Model diesels - intentional low power uneven running

[Jon H]

Hi Robin, that is likely to be a bit tricky as the videos i make will be the engine being test run and with the camera a fair distance away so i dont kick it over or cover it in oil. It has a decent zoom and i have been able to get a tach in shot before.....

I will see what i can do. I usually do the initial run on a 14x7 and then move to a 16 or 17x6 and set it for that before shipping.

[Mike Etheridge 1]

All my early experience in the the late 1950's was with small diesels as I bought a DC Super Merlin when I was 12 and three of my school mates bought Mills 0.75's. I soon learnt when running in the Merlin that if it was over compressed then the revs would die and the engine stall. So to get the engine to run out the small integral tank it was necessary to reduce the compression and listen for the ''burp burp burp' sound. It took a long while to run-in the Merlin but not so long the Mills engines. One of my friends eventually bought the ED Racer I still have, and at the time we viewed the motor as massive in size. Over the years I have owned PAW motors of various sizes, and my nephew who I passed on my diesel knowledge won a 1/2 A combat competition with PAW 'Blue Head' motors and mixed with the top combat guys at the Nationals and competed with the very powerful Russian diesels.

[Doug Campbell]

In response to Ken Andersons post that not many engines available There are plenty of diesel engines on the market if you know where to look. PAW have a huge range, Oliver Cubs, Tiger, and Major, Redfin are some of the domestic suppliers. There is a good variety of Russian engines along with Parra
And don't forget Laser four stroke diesels if you can get one. They are spending too much time on this forum and not getting my 80 diesel built. We have never had it so good.

Edited By Doug Campbell on 29/01/2016 19:07:25

[Alan Gorham_]

Enya also make a range of diesel 2 and 4 strokes. The 4 strokes don't have an adjustable compression lever.

[Jon H]

Im working on it Doug! In fact I might have it finished next week now I have the crankshaft

And the enya diesels are quite interesting and run well considering they have no com screw. Our do have a comp screw though and are not quite as spendy.

[PatMc]

Here's the list of UK engines in production & for sale in 1965.

 

The vast majority are unthrottled diesels. Only one diesel is over 3.5cc - the Taplin Twin which TBH was more suited to powering a model boat or model road roller than a model aeroplane.

There were also a number of diesels from other countries available in the UK in 1967 - including from German, Italian, Japan, Czechoslovakia, Norway, Hungary, Australia & possibly elsewhere.

Edited By PatMc on 30/01/2016 20:59:43

[IanN]

Posted by Keith Evans 3 on 27/01/2016 17:23:16:

Thanks for your help with landing scenario .

Yup when I flew my control line K.K . Firebird at the field a few years ago fitted with a PAW 19 only one other guy new how to start a diesel .And I had to tutor my hand launcher in the letting go procedure with all the necessary arm raised and lowered business .I hadn't flown C/L for 30 plus years and wished I had moved the C of G a bit more forwards and only half filled the tank .!!!!

I've still got it along with a "Rascal" ,Bluepants ,and the Hall Racer and Gee Bee out of the Eagle Book of Model Aircraft .

Must try them again sometime .

I built a Blue Pants back in the day

**LINK**

It was powered by a second hand A.M. 35, Pretty much all the hardware was "home brewed" tank soldered up from tinplate, bellcrank cut from paxolin, elevator horn shaped and bent from a piece of alloy. The latter proved to be a mistake - the piano wire pushrod eventually wore (and no doubt vibrated) the hole in the soft metal horn so large that it failed and opened out. Instant crash. It repaired well enough though and flew again

[Jon H]

most diesels I have flown have been unthrottled or had a throttle that was next to useless. The Laser diesels throttle surprisingly well. In fact I put together a Laser 70 diesel on Thursday, runs really nicely in fact. If anyone wants one I can build you one. Currently it is super rare with only one example in existence

[brokenenglish]

Jon, I've been a Laser fan for 30 years and I possess several, including an early diesel,

BUT my PAW 19, 40 and 49 and Taplin Twins start first flick and the throttling is superb.

[Jon H]

I have a PAW 149 and 249 and the throttles on them are not that good. The PAW 60 I have has a better throttle but I have only ever bench run it and the settings are not yet perfect

[IanN]

Yes, I agree that the throttles on the smaller PAWs aren't what a lot of people might expect. My 149 and 249 don't deliver anything like the same degree of fine adjustment, especially at the lower end, than you would get from an equivalent glow. That said, they are perfectly usable and good enough for my meagre flying abilities. My 19s were fine, and the 29 and 35 both good though the latter two are bench run only

[PatMc]

My PAW 19 wouldn't run consistently at lower throttle settings, it always richened up, needed full throttle held for a few seconds to clear it. Even then it often ran as if under compressed for a further few secs before picking up the it could be closed down to low throttle again. At the Nats one year I spoke to someone at the PAW stand & was advised to increase the non-adjustable airbleed hole on the carb to a specific size (IIRC he actually gave me the right size drill). This did improve throttle control to an acceptable degree.
However soon after this I was given a couple of old type, OS cloned Thunder Tiger 20 guttless wonders. I fettled the carb from one to fit the PAW 19 & it improved the throttle control no end.
The other TT throttle and a PAW silencer were fitted to a, previously unthrottled, Yin Yan Silver Swallow 2.5cc diesel which also proved very successful.

[GONZO]

Enya 09 RC carb(variable air bleed) fits the PAW 1.49, 15 and 19. The choke size can be varied by moving the main jet position from the centre for the 149 out towards the edge for the 19, although you will loose sucktion. The ASP21 two needle carb fits(with very light dressing down of the carb spigot) the PAW 29 and 35. ASP21 carb from HK

HTH

Edited By GONZO on 31/01/2016 15:47:11

[Doug Campbell]

I have carried out the Enya and Asp carb mods with very good results. The smaller PAW do throttle very well as long as there is a reasonable ether content in the fuel. They are quite critical on this.