earlwb

Now since all that sitting around doing nothing all these years at caused the ball bearing to go bad, I took the engine apart to clean and study. After measuring the ball bearing, it appears it is a R6001 type of bearing with 12x28x8 millimeter dimensions. I think I have some at home from other projects, so I'll be tearing apart the house looking for them. Anyway that sort of explains the odd size measurements I was getting using inch measuring of approximately .0469 inches, 1.1020 inches, and .3155 inches. I found it fascinating that way back in 1948 that someone may have used a metric sized bearing in a Made in the USA engine.

I found it interesting in that they did not use a bronze bushing in the front of the crankcase. They left it as aluminum and used the ball bearing in the back to handle all the load stresses from the crankshaft. The connecting rod is also not as heavy nor as robust looking as the earlier bushed engines either.

I also found it interesting in that the cylinder sleeve does not have a lip on it. Instead they bored the crankcase to have a step or shoulder at the bottom for the cylinder sleeve to butt up against.

earlwb

I also made a couple of RC carb adapters for the earlier bushed crankshaft model engines that have a removable intake venturi. The intake venturi I pulled off of one engine was threaded as a 5/16x32 thread. So I made the first adapter for that. That turns out to have bee a big mistake as actually the engine was threaded as a 5/16x24 thread instead. Apparently someone had made a custom larger big bore intake venturi and threaded it wrong. The big bore venturi would still work, but it only threads in a turn and a half maybe. But maybe way back then there was a reason for it, I don't know now.
Anyway, I then made a second carb adapter with 5/16x24 threads and it fit just right, like you would expect.

I also found that the ThunderTiger GP .15 carb does barely fit as the muffler just barely clears the main needle valve unit. But I can use a short length of piano wire as a extension to solve that problem of being able to adjust it. I also found that the Thundertiger Gp15 and Gp10 carbs appear to be the same, so I am not sure if a GP10 carb would do anything different over the GP15 carb.

Anyway, I'll be test running the engine with the RC carb adapter later.

[email protected]

earlwb, correct the Drone II uses a 12x28x8 metric unshielded ball bearing. I obtained 3 of these ball bearings from Boca Bearing at the Toledo R/C Trade show a few years back. Three of my four Drone II now have new ball bearings. Jack

fiery

My Feedback: (2)

Nice work

earlwb

Thanks, it will be interesting to see how well the engine works with a throttle on it.
it isn't like it has a large RPM range when it usually doesn't rev much over 6,000 RPMs.

earlwb

I had a interesting thought about the Drone engines. Both the bushed and ball bearing versions use a full round crankweb on the crankshaft. No balancing was done to them to help cut down on vibrations. Usually the designer has cutouts or reliefs cut into the crankshaft web to help balance out the piston and rod in the engine. But they didn't do that on the Drone engines. Anyway I found that interesting. It might be that at the lower RPMs the engines run at that the vibration levels would not be a issue per se.

I was putting together the engine to get ready to test run it, when I found that the muffler fits OK or the carb fits OK but there just isn't quite enough clearance for both to fit OK. So I'll need to make a muffler extension to get the muffler farther out to get it ll together OK. The muffler straps and or the screws holding it on get in the way. So more to come as I work it all out.

earlwb

The RC carb conversion on my old Drone .29 engine worked a lot better than I expected it to. But with the muffler on it, it is acting like maybe it is a little over compressed with the Master Airscrew 13x6 prop. So I'll try a 12x8 prop again later when I go to use the engine in my old Sig Senior Kadet plane. The ideal prop is likely between the 12x8 and 13x6. But without a muffler on it, the engine acted a little under compressed but with the wide 13x6 it acts a little over compressed. But it did run pretty good with the 13x6 though, so it is really close. Putting a RC carb on the engine works well, but the RPM range is sorta narrow, from around 2,200 to 2,400 RPMs up to around 6,200 RPMs or so. Anyway maybe a narrower 13x6 might be the way to go, or a APC 13x6 or something. But then a 12x8 offers the potential for a little more airspeed too. A hint for the over compression is the black color fuel residue coming out. of course I was running it on the rich side a little too much too. Now then the muffler was canted up ever so slightly by the test stand mount screw underneat it. So there might be dark oil residue due to the muffler not fitting on as tight as it should. Also fuel tended to leak out around the muffler pressure fitting too. The exhaust out of the muffler looked sort of clear with a little tan color to it, so the dark stuff just might be off the test stand and muffler mostly.

In hindsight a OS carb or some other carb with a straight out needle valve unit might make for a better carb to use on the engine. But I got a good deal on some Thunder Tiger GP carbs, so I was bound and determined to get it to fit with the muffler. I used a short length of piano wire to extend the needle valve out just past the muffler so I can tweak the needle valve.

Now the engine was amazingly quiet with the Fox .15 muffler on it. I was somewhat pleasantly surprised by that. So that was pretty neat actually.

I'll cut off the excess length of the clamping strap later when I mount the engine on the plane.












Of course here is a boring video clip of me fiddling with the engine some, checking out the throttle response, etc.

[youtube]http://www.youtube.com/watch?v=YoQAEKX64Og[/youtube]

Recycled Flyer

Hi Earl,
there was an old school of thought that considered the 'paddling' effect of any internal moving part of the engine, the conrod can be seen to be the most obvious 'paddle' and indeed modern Go Kart engines have knife edge rods to try and minimise the 'paddling' effect or internal drag.

Now the crank counter wieght is another source of 'paddling' and made much worse if balancing cut outs are used, so older designs considered them to be of detriment to ultimate performance - my have times changed. (There is an article on this in the 'Model Engine Development' section over at http://modelenginenews.org/)

Now obviously the Drone is not a high performance job that would need to consider any paddling effects and the lack of machine work on the crank web would have undoubtably been done due to cost cutting but the above train of thought just may have been considered also.

Cheers.

earlwb

I remember that. I have seen some designers put in streamlined rods and streamlined crankshafts where the balancing cutouts are. The current custom performance aftermarket crankshafts for the Rossi engines is a good example for that. Apparently on the Rossi's streamlining the rod didn't seem to gain anything though. it might be the small model engines don't benefit from that as much as a large engine might.
You can see where they angled the cutouts on this Rossi rod for a purpose like that to reduce turbulence etc.

[email protected]

Earlwb, very nice looking Drone BB you have. I have 4 of these engines. Two with serial numbers 11XXX are stronger. Two with serial numbers 13XXX do not turn up as high as the other two. The two 11XXX have exhast duration of about 120 degrees. The 13XXX one 100 degrees and the other 115 dgrees. I have run these engines with the stock fixed compression heads. But much nicer with the Aerodyne variable compression head. The best with APC 13/7 sport prop 6,900 to 7,000 RPM. Next with same prop 6,300 to 6,400 RPM. Both with serial numbers 11XXX. Serial numbers 13XXX best 6,000 to 6,100 and weakest 5,700 to 5,800. Jack

AMB

EARLWB fantastic effort to bring back a piece of history, and not a shelf sitter, my first engine was the drone 29 as a teenager, sadley the 50+ years since then and many moves it is lost
Your skills in this project a great kick-off to bring in 2012
In a long e mail to my high school flying bud Chris Oehler in Raleigh NC he has his, along with a couple of ignition engines from that era and looks like he may
get back into it (with the Drone) martin

ddd

For those of you that are thinking of building a Drone II, we sell the castings on ebay. As for the lack of balance it was not deemed necessary at the time also the bearings used in the Drone were New Departure bike bearings.

AMB

Mr Davis never ceases to amaze me, goes into " his magic black box" and comes up with Drone castings, when I got back into this years ago, went to the local hobby shop and there was an Irvine 40 diesel, my first engine since the drone, ordered some Davis fuel and off I went, I have still the the plane a VMAR apache ll ( still airworthy) and up graded with an Irvine 53 Davis head, recently for more punch

Looking back then came more Irvine 53s converted with Davis head and a variety of engines .10 to 90 that Davis made heads for he once told me
"you do not have a clue how to set up a glow engine" (hope he was joking), of course now more factory issue diesels irvine 20 MVVS 15s MVVS 40and 61 ( have davis heads) again.yes a few glows all 4 strk Saitos, ASPs, and a few classic type diesels PAWs

Bob Davis Happy new year, and thx for your great products and advice over the years martin

earlwb

Thanks Mr Davis for the Drone castings.
I plan on making one out of my castings. But I have been trying to decide on the best way I can manage to drill the three through holes for bolting on the front end. It isn't easy to drill a straight hole that long or deep. I think that originally the engine company probably spun the drill bit and also spun the crankcase too as well as feeding it into the drill bit. I can see some serious jigs being made to do it that way. But then maybe they just fed the crankcase into the drill bit without spinning the crankcase too. I think I have to practice drilling a few deep holes to get a feel for it. I had thought about just drilling the holes deep enough to thread and use shorter screws than screws that go all the way through though. But it doesn't look like there would be a lot of material where the holes are to drill and tap. But maybe there is, if I go with say 4-40 screws.

AMB

Earlwb First I am not a machinist, but the front casting appears to have a ring that goes into the crankcase casting to center it up. I am using my Irvine 40 diesel
as an example since it bolts on with screws in the tapped holes of the crankcase. on the drone casting the 2 top holes at the top by the motor mpunts appear to have a lot of metal around them, the lower one does not, however your idea of 4/40s say 1/2 inch long may work fine again just a thought, The again Leon Schulman elected to through bolt a bit more work but much stiffer attachment ?? martin
maybe top 2 tap and thread bottom thru bolt??


Post note I just took a look at the Irvine 40 crankcase and there is large bumps protruding cast in on the side at the screw mount locations hence beefy the drone does not

earlwb

I wound up acquiring a adjustable head and also a glow plug head for  Drone diesel engines.
Here are some pics of them.
What is odd is the unusual combustion chamber shape for the glow plug head. I would think a more standard squish band shape would have been much better.

Stuntguy13

Earlwb,

There are several articles on running the Drone with the original fixed compression. The trick is to use the Drone fuel mix 75/25 either/mineral oil. At one time when the Drones was King in control line they had a factory team. These guys would fly two at once as well as all the stunts of the day. The trick to being able to fly two at once was in the run characteristics of the Drone. If you read some of the articles or the original engine instructions it indicates that the Drone is adjusted differently than most diesels. For the Drone on Drone fuel mix you were suppost to start the engine and rich it slowly and once it was fully warm richen it until it quite, then close the needle 1/8 to 1/4 turn and fly. The trick they used to fly two at once was to overlean the faster of the ships a little. If it got to close to the second lead ship they would climb the ship which lean the engine and slowed the rpm and the ship got back in position.

Try runnning one on the Drone mix and let us know how it runs, it should start easyer and have less missing. The other trick is to match the load to the rpm and the conditions. With the Drone mix it has a very wide fuel/air ration almost as wide as glow fuel, this is what made the whole thing work so easy for them back in the day. The props they used were 11x10 oak wood with 1/4" thick blades or 12x8 again heavy, thick blades. This seemed to be the right load to keep the engine at around 6500 rpm and give the speed they needed to fly stunt.

I don't know who can provide a Drone fuel mix, best I have been able to do is John Deer starter fluid (80% either) and staight weight motor oil.

Best, DennisT

123Cat

About Starter Fluid

Ive run 30% Castor

and 30% Start Ya ******* - Starter fluid )( 20% ether content )


and 30% Kero


and it worked in a pre heated engine , by the way Im now pouring hot water over the cyl , it

avoids the fire hazard of a naked flame heat up


I was surprised it worked


It got my plane just high enough to smash it to pieces

Recycled Flyer

So ............. what is the missing 10%?

123Cat

30 + 30+30 =100



It was a Texta mark on the bottom of a 100Ml jar about 1/4 inch up from the bottom , metric measurement of course


, I dont do imperial measurement

earlwb

Do you really mean 1/3 + 1/3 + 1/3 of each item in the fuel?

The Drone engines I have all work quite fine with Davis DieselDevelopment fuel and a little extra castor oil added too.
Granted one has to match the prop to the engine with the fixed compression head.
But I sorta like the simplicity of it all, the "KISS" principle at work.

You are correct in that the engines were designed to run 75% ether and 25% mineral oil for the fuel though. Unfortunately it is very difficult to get the ether needed to make the fuel nowadays. You have to use mineral oil and not castor oil as the mineral oil gets burned partially in the fuel too and it moderates the combustion effects of the ether.

Stuntguy13

Earlwb,
I have been really fasinated with the Drone engine since I was 14. My first experience with the Drone was after hearing stories from my uncle of how it broke his finger (with a Drone 11x10 warclub prop) and just being drawn to the way it looked. I built a ship for it and mounted the Drone after having repaired a small chip in the front case housing with plastic aluminum and installed a K&B needle valve. Not knowing anything about diesel I simply opened the needle 4 turns fill the tank with OK Cub Diesel fuel, gave it a small prime in the exhaust, one choke and then flipped it with all my might. Boom - it was running set prefect, no vibration or missing. I'm then thinking - this is the greatess enigine we have! Next day I went to fly it with my friend, now the weather changed and at the field I got all ready, fueled up and started cranking and cranking and cranking.........well finally it must have gotten enough heat in the head it kept going. Not knowing that I should have richened the needle to smooth it out, I leaned it and it just kept missing, so we launched and just barely got into the air. At that point I thought this was now the worst engine we had and never flew it again until a couple of years ago when I was looking for something for Old Time Stunt. I now was able to research how to run it and I put it in a ship called the Guided Whistle. I have a VC head and some standard diesel fuel and with the VC head and the understanding of how a Drone runs I got going fine. It had lots of power and worked great until the compression screw started to back out and slowed down until I was on the mains doing just below take-off speed. Did about 6 laps that way until it finally slowed to a stop. Still want to get this to work. My biggest problem is still the residual smell of the burnt kero. I was thinking that if we used the John Deer SF and mixed direct from the can to a container with the needed oil per tank it would give fresh fuel each flight and without the kero there would be no residual smell, then people would hold my ship.

Best, DennisT

earlwb

Hey thanks for the copy of the Drone engine instructions on how to operate and run them.

Yeah I need to get some John Deere Starter fluid myself. But I have to drive like 50 miles to a John Deere dealer who has the stuff. In my locale, they don't sell it as the next door NAAPA auto parts store has their cheap stuff instead. So I haven't made it over there yet to get some of the good stuff yet. I think you may be correct on that being the way to get rid of the kerosene smell.

To think that way back in 1947 and 1948 a kid could go to the local pharmacy and the pharmacist could mix them up a batch of Drone diesel fuel while they waited. How things have changed. But that was before I was born though. So I never got to try it myself. But it would have been nice.

Stuntguy13

Earlwb,
I think that most starting fluids will work if they are fresh (i.e. not two years old like we get here in FL). The idea is to go from the SF can into a mix jar that has a specific amount of oil in it to make up one tank of fuel. Then use that fuel immediately to fly (or test run). Most of the SF that I can get has about 50% heptane some oil and the rest either. Doing some quick searches it seems that heptane is very close to kero in and is used as a standard test fuel for diesel testing. I have not had the time to test this approach but it seems if we use say a 3 oz test tank you could start with 3/4 oz of oil (I think 20 weight 2 cycle oil would be a good place to start, its cheap too) and just fill the other 2 1/4oz of SF should work. I think the mix jar could have an input tube that would go to the bottom and vent tube on the other side through the lid. I though that a modified spray top on the SF can could be fitted with a 3/32" tube that could connect to the jar input tube with some rubber tubing. Once the transfer is done you could remove the SF and connect the rubber tube to the run tank and use the vent to pressure feed the fuel. I did this with a regular fuel bulb just squeeze and let it fill. The question is does this type fuel with the heptane give enough power? Others have said if it were that simple why would they be using all the stuff in modern diesel fuel. My thought is that for a modern diesel it likely won't give the power that commercial fuel does, but in a Drone we are at much lower rpm and it might work just fine - after all lots of contests were won with Drone's running either and oil.

Best, DennisT

Stuntguy13

Guys,
Here is an interesting website that has a lot of information on the Drone and how it operates differently then more conventional diesels.

http://www.modelenginenews.org/ad/drone.html

Best, DennisT