_Hammer

11-16-2003, 10:22 AM

Tim,  I cannot view the doc unfortunately, due to a  prob with my PC.

mceagle

11-16-2003, 08:56 PM

Re Relationship between Rotor Thrust Vector and C of M Al, I thought you might change your mind when you edited your post. Seriously though, I realised that you had simply got it back to front because I have read your posting on Norms forum - "Theory of Flight - Rotor Thrust line - Al Hammer - 10/19/2003, and you got it right back then. I don't know why you could not open the attachment on my last post. It is only a Microsoft Word Document. Perhaps some one else could let me know if it opens OK

Brent_Brown

11-16-2003, 10:38 PM

Al the lawnboy flew and was best in show both PRA and FAA

Brent_Brown

11-16-2003, 10:39 PM

this is one of his  too

Al_Hammer

11-17-2003, 01:47 AM

Thanks Brent, I did not know that the Gittens machine had flown. We learn something new everyday around here. Tim, you caught me. I did type it backwards.  How embarrassing.  ;D I do still maintain that the fore and aft weight balance is not what determines whether the RTV is behind the cg or not. If the prop thrust line is high(HTL) and there is no H-stab, then the RTV must pass in front of the cg to balance the pitching moment. I'll be updating my computer soon to something a little more recent than a 133mhz pentium with windows 95, and then I'll be able to view word docs with images in them. :D

RHerron

11-17-2003, 11:39 AM

I agree with Ken R...the little machine isn't any worse than some of the others pictured...plus it is stronger. Of course, it needs the obvious...a tail. Don't be too hard on the guy.

JoeSwanton

12-07-2003, 11:17 AM

Is this the machine that was partialy built at the Texas PRA convention? If so then it had weight shift rotor head that also tilted. Very far out there. Truely an experimental machine. The ground loop potential looks good also. The lack of a horizontal stab sent shivers up my spine.

RHerron

12-10-2003, 03:05 PM

Joe,

How are you?
No, this is not the machine you are referring to.
The one at PRA Waxahatchi was MUCH worse. As configured, it would be unsafe to fast-taxi, much less fly.

gyromike

12-10-2003, 05:19 PM

Are ya'll talkin' about this one?

MMorgan

12-11-2003, 05:34 PM

that is really scary looking...mike, you never showed me this pic before, where did you see it?? did you see it fly??

the other mike

gyromike

12-11-2003, 07:30 PM

Mike,

that one was parked by the row of campers not far from where me an Kevin were camping at. It didn't fly, it was just a static display.

I wonder how well that type of head would handle the 2/rev vibrations?

GeneWeber

12-12-2003, 04:16 PM

Hi Folks,

The David Gitten’s “Lawnmower” is named the Ikenga. He was a presenter at the Hofstra conference and showed photos of it flying. He is a very creative and unique individual. The spirit and soul of an artist.

Regards,

Gene

rfi

12-13-2003, 08:38 AM

The Gittens tractor gyro, the Ikenga has flown. I took video of it at the PRA convention at Middletown, Ohio in 1989. I knew David Gittens during that time frame since we both lived in the same town (ABQ, NM) and belonged to the same gyro club.

girogeorge

12-14-2003, 05:20 PM

I can't remember what the felows name was , but, he said he was an engineer...His machine work was excellent, although I wonder as to if he really understood the forces and stresses that are imposed on gyros would be too much for the frail-like components...interesting enough I took quite a few pics of it.....

darrellwittke

04-04-2004, 06:42 PM

The gyro pictured above must be Craig Walls latest incarnation of his Lepton. I would hazard a guess such as this from Craig's previous postings suggesting such things as the bicycle fork landing gear, direct overhead control stick, and obvious dedication to weight reduction.
This brings to mind a question I was thinking of asking the australian musterers. Craig Wall once posted his Lepton (a bensen structured taildragger with titanium bolts) was so light that it was virtually impossible to fall off the back side of the power curve. (even at low, low speeds.)
Has anyone down under in Australia also found this out? (ie. a small very light pilot on a powerful light gyro?) Will also post on aussie thread.

darrellwittke

04-04-2004, 09:14 PM

Am I seeing and deducing the rotor head correctly? (ie. a slider type head to absorb 2/rev and 4 bar linkage to automatically correct for gust/rotor thrust increases?
If those back bars are able to move ( I can't tell for sure) then it seems to me the linkage would decrease rotor disc angle when forced backwards by increased rotor thrust. A correct attempt at what RAF was trying to acheive but screwed up by crossing control rods to the front. (As pointed out by C. Beaty)
Craig Wall was quite a character, a talented engineer, and a very intelligent individual. (Deduced from his postings on Norm's forum years ago.) It would be in character for him to design a gyro that is stable for his tastes but does not employ a horizontal stabilizer, just because he can.
Can you post more pictures?

aaron hughes

04-05-2004, 03:17 AM

Fellars
The tractor gyro that mceagle is talking about was built by my father in australia this machine did fly very well.
The information that mceagle wrote is very incorrect.
I quote"&qot.flight to destruction"is not true the machine is still in the shed it is not a tail dragger any longer as he changed it to front wheel steer.
That machine as i said flew very well and i add as he didnt.the photo was of its first flight.Look at the back of the gimble head it has a handbrake there which made the head c of g for the thrust adjustable in flight the tail did not hang down as i was there for the hangtest.
This machine did many hours although not perfect in the early days,after many changes had a fine tractor machine.
The gimble head was back to front for the start but then was changed to the joystick between the legs making it normal.
THe hs well fellas it has a small one now ,but he worked on the theory that the thrust of the propellor would zero out the thrust of the main rotor making a very stable machine.

gyromike

04-05-2004, 03:29 AM

Darrell,

I spoke to the fella who built the machine you're referring to. I don't recall his name, but it wasn't Craig Wall.

It's not a slider type of head though. It's more like a weight-shifting design. Move the stick forwards, the head moves backwards, shifting the CG forward, tilting the disc downward, etc.

It looks like a solution in search of a problem.