Diesel v Glow

[Bob Cotsford]

PAW had a 60 diesel mounted in a test stand at one of the shows a year or two back, and they were inviting potential customers to start and operate it.  If I recall correctly it started 2nd flick for me, and throttled very nicely, but that was without a prolonged spell on tickover.

 

I went through a nostalgia spell and had a few modern PAW units, but they really didn't compare with glow motors for throttling, ease of starting, or outright power.

[Erfolg]

Steve

 

I suspect that you are probably 10 years younger than me, that is you are no more than 55, probably younger still.

 

Cos! when i waz a lad, fuel was sold in small cans, probably 1/4 pint and was made (or marketed) by Keil Kraft or Mercury. Gallons, would have been unbelievable quantity for young lads.

 

Going to the chemist to buy a pint of ether was no big deal, even saltpetre (other than around November). Amyl Nitrate and the other types of enhancers were not used by me or my mates, if I reember correctly.

 

I am not sure where you could buy paraffin now. Then it was so mainstream, that the B&W TV ran adverts for "My friends asked me how I knew, it was Esso Blue, I of course replied that with other brands one buys, smoke gets in your eyes". Of course there was Shell Pink?.

 

I do wonder why Diesels fell out of favour. I suspect that they were not as easy to start, for a 10 year old. The compression needed to be about right, the fuel set about right. Then when running you had to back of the compression screw, fine tune the fuel supply. Lads are generally not to disciplined to get this right.. Where as the small cox, was easy, clip the battery on, wind back against spring, let go, and away the motor sings. There was a wide variability on quality of build from some British Diesel manufactures. Where as OS, Enya, Fox and Cox, were bang on and attractively priced. With RC, throttling and predictable idling were seen and are a necessity.

 

Erfolg

[Steve Hargreaves - Moderator]

Erfolg, you are quite correct...being a mere 44 & 3/4 years old I am but a babe!!! I got my first engine, a DC wasp 0.049 glow in 1976 & the fuel came in 1/4 litre tins...KeilKraft Nitrex 15 it was. For diesels you could buy Model Technics D1000, D2000 & D3000 & even now, 34 years later, you still can!!!!

 

I can't think that 1/4 litre cans would be the right way to buy diesel fuel now though...especially for a 10cc or similar motor. Another point is that diesel always came in a metal tin because the plastic ones allowed the ether to evaporate!!!!

[Richard Wood]

Who was it made 'Quick start', 'Sport Special' & 'Racing Brew' diesel juice?

Might have been Davies-Charlton. Or were these Cox glo' fuels

I'm just a 46 1/2 year old nipper & got a DC Spitfire & a tin of fuel for my 14th.

Got the DC motor running just in time for my 15th.

 

Edited By Richard Wood on 10/03/2010 13:42:26

[Steve Hargreaves - Moderator]

It was Easy Start (D1000), Sport Special (D2000) & Racing Brew (D3000) as made by Model Technics & still available at your local hobby emporium...see here

 

Also for diesel newcomers some interesting dieselly stuff here....C/L actually but still interesting

[Myron Beaumont]

The word " Ethereal" comes to mind  

[Richard Wood]

Ah yes, thanks - Remember it now

 

[Matt Halton]

Posted by Ultymate on 09/03/2010 15:40:48:

Posted by Matt Halton on 09/03/2010 12:40:00:

Don't forget the AM .15 and .25, not as good as Ollies and PAW's but I found them very reliable easy starters.

 

How much are new build Oliver's now then?

 A new Mk 4 Oliver Tiger from what info I can glean sells for £185. There is a very special MK 5 being produced which there will only ever be 65 produced apparently which is priced around the £300 mark

 Wow! Thanks for that.I bought a good condition secondhand one when I was sixteen, and I had to save hard on my paper round for that,it was £18..wish I had kept it, £185-£300 new, crumbs..I felt like a king at 16 when I finally purchased that motor.

 

I flew C/L Combat that year at the Nats, built 2 Warlords,got knocked out in round one...my opponent cut the elevators off both models in no time...happy days!

[Romeo Whisky]

"What really matters" - to quote your thread title, is flying model aeroplanes. 

 

The power set up is of interest of course but there is no need to demean the up-to-date modern tear-aways who fly electric,(like me) or those who's joy is flying gliders with no power at all except except what the wind and the sun deliver for free. 

[Ultymate]

Posted by Romeo Whisky on 10/03/2010 16:08:05:

"What really matters" - to quote your thread title, is flying model aeroplanes. 

 

The power set up is of interest of course but there is no need to demean the up-to-date modern tear-aways who fly electric,(like me) or those who's joy is flying gliders with no power at all except except what the wind and the sun deliver for free. 

 The thread title is Diesel v Glow

[IanN]

Posted by Romeo Whisky on 10/03/2010 16:08:05:

"What really matters" - to quote your thread title, is flying model aeroplanes. 

 

The power set up is of interest of course but there is no need to demean the up-to-date modern tear-aways who fly electric,(like me) or those who's joy is flying gliders with no power at all except except what the wind and the sun deliver for free. 

 My thread title was tongue in cheek. No intention whatsoever to demean anyone, and I don't think that the many interesting posts have been at all anti either electric or glider. If you interpreted it differently, all I can say is sorry

[Peter Miller]

I don't think anyone has been demeaning electric here.

 

As far as I can see electric power is as different form i.c as gas turbines are and so just do not have aplace in this thread.

 

No one has mentioned spark ignition yet. IT won't be me, I have only run a couple of vintage ignition engines.

 

I did see a throttled spark engine at Old arden once. it had the throttle coupled to the advance and retartd and I have never seen smoother throttling. Magic.

[IanN]

This

 

might be of interest to people interested in diesel potential in modern applications

[Romeo Whisky]

IanN - I realised your thread title "dig" was tongue in cheek - and so was my response - hence the

 

Let's not get too sensitive here - one of the joys of the aeromodelling fraternity is the banter.  Model flying is about fun.  "Vive La Difference" as far as power source is concerned.

[thomas oliver 1]

Diesels with sub piston induction will not throttle.  I made a throttle for a Mills 1.3 and when I shut it nothing happened.  I blanked off one exhaust port and it  throttled beautifully.   Interestingly,  there was no apparent loss of power.   It flew a 48" span radio model loaded with heavy home made radio gear ( servos had 21 transistors and boards were so big they were fastened externally on the casing).   The Mills never stalled or skipped a beat in several years of use.  I still have it and compression is still very  good .  Pickup  was slower than gloplug however.

[IanN]

Posted by Romeo Whisky on 10/03/2010 23:15:32:

IanN - I realised your thread title "dig" was tongue in cheek - and so was my response - hence the

 

Let's not get too sensitive here - one of the joys of the aeromodelling fraternity is the banter.  Model flying is about fun.  "Vive La Difference" as far as power source is concerned.

 

Absolutely no "dig" at all on my part, and its been a very long time since my diesel fuel addled brain  has been too sensitive.

 

Just popping down to the shed to sniff some more ether 

[Simon Chaddock]

I can confirm a Mills 1.3 throttles well with an exhaust baffle.

I ran mine on a bench with a long exhaust pipe that had a butterfly valve on the end.

I guess it got down to about 2000 rpm and it was so quiet you could hear the prop.

[IanN]

The ability to silence diesels is a a major benefit.

 

Whilst glows will throw a hissy fit if you increase the back pressure, you can put as many silencing devices as you like in a diesels exhaust with minimal impact on performance.

 

I've seen diesel models with two diffusers in series which were so quiet I thought they were electric

Edited By IanN on 11/03/2010 00:01:03

Edited By IanN on 11/03/2010 00:02:57

[Erfolg]

There seems to be a contradiction in a couple of statements.

 

I read and appreciated the statement of Diesels with sub piston induction, did not respond well to a carburetor in the induction tract. My first thought was why sub piston induction, I concluded that fluid flow(air) would have less losses this way. Which means that reducing the fuel air (in) by induction tract, means that the amount of air going into the motor remains proportionally little changed, whatever the fuel flow through the carburetor. For me so far so good.

 

I then read that if you choke the exhaust gasses, this allows throttling. Seems reasonable, in that it is limiting the air mixture in, probably pretty well proportionally, which ever means it enters the engine, dependant on gas flow out. Yep it is working for me, seems reasonable.

 

What then surprised me that diesels were pretty much independent of back pressure, which does not seem at first sight to sit that well with the outlet throttle/baffle. Suggesting that diesel would be pretty much insensitive to this form of control. Or is it that the outlet baffle has to be pretty extreme in restricting fluid flow (exhaust gases).

 

Puzzled

 

Erfolg

[Doug Ireland]

All way over my head Erfolg. I don't remember ever seeing a diesel engine with a silencer fitted, certainly didn't have any on mine!

[Erfolg]

If I had not been in a rush to collect my Lola Doll, I should have suggested in the first paragraph, that I would have expected the fuel air ratio for sub piston induction to "Lean Out" the mixture to the combustion chamber as the carburetter was closed. As a substantial part of the air is entering the piston, is unregulated, other than timing and by port size, via the sub piston induction.

 

Doug I am very sure you do know. As a kid we slowly lost our sites, as we did not know what a silencer was either. Our only attempts at silencing, were venturi devices, which sounded the same, but we fervently believed that they were now faster. Aren'T adults so unreasonable.

 

Erfolg

[Myron Beaumont]

Erfolg

Just a point -They're not diesels at all -They are combustion ignition devices actually !

Maybe a servo driven connection to the normal T-bar screw on the top could be used to alter the compression ratio in flight & the rpm  ie wind it back to reduce revs ? I appreciate the problems but its a better idea than our friend on the other thread  re; Charging batteries from an ic powered A/C 

[mal brewer]

  Myron, as far as I know, they are actually compression ignition devices !...........Mal.

[Myron Beaumont]

Mal

You're right .I wasn't happy with what I'd written somehow ---Thanks. It's a long time ago-------------    

[Brian Parker]

In reality a British Invention, Patent No 7146 (The Compression Ignition Oil Engine) taken out by the British engineer Herbert Ackroyd-Stuart in 1890, a full two years before Dr Diesel’s coal dust fuelled engine.
By the way, as I understand it, a sub-induction piston engine is optimised to produce performance at high RPM (at the expense of poor low-end performance) and it is not designed to be throttled.
Not tried it IanN, but not sure you can actually fit as many silencing devices as you like with minimal impact on performance.