Here's a ground and flight evaluation test of the CallAir A-9 Contactflying (Jim) notes above he flew:

https://apps.dtic.mil/dtic/tr/fulltext/u2/671079.pdf

The handling and flight characteristics are interesting, especially the boundary layer profiles and source of a LE geometric discontinuity. The wing tips used were the precursor to the Hendricks/Sullivan (Hoerner design) STC commonly used on high wing Pipers, often with a span extension. The rolled and drooped leading edge worked according to the evaluators. Something like Crosswind STOL's LE cuff but more extreme.

What's not to like? Ground handling and anti loop-de-loop tendencies must have been good given the all-up weights of 3400# with a full hopper.

Gary

contactflying wrote:A9
I sprayed many years in the old days and don't know of nor have ever seen evidence of any having ground looped.

Thats cause you can't ground loop a tank


[emoji1787]

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I hope BluNosDav knows that everyone is just havin' fun among themselves here!
From where I sit, nobody is making fun of what was an honest question. But I think that ship has long-since sailed.

What size bushwheels do I need for ground-looping, and should I have three or six bolt wheels for the manoeuvre?

Battson wrote:What size bushwheels do I need for ground-looping, and should I have three or six bolt wheels for the manoeuvre?

Hmmm... I guess that really depends on what axis you're ground looping around....?

Battson wrote:I hope BluNosDav knows that everyone is just havin' fun among themselves here!
From where I sit, nobody is making fun of what was an honest question. But I think that ship has long-since sailed.

No worries what-so-ever! It's been quite an enjoyable ride. I was hoping to get a short list of fairly stable models, a short list of not-so-stable models, and maybe a bunch of models that are somewhere in-between. In the end, I kinda got that, plus some aerodynamic lessons, a couple of challenges, plus a hellava lot of good humor, and even a poem. Quite a full set of responses!

All things considered, I'm beginning to wonder if airplanes are ever examined by consumer protection groups in the same way as automobiles; will Ralph Nader write a book entitled, 'Taildraggers, Unsafe At Any Speed' ?

Thanx for everything, Dave.

How about this barnyard logic...draw a triangle with a base leg between the front wheel span and then two sides tapering back from them to the tail wheel. The longer the sides compared to the base span the better. Moooooo!

Yea there''s some CG vs tread llne station and tread width to consider but that's too much for us critters.

Gary

PA1195 wrote:How about this barnyard logic...draw a triangle with a base leg between the front wheel span and then two sides tapering back from them to the tail wheel. The longer the sides compared to the base span the better. Moooooo!

Yea there''s some CG vs tread llne station and tread width to consider but that's too much for us critters.

Gary

Sorta, but try out a Cessna 190/195 and see how that works there.....

MTV

Some are just 'born to be wild' - https://backcountrypilot.org/forum/cess ... pion-15689

Plus proper planning prevents piss poor performance...or training as suggested above.

Gary

The ones that are flown properly

mtv wrote:

PA1195 wrote:How about this barnyard logic...draw a triangle with a base leg between the front wheel span and then two sides tapering back from them to the tail wheel. The longer the sides compared to the base span the better. Moooooo!

Yea there''s some CG vs tread llne station and tread width to consider but that's too much for us critters.

Gary

Sorta, but try out a Cessna 190/195 and see how that works there.....

MTV

Yep - the distance between the CG and the main gear is what matters most, if memory serves. Probably been said already, but I am not going to check five pages.

CG's back from the front gear then they add a big azz prop to absorb all that radial engine power. That means tall narrow spaced gear for prop clearance so nobody can see forward and the loaded weight moves even further back tail down. Then to rear end it they install a small marginally effective rudder and wonder why all the ground action.

Great review: https://www.aopa.org/news-and-media/all ... cessna-195

Locally there's one that lives in a nice hangar. Years ago in Northway Alaska (International POE for some) Floyd Miller flew one and mentioned to me he really liked that airplane. Some of the strips he went into were short and narrow but he was up to the task.

Gary

Triangle ratio - Width of gear legs vs length of tail. Equal distance width to length is probably the ideal but not very practical...

Center of Gravity related to triangle ratio. Most forward = less tail inertia but more prone to nose over...

Rudder size: The bigger, the better: Like most important things in life.

For the Aeronautical engineers in the crowd; are there other factors in the formula?

PA1195 wrote:CG's back from the front gear then they add a big azz prop to absorb all that radial engine power. That means tall narrow spaced gear for prop clearance so nobody can see forward and the loaded weight moves even further back tail down. Then to rear end it they install a small marginally effective rudder and wonder why all the ground action.

Great review: https://www.aopa.org/news-and-media/all ... cessna-195

Locally there's one that lives in a nice hangar. Years ago in Northway Alaska (International POE for some) Floyd Miller flew one and mentioned to me he really liked that airplane. Some of the strips he went into were short and narrow but he was up to the task.

Gary

Actually, engines aren’t that big. Biggest is 300 (yes, I realize there’s ONE out there with an R 985, ONE) hp. 185 same, but a lot friendlier on ground.

MTV

While having made many takeoff and landing in Steadman spraying, I have no C-195 experience. Visibility was bad with the 4" hopper lip above the fuselage where the front seat had been, but the apparent brisk walk rate of closure (not allowing apparent rate of closure to speed up on short final) got me on slow and soft with that big Hamilton Standard still blasting the rudder. Always leveling the airplane, at the last minute, allowed me to see the runway to the edge on both sides for longitudinal axis alignment. The airplane, with two wings and flying wires and braces, long gear, spray boom and nozzles, and square hopper lip, was plenty dirty but power controlled the attempt to sink. Touchdown was very slow. Sorry, for those wanting a number, it had no airspeed indicator.

Landing slow worked for every airplane, most every small American tailwheel, I flew. Bad things happen less often at slow speed whatever we fly or drive.

I don't think width of the landing gear affects the tendency to loop, just how the plane will react and how controllable it is once the loop has started. Guessing here!

I did some quick searching and realized the book I was going to buy never happened: General Aviation Aircraft Design: Applied Methods and Procedures by Snorri Gudmundsson

It's about $125 now in paper but was almost four times that back five years ago. I should order one and learn something. At over a thousand pages I'll need a new bathroom by the time I'm done reading.

Gary

Battson wrote:I don't think width of the landing gear affects the tendency to loop, just how the plane will react and how controllable it is once the loop has started. Guessing here!

That’s an interesting point: there’s a wide-gear option when converting to a PA-22/20. It’s said that they are more docile than the original, narrow gear PA-20.

But I’ve flown a PA-16 for a decent amount of time (narrow gear) and my spring gear is definitely wide, but I didn’t notice a difference between them as far as a tendency to swap ends goes.

From Roskam:

Thinking out loud...

Some of the main problems with controlling a ground loop at low speed appear to be differential brake action and the overturning moment lifting the inside main landing gear off the ground. Thoughts?

So if the wheels are further apart, then both differential braking and the weight on the inside wheel are improved, making the loop much easier to arrest or control - effectively delaying the "point of no return" until the plane is deeper into the loop.

However, I think that benefit has little to do with the unbalanced forces causing the loop in the first place. Going out on a limb here!

If we touch down at the speed of stall in ground effect, we need only roll a bit until panick breaking wouldn't cause a wheel to come off. It generally causes the airplane to go on the nose at a speed that wouldn't cause damage in a ground loop.

Because I didn't have good brakes and taught in airplanes that didn't have good brakes and especially because they tend to cause damage, I never used or taught differential breaking. I know it can save a pilot from ground loop. I have just found good speed control and good rudder usage to be more effective.

Little airplanes were not designed to be well controlled at touchdown speed requiring brakes to get stopped in a thousand feet. Cleveland brakes later became standard and most older airplanes have them now. They help with taxi, especially in a strong crosswind. They have also caused a lot of damage.