Stirrable nose wheel or differential brakes.

I suspect by now the original message has long been forgotten, nobody cares and I've lost interest....

My primary trainer is The Predator, a one of a kind near centerline thrust two place tandem powered by a Lycoming IO-320.

Perhaps a one of a kind aircraft has some characteristics that are also one of a kind and its reasonable to expect they are at least unknown by me? Its also largely academic to the entire forum what you experience, and how, if it performs differently to all others.

When I fly any gyroplane with a properly adjusted trim tab at a typical approach speed with no throttle changes I don’t need any rudder pedal pressure to maintain coordinated flight.

trim tab works at one speed at a given power setting so no idea how you set yours but in Autogyro and Magni aircraft you get quite large yaw changes with power changes. Removing power (as perhaps you might accept during final.....) gives a right yaw that requires left pedal to maintain balance, but I'm telling you what you already know so its pointless explaining because... half of what is being written is nonsense because you are creating an argument nobody made with you so....

If I have a cross wind component from the left I use right pedal pressure to bring the nose right to align with the runway.

Nobody argued with that. you just got all stressed and started trying to make a point out of the fact I mentioned relaxing the left pedal due to the power changes etc etc blah blah..

I have no reason to release left pedal pressure because I don’t have left pedal pressure in to fly coordinated (yaw string or flag straight back).

In your aircraft or a Magni/AG? having removed power on final? If your one off aircraft then its totally academic isn't it?

If I have a strong enough cross wind component from the left I may get full right pedal in before touch down.

Honestly that surprises me if touchdown is at a "normal" speed material to this thread, and this is where it becomes tiring tiring to cover everything for you so that it doesn't generate 1000 ripostes. Sometimes you claim you touch down with almost zero ground roll and very low airspeed when its to grumble about...well me for example. but then the internet is a wonderful thing. and every now and then you see pictures which are worth more than words.. like this example of a landing from a guy called Vance. Around 6m50sec in for a lovely landing. sincerely meant btw.

Just so you can be clear that is the kind of "normal" landing which I'm surprised needs full pedal input at touch down. Which by the way if you did need full pedal and it were to be material to this thread then you would be inaccurately aligned and either you put too much pedal in or ran out of rudder authority. We can all make a mistake with the pedal but I'm sure nobody I know has run out of rudder authority in a crosswind - but then we tend to fly stock mass built aircraft not one offs. Out.

 
I do not agree with these opinons about hard linked nosewheels. Yes I've flown both.
A catering nose wheel and differential steering is one of the biggest safety features you will use on a daily basis besides your seat belt!

To be clear: You mean Castering nose wheel and differential BRAKES.
 
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I came on RWF today to pose a question to the community asking if anyone had ever converted a Dominator to hard-coupled nose wheel.

I found this thread and thought it might answer my questions regarding what I recently came to consider a dangerous design flaw on the later model Doug Smith designed AC airframes.

Less than 1/2 way through page 2 of this thread my mind was already numb and I quit reading and decided to post.



I have spent most of my time in "Low Rider" Air Commands and CLT converted AC's, with the original Dennis Fetters SOFT-COUPLED NW (using springs to allow the NW to go where it wants to some degree, while at the same time making it completely steerable with the pedals). This has proved to me to be a very reasonable steering nosewheel which allows a great deal of forgiveness when the tail rudder is turned to correct for (1.) cross wind and/or/plus (2.) prop wash acting on the VS while the NW touches down for any reason while moving fwd - TO, landing, whatever.

The old Low-Rider Air Commands had perhaps one of the lowest COG of any tandem. Once Dominators became popular, Air Commands (under the design of Doug Smith) followed suit and we had CLT conversion kits and newly-redesigned CLT AC's. I have always considered Dominators to be a wonderful gyrocopter, and long ago realized why the nose wheel was free-castoring: The COG is VERY high and as a result a roll over is much more likely due to abrupt weight shift with all three wheels on the ground, no matter what may cause that to happen.

In order to reduce roll over you uncouple the nose wheel and let it castor and turn freely, and use differential braking to maneuver at slow speeds when the tail feathers aren't doing much of anything.

I have spent a great deal of time converting Geoff Resney's CLT Air Command Tandem from a 130HP, 325 lbs. Subaru that used a belt drive, CCW prop, to a 160HP, 170 lbs. Yamaha with a gearbox, CW prop. Airframe has had to be changed, including cheek plates, push tube adjustments, trim springs, and rudder controls, and it all has to be tested and tuned up.

It is a full 2" higher than my own CLT Air Command Tandem measured at the rear seat. Mine uses the original Fetters' soft-coupled nose wheel with directional springs on the pedal attachments. This one has cables connecting the NW directly to the pedals & rudder with ZERO play, no forgiveness at all. On top of that, it had a monstrous spring to be overcome with a LOT of pedal pressure just to turn the rudder or wheel even 1° or 2°. It did nothing except fight you every time you wanted to turn. "Why would anyone make it HARDER to turn", I thought to myself? I took it off before the engine was installed.

I tried to balance on the mains to get a feel for the machine even before I changed the rudder push-pull cable attachments, which were askew more than 1" at the keel attach points - to tune the rudder to the original CCW prop wash. I thought, "What the hey, it's just a little pedal, I can work with it while just balancing on the mains, right?"

No way. In dead calm winds, just barely lifting the nose, the tail went left, the nose went right, the gyro started veering off the taxiway, and as I let the nose come back down it jerked hard. I tried it over and over again, and no matter what I did that damn hard-coupled nose wheel jerked me around when it touched down. That stiff, short, self-centering spring made no difference since you still have to turn the rudder to correct directional travel when the nose lifts, and that is still going to be pointing the wheel away from the direction of travel regardless of having a centering spring or not. That darn thing just made it harder to push the pedals, is all the good it did.

I thought, "How the heck am I ever going to tune it up if rolls over before I get it right?"

I disco'ed the nosewheel cables, and voila. A smo-o-o-o-th, predictable, and enjoyable tuning lay ahead of me from that moment on.

Screw it. I am weighing in on this discussion.

On a HIGH COG gyrocopter you do NOT want a hard coupled nose wheel which has zero forgiveness!!! DO NOT DO THIS!

It really doesn't matter how many successful landings you may have under your belt in a high COG gyro which has a HARD-coupled nose wheel, it is still a TERRIBLE DESIGN that one day can very easily be the root cause of a very bad day. Why make things harder to deal with when you can make them easy to be safe in the first place?

As to the ORIGINAL QUESTION for this thread: The type of gyro air frame has a LOT to do with the CORRECT choice of nose wheel, suspension and the way it steers.

I simply do not understand why certain gyro designers and builders make things harder to control, when making them smooth, and easy, is what they should be most concerned with. It is nice that some guys can deal with anything, that they've never had a rollover, that they consider themselves experts in good design as a result. But the reality is this: The true experts and the excellent pilots are few and far between. A gyro needs to be built for the WORST pilots, not the best.

In closing:

(1.) A low COG gyro can tolerate a hard-coupled, steering nose wheel far better than a CLT, or higher COG gyro can.

(2.) A soft-coupled steering nose wheel is ALWAYS far better than a hard-coupled nose wheel, if you must go with a steering nose wheel.

(3.) A Short wheel base (All Eurotubs) should NEVER be hard-coupled! Soft coupling might help, but shortening the wheelbase does as much if not more to increase rollover incidents as does high COG.

(4.) Never use a hard-coupled nose wheel on a high COG, CLT, or HTL gyro air frame.

(5.) Avoid using soft-coupled nose wheels on high COG, CLT, and HTL gyro air frames, unless the forks are raked forward like a motorcycle.
 
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I always get a bit skeptical when I see/hear "never", "always", and "all", especially in capital letters.
 
Eurotub designers apparently don’t understand the solutions to power/yaw coupling and power/torque roll provided by Cierva in the 1930s.
Take a look at any Cierva Autogiro from the 1930s and observe the ratio between dorsal fin and belly fin; this serves to eliminate yaw by producing equal and opposite effects as a result of propeller slipstream rotation. The dorsal fin is blown one way by the rotating slipstream and the belly fin is blown the other way an equal amount for a net zero.
The horizontal stabilizer of Cierva Autogiros is centered in the propeller slipstream and has differential pitch settings to eliminate power/torque roll.
Vance’s Blunderbeast is a partial copy of a Dominator; the tall tail eliminating power/yaw coupling and providing some reduction of power/torque roll.
Therefore Vance doesn’t have to go through the usual rudder pedal toe dance during takeoffs and landings required by Eurotubs.
 
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I always get a bit skeptical when I see/hear "never", "always", and "all", especially in capital letters.

THANKS! Oops. Capital letters. My bad.
 
Jeez, I am such an idiot.

Yep, first to admit that.

I forgot about high-speed castoring wheel wobble. Dangit.

Yeah, I was able to taxi around my hanger area just fine. But when I got it out on the taxiway it was as bad as a Walmart shopping cart.

Spun up the electric pre-rotor all it would go - barely 100 RRPMs (it could probably do better with a brand new battery, although this one tests out to be just fine for a used one) - and just enough so I could start rolling, and as soon as I got it to go fast enough to add a meager 8 more RRPM the nose wheel wobbled and shook so bad I thought the pod would come off.

I have witnessed similar nose wheel wobble on Dominators at Mentone, and the pilots complained when I brought up how unsafe this must be that they can't feel a thing and it does NOT affect the ground handling of the aircraft. They further pointed out that FW with free-castoring nosewheels sometimes do this and they are not dangerous at all, so how can a high COG Dominator be at danger? Oh, well. I am quite often misguided, arrogant, irrascible, wrong, over-extended, and totally stupid.

Well, this one on the Doug Smith designed Air Command yesterday is not designed as well as Ernie's, and I could DEFINITELY (oops, capital letters. Guess emphasis is never needed when writing. Ya'll understand me perfectly w/o caps, and can hear my exclamations regardless. But how do I convey my eyebrows raising? or an inflection of my voice without making ya'll suspicious of CAPITAL letters? Italics? hell with that, it is extra keystrokes to change the font, and why should I bother?) tell you IT WAS DANGEROUS!

Returned to the hanger, re-connected the hard-coupled nose wheel and adjusted the cables so it pointed straight ahead with the tail straight. Seemed to be OK when I took it back out to test it again, but it is not fun to operate - for me, at least. woudl like to install springs on each cable connector to soften the alignment problems when the nose wheel and rudder do not align perfectly with the direction of GROUND travel as the nose touches down.
That's a project for another time, perhaps. I really need to be able to balance on the mains for a few thousand feet w/o letting the tail or nose touch, then I need to get her in the air to see how the stick goes.

Baby steps.
 
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To the 3 people who are actually interested in what I am doing and who are active on Rotaryforum.com, let me just say that when you use mayonnaise, you do NOT use ketchup, and when you use ketchup you do NOT use mayonnaise. Jeez.
 
Did I ever mention I recorded 680 lbs of thrust and still had another 1000 ERPM left on the tach? Yeah, that too. We bad. That's 680 lbs of thrust with a STOCK, NORMALLY ASPIRATED engine that only weighs 170 lbs all-up, installed. THAT'S the incredible part, pilgrim - fkg CAPS, bad attitude, and all.
 
To the 3 people who are actually interested in what I am doing and who are active on Rotaryforum.com, let me just say that when you use mayonnaise, you do NOT use ketchup, and when you use ketchup you do NOT use mayonnaise. Jeez.
I guess you never heard of "russian" dressing. It's big in New York
 
You get both mayo and ketchup on a whopper.
 
Then there are folks like me who prefer salad dressing over mayonnaise as a condiment. To which ketchup also tastes good with!

Jim Vanek's nose wheel assembly on his Sport Copter machines achieves zero nose wheel wobble through the use of two large delrin-type discs w/ dielectric grease as a medium. He told me he tested it towing behind a vehicle up to 80 mph, w/out any wobble.

I found his claim of zero wobbling to be 100% truth, although I never took my SC gyro up those speeds while on the ground. After adding a slightly heavier Yamaha engine for more HP, my takeoff AS is about 47 mph. Zero wobble. Tracks like our vehicles do (car or motorcycle), plus has shock absorbency built into it.
 
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