Retractable Mains?

NoWingsAttached

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I've never seen any photos of folding or retractable mains on a gyro. Anyone know of such a craft? Seems easy enough to design, just fold the upper struts in the middle and hinge the lower strut at the keel. With the slick airflow, it seems like an obvious upgrade.

Comments? Photos?
 

WaspAir

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You'll add weight and complexity for little total drag improvement, I'll bet. Think about how much drag that rotor system makes, and how much drag your wheels make, and you might agree with me.
 

choppergabor

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I've never seen any photos of folding or retractable mains on a gyro. Anyone know of such a craft? Seems easy enough to design, just fold the upper struts in the middle and hinge the lower strut at the keel. With the slick airflow, it seems like an obvious upgrade.

Comments? Photos?
You obviously don't follow my thread. I do have a folding main.....:sad:
 

gyromike

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Years ago Craig Wall built a set of folding mains on his Bensen. They hinged forward.
I don't recall what his conclusions were.
 

phantom

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retractable mains

retractable mains

I think the bensen gained about 10 mph with the gear folded, a gyro with a pod would likely gain more if you could keep the weight down. I once took the gear off a challenger and flew it off a sled to get it home and it was over 20 mph faster.
Norm
 

Doug Riley

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A fellow from the southwest built a folding-gear Brock-Bensen years ago. The PRA mag covered it. He cut and hinged the usual 2x2 tube with vertical pins on each side inboard, near the keel. The wheels and axle folded forward, under the seat.

You have to wonder about this setup, though. Turning the disk of the wheel broadside to the air (even disturbed air near the seat) is apt to create more drag than leaving it out in the breeze edgewise.

The biggest reduction in parasite drag on a gyro will come, not from a front pod or folding gear, but from streamlining aft of the crew area. The suction behind the seat, combined with messy flow into the prop, are the real power-eaters.

Streamlining a tubular axle or mast is almost the same, aerodynamically, as taking it out of the airstream altogether. A reduction of 90% of the tube's drag is very possible.

Since the lift-to-drag ratio of a good rotor is only about 5:1, there's only so much performance improvement to be had from streamlining the fuselage -- especially if the streamlining adds much weight that the rotor has to lift.
 

WHY

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These are very good points, look at what Genesis is doing. The conventional line of thinking has always been "more power" but a LOT can be done with drag reduction, one should always remember, double the speed, quadruple the drag. In the "old days" it was balsa fairings wraped with fabric and dope.

Tony
 

WaspAir

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You'll add weight and complexity for little total drag improvement, I'll bet. Think about how much drag that rotor system makes, and how much drag your wheels make, and you might agree with me.
Since the lift-to-drag ratio of a good rotor is only about 5:1, there's only so much performance improvement to be had from streamlining the fuselage -- especially if the streamlining adds much weight that the rotor has to lift.
Doug, I think you just quantified what I had in mind!
 

RayPierce

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Barnwell ROC

Barnwell ROC

Years ago at a Barnwell ROC I remember one gyro that had a retractable nose gear. It was a beautiful machine.
The pilot banged up the gyro when he forgot to extend the nose gear on a landing.

If I find the picture I'll post it.
 

Friendly

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Years ago at a Barnwell ROC I remember one gyro that had a retractable nose gear. It was a beautiful machine.
The pilot banged up the gyro when he forgot to extend the nose gear on a landing.

If I find the picture I'll post it.
I thought a retractable landing gear was one of the things you could not do to a an experimenta aircraft. maybe I dreamed that.:noidea:
 

Minnesota_Mike

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I.M.O....
Wheel pants and air foils on structural tubing would garner the best return on drag reduction vs. added weight and complexity of retractable gear.

(BUT...I really do like the sleek overall look of retractable gear though).

M-M.
 
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Coraview

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Tim Ramseyer did this in the 90s

Tim Ramseyer did this in the 90s

Folding gear on a bensen type gyro was done by Tim Ramseyer of Arizona in the late 80s or very early 90s.

They folded forwarded.

His ship was powered by a Kawasaki KZ1000 engine.

He said his ship was not successful but I do not know if that was because of the engine or retractable gear.


The retract did increase his airspeed.

Coraview
 

NoWingsAttached

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The biggest reduction in parasite drag on a gyro will come, not from a front pod or folding gear, but from streamlining aft of the crew area. The suction behind the seat, combined with messy flow into the prop, are the real power-eaters.

Streamlining a tubular axle or mast is almost the same, aerodynamically, as taking it out of the airstream altogether. A reduction of 90% of the tube's drag is very possible.

.
I agree, and that's why I started behind the seat with drag reduction. Next is perhaps the square tube mast for airfoil clean up. I am thinking the best way to do the retractable is with a hinge in the middle of the upper strut, with a simple spring to extend them and a snapping lockpin to keep them as failsafe as possible. The wheels will tuck in against the mast, behind the cockpit fairing, which is to be clear plexiglass. Guess I'd better read more about the Behemoth. Did we discuss the retractable gear at B'Days? I guess mebbe so.

The cockpit should have a removable targa top for the sporty comforts of summer flying of course.
 
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