Help on a Matador four stroke engine build please.

[Mike SuffolkParticipant @mikesuffolk]

I'm just embarking on building a Matador 60 four stroke, as published back in the 80's I believe. I wondered wheher there was anyone who had built one who could say whether there are any errors on the plans? I'd hate to put in a lot of work to find parts don't fit. Any help much appreciated – thanks.

[Mike SuffolkParticipant @mikesuffolk]

[Roderick JenkinsParticipant @roderickjenkins93242]

I've built one, 20 odd years ago now. I don't remember any issues with the drawings but I do tend to make things to fit rather than make a collection of parts and then assemble them all. The problem I had was with the bronze inserts for the valve seats. There is so little meat on them after drilling all the holes that I couldn't get them to stay put in the cylinder head. I ended up making a solid bronze head that is kept in place by the remains of the aluminium head with the middle cut out. I also forgot to make the front housing threads left hand which meant that I had to peg it to stop it unscrewing.

It ran very well with a cast iron piston ring in the mild steel cylinder and I must have run it for some tens of hours all together with no obvous signs of wear. It is enormously satisfying when one fires it up and it runs for the first time. Incidently, I could feel very little compression on mine when turned over by hand but once an electric starter got it going it sings along very nicely. I worked out some hp figures based on the prop and rpm. If I can find them I'll let you know.

have fun

Rod

[Mike SuffolkParticipant @mikesuffolk]

Thanks Rod. So far, from the drawing, I think the rocker support bar is out by about 1/32 and I have found 3 very slightly different spacings for the valves – I'm hoping that's all. I did wonder about the valve guides/seats myself, so I'll have to bear in mind your solution. As for the LH thread – I have just put a bit of scrap in the lathe to test a thread before I committ to the crankcase, so I hoping to get that right.

Do you remember how you tackled the crankshaft? Did you bore a bit of ally off-centre for the main shaft to fit in, stick it in the 3 jaw and then turn the big end?

Thank for the comments – good to know its all possible.

Mike

[Roderick JenkinsParticipant @roderickjenkins93242]

Mike,

I made the crankshaft from a large HT bolt. The crankpin hole was drilled using my Arrand milling spindle on the cross slide with the crankshaft held in the 3 jaw chuck. I then pressed in a piece of silver steel with a shoulder turned on it for the crankpin

I've (amazingly) found my power curve. I used the prop factor equations from Martin Simons "Model Aircraft Aerodynamics". Maximum power was 0.44 HP at 8000 rpm with a 12×6 prop. Maximum rpm was just over 9000 with a 10X6. I thought that was pretty impressive for a home built. This was using the carb as described and (probably) 5% nitro.

cheers

Rod

[Roderick JenkinsParticipant @roderickjenkins93242]

I should add that it was making the cams for this engine that drove me to write a computer programme to derive the co-ordinates for cutting the cams on a milling machine using a dividing head. See the resources page at Ron's modelenginenews.org.

Rod

Edited By Roderick Jenkins on 11/01/2013 09:42:35

[thomas oliver 2Participant @thomasoliver2]

I built the Matador when it was first published, and had no particular problems with dimensions. The valve pockets were tricky in bronze but I managed them ok. I mounted the Merco type copy carb on a downdraught intake to lower it to approximate tank level for aircraft. It only needs about three turns of the prop with the finger choking it and it is away every time. The robust cam gear augers for a long life. I do not know from where I sourced the particular piece of C.I. I made the ring from, but when I split the ring it seemed very springy so I did not heat treat it and the compression has remained very good, after a good many runs. I bought the gears from SH. Muffets – very good if a bit pricey.

I remember I machined the cylinder with an HSS parting tool without bother 'til I had to face the lower face of the last fin, when the flex of the tool work hardened the face and took the edge right off. I then resorted to a TC tool to finish it OK.

All in all, a good design, resulting in a pleasant, powerful engine.

Tom.

[Mike SuffolkParticipant @mikesuffolk]

Thanks Guys for the comments. I feel a little more confident about having a go, knowing that there should be no major issues with the plans.

9000 on a 10*6 will be good enough for what I have in mind, so I'll be happy if I can manage that too. I'll also check out your co-ordinates for the cams – sounds like the way to go.

Thanks again,

Mike

[Mike SuffolkParticipant @mikesuffolk]

Rod and Tom,

Thanks for your original posts which gave me confidence to get started, and also for the pointer to the Model Engine News site for the cam profile info.. My engine is now complete with maybe 30 minutes of running. Starts easily and purrs nicely. A lot to be said for the design I guess. I had no real problems with the build – just took it slow – the main problem was with my brain at times.

On a 12×5.5 prop I'm getting around 8500rpm which I'm very happy with and will be more than I need for what I have in mind.

Cheers,

Mike

[Roderick JenkinsParticipant @roderickjenkins93242]

Mike,

Well done and good progress. You couldn't treat us to a picture could you? (or even a video).

Cheers,

Rod

[Mike SuffolkParticipant @mikesuffolk]

Here are a few images Rod, not sure how to get a video in

[Neil WyattModerator @neilwyatt]

I've often wondered about the power of such engines. ETW's Kiwi Mk 1 produced 5/8 BHP from 15cc, I wonder what Kiwi Mk 2 managed?

Matador is similar OHV layout to Kiwi and 0.44 BHP from 10cc is proportionally the same as Kiwi 1 (given the inaccuracies of measurement).

I wonder how they compare to the more modern OHC design of the Nemmet Lynx, also 15cc.

Neil

[Roderick JenkinsParticipant @roderickjenkins93242]

Mike, very nice indeed – much prettier than mine. I posted a video of my Wyvern by putting it on Youtube and then posting the link using the Youtube button in the reply box.

As to Neil's point, if anybody would care to give some figures for the maximum speed with prop diameter and pitch for their Lynx then I can calculate the HP, at least to the same accuracy as my Matador.

Cheers,

Rod

[JasonBModerator @jasonb]

Malcom said he got 7500rpm on a 14×7 prop if thats of help. Would you be able to post the Formula Rod as I've just started an aero engione and it would be nice to work out what its producing when and if it runs.

J

Edited By JasonB on 15/04/2014 07:16:16

[Roderick JenkinsParticipant @roderickjenkins93242]

25 odd years ago I constructed some graphs of BHP versus rpm for various prop diameters and pitches. I'm not quite sure now where I got the calculation from since it is not spelt out (as I thought), in Simons' book. However, I've found a formula on the net which seems to pretty much agree with my figures:

BHP = 7.105*10^-18*D^4*P*rpm^3 where D is prop diameter and P is the prop pitch (both in inches) and rpm is revolutions per minute (that's 10 raised to the power of -18, D raised to the 4th power and rpm cubed)

This gives 0.81HP for the Lynx on a 14×7 at 7500

and

0.45HP for my Matador at 8000 on 12×6

This figures are pretty approximate since they make some assumptions – principally air density. The proper way to measure the power of an engine is to measure the torque. When I was fiddling around with these engines all that time ago I made a simple dynamometer to measure the torque reaction. The problem was damping the vibration, which is inherent in these single cylinder engines. Perhaps I'll look out the bits.

Jason, you have pm.

HTH

Rod

 

:

Edited By Roderick Jenkins on 15/04/2014 13:03:36

[Neil WyattModerator @neilwyatt]

That's interesting Lynx runs a lot faster than Kiwi, and gives about 20% more power.

I remember reading an article in an old Aeromodeller..They had a series of props which they had tested against a dynamometer, and used for engine reviews. Some of them were well 'off the line', but it meant they had an rpm/power curve for each test prop that allowed them to easily and accurately test engines. They said teh main error source was differences in prop pitch and detail design.

Neil

[Four stroke FredParticipant @fourstrokefred]

Mike Your engine looks very good and it sure is a thrill when they fire up for the first time. In the 1970s the German firm of Graupner produced a set of props for measuring the power of model aero engines. They were mounted in a special case and had power graphs for each prop – I think they were quite expensive! I would have loved to have had a set but cost prevented purchase.

George.

[Kevan Gillings 3Participant @kevangillings3]

HI, I am thinking about starting the construction of the matador twin,i know the cam gears are unobtainable from the original suppliers ( S H Muffat)

Has anybody got an idea of another supplier ?

Kevan Gillings

[Roderick JenkinsParticipant @roderickjenkins93242]

Kevan,

For my single Matador I bought my 45 degree helical gears from HPCgears.com. What gears does the twin Matador call for?

HTH,

Rod

[Kevan Gillings 3Participant @kevangillings3]

Hi, thanks for the information, the flat twin uses the same gears ,with two camshafts with there own gear.

Will try HPC.

do you have a photo of your motor ?

Kevan

[Former MemberParticipant @formermember32069]

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[Ian Skeldon 2Participant @ianskeldon2]

I have never built my own aero model engine but I have owned a few Laser engines (and still do), British 4 stroke engines, very reliable and fairly powerful.

I can't say for sure, but maybe you could contact them and buy gears from them? Link below

Laser Engines

Edited By Ian Skeldon 2 on 26/04/2019 21:26:20

[Roderick JenkinsParticipant @roderickjenkins93242]

Posted by Kevan Gillings 3 on 26/04/2019 18:36:31:

do you have a photo of your motor ?

Kevan

Well, you did ask

Needs a bit (!) of refurbishment. It used to run very nicely…

Rod

[John OlsenParticipant @johnolsen79199]

I seem to recall that someone built a proper dynamometer for testing model aircraft engines, and it was described in I think Aeromodeller. Peter Chinn did most of the testing for Aeromodeller so I would guess he might have been involved.

John

[Former MemberParticipant @formermember32069]

[This posting has been removed]

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