Can Gyro’s be brought down safely on auto-rotation?

[John Young]

Hi Gyronauts,

Need some help here please.

Can Gyro’s be brought down safely on auto-rotation with an engine out? I just hear conflicting opinions.

What is –

Safe height? coupled with …

Required airspeed?

for an engine out ….

Do pilots and instructors practice this?

Regards
John ZU-CIB

[Eggbeater]

Hi John

A gyro is always in auto rotation so there is no problem and no minimum safe height.

Power off landings are practised extensively during training and I used to prefer them because I did not have to worry about throttle/power management.

One thing that my instructor did a few times at Kitty was close the throttle just after take off and then I had to put it down without power on the remaining runway.

Let some of the more experienced guys have their say but I am sure that it will not differ materially from the above.

[FO Gyro]

Just to refine the previous post, as per the attached graph, the height velocity graph shows the safe combinations of speed and height in a gyro. A similar, but more restrictive graph exists for helicopters as well.

If flying at 20 mph, at 100 feet AGL and below, and an engine failure occurs, the average gyro will end up landing very hard, with possible damage, and I would imagine spinal injuries would occur. A safer minimum speed at this low height would be around 40 mph. The higher one is, the safer it is to be at a low airspeed. Staying to the right of the solid line is considered safe in a gyro.

It is interesting that in the case of a Robinson R22 helicopter hovering at 500 feet and below, should he experience an engine failure, it is not enough height to lower the collective, in order to enter autorotation. In other words, a R22 should never hover below 500 feet (unles he is a couple of feet above the ground where a safe landing can be made).

[Learjet]

Hi John,

Just to add to Eggbeaters reply, IMHO gyros are THE safest aircraft to land in the event of an engine out. Apart from being in a constant state of autorotation, gyro landings can be done with a minimal and even zero touchdown speed and ground-roll! The safety benefits of this are obvious - especially in a worst case scenario of having to do a landing in rough or bushy terrain where a gyro can literally be brought to a "stop & drop" over rocky ground or bushes.

Other than landing into a strong headwind, virtually all my landings are "power off" at idle - dropping the nose to maintain airspeed (and airflow over the rudder in order to maintain rudder authority) before flaring for a short-stop landing.

Greg Gremminger explains it well in his article on Dead-stop landings:

The main difference in a gyro power on landing from a fixed wing is that the rotor won’t stall at ever increasing angle of attack as the
machine slows down, where the fixed wing is limited in how slow it can go
before it stalls.
There is an extra energy storage medium in a gyro (rotorcraft) - the spinning rotor. Rotors can store and transfer energy! There are three major energy sources in a fixed wing aircraft - fuel (engine power), HEIGHT and SPEED (inertia). In a gyro, there are four energy sources - fuel, HEIGHT, SPEED, and rotor RPM (inertia).
What makes a gyro a lot different than a fixed wing is how it can use and transfer the extra energy storage in the rotor RPM.The advantage in a gyro “deadstick” type landing is this: There is extra energy momentarily stored in the rotor RPM during the high “g” flare. A steep, high speed approach converts HEIGHT energy into SPEED energy, some of which further converts into rotor RPM energy also. The result is more total energy at the beginning of the flare.

A slow or dead stop landing is achieved with a steep, fast approach (well over the power curve) and a very quick flare. Start from high enough altitude to fully convert your HEIGHT to SPEED and rotor RPM. The high speed approach and a quick flare result in higher “g” force that momentarily stores the extra rotor energy for slow touchdown.

Full article here http://www.magnigyro.com/USA/feature_ar ... adstop.pdf

[Low Level]

Hi JY - interested to know what the conflicting opinions are.

FO, thanx for the graph. Answers some of my questions I've pondered over.

Already well explained, but some further useless info. During training, on a height of approx 2000 feet AGL, we've cut the power, and pulled back the stick to go in a hover. With zero airspeed, we "fell" 500 feet, gradually picking up downward speed, reaching a terminal descent speed of 1200 ft/min. This relates to about 22 km/h.

If all systems fail, with rotor intac, you will most propably still survive.

[John Young]

Hi JY - interested to know what the conflicting opinions are.

FO, thanx for the graph. Answers some of my questions I've pondered over.

Thanks guys,

This question comes up quite often.

FO - your graph puts a good perspective on the question - thanks.

OK Ldel – I am going the “no names and no pack drill route” to avoid “negative stuff”, but a true story ….

An experienced 3-axis and microlight A Grade instructor was taken for a flip in a gyro by a gyro instructor. When back overhead the field, the gyro instructor was asked if he could cut the power and land. The gyro instructor did not think that this was a good idea. Conditions were moderate and the circuit was clear.

This left us non-gyro guys wondering – hence the post.

I see microlights and fixed wing pilots practicing glide approaches all the time as I do in my microlight – but I have never witnessed a gyro “cut the power” at 1 000’ agl. Hence my other question, do gyro pilots and instructors practice this routine?

Can we then safely say that all the gyro’s flying locally will perform within the graph as posted by FO if they are flown properly?

Regards
John ZU-CIB

[FO Gyro]

I as a matter of fun, always slow the gyro down to zero mph, overhead the airfield at 1000 feet (or even 2000 feet), and then perform a vertical descent. There is nothing at all dangerous about that.

At around 300 feet, one slowly starts to push the nose of the gyro down, to gain some forward speed again, aiming to get around 50 mph (or 60mph if 2 up) by the time the gyro reaches the ground.

It's the weirdest thing in a gyro calling short final, when the threshold is 1000 feet below you, and your airspeed reads zero, but the gyro is perfectly in control (unlike a fixed wing that has sloppy contols near the stall).

It's a very gentle manoeuvre, and might look windgat to some, but gyro's love it!

[mak]

John

Yes, destructors do practice this with students. I am currently busy with my training and that is exactly what we have been doing for the last three hours, take all power off at 500 & 1000 feet and then managing speed and decent while gliding for a controlled landing.

[Gyronaut]

We practice engine outs until it comes out our ears on both helicopters and gyro's! Once you're comfortable that you will be able to put it down in almost any small area, then flying becomes fun.

Interesting that a helicopter has a minimum height at higher speed which a gyro doesnt have. This is simply because the helicopter will descend while transitioning to autorotation which a gyro doesn't have to do. People glibly say, a gyro cannot stall, so big deal. Its exactly this fact that makes it the safest mode of flying. A fixed wing has to move through the air at just above its stallspeed on landing. Its slowing down that hurts you. Gyro's fuselage speed can be brought to a stop for a zero-roll on landing while the wing is still generating lift.

[Gyronaut]

a R22 should never hover below 500 feet (unles he is a couple of feet above the ground where a safe landing can be made).

At altitude a R22 with two normal sized guys and any more than half tanks battles to hover out of ground effect in any event. On a hot day it descends as fast as my gyro does.

Generally hovering is the one thing that helicopter pilots avoid, in or out of ground effect. Supposedly the only thing a Gyro can't do.

[FO Gyro]

Very interesting graph. That's why these forums are so powerful. Thanks.

[Low Level]

JY wrote

When back overhead the field, the gyro instructor was asked if he could cut the power and land. The gyro instructor did not think that this was a good idea. Conditions were moderate and the circuit was clear.

Hi John

Must say it is strange. I did my intro with a highly experienced, but in my opinion - after I've seen gyro's capabilities - conservative gyro instructor.

My one and only intro approach was from 1000 ft, no power, hover down to approx. 400 ft, nose down, speed up, glide landing. That is the most incredible feeling in a gyro. There and then I was hooked, and decided when I've got my wings, this is the way I will always land.

In a gyro you do not do glide approaches to practice it, you do it because it is FUN.

Later I found out you can do a low approach at 90 mph, at the threshhold, 20 ft height, cut power, and within about 60 meters slow it down to zero and land it - just as much fun.

I also found out ...