Any interest in a cargo pod?

[whee]

Thanks for the conversation guys. I met with the composites outfit I mentioned and they determined that without half a dozen or so seriously interested people that it wasn't a project that could be done with their involvement at a reasonable cost. The guy was pretty cool, offered some ideas and said he would provide me some guidance that would help me get a one-off pod made. With the lack of interest in a pod for a BH4 or BH5 I plan to go the one-off route.

I collected the dimensions of the Patrol and the BH5 so I could determine sizing. Thanks to you guys that helped me out with those numbers. The pod I am going to make for my airplane would be suitably sized to work on BH5 but will not work on a Patrol.

My suggestion for you Patrol guys is to contact Randy Apling at Carbon Concepts or Bob Piatt at Alaska Bush Pod (Firmin Pod). Both outfits have pods that can be easily modified to fit the Patrol. Personally I would go with the PA-12 pod from Bob Piatt unless I could convince him to modify his PA-18 Jumbo pod which would be awesome.

Andy, I'll send you a PM so we can connect and compare notes.

I think I have the size and basic shape nailed down so once I clear some projects I'll start building a plug. The mounting is pretty easy since I'll do the same as most of the other outfits do; stainless steel straps with clamps around the longerons or tabs welded to them. Bill Firmin tested his original PA-12 pod to 600lbs and it was light weight, 12lbs, and only had 2 straps around it so I should be able to achieve my design goals pretty easily.

Thanks again guys!

[Bcone1381]

I’m real excited to see you take this project on, Jon. Please Keep us informed on how it goes.

[Chewie]

Aww, there goes my friends and family discount! But thanks for the inspiration. I do like the concept of loading up to gross with more control of the CG using a pod.

[svyolo]

Whee, you scratch built a Bearhawk. Building composites is childsplay compared to that. Building boats, composites is almost unskilled labor. Above that level, vacuum bagging is very easy, even though I have never done it. Resin infusion, where you vacuum bag dry fabric while infusing resin, probably takes a bit of experience. For me, I am only making one part. The labor involved in making one part rarely makes vacuum bagging or resin infusion viable. That is why I have never done it, despite the fact that it is better.

I am not set up to grind CF safely. For that reason, I only want to use CF in a situation where I don't have to grind on CF. Nicely female molded CF, OK. If I have to do surface prep, fiberglass only, which I also hate doing. I have ground and sanded way too much fiberglass. I hated it. CF scares me.

[whee]

Thought I'd give you guy a little update. I drew up a few more concepts and settled on a configuration. We then built some of the wood "formers" we will use to guide the forming of the plug. The thing is pretty massive, equivalent volume of 175 US gallons, but the current dimensions are what make sense when fitting it to a BH. It might be too big but we shall see.

cargo pod_iso.jpg

cargo pod_lower_iso.jpg

[Battson]

Should it have a faired shape at the back to improve aerodynamics?

I understand the Skywagon pod costs around 8 to 10 knots, although they are fairly streamlined.

[whee]

Battson, maybe. The Cessna is a cleaner airframe than the BH and it’s pod is even more massive; basically 108”x36”x18”. My concept comes from the Firmin pod which many Cub guys claim increases their speed a couple knots or at least doesn’t cost any. That is likely from the pod cleaning up the air behind the gear. The BH is in between a Cub and a Cessna so I’m not sure how critical the shape is. My feeling is that it’s going to cost me a few knots but the shape of the back isn’t going to make a measurable difference.

I certainly open to suggestions on that front. I just want to be sure there is a rear door.

[500AGL]

The trailing shape will make a greater impact on drag than the frontal area. I’d recommend spending a minute on it.
As you mentioned and I believe to be true, the cubs with pods are faster only because they clean up the cabane airflow.

“It might be too big but we shall see” said no man ever. Even when referring to a cargo pod.

[500AGL]

One other note. If you ever strap an aluminum boat to the struts of a float plane with the bow pointed forward and square stern facing the tail…
…. If you make it back to the water still in control of the airplane you’ll never strap it on in that direction again.

[whee]

I completely agree. However, the design constraints being what they are and my lack of ability to do any computational analysis somethings won’t be known until testing is done.

The key constraints frustrating the design of an ideal trailing shape are:

1. Interior must have 200cm of usable length. My touring skis must fit without angling them or pushing the door closed on them.
2. There must be a rear door.
3. The external length must be as sort as possible so as to not further compromise the empty CG.

The better trailing shapes I came up with resulted in a pod that was at least 9 feet long and were challenging to put a door in.

It does not look like it in the pictures but the current shape has a shallower trailing angle than the Firmin pod. The views I posted make it look vertical.

I’m still fiddling and am thinking I can reduce the trailing wake by making tail shallower with a bit more angle. But I can’t make it well faired like a Kodiak or King Air pod.

[500AGL]

Maybe you can do a stubby taper and then hinge the entire taper. Or double door it like the back of an MBB helicopter.

[whee]

Maybe you can do a stubby taper and then hinge the entire taper. Or double door it like the back of an MBB helicopter.

There is a pod that hinges the whole rear section but I do not like how it looks and I think it would be hard to keep water out.

I did a little thinking and fiddling and came up with this. I'm not thrilled with it but it would work. The volume decreased from 176 gallons to 146 gallons. That is significant but is probably still plenty big.

cargo pod_drw.jpg

[500AGL]

Jon, what’s the door system in that concept?

[whee]

Jon, what’s the door system in that concept?

Side door is the same, approx 12” x 30”. The rear door would be approx 18” tall and 12” wide. The rear door would only open half of the back of the pod. This allows you to put the skis inside then move them over where they would rest against the rear portion of the pod that does not open.

[svyolo]

Whee, are you trying to carry long and skinny, or bulky?

[whee]

Both. With 3 rows of seating there is almost zero room for cargo in the cabin of my airplane with the family loaded. Almost everything will have to go in the pod. Those loads will be mostly bulky. Once the plane is on skis I hope to use it for backcountry ski trips which will require loading my alpine touring skis, some extra fuel and a generator for preheating the airplane.

[500AGL]

Jon, I can get pics if you want but I’m sure you’ve seen them all.
Was just at breakfast with two different pods, which reminded me that while not tall, the tails are not as long as recalled. If you match the front and back it would be about the same. The production units just don’t have too much sidewall curve, but hold a similar vertical curve. If that makes sense. The rear door is curved.