Nemett Lynx 15 cc 4 Stroke I/C Petrol Engine

[Brian Rupnow]

Bronx---There are some very smart builders out there. Most people who are well advanced in 3D design don't just want to copy someone else's engine. We want to add our own personal touch and design something that has never been done quite that way before. It is almost impossible to design something so totally new that it has never been done before by somebody, somewhere. Almost all "new" mechanical designs are concepts that have been done before, just arranged a bit differently. Thats where a lot of the fun is for me.---Brian

 

[Brian Rupnow]

I just ordered the same Model Engineer magazine (reprint) that appears in the very first post. I may not build the Lynx myself, but dang, I've got to keep up with what you guys are doing!!!---Brian

 

[Swifty]

Brian, I'm with you about the look of the toothed belt, spoils it a little bit. However that's not stopping me from building one. Maybe a cover over the belt and top wheel will work.

Paul.

 

[Brian Rupnow]

Swifty--Take a look for posts showing the Hoglet engine. It has a perfect example of exposed pushrods and rocker arms. To some it may be a step backwards, but once I get my set of plans I may change the design of the belt driven camshaft to mimic that on the Hoglet.---And i will probably do the design in British Imperial, not metric.---Brian

 

[Swifty]

Brian, I can see where you are going with the design, a bit of a rehash and you can have pushrods. You Canadians have to let go of the imperial system, metric is so much easier.

Doubletop, did you mirror image your picture of the completed engine, or did you build it that way?

Paul.

 

[Brian Rupnow]

Swifty--Ah, the magic of 3D cad. I can design the engine in either metric or imperial---it makes no difference. The parts are modeled at 1:1. Where the truly fascinating part comes in is when I generate detail drawings. By simply changing a setting on my system I can have the dimensions printed in metric, or imperial, or even in both. I don't type in any of the dimensions. The math data is input into the part files when I create them, and the actual drawing is almost fully automated, and the software picks up the information for the dimensions from the math data I use when modeling the part to create the dimensions. I am an old dog, and worked fully in Imperial until I was about 26 years old, when suddenly the world tilted on its axis and Canada converted (what a laugh) to metric. I have used both systems ever since, but at heart I am still more comfortable with Imperial.

 

[doubletop]

Hi Pete,
You are my hero/meister. When can we see video of running engine?
Will be late next week to start turning the C.I. Liner. Will proceed step by step as per Best of Magazine. Paul Swifty is about to get started.

Would you be running with dry crankcase or lube oil topped up Crankcase?.

I found that the oil level self regulates once it gets below the level of the bearings the flow stops coming out of the nose and the crank counter balance dips low enough and is big enough to chuck the remainder around adequately.

 

[doubletop]

I have no idea what is going on here? This is the !!!!!th attempt to embed the video I've tried all the tags, the video link comes up in the edit screen and then everything disappears after the save. Even text after the video

http://youtu.be/1BVOu0xfaPw

You'll just have to make do with this link

<iframe width="420" height="315" src="//www.youtube.com/embed/1BVOu0xfaPw" frameborder="0" allowfullscreen></iframe>

Pete

 

[Brian Rupnow]

I have what I think is a legitimate question. All of the video's I have seen of the Lynx engines running show it turning a propeller. I don't see any sign of a flywheel. Does the propeller stand in for the flywheel? Will the engine run without the propeller on it? I know that when an engine turns a propeller, it puts a nice constant load on the engine that increases with engine RPM. Does the Lynx NEED this load to run smoothly and not falter or rattle? I absolutely KNOW that if I built an engine with a propeller on it, the first thing I would do after the engine started and the propeller became a blur, I would stick one of my appendages into the damned propeller!!!---Brian

 

[Swifty]

Doubletop, did you mirror image your picture of the completed engine, or did you build it that way?

Paul.

Sorry, I only just realised that the picture on the front of the magazine is mirror image. I must pay more attention to the drawings.


Paul.

 

[doubletop]

Brian

The drawings include a water jacket and flywheel. In my case I did the Bobcat twin as water cooled so went for the air cooled version this time.

Pete

 

[Swifty]

Gus, I've started to machine parts already, starting with the crankcase. Just thought that I would warn you that on the drawing, all lines wether they are profiles, hidden lines, bolt hole circle sizes etc are all drawn as solid lines. It can get confusing, so watch out.

Paul.

 

[Swifty]

Brian, I'm with you regarding the propeller, I will be making a flywheel to run the engine and probably buy a cheap prop for display purposes. I've made it to 62 years with all my fingers intact after a working life as a toolmaker and doing my fair share of press trials, I don't intend to run risks now.

Paul.

 

[Jasonb]

Brian, just for you this one is running the marine flywheel and water jacket cylinder.

[ame]https://www.youtube.com/watch?v=wTq0ogyTFEc[/ame]

Malcom originally just had number/letter manes for his engine, only changing to the big cat makes at a later daye so you may want to also search for NE15S (Nemett 15cc Single) though there are a few different spellings of Nemett.

One thing to bear in mind with the flywheel is that the Lynx and Bobcat are faster running engines than say the Hoglet so a large dia flywheel will have a lot more innertia so throttle responce will be affected so a bit slow to change speed when you blip the throttle and at 7500rpm will put a lot of load on things and will need to be well balanced.

J

 

[doubletop]

Brian asked me what the terminal was doing on the video and how advance adjusted the rev range so much. It doesn't.

The PIC software is controlled by the PC and allows the advance curve to be set up on the fly, with the engine running, in one of two tables of 32 advance steps across the rev range. It also allows pulse width to be changed, a sofware adjustment of the hall sensor trigger point and some other minor parameters. In order to help do this I added a servo output to control the throttle to manage one of the variables not related to the ignition, that’s what I was adjusting.


[ame]http://www.youtube.com/watch?feature=player_embedded&v=1BVOu0xfaPw[/ame]



Pete

 

[ICEpeter]

Jason,
While watching your video, I noticed your use of a stainless steel corrugated exhaust pipe from the engine to your silencer. Could you be so kind and let me know the ID and OD of the corrugated pipe and where you obtained it from? I am looking for a source for this kind of piping. Thanks.

Peter

 

[Jasonb]

Not my engine, but I have seen the stuff somewhere, wil rack my brains now until I remember

J

Edit, came back quicker than I thought

http://www.macgregor.co.uk/saito/exhausts.htm

 

[ICEpeter]

Thank you much, Jason

Peter

 

[gus]

Looks like Gus is getting all the expert help to make the construction of Nemett-Lynx Engine a success!!!

Maestros .Thank You. This really a shot in the arm.

 

[gus]

Brian, I'm with you regarding the propeller, I will be making a flywheel to run the engine and probably buy a cheap prop for display purposes. I've made it to 62 years with all my fingers intact after a working life as a toolmaker and doing my fair share of press trials, I don't intend to run risks now.

Paul.

I am going for flywheels. No props. This engine is too big.At this hp and speed , my fingers will shatter. Other than a left thumb which cannot bend fully,I have no desire to have my other fingers hurt.
I have to make up for mother's day and taking the darling boss for DimSum Lunch at the Sands Casino. No worry. I win everytime.That I do not gamble and so having not lost any money.I have won. Ha ha.
Gus not gambling. Its proven that Gus has no gambler's good luck.