Tall Tails, short tails, horizontals????.....again.....

[skyguynca]

I know these have been discussed probably to death, hopefully I will come up with a question that has not been asked.
I know that a tall tail with a horizontal is too heavy for a true UL gyro. Even the one that was on my 3DRV was pretty heavy compared to the composite T tail for a Bensen or the tube and fabric T tail for a Bensen or the tail for the Hornet or Watson tail for the Gyrobee.

Has anyone done a wood foam fiberglass tall tail? if so what was the weight?
What has been the lightest tall tail? what materials was it made from?

I would like to stick with a tall tail mainly because it pretty much cancelled all torque from the prop, mine for the 3DRV did not have a horizontal though.

I am looking for the best tail for the job but also the lightest one that will do the job.

Thanks for the help.
David

 

[All_In]

P factor torque from the prop can be mitigated by having asymmetrical HS. That means just drop the HS by about 1 inch lower than the HS on the other side. That way you can have a small tail more like Aviomania's which uses this technique to cancel out torque roll. However, Aviomania's are also CLT so that also means Nicolas did not have to add drag with a larger tail to counter pitch changes with power settings.
Carl S. built his rides like that too and his tails were smaller with no torque roll. His was the first gyro I'd seen using this technique.

 

[skyguynca]

thanks for the info, who is Carl S. ?

 

[All_In]

PS:
When Aviomania first came out on the forum Chuck Beaty posted "This is the only modern gyroplane manufacture following all of Juan De Cerva's stability criteria, including CLT and torque roll control" That's from the master so I'd use it.

 

[All_In]

thanks for the info, who is Carl S. ?

I'm dyslexic and could not get spellcheck to spell it for me so put S. Think it spelled SCHNEIDER He's not on the forum

 

[skyguynca]

OK, thanks John

 

[Kevin_Richey]

Dave: Carl Schneider was last on the forum back in April.
His forum name is carls.
I can text him to ask if he will come on to discuss his experiences w/ various tails.

Reading his previous posts on the forum reveals he knows a bit about use of larger props.

 

[skyguynca]

That would be Great! Well if he doesn't mind.

 

[Vance]

P factor torque from the prop can be mitigated by having asymmetrical HS. That means just drop the HS by about 1 inch lower than the HS on the other side. That way you can have a small tail more like Aviomania's which uses this technique to cancel out torque roll. However, Aviomania's are also CLT so that also means Nicolas did not have to add drag with a larger tail to counter pitch changes with power settings.
Carl S. built his rides like that too and his tails were smaller with no torque roll. His was the first gyro I'd seen using this technique.

In a normal gyroplane takeoff with the nose wheel near the ground I have not experienced P factor effect (yaw) from asymmetrical propeller loading in any gyroplane I have flown.

In my opinion the angle of the propeller in relation to the relative airflow is simply not great enough.

I have experienced torque roll opposite the direction of propeller rotation and I suspect this is what Carl was trying to address with his asymmetrical horizontal stabilizer.

Ron Herron also used this on his Little Wing tractor gyroplane.

Ron would put the mains on scales and adjust the left and right horizontal stabilizers until there was no perceptible torque roll.

I have not flown either so I don’t know how well it worked.

Many of the gyroplanes I have flown have power/pitch/yaw coupling.

In my opinion the power/pitch coupling is from the offset of the thrust line in relation to the center of gravity.

In my opinion the power/yaw coupling is from a short vertical stabilizer and rudder with one side of the tail receiving more air than the other because of the swirl given to the air by the propeller.

A taller vertical stabilizer and rudder seem to address this well.

 

[Vance]

I know these have been discussed probably to death, hopefully I will come up with a question that has not been asked.
I know that a tall tail with a horizontal is too heavy for a true UL gyro. Even the one that was on my 3DRV was pretty heavy compared to the composite T tail for a Bensen or the tube and fabric T tail for a Bensen or the tail for the Hornet or Watson tail for the Gyrobee.

Has anyone done a wood foam fiberglass tall tail? if so what was the weight?
What has been the lightest tall tail? what materials was it made from?

I would like to stick with a tall tail mainly because it pretty much cancelled all torque from the prop, mine for the 3DRV did not have a horizontal though.

I am looking for the best tail for the job but also the lightest one that will do the job.

Thanks for the help.
David

Good morning David,

I spent some time with constructing empennages from different materials (carbon fiber, fiberglass, aluminum with ribs, tube and fabric) and the lightest appeared to be thin aluminum sheet with ribs.

Tube and fabric was a close second.

As a youth I had built surf boards with shaped foam and fiberglass with wood stringers so I particularly wanted to try this method. It was not as light as aluminum sheet or tube and fabric.

I was advised by Martin Hollmann of Aircraft Designs to use a layer of fiberglass with a carbon fiber empennage because carbon fiber by itself tends to be impact sensitive. This ended up being the heaviest construction. Martin was a composite airplane designer and gyroplane enthusiast.

Martin designed a straight fiberglass empennage that in the calculation was lighter than carbon fiber. It was never built.

 

[giro5]

If you had one made of tube and fabric, one of aluminum sheet and ribs, and one with fiberglass over foam and laid them down and stepped on them only the fiberglass over foam would not be damaged.

 

[Doug Riley]

Different materials have different properties. It's normal for a given material to perform well with respect to one property and poorly with respect to another.

An aircraft tail is not asked to endure random point-loading, so the fact that a glass-and-foam tail may survive being stepped on is irrelevant. "Step-on resistance" IS required of surfboards, ladders and the like.

An aircraft tail OTOH is required to be stiff in bending and torsion, and to endure both vibration and relatively large DISTRIBUTED loads, at the least possible weight.

A key to saving weight is to put the skin of the device to work as the main load-bearing member. A tube-and-rag structure is inefficient under this analysis; the fabric adds negligible stiffness or beam strength. It just guides the air around.

Stressed-skin structures are more efficient as tail surfaces. These can be of bent plywood skins with ribs and spars (not Bensen's slab-plywood method), glass-resin-and-foam, or formed thin sheet metal (again not using the Bensen slab method, but rather ribs and spars with a formed skin).

Glass and foam structures on homebuilt aircraft seem to lack weight-efficiency because (1) they are generally more resin-rich than necessary, owing to simple "paintbrush" construction, (2) fiberglass is strong in the sense that it doesn't rupture easily, but it's extremely limber and (3) you have to fill the cloth weave with some sort of glop, which adds weight without strength. As to #2, we want stiffness, and we end up adding cloth to get it (that is, our structure ends up too strong from the actual breaking-strength view point because it otherwise would be too limber).

At any rate, Cessna-style thin aluminum skins, ribs and spars can result in a tail that's a few pounds lighter than an equivalent foam-and-glass job. Or so I've found when I've replaced a 'glass tail with ribs-and-sheet-metal tail on a couple gyros. On a small gyro, you usually can save 3-5 pounds going from composite to sheet metal. I've experienced this on a Butterfly that a friend converted to a Dominator tall tail, and on my own Gyrobee.

Helpfully, thin aluminum-alloy sheet naturally bends into a shape that's close to an airfoil section if you pre-bend the leading edge radius. And it's already smooth, eliminating the tedious sanding and heavy filling.

Just paste a couple "no step" stickers on your metal tail.

 

[C. Beaty]

Carl Schneider isn’t one to accept “strange” theories without question. When the discussions began about CLT, Carl added a second keel to his gyro on which the pilot was seated that could be slid up and down to change CG location. Carl said the higher it got, the more stable the gyro became. (probably wouldn’t go high enough to become LTL)

 

[giro5]

Doug I think Burt Rutan would disagree with you about the utility of using fiberglass over foam. From the VariEze, Long-EZ, Quickie, Dragonfly to the Voyager none are built with aluminum skins. Put your aluminum skinned anything in some hail and see what happens.

 

[giro5]

Building the Rutan Composites is available on CD but it must be several generations of copying because the quality is poor but anyone wanting to build using fiberglass over foam should view it if for nothing else to see the technique of how to not use too much resin in making your pieces. And to see Burt stepping on an aluminum wing and his foam/fiberglass one.

 

[JETLAG03]

This is what I did. T Tail design. Styrofoam and fiberglass. Same process to make a surf board. Sun cured resin. 16.5lbs total.

https://www.facebook.com/video.php?v=703204667285377

Video unavailable

 

[DarDow101]

This is what I did. T Tail design. Styrofoam and fiberglass. Same process to make a surf board. Sun cured resin. 16.5lbs total.

 

[Jean Claude]

the right questions are :
- would it be possible to build it with less carbon layers layers ?
- how much weight would we save using a vacuum bag to get rid of some of the resin ?

1° The dynamic pressure is concentrated on the front quarter of the chord. Why use a uniform thickness of carbon along the chord?

2° The bending moment in the soles (skins?) decreases from the root and cancels at the tip. Why use a uniform thickness of carbon along the span?

3° The stress in the soles (skins) would be reduced if the thickness of the profile is increased. Why choose a 12% profile,when a thickness of 17% would be more advantageous.

Using the material only where it is needed is the art of light construction. Remember that the control surfaces of the DOUGLAS DC3 were not covered with aluminum, but just with stretched canvas.

 

[C. Beaty]

we have an " Hey Chuck Case" hahaha please please chuck

Sorry, JM, I am not a fiberglass/foam person; too labor intensive.
Having access to structural bonding facilities for aluminum, I’ve always built control surfaces using 0.020’ (0.5 mm) 2024 aluminum; often with corrugated paper board for ribs. The paper board was cut into slightly oversize rectangles, dipped in a dilute solution of polyester resin, hung up to dry and cure, then stacked and sawed to shape leaving a fresh edge for epoxy bonding. Usually without a spar when supported from both ends and with aluminum end caps.

 

[Doug Riley]

Dar Dow, your tail group's weight is is just what the (similar) Watson tail on the Gyrobee weighs.

Rutan certainly worked hard to get the weight of his composite structures down. Paintbrushes come into liberal use in "stippling" to get out the air bubbles and avoid dry spots. He also advocated the use of a plastic squeegee to skim off excess resin, as well as the use of light fillers.

The fact remains that you have to fill the cloth weave with SOMETHING to achieve a smooth airfoil surface, and that "something" inevitably adds weight without adding strength or stiffness.

I imagine that sophisticated carbon-fiber construction can at least equal sheet-metal in weight/strength efficiency. But "sophisticated" means using prepreg sheets, vacuum bags and very careful placement of the fiber. My point was that homebuilt composites are likely to be heavier than homebuilt sheet-metal jobs. At least that's been my experience.