tractor design

[WHY]

to all

Anyone thinking about building a tractor design of their own should by all means get a copy of the PRA magazine, ROTORCRAFT, August 1987 or get a photo copy of the article by Ed Alderfer on page 10 continued on page 21.

The article is small , the importance big, and the value pure gold. This article could save you much pain (financial and physical)

Tony Stiles

[magilla]

Looking into buying/modifying Joe T's JT-2. Would like the info you mentioned!!

Can you send me a pdf or a link to the article???

[WHY]

Hi Spencer

I just shipped my copy off to a friend, or I would photo copy it and send it to you. I bought my copy this year at Mentone at the convention, they do have a few copies of that issue left, you might be lucky enought to be able to get one yet. They were $5 each, don't know if there will be shipping or not.

By the way Joe's machine meets the specs stated in Ed's article.

Tony

[WHY]

By the way Spencer I have a Cont. 85-12 85 hp basket case with prop and rebuilt case that came off my Ercoupe that would take about 2000 to build up will take 1500. will not sell or ship, buyer must come and look at it personally, if interested talk to Ron there about using such an engine.

Tony

[WHY]

Just spent a great afternoon yesterday with a fellow "tractor enthusiast" discussing tractor design and theory and sure learned a lot. It is sure obvious that Ron Heron must have put in a ton of hours in research and study in making the Little wing because he has demonstrated that he has it right, for the rest of us it is also obvious that there is a lot to re-learn from the "old masters" of the past about the tractor.

At the moment there is a lot of discussion about all the design do's and don'ts on the pusher style gyro's but it is quite obvious that as the tractor comes more and more in use it is going to have it's fair share of "must do's and MUST NOT DO'S" when desigining. My friend (i won't give out his name yet because I don't want him swamped with question and e-mails) is one of those guys that puts "the pencil to the Paper" and crunches the math and comes up with the numbers that save a lot of trial and error headaches, unlike me, I put the pencil to the paper then crunch metal and go back to the drawing board to try to figure out what went wrong.

It looks like he has come up with about a dozen "thou shall " measurements and basic design rules that will be of interest to all interested in tractors, but will let him give those out later.

What gets me so excited about his gyro is that he has made a simple to build design that is light weight and will apparently fly well on 45 to 50 hp. At the moment he is in the steep part of the learning curve (the high speed taxi phase) and has already learned that the craft is thoucheeeeeee in ground steering but has some possible soultions coming up once this is overcome the next phase is the flight characteristics. Like myself, he does not want to announce per-maturily and cause any problems for others that may want to follow his design, because as I said this is going to be a nice simple design and easy construction.

It's just great to see some others with real interest in the tractor, doing some real intense development, and this man has really been intense.


Tony

[rtfm]

Hi,
So many words, so little info. C'mon mate, why all the cloak and dagger stuff?

Regards,
Duncan

[dragonflyerthom]

Tony

Your friend can eliminate alot of the ground handling problems by going to the four wheel design of the pusher. This will also allow him to balance the tractor just like the pusher also. The front wheel will keep the gyro from tipping over on take off. The tricycle gear will allow for ground taxiing and give him some control on T/O. I can see many advantages to the tractor design ie center line thrust, positive control at low speeds, less yaw effect at high speeds, and lower hp requirements.

Just a thought


Thom

[magilla]

WHY - when you get the copy back of that PRA mag, would sure love to get a copy.

When I get back to Arkansas in about a week, I am going to go to Fayetteville and most likely buy Joe Terminella's JT-2 (open frame tractor).

I am planning on modifying it slightly to put a tricycle configuration, and would love to have some of the engineering do's and dont's to do so.

I am talking with Steve Bennett of Great Plains VW, and am looking at the 120hp water cooled VW with redrive, and a Kiev 3-blade 72-76" prop. That should put my thrust numbers about 500lbs, enough to make the 600 lb machine fly. With me in it at 270, it will weigh about 870 with gas...

Anyway, I would appreciate some uncloaking of the secret info!!

Thanks,

Spencer

PS - I take my final checkride tonight to become a D/N/NVG Instructor Pilot in the UH-60. Gotta go study :rapture:

[WHY]

Hi Spencer

Don't know for sure when I'll get that ROTORCRAFT August of 1987 back with Ed's article, but the main point of the article was the important spacing of the rotor between the prop lline and the rudder hinge line and that was to have at least 20 percent more moment arm behind the rotor than in front (60 percent behind and 40 percent in front) or more.

Joe's machine already has incorporated this, so your ok. If you go to tri gear about the only additional experimenting that you will have to do is the location of the main gear to give the desired balance on the ground both empty and loaded, sorry but I can't give any experience or advice here but would think it would be about the same as would any tri-gear fixed wing set up, it might be slightly back farther because of the leverage from the height of the rotor pushing back on take off.

After reading Jim Eich's story of Arliss Riggs (PRA ROTORCRAFT DEC. 1977 and APR 1978 ) I might even change my mind about taildraggers,Arliss built a couple of taildraggers and then only built tri-geaar after that, but At the moment I think the taildragger is the best option for grass strips, but I could be wrong again!

Nothing really "secret" about the info I mention in another post, I just posted that to let those of us that are interested in the tractor know that there is serious experimenting going on with the tractor in the "simple design department" and there should be some good info coming out shortly, maybe in a couple of months depending on weather. Didn't give out any names or number because I think that when this person post his experiences and results here, he is going to be swamped with e-mails and calls and he wants to have as much correct info as possible and not have to go back and correct post because of something he has learned a short time later, just trying to be considerate on his part.

If you get Joe's machine you might consider a light weight fabric covering on as much as possible, open frames are about as aerodynamic as a brush pile and use up a lot of power overcoming the drag, a pound of weight is a pound of weight but a pound of drag is a monster that multiplies.

Tony

[Airone]

A friend took a photo of the Aug 1987 article on "Learning about the Tractor"
the file was to big to post but you can email me and I will forward the 2 photo's he sent me.

windstar_aviation@yahoo.com

Jon P. Gardner

[rtfm]

Hi,
Thank you so much for the photos of the Tractor article. Very short, but quite insightful. Not at all what one might expect.

However, I have one difficulty. Try as I might, I can't come up with a Tractor design which violates his "Law". Basically he is cautioning that with a Tractor design, the rotor head must be as far forward as possible - certainly further forward than half-way between prop and end of tail.

But just try it - try to design a Tractor in rough on a scrap of paper which is half-way reasonable (ie without violating the adequate tail surface rule-of-thumb) and with a reasonable CG, but which has the rotor head far enough to the rear to break the Tractor article's riule. I'm not sure it can be done. Since the engine is up front, the rotor head HAS to be between the engine and the pilot for CG reasons. And if you design in sufficient tail surface to give you reasonable rudder authority, you're going to end up with a very strange looking flying thing indeed if the rotor head isn't quite far forward, in fact.

I think this might be just a storm in a teacup.

Regards,
Duncan

[thirdy8special]

You might speak to Mike Guard of OKC about steering. Believe he put softer steering tailsprings(between rudder and tailwheel) to help with ground steering. He said he couldn't taxi till he installed softer springs.

[SNelson]

Hello Gary

You may research Michael’s postings regarding ground handling. I believe he had to reposition the Mains in relation to center of gravity and add toein, to improve ground control. I am sure he would be helpful with knowledge from his experments.

Cheers Sig

[chuter]

You're both right; I moved the main gear back, and changed the tailwheel steering springs to softer ones.

Now that I'm thinking back I remember that I actually did try a locking tailwheel for a very short time. I made a mechanism that would allow me to engage and disengage the lock from the seat.

I didn't even make it out to the runway before deciding it was no good.

Once you lock it you'd better have it pointed straight down the runway and hope it doesn't change before you get rudder control.

I went straight back to the hangar and took that mess off.

Doesn't mean it couldn't work for someone else though.

[thirdy8special]

Hey Michael,
Enjoyed the fly-in(and food). All four of you looked great flying together. Thanks for the ideas. Good luck with that safety on your prop.

Gary
Tyler, TX

[chuter]

Hi Gary, I hadn't connected you to your username until now (duh). Glad you made it up, thanks for making the drive.

[magilla]

Chuter:

I am buying JoeT's open frame "JT-2" gyro. Once I pick it up (tomorrow), I will probably be asking you some questions about your build. Would love to have some close-up pics of your tailwheel, landing gear, tail feathers, etc.

Big Q is: Have you considered enclosing frame to reduce drag??

Anyway, I hope to join the gyro flying community next summer.

Right now, it's tailwheel gear and engine, or vice versa.

Man, I have not been this happy in years!!!

I got a new gyro, naner-naner-naner.....:hippie:

[chuter]

Hi Spencer,

Congrats on your purchase!

As far as airframe drag goes, I've thought about it but never seriously considered it. I know I could pick up some extra speed and fuel economy by covering it, but I just like the open look, and I REALLY like being able to inspect everything.

It's also much easier to make changes, add little things here and there, which I seem to do frequently.

I think I would look more seriously at some type of removable aluminum panels to cover it before I would use fabric.

[rtfm]

Hi,
Congratulations on the Tractor purchase. I think you're going to be very happy with it. I also think that removable .025" or even .017" aluminum panels is a good idea. And no need to go with 6061-T6 either. Just the cheap stuff, since it is carrying no loads.

Regards,
Duncan