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Old Mar 19, 2011, 08:48 AM
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>In some countries like the UK, just after WWII they had restrictions in place as well, for example you were limited to a max of 45 seconds of engine run time

I never heard of that in the UK - perhaps elsewhere; however, the flying of gas models was prohibited during most of the WW2 years.
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Old Mar 19, 2011, 09:14 AM
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Originally Posted by JohnAV8R View Post
...The Atom (1.8 cc) specs listed a 12x5 prop at 6500 rpm!...
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Originally Posted by earlwb View Post
...
Now some people in another thread were commenting that the 1.8cc Atom replica seemed to be outperforming the larger 2.5cc Letmo replica as well...
6500 rpm on a 12x5 is pretty good for a 1.8cc engine!
My (silenced) Taifun Zyklon 2.5cc yields 7300 rpm on a 11x4 with plenty of pull!
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Old Mar 19, 2011, 12:51 PM
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Originally Posted by Applehoney View Post
>In some countries like the UK, just after WWII they had restrictions in place as well, for example you were limited to a max of 45 seconds of engine run time

I never heard of that in the UK - perhaps elsewhere; however, the flying of gas models was prohibited during most of the WW2 years.
I was actually reading it in a old copy of a article from 1945 with a review about some model diesel engines and ignition engines from that era. It might have been one of the articles posted in the Vintage Glow Plug engine thread here on RCG. The author was explaining the techniques involved in starting and running a engine on a FF plane. You would get the engine to start, adjust the needle and or compression, top of the fuel tank, check the needle again, top of the fuel tank, get set to launch and maybe top off the fuel tank again if you had to wait too long.

I also remember reading where the British Ministry rescinded the petrol restrictions in December 1945 which made a lot of modelers happy.

I ran across this article where the author mentioned that back then FreeFlight engines generally didn't run for more than 20 seconds. http://modelenginenews.org/ad/drone.html
When control line came out it began taxing the limits of the ignition engine technology at the time. Battery depletion, etc. So the small diesel engines started becoming very attractive in comparison to the ignition engines. Of course in a couple of years the glow engine wiped them out almost overnight in the USA.
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Old Mar 19, 2011, 12:58 PM
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Does anyone know if anyone came up with plans on the Drone .29 single ball bearing diesel engines that one could get a copy of, by buying or otherwise? I have a set of castings, and it might be neat to try and make a replica of the engine. I know I could likely make some good educated guesses as to the dimensions for the parts. But before I go that far, I thought I would ask about first.
Thanks
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Old Mar 20, 2011, 07:48 AM
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building a first time model diesel engine

Earlwb, I can’t help you with your request, “Does anyone know if anyone came up with plans on the Drone .29 single ball bearing diesel engines that one could get a copy of, by buying or otherwise? I have a set of castings, and it might be neat to try and make a replica of the engine”.

I think my “little” brother “Ted” is going to be wanting to talk with you. I got him an old 1935 lathe about 25 years ago. Yes, it’s taken a long time time, but my brother is looking at building a first time engine as shown on Ron’s Model Engineering site under the following link,

http://modelenginenews.org/ed.2007.04.html#6

where the object in question is to build a 1.5cc model engine made from bar-stock! The idea behind this design is a beginners' engine designed to incorporate all the things which Ron discovered by investigating other engines for the first-time builder. The design can be built for glow or diesel ignition, with rear-rotary or reed valve induction. All options are also convertible and interchangeable.
John
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Old Mar 20, 2011, 03:18 PM
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Originally Posted by JohnAV8R View Post
Earlwb, I can’t help you with your request, “Does anyone know if anyone came up with plans on the Drone .29 single ball bearing diesel engines that one could get a copy of, by buying or otherwise? I have a set of castings, and it might be neat to try and make a replica of the engine”.

I think my “little” brother “Ted” is going to be wanting to talk with you. I got him an old 1935 lathe about 25 years ago. Yes, it’s taken a long time time, but my brother is looking at building a first time engine as shown on Ron’s Model Engineering site under the following link,

http://modelenginenews.org/ed.2007.04.html#6

where the object in question is to build a 1.5cc model engine made from bar-stock! The idea behind this design is a beginners' engine designed to incorporate all the things which Ron discovered by investigating other engines for the first-time builder. The design can be built for glow or diesel ignition, with rear-rotary or reed valve induction. All options are also convertible and interchangeable.
John

I have been thinking about building the BollAero 1.8cc myself: http://modelenginenews.org/
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Old Mar 20, 2011, 03:44 PM
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The windy west coast of Sweden
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The mysterious propdriver

Hello,

Does anyone recognise this small propdriver ??

It may be British, as it came in a bag of other British engine bits, years ago....(though this is just 'circumstancial evidence')
It does show similarities to the ED Baby propdriver, although this one is a tad larger (still small, though).
The measures are not at a 'scientific' level, but close enough.

Please don't spend too much effort, as I'm not desperate...just curious...

Who knows, it might get identified by someone who needs it...


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Old Mar 21, 2011, 04:52 PM
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The Good, The Bad, The Ugly - Part 1.

Hi,

I guess this situation is familiar to many engine freaks…
You come across an engine with some spares.
Eventually those ‘spares’ start to grow into a second engine.
In the process, you collect even more ‘spares’, eventually leading to a third…and so on….hence this trio of Frog 50’s that still keeps me busy…
(this is a slow process that has taken years, still running)


The Good (1)
It has good compression and looks pretty neat. I would consider it ‘finished’, though I still keep it loosely assembled, should some ‘better’ components turn up.

The Bad (2)
This one has yet to be completed. It misses propdriver, carb needle and the original backplate. At present it has a ‘radial mount backplate’, which probably is home made (good though). Additionally, the fins etc need some tidying…

The Ugly (3)
It is not that bad…I would consider this one a ‘good one’ in an ‘ugly’ disguise….some tidying, and it’s as good as No 1.

(all 3 seem to be MkII’s, as the NVA's are 90°, i.e. not swept back)


So, an engine plus ‘spares’ becomes two engine plus ‘spares’, now slowly growing towards three……..time to stop….?...no, not yet…


The Cavalry comes to rescue….
To keep dwelling on the initial theme, for a fistful of dollars….I just came across a very sad Frog, although beeing a suitable donator of backplate and propdriver. Also the needle valve, well at least the important threaded sleeve, is there…
Hen’s teeth…?...yes, in a way, as these things start to get real rare….to me this little 'piece of junk' is a treasure, fitting right into my project...

Now take a look at the donator engine….it seems to be a MkI, as the finned head is considerably lower (more pics of that later on). Also the compression lever is a ‘single bar’ type, its threads being of a narrower dia than the T-bars of the other engines….hmm, thinking..…NO WAY…..I will stop here and set 3 good Frog 50’s as a goal…life is too short, and I really don't need that many Frog 50's...eventually I may sell or trade one or two of them away....




To be continued, although it may take a while…
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Old Mar 21, 2011, 06:28 PM
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Mt Evelyn, Melbourne, OZ
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Hi Gluehand
I think those 50's are all MKI's.
The MkII had a strap type crankcase presumably to allow a larger conrod big end.
The MkIII then added the swept back needle.
I could be wrong however.

I have a MkI which runs quite well, but appears a little less powerful than my ED 0.46 or ofcourse the Darts.

So have you run the Schlosser yet?
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Old Mar 21, 2011, 08:28 PM
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Gluehand, if the compression is still good in the “donator” engine, then it might still be a good runner. The rod bottom looks good from what little I can see. The broken lug could be built back up with weld. The fins could be straightened out as best as you can, then perhaps lightly re-turn (lathe) the surface to freshen it up. Yes, it will be slightly “thinner” and smaller, but “fresh’ looking. Yes, that .5cc is indeed very compact. Very good pictures, just like a pro.
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Old Mar 22, 2011, 03:41 AM
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Warren,
Thanks for the correction...I didn't do my homework thoroughly...
It appears there were 2 generations of MkI, i.e. the first version featuring the shorter cyl.jacket. I've also heard about a 'mythical' single-ended comp.lever which should have existed on a very early production run of MkI, although this has yet to be confirmed. Adrian Duncan mentions this in his article in Modelenginenews...
Interestingly, my 'donator' engine features the early 'short' jacket, AND a single-ended lever. Home-made...?..it's doubtful, as the thread of the lever, as well as the hole in the cyl.jacket is a smaller dia, compared to the newer jackets/levers...any bodge by some owner would obviously have resulted in an unaltered or larger thread dia...
Significant for MkII is, as you mention, the 'strap' type crankcase (and also, later on, the swept back NVA - or was it MkIII...?).

The little Schlosser: There will be a test run...first I just have to find that 6x3 wood that I KNOW I stashed somewhere...

----------------------

John,
Yes, as I have yet to investigate the 'donator', the internals may well be in good shape. Nothing speaks against it so far. A gentle heat-treatment will loosen things up and we'll see...
The crankcase: These days, alu-welding is a realistic option. For instance, I've heard lots of good things of 'Unisolder 390' (I have seen very neat exhaust manifolds etc made with this mix of solder/flux).
In the event of completing this engine, an option would be to use the 'radial mount backplate', which is really neatly made...

Question is if I really wish to enter a fourth Frog 50 project.......concentrating my efforts on the original 'trio' feels more realistic to me at the moment....
Should you, or anyone, be interested in such a project, feel free to get in touch...


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Old Mar 22, 2011, 06:55 AM
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Quote:
Originally Posted by JMP_blackfoot View Post
Well, mine shows a very similar front end
They can't all have been made on that fatal Friday afternoon
At least, it shows consistency...
Chas, JMP,
What is the problem w/ the irvine mills front end driver and cylinder lining or crank?
Thanks
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Old Mar 22, 2011, 12:06 PM
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Originally Posted by RocketRob View Post
Chas, JMP,
What is the problem w/ the irvine Mills front end driver and cylinder lining or crank?
It has been noticed that the crankshaft is not centered in the casting. It seems to sit a bit high, as can be seen on the photographs. This has raised concern about the height of the cylinder relative to the crankshaft, with possible impact on the timing of exhaust, transfer and intake ports.
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Old Mar 22, 2011, 04:34 PM
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My CS replica seems fine. Perhaps the problem is only with the "originals" ?
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Old Mar 22, 2011, 09:11 PM
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You know, I remember the British doing some odd things manufacturing things. Especially with my British Motorcycles. Maybe the connecting rods were made a tad too short, so they offset the crankshaft to compensate on a batch of engines. It was better than scrapping the lot, especially if you had customers waiting.
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