Oddball engines and prototypes

[T.W.R]

I will be looking for a 29 Control line speed model. But with 2 lines not monoline.
I have heard of a Doonside Mills, and thought the Doonside was the copy. I did not realise that the Doonside was the original engine.
Neil

Got a few control line speed model plans, a lot of the control line plans are stunt models including a MkV spitfire and a rather cool looking bi-plane

Mills copied the Doonside and extended the shaft etc

[WilDun]

I will be looking for a 29 Control line speed model. But with 2 lines not monoline.
I have heard of a Doonside Mills, and thought the Doonside was the copy. I did not realise that the Doonside was the original engine.
Neil

Doonside in Australia copied the original British Mills (which was I believe was originally a wartime Swiss design), and made a very good of copy of it too!
I still have an original British Mills .75 tucked away somewhere, - they were great little beginner's engines and much easier to start and tune than the average small diesel of the day because of their unique transfer design producing excellent atomisation of the mixture and good torque - not so fantastic in the high performance department though!

[T.W.R]

Doonside copied the original British Mills (which was I believe was originally a wartime Swiss design). I still have an original British Mills .75 tucked away somewhere, - they were great little beginner's engines and much easier to start and tune than the average small diesel of the day because of their unique transfer design producing excellent atomisation of the mixture and good torque - not so fantastic in the high performance department though!

That's interesting because I've got a copy of Aero Modeller Jan 84 (Britsh Publication) sitting beside me now with a article on "a guide to free flight scale" written by Bill Dennis that talks about the Mills and it's history and suitability for the class

[WilDun]

Ha your thread Glenn was the original poster so if any one can lay claim to owning this thread it's Husaberg...so dial back the arrogance

We both discussed it, Husa got it going and it has gone along sweetly since then, both of us getting along fine until a cantankerous old bastard with a frazzled brain talking like a pre-teenage kid turns up determined to wreck it!

But this does have a familiar ring to it! a smell that will never go away!

He's back folks! JAW, HEMI MAKUTU and now his present name TWR! and there is a certain other person of interest (known to be an associate? - or is it a crony - maybe yet another aka?).

[T.W.R]

We both discussed it, Husa got it going and it has gone along sweetly since then, both of us getting along fine until a cantankerous old bastard with a frazzled brain talking like a pre-teenage kid turns up determined to wreck it!

But this does has a familiar ring to it! a smell that will never go away!

He's back folks! JAW, HEMI MAKUTU and now his present name TWR!

You need to go have a masti to relieve your pent up frustration

[Pursang]

Been some chatter, about the place, on the value or otherwise of exhaust ports that are not dependent on tuned pipes.

Have a close look at this Excelsior board track racer.



Cheers Daryl.

[WilDun]

Not that it really matters, but just to clarify what I said regarding the "Doonside Mills", - just scroll down a bit and you'll get an article on Mills engines.
Maybe we'd better move on!

http://www.modelflyingnz.org/Docs/In...20No%20143.pdf

[Pursang]

Auxiliary Exhaust ports. Just above BDC



My thoughts... The exhaust ports provide additional Bleed-down and reduce pumping losses on the Exhaust stroke.

(Bet they sounded Awesome too!!!)

On the Inlet side, inertia of the incoming charge will force any Hot, Residual, exhaust gas out of the cylinder around BDC.

Cylinder will be filled with fresh cooled charge for compression & ignition.

This system was also explored in Ford flat-head V8's, for land speed racing, in the early 1950's.

The flathead V8 is Very exhaust limited. 4 cylinders into 3 ports, passing through the block, from inside the V to the outside.
Ducts were restricted and exhaust heated the block & cooling system substantially.

Other options included reversing the flow, with 8 exhausts from inside the V, and 6 inlets from the outside.

Development stopped with the increased availability of 'modern' OHV V-8 engines.

Here are a couple of pics of a reversed flow V8-60 in a midget.


cheers, Daryl

[emess]

Here is something a little less vintage, that I posted on the French Pit-Lane forum: http://www.pit-lane.biz/t6246p25-gp1...vermars-part-5
Attachment 331772
.

Frits, how do you calculate/measure the effective port opening times?

Thanks,
Mick

[Frits Overmars]

Frits, how do you calculate/measure the effective port opening times?

It's a good question Mick, and I'd like to oblige, but I'd need a bit more than the 11 words that you used. More like 11 pages...
It depends on how steeply the cylinder pressure falls off after Ex-open, which in turn depends on exhaust gas temperature and pressure, and on the rate at which the blowndown angle.area increases per crank degree. In a shallow port this rate is rather low, so there will be a bigger difference between its geometrical and effective opening points, as opposed to the geometrical and effective values of a wide port.
But angle.areas are only part of the story; another important factor is the flow coefficient of the upper part of the port. This is where the radiused top edge of the Aprilia exhaust port and its turbulence-suppressing duct shape come into play. In short: it's a lot of theoretical and practical work.

[Grumph]

Been some chatter, about the place, on the value or otherwise of exhaust ports that are not dependent on tuned pipes.

Have a close look at this Excelsior board track racer.

The 8 valve Indians often had similar barrel ports as auxiliary exhausts. The old man was around and racing in the days of mile grass tracks here and once told me that when they were fired up it didn't pay to be alongside as you got showered in oil and unburned fuel....

Here are a couple of pics of a reversed flow V8-60 in a midget.

cheers, Daryl

That's a beautiful restoration - much better finished than it would have been originally, LOL.
I look at the length of the inlet tract runners and wonder if preheating before starting is going to be needed to avoid flooding the cylinders with unburned alky...

[guyhockley]

http://www.gasenginemagazine.com/gas...iliary-exhaust

[Pursang]

A very clever gentleman named Dennis Jones (obviously No relation) built this around WW2.





A ban on supercharging in M/C GP, after the war, rendered it obsolete.
(I bet that was discouraging)..Bugger!

Pics from here:http://http://way2speed.blogspot.com/2013/09/jones-motorcycles.html

Cheers, Daryl.

[husaberg]

A very clever gentleman named Dennis Jones (obviously No relation) built this around WW2.





A ban on supercharging in M/C GP, after the war, rendered it obsolete.
(I bet that was discouraging)..Bugger!

Pics from here:http://http://way2speed.blogspot.com/2013/09/jones-motorcycles.html

Cheers, Daryl.

He build other fours as well more conventional ones
Pretty sure i have posted some before.

[Pursang]

That's a beautiful restoration - much better finished than it would have been originally, LOL.
I look at the length of the inlet tract runners and wonder if preheating before starting is going to be needed to avoid flooding the cylinders with unburned alky...

So true, most restorations of vintage racing machines are far "Flasher" than they were run, back in the day.

Racing Friday & Saturday nights on tracks 750klm apart, there wasn't much time to do much more than fit new big-end bearings and knock out the worst dents.



Regarding starting with the loooong intakes, they might have used petrol or ether to get it running, before opening the shut-off valve from the pressurised fuel tank??
(Hand pump on the outside of the cowl.)

Cheers, Daryl.