Could Gyro-Gliders Soar?

[PW_Plack]

I've been thinking a lot lately about gyro-gliders and their potential to be an economical entry into the sport. Most towed trainers are not really gliders, but must be continuously powered by a tow vehicle, and lack functional rudders which would be needed for safe free flight and landing.

I'm thinking about gliders which could be released, flown for a while, and landed.

There are established ratings and standards for the operation of gliders, but the ratings and endorsements require instruction in soaring techniques. I know the rule of thumb for a Bensen-like gyro is a glide ratio of about 4:1, which can be bettered somewhat with improved aerodynamics. I've also seen the video of the foot-launched gyro-glider on YouTube.

Questions:

Could a gyro-glider be cleaned up enough aerodynamically to soar in anything short of a cumulonimbus updraft?

I've had personal friends who got into lift unintentionally, and reported 2,000 FPM or more in uncommanded climbs. In every case, it happened under cumulus clouds, which if not escaped could be serious trouble. But what about terrain features which produce ridge lift? Could an unpowered gyro have the capability to stay out of trouble, or would it take constant, expert attention to keep it off the rocks?

If a gyro-glider could be launched near a reliable source of lift, could it be capable of sustained soaring flight for long periods?

If the launch zone was too far from the source of lift, would it be practical to launch a gyro-glider with a fixed-wing tow plane and get it close enough to catch the lift?

If this could be made to work, it might be possible to enjoy flying on a greatly reduced budget, and the minimums for instruction for a glider add-on to a powered certificate are as little as three hours.

 

[EI-GYRO]

Ken Brock got aero-towed to a couple of thousand feet in a gyroglider and released.
I can't recall the figures, but IIRC he was impressed with the rapidity with which he
lost height.
My own very limited tow release experience would suggest the glide rate may be poorer than a glide in a powered machine.
You have to stuff the nose right down to maintain a glide speed, even just to slacken
the towrope.
The glider guys talk about polar curves, of which I have only a hazy understanding,
but I think the light weight and high drag work against a gyroglider.

In short, I would be very surprised if you got anything useful out of it for soaring.

I THINK Ken Brock mentioned a descent rate of 1100 or 1200 fpm.
Maybe someone else remembers better.

Just my .02

 

[SandL]

glide ratio of a kirby cadet mk3 (T31) was 18.5 to 1 and
glide ratio of a dagling (T38) grasshopper was 8 to 1

I have thermal soard a T31 but never a T38 to keep the T31 up in thermals you needed a rocket of a day, I suggest you would be outclimbed by a hanger on a day you could soar a T38 so a gyro glider would be impossible to thermal soar.
The only chance you would have is using ridge lift or to bungee off a cliff top soaring along a ridge would need a huge updraft created by a very strong wind, penetration into that wind to get to level ground for landing would be a significant issue and keeping the thing from rolling back or rolling over on landing would take very significant skill not something for a student to handle. I dont even think you would find any experienced person to give it a go.
but calm wind, and an experienced guy could possibly bungee off the top of a tall cliff and experience a gently slightly prolonged glide down.
you are almost talking para wing suit glide ratios 2.5 to 3 to one

 

[WaspAir]

The glide ratio is actually the least of your concerns.
The minimum sink rate (vertical speed) is what determines whether you can climb/soar.

If you can achieve a low vertical speed, then you have a chance of finding rising air that is going up faster than you will be going down through it, and you can get a net gain in altitude. You don't need much forward speed as you do this; lift sources are often quite small anyway, and you will need to maneuver at low speed to stay where the lift is good.

If you then want to go somewhere with that altitude, the glide ratio will tell you how efficiently you can use it up.

In my sailplane, I can get my sink rate down to perhaps 130 fpm by flying a little above stall. My glide ratio sucks at that speed, but if I find air going up at say, 250 fpm, I'll get a net climb of 120 fpm to ride upward. That's a pretty weak thermal by western U.S. standards, but I can hang on with patience and get some height. When I want to leave the thermal, I speed up quite a bit to get a good glide ratio, and can use up that altitude at more than 40:1.

The issue for a gyro-glider to soar then is: how slowly can you make it sink, and is there likely to be air rising faster than that in your vicinity?

 

[Resasi]

Could Gyro-Gliders Soar?

In short. No.

 

[birdy]

But what about terrain features which produce ridge lift? Could an unpowered gyro have the capability to stay out of trouble,
Yes.


Ridge Soaring in a Gyro - YouTube

 

[M._Springer]

Leigh is right! gyrogliders come out of the air like a fat rock

Leigh is right! gyrogliders come out of the air like a fat rock

They wanted t see which would descend faster, a gyroglider or a Bensen gyro with Mac engine and the engine shut down.

Ken Brock in his gyro and someone in a gyro glider climbed to the same altitude. I think it was around 200 feet. At the same time Brock shut his engine down and the gyroglider pilot disconnedted from the tow rope. The gyroglider touched down much faster than the Bensen.

The same thing was done later with an Air and Space 18A and a Bensen. In this case the Bensen being lighter, touched down before the 18A .

A man from Stocton, Ca. wanted to " soar in the thermals" with a gyroglider. after a few disconnects from the tow rope and coming down at a heart stopping rate he decided the glider needed more weight to make a slower descent so he put a 50 lb. block of cement on the gyroglider...he came down fast like a glider with 50 lbs. of cement attached. Finally he gave up the idea of soaring a gyroglider and put an engine on the gyro and flew it for many years.
Marion

 

[ckurz7000]

The thing with weight is that it will not change the glide ratio but will increase the minimum rate of descent. So adding weight to a gyro will degrade its soaring capabilities.

To make a gyro soar you would need one with a low disk loading. Something light with a large diameter rotor.

Personally, I don't think gyrogliders can soar in anything but the strongest updrafts. But I have seen gyros soar for hours above sand dunes in strong coastal winds of Spain.

-- Chris.

 

[PW_Plack]

Personally, I don't think gyrogliders can soar in anything but the strongest updrafts. But I have seen gyros soar for hours above sand dunes in strong coastal winds of Spain.

Chris, we have some places here with major ridge lift available. It would just be a question of whether there are launch points close enough to reach them.

Countering a 1200 FPM sink rate would require an updraft moving at about 22 mph (35 kph) to hover, faster to ascend.

Birdy thanks for the video link. Could you have stayed up there or climbed with the engine shut down?

 

[birdy]

Could you have stayed up there or climbed with the engine shut down?
Paul, the 'ridge' was a round hill of 80' max, and the breeze was only bout 15-20kts, but there were a few occasions where i was at idle or just above. Recon if i ejected the dinosour burner it woulda held alt no wurrys if you could trust the wind, but a consistant breeze isnt sumthn we get alot of ere.

Theres a ridge bout 60 miles south of ere thats perfect for ridgen ina gyro.
It runs SW-NE for bout 10 miles, [ not far from where me throttle cable broke] and our prevailing is usualy SE, strate up the 250' cliff.
Iv spent over 20 mins onit at idle ina 20kt breeze. [ coulda stayed there forever but the sun went to sleep]
And the good thing bout a gyro glider is, the godzilla country at the foot of the ridge isnt a problem if the wind suddenly craps it.

 

[Resasi]

I guess I should have been more specific. Orographic lift is a well known phenomena associated with rising ground and prevailing wind.

These conditions are popular for gliding and in certain instances where even large piston aircraft have been known to be able to shut down engines and ridge soar.

There are various weather conditions where even gyrogliders with bricks will not only soar but be carried up to extreme altitudes, but under normal conditions most gyros and gyro gliders are not the most efficient machines at soaring.

As we get better with carbon fibre and other materials that will allow airframes to get very much lighter the situation may well change but with what we have at the moment we are stuck with a pretty steep glide angle unless in unusual conditions.

 

[ckurz7000]

As we get better with carbon fibre and other materials that will allow airframes to get very much lighter the situation may well change but with what we have at the moment we are stuck with a pretty steep glide angle unless in unusual conditions.

Agreed, Leigh. But I still don't think there will be any gyrogliders sold commercially. Just the wrong principle for the task.

Just a quick aerodynamic comment: changing the weight does not cause a steeper glide angle. The glide angle is independent of weight and depends solely on geometric properties of the aircraft.

A glider at a particular airspeed follows a particular slope downwards. The slope determines how far it'll get. The weight says how quickly you get to that spot.

-- Chris.

 

[okikuma]

Rotor Disk Load is not a direct equivalent to Wing Load. If it were so, then a 600 lb gyroplane with a 1.8 lb/sq ft disk load would be able to soar and even climb better than a 600 lb Schweizer 1-26 with a 3.75 lb/sq ft wing load.

A direct equivalent to a wing load is rotor blade load and we know this because a rotorblade is a wing. Get a big enough set of rotor blades that will have 3.75 lb/sq ft blade load and the gyroplane will be able to soar.

Before the discovery of soaring in a thermal (and subsequent designing of light weight gliders with long aspect ration wings), the early pioneers of gliding only ridge soared.

I've personally ridge soared "dead stick" J-3 Cubs, & 7AC Champs.

Some time ago, I read a story of a US Army Aviator being trained to fly a AH-64 Apache. During his training they were practicing flying by night vision goggles during the day time. With the IR goggles, they could see passing "dark columns"/"ghosts" moving across the ramp and country side. Being a sailplane pilot, this aviator reasoned those dark columns had to be thermals, so with permission of his IP, he flew into one and started to circle within the dark column and noticed his rate of climb increased dramatically.

Wayne

 

[WaspAir]

I have found soaring techniques very helpful in gyroplanes when density altitude limits performance, using atmospheric lift as a supplement to engine power (not a replacement for it), especially in mountainous parts of the U.S. Southwest. For example, I have thermalled a J-2 when near the service ceiling but still needing more altitude for terrain obstacle clearance, and I have zoomed up over high ridges by flying at them to catch the deflected wind. It's all free and available if you know where to expect it and how to use it, so there's no reason not to exploit it. I surprised John Potter at Farrington's place once long ago by pulling the power back and thermalling up several hundred feet in an 18A ("I didn't know this s.o.b. could do that", he said).

With no power at all, it's another matter, because you need really strong conditions. I've seen 2000+ feet per minute in mountain wave off Pike's Peak, but I wouldn't relish the idea of towing through the rotor in a gyro to get to it (the outside air temp was seriously negative, too). Thermal lift can be strong in some places in some seasons, but a 1200 fpm thermal that routinely happens near Reno will be incredibly rare near Atlanta. With ridge lift, you're tied to the ground feature that creates it and can't go anywhere. There are a few ridge systems along the Appalachians that can be linked together for long high speed glider dashes, but bridging the gaps in a gyro glider would be one heck of a challenge.

I think its good for airmanship for all pilots to learn a bit about soaring and how the atmosphere works, but a rotary wing glider wouldn't offer much practicality.

 

[Fly Army]

Paul,
I don't think the folks over at Point of the Mountain would be too excited to see something show up with whirling blades ! I've almost had a couple of mid-airs there already in just a paraglider.
Randy

 

[SandL]

Birdys ridge soaring clip

Birdys ridge soaring clip

But what about terrain features which produce ridge lift? Could an unpowered gyro have the capability to stay out of trouble,
Yes.


Ridge Soaring in a Gyro - YouTube

Looked at your youtube clip, can you estimate the wind speed hitting the ridge on the day ? I guess you had about 3/4 throttle to mantain position.

 

[PW_Plack]

I don't think the folks over at Point of the Mountain would be too excited to see something show up with whirling blades!

Randy, that was one place I thought about, but there's also an area east of Spanish Fork where the conditions could be right. I suspect there are also places in the Tooele Valley where west winds against the east side of the Oquirrh Mountains could set up the right conditions.

The trick, of course, would be finding ways to get airborne close enough to catch the lift.

 

[Arnie Madsen]

Not soaring per say .... but I recall old Bensen literature talking about tethering a gyro to a pole on a windy day and soaring around at the end of a long rope .... was there not also some grainy film taken of such a thing in the 1970's ??

 

[okikuma]

J.R.,

I agree with you, I think all pilots of rotorcraft and fixed wing aircraft would gain valuable experience learning to fly a glider through the usage of energy management along with a greater level of weather knowledge is a benefit well earned. I've said this so many times, Capt. Sully is famous today because he learned valuable skills early on flying gliders at the USAF Academy that served and saved his passengers.

Wayne

 

[clytle374]

Often wondered if gyro glider would work. Always thought you'd need 3 or 4 blades that resembled glider wings more than rotor blades, and at least collective trim.
Cory