Tail Boom design

[Terry]

I am really impressed with Chuck's gyroplane. The layout looks to be all business.

But that tail boom is ugly. In fact, all pusher gyroplanes look like an afterthought, a collage of parts hastily and handily thrown together. No offense intended, most simply look like an erector set project.

So, what about a tail boom that exits through a combined reduction sheave and propeller hub? The boom could double as the engine mount and shaft for the propeller hub and sheave.

Has anyone tried something like this?

Imagine Chuck's clean, lean CLT idea with a two inch diameter, quarter inch wall 2024 tube extending far enough through the hub, past the prop to mount a tail boom. All this with the control cables running through the tube. Looking at Chuck's current propeller, it doesn't look like it would be too difficult to adapt some of the hub parts and blades to a larger hub and bearing.

Just some ideas on topic.

[Passin' Thru]

So, what about a tail boom that exits through a combined reduction sheave and propeller hub? The boom could double as the engine mount and shaft for the propeller hub and sheave.

Has anyone tried something like this?

Terry, there is someone who visits the forum who is building one just like that. I can't remember his name or find the threads but he posted pictures. Anyone remember?

[RotoPlane]

Yeah, I remember that one too. I tried to find the post, but I seem to have an inability to make the forum search find anything.......

[RotoPlane]

I was thinking along the same lines as you Terry, but I am building a UL and the extra weight put a stop to that idea. Also it is not a simple design, not to mention the high cost for large bearings.

Chucks tail boom is…..distinctive….it grows on you. It also is a good way to use a large diameter prop and still have CLT. Granted, the vertical stab could use some different lines ;).

[dinoa]

I saw one in an article about the "Bois" gyro round up in France some years back but cant remember the publication (It may have been an English PFA magazine). Maybe one of the French members can help.

Dino

[PW_Plack]

I've doodled something like that, but I have no idea what it would take to make the prop hub work. My thought was to use a belt reduction drive from an engine mounted atop the outer tube, and be able to pull a couple pins and quickly detach everything aft of the prop by sliding out the tail boom. (Which would also be necessary to change the belt.)

Most of the compromises we see in gyroplane designs are made to reduce cost or make for simpler construction. I've been interested in compromises that would allow low manufacturing costs and ease of transport and shipment. I'd love to see a way to allow carrying the machine in a six-foot pickup truck bed with minimal overhang. A removable, coaxial tail boom would help, and when removed would also allow a very steep departure angle without a vertical stab, rudder and tailwheel dragging on the ground during ramp loading.

[phantom]

I did one years ago and it is not as simple as it seems at first glance. My first attempt was to simply put bearings on the boom, this led to vibration and cracking problems. the only thing that worked after much wasted time and metal was that I happened to have a compleat nose wheel from, I think it was a PBY and the axel was hollow and big enough for the boom to pass through without touching, this was mounted on the bottom of a 640 rotax and the whole thing was mounted to the mast on rubber mounts, a peice of rubber hose was pressed into the bore to prevent boom damage on rough ground as the engine and redrive could move around quite a bit. What did I gain? a funny looking machine that weighed about 50 pounds heavier than my previous funny looking machine.

[Terry]

I've doodled something like that, but I have no idea what it would take to make the prop hub work. My thought was to use a belt reduction drive from an engine mounted atop the outer tube, and be able to pull a couple pins and quickly detach everything aft of the prop by sliding out the tail boom. (Which would also be necessary to change the belt.)

Most of the compromises we see in gyroplane designs are made to reduce cost or make for simpler construction. I've been interested in compromises that would allow low manufacturing costs and ease of transport and shipment. I'd love to see a way to allow carrying the machine in a six-foot pickup truck bed with minimal overhang. A removable, coaxial tail boom would help, and when removed would also allow a very steep departure angle without a vertical stab, rudder and tailwheel dragging on the ground during ramp loading.

I suppose the biggest problem with the idea of a tail boom extending from the engine/drive unit would be vibration damping. Maybe it's an idea before its time.

[Alan_Cheatham]

Here ya go guys, link to former thread on this subject:

http://www.rotaryforum.com/forum/showthread.php?t=14869

[RotoPlane]

I thought I deleted this, but it was on my back-up drive. The tail controls went through the 3" boom. The driven pulley and tail boom assembly are solid to the frame. A spring-loaded belt idler keeps the belts tight as the engine moves around. I was going to use WarpDrive blades and make my own split hub that bolts to the pulley. I think this would work, but it is too heavy for my UL. The spacer and nut that holds the bearings is not shown.

[All_In]

Terry, there is someone who visits the forum who is building one just like that. I can't remember his name or find the threads but he posted pictures. Anyone remember?

@Terry
More info:

It was her name and she only posted once with a picture. She had a unquiet cabin too! I did search for it as I did respond but I talk to much and can't find her post!

@Ed
That looks very similar to what she must have done. It was a very cool looking design I wish I could find the post for you to see!

[Passin' Thru]

Here it is! http://www.rotaryforum.com/forum/showthread.php?t=20191

John, the builder's name is Dana, but that don't mean nuttin'. :)

[All_In]

Thank you Pete! I PM'ed her (I think) and when she responded I found out he was a she!

PS
I don't remember exactly, but I do remember being surprised that he as a she!

[RotoPlane]

Yeah Pete.…I think that is the one I remember. This is making me re-think the boom thing…..dumb it!

BTW….Dana is a guy; he had a wife at one time.

[Terry]

Thank you Pete! I PM'ed her (I think) and when she responded I found out he was a she!

PS
I don't remember exactly, but I do remember being surprised that he as a she!

I even posted on that thread and had forgotten about it in four months.

[All_In]

Yeah Pete.…I think that is the one I remember. This is making me re-think the boom thing…..dumb it!

BTW….Dana is a guy; he had a wife at one time.
Thank you Ed for straightening me out on my confusion too.
I'd like to see and hear how it turned out!

[RotoPlane]

Just for the halibut, I thought I'd see what this tail boom through the prop would look like.

Made a few changes to make it work on my gyro design….you can zoom in to about 800%…..

[Terry]

Just for the halibut, I thought I'd see what this tail boom through the prop would look like.

Made a few changes to make it work on my gyro design….you can zoom in to about 800%…..

That's some nice work. Did you do that today?

As I think more about it, seems like the driven pulley would need to be mounted on its own concentric tube shaft, with the boom in turn passing through in isolation; either with rubber or air cushioning. Otherwise the engine vibration would translate to the boom, or the belt would not be under fixed tension and alignment.

[RotoPlane]

Did you do that today?

Just the new tail boom part.

It's probably difficult to see Terry, but the tail boom and its support tube are fixed in relation to the frame. The bearings and pulley ride on the tail boom support tube. The engine rides on its rubber dampened mounts. A spring loaded idler pulley keeps the belts tensioned. So the tail boom has no more vibration than the airframe.

[Terry]

Just the new tail boom part.

It's probably difficult to see Terry, but the tail boom and its support tube are fixed in relation to the frame. The bearings and pulley ride on the tail boom support tube. The engine rides on its rubber dampened mounts. A spring loaded idler pulley keeps the belts tensioned. So the tail boom has no more vibration than the airframe.

Velly intelesting. Can you do that with belts and tensioners? That would pre-load the engine mounts with the belt tension.

[RotoPlane]

Yes, I think so. The FWD engine mounts would be adjusted to keep the pulley's in alignment when the correct tension is applied. Because of the wide engine mounts locations, the engine will not move very much anyway. I would do this but I unfortunately, so far, I cannot find a way to run my pre-rotator assembly the way I want to…..no place to put the 4" P.D. driver pulley under the engine.

[PW_Plack]

Ed, the drawing is neat, but have you anticipated the leverage that far aft tailwheel would have on the boom attachment point, especially during landings? Is there bracing not shown?

Also, why lose the spinner? It would be straightforward to mount some aerodynamic enhancements aft of the prop on the boom to smooth the flow. They could certainly be made light enough to be a non-factor for stressing the boom. (Although the "spinner" would no longer actually "spin...")

[RotoPlane]

Actually Paul, I didn't think of using a spinner that didn't spin. It would need to slide aft so the boom attach bolts could be removed and it would enhance the appearance….and perhaps lessen drag….a bit. As to the stress at the boom attach point….I didn't take the time to run the numbers, but I believe it would be okay. The boom is 3" O.D. X .125 wall, 6061-T6 tube and it slides 5" on to the support tube and is secured with four 5/16" bolts (each through one wall into a riv-nut). The 6061-T6 support tube has a 3/8" wall in the bearing area and 1/4" wall for the other areas. The support tube is attached to the frame uprights and to the rigid portion of the engine mounts. Would it break?.....oh, I hope not…..

[choppergabor]

That's a neat design Ed. I really like the strength of the structure. It sure gives a massive built impression. :)

[RotoPlane]

Yes....it does look rather massive. But >98% of the airframe volume is foam....the S2 glass however, does make it very strong, without a bunch of bolts.