Since 2001 we have been well known for making various types of high quality Stirling engines. Last year we launched our new Nano Cannon Stirling engine through Kickstarter. The project was very successful and we were praised by many backers for the excellent engineering of the product and speed that we delivered them. Many backers said it was by far their best experience of Kickstarter. We now have a new engine ready to launch. This time it is not a Stirling engine… this time we have developed a Manson engine.
Our Project - Nano Disc Manson engine
For this Kickstarter project we decided to venture away from Stirling engines and develop a Manson engine. We wanted to keep the design similar to our previous Nano Cannon engine so we kept the same base and burner, which runs from denatured alcohol (methylated spirits). This new Manson engine is called the Nano Disc. Our design approach for this engine has been the same as for all our engines, which is to fully design and simulate the mechanism in CAD before making any parts. Prototypes then get made and tested, small adjustment are made, new parts designed, made and re-tested until the engine is perfected. From the first prototype to the last prototype a huge increase in performance was achieved.
What is a Manson engine and how is different to a Stirling engine?
Stirling engines convert a temperature difference into motion. There is a hot side and a cold side to the engine. Provided there is a large enough temperature difference the engine will run. Stirling engines work by cyclically heating and cooling the air inside the main chamber. As the air heats up it expands, and as it cools down it contracts. This expansion and contraction drives a small piston which in turn drives the flywheel. Stirling engines have a mechanism for cycling the heating and cooling of the air built into the engine in the form of the displacer which pushes the air between the hot and cold sides. The displacer is driven by a connecting rod connected to the flywheel.
In a Stirling engine only the air within the engine is used, it does not draw in or expel any air. It is effectively a sealed engine. A Manson engine is very similar to a Stirling engine but with two major differences. Firstly a Manson DOES draw in and expel air. Secondly a Manson engine is able to have a single connecting rod and counterintuitively the displacer piston and power piston are on the same shaft and move at the same time. A Manson engine cycle is a little harder to grasp.
Technical details on the Manson cycle
At the top dead centre and bottom dead centre valves open briefly. The rest of the time the valves are closed. The valves just open to surrounding air. Both the displacer piston and power piston move together in the same direction at the same time. The clever bit is that at the end of each stroke a valve is opened. This releases pressure or vacuum so the next cycle can begin.
The Manson cycle can be summarised into 4 parts:
- When heading towards the heat, the displacer piston is shuttling air inside the engine to the cold side, cooling and contracting the air, which in turn pulls on the power piston.
- A valve is briefly opened relieving the vacuum pressure. This prepares the engine for the next stroke. The flywheel provides energy to push the engine into the next stroke.
- When the pistons are heading away from the heat source the displacer is shuttling air inside the engine to the hot side, expanding the air which builds up pressure and drives the power piston.
- A valve is briefly opened relieving the pressure inside the engine. This prepares the engine for the next stroke. The flywheel provides energy to push the engine into the next stroke.
Some brand new innovations
While developing and prototyping this new Nano Disc engine our workshop manager and designer Chris Guise had the idea to improve the design and performance of the conventional Manson engine. The improvements simplify the design, reduce production costs and improve performance of the engine. We are looking into applying for a patent for this improved design hence we can’t state the exact improvements yet. However once the patent has been applied for we can share the details. This will be during the Kickstarter project funding stage. We think this makes it a new type of engine: A Manson-Guise engine.
Pleasant noise of the Nano Disc engine
Manson engines are well known for the distinctive noise they make, and the Nano Disc engine is no exception. In operation the Nano Disc engine makes a lovely burbling purring noise.
Runs in either direction
Two types of engine on offer
Our new Manson engine is called the Nano Disc, and we have two types on offer. Our standard Nano Disc (shown below on the right) has a horizontal flywheel. It seems a bit unusual to have a flywheel like that but it works and we think it looks good. However for those of you that like your flywheels to be vertical we have a second version for you. It requires one extra part plus some more holes to be drilled and threaded into the brass cylinder. We call this the Nano Disc Vertical (shown below on the left). Two options, your choice, performance is the same.
Piston with NASA-developed Tungsten Disulphide coating
We have recently come across a special coating process developed by NASA in the 1970s. They needed a way to lubricate mechanical surfaces in space. Oils were out of the question because of the extreme temperatures, so dry lubricant was required. Amazingly they found a tungsten compound that could be applied to parts. The tungsten coating is permanent, is very tough and wear resistant, is ultra slippery which reduces friction and increases performance. Furthermore it can handle high temperatures and never needs maintenance. It basically removes the need for lubricants. Other than the cost it has no disadvantages. We have been testing it recently and think it is brilliant.
So we are offering this coating as an OPTION on the rewards.
Precision custom laser engraving
Wouldn’t it be nice to give a little bit of personalisation to your engine. Well we can laser engrave the engine base for you. You may want to give the engine as a gift and what better way to make it more personal than having it engraved. We can only engrave in one colour (white) and realistically only have a couple of lines of text. But the message can be as personal as you like.
Protective glass dome
History of Stirling engines and Manson engines
Why we need your help
All our engines take months of designing, trying out various mechanical linkages and parts, and then building prototypes to perfect a new engine. Just like previous development of engines, it takes numerous design iterations to get to our final working prototype. We could start producing a small batch tomorrow and with a few weeks have a small number of engines built, but small batch runs are inherently expensive. Why is a small batch run expensive? All the parts will be machined on our own lathes and milling machines at our workshop. But the CNC machines first need to be programmed and set to run a batch of parts; usually taking hours for each component. CNC machines are not cheap, and it is industry standard to bill the set up time across the batch of parts. e.g. If the setup cost for part is £150 and you make 10 parts, then those parts would cost £15 + the raw material + the time to machine. But if 1000 parts were made the cost would drop to £0.15 per part + the raw material + the time to machine.
Tooling cost is a large cost. We need to design and machine tooling so our CNC machines can hold the raw material securely and to allow for quick, efficient machining. Designing the tooling carefully and making many parts at one time optimises production, meaning the machine can produce more parts faster. This reduces costs considerably. Making a good size batch also means we can save on material cost by buying in bulk. It won’t be a huge saving but it all helps. By increasing the batch size and optimizing tooling for more efficient machining we can attain in excess of a 60% reduction in production costs. So in summary we need you help to make tooling for all the components, and to spend the time to programme the CNC machines to make the components in the most efficient way. With your help we can make project successful making the new engine affordable.
The Kontax Guarantee
Designed and Engineered in England
Risks and challenges
Kontax Engineering Ltd was founded in 1964 and we have been making and selling Stirling engines since 2001. We are known for producing quality engines that people adore. Customers often come back to buy another engine for themselves or a loved one. Our staff have been running e-commerce websites since 1999 and we ship worldwide on a daily basis.
Our new engine has been designed using the latest CAD software, prototyped and tested thoroughly.
We have backed many kickstarter projects ourselves and seen some falter. That’s why we have chosen to develop the project further before bringing it to kickstarter. We are ready to start production. The difficult stuff has already been achieved. Furthermore this is our 2nd in-house and 3rd overall Kickstarter project we have had involvement with.
There are 3 small risks:
DELAY SOURCING RAW MATERIAL
We have various suppliers for bearings, screws, raw material etc. Most can deliver in large quantities the next day. A couple of things require longer lead times. We have worked with all our suppliers for years. We don’t expect any delays but nonetheless it is a tangible risk so worth mentioning.
UNEXPECTED PRODUCTION DELAYS
This could be something like a machine breaking down or staff illness. We have 7 staff and 7 CNC machines. Again I think this risk is small but it is worth mentioning.
LARGER THAN EXPECTED NUMBER OF BACKERS
Sometimes kickstarter projects go crazy and surprise everyone. We produce thousands of engines a year but we do have a limits on what we can produce in given period. If the project becomes a huge success it will take longer to fulfil all the orders. But remember it is our workshop, we are in full control so we can ramp up production if needed.
Just for openness, transparency, reassurance our workshop is at Kontax Engineering Ltd, Unit 11a Waldeck House, Waldeck Road, Maidenhead, Berkshire, SL6 8BR, England. Company number is 831774. VAT Number is 302119025. The company owner, 100% shareholder and director is Glenn Turner. The company website is: http://www.stirlingengine.co.uk
We have done one other kickstarter project previously in 2015. Search under "Nano Cannon Stirling Engine". You can read the positive feedback in the comments section.Learn about accountability on Kickstarter
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