Touch and Go's = loss of air pressure (no brakes)? - Page 2 - ED Forums
 


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Old 02-10-2019, 09:13 PM   #11
MiG21bisFishbedL
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Quote:
Originally Posted by 9./JG26_Brigg View Post
So it's necessary to get the landing gear back to neutral as quickly as possible to save pressure. Did not know that, thx fella as I just used to do it when I remembered
If you're going off of real world flight experience with retractable gear in GA, don't. In jets, the moment you establish a positive rate of climb, retract that gear. So, in practice, you basically pull up the gear within moments of reaching rotational speed.

Don't be waiting until you've run out of usable runway, just pull up those wheels as soon as you're climbing out.
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Old 02-10-2019, 10:24 PM   #12
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Originally Posted by Quadg View Post
brakes, landing gear and chute all use pressure.

Do you have anything to back this up? My Mig-21 manual states raising and lowering gear use the main hydraulic system.


The pneumatic system is for brakes, jettisoning the RATO units, drag chute and doors, sealing canopy, and control over anti-icing, liquid cooling systems and pressurizing the radar.


Note that wheel brakes are applied when the gear handle is in the up position. Perhaps you bled all your air from repeated gear up during practice?
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Old 02-11-2019, 04:10 AM   #13
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Note that wheel brakes are applied when the gear handle is in the up position. Perhaps you bled all your air from repeated gear up during practice?
That's what I'm thinking. If I only do three circuits I'm fine. If I do five or six I run out of air.

Now the thing that confuses me is, why does the air get depleted when brakes are applied with gear up, but air does not get depleted when using brakes during taxi?
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Old 02-11-2019, 05:41 AM   #14
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Air is depleted during taxi. Check your gauge to the right of the stick. One reason for the nose gear break, to save air.

Refueling on the ground should replenish your air if your low just like radar coolant
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Old 02-11-2019, 05:45 AM   #15
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I recently got in the habit of checking the gauge prior to takeoff and prior to landing. The needles are always at the 12 and 6 o'clock positions.
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Old 02-11-2019, 08:58 AM   #16
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It’s the gauge on the right closest to to you, turn on English cockpit of that’s better than cryllic for you. During taxi you will see it depletes as you use your brakes. Taxi slow for minimal brakes in turns, taxi fast enough in straight lines to use rudder. It depletes fast which might be why you only see full or completely empty. Whatch it closely during taxi during every time you hit breaks

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Old 02-11-2019, 09:17 AM   #17
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Originally Posted by Nealius View Post
Now the thing that confuses me is, why does the air get depleted when brakes are applied with gear up, but air does not get depleted when using brakes during taxi?
Its just about quantity. You taxi at no more than 20-30 km/h I presume, and make small corrections with the brake. When gear up the system has to immediately stop the wheels from 300-350 km/h. As for touch and go's they are permitted but only using the full circuit to give the brakes time to cool. Still we need a technical manual verification on compressed air use and expense. Maybe its ok, maybe not quite.
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Old 02-11-2019, 09:37 AM   #18
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Originally Posted by AeriaGloria View Post
It’s the gauge on the right closest to to you, turn on English cockpit of that’s better than cryllic for you. During taxi you will see it depletes as you use your brakes. Taxi slow for minimal brakes in turns, taxi fast enough in straight lines to use rudder. It depletes fast which might be why you only see full or completely empty. Whatch it closely during taxi during every time you hit breaks
The brake pressure gauge, or the main/aux pressure gauge?
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Old 02-11-2019, 11:46 AM   #19
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It really shouldn't be a problem, you can use the brakes all you want on taxi and do a touch and go whilst still having ample air to brake and deploy the chute on the second attempt.
More landing attempts than that and you came in with too much fuel anyway.
For practicing pattern work keep your gear down if you simply must do so many consecutive passes.
Also the emergency brake uses a back up air supply in case you are caught short
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