Anyone know a good way to make a belly baggage pod?

"Tedstriker" wrote

A dirigble can produce some lift due to it's size, the air would
have so far to travel to get to the top to neutralize the low pressure
up there.

Incorrect. The reason the dirigble has noticible lift is not how far the
air has to travel, but has to do with pure size, (area) and also the
Reynolds Number effect. Larger would measure more lift per square foot than
the smaller per square foot due to the multiplier of the Reynolds Number in
the equation.

But on 13" diameter cylinder, any lift produced would be so
insignificant, as to be barely measurable.

True, it would be barely measurable, but it would be measurable, *if* you
wanted to do it.
--
Jim in NC

On Tue, 14 Jun 2005 23:32:34 -0400, "Morgans"
wrote:


"Tedstriker" wrote

A dirigble can produce some lift due to it's size, the air would
have so far to travel to get to the top to neutralize the low pressure
up there.

Incorrect. The reason the dirigble has noticible lift is not how far the
air has to travel, but has to do with pure size, (area) and also the
Reynolds Number effect. Larger would measure more lift per square foot than
the smaller per square foot due to the multiplier of the Reynolds Number in
the equation.

But on 13" diameter cylinder, any lift produced would be so
insignificant, as to be barely measurable.

True, it would be barely measurable, but it would be measurable, *if* you
wanted to do it.

agreed, I should have mentioned reynolds number.
I am inverting the baggage pod, so the more curved portion is in the
bottom. And a comment was made that it would produce lift in the wrong
direction. But the amount of that should be so small as to make
insignificant difference.
Another thing comes to mind, and that is the ability of the pod to
absorb shock in a forced landing with the gear up. Most high
performance tailwheel airplanes are recommended to land gear up in an
off airport, forced landing, to reduce the possibility of a nose over.
But I just remembered watching the "Wings of the Luftwaffe" series
about the ME 163 Komet, that landed on a skid that was equipped with a
shock absorber. And in every case where the skid did not extend, the
piltot suffered severe back injuries to the spine, from the shock of
sliding along the ground. In my plane, there is only inches of space
between the pilots seat, and the belly with the gear up, and in a
forced landing, with gear up in a field, I would expect to probably be
subjected to similar types of shocks and back injuries. Very painful.
The only shock absorber I have is the foam in the seat cushion. So I
am thinking that the belly pod should be reinforced to possibly
provide some shock absorbing ability. Couldn't hurt. My plane lands
around 80mph, stalls at 65. So I'd be initially sliding along at a
good clip. Add to that going over rows of plowed ground. It could be
very violent. And most fields look smooth as a carpet from the air,
and it's only when you are so low as to make landing elsewhere
impossible, that you can see what the field conditions really are.

"Tedstriker" wrote

The only shock absorber I have is the foam in the seat cushion. So I
am thinking that the belly pod should be reinforced to possibly
provide some shock absorbing ability. Couldn't hurt.

Remember that parts tearing off, also removes energy. I'm not so sure that
I wouldn't design it to break away, after some reasonable stress.

Is it possible to put some closed cell Styrofoam (like cheap ice chests)
between your seat foam and the floor? That is what is in motorcycle
helmets.

I agree with your assessment that the pod up or down isn't a significant
issue. Personally, I would go with what looks best.
--
Jim in NC

On Wed, 15 Jun 2005 22:55:44 -0400, "Morgans"
wrote:


"Tedstriker" wrote

The only shock absorber I have is the foam in the seat cushion. So I
am thinking that the belly pod should be reinforced to possibly
provide some shock absorbing ability. Couldn't hurt.

Remember that parts tearing off, also removes energy. I'm not so sure that
I wouldn't design it to break away, after some reasonable stress.

Is it possible to put some closed cell Styrofoam (like cheap ice chests)
between your seat foam and the floor? That is what is in motorcycle
helmets.

I agree with your assessment that the pod up or down isn't a significant
issue. Personally, I would go with what looks best.

Yes, and the pod that is designed for the eze's is better inverted on
my plane's belly, as that way the pod's tail has an upsweep, and
better ground clearance in the 3-point attitude.
I may in fact have room to put some closed cell foam under the pilots
seat. And if so, I'll put some in there. I forgot to mention, the
pilot's seat is a canvas sling-type attached to a 4130 steel frame. So
that would probably stretch and provide some additional cushioning, if
it didn't tear. If that happened, that would be the time to have the
foam underneath.
The break away idea sounds reasonable, so I won't get carried away
making it too strong. If it were, I would assume it would transfer
stress to other areas of the airframe, causing other failures.

In article ,
"Montblack" wrote:

("Thomas O'Grady" wrote)
[snip]
I have a pod on my Cessna 206. It comes to a point on the front, but
the sides and bottom are all flat sheets and the corners have very
little radius, maybe 1 inch. It wraps up the side of the fuselage about
4 inches, so the bottom is actually flatter than the original. It is
less than 8 inches behind the exhaust.


What's the approx size of your pod L-W-D?
(...forget the ends if that's an easier est. g)

How do you access it?

What did it cost in performance numbers before-and-after? Noticeable?

Oh, what's the back of your pod look like?

Thanks.


Montblack

Useable about 40 inches W x 70 inches L x 9 inches D, overall 96 inches L
10 inches H x 27 inches W door on side.
Book says 5 to 8 mph and 50 fpm climb
Width tapers from 40 inches at 60 inches back to 30 inches at 84 inches
to 20 at end. Bottom is flat and curves up to meet the fuselage.
Book says "designed to accommodate three 'two-suiters' plus misc"