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  1. #1
    150+ Forum Groupie Roland's Avatar
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    Question on ventilation in small aircraft

    I'm working on adding some ventilation effects in my single seater cockpit. Basically two electric fans blowing your face and body that are speed controlled via software. Currently I can mix engine RPM and airspeed to control the fans. Some first results are described at http://www.simprojects.nl/wind_in_your_face.htm
    Maybe I'm way off in my assumptions, so I would appreciate if someone could give me some info on how the actual ventilation in Cessna type of aircraft works and feels during engine start, take-off and flight. As far as I know, the ventilation intake is on the left and right top sides, at the wing front. I don't know how the engine RPM affects this air intake, and whether there are other areas in the cockpit that give you hints of engine and airspeed related ventilation effects.

    Thanks!
    RR

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    1000+ Poster - Fantastic Contributor Jackpilot's Avatar
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    From these two outlets that you describe:
    Zero air is coming in until the aircraft moves fast(means fly)
    After that there is basically no speed related variation in the airflow. They work on a ram effect basis and pump in as much air as their diameter allows.
    You are better off with wind sound to replicate the "ambiance" and have your blowers work at full capacity when you get airborne.
    Jackpilot
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    2000+ Poster - Never Leaves the Sim Michael Carter's Avatar
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    In addition to what JP mentioned, the air enters an opening in the leading edge of the wing and is routed to two adjustable (if not broken) vents located near the windscreen in the wing root.

    They move in and out and turn forward and af to direct the airflow.
    Boeing Skunk Works
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    Boeing 777 Builder


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    Quote Originally Posted by Boeing Skunk Works View Post
    In addition to what JP mentioned, the air enters an opening in the leading edge of the wing and is routed to two adjustable (if not broken) vents located near the windscreen in the wing root.

    They move in and out and turn forward and af to direct the airflow.
    Mikes right, in most Cessna's I've flown these air vents have indeed been broken. Never the less they only let in air once the aircraft is moving fairly fast and therefore airborne and can be adjusted in a rudimentary fashion by pulling them in and out. I agree that your best effect would be via sound not so much air flow. Just have the fans turn on at lift off and blow full speed.

    Ken.
    Opencockpits | Aerosim Solutions | Sim-Avionics | P3D | FDS | FTX | AS16 | PPL | Kennair


  5. #5
    150+ Forum Groupie Roland's Avatar
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    Thanks for the info.

    So my assumptions for the Cessna were way off. I would have expected that the propellor at least would contribute a bit, but I guess the inlet is above the prop-wash flow.
    The fan control is flexible, so I could program the behavior for the Cessna as you mentioned.

    Never too old to learn!
    RR

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    Quote Originally Posted by Roland View Post
    I'm working on adding some ventilation effects in my single seater cockpit. Basically two electric fans blowing your face and body that are speed controlled via software. Currently I can mix engine RPM and airspeed to control the fans. Some first results are described at http://www.simprojects.nl/wind_in_your_face.htm
    Maybe I'm way off in my assumptions, so I would appreciate if someone could give me some info on how the actual ventilation in Cessna type of aircraft works and feels during engine start, take-off and flight. As far as I know, the ventilation intake is on the left and right top sides, at the wing front. I don't know how the engine RPM affects this air intake, and whether there are other areas in the cockpit that give you hints of engine and airspeed related ventilation effects.

    Thanks!
    Hi Roland

    Additionally the smaller Cessna Aircraft have a flap on the starboard engine cowling which is opened via a cable and handle in the cockpit which can be opened and closed as required. This directs air through into the cabin beneath the front windows to help with cooling and demisting.

    There is actually a small amount of cooling from this when the aircraft is stationary as the flap on the cowling is more inline with the airflow from the propeller.

    Also you should bear in mind that the air is cooler as the aircraft climbs by about 2 degrees for every thousand feet which makes a noticeable difference with the temperature in the aircraft in flight.

    Regards


    Lufty

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    I wouldn't worry too much about the wind ... if you step into a small plane if it is hot outside, it is very hot inside and if it's cold it is the same.
    It is only once you are flying that it becomes comfortable, unless you have the latest versions with airco !
    [

  8. #8
    150+ Forum Groupie Roland's Avatar
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    Quote Originally Posted by LUFTY View Post
    Also you should bear in mind that the air is cooler as the aircraft climbs by about 2 degrees for every thousand feet which makes a noticeable difference with the temperature in the aircraft in flight.
    You're right, a glider pilots also mentioned this, saying it really could get cold in the cockpit. I tried to add this cooling effect with Peltier elements, but I found out they are not powerful enough. Adding a small airco for cooling the incoming air with altitude increase could be done. I'll check around. Thanks!
    RR

  9. #9
    1000+ Poster - Fantastic Contributor Jackpilot's Avatar
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    Just my two cents...replicating the annoyances of a small unpressurized and poorly heated/ventilated airplane is going very far into immersion!!
    I live in Canada, flying in winter means that the cockpit temperature can be minus 15degree C during the preflight checklist. (colder is unsafe for flying a single engine)
    In Summer, on the ramp, it can be plus 40 degree C. Hard to replicate!
    Just a matter of getting dressed accordingly...in my humble opinion it has nothing to do with the pleasure of flying, outside tempature is more of a factor affecting engine and airframe performance and settings ...the physical feeling goes more or less unnoticed against the excitement of a flight.
    The Sim airliner cockpit is much easier on that subject..it tends to become very hot (computers) and real ducted fans bringing in fresh air from somewhere else greatly contribute to the realism of comfortable altitude flying.
    Jackpilot
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  10. #10
    10+ Posting Member venenoso's Avatar
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    Quote Originally Posted by Boeing Skunk Works View Post
    In addition to what JP mentioned, the air enters an opening in the leading edge of the wing and is routed to two adjustable (if not broken) vents located near the windscreen in the wing root.

    They move in and out and turn forward and af to direct the airflow.
    more info , here is a link of this cessna wing leading edge http://www.aircraftspruce.com/catalo...es/ventube.php
    regards,

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