Baggage tubes

[Battson]

Hi everyone, a friend is building a Bearhawk and wanted advice on how to do a baggage tube. I was surprised to hear that the forum hasn't covered this yet. Unless there's a thread which has been missed, would anyone care to share their designs and building experience?

Specifically we wanted to know about the construction technique, dimensions, weight of the tube itself, CG impacts of the tube, and max design load are of interest.

[svyolo]

It might be difficult to standardize. I only want to carry fishing rods and maybe a paddle. Somebody living very remotely might want to carry building materials. Totally different. I think tension members supporting it above and below would be lighter than just from one side.

A couple of the overpriced Super Cub types have some pretty slick cargo options aft of the cargo bulkhead. Doesn't make them worth 300k IMHO, but interesting non the less. Especially with a nose heavy airplane that I am building.

[Mark Goldberg]

I have seen some light weight composite tubes of maybe 8" diameter run aft of the cargo area. The tube itself was very light and only long, light items should go back there. Mark

[Mark Moyle]

I’ve been looking for schedule 10 plastic pipe of some sort for just that....can’t find it?

[Steve W]

If you want it for rods and paddles make a sock of appropriate weight and suspend it in back away from the sides and bottom.

[svyolo]

I hadn't thought about a sock, but that sounds good as well. If you want a tube, just roll one. Use a thin flat plate of something - aluminum, very thin aircraft plywood, fiberglass, etc. .015 aluminum should be fine, The round shape gives it lots of stiffness. Put a round former in the inside to form a bottom, One external former up at the bulkhead. If is longer than 3 ft, put another external former in the middle. I don't have any .015 al, but lots of epoxy and cloth. I will laminate a flat sheet of something, and roll it. It will be as wide as my widest kayak or SUP paddle. 7 or 8 inches. AL might be the least work, and we all have the tools and hardware.

I would suspend it on the aft end with tension members of some kind, either 2 on top and 1 on the bottom, or 2 top and bottom. 4.5 G's at 5 pounds isn't much.

[JimParker256]

"4.5 G's at 5 lbs isn't much." True, but that's the g-loading for in-flight stuff. What you're worried about is a crash, where that paddle is thrown forward because of a high-G horizontal impact. Now you've got a 5-lb spear aimed your head / shoulders that's still moving at whatever speed you had when you impacted. But given the slow stall speeds of the Bearhawk line, I'm not sure how big of a deal this really is... In any case, I would put more solid "structural support" at the front end, where it would also serve to keep the tube "capped" during an incident.

[svyolo]

I will have something keeping them from flying forward. Maybe a small piece of netting over the opening.