Thunderbolt

[Doctordantodd]

Any one seen one of these Thunderbolt gyros from Claudio Pagotta? Looks a lot like my ELA, but has a steel frame throughout.

 

[helipaddy]

Don’t know how the canard winglets on the nose adds to anything

 

[Doctordantodd]

Nice looking plane. Seems to be very little out there information wise.

 

[Doug Riley]

Canards and other aerodynamic surfaces forward of the CG are destabilizing. If nose-up or nose-down bias is needed, it should be created using surfaces out back (the horizontal or vertical fins, as applicable).

 

[Mayfield]

Canards and other aerodynamic surfaces forward of the CG are destabilizing. If nose-up or nose-down bias is needed, it should be created using surfaces out back (the horizontal or vertical fins, as applicable).

Hi Doug,

I suppose you are mostly talking about rotorcraft. Canards on airplanes can work pretty well without some of the efficiency penalties of the more usual empennage, H stab, elevator system.

Jim

 

[Doug Riley]

Mostly yes, but it depends, Jim. I know that you know the following:

To make a canard plane work and NOT be unstable, you need to push the CG forward so that the canard is continually lifting a weight in normal flight . A Rutan is set up with this sort of loading -- sort of a tandem-winger rather than a "pure" canard. In the pure version, the canard would be strictly a stabilizing surface with little to no steady load. The very early canards were like that, and were pitch-unstable -- including the Wright Flyer.

A Rutan canard setup on a gyro would be a disaster, The steady-lifting canard would support some weight but, if/when it stalled, the nose would drop. This, in turn, would reduce the rotor disk AOA and worsen the loss of lift. In a teeter-hinged gyro, loss of rotor thrust equals loss of control power.

The Thunderbolters may be trying to counteract a nose-down tendency brought on by the down-sloping surfaces on their pod. But they'd be better off IMHO either downloading their H-stab or (better) re-shaping the pod so that its top and bottom surfaces have more nearly equal slopes. See, e.g., the nose shape of Glamorous Glennis, Chuck Yeager's supersonic plane. (Sorry, this would require a longer nose gear leg, spoiling the beloved low-slung Euro look.)

 

[Mayfield]

I agree with you that canards are a terrible idea on rotorcraft. On airplanes, they can have some really neat efficiency advantages. One of the advantages that appeal to me the most is the huge reduction in trim drag over conventionally laid out airplanes.

Jim

 

[Doug Riley]

Jim -- yes, for sure on airplanes.

Slight digression:

Another way to reduce trim drag in a conventional FW plane is to eliminate download on the (rear-mounted) HS. You can even put an UPload on it and shove the CG way back. IIR, some pre-WWI planes were laid out this way.

This approach has risky consequences, though. If you stall your lifting tail, the tail will drop and stall the main wing.

My best gyro-flyin' buddy from years ago bought a Cloud Dancer U.L. sailplane that was set up more or less this way. The CG was at about 40% of wing chord, and you definitely had to work the stick all the time. He died in a departure stall-spin entry.

As Chuck Beaty once said, there should be more literature about things that don't work.

 

[j4flyer]

I agree with you that canards are a terrible idea on rotorcraft. On airplanes, they can have some really neat efficiency advantages. One of the advantages that appeal to me the most is the huge reduction in trim drag over conventionally laid out airplanes.

Jim

I have friends that fly canards. They are very efficient when flying however, they need a lot of runway to takeoff and land . The speed in the air on a 4 cylinder is awesome. My buddy has a cozy. He trues out at 187 KTs.

 

[Aerofoam]

Jim -- yes, for sure on airplanes.

Slight digression:

Another way to reduce trim drag in a conventional FW plane is to eliminate download on the (rear-mounted) HS. You can even put an UPload on it and shove the CG way back. IIR, some pre-WWI planes were laid out this way.

This approach has risky consequences, though. If you stall your lifting tail, the tail will drop and stall the main wing.

My best gyro-flyin' buddy from years ago bought a Cloud Dancer U.L. sailplane that was set up more or less this way. The CG was at about 40% of wing chord, and you definitely had to work the stick all the time. He died in a departure stall-spin entry.

As Chuck Beaty once said, there should be more literature about things that don't work.

More CG digression...

I always design with slightly aft Cg for efficiency, but too far and the wing will continue to diverge.
In competition RC sailplanes, the shallow dive test was a standard procedure where you enter a shallow to moderate dive and if the plane pulls up by itself, you reduce, or move back the nose weight until it just maintains the shallow dive. If the weight is too far aft, it will steepen the dive, sometimes rapidly.
With flying wings this it magnified greatly and there is very little margin for error.
Of coarse the airplane design has a lot to do with this, but it applies to the general bell curve of designs, the very old free flight models with lifting tails had a very narrow, but efficient flight envelope and had huge H stabs with lifting foils. You would not experiment with this if you had to actually get in it to fly!!!

 

[WaspAir]

Jim -- yes, for sure on airplanes.

Slight digression:

Another way to reduce trim drag in a conventional FW plane is to eliminate download on the (rear-mounted) HS. You can even put an UPload on it and shove the CG way back. IIR, some pre-WWI planes were laid out this way.

This approach has risky consequences, though. If you stall your lifting tail, the tail will drop and stall the main wing.

My best gyro-flyin' buddy from years ago bought a Cloud Dancer U.L. sailplane that was set up more or less this way. The CG was at about 40% of wing chord, and you definitely had to work the stick all the time. He died in a departure stall-spin entry.

As Chuck Beaty once said, there should be more literature about things that don't work.

In modern sailplane launching practice, flying in the low-tow position, below the towplane wake, makes both aircraft's tails and wings produce lift (upward) and can increase net climb rate for the combination.

 

[Aerofoam]

"In modern sailplane launching practice, flying in the low-tow position, below the towplane wake, makes both aircraft's tails and wings produce lift (upward) and can increase net climb rate for the combination"

Is this increased climb due to down trim needed to counter the tow rope angle of pull and making the thrust path from the tow plane cleaner?
This is new to me and interesting...

 

[Doctordantodd]

Looks like a token addition on this "almost eclipse". I am just wondering about this gyro. I like the eclipse, the heater is nice in South Dakota. If this has removable tanks, steel frame, is lighter, and less expensive then I think it is interesting.

 

[WaspAir]

"In modern sailplane launching practice, flying in the low-tow position, below the towplane wake, makes both aircraft's tails and wings produce lift (upward) and can increase net climb rate for the combination"

Is this increased climb due to down trim needed to counter the tow rope angle of pull and making the thrust path from the tow plane cleaner?
This is new to me and interesting...

The nose of the glider (where the towrope attaches) must be held down to stay below the towplane wake, requiring forward stick and lift on the glider's tail. This pulls downward on the towplane tail through the towrope, also requiring forward stick for the tow pilot and upward lift on his tail as well. Both pilots fly along climbing in formation, both holding forward stick pressure, with all wings and tail surfaces generating lift upward.

The wake of the towplane passes above the glider as the combo climbs, in contrast to the high tow position in which the glider stays above the wake. The wake itself isn't really dangerous, and one passes down through it to change from high tow to low tow (and vice versa), but it is uncomfortable to remain in it. As the towplane climbs, the wake descends relative to the plane's path.

 

[GyroRon]

Unless I am going blind, when I look at the picture of this gyro, the canard looks very small. Looks almost like it is just a gimmicky little fin to just have more fins and bends in the structure for looks. It also looks like there might be LED light strips in the front of the fins, perhaps for landing lights.

 

[Doug Riley]

Could be, Ron. Like fins on an old Caddy. Although -- people have added little canards before, to lessen the nose-down bias caused by pods with sloping windscreens. I believe Ken Wallis did some such thing at one time. I'm not a fan of this tactic.

WASP -- I recall my college soaring club leader saying (in his imperious Nordic accent) "Here, we don't use low tow." He didn't say why. Maybe fear of one plane stalling the other, due to newbie inexperience?

 

[WaspAir]

WASP -- I recall my college soaring club leader saying (in his imperious Nordic accent) "Here, we don't use low tow." He didn't say why. Maybe fear of one plane stalling the other, due to newbie inexperience?

The Aussies are pretty fond of it, but perhaps that's just high tow inverted because they're down under.

There's a disadvantage if you release from low position, with the metal tow ring whipping past the fragile glider canopy. Americans use it for long haul (level) ferry flight, where the wake more directly trails the towplane when it is no longer climbing.

 

[Andino]

Mostly yes, but it depends, Jim. I know that you know the following:

To make a canard plane work and NOT be unstable, you need to push the CG forward so that the canard is continually lifting a weight in normal flight . A Rutan is set up with this sort of loading -- sort of a tandem-winger rather than a "pure" canard. In the pure version, the canard would be strictly a stabilizing surface with little to no steady load. The very early canards were like that, and were pitch-unstable -- including the Wright Flyer.

A Rutan canard setup on a gyro would be a disaster, The steady-lifting canard would support some weight but, if/when it stalled, the nose would drop. This, in turn, would reduce the rotor disk AOA and worsen the loss of lift. In a teeter-hinged gyro, loss of rotor thrust equals loss of control power.

The Thunderbolters may be trying to counteract a nose-down tendency brought on by the down-sloping surfaces on their pod. But they'd be better off IMHO either downloading their H-stab or (better) re-shaping the pod so that its top and bottom surfaces have more nearly equal slopes.

I agree with you that canards are a terrible idea on rotorcraft.

If the canard stalls, dropping the nose of a negative incidence cabin/high thrustline gyro with powerful engine (160-195hp) at throttle, then what?

 

[Doug Riley]

If you chop the throttle instantly, you might live. Or maybe not.

That was the lesson drilled into RAF flight students. And Bensen students, for that matter.