A part 103 tractor Autogyro?

[BrianInVa]

Hi folks,
I’m really impressed by the Little Wing (LW) Autogyro and will likely start building one this winter.

I just picked up a Brock KB2 today and the original Mac is long gone seller included a recently rebuilt Rotax 503. I have an offer to trade it for a complete Rotax 582 also.

I exchanged emails with Ron at LW and he said the Brock KB2 controls and the 582 would be perfect for a LW build.

Frankly I really like the images I found of a “naked” LW.


We were almost ready to order plans for a Legal Eagle fixed wing ultralight as we like the minimalist look of them.

Question - could a part 103 compliant tractor autogyro be created using an airframe from a Legal Eagle (250 pounds) or LW (350 pounds with full fabric covering)?

Legal Eagle:

Alternately, could the 5” tail boom and empannage from a Kolb Ultralight be “grafted” onto a chrome moly airframe consisting only of the cabin and forward section to save some weight? Would the gyro mast be too much stress on a Legal Eagle airframe?

Please be patient with me if these seem like stupid/ ignorant n00b questions. I am indeed a stupid/ ignorant n00b.

 

[Aerofoam]

There are too many variables to the answer, but probably yes on any sort of conversion if you have the skill set to do it.
I thought the little wing was basically a converted kitfox, but I could be wrong.
A tractor is on my bucket list, but I will design from scratch and it will probably be mostly CF structure and fully open frame....
The legal eagle looks like it would need a lot of extra structure to support the mast and load, probably easier to start from scratch....

 

[GyroChuck]

Ultralight has to be 254lbs or less. Can not contain more than 5 gallons of fuel and not exceed more than 63mph in straight and level flight.

FAA Part 103 Ultralight

 

[BrianInVa]

Ultralight has to be 254lbs or less. Can not contain more than 5 gallons of fuel and not exceed more than 63mph in straight and level flight.

FAA Part 103 Ultralight

Yes. The Legal Eagle ultralight fully qualifies. That is why I was hoping it could be converted into a part 103 qualified tractor gyro.

 

[GyroChuck]

Yes. The Legal Eagle ultralight fully qualifies. That is why I was hoping it could be converted into a part 103 qualified tractor gyro.

You are going to need a larger engine, more weight. How much does it weigh without the engine

 

[BrianInVa]

You are going to need a larger engine, more weight. How much does it weigh without the engine

The Legal Eagle weighs 244 lbs including the 30hp 1/2 VW engine, which weighs 88 lbs.

So 156 lbs without motor. Then subtract wing weight and elevator controls, then add a bigger motor and gyro mast and controls. I don’t know what the wings weigh.

A 64hp 582 weighs 110 lbs with electric starter, carburetors, fuel pump, air filters and reduction gear. The one I’m getting doesn’t have electric start.

 

[GyroChuck]

The 110 lb weight sounds a little heavy. Pretty sure its under 100lbs

 

[BrianInVa]

The 110 lb weight sounds a little heavy. Pretty sure its under 100lbs

Much better then as it’s less than a dozen pounds heavier than the 1/2 VW but more than twice the hp. The 110 lbs was from the 582 Wiki entry.

The 503 is 50hp at 69 lbs. Nothing to sneeze at - best power to weight ratio of all the two stroke Rotax engines.

 

[wolfy]

There are too many variables to the answer, but probably yes on any sort of conversion if you have the skill set to do it.
I thought the little wing was basically a converted kitfox, but I could be wrong.
A tractor is on my bucket list, but I will design from scratch and it will probably be mostly CF structure and fully open frame....
The legal eagle looks like it would need a lot of extra structure to support the mast and load, probably easier to start from scratch....

Pretty sure the airframe started as a modified Preceptor N3 or another 3/4 cub alternative.

 

[ultracruiser41]

Gonna be really hard to hit the 254 lb limit. It’s not as easy as you think…..but….. why not try it

Just remember….a taildragger gyroplane is like a taildragger fixed wing…..ya need to know how to do the rudder dance.

 

[BrianInVa]

I’ve been looking at various home built airframes and comparing them to the Little Wing Autogyro and its mast placement.

One airframe is intriguing because the original Bensen or Brock frame could be directly integrated into its frame, and that’s the Affordaplane, right where the windshield would be. The original seat and controls would then be reused but moved behind mast instead of in front of it:


When compared to the Little Wing airframe and mast position it’s easy to see where the original frame and engine could be incorporated into the Affordaplane frame:

 

[BrianInVa]

If space becomes an issue the foot pegs could be positioned outside the frame, like an AirBike ultralight.

 

[Jean Claude]

A tractor is on my bucket list, but I will design from scratch and it will probably be mostly CF structure and fully open frame....

The advantage of a tractor layout is that the rear of the structure can be very streamlined to reduce drag.
But when it's left open, drag is increased compared with a pusher, from the accelerated flow by the propeller.

 

[BrianInVa]

The advantage of a tractor layout is that the rear of the structure can be very streamlined to reduce drag.
But when it's left open, drag is increased compared with a pusher, from the accelerated flow by the propeller.

That may be one advantage of the Affordaplane frame, images above.

 

[Doug Riley]

Brian, there's a tradeoff between simplicity of construction and low weight. Simple isn't always light.

The Affordaplane frame uses Bensen-style construction. This type employs comparatively heavy extrusions, bolts and gusset plates. The bolt holes weaken the tubes considerably -- so, of course, the tubes have to be that much beefier to be sufficiently strong at the holes. The beefiness adds weight, most of which is wasted, because it's really only needed where the holes are drilled.

If, for example, you built a Bensen-style open pusher gyro, but used Little-Wing style welded-tube trusses in place of the extrusions, bolts and plates, you could expect to save 15-20 lb. or more. If OTOH you built a Little-Wing style tractor gyro using Bensen-type construction, you'd suffer 20 lb. or more extra weight.

So, if you want a tractor gyro, that's cool, but I'd strongly suggest using a welded-4130 truss frame, not drill-n-bolt construction. Lighter still is monocoque construction (Cessna 152, et al). This style employs formed sheet metal and requires some skill, knowhow and tooling. It's hard to beat for lightness, though -- one reason that commercial airliners are built this way. Both of these construction styles are very labor-intensive compared to the Bensen method.

 

[BrianInVa]

So, if you want a tractor gyro, that's cool, but I'd strongly suggest using a welded-4130 truss frame, not drill-n-bolt construction. Lighter still is monocoque construction (Cessna 152, et al). This style employs formed sheet metal and requires some skill, knowhow and tooling

I can work with the chrome moly oxy acetylene welding, but monocoque is and will always be way beyond my meager abilities.

Could a chrome moly frame similar to the A-plane frame be built?

 

[Doug Riley]

The Bensen frame and the Affordaplane frame are 2-dimensional -- like a bicycle. You sit ASTRIDE these frames, not INSIDE them. Their rigidity in the side-to-side direction depends wholly on the bending strength of the tubes, not on triangulation. So that means you're back to big, thick-walled tubes.

Any time you use a tube loaded in bending, it's a beam. Tubes are much more weight-efficient when used in a truss (compression and tension loads only) than when used as beams.

The Little Wing frame is an absolutely classic example of 3-dimensional, welded-steel-truss (a.k.a. space frame) construction. I wouldn't try to reinvent it... too damn much work!

Designing one of these things right means selecting the wall and diameter of each little tube carefully, based on the loads at the various joints in various flight situations (pulling G's, landing, full-throttle climb, etc.). This design process involves some 3-dimensional geometry and math.

Some people love that kind of nerdy immersion. I'd druther go flyin.'

 

[BrianInVa]

The Bensen frame and the Affordaplane frame are 2-dimensional -- like a bicycle. You sit ASTRIDE these frames, not INSIDE them. Their rigidity in the side-to-side direction depends wholly on the bending strength of the tubes, not on triangulation. So that means you're back to big, thick-walled tubes.

Any time you use a tube loaded in bending, it's a beam. Tubes are much more weight-efficient when used in a truss (compression and tension loads only) than when used as beams.

The Little Wing frame is an absolutely classic example of 3-dimensional, welded-steel-truss (a.k.a. space frame) construction. I wouldn't try to reinvent it... too damn much work!

Designing one of these things right means selecting the wall and diameter of each little tube carefully, based on the loads at the various joints in various flight situations (pulling G's, landing, full-throttle climb, etc.). This design process involves some 3-dimensional geometry and math.

Some people love that kind of nerdy immersion. I'd druther go flyin.'

Makes sense. In exchanging correspondence with Ron at LW Autogyro, he seemed to think the current cross piece for the Brock landing gear could be used to brace/ triangulate the mast if it was incorporated into an A-plane frame. He said it’s an intriguing concept, one he would definitely pursue further if he wasn’t retired.

In which case I have to wonder if such a contraption could also utilize the existing Brock tricycle landing gear instead of a tail dragger.

Ok another stupid question, please humor the classroom dolt - there are local Marketplace listings for 3/4” and 1” thick Aluminum Sheet Honeycomb Core Composite Structural Panel. I know some forms of this stuff are used for commercial airplane construction. Any way these could be incorporated into an A-plane or other airframe, maybe in place of cross braces?

I’m thinking of something similar to engineered beam, but use the honeycomb aluminum between 1”x2” aluminum tubes in the shape of the tail boom.

 

[LGoodhind]

The Bensen frame and the Affordaplane frame are 2-dimensional -- like a bicycle. You sit ASTRIDE these frames, not INSIDE them.

That reminded me of this photo that was posted around 20 years back- no idea about the origin. Thick Styrofoam with a glass lay-up. No idea if this ever left the ground.

 

[Aerofoam]

The advantage of a tractor layout is that the rear of the structure can be very streamlined to reduce drag.
But when it's left open, drag is increased compared with a pusher, from the accelerated flow by the propeller.

Yes, I agree, but it's a lot of fun to fully exposed....So..., I would probably make a removable fairing for the front lower section and a windshield.
At 45 to 60mph, the drag factor is not a huge concern. For me, the ability to use it out in the desert on dirt roads is a major consideration, so this configuration holds up better than a pusher....
Here is a quick sketch of what I am thinking about. It is not to proportion, the front landing gear would be wider to accommodate rough landings
and be more tip resistant. The aft spar to the keel might have a shock strut to absorb the 2 rev. pulses.
The keel tube and wishbone would most likely be carbon fiber/S glass, or kevlar mix.

As far a bucket list, I will probably build it as a 2 seater, but this discussion was about an ultralight, which I think would be possible.
It would also save significant weight to use a Bensen style control bar......