Tag: 6632

The misty and gloomy weather today put paid to an attempt at photography in an RE8.  But it was an opportunity to rise above the murk in a height test, in which Greg took a BE2e to over 8,000 ft.

Log book entry

Date: 13.4.18 
Hour: 9.10 
Instructor: – 
Machine type and No.: RE6632 
Passenger: – 
Time: 20 min 
Height: 1500 
Course: Photos, unsuccessful owing to heavy mist.

Date: 13.4.18 
Hour: 10.15 
Instructor: – 
Machine type and No.: BE8646 
Passenger: – 
Time: 45 min 
Height: 8,200 
Course: [Aerodrome] 
Remarks: Height test.

Heavy Mist

The Met Office’s weather report for Salisbury Plain for the morning of 13 April was the laconic c . omg. Since we are in 1918 and not 2018, the meaning was not “cloudy . omigod” but “cloudy, turning to overcast, mist and gloom”.  This was certainly consistent with heavy mist rendering the attempt at aerial photography unsuccessful.

Up where it’s cooler…

But 45 minutes after landing, Greg was up in the air again to do a height test, and he reached 8,200 ft. 

So how cold was it up there?  Well, the recorded minimum and maximum temperatures for Salisbury Plain that day were 37°F and 52°F, respectively.  So let’s assume that at mid-morning in Yatesbury it was 45°F (7°C) at ground level.  

Using the temperature gradient for low altitudes[1] of

• -3.3°F/1,000 ft in cloud and 
• -5.4°F/1,000 ft in clear air,

and assuming for the sake of argument that there was

• 2,000 ft of cloud and 
• 6,200 ft of clear air

that gives a temperature at 8,200 ft of around 5°F or -15°C.

But what about wind chill?  Greg was in an open cockpit, with an indicated air speed in the BE2e probably between 50 and 70 mph, so it would have felt colder.

How much?  Assuming a speed of 55 mph and using the wind chill calculator at CSGnetwork.com[2], we obtain:

• -48°F or -44°C using the old formula and
• -25°F or -32°C using the new formula.

Not having a good basis to choose between them and therefore splitting the difference, we end up with a temperature that feels something like -37°F or -38°C

Whichever temperature scale you use, this is cold.  So the leather flying helmet, the goggles, the silk scarf, the fur gloves that make bear paws look small, the sheepskin boots, and the thick leather flying coat over the tunic all now make a lot more sense.

That’s it for a Few Days

The next entry in Greg’s pilot’s log book is for 20 April 1918.  Maybe he had some leave, in which case he probably went back home to Holyhead, or maybe he was still in Yatesbury at ground school.

À bientôt…

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[1] Taken from the mountain meteorology site https://www.onthesnow.com/news/a/15157/does-elevation-affect-temperature

[2] http://www.csgnetwork.com/windchillcalc.html