Landing gear unique to Gyroplanes in contrast to fixed wing aircraft

[Rowdyflyer1903!]

Your observation are correct. Typically the nose gear is incorporated with the engine mount and all of those forces radiate back to the firewall who must distribute the forces throughout the fuselage evenly. Under the main gear is oddly named a “gear box.” It has no gears but more or less a truss box which job is to disburse those landing forces which the spring gear imparts from the lack of finesse of the student pilot.

The main wing gets a lot of help from the elevator and a long moment arm to rotate and lift the nose up to the wings sweet spot angle of attack for climb out and or flare for landing. In flight a fixed wings tail has as much as 10% of the aircrafts total weight to deal with to keep the wing from pitching down or up depending on area of pressure travel vs angle of attack. A gyros horizontal surfaces has an easy but necessary job ( with some debate) especially at higher velocity. In fact we want that surface very neutral in lift. I have never seen a modern gyro with an elevator or a trim system on the horizontal surface. No need to complicate for little gain.

The gyro nose gear gets a bit of a pass as our main gear bears 90% of the load of the beast. It is fun to watch spot landing contest and wonder with amazement why gear doesn’t bend. What Carter Copter, Jay and David did with the butterfly landing gear system is outstandingly impressive but it is a butt ugly gainly looking beast. If I owned one I would think it was beautiful.

 

[Doug Riley]

... Just getting back to this thread.

I've flown a former student's Butterfly, with G-force gear, a number of times. IMHO, it's a step in the right direction, but not a finished design.

The Cierva-era autogiros could land right in vertical descent. We in sport-gyro-land still struggle to duplicate the performance of this 90-year-old technology. It's kind of embarrassing.

The goal of landing gear is to spread out the deceleration of the aircraft over time. This translates into a long gear stroke with some form of friction applied continually during the compression of the gear. The friction converts the kinetic energy of the descending aircraft into heat, which is then dissipated in the surrounding air. Same principle as conventional car brakes.

Ideally, the wheels should move straight up during this process. Where many of us have gone wrong is in trying to simplify the gear by using swing axles. It's tempting to do this because the basic Bensen-style frame is 2-dimensional, like a bicycle. We adopt center-mounted pivots for our axles because...a Bensen frame doesn't have SIDES. "Center" is all there is.

But swing axles, in the long gear stroke we need, produce large lateral movements of the wheels. This leads to the infamous Dominator "duck walk" and related problems. The Butterfly G-force gear still relies on swing axles.

The way to go is simply to copy an old Cierva/Pitcairn. You'll need a minimum of five struts sticking out laterally on each side (sorry). None of these struts will pivot at all; they form a fixed truss that supports telescoping, vertical up-and-down legs. The friction device is built into these legs. You need a stroke of 2 feet or more to keep the G's down to a reasonable figure coming out of an established vertical descent.

And -- sorry again -- you'll need a third such compressible leg for the nosewheel. One scary aspect of my friend's Butterfly is that the nose gear is not long-stroke to match the mains. When you touch down with the mains extended, the nosewheel is a mile off the deck. There's some risk of a forward capsize unless you hold the stick back while the gear is compressing. But then that's an invitation to a crosswind tip-over.

For this reason, my friend normally disables his G-Force gear by locking it up in the compressed position. It's easy to set a gyro down softly using normal stick techniques. With the gear pre-compressed, you are free to shove the stick forward INSTANTLY upon touchdown -- which is the only safe thing to do in a breeze. The long-stroke gear is useful mostly either for showing off or for making emergency landings in rough country (where you won't be flying out again).

 

[Tyger]

The Cierva-era autogiros could land right in vertical descent. We in sport-gyro-land still struggle to duplicate the performance of this 90-year-old technology. It's kind of embarrassing....
The long-stroke gear is useful mostly either for showing off or for making emergency landings in rough country (where you won't be flying out again).

My impression of the films of those old-style near-vertical gyro landings is that they were doing exactly what you say: just showing off for PR.
The limited practical use of such landing gear would not seem to compensate for all the extra weight/drag/complexity.

 

[Doug Riley]

My Butterfly-owning friend thought that the G-Force was worthwhile for flying over unfriendly country, and perhaps for making the gyro more forgiving of beginner landing mistakes. Because of the need to hold back stick during the compression of the gear, though, I have to disagree on the latter point.

Wide, long-stroke outrigger landing gear, with huge wheels, was common on 1930's aircraft, not just autogiros. Cow-pasture flying was pretty routine then.

Really good long-stroke gear, combined with jump takeoff, might allows us to dispense with runways. That really would add to the gyro's abilities -- though, as Tyger says, at considerable cost+complexity+weight.

 

[Vance]

I recently emailed a photograph to a fellow pilot depicting a solution to my nose gear, a problem created by raising the forward portion of my Parsons based fuselage to more align the CG to thrust line. After much thought, or so I had convinced myself, I chose a caster style design, similar to a Grumman Yankee.

I had several goals in mind. First I wanted something more sturdy than some of the single strut nose gear found on several of the Center Line Thrust Configured builds. I felt that th machine would be confined to paved runways. Notably during take off roll prior to the nose lifting, operations on a grass strip, felt would be risky, if sand, soft spot, golpher or fireant mound might be encountered. A non braced support of the nose wheel will not resist folding and thus becoming a yard dart with a major wallet hurt soon to follow.

I also have chosen hydraulic toe brakes as my method of steering. I am experienced with caster nose gear plus in a formal life also an experienced taildragger pilot ( If 500 hours is enough tailwheel time ) I also intend to install a shock but, at this point of the build, what weight which will be born by the nose is uncertain. Because of this a fabricated piece of stream lined 4130 chromoly extrusion was installed.

My pilot friend replied and ask if my nose gear was suspended. I replied no not at the moment but most Parsons and other similar un modified designs we not suspended either. Understand, I first saw this person fly in 1982, give or take a year. I hold this person in high regard.

His silence was deafening.

Sometimes that is all it takes for a would be designer/ modifier to meditate a bit more. Of course the more you think about things, more questions than answers arise.

Back to the subject of my post, Gyroplane landing gear is very much different in its roll or transitioning from something which rolls to something which flys and hopefully back again.

One poster, I read stated that the design differs in the fact the main gear supports much more of the total amount weight than fixed wing. Consensus here had the percentage between 10 and as high as 18. Users results may vary.

We also discussed how much rocker is needed to rotate ( kind of) to allow the fuselage to get out of the way of the rotor as it seeks that sweet spot where she wants to fly. ( This was stated this way because if the configuration is wrong our own version of mast bumping aft can occur at the rotor head )

The hang test helps us with this problem as adjustments can be made to center the stick to assure the rotor, in her little world, can live her life semi independently of the fuselage, which should follow her through the air without complaint.

We dangle beneath the rotor with a wiggly u-joint of sorts. Everyone knows this. In the air, the offset gamble and tower mounted under slung semi ridged teetering rotor system is nothing short of genius. In the air the rotor does what it needs to do and the fuselage partners with her in harmony. All is good eh?

Not on the ground it isn’t.

If you have ever seen or better yet experienced a rough field take off, the stick can be very violent in your hand. All you can do is grip the stick firm enough but understand to allow the movement. What you are witnessing is difficulties in this early marriage of rolling vs trying to fly because the more immature of the partnership is now playing on a seesaw under the rotor because of uneven ground.

The stick moves back and forth and every bump the nose gear strikes rockets back to the mains and the wild ride begins. We are fortunate this last only until the airspeed increases and the nose wheel rotates free and clear where the bumps now are up and down. You still have to be aware of the bumps one of the main wheels may experience adding to the fun. Maybe the rudder is alive at that point because if not and you don’t have toe brakes to differential steer and you are now at some crazy angle, its time to pull power and get the nose wheel back down for control.

Whewwww, cheated death one more time.

A smooth runway sure makes being a gyro-naught a lot easier. No argument. Especially when the only suspension available is the cushion from air in the tires to smooth your departure and landing experience.

Can we all appreciate Steve McGowen a bit more? Let’s give that shirtless veteran of the military and the air a big hand of applause of appreciation of his skill and dedication to all of us.

GAWD ROWDY WHERE ARE YOU GOING WITH ALL THIS!
Make your point!

Ok, whether or not your main gear is suspended, if you can spring mount or shock mount or coil over your nose gear to tame the seesawing motion in the beginning of your take off roll before the nose comes up and you lightly place it back down to balance on the mains as all worthy gyroplane pilots have done who has come this way before us.

Oh and when you do get airborne don’t get stupid. All that gyration will soon dampen. Don’t chase it. Lower the nose, build your airspeed, climb out, keep your eye peeled for the emergency landing spot and go enjoy your time in the sky.

The end.

I feel you may be over thinking it.

You are correct that there is no reason to design something stronger than your frame.

Because of your free castering nose wheel there is not likely to be much side loading on your nose gear.

Assuming a reasonably competent pilot; I feel two inches of travel would be plenty.

As much as four would be make landing and the transition to balancing easier.

The Predator was rigid until I started training and clients started bending the nose gear.

It seems for many; slamming the nose into the runway on landing is a part of the learning process.

What I have now is a two day effort with whatever was laying around the shop.

If I were to do it over again the lower suspension part that is between the wheel and the pivot would be steel tubing instead of aluminum plate.

She has around two inches of suspension travel.

As a motorcycle enthusiast I am familiar with girder front ends like on Indians and Vincent motorcycles.

I have built several for different projects.

The one picture is from my Sportster and I used streamlined tubing for the legs and the other is an Indian Girder fork.

To make a free castering nose wheel work you will need trail and how much is always a guess.

The Predator uses about three inches with no rake and that seems to work, some other dimensions might be better; again it was just a hurried guess.

Putting the steering head at the top makes a steering dampener easier but limits how far the wheel can turn.

Putting the pivot at the bottom allows the wheel to turn 360 degrees, a feature I like and dampening can be done several ways.

On The Predator I have a circular surface (around four inches) with a plastic disk sandwiched between two steel disks using dielectric grease for the dampening means and this seems to work just fine.

Old Triumph motorcycles captured a friction disk and adjusted it with a screw and a spring. They intentionally had a little slop in it to deal with overcoming static friction. This system could also be used and is adjustable.

On Mariah Gale we used a single Cessna wing strut with the pivot and dampening contained in the leg with multiple friction elements adjusted with Belleville washers.

We had two links at the top for suspension like a girder front end but outside of the Cessna strut.

She never flew so I don’t know if it would have worked.

It was light, clean and aerodynamic.

 

[Rowdyflyer1903!]

My Butterfly-owning friend thought that the G-Force was worthwhile for flying over unfriendly country, and perhaps for making the gyro more forgiving of beginner landing mistakes. Because of the need to hold back stick during the compression of the gear, though, I have to disagree on the latter point.

Wide, long-stroke outrigger landing gear, with huge wheels, was common on 1930's aircraft, not just autogiros. Cow-pasture flying was pretty routine then.

Really good long-stroke gear, combined with jump takeoff, might allows us to dispense with runways. That really would add to the gyro's abilities -- though, as Tyger says, at considerable cost+complexity+weight.

Ron Herron’s Little Wing has an interesting main gear design. I asked him about it and he replied he liked the looks and was trying to capture the older style mechanism. I personally love the look of the Little Wing 2. Woodstock is a beautiful bird. i have to admit being smitten with his design. Years ago I bought a set of plans, lost them and bought a second set. If I live long enough maybe…….