So this was it. The last day of training in a (relatively) safe environment, with no-one wishing you harm, and no one shooting at you from the ground or the air.
The last day at Hursley Park/Worthy Down was evidently something of a recap, with a shoot (complete with ground strips) and zone calls being rehearsed. Not a bad thing, either.
Last log book entry during training
Date: 27.5.18
Hour: –
Machine type and No.: RE 6650
Passenger: –
Time: 1 hr 15 m
Height: 3000
Course: Shoot. Gr. Str. & Zonecalls
Remarks: Successful
But this time the flight was longer, with the sortie lasting more like the 2-3 hours that would be typical for a shoot in Greg’s squadron on the Western Front. Greg would have been flying in figure-of-eight patterns, as suggested in the SS 131 booklet “Co-operation of Aircraft with Artillery”, Revised Edition, as issued by the General Staff in December 1917:
Figure-of-eight circuits flown when observing a shoot. The points ‘G’ are when the aircraft signals ‘Fire’. The battery’s ground aerial is laid parallel to the ‘corrections’ leg.
And as a coda, there was some reconnaissance to end the day.
Popham panels were first mentioned in a post for 5 April 1918. They were the possible subject of a hard-to-read log book entry while Greg was at Yatesbury:
To recap, Popham panels, or T-signalling panels, were a means of ground-to-air communication. They were introduced towards the end of the war. Their use was principally by the infantry, as an alternative to the 12′ x 1′ “ground strips” used by the artillery to make up letters and symbols. I would guess that the ground strips were more favoured by airmen as they were larger and easier to see. But the smaller size of Popham panels would have made them much more practical for infantry use.
Instruction in Popham panel reading was certainly undertaken at Hursley Park. Dave Key’s post for 11 May 2018 on The History of Hursley Park website shows a course paper (the third image of the post) that refers to the following.
2. Lecture Popham panel & its use. Procedure of mess-
ages Battn. & Bde. H.Q. & message dropping.
Message pads & tracings-Flares - Final
Report & Interview
Greg may have attended a lecture like this, perhaps on a non-flying day like today.
And when it came to the…
6. Practical. Popham Panel Reading
…then this is how it would have looked from the ground:
Greg’s pilot’s log book doesn’t contain any indication of Popham panel practical work at Hursley Park/Worthy Down. Maybe he just didn’t record it, or perhaps he was already specialised in the ‘ground-strips-and-artillery’ stream.
In an important training exercise, Greg begins today to practice ‘zone calls’.
Log book entry
Date: 29.4.18
Hour: 2.35
Machine type and No.: DH 5155
Passenger: –
Time: 55 m
Height: 3000
Course: Aerodrome
Remarks: Practice.
Date: 29.4.18
Hour: 5.55
Machine type and No.: DH 5155
Passenger: –
Time: 1 h 20 m
Height: 3000
Course: –
Remarks: Zone calls
Date: 29.4.18
Hour: 8.0
Machine type and No.: RE 5146
Passenger: –
Time: 30 m
Height: 2500
Course: Aerodrome
Remarks: Practice 1 landing.
Zone Calls
Zone calls are one way wireless messages by Morse code from aircraft to artillery batteries giving information about targets, such as enemy batteries firing, enemy transport and troop movements.
A zone call might be something like:
NF L 26 c 2 0
Example of a zone call, with map reference – somewhere in France. All will be revealed on 8 August (although there is enough information in this post to identify where…). Adapted from 1:10,000 scale trench map (credit: Great War Digital).
This would mean: Guns Now Firing from a position at map reference L 26 c 2 0. Maps of the Western Front (and presumably maps used by Greg’s Training Squadron at Yatesbury) used a reference system that was a combination of squares and a grid.
Each 1:40,000 map sheet was divided into twenty-four 6,000 yd squares, arranged in a 6 x 4 array and lettered A to X – in our case, L.
Each 6,000 yd square was in turn subdivided into thirty-six 1,000 yd squares, numbered 1 to 36 – in our case, 26.
Each 1,000 yd square was then subdivided into four quadrants (a, b, c, d) – in our case, c.
Finally, a decimal grid reference (eastings and then northings) was used to specify the intended position with the required degree of precision. This could be to one significant figure as in our example (2 0), which identified a 50 yd square. Or it could be to two significant figures if greater precision was desired and achievable (22 01, for example), which would identify a 5 yd square within the 50 yd square denoted by 2 0.
Fine levels of detail are not visualisable on a 1:40,000 map. The artillery and infantry tended to use 1:20,000 and 1:10,000 scale maps, depending on the purpose in hand, which were revised periodically as trenches and other ground features changed. These revisions, incidentally, would rely heavily on the aerial photography of work of the corps squadrons. The complete map reference would include the number of the 1:40,000 sheet (eg Sheet 36A, to give 36A L 26 c 2 0), but the sheet number was typically understood in context and therefore omitted in zone calls.
If this combination of squares and grid references sounds complicated, it is not actually different in principle from an Ordnance Survey grid reference, which in one of its incarnations uses a combination of an identified square and a decimal grid reference within the square. For example, the OS reference SU 053711 is based on a 100 km square designated SU and then, within that square, a three significant figure decimal grid reference 053 711. This in turn identifies a 100 m square – which, as it happens, is on the former Yatesbury airfield (1:50,000 Landranger sheet 173 in today’s OS maps).
A zone call was a one way wireless message from the aircraft to an artillery battery on the ground. Ground to air communication was done by ‘ground strips’, as explained in this earlier post:
Another day of work in both an RE8 (dual control, with Lt Thomas) and a DH.6 (solo). Plenty of landings in the RE8, and a somewhat hard to decipher log book entry for the DH.6:
Log book entry
Date: 5.4.18
Hour: 6.45
Instructor: Lt Thomas
Machine type and No.: RE3551
Passenger: Self
Time: 45 min
Height: 1500
Course: Aerodrome
Remarks: Landings (9). Dual.
Date: 5.4.18
Hour: 3.25
Instructor: –
Machine type and No.: DH2130
Passenger: –
Time: 1 hr 20 min
Height: 2000
Course: [Aerodrome]
Remarks: Ground stps & Pann: Successful
So, what is “Ground stps & Pann” all about – if that is indeed what it says?
Log book entry (enlarged)
My best guess is that it is referring to artillery cooperation work and, specifically, to the use of ground strips and panels.
Although by 1918 the reconnaissance aircraft of the RFC and RAF were equipped with radios, and although those radios were by then small enough so that they did not take the place of the observer – who by this stage was principally responsible for the defence of the aircraft in flight – there was still a problem. That was that radio communication was one way only: from air to ground. Signals from the aircraft were received by RFC/RAF wireless operators attached to artillery units, which in Greg’s case were typically Royal Garrison Artillery Siege Batteries.
Ground Strips
So how did the ground wireless operator communicate back to the aircraft? Various methods were tried during the course of the war. Signalling lamps were not an enduring success, not least because of the need for the pilot to be actually looking in the direction of the lamp at the moment of signalling, which was not always feasible. A better solution proved to be the more primitive sounding strips of cloth laid our on the ground: ground strips. These were typically 12 ft x 1 ft (3.7 m x 0.3 m) strips of white cloth, which could be arranged into pre-designated code symbols or letters. Here are some examples, taken from The Illustrated London News of 23 January 1915 p107, which were stated to be “merely typical signals, and do not represent any actually in use” – just in case it should fall into the wrong hands:
“CODE OF LETTERS used for signalling from ground to the airman above”. Image credit: British Newspaper Archive (www.britishnewspaperarchive.co.uk), The British Library Board and Illustrated London News Group.
¦ Direction of Target
L Observe for line
X Observe for range
Z Observe for fuze
V Observe for effect of fire
N Repeat last signal
T Land
F Fresh target (additional letters are used with this signal)
And if there was snow on the ground, then dark coloured strips were used instead.
So much for “Ground stps”. What about “& Pann”?
Panels
I have hazarded above that “Pann” refers to panels. An apparent difficulty with this theory is the rather imperfect abbreviation: too many ‘n’s. But although current dictionaries spell the word with one ‘n’, the Oxford English Dictionary (completed in 1933) lists “pannel” as a variant of “panel”, as does the 1913 edition of Webster’s Dictionary. So that objection does not seem to be fatal. Furthermore, the meaning is a good contextual fit.
The Popham or T-signalling panel was an alternative means of ground-to-air communication introduced towards the end of the war, in use by the infantry in particular. In the official pamphlet SS135 “The Division in Attack” (available for download here) issued by the General Staff in November 1918 it is described as consisting of:
…a black or dark blue cloth to which are sewn strips of white Americal cloth in the shape of the letter “T”.
From this “T” project nine arms of white American cloth. These arms are provided with flaps of black or dark blue cloth, so that any or all of them can be covered or exposed to view from the air at will.
These arms are numbered consecutively from 1 to 9, as shown in the following diagram, and are always known by these numbers:
Popham T Panel
Then by covering and exposing appropriate arms, a large number of combinations of numerals may be set out, of which the following are three examples:-
Popham T Panel examples
… A simple figure code is used with the panel, each group of numerals representing a phase or sentence which the infantry are likely to wish to send to the aeroplane.
It niggles me that this was principally an infantry means of communication, rather than artillery, and Greg’s future role was in artillery cooperation. But maybe his speciality hadn’t yet been decided upon. And the question remains: if “Pann” doesn’t refer to Popham T panels, what does it mean?
