Norcim rc electronics club page 25……
SOME FURTHER EXPERIMENTING AND NOTES ABOUT HOME ANODIZING. By David Caudrey. (See also Page 16 for basics).
<<<First picture is an early PAW 15 diesel with dark blue (Plum) home anodizing.
1) For a cylinder barrel the size of a PAW 19 between 0.8 and 1.2 Ampere hours is about right. (If one overdoes it the anodising is too hard and won't take dye).
2) Another problem is how to suspend the barrel in the anodising bath using the compression screw hole (2BA for old PAWs). Current tends to favour the suspending conductor and, if ferrous, to erode it rapidly. Initially I used a steel bolt or stud hanging from a short length of stainless steel bicycle spoke which effected depth adjustment by virtue of the nipple and thread. I found that, if wetted, the spoke soon disappears allowing the barrel to fall to the bottom of the bath. However keeping the suspension spoke dry doesn't help with regard to current favouring the steel bolt and eroding that. What is needed is an aluminium bolt or stud. Not having any suitable rod to make the latter I was lucky to find a 2BA titanium bolt stemming from the days when Britain made aircraft. This did not erode but it still took a significant proportion of the anodising current. A heat shrink sleeve over the portion of the bolt in the acid overcame this problem.
Second picture showing Light Blue home anodizing on a PAW 19 >>>
3) The dyes I use are Dylon hot water fabric dyes and it seems that there is a degree of temperature dependence involved. For a red or navy dye just above blood heat 40 degrees is fine but I had to raise the temperature to 60 degrees for blue to take. Note that it is important that the dyeing temperature is well below 100 degrees otherwise the anodising will seal and not take dye at all. With regard to the latter it is important that the anodising bath is large enough for the temperature not to exceed the dyeing temperature. My early efforts using a small polythene bath with a carbon cathode resulted in poor dye take up due to pre sealing.
Attached is a photo of the PAW 35 Redhead which I class as a failure. I gave it 2 A-h when I should have given it 3 or more, taking account of the surface area.. The result was that the dye did not take strongly enough for the colour density I was aiming for. I returned it to the anodising bath for a further half Ampere hour after which the dye penetrated but not uniformly.
<<<Third picture showing results with a PAW 35 diesel engine.
(PLEASE REFER TO PAGE 16 FOR MORE DETAIL OF HOW TO SET UP FOR HOME ANODIZING)
<<<This picture shows the anodizing bath used for the above home anodizing. It is a stainless steel ‘Greek Kettle’ but any similar pan could be used.
The barrel of the motor is suspended from a teak beam. The PAW 35 barrel has not come out well but returning to the anodising bath for a further 0.5A for an hour did persuade the dye to take better. I should have calculated the surface area instead of just assuming that it is about double that of the 2.5 and 19 barrels. Crock clips are used to attach the variable current flow to the top screw (positive) and the kettle (negative). See also page 16 for more electrical info. Note that aluminium pan containers have been tried but do not take as well to the acid.
Attached is a photo of my attempt to anodise the barrel of an Indian Mills 1.3 cc green. The only green dye available is very dark and undoubtedly was not going to give a bright finish but the results are worse than anticipated.
Firstly the barrel came out blue instead of green and, because it took up dye instantly rather than progressively as has been the norm for other dyes, it is consequently much darker than intended. Making use of this characteristic the spinner nut was left in the dye for longer such that it 'matches' the black prop driver. It is possible that the metal used has some influence on dye take up and the particular engine does not give the impression that rigorous quality control is involved in the selection of manufacturing material. Having said this, it looks like a Mills and it starts and runs like a Mills.
I tried to dye the barrel of a spare ED Cadet green. This was a complete failure because the dye refused to take and so I washed it off and dyed the barrel red. The result is shown in the attached photograph with a standard ED Cadet for comparison. Some might call it sacrilege because the Cadet is rare and sought by collectors but the one I have anodised is kept for spares and requires a con rod; having been cannibalised to keep a MKII Ed Bee running. The ED Cadet is rare because it was a complete failure, having little power and being almost impossible to start; which is astonishing for a side port aimed at ease of starting. It was sold complete with silencer which I believe is very effective if you can get the engine running with it. I have only managed to get the un-anodised one running without the silencer. Even then it is much quieter than an ED Bee.
With respect to starting and running, I might have been
unfair to the Cadet. Subsequent to the anodising experiments I decided to
attempt to get the complete engine running with its silencer fitted. In fact I
found that it could be started quite easily using a method which would not be
applicable to most model Diesels:- With the
compression slackened off by half a turn or so from the running position, the
propeller is flicked with a finger sealing the air intake. Rather surprisingly
the engine fires quite readily in this state but, once running, the compression
needs to be increased quite quickly to keep it running. Progressively closing
the needle valve to lean the mixture and increase the speed has little effect
(the engine will not run fast even on a 7X5 prop) other than to stop the engine
I adjust and start model Diesels engines by entirely by feel and I instinctively know when engine is about to fire. However the Cadet is completely devoid of feel and gives no indication whatsoever that it is ready to fire. ‘Fired’ by my success in starting the Cadet with its silencer fitted, I decided to make a Dural con rod for the spare (red) engine and to apply the same starting technique. This was successful and consequently I have now two ED Cadets which can be made to run ever so quietly but, to quote Mike Clanford, “Haven’t the strength to pull the skin off a rice pudding!”
During this investigation I noted that the engines have different porting arrangements so presumably ED. were trying to optimise porting during production. Neither engine is stamped with the ED manufacturing code so I have no idea as to which is of later manufacture.
The larger of the two engines in this picture is the UK ‘ED Racer’ 2.46cc with the home anodized red barrel mentioned in page 16. The Racer diesels were a very popular engine in the 1950s/60s and thousands were manufactured. Alongside is a superbly made one third scale version of the popular ED Racer with a capacity of 0.78cc. The crankcase of this little beauty appears to be die-cast unlike the original which suggests considerable tooling for that part alone. As can be seen from the picture and mechanical observation with removal of the back plate, all parts are to the highest standard.
Despite some digging into the history of this little engine, I have not yet traced the manufacturer or the country of origin.
The experiment to anodise the cylinder barrel of the MVVS 1.5 cc engine gold has met with limited success.
In my experiments it has become apparent that some aluminium alloys anodise better than others. For example some articles come out of the caustic cleaning bath bright and shiny and these seem to anodise and take dye well. Others come out an attractive gun metal colour which is removed by the anodising bath.
However I believe that it is durable if not immersed in sulphuric acid and it could well be a simple alternative process for some alloys. Parts which come out from the caustic bath gun metal grey do not appear to anodise or take dye readily. Anyway the MVVS barrel emerged from the caustic bath gun metal grey so I was not confident of success. After anodising for an Ampere hour I removed the barrel, washed it, and suspended it in yellow dye. It appeared reluctant to take dye so to cut my losses (and avoid tedious mechanical stripping) I returned the barrel to the anodising bath while I warmed up some of my faithful red dye. To my surprise the red dye failed to penetrate - possibly because the surface had sealed already - so I washed off the red dye. When this was done I realised that the yellow dye had in fact taken to a degree and that the barrel was in fact light gold in colour.
Attached is a photo of my very rare Indian Mills 0.75 Green Head. At last I have had some success with green. Presumably the barrel of the 0.75 is of the same alloy as that for the1.3 and, remembering the peculiar colour the latter turned out when I tried to anodise it green, I decided to try another dye. The only green other dye I managed to source from the late lamented Woolworths was a cold water dye. Cold water dyes are not thought to be suitable for anodising but I decided to give it a try. At shed temperature there was absolutely no take up of dye so I raised the temperature to 45 degrees. With the warn dye there were perhaps signs of feint greenish tinge but it could well have been imagination and so, in desperation, I poured a little of the original 'green' dye into the dyeing vessel and bingo it took. I will call a halt engine anodising now as green was the ‘holy grail’ colour. Red is easy, blue needs a little more application and green has eluded me up until now. Yellow/gold I'm not sure! The little 'Mills' is of poor quality despite that it starts like a Mills and runs like a Mills. The crankcase is also porous and after a run is covered in froth.
_______________________thanks for reading! DC 2017________________________
SIGHTINGS ARE BEING REPORTED OF A ‘SUPERMAN 2’ OVER THE MARKET TOWN OF HUNGERFORD
AND THE BERKSHIRE DOWNS, UK.
It is believed that SUPERMAN (Clark Kent) had a twin brother. Both were sent to Earth before the planet Krypton exploded. Their father sent them separately hoping that at least one of them would survive and be taken in by Earth parents. The brother was taken in by the Green family in Hungerford who named their new son Rob (Robin Green).
It is only recently that Rob discovered his superior powers allowing him extra ordinary skills including the ability to fly!
Sightings of SUPERMAN 2 have been circulating the web as confidence is gained at flying speeds over supersonic. (Pwew!)
By day Rob Green remains a member of the Hungerford Model Flying Club specializing in Radio Control of amazing flying objects.
If you fancy rearing your own superman as part of the
family then you will need sheet Depron foam with
suitable carbon strip reinforced limbs, a little plywood,
brushless motor, LiPo battery, ESC, RX and acrylic paint.
Further details are available from the original designer and builder Otto Dieffenbach from USA https://www.rcgroups.com/forums/showthread.php?1838627-Flyguy
He flies very well if a minimum 3/4 throttle is maintained and although he has only taken to the air 5 times is proving to be well behaved and gaining confidence with his new found powers.
Many Thanks Rob !
AN INTERESTING ELECTRONIC PROJECT FROM GEORG BOHMEKE FOR USE WITH INDOOR FLIGHT….
Georg has a great interest in indoor flying and often living in Germany where building your own Radio Control transmitter is banned, he came up with an interesting alternative for his indoor flying. Infra-Red transmission is not banned (it’s commonly used for changing channel on your TV, Audio system, air condition unit, etc). The idea for indoor flying is simply have some control over the model to avoid the model bumping into walls.
Georg’s transmitter is a DIY experiment using a DIY Infra-Red transmitter based on an EU ‘self-certified’ CE toy import from another country. The IR transmitter originally controlled a tiny toy car requiring only a few feet range. To increase the range suitable for indoor flying, it was necessary to replace the single LED of the toy controller with 15 LEDs!
‘’To overcome the problem of being a terrorist when making an own RC equipment, I have experimented with infrared. Here are some photos of my "bit-charge" system (in the USA they call it this way). A simple toy was used as basis and the transmitter enlarged from 1 LED to 15 LED's. That should give nearly 4 times the range. I also made an IR- transmitter with 60 IR-LED's and can feel the signal on my skin, becomes slightly warm. All was stopped when I had to go to India, then Korea, then China with my business. I advertise my one-man consulting company and live presently in China (officially in Finland) but, to my remembering, I have been a German ;)
The king of IR -control is probably Koichi Tanaka from Japan:
(I cannot open his page here in China)
Have a look at my Indoor Flying Club >>>>https://www.youtube.com/watch?v=opCeCMwqCzs
Big Thanks George .
One of Georg’s electric gliders is shown which often gave over an hours flying time with simple brushed motor and an NH battery pack.
The prop of the glider
was a D=16,5" P=15" unusually large, close to Wakefield or CH. The
weight was 1200g and of that was 350g of Batteries. The Speed-400 had
a 7,2V winding and was thus matched to 8 cells. The planetary gear
with 3 planets had a gear ratio of 1:6. Current in stillstand was 6-8A
and in flight probably around 5A. That makes 5 x 8= 40W of electric
power and the simple Speed 400 converts this to ca 28W of mechanical power. Taking off 3 W for the gear, we have about 25 W of propeller
power. The efficiency of the prop might be 0,7 and we have 17,5W as propulsion power. I have made same calculations regarding aerodynamics
and propellers etc. It is part of my core competence for wind power rotors.
GEORGE ALSO SENT DETAILS OF A VERY EARLY FOUR SERVO PROPORTIONAL MODEL CONTROL SYSTEM DESIGNED BY HELMUT BRUS.
The picture to the right shows Helmut’s transmitter which was way ahead of its time. The 27MHz band was used with four tone generators being multiplexed to provide variable voltage inputs to the four analogue servos. There were no ‘servos’ to buy at that time at that time so Helmut produced his own based on the Siemens TO5 industrial electric motor. All details in his book.
Looking at the picture, there is a leather neck strap hidden behind the transmitter box. (The transmitter was heavy) The tallest item from the top of the box is a telescopic centre loaded aerial (around 1.2Metres extended). Next item the triple axis control joystick. Forward, down elevator. Back, up elevator. Left, aileron. Right,aileron. Twist the knob for rudder control. Throttle speed control on the left small lever. There are other in flight trim rotary wheels in the top surface. A magic start to R/C transmitter control layout.
Georg helps out now with translation problems :
Yes, it is basically a dead-end road based on thinking all time, that
R/C has certain modulation frequencies. And not pulses with the
Information hidden in pulse distances.
The schematics tell the function: four modulation frequencies are
multiplexed, and each of these modulation frequencies is varied around
a middle frequency by some plus-minus margin. The receiver works like
a ‘ratio-detector’ in a radio: Two resonant tuned circuits are coupled
and rectified in such a way that the signal hits the flank of either
resonant tuned LC circuit. The output is proportional DC. Then a
simple differential amplifier with a pot coupled to the servo
converts to a DC to position.
Yes, the servo motors were Faulhaber ironless bell-armature motors. I
still have one. The efficiency is very high, they run smoothly and can
run on a single solar cell with just 0,4V. They are expensive due to
many detail reasons. But the high efficiency justifies them where
battery mass is crucial. The Mars robots have similar motors in their
Helmut produced a book around the time which gave complete construction details of his R/C system for his fellow ‘Soldering Set’ modellers around the world.
Thanks for reading!
DAVID’S STORY OF SAVING A SAD ENGINE DONATED BY A MEMBER OF THE HUNGERFORD MODE FLYING CLUB.
The engine was identified as a Dav Cal Dart 0.5cc diesel. It was in a sorry state, completely solid but signs of something ‘not quite right’ inside.
The solidly gummed up Dav Cat Dart with a broken con rod was given to David to see if he could do anything with it. As it was complete with box and documents he thought it might worth a try to produce a replacement con rod and, having successfully hand fettled a Dural con rod for an ED Cadet David thought a similar exercise for the Dart it was worth a try. As shown in the rather blurred photographs the exercise was successful. The central picture shows the con rod as roughed out and attached to the piston prior to fitting into the crankcase for clearance testing. (At half stroke the con rod, if too thick, fouls the bottom of the cylinder and it is necessary to remove the minimum of metal from the right areas to obtain clearance without compromising strength - cut and try process for a hand made item). When the engine was reassembled the piston was found to be too tight in the cylinder bore and it was necessary to produce a crude hone to clear solidly gummed up castor from the surface of the bore. Once freed the Dart was found to be easy to start and an attempt was made to take photographs of it running. The first photograph was taken inside with flash; which resulted in the prop being strobed stationary. To avoid this the third photograph - an attempt to get a picture through the prop disc - was taken outside on a dull day without flash. The apparent vibration is thus due to camera shake!
When the picture was taken the Dart was running at about 13,000 rpm. on a nominally 6"x 4" prop.
Dav Cal engines were made in the 1980s at the end of the long Allbon/DC story. They seem to be characterised by ‘anaemic’ anodising of the aluminium cylinder jacket. David thinks that they were perhaps not up to the high standard achieved by Allbon/DC possibly with regard to heat treatment because he has two Dav Cal 1.5cc Sabre engines which sheered their crank pins when running.
Thanks for reading!