Aha-the old wooden cable drum test bed trick......the most convenient test stand ever adapted by man.........[they make handy outdoor barbeque tables and seats as well-in the appropriate sizes]. Nice quiet motor-I'm surprised they didn't make bigger inroads into the US stunt scene when they were around..........

ChrisM
'ffkiwi'

Actually the Drone engines were hugely popular at first. They pretty much dominated the control line competition events for about 2 years. Just about everyone had to have a Drone engine to compete. Plus everyone else wanted one for sport flying too. I remember guys telling me how they would see a fellow show up, fuel up his Drone powered plane and go flying, refuel and fly, and so on. No problems no hassles. All the while everyone else was struggling to get their cantankerous spark ignition engines to run so they could make one flight for the day, at least. They would give up and get a Drone engine too.

But alas the advent of the glow engine hit the market and just took over almost completely in rapid order. But I think for 1947,1948, and 1949 maybe into 1950 the Drone engines were the engine to have if you wanted to fly at the time.

That was back in the good old days, when a flyer could go to the local pharmacy with their fuel container and the pharmacist would top it off with ether for you. You would add the oil to the container and the pharmacist would pour in the ether from his big container. Nowadays ether is tightly regulated.

Unfortunately when glow engines took over they really took over and dominated the market almost completely. Pushing out gasoline spark ignition engines and model diesel engines.

GOT IT TODAY very stiff on turning hit with some WD40 a rinse insidewith some davis abc fuel it came with a topflight 10 inch pitch not known stuck it on the bench about 10 flips and a very loud bark a few more flips with some davis fuel and ran for a few seconds loud sounded like an AK 47 it needs a needle valve assembly and a rear gasket between tank an crankcase, that I can make up I would guess any c/l needle assembly would work very very stiff crank and rod ok no slop in either would ne nice to do a real run will have to scout up a drone needle or replace the whole thing, its been sitting for about 60 years

one of the extra crankcases has an intact c/l fitting so if I can find a needle will be ok

Hi Martin,
I've been playing with, and flying, fixed compression for decades. Could I make a few respectful comments...
1. I've read all sorts of conjecture concerning fuels... There'sno need to get bogged down in assessing variousfuel mixes... Just make up the recommended Drone fuel 75/25 (this was the original Micron recommendation, in 1943). This fuel will be OK in any temperature between about 20°C and 30°C. Below 20°C (unlikely in Fla.), you may need a bit more ether (80/20 is OK because inthe lowerambient temperatures, you won'tbe overheating). Conversely (andmore likely in Fla.), above 30°C, if you don't reduce the ether content slightly, you'llget pre-ignition (combustion will occur before TDC), which results in very rough running and vibration. IMO,this is why some people find that Drones vibrate, they just have too much ether in the fuel. So in the high temperatures that you have in Fla., in summer, you may well do better with 60/40 fuel, or even 50/30 with 20% kerosene. Personally, I always use 75/25 and just avoid using the engines in very high or very low temperatures (otherwise, you're continually messing around changing things).
2. Your NVA issue is a non-problem. Just borrow one that fits (no air leaks and with the hole roughly in the middle of the venturi) from another engine. In the States, I think the old Austincraft "universal" NVA would be an excellent solution.
3. Concerning the photo you've posted. If you've never run that engine before, and you're not experienced with fixed compression, then the prop on the engine looks to be far too small. To run a Drone/Micron etc. for the first time, always start with a 14x6 wood prop (another Micron and Drone recommendation!). When you get used to the engine, then you can start to experiment with other props. TheTopflite 14x6 wood is great for flying old timer RC so, for me, there's not much point in playing with smaller sizes, it just complicates the issue and would only be relevant if you intend to fly CL...
4. One potential issue is that we're communicating internationally, and between very different climates. Fixed compression diesels are very "temperature dependent", and opinions that are valid in one part of the world won't necessarily be valid elsewhere. In the warmer temperatures of the southern US, there shouldn't normally be any problem running fixed compression. However, in cold climates (Alaska, Norway, etc.), there probably won't be many days in a year on which a FCD will start easily and run well... One "advantage" of being in Europe is that we're half-way between these extremes. We get both types of climate, so I see those changes in running characteristics, twice, every year!
Brian

HI Brian .THX for your advice on this one I was surprised when I took it out of the box and saw the small 10 inch prop with it will go get the larger one biggest one I have now is a 13x6. Back when I was a kid the drone was my first and only engine I had and did make up the 75/25 fuel mix, it brought back memories never an issue with it as I recall over many years an moves it sadly went missing martin

the small prop wth it appeared to be a pretty high pitch maybe a 10x10?? or higher pitch?? if they made them back then

I was out of this hobby for decades when I started again my first engine Irvine 40 diesel and then of course other diesels never bought a glow battery till I got some 4 strks
my davis conversions contrary to custom never saw glow fuel no issues ever it just took a few more tanks to break in no diifferent glow fuels plugs to match etc

Martin, I think the 10x10 prop wouldbe good for CL, but IMO it just isn't the easiest to get to know the engine.
What I wrote above, I'm sure of!
But the following is just my opinion, I've never used American commercial fuels.
I get the impression that there are commercial interests involved. Calling diesel fuel "1/2A fuel" or "ABC fuel" implies that you need various different diesel fuels for different engines, which just isn't true, except for fixed compression.
Consider the situation of making up your own fuel, which is all the commercial guys are doing. If you have enough ether content and enough oil content, then any variable compression diesel will run on it. The fact that you may be able to get away with a little less ether or oil, in certain engines,doesn't justify making such a fuel if the basic fuel runs the engine OK. IMHO it's just naughty commercial practice aimedat people who aren't familiar with diesels. It's a logic of "why sell one can of fuel when we can sell two!" It's perfectly possibleto makeone fuel blend that suits all variable compression engines... I'm a life-long diesel lover, and it makes makes me a bit cross to see people inventing constraints and requirements thatjust don't exist.
Apologies for the soapbox!
Brian

Brian interesting point on commercial fuel blends think the Davis 1/2A was made for Cox conversions originally and has favor in a lot of small ones higher ether and oil content
Model techniques in the UK has 3 blends If you look at the instruction sheets MVVS, PAW. etc they re all over the place on mix ratios if you have oil out the exhaust you have enough
lube
I just find it easier to use the Davis blends no messing with mixing
Nice thing about diesel if you go too lean it just slows down and stops a very lean run on glow hot, not enough oil and damage likely
about the only way to ruin a diesel is running overcompressed or hydro lock it martin

Think there is a low limit on oil % for long life I would not go lower than25% ( my thought)

Well the Drone engines were setup up originally for control line stunt using s 11x10 prop. Drone used to sell the 11x10 prop for the engines too.
With the fuel, I was using in one of my Drone engines, a 12x8 felt a little bit under compressed and a 13x6 seemed to be about right. So I was planning on trying some other props but didn't get around to it. I was thinking that a 12x9 prop would probably be correct and maybe a 13x7 prop too a 14x6 might do the trick as well. Since the engine doesn't rev up high, one would have to use a 11x10 prop or equivalent to get the air speed up for control line flying.

In case some people peruse this thread and want to find more information about them.
Adrian Duncan of Model Engine News wrote this most informative article about them http://www.modelenginenews.org/ad/drone.html

Here is a couple of one page magazine articles about the Drone engine from way back then.

Drone Diesel Decal

and the other one!

Charlie Bruce on Drone diesels

V HEAD for Drone by Jack Bayha

The Drone had it's appreciators outside of the US.

Here are a couple of Australian "Drone Copies".

1. The G.B. Stuntomota

2. The A.E. McCullough Red Special.

Sometimes the adjustable compression diesel heads show up for auction of for sale. Or one can make one too.



and they had glow fuel heads too with a threaded hole for glow plugs.

OK guys if I can scrape up a needle valve unit (complete) I will be in biz back cover plate gasket no issue I can make one martin
find a drop in
JUst checked to see if we could drop in an ASP 12 carb , no good diameter too large , the the drone has a threaded venturi and crankcase to accept it, not an issue if we could find a drop in to pass the threads
it would seal with an O ring and the side could be tapped for a small screw to secure it martin

If you can locate them, the old Austin Craft needle valve assemblies look the most authentic as I think they bought many units from them too. They made jillions of those things and they pop up on the auction sides pretty often.
But you can use many other needle valve assemblies just fine too. OS, Enya, Fox or others for example.

Now then if you have some types of needle valve units and the center needle is missing, it is pretty easy to make one and solder it back into the needle holder cup. I found a piece of mild steel rod that fit into the needle spray bar and chucked it up on my drill press and used a file and some knife sharpening stone to shape a needle point and taper on it.

Here is where I did just that myself as I had received this engine without the needle, but I still had the needle holder.

well backplate issue solved used stretched an O ring over insert put on backplate great seal dumped the back attached tank will use external one-needle valve issue next martin

If I can find an original needle set to go rest of set up ok

may be a repeat NEEDLE ON THE WAY FROM FROM WOODY BARTLETT martin

Martin, Look in the box that contained the the last engine sent. I believe their was sandwich bag that contained the needle valve for that engine.

Chris

Chris yes the needle valve was in the bag issue it has the threaded brass piece it screws into brpken off flush with end of needle holder cannot get it out martin
new one in the way so no issue martin

Martin, let me know when you get it that Drone running.  When the weather warms up a bit I will go back to sorting old tools and spare Model A Parts and may come across more plane stuff.  I'll also take my 12 year old grandson out to my son's place and teach him how to shoot that old Remington single shot 22. that we both used to kill rats at the dump, when we'were kids.
     
Chris 

Chris got the needle in ,mail today perfect fit in threaded holder martin

Well after some piston and liner swapping finally came up with a combo got got us some fair compression also installed a PAW c/l needle assembly in the Drone venturi
put on a 13x5 XOAR prop primed hand flipped , ran for a few seconds off the prime Davis ABC mix will hook up the tank Fri or Sat and go for a run curious what the RPMs will be on this prop, the original tank is not mounted just the insert back and with the backplate, clamp gasket was shot so used a nitrile O ring seems fine martin