What's the attraction of diesel plane engines?
04-28-2018, 05:24 PM
#26
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Ringed engines should NEVER EVER be used as Diesel conversions in the air. IMVHAIO. Ringless pistons are the proper way to go as is the proper fuel. Synthetic oils have NO place in model diesel fuels. Set the engine right and you shouldn’t have to do much to it for a long time. Carbon buildup in a short period of time causing the engine to not run properly leads me to believe either improper engine settings or incorrect fuels being used. IMO.
04-30-2018, 10:46 AM
#28
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Back in the 60's diesels up to .15 (or 2.5cc) rarely had problems other than to those who didn't like the smell. At the time we thought bigger engines like 3.5cc upwards would not be very suitable due to the vibrations that came with increased size. The really big engines that came to use later on, often with a piston ring, is yet another matter.
So for smaller CL engines, I think diesels are really good fun. No carbon problems that I know of. The combat and team race diesel powered models have shown us how powerful these little engines can be.
Maybe the diesel concept is best suited for the smaller engines?
So for smaller CL engines, I think diesels are really good fun. No carbon problems that I know of. The combat and team race diesel powered models have shown us how powerful these little engines can be.
Maybe the diesel concept is best suited for the smaller engines?
04-30-2018, 12:37 PM
#29
I spoke at length with Dave Platt about his diesel experience. He grew up flying diesels (mostly Oliver/Tiger) in Great Britain and it is my impression he is/was quite well-versed in them. Back when he was competing at the highest levels of RC Scale, he was campaigning a T-28 in which he had installed a Moki 1.8 2 stroke glow. However, he wanted to spin a large 3 blade prop and also to have the engine fully enclosed and was worried about over-heating a regular glow engine under these conditions... So he converted the big Moki to diesel. In our conversation he told me he could never get the engine to run well enough to use in this application; he tried different fuel mixes and carburetion and finally gave up, converting back to glow.
It seems some engines just make bad diesel engines.
My experience has been that you probably cannot go wrong with a P.A.W.
They may not be the most modern powerplant, but they are designed from the ground up as diesels, and have many years of successful diesel experience behind their construction.
Picking the correct type of model and flying style is also integral to "success" with a diesel.
It seems some engines just make bad diesel engines.
My experience has been that you probably cannot go wrong with a P.A.W.
They may not be the most modern powerplant, but they are designed from the ground up as diesels, and have many years of successful diesel experience behind their construction.
Picking the correct type of model and flying style is also integral to "success" with a diesel.
05-01-2018, 03:11 AM
#31
I used Davis conversions as well. I did not adjust the engines his way nor did I use his fuel. I mixed my own fuel and used tuning advice from a friend. I run my conversions slightly rich of peak and adjust the compression accordingly.
My fuel was 31% ether, 23% castor oil, 2% Amsoil cetane boost, balance JetA or Kerosene. Works every time without any poor habits or side effects. Davis fuel has synthetic oil in it which IMO is not a good choice to make. Model engine synthetics do not have the pressure properties that castor does and likely why more of the oil burned than blowing out the exhaust. IMO based on speculation and no pictures.
My fuel was 31% ether, 23% castor oil, 2% Amsoil cetane boost, balance JetA or Kerosene. Works every time without any poor habits or side effects. Davis fuel has synthetic oil in it which IMO is not a good choice to make. Model engine synthetics do not have the pressure properties that castor does and likely why more of the oil burned than blowing out the exhaust. IMO based on speculation and no pictures.
05-01-2018, 09:01 AM
#32
I used Davis conversions as well. I did not adjust the engines his way nor did I use his fuel. I mixed my own fuel and used tuning advice from a friend. I run my conversions slightly rich of peak and adjust the compression accordingly.
My fuel was 31% ether, 23% castor oil, 2% Amsoil cetane boost, balance JetA or Kerosene. Works every time without any poor habits or side effects. Davis fuel has synthetic oil in it which IMO is not a good choice to make. Model engine synthetics do not have the pressure properties that castor does and likely why more of the oil burned than blowing out the exhaust. IMO based on speculation and no pictures.
My fuel was 31% ether, 23% castor oil, 2% Amsoil cetane boost, balance JetA or Kerosene. Works every time without any poor habits or side effects. Davis fuel has synthetic oil in it which IMO is not a good choice to make. Model engine synthetics do not have the pressure properties that castor does and likely why more of the oil burned than blowing out the exhaust. IMO based on speculation and no pictures.
05-01-2018, 10:54 AM
#33
The best is to get ready-made fuel, rather than experimenting with different blends. What has worked well for 70 years will still work well....
Doesn't Davis Diesel Development provide fuel in the US for instance?
Doesn't Davis Diesel Development provide fuel in the US for instance?
05-01-2018, 11:02 AM
#34
FHS (Red Max) was another source - not any longer.
Aerodyne (British I think?) also not available.
Home brew seems to be the only option; ether and amyl nitrate are impossible to obtain in many places.
05-01-2018, 11:36 AM
#35
I use John Deere starting fluid and Amsoil Cetane Boost for my fuel and it works identically to Davis fuel as far as power and starting/handling goes. I do not have excessive carbon build-up either.
I mix my own diesel fuel because it’s about 60% cheaper to do so as well as the fuel has exactly what I want in it at the proportions I want. Davis fuel costs about $15 per quart plus shipping. My fuel costs me about $6-7 per quart to make myself.
I mix my own diesel fuel because it’s about 60% cheaper to do so as well as the fuel has exactly what I want in it at the proportions I want. Davis fuel costs about $15 per quart plus shipping. My fuel costs me about $6-7 per quart to make myself.
05-01-2018, 08:36 PM
#36
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A big 10 c.c. Russian Zeus and a big fan up front ... a Bolly Clubman 13.5 x 6. Old OS .25 FSR carb. Conversions are great if the base engine is built to take the extra strain and the conversion head is properly engineered.
Last edited by fiery; 05-01-2018 at 08:50 PM. Reason: Correct propeller specs.
05-01-2018, 08:46 PM
#37
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Ringed engines suck as a diesel? No-one told that to this nice Webra Speed .61.
Delay in starting was due to my not advancing compression. Once I did that it fired right up.
Delay in starting was due to my not advancing compression. Once I did that it fired right up.
05-02-2018, 01:45 AM
#38
I’ve run ringed Diesels too. They don’t hand start for beans, and seemed finnickier to adjust. The ringless engines seem 10X better and easier to handle, so I dumped the ringed ones or converted them to ABC. I recently converted a ringed ST .51 to ABC with a piston/liner from a Tiger Shark .52. I haven’t run it as a Diesel yet, but I intend to. My benchmark 7.5cc prop is an APC 13x6, which an ST GS.45 ABC can do around 10,800+. I’d think a 13.5x6 would be a little small for a .61?
05-05-2018, 03:47 PM
#40
It’s near 100% when you remove the propellant. It’s 80% ether and 20% propellant. I treat it as pure ether and my fuel matches Davis Diesels fuel in rpm from the same engine. I actually get more power in some cases.
05-05-2018, 05:08 PM
#42
My Feedback: (66)
I use John Deere starting fluid and Amsoil Cetane Boost for my fuel and it works identically to Davis fuel as far as power and starting/handling goes. I do not have excessive carbon build-up either.
I mix my own diesel fuel because it’s about 60% cheaper to do so as well as the fuel has exactly what I want in it at the proportions I want. Davis fuel costs about $15 per quart plus shipping. My fuel costs me about $6-7 per quart to make myself.
I mix my own diesel fuel because it’s about 60% cheaper to do so as well as the fuel has exactly what I want in it at the proportions I want. Davis fuel costs about $15 per quart plus shipping. My fuel costs me about $6-7 per quart to make myself.
Thanks
05-08-2018, 10:22 AM
#43
05-12-2018, 03:30 PM
#45
As long as it contains no additives. Check the label. Larger quantities is cheaper though. I get a gallon for $17+shipping. Usually around $22-25 shipped. Last time I bought an 8oz bottle it costed $5 at Wally world. For mixing large amounts of fuel, it’s impractical to use such small quantities.
05-13-2018, 11:55 AM
#46
My Feedback: (149)
Great thread and have certainly enjoyed reading this. Not a lot of experience here, but years ago have run a 40FP w//DDD on stand. After a long break, and having accumulated numerous DDD heads for mostly K & B engines, have a MVVS .61 and factory diesel head which I'm hoping to install in a J3 Cub. Maybe a 16" prop will be about right. Tried to check for DDD fuel at TH, but unable to access it. All Things change, don't they!
Thanks again
Thanks again
Last edited by triumphman49; 05-13-2018 at 11:56 AM. Reason: misspell
05-14-2018, 05:32 AM
#47
Great thread and have certainly enjoyed reading this. Not a lot of experience here, but years ago have run a 40FP w//DDD on stand. After a long break, and having accumulated numerous DDD heads for mostly K & B engines, have a MVVS .61 and factory diesel head which I'm hoping to install in a J3 Cub. Maybe a 16" prop will be about right. Tried to check for DDD fuel at TH, but unable to access it. All Things change, don't they!
Thanks again
Thanks again
