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  #1  
Old 03-27-2005, 05:53 AM
Kumaros's Avatar
Kumaros Kumaros is offline
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Default Pressurized AeroCanard ?

Aside from the bearings of the control linkages through the firewall, the canopy lips, the forward bulkhead, which can or cannot be airtight, and the (redundant in case of a water cooled engine) heat ducts, what other air escape paths are there in an AeroCanard / Cozy?
Would the fuselage structure hold an overpressure of let's say pressurizing to 10 kfeet, while flying at 20 kfeet?
If you've got it (turbo charging, water cooling) why not flaunt it?
I'm sure only an absolute newbie would ask such a question, but I've nothing better to do while awaiting delivery of my plans.
Kumaros
It's all Greek to me
  #2  
Old 03-27-2005, 06:15 AM
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Steve parkins Steve parkins is offline
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i guess there is no harm in me giving my 2 cents here, if you were to wall off the front ahead of the paddles and go up from there then back under the canard you could seal for the hole front. the tubes can get big rubber covers
to still let them move,box in the air brake motor, then i would think a good seal for the canopy can be built.
i wonder if its been done on the cozy ? and i wonder if we could ever use it with 1000 mile range,it mite be over kill and the cozy flys nice when it is lite, all that stuff could add up to some pretty good fuel lose and then we down to 800 mile range, but thats all you get for 2 cents

now pay up.....
  #3  
Old 03-27-2005, 06:40 AM
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Kumaros Kumaros is offline
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Quote:
Originally Posted by Steve parkins
i guess there is no harm in me giving my 2 cents here, if you were to wall off the front ahead of the paddles and go up from there then back under the canard you could seal for the hole front. the tubes can get big rubber covers
to still let them move,box in the air brake motor, then i would think a good seal for the canopy can be built.
i wonder if its been done on the cozy ? and i wonder if we could ever use it with 1000 mile range,it mite be over kill and the cozy flys nice when it is lite, all that stuff could add up to some pretty good fuel lose and then we down to 800 mile range, but thats all you get for 2 cents

now pay up.....
Exactly my thoughts, thank you!
Make the front bulkhead airtight, install an airtight seal around the canopy lips, which they need anyway, judging from other posts about planes taking in water, install some kind of rubber bellows at the area around the passage of control links through the firewall; have I forgotten anything?
I don't see these changes adding any significant weight.
As for the fuel consumption to get to those flight levels, I'm sure it would be more than made up by higher TAS and lower drag at 20 kfeet. Let alone other advantages, like getting over the weather or taking advantage of maybe favorable winds up there.
The real question is: can the fuselage take the pressure?
Kumaros
It's all Greek to me
P.S. Steve IOU a bottle of ouzo and meze (look it up)
  #4  
Old 03-27-2005, 09:59 AM
Marc Zeitlin Marc Zeitlin is offline
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Quote:
Originally Posted by Kumaros
....The real question is: can the fuselage take the pressure?
And the real answer is "NO".

Take the canopy, for a single example. It's 44" wide, and call it 60" long, for ease of calculation. The difference between 10Kft and 20 Kft is approximately 3 PSI. If you want a safety factor of 2, the system will have to be able to withstand a 6 PSI pressure differential. So, 44"x60"x6=15840 lb, or approximately 16,000 lb.

Do you think the standard COZY canopy hinge and latching system can withstand 16,000 lb? I'll guarantee you that it can't, and can't be made to. Do you think that with that much pressure on the canopy, you won't blow the plexiglass right out of the fiberglass frame? The fuselage of the COZY wasn't designed as a pressure vessel. Sealing air leaks is the LEAST of the issues with trying to pressurize it. Remember, the canopy was just one example - there are many others.
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  #5  
Old 03-27-2005, 10:41 AM
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Kumaros Kumaros is offline
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Quote:
Originally Posted by Kumaros
Aside from the bearings of the control linkages through the firewall, the canopy lips, the forward bulkhead, which can or cannot be airtight, and the (redundant in case of a water cooled engine) heat ducts, what other air escape paths are there in an AeroCanard / Cozy?
Would the fuselage structure hold an overpressure of let's say pressurizing to 10 kfeet, while flying at 20 kfeet?
If you've got it (turbo charging, water cooling) why not flaunt it?
I'm sure only an absolute newbie would ask such a question, but I've nothing better to do while awaiting delivery of my plans.
Kumaros
It's all Greek to me
Marc,
thank you very much for shooting me down in flames
That's exactly the explanation I wanted. So, now it's on to oxygen supply systems
Kumaros
It's all Greek to me
Marc, IOU two bottles of ouzo and meze
  #6  
Old 03-28-2005, 06:26 AM
DustinD DustinD is offline
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Like Marc said there is too much force on too many parts. You would end up with a large grenade. Even if it could hold, fatigue would kill it after a very low number of cycles.

Masks, or just a cannula for your altitude, are cheap and easy to do.
  #7  
Old 03-31-2005, 03:44 PM
WestWhisper WestWhisper is offline
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Default Masks

I spotted an add in one of my Private Pilot Magizines--it's an add for a supposedly really nice alternative to an Oxygen mask. Anyway visit Oxymizer.com (I haven't yet) to check this out.
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  #8  
Old 04-04-2005, 02:05 AM
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JonC JonC is offline
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And the theoretical answer is 'yes', the fuselage can hold the pressure.... after you rebuild/redesign almost everything from strake to strake, tail to nose.

However, by the time you got done it would no longer resemble an Aerocanard/Cozy.

You would probably want canopies like a Berkut to allow more support on the plastic (might want to consider something like Lexan).

The current latches would have to go, and you would most likely want to make the canopy close down into the fuselage so that you can use pin style latches into the canopy.

It would be easier to switch to cables for actuation of the control surfaces since they just require a small seal as opposed to a expensive sealing box. Smaller is better when it comes to seals on pressurized aircraft. Smaller seals make smaller leaks when they tear/rip/explode.

All your electric connectors, hydraulic lines, etc need to either be split with sealed connectors on each side of the pressure bulkheads, or they need to be passed through the bulkhead and then the through hole sealed with the wires and lines inside of it. (You better make sure you like how you set up your avionics and so on if you go this route).

You need some sort of pressure control system, most likely mainly pneumatic, so that if you loose power you dont end up overpressurized or dumping all your pressure.

Bleed air is hot on turbos and even hotter on turbines. This is a great feature in the winter, as you don't have to heat the aircraft as much... but in the summer it makes a spamcan sitting in the sun seem cool inside. You will need an air conditioning system.

You have to add fans to your ventilation system, otherwise you wont have flowing air, even then the air that does flow will be recirculated air, aside from the bleed air that is added to compensate for what goes out the outflow valves.

I'm sure that there are a lot of items I am missing. The fact is it would probably be more worthwile to design a new aircraft from the ground up that is meant to be pressurized, as opposed to modifying a current design to incorporate pressurization. You will add a fair amount of weight to the aircraft, you will still on top of all that need an oxygen system (either due to legality, or due to common sense)

All of that just for the comfort of not having your ears pop as much, and to not wear an oxygen mask. I doubt it is worth it.

Also... you should watch a ground pressurization test being done on a certified metal aircraft before you decide you want to build one... it will make you really consider the stresses placed on the airframe.

As a side note... pressurized aircraft are not airtight. Even if you seal the outflow valves, they still leak air, and do so from the factory. They seal the majority of the leaks, but there are still some like drain lines for moisture, etc. You can pressurize the inside of a kitchen strainer if you wanted, as long as you can push more air in than you lose.

~Nathan
 


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