Classic British Flight Sim

Can anyone point me in the right direction of a tutorial of how to use the Cabin pressurisation system on Dave Maltbys BAC1-11.

I have tried allsorts to get it right but always get the cabin pressure warning about FL110.

Hope someone can help...

Thanks

Very simple Indigoed

On the pressurization panel there are two switches make sure the right one is down and no horn


And welcome to the forum


Leif

Hi Indigoed
Also check that if you are using the ED version,I think the switch to which Leif refers is on the OH panel and operates in the opposite direction(like several other switches on the ED version).ATB EricT

Hi Indigoed

When I fly the 1-11 I set the cabin pressure to 4000ft and get no Cabin pressurisation warnings.

Hope this helps as well.

Regards Nigel.

Yep, that about covers it.
Basic operation is just to click the 'Safety Valve' switch to Closed. If you're a really advanced user you can select a required cabin altitude.

The Safety valve switch & pressure differential indicator are indeed on the overhead on the 1-11 510ED. The regular 1-11 has it all on the centre section of the main panel.
http://www.dmflightsim.co.uk/html/1-11/ ... CENTRE.htm

For any that may not fully understand what the pressurization system is doing, here's the basics... (Forgive any inaccuracy, I'm not an expert :think: )
When flying pressurized, you hold a higher air pressure inside, just as if you were actually flying at a lower altitude & that is known as your cabin altitude.
When flying unpressurized, cabin altitude simply changes with the aircraft's altitude.
The most comfortable conditions would be to keep cabin altitude near zero (sea level). But holding all that air inside would mean the pressure difference (between inside and out) rises to dangerous levels when flying at high altitudes.
So as you go higher, you let some air out (increase cabin altitude) & that keeps the pressure differential safe.

You get these gauges to play with...

Cabin Alt to Baro Pressure. Click the 'A' knob to select your required cabin altitude. Set required alt back to zero when you start descent.

Cabin Altitude indicator. Anything over 10000 ft gives a warning light and sounds the horn.

Pressure Differential indicator. Max level of 7.5 psi is marked in red.
Max psi is 0.5 psi if the outside pressure is greater than inside (negative pressure differential). The 1-11 allows you to start raising the cabin alt before takeoff.

Cabin Rate of Climb indicator shows how fast the cabin altitude is changing.
Normal max rate is about +/- 400 ft/min. 'R' knob on the Cabin Alt to Baro Pressure gauge alters the rate.

Safety Valve
Needs to be closed (air tight) for pressurized flight. Even though closed, it's calibrated to be forced open if the pressure goes beyond max limits.
After a pressurized flight, the Safety Valve is opened so that any pressure difference is settled before the doors are opened.

Hope that helps.
DM

Sorry David

I figured give him the simplest fix then RTFM

BTW I don't fly 500s so Its always on the bottom Right for me


Leif

Hi Dave,

Yes I agree with your basic summary but would add that the engines are being bled to supply an airflow into the aircraft and it has to go out again continuously...So the Pressurisation Control Valves work away to adjust how much they are open to let the air out. These valves would only close in the event of a failure to supply engine bleed air. If the supply fails then they would shut immediately and the cabin altitude would be stabilised but climbing slowly due to leaks...While the crew would be busy descending because of the failure.

Think of it this way...In stabilised pressurised flight at altitude the engines supply an air supply IN...This air must be let OUT at the same rate as it is coming in or the aeroplane would inflate like a balloon and burst. It is the job of the Pressurisation Control Valves to control that out flow rate to maintain the cabin pressure at a certain value dependant on the Altitude of the aircraft. The inflow from the engines will vary as the power settings of the engines are changed by the crew and as speed and altitude change. So the PCVs can be quite busy sensing and adjusting...One engine suddenly fails!...Immediately the PCVs respond to the lesser flow in by closing a bit to lessen the flow out.

Just as a matter of interest a window blowing out of Concorde at near 60,000 feet could be coped with...The PCVs would just adjust to reduce their outlet by the same amount as the lost window is letting out. That is why the windows on Concorde were so small...Bear in mind that ones useful conciousness at 60,000 feet breathing 100% oxygen is about ten seconds. This is because even with 100% oxygen, at that altitude the partial pressure of that oxygen is insufficient to make it pass into the blood. The only way for man to survive at 60,000 feet is to a) be pressurised or b) be pressure breathing.

a) is easy and we do it everytime we fly in an airliner...b) is extremely difficult and you need to practice it for about a week before you are competent. I have done b) and I promise you it is very hard to do.

It is important to remember that using a spacesuit is not b), it is a) because your spacesuit is fully pressurised like a little aeroplane fuselage so you are just breathing normally in there...Whoops, sorry for the lecture...Got carried away there :redface:

Thanks for that Peter.
No, 'air tight' and 'holding air' is not the right sort of idea is it. It's pressure controlled.
More like one of those bouncy castle inflatables. It's got a flow of air that constantly feeds the pressure. Stop the flow and the air gently escapes.

DM

Thanks Peter
Leif was just the other night giving me details on the 748 systems
as we were working on a real virtual situation in the VA
It's a real privliage to learn from you gents
Btw
you can get carried way all you want......
just don't go anywhere :tuttut:

Thanks for all the tips -

I promise I did RTFM but couldnt find anything about the pressurisation system.

Maybe I was looking in the wrong bit of the manual.

Thanks again all

Nice to be here