Cargo pod

[Gerhard Rieger]

Hi all you Bearhawk builders out there, I like to get your opinion on adding a cargo pod to the Bearhawk 260hp to move all the heavy stuff to underneath the pilot and the lighter stuff in the back and to keep the C/G from moving to far back especially on bush strips.

[whee]

My BH will have a fiberglass belly pod on it. It will run from station C/S to F/L and be fat in the front and thin in the rear just like many certified belly pods. I welded in float fittings at station E/M and will have a strap there and at the rear gear leg attachment. I'll probably put a strap at station D/N also because I want the pod to be good for 400lbs but it will be a clamp that goes on the longeron like many other pods use. It will be much like the Firman Pod for cubs. Fat enough for 5gal gas cans in the front.

Firman Pod:

[Launchie]

Whee have you done a drawing or design for your pod yet?

[Battson]

You may already have seen this?

[Launchie]

Did you do a drawing for your cargo pod?

[LukeS]

That doesn't look very aerodynamic. I wonder what kind of performance loss a pod like that creates? I would suspect even a clone of the Firman pod would create noticeable performance losses on a plane that would typically fly faster than any Supercub. Whee, if you go through with the pod, please share some before/after data with the group.
Thanks

[Battson]

In a Skywagon, from memory I understand they cost around about 10 knots. But I don't know. The Bearhawk is a fairly similar aircraft, in terms of performance.

[LukeS]

If a pod like this could be had for only a ten knot loss, I'd be hooked!

[Zzz]

Here's a police sketch artist's rendering of what a bush plane criminal might design for a belly pod. I think one would have to go carbon fiber with a custom mold.



Of course there's the little problem of the oleo struts... Cub gear cabane is quite forward and clears the front of the pod. I suppose it has to be more aft on a BH.

[Battson]

Annoyingly, the pod would have to stop at the rear gear leg attach fitting, there are shock struts in the way.

[Battson]

You could fit that dog in there... funny story about that for another day...

If someone makes I mould, they would surely cover the costs by selling a few pods.
The trick is to come up with an easy and universal way of attaching them to any machine, completed or WIP, without major modifications.

[Zzz]

So how is that accomplished with Super Cubs? Probably some fabric patching involved.

[Battson]

The trick is, where you really want the weight - under the wing spars / front seats - is where the landing gear shock struts are.

There's typically barrels of room in the back, 9 out of 10 times it's just a CG issue which makes the pod attractive.

It would be easy enough to attach a pod using adel clamps to bolt clips onto the longerons. Just a handful of patches to apply.

[Zzz]

Here's how the Aviat Husky pod looks:

[whee]

Still quite a ways out but I'm thinking about the belly pod I'll be building for my BH and I'm wondering if it should have a top on it. The Firman pod didn't have a top till the FAA told the designer they wouldn't approve the STC till he added a top. My impression is that the guy really didn't want to add the top and never did add it to the pod he had on his personal plane. Leaving it off saves some weight but then the belly fabric doesn't have any protection.

Also, think doors are needed on both sides? I'm thinking not really, might be convenient but not really needed and will add weight. Need a door on the aft end though to load skis/snowboards.

I ended up welding on a tab for the center strap on the pod. Three straps to hold the pod on that attach at the rear gear mount, the welded on tab and the float fittings.
Untitled by Jon Whee, on Flickr

[Battson]

I looked into a pod extensively after we had this discussion in 2015. I am sad to say, I don't think they make sense in a Bearhawk 4-place, even with the biggest engine installed.

The problem is you cannot put a pod far enough forward to keep the plane balanced. Let me explain:

My CG is now forward of the front limit, before I add fuel and a pilot. So I have lots of room to work with.
As I add more and more gear and people, the CG moves back until it reaches the aft limit.
When I get to aft CG limit, in every case I always have room left inside the fuselage. It's the combined location and weight of the goods which cause the problem.
Adding a pod would help address that problem, IF it were far enough forward. In other words, the largest part of the pod needs to be under the wing - even partially forward of the wing when in level flight. That's where you see the big pods location on an A185F for instance:


But on a Bearhawk there are shock struts in the way, so you can't put a pod that far forward. In fact, the main landing gear shock struts attach so far back, that almost the whole pod is behind the CP of the wing. Consequently, installing even the lightest pod makes the CG problem worse. Before you even stow any gear into the fuselage, by attaching a pod you've further limited your ability to load gear into the plane. Now - that might not hold true if you are carting feather dusters or pillows - but for things aboard like passengers, personal effects, luggage, camping gear, firewood, equipment, in fact most any typical mix of cargo I have carried - you reach the aft CG limits before you run out of room inside the fuselage. Even if you made a custom pod to fit around the shock struts, as some have suggested before - then you can't put anything inside the pod in that area - which is all that really matters, the cargo inside not the pod itself.

Overall, I think the right solution to carrying more in a Bearhawk is forward stowage of heavy items, and packing the fuselage to the roof.

[whee]

I too have recognized the limited usefulness of a pod on a BH because of the reasons you mention. However, in my case I'll have almost zero room in the cabin for baggage; I'll have three rows of seating so I need somewhere to put the baggage.

[Battson]

I too have recognized the limited usefulness of a pod on a BH because of the reasons you mention. However, in my case I'll have almost zero room in the cabin for baggage; I'll have three rows of seating so I need somewhere to put the baggage.

Yes - that usage case I can understand perfectly - you can't stack baggage on top of or around children in car seats. Those car seats are huge these days. That is one of the few cases (like hauling pillows or feather dusters) where you run out of room inside the BH.

I have run the CG numbers with three rows of seating, and I can't take any meaningful baggage unless all the passengers are children or very light adults.

[Zzz]

Those car seats are huge these days. .

I recent purchased a car seat to be used exclusively for flying and air travel because of its light weight. The convertible we use in the car must weight 30 pounds, I swear, but this one weighs like 6 lbs. It's pretty Spartan, but it's comfortable and does the job of being a restraint that's ergonomically geared for little bodies.

https://www.walmart.com/ip/Cosco-Scenera-NEXT-Convertible-Car-Seat-Choose-your-Color/41126745?action=product_interest&action_type=title&item_id=41126745&placement_id=irs-302-m3&strategy=PWVUB&visitor_id&category=&client_guid=57e667e1-16f2-4745-aed4-53b7479508e5&customer_id_enc&config_id=302&parent_item_id=41126739&parent_anchor_item_id=41126739&guid=c4cb15de-1a13-4881-9eab-5f1fd4d77375&bucket_id=irsbucketdefault&beacon_version=1.0.1&findingMethod=p13n