Monthly Archives: April 2016

Paint from the Past

Entire sample - smThis old fabric sample is slowly revealing its secrets.

Using a digital microscope, I was able to closely example the cracked paint surface and actually see the different layers of paint and dope that have been applied over the years.  It’s surprisingly complex.

Most of the sample as you see it here was not painted at all.  The brown-colored areas are only coated with three semi-transparent layers.  The bottom layer, clearly a transparent dope of some sort, is slightly yellowish.  The next transparent layer looks like glass and is a sort of green/yellow color.  On top, which is giving it most of its color, is a brown layer that is still semi-transparent.  I don’t know which of these are true “dope” or which may be some sort of a clear coat.  It’s also possible that one or more of these layers may once have had some sort of unstable pigment in them, which has since disappeared.  I will have to do some real chemical analysis I think if I want to dig any deeper into their composition.


Dope - yellow dope - brown dopeDope - yellow dope - brown dope 2

Along the edge of the sample is a dark stripe, some parts look dark brown/black and others are blue.  I call it the blue stripe, just for ease of reference.  It has two more layers than the main section of the fabric, and these layers are opaque paints.

Sky blue paint - yellow dope - forest green paint - brown dope Sky blue paint - yellow dope - forest green paint - brown dope 2

The lower layer of paint, sandwiched between the bottom-most layer of dope and the glass-like green/yellow layer is sky blue in color.  It may not have been well mixed as I’ve seen some spots that appear white as well, but so small that they must have been irregularities in the paint rather than intentional marks.

The other pigmented layer is a forest green.  It lies between the glass-like green/yellow layer and the top-most brown layer.  Where the brown sits over the green it makes a color that looks like coal or graphite.

Sky blue paint - yellow dope - brown dope 2 Sky blue paint - yellow dope - brown dope

The final irregularity is that I have found some areas where the green paint is absent, although the blue is still there.  I need to map these out at some point in order to determine if it seems to be an intentional pattern or just sloppily-applied paint.

If anyone knows of a way I could tell the age or origin of these paints, or better differentiate between paint and dope, please do let me know.

Transcribing RAAF History Card

I’ve just finished transcribing the E/E.88 Aircraft History Card for A17-370.  It’s all hand-written and the quality of the scan I have is very poor, but it allowed me to put together a concise timeline of where it was throughout the war.

Starting from the top.

A17-370 was built by de Havilland Aircraft Pty Ltd.  It was delivered to No. 2 Aircraft Depot on 5/24/1941 with Engine Number 193, at RAAF Base Richmond, N.S.W.  A month later it was sent to Canberra for storage.  It was finally assigned to No. 1 Elementary Flying Training School on 9/6/1941 located at Parafield Aerodrome near Adelaide, South Australia.

It was received in early September of 1941 and flew off its first 240 hour maintenance period in about three months.  Now unfortunately the meanings of many of the abbreviations and status codes use on this document have been lost, but if I’m reading this right it accumulated about 2400 flying hours total with No. 1 E.F.T.S.

By the end of its second maintenance period they noted that the engine was U/S, which means unserviceable.  However, I’m a bit puzzled because it kept being put back on the flight line.  They made that note three times over a year of flying.  I don’t know if they were replacing or servicing the engine each time, or what.  The duration of each maintenance period was always exactly 7 days, like clockwork.

As soon as they fixed the engine problem (presumably by installing the engine currently in the airplane, a British-built Gipsy Major from 1939), the wings were damaged and then repaired.  This brings us to the end of 1942.

In mid-1943 it was shipped to Victorian & Interstate Airways, a civilian contractor, for a complete overhaul.  By my math this was about 1800 hours, give or take… very close to the 2000 hour mark.  At V.I.A. it was completely rebuilt, re-covered and test flown.  This process took 49 days at Essendon, near Melbourne.  After all that work, A17-370 should have had another smooth 2000 hours ahead, more than enough to finish out the war.  But it wasn’t to be.

On February 28, 1944, a visiting Tiger Moth (A17-695) taxiied nose-first into A17-370.  The damage was noted in its history card but most of the handwriting is impossible to read.  I know that the interplane struts are mentioned, but that’s about it.  It was recommended to be repaired at Parafield by the line mechanics of 1 E.F.T.S., rather than sending it off to a depot.  I suspect this is when a lot of the damage to the cowling was done, and why it was roughly welded back together.  They worked fast, and she was back in the air only a week after the incident.

At this point No. 1 E.F.T.S. was relocated to Tamworth, N.S.W. and was gradually being phased out.  A17-370 only accumulated about 500 hours since her major overhaul at V.I.A. before the war ended for her.  On September 15, 1944, No. 1 E.F.T.S. was shut down, and by December it had been gutted and the aircraft remained behind in the care of a Care and Maintenance Unit at Tamworth.

A17-370 was stored until June 7, 1946 (less cylinder heads, apparently) when she was offered for sale.  She was sold to the Associated Aero Clubs of Australia for £100 among a whole batch of other Tiger Moths.  Unlike most of those, however, she was never civil-registered in Australia, instead remaining in storage until being shipped to India in 1949.

So that’s the narrative version, here’s the direct transcription, along with my own translations of each line and the location where it would have been at that point.

Type: Tiger Moth
No. A17-370
Engine Fitted: Gipsy Major No. 193
Order No. 74221
Received from: de Havilland Aircraft P/L
Date Received: 24.5.41
Date Details Authority Translation Location
5/24/1941 Rec 2 AD ex DH with (193) 2Q218 24/5 Received at No. 2 Aircraft Depot from de Havilland with engine number 193 RAAF Base Richmond, N.S.W.
6/25/1941 Trans Canberra for storage 2Q708 25/6 Sent to Canberra for storage Canberra, N.S.W.
8/23/1941 F at Canberra CQ508 23/8 Inspection at Canberra Canberra
9/6/1941 Allotted 1 E.F.T.S. ex Canberra 4Q131 6/9 Assigned to No. 1 Elementary Flying Training School Canberra
9/8/1941 Issued 1 E.F.T.S. ex Canberra CQ599 8/9 Shipped to No. 1 Elementary Flying Training School Parafield Aerodrome, near Adelaide, S.A.
12/6/1941 E at 1 E.F.T.S. 1Q397 6/12 240-hour maintenance Parafield
12/13/1941 C at 1 E.F.T.S. 1Q414 13/12 Parafield
2/16/1942 E Star at 1 E.F.T.S. (with similarly U/S eng) 1Q126 16/2 240-hour maintenance (unservicable engine) Parafield
2/23/1942 C at 1 E.F.T.S. 1Q153 23/2 Parafield
3/23/1942 E at 1 E.F.T.S. (with similarly U/S eng) 1Q379 23/3 240-hour maintenance (unservicable engine) Parafield
3/30/1942 C at 1 E.F.T.S. 1Q422 30/3 Parafield
4/13/1942 E at 1 E.F.T.S. 1Q494 13/4 240-hour maintenance Parafield
4/20/1942 C at 1 E.F.T.S. 1Q512 20/4 Parafield
6/1/1942 E Star at 1 E.F.T.S. (with similarly U/S engine) 1Q65 1/6 240-hour maintenance (unservicable engine) Parafield
6/8/1942 C at 1 E.F.T.S. 1Q690 8/6 Parafield
12/14/1942 E at 1 E.F.T.S. (M/P’s dam.) 1Q335 14/12 240-hour maintenance (wings damaged) Parafield
12/21/1942 C at 1 E.F.T.S. 1Q353 21/12 Parafield
1/18/1943 E at 1 E.F.T.S. (240 hourly) 1Q39 18/1 240-hour maintenance Parafield
2/1/1943 C at 1 E.F.T.S. 1Q59 1/2 Parafield
4/12/1943 E Star at 1 E.F.T.S. (240 hly) 1Q214 12/4 240-hour maintenance Parafield
4/19/1943 C at 1 E.F.T.S. 1Q226 19/4 Parafield
7/28/1943 Allotted G?????? A/Wys. Ex 1 E.F.T.S. (for complete overhaul) 4MGQ112 28/7 Assigned to a civilian contractor for a complete overhaul Parafield
8/2/1943 Issued G?????? A/Wys. Ex 1 E.F.T.S. 1Q537 2/8 Shipped to civilian contractor
8/19/1943 Above allotment cancelled 4MGQ314 19/8 Cancelled
8/19/1943 Allotted V.I.A. ex 1 E.F.T.S. for complete overhaul 4MGQ314 19/8 Assigned to Victorian & Interstate Airways for complete overhaul
8/23/1943 Issued V.I.A. ex 1 E.F.T.S. 1Q605 23/8 Shipped to Victorian & Interstate Airways Essendon, Melbourne, Victoria
8/27/1943 Being ?????????? ????????? AID 27/8 Being worked on Essendon
9/10/1943 Fuselage ready for covering AID 10/9 Fuselage complete Essendon
10/8/1943 ??????? ???????????? AID 8/10 Being worked on Essendon
10/15/1943 B???g ?????? For test flights AID 15/10 Being prepared for test flights Essendon
10/25/1943 Received 1 AD ex V.I.A. 1Q860 25/10 Received at No. 1 Aircraft Depot RAAF Base Laverton, Melbourne, Victoria
10/25/1943 Allotted 1 E.F.T.S. ex 1 AD ??T644 25/10 Assigned to No. 1 Elementary Flying Training School Laverton
10/27/1943 Issued 1 E.F.T.S. ex 1 AD 1Q405?? 27/10 Shipped to No. 1 Elementary Flying Training School Parafield
11/1/1943 Received 1 E.F.T.S. ex 1 AD 1Q798 1/11 Received by No. 1 Elemtary Flying Training School Parafield
2/14/1944 E Star at 1 E.F.T.S. (240 hourly) 1Q119 14/2 240-hour maintenance Parafield
2/21/1944 C at 1 E.F.T.S. 1Q14? 21/2 Parafield
2/28/1944 ??????? Parafield aerodrome.  M/P ?? ????? 150% (-M/M/P ?? Upper 10%(M) O/S long’s (W) front interplane strut ?? ?? ???? Recommend A/F be repaired at unit 1Q175 28/2 A visiting Tiger Moth (A17-695) taxied head-on into A17-370.  There was damage to A17-370, but it’s difficult to make out the specifics.  They decided to repair it at 1 E.F.T.S. rather than send it to a depot. Parafield
2/28/1944 ?? ????? ????? ????? Rear 150% ?S An additional note on damage? Parafield
3/6/1944 C at 1 E.F.T.S. 1Q196 6/3 Parafield
6/26/1944 E Star at 1 E.F.T.S. (240 hourly) 1Q101 26/6 240-hour maintenance Tamworth, N.S.W.
7/3/1944 C at 1 E.F.T.S. 1Q138 3/7 Tamworth
10/7/1944 Transferred Storage Tamworth ex 1 E.F.T.S. QT814 7/10 No. 1 Elementary Flying Training School was closed on 15 September, 1944 having trained a total of 1,991 students.  It was converted into a Care and Maintenance unit on 12 December, 1944. Tamworth
4/2/1945 G at Tam. Storage T??160 Tamworth
2/25/1946 G at Tam. Storage ?????????? Tamworth
2/20/1946 U/S and stored as CMU Tamworth under Cat. D. (less cylinder head) CMU Tam. Unserviceable and stored at Care and Maintenance Unit Tamworth Tamworth
6/7/1946 Offered for Disposal ???? 2080 Tamworth
Sold by C.D.C. Ao Aust. Ass. Aero Clubs, 160 Castlereach St. Sydney – £100 ?990 922 / G(VIC) 922 Sold by the Commonwealth Disposal Commission to the Associated Aero Clubs of Australia for £100 (with a gaggle of others) Tamworth
10/23/1946 Issued to above Q101 Shipped to the Associated Aero Clubs of Australia

Abrasive Blasting Practice

image_20770I know that during the first year or two of the restoration I’ll be doing TONS of bead-blasting.  For the uninitiated, it’s basically sand-blasting except they don’t use sand anymore (very unhealthy).  Industrial blasters use mostly aluminum oxide which is pretty sharp and abrasive stuff.  Hurl thousands of bits of it at a hundred psi or better and you’re gonna do some damage.  Not only does it remove rust and paint but it can actually cut into the metal if you aren’t careful.  There are other media you can use that are more gentle on the surface such as glass bead or walnut shells.  I’ve used a big industrial blaster before and it’s fun but I really wasn’t ever happy with the amount of damage it did to the underlying part, even when I was being careful.  It’s a shotgun to kill a fly, most of the time.

image001So, I picked up a desktop-sized blasting cabinet designed for dental or small parts work (model 2100 VAB for the curious).  It still uses about 100psi but the grit it throws around is much finer, we’re talking down to 50 micron!  That’s the equivalent of 240 grit sandpaper.  You spray through a little “pencil” and control it with a foot pedal, it can recycle the grit or you can switch to fresh “clean” grit for, say, a final pass.  The next thing I needed was some rusty stuff to practice on.  That was nearly a problem, without outdoor storage (I’m an apartment-dweller) there isn’t a lot of rusty stuff around here, but luckily my boss at work has a carport that breeds rusty tools and he loaned me a few as test subjects.

Here are some before and after shots with my new toy.

2016-04-13 at 17.30.46 crop

2016-04-13 at 20.31.49

2016-04-17 at 15.00.11

2016-04-17 at 19.33.48

Very happy so far.  As long as the rust hasn’t pitted very deeply, the tooling marks from when the parts were made still show up.  These have a roughly similar amount of rust on them as the worst parts of the aircraft.  Of course that rust has accumulated over a longer period of time.  No predicting what I’ll find once I start cleaning stuff up, but at least I’ll know my blaster isn’t going to do any unnecessary harm.

Oh, and in case you’re wondering, after blasting I finished with a scotchbrite wheel and then some metal polish on a buffing wheel.  The surface left by even 50 micron grit is quite rough and unpleasant to hold.  This is with aluminum oxide, I recently got some 50 micron glass bead so that will be the next experiment.