I Love Diesels

Has anyone ever dieselized an LA .40 ?

How do diesels make out in stunt ships? The only one I've seen was a PAW .29 on a profile and, it looked like it was pulling through the manuvers pretty good.

Anyone care to comment on "Davis Diesel" conversion experiance?

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While I've used Davis heads almost since his first one in 1976 they still seem to evoke a gambit of emotions from everyone who has an opinion on the subject. That said I'll clarify my experiences by first saying that I've run probably 50 to 60 of his heads from .010 yes, there were 14 of them made, to a S.T 6000 twin, a Quadra 50 dieselized , Tartan Twins, most of the OS,ST, Irvine,Thunder Tigre, OPS,Rossi ,Fox, and some rather odd ones also. Most of my use has been in RC and relatively little in controlline.
There are no problems whatsoever with them in use for sport but for contest use a diesel can be a real experience. First flip starts require preperation far in excess of the normal glow and the consistancy of the run can vary. By that I mean that you could have too short a run or too long on the same amount of fuel on successive flights.
With that out of the way I've enjoyed mine a lot and they are effective, efficient, long lasting and will not cause excessive wear on a quality motor. Quality is the catchword as some of the imports aren't that good, even as a glow, and no conversion is going to make a silk purse out of a sows ear.
Advantages are broader torque range, larger props can be used, improved fuel econemy, lower decible noise from the motor, cooler running, the head is hot but the case should stay cool and certainly you can get fairly comfortable with the muffler in short order, adjustable timing to suit variable weather conditions.
Disadvantages are fuel stinks to high heaven, fuel can be as difficult to get off as heavily castorized fuel, glow fuel makes a great cleaner for diesel fuel though, everyone who gets in your car or truck for the next 2 years will know that you had something really awful in it. fuel can be expensive by the gallon but it does go about 2X as far per gallon.
You can indeed do a crankshaft or rod if you continuously run your motor overcompressed but in over 1K of flights in over 25 years I had it happen once and it was my fault.If you run overcompressed you will have the blackest exhaust that you can imagine and will wish that you had a share in a paper towel company.
Are they fun to run, you bet, are they the replacement for the modern 2 stroke,definitely not, but I've enjoyed mine.
They also have the benefit of usually being on a currently available motor, and parts and service are available at reasonable prices. Of course you could buy a conventional diesel ST 15D or an Oliver Tigre 15 If you have money to burn. The PAW's do give excellent service at very reasonable prices and their service is second to none.Be advised though that most of the vintage diesel manufacturers did not make motors over a .21 in size simply because of weight and vibration. PAWs above a 19 are also heavy for their size and can be vibrators.
Dennis
Dennis

I've flown Larry Renger's\AKA, "Designman's" diesel powered Magician and it was a blast to fly. That said, the run was inconsistant from flight to flight. But when it was on, it was great. The Europeans, the British in general, have a long history of diesel powered flying with RC and Controline. They seem to have a better grip in it then we do.

From another "stinky engine" guy,

I agree with just about everything Dennis said. Purpose-built diesels generally have heavier rods and bearings to cope with the harsher ignition impulse. Most of my diesels have been designed for this regime; MVVS, M-E, D-C, ST G15s and G20s, Webra and PAWs.

I haven't had much positive experience with the diesel conversions, and especially don't do this to a Cox; the piston/rod ball & socket won't take the pounding. After reading your post, I pulled the backplate off an LA40 and the rod may (just may) be strong enough to handle a conversion. I think you'd be happier with an OS FX or the older OS FSR conversion, if this is really what you want to do.

I believe you'd be still better advised to call Eric Clutton (in the PAMPA "yellow pages") and tell him what plane you want to fly and go with his recommendation on a PAW.

Regardless, good luck,

My diesel experience has been largely with purpose-built engines: ED Racer, ED Hunter, ST G20-15, Taipan, CS Oliver. My one, so far, conversion experience was with a Tower 40 and RJL head. The first problem I had was that the contrapiston in the RJL head came apart. It has an o-ring groove and on this one there was only about 1/32 metal below the O-ring. This shelf let go while the engine was running and the pieces of the shelf welded to the contrapiston and the top of the piston. The engine was running along and all of a sudden went way overcompressed and stopped. Gene Hempel made me a new contrapiston with a tchicker shelf and slightly different dimensions and I have had no problem with it. So far as we could tell, the only damage to the engine was that the rod was slightly twisted.

I actually have several Tower 40's and all but the most recent have been run diesel. I have gone through 4 cranks. The cranks have a grinding relief groove at the base of the shaft and that is where they break. I have been running a heavy hub and I think that may have contributed to the problem. However I have put several hundred flights on one of these engines glow with heavy hub and it is still flying.

So far as consistancy of run goes, I have not seen that as a great problem, although diesel fuel expands and contracts more than glow fuel with temperature changes. I basically adjust the needle to give me the run time I want out of the tank. I adjust the compression based on flight. If the airplane loads in maneuvers it is overcompressed. If it burps in level flight it is undercompressed. If it burps in maneuvers, it is a hair lean. With the Tower 40, when every thing was right, the engine would get warm and quit burping about the time I got to the handle and got ready for launch. I like to get things right and then leave alone, and start the engines at running setting rather than fooling with compression. I.e., use a starter if needs be.

I have a Magnum Pro40 with the RJL head on it that I'm going to give a try, without heavy hub. My Towers, and the Magnum, turn an APC 12 x 6 around 9,000 PRM.

Me too! I just couldn't resists. The crank should hold up on this engine.

http://www.bath.ac.uk/~ccsshb/12cyl/

Don't mess with the guy who flips it!

I'd like to see the lathe that was made on.

Tony Eifflaender, maker of PAW engines, has won our Nats. more than once with one of his 35/40 diesels. Despite this not many people follow his lead. Why not ask in the land of diesels? Check out the English Barton club's site, <www.controlline.org.uk/Barton/index.htm>. Ask questions on this forum, it caters for all c/l activities, you'll find an appropriate section to post your questions in.

I have a NIB PAW .40 TBR available for sale, at a fair price. Will throw in a set of Free Bird 40 plans. Send me a PM if you're interested. Steve

I have flown plenty of stunt with diesels, since Derek Pickard's articles came out in SN. I must say that I found that the PAW's are difficult to work with, because they are heavy and vibrate quite a lot. Some folks have more success with them. I have Tower .40 diesels, a Magnum XL .46, and plenty of MVVS .49 conversions. The MVVS .49 is the best, because it is a tough engine, and has a long stroke. I was hoping to do quite well with it in Muncie at the world champs, but my good model bust the outer wing right off in practise after just 5 flights. The outer aluminum wing joiner on the take-apart system failed in the rough air.

Before this the model was flying superbly. The diesel was set-up in just 3 test flights. I fly in Johannesburg South Africa, and our fields vary from 5000 to 6000 ft. ASL. My first flight was a bit fast, but totally flyable. The 2nd flight was a bit slow with lower compression and a bit richer setting. Flight no.3 was spot-on, and it was perfect. No head-shims, changing plugs, adding nitro...nothing but solid one-speed engine run. Pity the wing bust!

I used my back-up model for the rest of the competition, but could not get the glow .49 to behave in the strong wind. I then put the diesel head on the beast, but the model weighs 1950 grams, so it was a big ask. The cowl did not fit either, because the diesel head is a bit longer. I cut it out to fit, but then had problems with cooling. To cut a long lousy story short, I ran out of time, and the weather did not play ball. I did not hit the deck in the rough stuff in my second round of qualifying, but did not score either. The fact that the engine pulled such a heavy model through every maneuver, says a lot.

Back home, I have flown Saito 56 models and then my own .49 diesel directly afterwards. It has similar power to the 4-stroke, but is just so darm smooth that it feels like an electric motor. You get used to the smelly fuel eventually, but the performance and simplicity is hard to beat. I start my diesel quickly as well, and usually within 15 seconds from a cold start, I am out at the handle. This is not bad. In the winter, it takes about 10 seconds more. It's not a system for everyone, but I enjoy diesels. All the best.

Keith Renecle

The worthy ambition of every man, is to be half the man his dog thinks he is! (Lowery organ repair manual circa 1970)

Er....erm.......er.....thanks, but ...er.....I think I'd better get some of my own engines in the air first!

I,ve heard one of the biggest complaints is "you need a seperate
trailer to carry your plane in because of the lasting smell"
Other problems are cranks and rods breaking.
Course your stunt eng. will do the same thing if you modify it enough.
I have absolutly no problems with my power stroke diesel ford 250.
The block is steel and absolutly guaranteed for 100,000 miles
Its a purpose built eng. all for only several grand more money.
If I could get enough plywood, I bet it would work great in a free
flight.

Charlie, I guess as beauty is in the eye of the beholder, so smell is in the nose of the sniffer! When you've grown up on diesels, there is nothing unattractive about it. Trust me, the smell is quite pleasant. (Even addictive? I can't quite remember!). Glow on the other hand is not nearly so evocative.
No properly designed diesel will be more prone to break anything than a glow motor. Diesels are subject to more of a shock loading than glows, so if you convert a glow which will not take these loads, you do run the risks of breakages. Coxes are inclined to do this, and special stronger aftermarket shafts are/were available from custom suppliers to overcome this.
Don't think I was knocking diesels in Post No.11, Tony's performance with his PAW's is excellent. It's just that for me, I prefer glows for stunt. However, one day at VSC I might yet appear with a diesel and surprise a few people with its performance.