What is this?

[JOhnH]

What is the thing behind the antennae on the top of the fuselage?
My first guess was an air horn, but I was told it is an air scoop. What needs air back there?

 

[G-Man]

Fresh air for coach class passengers?

 

[gkainz]

a/c intake?

 

[SixPapaCharlie]

I know a guy w/ an older bo and he has something similar
He said you dump ice in there (had a hinge that opened and closed) and it blows cool air on the pax.

 

[DJTorrente]

I know a guy w/ an older bo and he has something similar
He said you dump ice in there (had a hinge that opened and closed) and it blows cool air on the pax.

What happened to the water after the ice melts?

 

[SixPapaCharlie]

I don't know he told me he never used it.
He might have been messing with me.

 

[KSMooniac]

Could be the intake for overhead vents?

1978+ Mooneys use a NACA scoop on the dorsal fairing to do that task. The air is turned 180 degrees and flows forward to the overhead eye ball vents. It works better and is less drag compared to the original Mooney pop-up scoop.

 

[SCCutler]

That's just the air intake for the fresh air that comes out of overhead vents; it became standard on the V-Tails in (IIRC) 1967 - ish. My '69 has it.

 

[Let'sgoflying!]

My friend had an older model bo and he also claimed his could be filled with ice, and this would drive air past the ice, over the occupants.

 

[mondtster]

I believe they are for the swamp cooler option. Mine doesn't have it nor do any of the other Beeches in this area that I've been around.

 

[SixPapaCharlie]

My friend had an older model bo and he also claimed his could be filled with ice, and this would drive air past the ice, over the occupants.

I see you are in Texas.
Maybe it was the same friend

Brings up a good question, How does the air get separated from the melting water? Maybe ice just pools in some sort of coils and air blows over them. No idea.

 

[alexgeo]

http://www.vintagebonanza.com/air_conditioner.htm

 

[Henning]

My friend had an older model bo and he also claimed his could be filled with ice, and this would drive air past the ice, over the occupants.

You don't use ice, you use water, it's an evaporative cooler.

 

[Henning]

I see you are in Texas.
Maybe it was the same friend

Brings up a good question, How does the air get separated from the melting water? Maybe ice just pools in some sort of coils and air blows over them. No idea.

The water evaporates and provides the cooling, it's like a swamp cooler for a house in the desert.

 

[poadeleted21]

What is it? Drag

 

[Henning]

What is it? Drag

Not particularly bad though, and it works pretty well. I liked the older flap one, but I doubt it was much less drag.

 

[docmirror]

I have the Bonanza with the evap AC. The square canister at the back with the little latches on it has a set of frangible wicks that absorb water very well. There is a recessed(NACA style) scoop on the top. Pour about 1/2 gal of water in the scoop and it flows down over and saturates the wicks. Then you take off, and the air blows over the wicks and the water evaporates out at a measured rate.

In very humid weather it doesn't work well of course. In hot dry weather it's fantastic. It not only cools the interior, but it also helps with the natural reduction in humidity inside the plane at altitude. When I go to NM or CO in the summer, I fill it before take off and even on a 100F day on the ground, once I get over about 3000' it's gets rather chilly inside. Above 6000' it's quite cool. The water lasts about 2-4 hours depending on the dew point spread. Just carry a jug of distilled water, and fill it at each fuel stop.

In humid weather an actual recirculating closed AC system would work much better, but the Beech evap system is light, simple, low drag, and effective when in drier conditions.

 

[Pilawt]

I have the Bonanza with the evap AC. The square canister at the back with the little latches on it has a set of frangible wicks that absorb water very well. There is a recessed(NACA style) scoop on the top. Pour about 1/2 gal of water in the scoop and it flows down over and saturates the wicks. Then you take off, and the air blows over the wicks and the water evaporates out at a measured rate.

Yes. The description of the air conditioner from the J35 owner's manual is copied below. The photo in the OP, though, is the "New rear intake fresh air scoop for quieter and more abundant ventilation," introduced on the 1966 Model V35.

 

[Henning]

The one in my Travelair worked great out in the desert SW, problem is they don't do anything on the ground where you need AC the most.