Author Topic: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’  (Read 8990 times)

Offline Ramon Wilson

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Hi guys,

With the base and parts for the Corliss engine awaiting painting I thought I’d have some time on a couple of diesels that have been on the cards for rather too long. Though some parts of this project have already been made this won’t be a build log as such - the Throp will take precedence - but will be more on an ‘as and when’ basis. I would like to think however that I would have them finished for running at the Forncett ‘do’ in October.

Perhaps first however a little bit of background is in order….

The ED (Electronic Developments) 3.46 cc 'Hunter' has long been a 'favourite' engine. This one, still with original box, was recently passed to me as a gift from the original purchaser by my long time control line model flying friend John Leonard.



 I think I said somewhere else it hadn’t been run for forty years. John assures me it hasn’t been run since just after purchase in the mid 1950’s. Despite the dirty appearance it certainly doesn’t look as if it’s had much running though I notice it has a replacement screw at some stage. The nice thing though is it has an original needle and spray bar which can be copied.


Until this example then I had only owned an original one for a very short period when I was around 14-15 years old. I had bought it second hand and built a KeilKraft Pacer control line team racer to fit it into. Anyone remember this ad?



On it's initial outing I had had several nice flights before clipping the prop (engine was stopped) on landing. Nothing was thought about this until starting it for the next flight - that clip had broken the crankcase all around the front bearing housing where the wall section was very thin due to the bearing housing behind.  I replaced the ‘case but like so many engines over the years it disappeared, no doubt to fund purchase of another engine.

A couple of years ago John (L) asked me if I could have a look at his version, which was binding on bottom dead centre. A strip down revealed nothing more than many years of languishing castor oil crud that had gone rock hard and the con-rod was hitting this as it passed. Scraped off and cleaned with solvent it was back to running state in very quick order.

The Hunter - in it's day - was (to a young teenager) a big engine and had a reputation of being a finger grabber - a reputation well deserved I should add  ::) and this proved just the same but having never used anything but the digits to start an engine why change the habit of a lifetime :D The crackle of the exhaust in the workshop door soon had ideas of getting one for myself just for nostalgia sake but as it sat on the bench waiting for JL to pick it up I became to realise just how much I actually liked it's shape. The thought of a 5cc version didn't take long to manifest itself and a quick check of the small increase in dimensions required showed that it was significant enough to have a visual difference.

A GA was laid out and a preliminary set of drawings done ….



……  and the usual start made to hack out a crankcase from ali block. There would be a couple of challenges - particularly around the bosses where the backplate screwed to. Unfortunately at around this time my interest was distracted elsewhere (as it does  ::)) and the roughed out rectangular blocks albeit with the internal dimensions finish machined and the bronze bush installed were popped in a box and gradually forgotten.

Sometime last year I had need to turn something non modelling orientated from ali and the thought occurred to ‘just’ turn the outer front ends. All the old buzz quickly returned and again in quite a short time I had not just two crankcases but the backplates and venturi’s too. Despite a serious ‘plastic distraction’ at the time this was the catalyst for the resurgence of interest in machining and the desire to do something about those languishing Throp engine parts. Unfortunately no images of machining the crankcase parts were taken but it was machined from solid much as the ETA and Atomatic engines described previously on here.



The cases were easy enough to machine – as said, only the bosses where the backplate screws to presenting a small challenge but once done there they have sat waiting along with material cut off for the cylinders and crankshafts.



I guess some you will remember this classic old British design with a firm degree of nostalgia and hopefully, on that note, will be of interest.

I’ve been turning the cylinder heads this morning and so far the ‘cases, cylinders and crankshafts have been machined. There’s a definite whiff of ether in the air


Regards - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Online Vixen

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #1 on: February 22, 2018, 01:42:06 PM »
Hello Tug

I remember the Hunter very well. My Dad gave me his 3.5cc Hunter engine to play with as soon as I had become a teenager. I remember receiving many, many painful wraps across the knuckles before I learned the technique of starting this monster by hand. A hefty flick and follow through, don't tickle it.
I flew it in several control line planes that I had designed and built, all with the rather non original name of "HEaD Hunter" Well I thought it was a good name at the time.
It is the journey that matters, not the destination

Sometimes, it can be a long and winding road

Offline b.lindsey

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #2 on: February 22, 2018, 02:32:52 PM »
That's quite a nice start on both of them Ramon. The crankcases look better that the original.

Bill

Offline Admiral_dk

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #3 on: February 22, 2018, 05:03:11 PM »
Oh Boy another fantastic build of an classic Aero Diesel from you  :whoohoo:

I do admire your work on the Corlis, but this kind of engine is really what ticks all the boxes for me  :)

Was the original also an oversquare design as yours or did you "just" increase the bore ?

Best wishes

Per

Offline Ramon Wilson

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #4 on: February 22, 2018, 11:08:19 PM »
Hi Mike - yes it certainly lives up to it's reputation - hate to think what these 5cc versions will be like as I've had some good old whacks from them. Never fear though I certainly won't be timid with it  ;D

Hi Bill - well to be fair it's looking pretty manky in the pics but I did clean that all off last night so it looks much better - just need to give it a nice run and get that smell of diesel in the workshop  :)

Per - I have scaled this up from the original at 1:1.13 on all parts throughout. Though that doesn't seem much difference I did not want to exceed 5cc. Side by side once finished there'll be a noticeable enough difference.

I'll pop some more pics up tomorrow

Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Online Vixen

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #5 on: February 22, 2018, 11:24:21 PM »
Hay Tug

When my Dad first bought the ED Hunter, we were living in one half of an old vicarage, somewhere in the wilds of Herefordshire. One day, while the engine was being 'run in' on the bench, the vicar called by to see what all the noise was about. He took quite an interest in what we were doing and even asked if he could have a go at starting the engine. Your well ahead of the story by now. The Hunter lived up to it's reputation and gave the vicar a nasty whack across his fingers. I was a young lad and had never before heard such colourful language. And him a vicar? Where did he learn it? Must have been from his sinful parishioners.

Mike
It is the journey that matters, not the destination

Sometimes, it can be a long and winding road

Offline Dave Otto

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #6 on: February 23, 2018, 12:59:08 AM »
Very nice Tug!
Everything looks great so far.


Dave

Offline Ramon Wilson

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #7 on: February 23, 2018, 08:40:14 AM »
Hi Dave - good to see you here thanks for looking in  :ThumbsUp:

Nice story Mike - quite an eye opener at that age eh?  :o

I've had some seriously good whacks over the years but nothing save the very first of any consequence. That first was done by a little AM 10 and split my forefinger open along its length, the Frog nylon 7x6 laying the flesh back as easy as any razor.

Had a good one captured for posterity by Rod (Tangler) who took it at Guilford to the amusement of the onlookers. If you take a look at this it will bring a smile to your face - <a href="https://www.youtube.com/watch?v=nhsj0N5H_0Q" target="_blank">http://www.youtube.com/watch?v=nhsj0N5H_0Q</a> - I think I may have used the same expression as your vicar  :Lol:

Despite the potential for some 'bruising' I still prefer to start by hand, in fact I have never used an electric starter, and never would on a diesel anyway but I only use wooden or nylon props though they can still produce some nasty results if careless.

Hope to put some more pics up later.

Tug


PS
Could someone tell me how to embed the You tube clip so you can watch it in the post as opposed to clicking on the link. I did manage to get it embedded but it had the link text all around it
« Last Edit: February 23, 2018, 10:28:55 AM by Ramon »
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Online Jasonb

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #8 on: February 23, 2018, 10:15:14 AM »
Ramon just copy and past the full link from your browser and paste in straight into the post, very easy to do on this forum.

So paste this without the gap https://w w w.youtube.com/watch?v=nhsj0N5H_0Q&feature=youtu.be

<a href="https://www.youtube.com/watch?v=nhsj0N5H_0Q" target="_blank">http://www.youtube.com/watch?v=nhsj0N5H_0Q</a>

Offline Ramon Wilson

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #9 on: February 23, 2018, 10:30:50 AM »
Thanks Jason - as you see 'simples' - when you know :)

Using the url bkts was the mistake  ::)

Ramon
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline b.lindsey

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #10 on: February 23, 2018, 12:49:15 PM »
Nice clip Ramon....good to see that no blood was drawn either. Quick questions though from someone having no experience with these diesel engines...do they run on straight diesel or are there also additives within the fuel as can be the case with glow engines? Just curious  :thinking:

Bill

Offline tangler

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #11 on: February 23, 2018, 01:11:23 PM »
Bill,

Roughly equal parts kerosene, ether and castor oil with a dash of isopropyl nitrate ( to make the engine "pop"  ;)

Cheers,

Rod
« Last Edit: February 23, 2018, 01:19:41 PM by tangler »

Offline Ramon Wilson

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #12 on: February 23, 2018, 01:19:27 PM »
Hi Bill, No, no blood and it does look like a quick recovery but I assure you it did bloody hurt and for some time too :D I usually have a stout glove on but had gone to Guildford with no intention of running them. Didn't take much persuasion from Eric to change that though  :D

'Diesel' is a bit of a misnomer really. The fuel is usually a mixture of Oil (usually castor but not always), Ether and Paraffin (Kerosene)

Basic mix is 33:33:33 but that is very rarely used. Normally the paraffin is the greater portion with the oil the minimum. An additive of a nitrate to improve ignition is also usually used.

Nitromethane which is used in glow fuels in varying proportions, sometimes to very high percentages, to enhance performance is not used and as far as I am aware certainly outside of the competition arena there are no similar additives that are used in 'diesel fuel'

Regards - Tug

Ah I see Rod has beat me to it  :D
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline b.lindsey

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #13 on: February 23, 2018, 01:34:29 PM »
Thanks Rod and Ramon. Glad I asked :)

Bill

Offline Tennessee Whiskey

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Re: An English Classic ? A 5cc version of the ‘ED Mk IV 3.46 Hunter’
« Reply #14 on: February 23, 2018, 08:04:20 PM »
Yeah, yeah, ya chipped tis un up jas ta git me arse in teh ol’  shid eh: blasted man ( hey I’m learning  :lolb: :lolb:)
In petro chemical terms, diesel is any fuel that is used for combustion without spark. Here in the land of freedom dollars and corruption, it’s pretty much like distilling a good whiskey. Jet Fuel A is the primo, and IIRCC, believe it or not, kerosene (paraffin) is next , then come the stuff you use in your auto or tractor, and then come the stuff you keep ya bum warm wit. Sad thing about it: last time I was at our local airport, getting 100LL for my old car, Jet A wasn’t a few cents higher (minus taxes mind you) than heating fuel. Must be that supply and demand thingy  :lolb:.

Whuskey

 

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