G'day Hobbsy. Thanks for that. As I suspected, the good old cheap OS 46 seems to be a good all round candidate for a general purpose engine. I think that at some stage I will get one and have a play.

I have just ordered a reproduction 1958 Taipan 15 (2.5cc) from David Owen. I am pretty sure these were the engines in the shop window way back when that got me started in the world of model aircraft and their wonderful engines.

This is way off the topic but should interest an engine person - I have been asked to take a model engine and plane into the local ABC (public broadcasting) radio station this morning and start it so they can record it for a story about our club which just hosted a huge (by our standards) Large Scale Aerobatics competition. I am going to take a Saito 30 which is in a small Tiger Moth ARF. Should be interesting. It is quite a quiet engine but I hope they like castor oil. The plane and its little engine are also exactly the opposite of the monsters they were flying on the weekend. Most were in the 100 to 200cc range and petrol (gas) of course. Big $$$$. Makes my little Tiger Moth look positively insignificant but I like it. And it will fit in the car in one piece.

You ought to take a diesel with you also, nothing like blurp-bangarang-blurp-purr of them when starting up

G'day Patxipt. I should have been more specific in what I wrote to Dave. I am looking for a glow engine to convert to diesel and the LA 46 seems to be a good candidate. Also, the 1958 Taipan 15 is also a diesel. Gordon Burford and his son Peter manufactured engines in Australia from the early 1950s to the late 1970s. They made some excellent diesels and glows and the 1958 is held to be one of the best plain bearing diesels. The Old Timer croud here run an event called Burford which requires the use of a Burford engine and these are becoming rarer. I guess that Dave Owen's reproduction will be able to be used in these competitions as well as vintage control line events. Peter Burford makes an excellent 0.33cc diesel as well.

No, no, I was refering to the radio show you mentioned

Opps - sorry - totally misread that one. The radio show was fun. I took my little Saito 30 in its Tiger Moth but I did not end up starting it. They did not like the idea of oil spraying all round the place. We had fun telling the world what we do and the interviewer seemed interested. I hope they put it on their website so I can hear how dumb I sound.

And yes, my old Super Tigre G2015D would have sounded great in the studio. It is always at its best when just slightly undercompressed so that it misses the odd beat every now and then. It really amuses the glow fraternity who are not used to hearing engines miss. That is one thing about diesels, if you get them going, they rarely stop until the fuel runs out even if they are rich, lean or undercompressed. They may go "hard" or over cool or even splutter a lot but they rarely stop.

Your tiger is a ring engine and as such requires a break of at least one hour and a half, also a 12 X 6 is too big for a 51 an 11X 6 is correct. On break-in it is better to use a lower load prop. say a 11 X 5 running rich. The prior comments are based on glow operation. Your 51 is timed to run at least 12,500 Rpm.

Bob Davis
Davis Diesel

Diesel Friends, I put another hour on the Fox .50 today, it takes that long to a little over half of a 16OZ tank. At the end of the 60 minute run it is turning the Graupner 12x7 at 9,650, this time I used a stock EZ Just carb and stock Fox muffler. I can tell its improved in another way, it now holds compression like an ABC engine, no leak off when slow flipping.

I tried a different prop on the Fox .50 today, a Bolly 13.5x6, to my surprise the .50 turned at a 9,700.

Oh yes, the pipe, it is a Mac's .90 sized Quiet tuned pipe, it does not effect the rpm one rpm. At idle all you hear is swish of the prop @ 1,800 rpm.

David,


This RPM on that prop are a real 1.17 HP...

The 9,650 RPM you saw on the Graupner 12x7 are an even 1 HP...


A gain of 17% in power output does not usually happen, as you increase RPM by a bit over 0.5%... especially when it is running on what is not a tuned exhaust system!


Would you be willing to try both props again; maybe also on the other .50'ish Diesels?


It seems to me Pé's prop constant of 1.45 for the Graupner is significantly lower than it really is, (or that of the Bolly is too high...).

Thanks Dar, I will do that and I may order a couple of 12.5x8s from you, I thought I already had a couple of them but no find. I think the 13.5x8 I have would be too much.

David,


I still have a small stock of the Bolly Clubmans, although the model products branch of the company has been liquidated.

Many more are of larger wood sizes... I will E-mail a list to you.


I await your results with the two sizes you had mentioned here.

I re-ran the Irvine .53 today with a Bolly 12.5x8, in the first post in this thread it had turned the Graupner 12x7 at 10,121 rpm, it turned the 12.5x8 9,150. I also ran the Irvine .25 with a Graupner 10.5x6 with an AJCoholic head and Davis InCowl Quiet Muffler as pictured and it turned 8,850. Its wearing a Bolly in the picture but I ran a Graupner today.

David,


Welcome back to moderation!

Can you check how well your AJC head MVVS .49, does on the 12.5x8 Bolly Clubman?


I remember it getting over 10,300 RPM on the 12.5x6...

He left? <G>


Ed Cregger

are these diesel engines??

my god......intresting!!!

These are .50 size Diesel conversions, I have quite a collection of them. My 42 year old daughter had a stroke in mid May so our life has been comsumed with her care and her 5 year old son. She has made great progress through shear guts, will and determination. Life is getting back to normal. Sorry for my absence here. I'll play catch up.

I hope all goes well for her recovery Dave. Cheers.

Thanks Derrick for the kind words and for the kind words recieved in PMs. Lynda has full use of her left arm now, she can now hold her head straight up and her left leg has come a long way, its just a little draggy now. Many prayers and support from litterally hundreds of friends have really made a difference. Thanks all

Good Luck Hobbsy!
Peace be with you.
Rob

Moved up for CW

Hi Hobbsy,<!StartFragment><p class="MsoNormal"><o></o></p><p class="MsoNormal">(As you know, I love this topic.)<o></o></p><p class="MsoNormal"><o></o></p><p class="MsoNormal">If you had to choose one of your diesels to be installed into an aircraft that had to (say) tow a flag or banner at an even slow speed, which one would be your pick?<o></o></p><p class="MsoNormal"><o></o></p><p class="MsoNormal">In other words, which one would lug around the best with a heavy load attached to it?<o></o></p><p class="MsoNormal"><o></o></p><p class="MsoNormal">And how might you select the pitch of the prop for this kind of work?<o></o></p><p class="MsoNormal"><o></o></p><p class="MsoNormal">Cheers.<o></o></p><!EndFragment>

Are we talking about a TeleMaster or other trainer like plane, the LA .65 could haul quite a load turning a 14x6, if larger 120 sized plane I'd say a SuperTigre 2300 conversion would work well turning an 18x8.

The K&B .65 Sportster is great for heavy lugging near the 10cc displacement area. I agree with choosing the G2300 for larger applications.


Ed Cregger

Hobbsy, just really noticed your beautiful engine test stand.

It looks like a PSP one and I must say the design and manufacture looks excellent in every way.

It makes mine look agricultural by comparison!

Looks good, It might not take a SuperTigre 4500 too well but many many others.