Side slipping for short field landing

[ckurz7000]

Picture this: you are flying along nice and easy when suddenly the noise quits. The landing site you've got picked out is a small field with a standard 50 feet row of trees at the approach end. You need to come in real steep to clear the obstacle and still be able to put her down in the field.

So what I am asking for is the best technique for the steepest descent and shortest ground roll offering the widest margin of safety and controllability. I know of two applicable techniques under these circumstances:

1) The one taught most often (at least in Germany) is to do a vertical descent to about 150 feet AGL then dip the nose down smartly to pick up speed for a quick flair and hopefully a good landing without damaging the gyro too much.

2) The one I favor is to establish a reasonable speed (about 40-50 mph in an MT03), then enter an aggressive side slip keeping the nose in about the same attitude relative to the horizon. About 10-15 feet off the ground you exit the slip, flair and land.

Before I put this up for discussion, I'd like to state my case:

I don't like the first method because without engine you don't have an effective rudder, which makes control in a vertical descent impossible. You'll actually start turning slowly but uncontrollably around the vertical axis. If you want to prevent this, you have to keep some airspeed going, in which case your descent path is not that steep at all anymore. Also, you lose a lot of height regaining enough airspeed for a successful flair. If you misjudge here, your landing will be real hard. Furthermore, if there should be any crosswind component, you have virtually no control to prevent getting blown sideways.

When you are slipping, you have full control over your ground track and can offset any cross wind component easily. Your rudder is active all the way down. And as soon as you kick out the slip, you find yourself with enough airspeed to flair with very little loss of height in the process. Overall, you have more control and a wider margin of error while still maintaining a steep approach path with a short ground roll.

What say you?

-- Chris.

[Bcoz]

(Sorry for bad english, hope you will understand ..)

Hi Chris,

I'm used to practice your #2 method, as I feel a better control of path in this way, and I can land exactly where I want this way.

But: I'm not sure that it's the better way to clear a row of trees and land immediatly behind.
When you do an agressive side slip, you do have a forward speed (unless it's not a side slip) even if your IAS is 0, and I'm not sure that your ground path is shorter than with #1 method.
My own method for a short landing after clearing an "hight" obstacle is to do a vertical descent at 0 airspeed to about 250 feet, then establish a minimal speed around 40/50 km/h (if needed, make some S), then doing a last diving after the obstacle at around 50 feet to gain the 20/30 km/h needed for flair.
(height and speed indicate being alone in a MT03).

Bruno

[brs]

I don't like either of your options. Gyros excel at very tight turns which loads your rotors with lots of extra energy which can be used to your advantage. Seems that a spiral just tight enough to keep you clear of the trees could be maintained to the ground then the stored energy would help in your arrest of the descent.
What do you think?

[Redbaron]

I watched ron perform these at wachula ny, he would fly the pattern then when over the runway he would spiral down then gently kiss the runway then take back off and do it again.

I don't like either of your options. Gyros excel at very tight turns which loads your rotors with lots of extra energy which can be used to your advantage. Seems that a spiral just tight enough to keep you clear of the trees could be maintained to the ground then the stored energy would help in your arrest of the descent.
What do you think?

[Vance]

I like a modified number one Chris.

I slow to about 10kts and let her point into the wind. I drop the nose at about 200 feet to reach 60 kts and flair.

I generally don’t do a true vertical descent because it seems to me the controls get a little vague.

If I have not walked the field I would try to do a full stop before touchdown.

I like this because the slow flight lets me know which way the wind blows as she weathervanes into the wind more the slower I fly.

I seem to have a lot of options as far as where to put her down.

I also practice the spiraling descent.

I have found with my aircraft that I cannot descend as fast in a slip or perhaps not slip enough to descend fast.

I would think that every engine out would require a slightly differently technique and that is why I practice often so the options are well known and accessible.

I am a fairly new pilot and expect to change my opinion about many things as I gain experience.

I fly a two place open tandem with a particularly large empennage. She is very stable and reacts slowly. I would be less comfortable being so aggressive in some other two place gyroplanes I have flown.

Thank you, Vance

[birdy]

BRS is rite.
A preloaded rotor gives you the most control over decent rate and approch [ specialy from the hights you blokes are talkn bout] and you pin point it to where you want it, And the exrea energy stored is very useful if you miss judge.
The thing that will catch most people out wen tryn to land ina tight spot, even with power, is the steepness of the gradient soons you drop below the tree line.
You may have the perfect approch, and be able to time the flare zactly, but that aint worth jacks if you dont allow for the gradient.
A preloaded rotor means you can still be at near 90* bank till just off the ground, level off and arrest any ground speed in a very short distance, and spot it.

But, most singles can drop off a line if 50' trees at less than 30mph and still have enuf hight to dip and flare gently. With or without wind.

[ckurz7000]

Interesting discussion all around. It seems that the preloaded rotor technique ought to be option number 3 on the list.

What I had in my mind, though is something like a tight clearing in the woods. I wouldn't feel comfortable with a vertical (or nearly so) descent simply because of the susceptibility to changes in the wind. Your airspeed can go south quickly and unexpectedly and you're in for something harder than you bargained for.

I have experimented with the rotor loading technique and was somewhat hampered by the low inertia rotor on the MT03 (a very light extruded aluminum rotor). As soon as you have cranked up the rrpm in a tight turn, they are gone the second or two afterwards. So it can become tricky timing the touch down just so. If you're only a tad too fast or too high in the turn you lose rrpm before you can touch down. Also, you need some room to menoeuver close to the ground.

In my experience slipping a gyro is something that's not taught or not taught sufficiently. Most pilots I meet have an innate fear or dislike of slips that I can't fathom. When you do them right, I the descent can be very steep and still be well on the safe side. I'll have to quantify that on some of my next flights.

Thanks, -- Chris.

[GyroDoug]

I know this is going to come accross to some as me being a smart eleck, but I say this because I think people should understand the capabilities of the Butterfly Line of Gyros and what it could mean to you and your safety especially in less than ideal circumstances.

If you fly a Butterfly Gyro with the G-Force Landing Gear (or any other custom design that has the same capability) there is a third option. Larry Neal has demonstrated the capabilities of the G-Force landing gear dozens of times. He can fly a nearly vertical descent (with a 15 mph forward speed) and fly it all the way to the ground, with no flair at all and do a zero roll landing with absolutely no damage to the Gyro. Many have called this landing gear a fancy gimnick that really isn't needed. I beg to differ. I believe the capability of the G-Force landing gear brings a VERY BIG safety margin to flying that can take many unusual situations that could turn into a serious problem in a Gyro with typical landing gear, and turn it into a Non-event in a Butterfly. I think people should realize what an advantage that could be under the right circumstances. I just wanted to bring it up here because the situation you describe is a perfect example of what would be no big deal in a Butterfly.

[birdy]

a very light extruded aluminum rotor).
??
Didnt know there was such a thing.

As soon as you have cranked up the rrpm in a tight turn,
Crank um up sum more then.
Iv dun an inertia stop on, i think, on 23' Benson blades, [ sorry Mitch, didnt tell you that one did i], and they would be alot lighter n any extruded blades. Its not so much the amount of stored inertia, but how you use wot youv got, and from more n 100', you can have plenty.


Also, you need some room to menoeuver close to the ground.
You dont need any room in an inertia hover, coz you aint moven.


When you do them right, I the descent can be very steep and still be well on the safe side.
Chris, im not tryn to be a smartass, but the rotor dont know wether your side slipn or ina steep low AS decent.
So the rate of decent and forward AS aint go'n to be alot different from a slow steep decent to a slipn decent, so the rotor will do zactly the same thing on either approch wen you start the flair, and will be startn from the same rpm.
[ but, the machine will already be pointn the way its traveln wen you get to the ground ina streight drop. If you leave the rudder too late, god knose which direction its go'n to be pointn wen you have buggerall AS and no noise.]

y have called this landing gear a fancy gimnick that really isn't needed.
Thatd be me ;)

[Resasi]

Having come from fixed wind the side slip method had always been a natural maneuver to use in such a situation.

The tight spiral in a gyro, though alarming to me to in the beginning, is so very tight and controllable in comparison to that of a fixed wing, that I am glad to see it being endorsed here by Birdy and others as possibly the optimum solution.

[troed@aon.at]

How would You estimate the failure/crash-danger of an emergency side slip landing for the average gyro-pilot compared to the standard procedures ?

[WaspAir]

In some gyroplanes with enclosures, yawing will produce an adverse roll, and attempting to hold a prolonged slip in one of those may not be the wisest of plans.

Personally, I've never found getting down steeply to be too much of a problem, as most gyros have the glide ratio of an anvil.

[MichaelBurton]

I choose option #3 the tight spiral descent. I like the way it loads the rotor and keeps the landing site in view. It is easy to control and decide when to roll out. If you get dizzy easily you could make steep "S" turns for the same purpose. I have tried this and love the extra cushion you get when you roll out close to the ground. It allows for a lower ground speed without a high descent rate at touchdown.

The side slip does little to enhance the rate of descent on many gyros(with the engine out). I would not use this for my gyro as I have tried it at altitude and it is possible to have it "swap ends" if the doors are on. I have not tried a side slip with the engine out but don't like the idea of little rudder control and the fact that the gyro would not be facing the the direction I want for the landing roll.

The vertical descent while doing a good job of increasing the rate of descent requires some forward speed for rudder control and for the best result it requires a perfect recovery from the slow airspeed. I have used this technique a few times and it works quite well. This would be my second choice for my gyro.

You could also combine the slow airspeed and spiral descent to increase the descent rate. I don't know why I need to get to the ground fast but this would do it.

[Redbaron]

Not to mention fun "as long as its practice" those g forces give me a warm fuzzy feeling inside! :wacko:

I choose option #3 the tight spiral descent. I like the way it loads the rotor and keeps the landing site in view. It is easy to control and decide when to roll out. If you get dizzy easily you could make steep "S" turns for the same purpose. I have tried this and love the extra cushion you get when you roll out close to the ground. It allows for a lower ground speed without a high descent rate at touchdown.

The side slip does little to enhance the rate of descent on many gyros(with the engine out). I would not use this for my gyro as I have tried it at altitude and it is possible to have it "swap ends" if the doors are on. I have not tried a side slip with the engine out but don't like the idea of little rudder control and the fact that the gyro would not be facing the the direction I want for the landing roll.

The vertical descent while doing a good job of increasing the rate of descent requires some forward speed for rudder control and for the best result it requires a perfect recovery from the slow airspeed. I have used this technique a few times and it works quite well. This would be my second choice for my gyro.

You could also combine the slow airspeed and spiral descent to increase the descent rate. I don't know why I need to get to the ground fast but this would do it.

[getut]

I practice the spiral descents every time I go out to fly but I still find my control of any 2 of the 3 critical factors to be good, but when I try to do all 3 I rarely get it perfect.

I start a spiral at idle with the intention of the following:

1) come out of it very close to my intended altitude
2) come out of it headed in the intended direction
3) come out of it very close to my chosen airspeed... usually 40-50 mph for good high energy flare.

You guys know what I mean. I can come out of it in the right direction and at the right altitude, but I might have to severely tighten the last turn which bleeds off too much airspeed. Or I come out of it at the right airspeed and right direction but either had to forfeit one turn and come out early because I didn't have enough alt for another revolution.

End result is they look cool from the ground but would be useless if my landing area was of the "absolutely had to get it perfect" size.

I can ALWAYS do any 2 of the things perfect. All 3 is very difficult for me and I've done a good hundred of them now solo, not counting the ones I did in training.

I usually use an imaginary plane at treetop level around a practice landing area as my landing field. I use an actual landing area the size I want to practice with surrounded by trees except I move the landing plane up vertically. I pretend like I am flaring to land at treetop level then power out and do it again. I do it that way rather than focusing on altimeter to do it.

[birdy]

I pretend like I am flaring to land at treetop level then power out and do it again.Not a very safe way to practice.
If the noise stopped wen you attempt to power out, your deep init, coz you got low AS, low RRPM, and still too far off the ground.
And most carb ice happens just there where your go'n to need it least.

Why not take it to the ground?
Least youll be nearly onit if the noise stoped.

[getut]

I should have elaborated on that. I knew when I typed it someone would misunderstand that. If I see that I am going to be slow I go ahead and power out. I don't actually bring it all the way down to an unsafe speed at that height.

Once I get to where I can hit all 3 almost every time, I'll move my landing "plane" down closer to the ground and start either touching down all the way or coming close to it.

If I have a big field or a runway I am practicing over, not a tight one I actually go ahead and do that already. If I need to drop one spiral so end up higher than I need and it pushes my landing further down the runway or field.. no biggy I have room.

[MichaelBurton]

I think it is harder to hit the perfect altitude in part because you are looking at the instruments inside the gyro. When you do it for real you only need to look out the window. All of your attention will be focused. Practice at idle power if the landing looks like it will be less than perfect abort and go around.

As a note I have found that the glide ratio is better with the engine off than it is at idle power.

[reelmule]

I agree Michael, about the glide ratio being better with the engine off since the prop is stopped and not windmilling. On most aircraft zero thrust is about 1100-1200 rpm; I've found that setting my erpm at ~ 2350-2400 rpm simulates zero thrust which is what you have when the noise stops. Off course if you practice at true idle your glide ration will be steeper than the real emergency, which should be a good confidence builder for the new and intermediate gyro pilot.

[ckurz7000]

I agree Michael, about the glide ratio being better with the engine off since the prop is stopped and not windmilling...

Don't know about that. In the MT03, MTOSport, Calidus, ELA and I bet also the Magnis M16, M19 and M22 the power off glide ratio is markedly worse than with the engine idling. The MT03 handbook lists 4:1 at idle and 3:1 with power off. That kind of tallies with my experience.

-- Chris.

[ckurz7000]

In some gyroplanes with enclosures, yawing will produce an adverse roll, and attempting to hold a prolonged slip in one of those may not be the wisest of plans...

Apparently the enclosed gyros you've been flying handle quite differently from the MT-line of gyros or the Calidus (and I bet also from the ELA and Magni gyros since they are very similar to the MT). All those slip nice, steep and stable. When you keep up about 60-70 km/h (on entry, while slipping you just keep the same nose down attitude as the ASI will be reading too low), the rudder is effective and you've got plenty control. 10 feet off the ground you kick it straight, flair and land.

In my estimation the descent path is at least as steep as with a vertical descent in which you have enough forward speed to gain effective rudder use.

What can I say, I like it as an option. Maybe it's just personal preference. But it's a tool in my box that I'm glad to know how to use.

-- Chris.

[wnwgj]

Don't know about that. In the MT03, MTOSport, Calidus, ELA and I bet also the Magnis M16, M19 and M22 the power off glide ratio is markedly worse than with the engine idling. The MT03 handbook lists 4:1 at idle and 3:1 with power off. That kind of tallies with my experience.

The only guy here I know who has tried this on an MT-03 told me that once the engine has stopped, the only field you are going to land in is the one right underneath you!

[WaspAir]

Apparently the enclosed gyros you've been flying handle quite differently from the MT-line of gyros or the Calidus (and I bet also from the ELA and Magni gyros since they are very similar to the MT)...

What can I say, I like it as an option. Maybe it's just personal preference. But it's a tool in my box that I'm glad to know how to use.


That's why I said "some". If there's lots of side-surface low on the aircraft body with respect to the vertical position of the center of mass (you could think of it as a center of pressure issue), you can get some surprising rolling behavior if you yaw out of coordinated flight. One should, of course, certainly know the behavior for the particular aircraft in use so that one is not surprised by it.

The photos of the prototype McCulloch J-2 always show wheel pants and a nice tapering cowl behind the mast. On the production models, the pants were gone and a large triangular fin appeared high behind the mast. I have always suspected that this was to balance the high/low surface area to prevent the effect I'm describing. It can be noticeable in some sport gyros with a open-top, low pod, depending upon the design, and is really notable in the A&S 18A (at one time they carried slip warning sensors and alarms).

Of course, as is usually the case, the whole issue becomes academic if you pick your routes carefully, avoiding the need ever to land in the only clearing in an entire forest.

[birdy]

I've found that setting my erpm at ~ 2350-2400 rpm simulates zero thrust which is what you have when the noise stops.
Cept wen you get to the ground and flare, coz at that rpm, youv got rudder. At 0 rpm and 0 AS, youv got nuthn.

[Friendly]

Birdy,
it would be nice if you posted a video of what you were describing and narrate it or put some captions in the video so we could fly with you.

[birdy]

Sumwhere in this old vid http://www.youtube.com/watch?v=yoeDCJE_5hA , where im scootn down the strip then pull up, cut power, do a virtical 180 and level off, THEN power on is no different, only less room for error.
If i didnt power on, id just flare to a spot stop.

[Resasi]

Birdy and his mechanical Quarter Horse. You played with that buzzard a bit.

I like the s turning power off descent just to the side of the runway. It demonstrates very well the vertical drop with maneuverability and ability to choose a very tight landing spot. Vid 2 giving a very good observers viewpoint of that.

Just got to love that ending though. Don't know how many times I've watched those two vids, still great to see.:first:

[birdy]

Mate, that was a few years ago, wen it was only a young colt, you want to see it move now that iv got it trained. ;) [ and feedn it steroids.:)]

[Resasi]

It has to be a very much more powerful and capable machine, and I have do doubt you have a lot more time, and moves under your Ikubra.

That was a very interesting set up, in that we had a view from the machine on one video, and a spectators view on the second video.

If you could get another two made in the same way Birdy, they would make for some top class footage.

Exciting, interesting as well as instructive. Particularly if you planned out a sequence that demonstrated a series of techniques and useful maneuvers.

Any chance, between the business of managing your spread and mustering moos.

[birdy]

Particularly if you planned out a sequence that demonstrated a series of techniques and useful maneuvers.
Nuthns ever planed ere Leigh. ;)

Any chance, between the business of managing your spread and mustering moos.
??????????

[Resasi]

Sorry Birdy, I meant, any chance of shooting two videos (one from the aircraft and one from the ground) of a planned sequence of useful manouvers.

In between the business of managing your spread and mustering moos...or being grounded by rain?

[birdy]

Only two chances..................;)

As i understand it, a planed sequence would mean organised and in control.
No chance. :)

[Resasi]

Yup you are a bit of a free spirit.

Oh well, just an idea. :( Guess we were lucky to get those two.