Ardmore 2022

[Charl]

Warbirds had a great Open Day last Sunday.
I know you know what this is, can't quite place it:

[deaneb]

Ryan PT-22 Recruit. A WWII US Army Air Corp trainer.

[Charl]

Ah Yes! Thanks Deane.

Good to see the Strikemaster back in camo, it spent some time as a lime green advertising hoarding...

[Charl]

Since visiting Omaka I have become more interested in the WWI birds, and was great to see them in the air.
Auckland weather played the game, no rain but it was a little gusty.
This required careful focus from the flyers, but no vintage aircraft were hurt in the process.

[Charl]

Haven't been to Ardmore for a while, and it was great to get up close with all that vintage hardware.







Some shiny newish hardware, too:

[Splitpin]

Charl....great post, beautiful shots, memory-triggering video.
I remember the "Bluntys" coming into Wigram, just like in your video, they would taxi in, and once parked...increase the RPM and shut down.
So, my question is ...why? after 40-something years.

Charl, that last photo is very well done.

[deaneb]

I remember the "Bluntys" coming into Wigram, just like in your video, they would taxi in, and once parked...increase the RPM and shut down.
So, my question is ...why? after 40-something years.

I'm pretty sure its to stabilise the engine temp before shutting down.

[Splitpin]

Cheers Mr B

[Charl]

I once asked a hotrodder why they revved the engine just before shutting it down.
He opined that it just "Sounded Cool".
Turns out: if you turn the ignition off mid-stroke at high revs, unburnt fuel enters the cylinders, washes the oil off and creates corrosion pitting.
When the smoke eventually starts coming out as a result of this, you re-bore the motor and put in oversize rings.
Apparently it then goes faster

[deaneb]

I once asked a hotrodder why they revved the engine just before shutting it down.
He opined that it just "Sounded Cool".
Turns out: if you turn the ignition off mid-stroke at high revs, unburnt fuel enters the cylinders, washes the oil off and creates corrosion pitting.
When the smoke eventually starts coming out as a result of this, you re-bore the motor and put in oversize rings.
Apparently it then goes faster

Indeed this is the reason that piston aircraft are shut down by cutting the fuel, not turning off the magnetos (ignition). It prevents oil washing.

On a gas turbine engine there are no cylinders to wash, but cutting fuel is the only option as they are are a constant combustion cycle and there is no ignition source (other than the self sustained heat of combustion) after they are started.

[Charl]

they would taxi in, and once parked...increase the RPM and shut down.
So, my question is ...why? after 40-something years.

I went looking further but found this:

When an engine has been operated at high power levels for extended periods of time, a cool down time should be allowed before shut down. It is recommended the engine be operated at below a low power setting, preferably at idle for a period of 5 minutes to prevent possible seizure of the rotors. This applies, in particular, to prolonged operation at high rpm on the ground, such as during engine trimming. The turbine case and the turbine wheels operate at approximately the same temperature when the engine is running. However, the turbine wheels are relatively massive, compared with the case, and are not cooled so readily. The turbine case is exposed to cooling air from both inside and outside the engine. Consequently, the case and the wheels lose their residual heat at different rates after the engine has been shut down. The case, cooling faster, tends to shrink upon the wheels, that are still rotating. Under extreme conditions, the turbine blades may squeal or seize; thus a cooling period is required if the engine has been operating at prolonged high speed.

cutting fuel is the only option as they are are a constant combustion cycle and there is no ignition source (other than the self sustained heat of combustion) after they are started.

OK, so why would the Blunty want to rev it before cutting the fuel?

[K5054NZ]

Lovely photos Charl, thanks for sharing!

For those interested: both the P-40 and P-51D are for sale.

Good to see the Strikemaster back in camo, it spent some time as a lime green advertising hoarding...

Different Blunty - that was NZ6370/ZK-STR.