bilbeisi9
Topic Author
Posts: 4
Joined: Thu Apr 06, 2017 9:27 pm

Help with non-pressurized aircraft ECS

Thu Apr 06, 2017 9:48 pm

Hello,

Im an engineering student working on designing a non-pressurized search and rescue aircraft. I have been assigned to work on the aircraft's environmental control system (ECS), specifically the temperature control of the cabin, and am having trouble getting a grasp on what features of the aircraft's air conditioning machine would not be included since it is not a pressurized vessel. I have been reading quite a lot on air-cycle machines and inverse-brayton cycles and am wondering as to how the engine bleed air for this non-pressurized aircraft is cooled and delivered to the cabin. I hate to say this but I am kind of in a hurry if anyone can help me this is quite urgent. Thank you in advance to anyone who can help me out.
 
Woodreau
Posts: 1320
Joined: Mon Sep 24, 2001 6:44 am

Re: Help with non-pressurized aircraft ECS

Thu Apr 06, 2017 10:25 pm

I'd wager it's probably not much different. Just no outflow valve. The whole cabin is a big outflow valve.


Just like one of those air conditioned Cessna 172s that can only hold two passengers and fuel.
Bonus animus sit, ab experientia. Quod salvatum fuerit de malis usu venit judicium.
 
bilbeisi9
Topic Author
Posts: 4
Joined: Thu Apr 06, 2017 9:27 pm

Re: Help with non-pressurized aircraft ECS

Thu Apr 06, 2017 10:42 pm

Hello Woodreau, thank you for your reply, I appreciate it very much. So if I understand you correctly, first of all their definitely IS an air cycle machine in non-pressurized aircraft and it would consist of the usual 2 heat exchangers, a turbine, and a compressor. And the bleed air is cooled in a heat exchanger with RAM air. Just for the record we are only looking to heat the cabin at our cruising altitude of 13,000 ft.
 
User avatar
Web500sjc
Posts: 662
Joined: Tue Sep 15, 2009 4:23 am

Re: Help with non-pressurized aircraft ECS

Fri Apr 07, 2017 1:51 am

Look at a Cessna 172 or Air conditioned GA aircraft for the EVS for a non pressurized aircraft. No need to reinvent the wheel.
Boiler Up!
 
7673mech
Posts: 277
Joined: Tue Mar 30, 2004 10:10 am

Re: Help with non-pressurized aircraft ECS

Fri Apr 07, 2017 5:34 pm

If it is a piston aircraft? why use bleed air?
Ram air heated by the motor should be fine.
 
737tanker
Posts: 288
Joined: Fri Dec 30, 2005 2:47 am

Re: Help with non-pressurized aircraft ECS

Sat Apr 08, 2017 11:57 am

For heating and cooling a non-pressurized turbine aircraft look at the Beech 99 and the Dornier 228
 
Dalmd88
Posts: 2529
Joined: Fri Jul 28, 2000 3:19 am

Re: Help with non-pressurized aircraft ECS

Sat Apr 08, 2017 1:23 pm

The real differences between pressurized and non is the airframe and the size of the ECS system. In a non pressurized aircraft the fuselage is not robust enough for the pressure cycles and there is no pressurization controller to control the outflow valve. You would still have a overpressure dump valve and the ECS would be downsized to only provide conditioned air and not the volume you would need not pressurize the vessel.

Thinking back thirty years to my Be99 days, I recall there was a electric heater and a VCS air conditioning system that were mostly used on the ground. Yes, it was basically an automotive system mounted on one of the engines. It was a real pain to keep working. Beech had tons of problems with compressor mounts and the seals on the entire system were always going bad on our old Be99.
 
bilbeisi9
Topic Author
Posts: 4
Joined: Thu Apr 06, 2017 9:27 pm

Re: Help with non-pressurized aircraft ECS

Thu Apr 13, 2017 7:19 pm

Hello all, I thank you very much for your replies. I have made a decision as to the design implementation of our aircraft, feedback is more than welcome. I have decided to go with the final design of heating RAM air by the motor and pumping it into the cabin. Avionics will be cooled by free stream air flowing through a vent. Does this make sense and is this applicable? I am also aware of heating the cabin by having a combustion heater, but decided it was a more complex and power consuming design.
 
dragon6172
Posts: 816
Joined: Sat Jul 14, 2007 9:56 am

Re: Help with non-pressurized aircraft ECS

Thu Apr 13, 2017 9:41 pm

Are you actually going to be rescuing folks with the aircraft? Or just search? If you are actually picking folks up in a rescue situation then being able to control the cabin temperature is a bit more important to help with hypothermia. You may want to go with a more complex/reliable system. If you are just heating the cabin for crew comfort during a search operation, then it can be secondary.
I work on EMS helicopters, and if our heater or air conditioner is broken we are essentially out of service since they are not allowed to carry patients. It can be MEL'd, but in reality does no good for operation reasons.
Phrogs Phorever
 
bilbeisi9
Topic Author
Posts: 4
Joined: Thu Apr 06, 2017 9:27 pm

Re: Help with non-pressurized aircraft ECS

Thu Apr 13, 2017 9:49 pm

Hello dragon, I appreciate your response. The aircraft our team is designing is a fixed-wing search and rescue aircraft. To my knowledge the aircraft will only conduct the searches and in return dispatching the choppers to do the rescuing. Please stop me if my information is incorrect.

Who is online

Users browsing this forum: vijeetmehta and 2 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos