I have a McCoy .09 Diesel and an OK Cub .049 Diesel engines, in addition to my MVVS and Enya made to be Diesel engines. I also have a few Diesel conversions. The Cub starts easier than the McCoy, but both run well. Of course, neither has a throttle, so I don't use them for R/C flying. I won't fly R/C without throttle control. Which brings me to why I began writing this article to begin with. Why aren't larger, throttle R/C Diesel engines more popular? It seems that the really devoted folks to model Diesels are the guy that love those miniscule unthrottled Diesels with weird names. Are you fellows all right?


Ed Cregger

I believe MVVS and PAW both currently make a 60 size Diesel.

Ed, you posted this question in the wrong forum. You're preaching to the choir. Ask the guys that don't run diesel why they choose not to.

Greg

Ed

A lot of modern diesels are produced for competitive work in former Soviet/Eastern bloc countries. Not surprisingly some have what we in the West may perceive as "weird" names (JAK, FORA, CYCLON, PARRA etc).

As for large engines:

1. They cost more to produce than equivalent glow engines.
2. Piston/liner seal is more critical than with glow engines.
3. Fuel costs more (most IC flyers don't know of the diesel's frugality of consumption) and commercial availability outside of the US is patchy.
4. There is a perception they are difficult to start and operate. Smooth linear throttling can be problematical on some engines.
5. In days of yore it was believed large diesels (over the 3.5 cc class) were unfriendly to use and vibrated a lot.
6. When peaked to max RPM's, brown to black goo generation, which some flyers recoil in horror at.

I am sure many others will chime in with thir views.

Large diesels are not popular because:<div>

1. fuel is $12-$14 a quart in the US plus shipping
2. conversion heads are over half the cost of the engine
3. none of the large hobby sites like Tower carry diesel engines or the heads
4. lack of advertising
5. gasoline engines are becoming smaller and cheaper
6. electric motors and batteries are cheap
7. smell
8. most hobby shops do not carry model diesel fuel in the US
9. oil mess

<div>But all in all the main reason is the fuel cost. I mean why would anyone want to buy or convert an engine to burn expensive fuel when they can get a DLE 20cc or that new NGH 9cc and burn regular unleaded? Even glow engines can be cheap to run if one can get methanol locally by the gallon and mix it with some castor. One can get a whole gallon of castor from FOX for $20. Methanol is only like $4.00 a gallon.</div></div><div></div><div>just my .02</div>

I agree with KeroPower
smell
most hobby shops do not carry model diesel fuel in the US
oil mess
But I think the biggest reason is "monkey see, monkey do", there's not many of us doing diesels. I'm in 2 clubs one club has 40 members the other 140, only one guy had ever seen a diesel run before I brought mine out. I think their time has past, but I love the little stinkers, there is nothing cooler than a tiny diesel.

Here is a K&B 1.00, a SuperTigre 2300 and ST 4500, they ain't little. Most of the engines discussed here wouldn't make pony motors for most of mine.

Thanks for commenting, everyone.

Like you, Hobbsy, I too have several large model Diesel conversion engines, of which the Super Tigree G2300 is one.

Whoever said that I was preaching to the choir was right. I do see mostly conversions in the "larger" sizes of engines (above 1.5 cc)..


Ed Cregger

Tuning the fuel mixture is annoying enough. I don't peak my engines out because of this, I find a setting that's lean enough to not over-cool them and give them good power and I leave it alone for six months. Tuning the fuel mix AND compression? Not on my planes!


OS glows are fire and forget. Set the carb in April and you won't have till touch it till October. If you have a winter downtime you won't have to touch that carb until the engine starts to wear a bit. Glow plugs are also pretty fire and forget, a well tuned engine will run for years on the same plug with no issues. I've only read of one diesel engine that is that fire-and-forget, and I've never seen any of them for sale anywhere. There's also fuel considerations, as has been mentioned already. I can buy 15% glow fuel for a reasonable price, but if I want to run diesel I have to brew my own or order it by the quart from Davis Diesel. Lastly, I demand a throttle, I won't fly anything that isn't throttled, and that pretty much means converting an existing engine. Such a conversion puts the engine far above my budget.


If there existed a .40 size diesel that I could set and forget for six months straight, idled well, throttled well, made good power, cost about the same as an OS 46AX, and could be fueled easily and conveniently, then yeah, I'd run a diesel. 'Till then I'll just sit back and enjoy them as a spectator, let someone else burn half a tank fiddling with the compression and all that, which is what I do now.

You can get a Fox .45 engine new or even used (if not terribly abused) for a good price (older ones tend to go fairly cheap on Ebay even new). Then get a head from DDD for it.
If you like OS engines the OS FP or LA series work well. DDD was selling a new OS 46LA diesel on Ebay, it might still be there too.
The larger diesel engines tend to be set and forget on the adjustments and much less finicky than the really small diesel engines.
My Fox .45 runs great as a diesel too. Plus I don't have to fiddle with the settings after it is dialed in. The needle is maybe a twice a year thing to tweak when the weather changes.

There is no need for fiddling.
For hand flipping it helps to alter the compression but once it is started you end up with the usual setting, same with the needle. It is only if you change the fuel type or prop that you need to find a new optimum setting, but that is the same as for glow. Except on glow you have to take the head off to change head shims.

I don't think that diesel engines are ideal for everyone, but they are great fun for people who enjoy combustion engines. There is no need to try and change that, unless you selling/producing engines, it is a hobby and people should use what ever they feel like using...

PAW produces many throttled models.

Here, here now...I represent that.

George

Enya make some very nice ones too.

Is it okey to like small throttled engines?

Looking at the engines that are still being manufactured I think they are all offered in RC versions, small or big. It is only that the older engines were intended for CL, which was the thing to fly at the time. Here are a few examples of RC engines that are currently manufactured and are both fairly small and RC:

MP Jet .061
PB .020
PAW .033, .049, .061, .09 , .15 etc.
Enya .11, .15, .25, 41 (4-stroke)
Parra .09 (soon), .15

They still have some MVVS .15's available for people too. The MVVS 10cc diesel is still available as well for those wanting a .60 engine size.
PAW still makes some bigger diesel engines too, such as the .29, .35, .40 and .60 engines.
Everytime a PAW .60 comes up on Ebay, here in the USA, it sets off a feeding frenzy of bidding, and usually goes for more than to just buy one direct from PAW.
So I think there is still interest here in the USA for big model diesel engines. There may be some locales that have a large number of modellers interested in diesels and using them, but I am not sure where though.

With Davis Diesel Development making conversion heads for many engines, one can convert a RC glow engine over at will. Plus you can convert a Supertigre G4500 over to diesel and it runs really well as a diesel too. Of course it has one wondering if they converted a Supertigre 60cc inline twin to diesel as to whether it would work good or not. It is two ST G3000's connected to make a twin.