S-turns

[EdL]

Sorry, WaspAir - got distracted yesterday and handled some of these out of sequence. I'm sure you've been waiting for my reply :biggrin:

No, you're apparently picturing a long skewed final approach over houses and hangars that nobody here is advocating. The diagonal path limits only the on-pavement rolling to 120 feet and then only if you don't have any taxiways to aim for, but even so that's not quite the same thing as having a tiny airport with only a 120 foot runway. You still have a broad open area of airport over which to do all your approaching and descending. You can fly your final in full coordination with a wind correction angle in your heading (I hate the term crab, because it improperly suggests uncoordinated yawing to many) just on the downwind side, until lined up for your touchdown path, when you adjust slightly to point parallel to the windsock and put it down with very, very little groundspeed and no need for more rolling distance (and certainly no risk to houses and hangars). If the wind is significant enough to require that correction, you can have a truly small ground speed, and you will find that 120 feet is a pretty big target, while the hangars look very distant at that slow rate of closure.

There may be a perception problem here from never having seen it done, and from the specific aircraft you fly and touchdown speeds with which you are accustomed, which may be why you consider this to be a non-standard dirt-bike sort of operation. .

OK - as described, that doesn't sound too outrageous - and also sounds like it's only possible as described for relatively small amounts of demonstrated crosswind. And there's a difference between a 20kt wind from 30 degrees off the runway and 10 kt from 90 degrees: both give a demonstrated crosswind component of 10kts but turning 30 degrees into the first makes it pure headwind while turning 30 degrees into the 90 degree one still gives you most of that 10kts to still deal with, so one still needs to manage that, and now on a shorter effective runway because of the turn.

From my perspective, using the slip technique instead is the cowboy maneuver, needlessly risking control loss, runway excursions, rollovers, and such.

Actually, I'd hardly call the procedure published in the FAA's handbook, as cited by Vance, the "cowboy maneuver". And again, unless one is truly able to point directly into the wind, one still must deal with a crosswind - by the "cowboy maneuver".

Personally, I find a 25 kt. demonstrated crosswind component to be nothing short of silly for a gyroplane. If the wind is that strong, I can always land with zero roll by just pointing into it. Nobody will care about your orientation to the pavement if you're not moving on it, and you won't be thought a madman for using minimal runway.

First, remember that's the design limit of the gyro - not the proficiency of the pilot. Second, while I'm not sure I've actually landed in 25kts of demonstrated crosswind, I can definitely say there have been days where I've looked at the windsock out my window and said there's no way I'd take my Warrior up but have gone up with the gyro with no problem at all. We have houses on the west side, so winds from the west give us some un-cool burbles right when you get to the runway, which is always sporting in the Warrior. By contrast, I was surprised at how little they're felt in the Magni, even when "air taxiing"/"landing long" for 2000 feet of the runway at 2-3 feet off the deck and 65mph. And, once again, with your technique you're either still needing to slip or you're turning up to 90 degrees to the runway.

Incidentally, take a look on Google Maps at Lakeway Airpark and see if you'd be comfortable landing 90 degrees on a "taxiway". Maybe so, but the locals would ensure it only happened once...

As to the “crabbing” comment, crabbing is an integral part of flying for every airman except balloonists. It’s a lot quicker to say than “wind correction angle” and is a concept to be understood and mastered through all phases of flight - takeoff roll to touchdown. “Remember how we had to crab to get our ground track out to the practice area to be what we wanted? And remember how we compensated for wind during S-turns? It’s the same issue here in the pattern”.

One other thing: I do keep an approach speed as close to 65mph as possible pretty much for every landing (as per the Magni book). Touchdown speed is indeed much, much less (as close to zero as practical). Two big reasons: first, the more air over the rudder, the more rudder authority one has. Second, a go-around at 65 is a non-event; a go-around at 20mph is scary at best and often not possible. One is progressively reducing options as one goes from 65 to 20. Also, I most definitely keep my approach speed up when it's gusty; inertia is your friend in those cases.

/Ed

 

[EdL]

The "big players" clearly understand rake, trail, and offset design in lieu of using the same design of a grocery cart wheel. Properly designed, either geometry will perform quite well. I'm sure Vance can chime in on the geometry of vehicles with a forward rake front wheel. I guess the owners of millions of motorcycles, bicycles, trikes, and countless other vehicles with a single front wheel are not smart enough to demand a rearward leaning front wheel. (roll eyes)

...but have you ever tried pushing a grocery cart backwards - fast?:wink:

Try doing a “wheelie” with a grocery cart and let it get a bit sideways then put the front wheels down. No biggie. Turn it around and do the same thing with the fixed wheels in the air. It darts to one side. That’s what seems to happen with gyros with rake (thanks for reminding me of the term).

I’m not convinced manufacturers do it as a cost-saving measure - possibly. I suspect they do it to increase the wheelbase, which has its own positives. But by comparison, whereas the turning arm for the handlebars on a motorcycle or bike is maybe 2 feet, it’s less than a foot for the rudder pedals: much less leverage to overcome the desire to dart to one side when the wheel hits the ground at speed and an angle (and how often does that happen in a “regular” motorcycle or bike? And I’m not an expert but I’m not sure I’ve seen a lot of Motocross bikes with a good amount of positive rake).

But for me personally the accident reports and anecdotes for gyros were just too telling. Way more departures from the pavement on landing for Autogyros and ELAs, in my opinion, than for Magnis. Too few AR-1s and TAGs out there to be as statistically powerful yet but I suspect time will substantiate this for them too. And I know it’s at least partially a “training issue” but at my age and with my short attention span, I just like reducing the variables as much as I can...

/Ed

 

[Vance]

A quick explanation of rake and trail and in my opinion how it affects motorcycles and steering a tricycle.

Trail is the distance from an imaginary line drawn through the steering head (pivot) to the ground and measured back the center of the contact patch.

A steering head with rake and no apparent offset will still have trail and self-centering torque.

Rake is the angle of the steering head compared to vertical.

In most general terms trail is responsible for making the wheel point in the direction of travel and rake dampens trail. More rake makes for slower steering and more trail makes for heavier steering.

At Bonneville most people with custom frames use lots of rake (36 degrees) to keep the wobble down at high speeds and lots of trail (five plus inches). On my 200 mile per hour Sportster I use 26 degrees and three inches of trail because I have narrow handle bars and need light steering to make it work. I have girder suspension with leading links. With no steering dampener it shook its head a little at around 190 miles per hour. It has very light steering at all speeds. Design is a compromise.

Often there is some additional friction or dampening to further dampen the natural dampening from the rake. I have an adjustable hydraulic dampener on the Sportster.

Most motorcycles have between 24 degrees of rake and 36 degrees of rake and between three and a half and five and a half inches of trail.

Too much rake doesn't work well on a tricycle because it lowers the nose on either side of center.

My experience with AutoGyro products is that they have considerable trail and self-center just fine as long as you are not too heavy on the pedals.

I have not had one develop a shimmy on takeoff or landing.

All design is a compromise and AutoGyro has decided to compromise on the side of light steering forces and not needing much dampening.

The Predator has no rake and about three and half inches of trail. The first one we built had closer to four and a half inches of trail and did not steer as easily with differential braking and was more prone to shimmy.

The Predator uses a plastic disk with dielectric grease for dampening something like a Sport Copter.

Tim learned to land in the Predator and as far as I know is having no trouble adapting to his MTO Sport.

There are lots of landings happening with AutoGyro products with no problems.

Steering geometry cannot fix stupid pilot tricks.

Trailing or leading link is a kind of suspension and is unrelated to steering geometry.

The Predator uses trailing link front suspension. We could have built any amount of trail into the system; we chose three and a half inches with no rake.

The Magnis, Titanium Explorers and American Rangers I have flown all have very heavy steering and are sensitive to low tire pressure.

Design is a compromise.

 

[EdL]

Thanks, Vance - I clearly have/had a lot to learn. Appreciate the explanation.

/Ed

 

[Vance]

My pleasure Ed.

I appreciate your input on this thread.

It helps me to become a better instructor.

Steering geometry is a complex subject and it is hard to know where to stop with the explanations.

I have spent a lifetime learning about suspension, geometry, frames and load paths for motorcycles.

It frustrates me than gyroplane suspension is so primitive.

It made a world of difference to my clients when I added front suspension to The Predator.

It would be fun to experiment with more sophisticated suspension and dampening on a gyroplane.

As I learned more about how to land it made less difference and became unimportant.

I would still like to do a ground proximity sensor to let me know when it is time to flare.

I experimented with a back up alarm from a car and it worked great.

Again as I got better at landing it became less of a priority.

 

[WaspAir]

Hi, Ed -

I think we are much closer to understanding each other, regardless of whether we agree, so I will limit myself to two topics. First, for a little zephyr of wind, I don't worry about it. But if the crosswind component is enough to get my attention, I will land into the wind, no matter what angle that requires. Because I habitually land as slowly as possible, it isn't a problem to do it. Landing slowly enables landing in very small distances across pavement, especially as wind increases. If you must land fast because of aircraft design issues, the room required may determine your technique, but the aircraft I fly don't suffer from that.

Next, I'll address this:

As to the “crabbing” comment, crabbing is an integral part of flying for every airman except balloonists. It’s a lot quicker to say than “wind correction angle” and is a concept to be understood and mastered through all phases of flight - takeoff roll to touchdown. “Remember how we had to crab to get our ground track out to the practice area to be what we wanted? And remember how we compensated for wind during S-turns? It’s the same issue here in the pattern”.

I have no issue with doing a "crab" (I suggested it above), but I have a big issue with the term for it.

As an instructor, I have to deal with the perceptions and (mis-)understanding of students, and to them, a crab is an animal that habitually and intentionally walks sideways. It is not walking forward on the sand and getting drifted by ocean currents, it is propelling itself at an extreme angle to its longitudinal axis. If an undersea crab had a yaw string, the string would be pointed completely out to the side while it walks. It is an uncoordinated way of getting around.

As a matter of pedagogy (and as an instructor, that's a primary concern for me), the term "crab" is a horrible choice in aviation. An aircraft properly doing a "crab" sees airflow directly along its longitudinal access. It is propelling itself forward along that axis. The reason its ground track doesn't match is only because of the drifting effect of wind. All the while It is done in coordination, with the yaw string straight back. An aircraft moves like a salmon, always swimming forward (sometimes into currents), and not at all like a crab,.

Students (and this includes experienced pilots) that I have encountered do not always understand this distinction. Back when I still used the term "crab", I found that when I suggested it, a too-common response from the student was to enter a skid. Many, many people will add rudder to produce an angle, rather than make a coordinated turn to hold the new heading in coordinated flight, drifting to the desired ground track. I think the term crab contributes to this issue, and I try very hard to avoid using it unless the subject is seafood. Instructors have an obligation to communicate and reinforce concepts clearly, and that word hurts the effort in this instructor's opinion.

[This shows up far more often than you might think, with people from whom you would not expect it, and sometimes it even accompanies a huge conceptual error. For example, a few years ago, an AOPA article described test flying a new LSA, and the author described how easy it was to hold rudder against a crosswind while on a cross-country leg. I wrote a snarky letter to the editor suggesting how much easier it would have been to fly in coordination with a heading correction, but they did not respond.]

Part of the problem may be that this "crab" label suggests to some that it is a maneuver to be learned, such as slipping, slow flight, stalling, etc., that is a particular kind of deviation from ordinary flight rather than just flying with the controls in perfectly normal position.

Fortunately, there are other standard aviation terms that will suffice without those conceptual pitfalls. When one teaches cross-country flight planning, it is customary to use an E-6B (or equivalent) with forecast winds to anticipate the wind correction angle that will be needed for your heading to yield the desired course. In flight, one can discuss what must be done to correct for wind drift one encounters, and it is always to change the heading. Choosing the proper angle is a basic airmanship task, but it is an angle adjustment, not a maneuver in itself. It is exactly the same thing in the pattern.

I find it interesting that many instructors I know use the term crab only in the pattern and not in cross-country flight, and that difference is not helpful conceptually. Did your instructors have you "crab" for 50 miles at a time? Perhaps so, but many only pull out this word on downwind, as if it is something different, and that's not helpful.

I want my students to think like this:
How should one correct for wind drift, in any phase of flight? Simply turn a bit into the wind, and continue to fly in a coordinated fashion.

I find that students get that idea, and retain that idea, better if the term "crab" is left out of the discussion. As an instructor, it is my obligation to do all that I can to instill ideas that will carry forward long after they have left the training environment. I have no doubt that you understand these things perfectly well, but I am trying to increase the odds for everybody else to achieve that as well.

 

[EdL]

Thanks, WaspAir - makes sense re the “crabbing” term. These days, with GPS, I imagine there’s considerably less awareness of one’s heading vs their ground track. I know for me, my mag compass is utterly useless so I (have to) go entirely by GPS ground track.

/Ed

 

[Vance]

No Title

I like using the vertical card compass in The Predator and it is a part of the practical test standards (plus or minus ten degrees).

It helps me to understand which runway is which before I get to an airport and can read the numbers with two or three runways.

I feel wind correction angle is an important part of flight planning although the winds aloft are seldom correct. I feel a chart and a watch are important elements of dead reckoning.

They do a lot of GPS interference testing around here and I would be lost if I depended on a GPS for navigation.

That is my compass correction card there on the left. We spin her every hundred hours.

Uncoordinated flight in The Predator makes her less efficient.

I teach people to fly coordinated except when landing.

She sinks noticeably faster the more uncoordinated she is flown.

 

[EdL]

Oh, I like VCCs too and use one every time in my Warrior to align the DG and cross-check it during IFR flights. Magni has a problem with compasses in the M-16 and my VCC in it is laughably inaccurate. Probably because the panel is so small and radios, etc. interfere with it or something. On the M-24 it’s pedestal-mounted and accurate. I just gave up on the M-16 and, in hindsight, wish I had known that and stuck with the much cheaper whiskey compass. Fortunately the gyro is day VFR and the GPS around us has been accurate.

/Ed

 

[Kolibri]

The Magnis, Titanium Explorers and American Rangers I have flown all have very heavy steering and are sensitive to low tire pressure.

The free-castering Sport Copters I have flown do not have heavy steering at all, and will easily turn 360s within their own wheelbase.
They do not shimmy, either.

All design is a compromise and AutoGyro has decided to compromise on the side of light steering forces and not needing much dampening.

Here is the nosewheel of the MTOfree and an ELA.





Thus, I stand by my assertion:

The AutoGyro and ELA "big players" find it easier to mfg. a cheap nosewheel fork, and their customers generally don't know to demand anything better or safer.

Regards,
Kolibri

 

[EdL]

Yes, your images seem to substantiate what Vance and High Altitude pointed out and it does appear the MTO has less trail than the ELA, though both have some.

Can you substantiate the "cheap nosewheel fork" comment or is that just a seemingly libelous personal opinion?

 

[Kolibri]

My experience with AutoGyro products is that they have considerable trail and self-center just fine as long as you are not too heavy on the pedals.

Mild self-centering is not equal of free-castering (if properly dampened to prevent shimmy).
And the "not too heavy on the pedals" is an unnecessary half-measure for a trailing-link free-castering NW gyro.


__________

Can you substantiate the "cheap nosewheel fork" comment . . . ?

Show me a cheaper, yet functional, gyro fork design.
Show me a cheaper material that is still sufficiently robust for the part.
I'll wait . . .

Regards,
Kolibri

 

[Vance]

The free-castering Sport Copters I have flown do not have heavy steering at all, and will easily turn 360s within their own wheelbase.
They do not shimmy, either.


Here is the nosewheel of the MTOfree and an ELA.





Thus, I stand by my assertion:



Regards,
Kolibri

This is a good example of why I don’t try to educate Kolibri.

I never said the Sport Copter had heavy steering, shimmies or would not turn around in its own length and if he had read and understood what I wrote he would know that like The Predator the Sport Copter has a plastic disk to dampen the tendency for the nose wheel to shimmy and like The Predator the Sport Copter has a free castering nose wheel and is steered with differential braking. Trail is required to make a free castering nose wheel work.

My preference is a free castering nose wheel with differential braking. Some of my clients prefer a linked nose wheel.

Tim is a good example of an informed, sophisticated AutoGyro customer. He understood all of this as an engineer and as client we had discussed it at length. He flew all of the available tandem kits and we discussed the design compromises of each. Tim chose the MTO Sport.

To say that AutoGyro customers don't know to demand something better or safer is insulting to them and typical of a person with limited experience and understanding who is more interested in insulting people than learning.

It has not occurred to Kolibri to write that he can see he was wrong about AutoGyro and ELA not having trail.

In my opinion the RAF 2000 Kolibri flies has the worst ground handling of any gyroplane model I have flown. There has been a remarkable number of ground handling accidents in RAF 2000s. He still doesn't know enough to make fixing the rigid landing gear and the ground handling on his aircraft a priority and is content to pass this safety challenge on to the next owner.

 

[EdL]

Sometimes it seems difficult to tell if a troll is a fool or a knave. Kinda moot: still a troll, not adding value.

/Ed

 

[Kolibri]

I never said the Sport Copter had heavy steering, shimmies or would not turn around in its own length

Vance, I never said that you had.

. . . he would know that like The Predator the Sport Copter has a plastic disk to dampen the tendency for the nose wheel to shimmy
and like The Predator the Sport Copter has a free castering nose wheel and is steered with differential braking.

Which gyro had all that before the other?
Shouldn't you rephrase to be accurate and fair to Jim Vanek: "like the Sport Copter The Predator has . . . "

It has not occurred to Kolibri to write that he can see he was wrong about AutoGyro and ELA not having trail.

You're right, it hadn't occurred to me . . . because I didn't claim that.
They don't have a free-castering trailing-link NW.

To say that AutoGyro customers don't know to demand something better or safer is insulting to them and typical of a person with limited experience and understanding who is more interested in insulting people than learning.

You're forgetting my qualifier "generally" and turning into a personal insult of Tim, which was not my intention.
If they generally did "know to demand anything better or safe" then AutoGyro would have no choice but to provide it.

In my opinion the RAF 2000 Kolibri flies has the worst ground handling of any gyroplane model I have flown. There has been a remarkable number of ground handling accidents in RAF 2000s.

I agree. But, as with other gyro pilots and their machines' particular issues, I became sufficiently proficient to handle it.

He still doesn't know enough to make fixing the rigid landing gear and the ground handling on his aircraft a priority and is content to pass this safety challenge on to the next owner.

It's odd how you never chastised RAF or RAFSA for their own poor design.
Or that you never rebuked CFI/broker Dofin Fritts who was shamefully "content to pass this safety challenge on to the next owner" when I bought it.

I looked into what it would take to rectify the landing gear (Sport Copter had done so once), and the nosewheel mod is extensive.
I've sunk plenty of money into my RAF, and learned a lot. It's a manifestly better and safer RAF than what I purchased.
I'll recommend to potential buyers what remains to upgrade (e.g., the landing gear).
As you say, many RAF owners have learned to fly that gyro without mishap.

Regards,
Kolibri

 

[Vance]

No Title

Vance, I never said that you had.


Which gyro had all that before the other?
Shouldn't you rephrase to be accurate and fair to Jim Vanek: "like the Sport Copter The Predator has . . . "



You're right, it hadn't occurred to me . . . because I didn't claim that.
They don't have a free-castering trailing-link NW.


You're forgetting my qualifier "generally" and turning into a personal insult of Tim, which was not my intention.
If they generally did "know to demand anything better or safe" then AutoGyro would have no choice but to provide it.


I agree. But, as with other gyro pilots and their machines' particular issues, I became sufficiently proficient to handle it.


It's odd how you never chastised RAF or RAFSA for their own poor design.
Or that you never rebuked CFI/broker Dofin Fritts who was shamefully "content to pass this safety challenge on to the next owner" when I bought it.

I looked into what it would take to rectify the landing gear (Sport Copter had done so once), and the nosewheel mod is extensive.
I've sunk plenty of money into my RAF, and learned a lot. It's a manifestly better and safer RAF than what I purchased.
I'll recommend to potential buyers what remains to upgrade (e.g., the landing gear).
As you say, many RAF owners have learned to fly that gyro without mishap.

Regards,
Kolibri

I stand corrected Kolibri Ed was the one who felt there was no trail on the AutoGyro and ELA products.

Your confusion is more narrowly focused.

Sport Copter did not invent free castering nose wheels or trailing link suspension.

Mark Givans did not copy Sport Copters free castering nose wheel.

Smokey Aleman designed and built the trailing link nose gear on The Predator and had never seen a Sport Copter. The design is different and was in a large part directed by what Smokey had laying around the shop in scrap. He was trying to get it done quickly. The spring medium is off a truck leaf axle bump stop. I would have done it a different way.

Many people feel there is no safety advantage with a trailing link front suspension and that is why it is not more popular on fixed wings and gyroplanes.

A case can be made that more front suspension travel is a tip over safety hazard with a tricycle landing gear on a gyroplane.

People didn't ask for something different in front suspension from ELA and AutoGyro because they did not want something different, not because they were ignorant.

I have my design compromise preferences and I don't feel the need to be critical of others unless someone asks or someone pretends they know more than the designer.

Your statements condemning ELA and AutoGyro struck me as particularly hypocritical considering what you have most of you gyroplane flying experience in.

 

[Kolibri]

I stand corrected Kolibri Ed was the one who felt there was no trail on the AutoGyro and ELA products.

Thank you for clearing that up.

Sport Copter did not invent free castering nose wheels or trailing link suspension.

I believe that Sport Copter (Jim Vanek) was the first to offer a free-castering trailing-link gyro nosewheel.
That was in 1989.
Where'd you get the idea for the plastic discs with dielectric grease? That's Jim's technology.
I think it's insulting not to give him proper credit for that.

People didn't ask for something different in front suspension from ELA and AutoGyro because they did not want something different, not because they were ignorant.

Those who are ignorant don't even know what they should ask for.
It's called the Dunning-Kruger Effect. We're all subject to it.
I've watched for years at Oshkosh the passers-by at those booths, and they haven't a clue about the net benefits of superior nosewheel designs.
Lots of ooohs and aaaahs over the pretty paint, though.
(I was the same in 2013, and contracted with Chris Lord to train me in a Calidus.)

I have my design compromise preferences and I don't feel the need to be critical of others unless someone asks or someone pretends they know more than the designer.

With some real study and firsthand comparison with better machines, it's not that difficult to know more than some designers.
Remember, the MT03 began as an ELA copy, which was a Magni copy.
In my opinion, AutoGyro lost huge engineering cred with their crack prone <700 hour Rotor System 1.

You statements condemning ELA and AutoGyro struck me as particularly hypocritical considering what you have most of you gyroplane flying experience in.

If I were extolling the RAF as an example of superior engineering, while denigrating AG or ELA, then that would be hypocritical.
However, I think I fairly point out deficiencies in them all. Not trying to skewer any owners in particular.

Fly safely!
Kolibri

 

[Vance]

No Title

I believe that Sport Copter (Jim Vanek) was the first to offer a free-castering trailing-link gyro nosewheel.
That was in 1989.
Where'd you get the idea for the plastic discs with dielectric grease? That's Jim's technology.
I think it's insulting not to give him proper credit for that.

Fly safely!
Kolibr[/COLOR]i

They have had free castering nose wheels on tricycle gear aircraft for as long as they have had tricycle gear.

My father was right in the middle of the development of tricycle gear aircraft.

My 1928 Indian Chief had trailing link front suspension.

My 1930 Velocette had a friction pad for a steering dampener. The big knob on the top set the pressure on a spring just like The Predator.

It is not Jim Vanek's technology.

 

[JAL]

I like using the vertical card compass in The Predator

Vance

Is you VC vacuum driven? I only ask because I have almost the same set up with Garmin 296 next to my magnetic VC and when I turn on my GPS it interferes with my VC, it seems to swing towards the gps by about 10 degree.

Cheers

Jordan

 

[Vance]

Good morning Jordan; that is a good question.

My vertical card compass is magnetic.

When we spin her on the compass rose we have everything turned on.

I have tried turning off the GPS and it did not make a measurable difference.

I don’t see a significant error introduced by either the Garmin 196 or 496 GPS that i use.

On the Cavalon I was flying I installed a clock in the panel and in interfered with the panel mounted vertical card compass significantly and I could not find adjustments that would correct it for the full spin.