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#31
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"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 |
#32
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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. |
#33
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"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 |
#34
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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. |
#35
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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" |
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