thomas oliver 1

Further to my post re AM10 comp. screws, note that the larger AM engines have a 7/32in x40 tpi Model Engineer thread. T.O.

I have made quite a few comp screws for AM diesels in the past and the thread is in fact 3/16th in Model Engineering. T,O

I have just read the thread on the Mills 1.3cc . I would like to add my tuppenceworth. I have been using these engines since they were first introduced and have quite a few spare parts and engines. I have measured all the parts with proper thread guages. First the compression screw on the MK2 is 5/32 BSW. 5/32x32tpi BSW is close to but not identical to 4mmx0.75 pitch A 4mm screw will bind in the Mk2 cyl head. The carb needle on the MK1 is 1/8th in x 40 but the Mk2 is 6BA. However it appears that Mills did use at least one metric thread on the tank top fixing thread on the Mk1. A 4 mm nut will fit both 4mm and 5/32 BSW screws as nuts are always slightly loose on threads. Nuts are made dead to size with a tap, but screws made with adjustable dies are always made slightly below size to ensure a fit. Even small screws are usually a few thou.below the nominal size. The thread on crankshaft thread on the smaller 0.75cc is 4BA. As stated BA system was metric and of Swss origin and 0BA is 6mm x 1mm pitch but the angle is different. BA is short for "The British Association of Scientists" who adopted it for scientific instruments such as microscopes. .

Sorry, I was only allowed to do the daily inspections and there were RR civilian engineers who did the inspections and other work. I was not well up enough then to know exactly which system was used. The cutting out of the Merlin in a dive was due to the SU carb. used so I presumed that the injection system was to cure this, whichever one was used. The last regular job I did at Drigh Road, Karachi in 1947 was to check and service the intercoolers fitted between the supercharger and the main manifold, which contributed to the increase in power.of the Griffon engines. These were from Spitfire Mk22 and the engines were completely stripped after the first 30 hours. Cylinders were honed, main bearings were replaced and line reamed. The fuel systems were checked in an airconditioned separate bay, so I never saw what was going on with them.

Just let us get one thing quite clear. RR did not neglect development of fuel injection. I had 5 Sptifire MK 5s in my care at Millfield, Northumberland fitted with fuel injection and using 150 octane petrol, not the usual 100. This was heavily leaded and deposited a thick layer of brown deposit down the fuselage after a flight or two. The performance relative to the old MK1 and 11 at the unit was very much superior. Why they were never used in operations I cannot say, possibly because the Griffon was even better.

Allan, I have never visited Cosford since I did my course . I have a friend who is a member of the LMA and he has been several times to fly but i have always been otherwise engaged. Is there any of the old communal site left which had cinema, gymnasium, workshops etc?

I think it was at ED that all the lapping was done by one man - a well known West Essex club member called Len, using a Delapena honing machine. I have a friend who has made around 40 small engines - petrol and diesel, and he used such a machine. He is was elected as one of the "Motor Boys" on the MEW site. I made a copy of the female lap using slices cut off a Rolls razor hone and it worked quite well, but the male laps and the machine are complex. Making a one off engine means that maybe two or three pistons might have to be made, whereas the manufacturers could match up pairs from long production runs. I have several spare Mills l.3cc pistons and it is surprising the difference in the individual sizes of them. Edited By thomas oliver 1 on 24/12/2014 23:48:28

The manufacturers use metal dies to diecast the parts and this is not impossible for the amateur. I have seen a lot of castings made on Youtube and compared to my results they are rubbish, To achieve a good fininish on sand castings it is useless just shovelling in the sand over the pattern. It needs to be first dusted with parting powder using an open weave cloth bag, then the sand seived over the pattern with a suitable kitchen seive until completely covered, then the rough sand can be used to finish off. Also unless the melt is de-gassed with the correct chemical tablets there will probably be porosity. I cut out a cruciform shape in stainless steel and bent it into an open box. It then had a stem rivetted on with a ring handle. This was used to push the degassing tablet down to the bottom of the crucible. The consistencey of the sand is critical. When water is added, a handful of sand squeezed in the hand should just crack in two when released. Too much water and it will not. Too little and it will just crumble. One demonstrater on Youtube uses vertical extension tubes on runner and riser which increases the head and pressure and this is good pracrice. One trick I learnt is to prevent the runner from solidifying quickly preventing further feed, and this is to use a metal spike dipped in the top of the metal head in the runner and keep wiggling it. It is surprising how far down the runner will shrink and keep feeding to fill the mold. I always used Mansfield red sand and found it could be used over and over again. Oil bound sand tends to burn and go black, and all of it cannot be re-used. I hope these pointers will help beginners towards success.

On my first day at work up at the dispersal at Digri, Bengal in 1944, one of the things that immediately caught the eye were 4 huge pylons erected in a rectangle on the opposite side of the runway. Stretched between them was a single long length of wire rope supported by vee loops at each end. Below were a few small high wing cabin monoplanes with an arrestor fastened on top of the wing. These were in use each day to train pilots to fly in onto the wire then cut the throttle leaving the kite hanging, from whence it was winched down. The system was used in large clearings in the Burmese jungle to land VIPs and take out wounded One nuisance we had to attend to constantly were the Minor birds. They would collect twigs and quickly build a nest in the turbo charger outlet vent, As fast as we cleared them they would be picking up the bits and trying to build it all again. We had special covers fitted in these vents overnight. One day were heard some aircraft passing over to the rear. There were 3 Lightnings in line astern and very very low. The yanks were forever showing off. One lifted his nose over a clump of trees followed by the next one. The last one had pulled in too close and the prop wash hit him and forced the nose into the deck. He reared up vertically almost, stalled and piled into the ground. The tanks ruptured and it all went up in flames and was over in a minute or two. At other times we would hear the engines of a Superfort from one on of the 5 airfields in the vicinity. They Yanks loved to swoop down along our line of aircraft and put the screamers up us lot working up on the top. We would usually beat a hastry retreat down the rear of the wing and risk jumping to the ground, the Lib. being a lowish aicraft with its tricycle U/C.

The 1948 Mills 0.75cc had a machined crankcase similar to the MK11 1.3cc Mills, and could be machined from solid. Boddo also sold one like this - had one and is a cracker. Beware of the 0.375cc as it has a peculiar intake design and one model ea fitted with too big a carb bore. Grinding equipment is unecessary and engines can be made by accurate turning on the lathe. The biggest problem is getting a sufficiently good Liner/Piston fit to get enough compression. I have successfully made an AMCO 0.87cc and an Allouchery 1cc diesel. The fit has to be done by lapping - a black art. Nowadays the liner has a very, very slight taper down towards the top. Initially the piston should barely enter the liner and careful working it in with 400 grit silicon carbide should get a good fit and finish. It is best to make a lap which will expand paralllel, if possible. L. Spareys book has a good section on lapping. Lots of makes of engines had a cast iron liner and piston but Mills used hardened steel hence their long life. I have a 1.3 Series 2 MK11 which has done hundreds of hours of radio flying fitted with a throttle and it still has good compression.

Looks in good condition and has the thicker engine mount. The castings metal is very weak and the screw threads tiny so beware of dismantling. No where near as powerful as the later rotary shaft valve 100. I will make you a needle if you can send me a message with address,. I haven't a clue how to do this.

!59 Squadron :- Having described the health hazards, imagine working on top of the polished alloy wing of the aircraft in a temperature of plus 140 deg. with the heat being reflected upwards. We had to be supplied with special plimsoles with very thick rope soles to counteract this. Other special footwear supplied were mosquito boots with canvas tops and monsoon boots with canvas tops and rubber feet. We mainly wore open sandals and socks,. shorts and bush hats. Some bods sweated very freely and the sweat soaked into their shorts would slowly descend during the morning. I sweated very little and the crew got concerend for me so I reported to the sick room. A Sq. Leader doctor simply wiped his finger over my shoulder, and to my surprise he licked it. He declared that I seemed in the pink and not to worry. About spring I believe the monsoon winds started to perk up kicking up little dust devils. Then came the full scale dust/sand storms late in the sfternoon. It was not pleasant grinding ones teeth on a liberal sprinkling over your evening dinner. As the first rains arrived they were preceded by enormous swarms of all manner or insects, forcing us to shelter inside our mosquito nets for a couple of hours each evening until they sheared off, but leaving thousands of a sort of flying earwig which shed their wings onto the billet floor. The bearer would be called to sweep these up and burn them. Our nets became almost covered at times with these insects and what sticks in my mind is that a lot of them had rectangular bodies - very queer. After a week or two this rains increased and all these phenomena ceased, replaced by unrelenting rain. I was relieving myself behind the kite one day when suddenly appearing stage right were 3 Lightnings flying at very low level by 3 mad Yanks. No.1 pushed his nose up over some trees about quarter of a mile away followed by no2. No3 had moved in close behind him and got caught by the prop wash which pushed his nose into the deck. He reared up and stalled then crashed, rupturing his tanks and going up in flames. It was all over in a flash. We ran over but could do nothing. I still have an Open/Ring spanner which had been thrown out of a tool kit. There wer 5 Superfort airfield around ours and regularly one of these would appear, put his nose down and shoot up the row od Libs, scaring the s----s out of us. If refuelling on the wing one would shuffle down to the rear of the wing and it was not too high to jump to the ground from the trailing edge. At one stage when some of these Superfort Units were set up at Kunming in China, my squadron was given the task of ferrying petrol over the "Hump" to supply them. The libs were equipped with turbochargers which facilitated this, and auxiliary bomb-bay tanks could carry extra. The supplies for para-drops were loaded at Jessore north of Calcutta. It was the cholera capital of the world. I was sent there for a short detachment but of course we had jabs to protect us.

Incidentally Dave, I know Llanidloes well as my son lived in Llandinam till recently and is now at Rhyader. I have actually been in said museum.

Dave, Thanks for the encouragement. I have been prompted likewise when I posted my experiences with the Lancasters of 617 and 9 Squadrons when they came to India as part of Tiger Force after the European war ended.. I can assure you that I had some shocking and quite a lot of pleasurable experiences, but my memory is getting worse by the month now. I flew on a few ops. as a stand-in Flight engineer and once had a wonderfull months leave in Srinagar up in Kashmir. The journey there and back is story in itself. I had first hand experience of flying a Lib and taxying one, as the routine of operational flying out there was really deadly boring, and the Pilot would usually have one take over for long spells as a relief. Flying from Bengal over the Indian Ocean then over the oceans of trees in Burma was not what you would call exciting.

159 Squadron.;- At the time I reached Digri in Bengal, the Japs were on the retreat from Kohima. The Lib.squadrons were then engaged in knocking out all the bridges to prevent the retreat and cut the supply chain. They also kept our ground troops supplied by para-drop. The crews had some hairy times climbing out of valleys after a drop. Incidentally, earlier one aircraft from 159 crashed in south Burma and the Japs beheaded the crew. This is all in the squadron records. I have a good few aerial photos of the effectiveness of the bridge hits as every bridge had two or three pontoon briges built on either side and all trashed. Those of you who have never left the shores of this green and pleasant isle can have little conception of what had to be put up with out there. Nasties included an ever present prescence of kite hawks, waiting to swoop on unwary bods. leaving the dining hall and neatly snatch the scraps from their plates. Snakes, scorpions, 6" centipedes, giant ants, insects, huge swarms of insects, - stag beetles 2" long were encountered. One member of our crew was bitten by a huge centipede causing his hand to swell like a balloon. While untying a picket rope I got stung by a scorpion, which felt as if my finger had been bashed by a big hammer. I spent two days in dock sedated and was nearly blind for three days. Health hazards were "prickly heat" which we all got at first -a very itchy rash, I once encountered a large Russels Viper, but I was lucky and had a dipstick in my hand and swiped it across the neck. Bengal foot rot which I got Skin diseases like ring worm . Bruce on our crew had 5 different diseases at once and had to be sent home to Blighty. Heat stroke - 3 members of our flight went away to hospital almost "Round the Bend". In spite of all this work and operations went on and 159 received an accolade from Group for achieving the highest serviceability record in the history of the RAF.

Following are shots of the type of RAF thatched billet and dining hall at Salbani, Bengal 1945.. Roof fairly effective heat shield and reasonably waterproof in monsoon rains. One of my charpoy (bed) and home made furniture. The group are all the ground crew who serviced aircraft C, with NCOs at front.