Engineering vs Design

[james_s]

Rotary engines are not 'more efficient' than reciprocating internal combustion engines.  They have a higher surface area to volume ratio, so a fundamentally lower overall thermal efficiency, and cannot easily leverage variable valve control and as a result again, cannot be as fully optimised as well as a typical poppet valve system.

And of course, intake and exhaust valves do not "crash" shut or open.  In fact, the losses is a typical mechanically operated poppet valve system are extremely low, just a small amount of friction and the tiny hysteresis of the valve spring. (The energy stored in the spring is returned to the camshaft on the closing flank )

There are different ways to define efficiency. Due largely to the fact that Wankel engines are essentially two-stroke, with a power stroke on every revolution of the crankshaft, have a high *volumetric* efficiency, in other words they produce a lot of power for a given displacement and physical size of the engine. They also produce a lot of power for the weight of the engine, those are both valid measures of efficiency, yet completely different from the fuel efficiency, mechanical energy extracted per unit of fuel consumed. That is arguably the most important measure of efficiency for a car engine, and that is one area where the efficiency of a Wankel engine has been mediocre at best.

Piston engines are not all that bad really, after more than a century of refinement they are dependable and reliable, fuel efficiency is quite good compared to other known methods of extracting mechanical energy out of combustible fuel. It's not unusual for a car engine to go 300,000 miles or more with little trouble so long as you keep oil in it. I don't foresee any further revolutionary improvements in the internal combustion engine of any type, just gradual evolution.

[Cerebus]

Internal combustion Piston Engine - poor design.  Good piston engines are examples of great engineering overcoming the fault of the engine design.

Rotatory Engine is a much better design.  More efficient, much fewer moving parts...etc, etc, etc.

What? That is entirely opinion and mostly incorrect. I've edited your post for accuracy below:

Good piston engines are examples of great engineering

A piston engine is not a design of engine, it is a type of engine and is not an inherently poor "design".

As an example, the BMW S54B32 is a particular design of a type of engine. The engineering is the effort put into fine detail of that particular design in order to make it meet its performance goals.

What a load of utter - if Wankel engines are "superior to piston engines" because they are more efficient and have fewer moving parts, then since turbine engines are more efficient  and have even fewer moving parts than Wankel engines (they have one moving parts) I can only conclude that Wankel engines are poor, faulty designs. Convenient that I have come to that conclusion as I completely agree!

I think here we have a classic example of one difference between designers and engineers. A designer will understand that an illustrative example is just that, and will try to draw from it. An engineer will pick apart the minutiae of why your example is wrong, often at length. 

[Cerebus]

Anyone can do design, engineering is minimising cost/material, or maximizing the output of an already existing widget using knowledge and tools available to you.

Sadly no, not "anyone" can do design. You only have to look at the many, many examples of badly designed things that we all encounter on a daily basis to realize that good design is rare, and good design ability is a rare skill.

[Smokey]

I love that a big chunk of this thread is talking about engines.

Like it has been said above, a general definition is hard.  But specific examples are pretty easy.

I hear stories about a former non-engineer CAD designer at another company who got too much mechanical engineering responsibilities.  The stuff he made typically was initially the right size and shape mechanically, but there were always problems like not getting the materials correct for the environment or not understanding how things would wear over time.  The stuff he made was never reliable or robust.  These are mistakes a good mechanical engineer would be expected not to make.  I think that's the best example I got.
My shot at a general definition I guess would be: The engineer gets to work out all the details that are critical for the thing to work right, and the designer gets to put the rest of the thing together based on the rules the engineer laid out for him. 

Or if you work at a small company then you get to be the engineer, designer, plumber, receptionist, etc.

[Rick Law]

...
snipped away the discussion about engine details
...

I think here we have a classic example of one difference between designers and engineers. A designer will understand that an illustrative example is just that, and will try to draw from it. An engineer will pick apart the minutiae of why your example is wrong, often at length. 

Thanks for saying that.

I was getting frustrated about the discussion of the details to the point I regret having selected engine design as an example - or my failure in explicitly saying whichever engine is better (or not) doesn't matter - the purpose was to highlight the design of the engine verses the engineering of that design.

We are all trained to do certain things.

This reminds me of an observation made by someone: "If you point at something with your finger, most people will look at what you are pointing at.  But, a dermatologist will just look at the skin of your hand and finger."

[james_s]

This reminds me of an observation made by someone: "If you point at something with your finger, most people will look at what you are pointing at.  But, a dermatologist will just look at the skin of your hand and finger."

So will a cat, in most cases.

[tggzzz]

I love that a big chunk of this thread is talking about engines.

Like it has been said above, a general definition is hard.  But specific examples are pretty easy.

I hear stories about a former non-engineer CAD designer at another company who got too much mechanical engineering responsibilities.  The stuff he made typically was initially the right size and shape mechanically, but there were always problems like not getting the materials correct for the environment or not understanding how things would wear over time.  The stuff he made was never reliable or robust.  These are mistakes a good mechanical engineer would be expected not to make.  I think that's the best example I got.

That's a good instantiation of the point made by the engineering professor.

My shot at a general definition I guess would be: The engineer gets to work out all the details that are critical for the thing to work right, and the designer gets to put the rest of the thing together based on the rules the engineer laid out for him. 

The engineer gets it to work, the designer makes it look pretty and (optionally) be easy to use.

[frozenfrogz]

The engineer gets it to work, the designer makes it look pretty and (optionally) be easy to use.

As a product designer I need to strongly oppose that!

Ease of use and looks are just two of the various parameters you need to look into as a designer. To tell you the truth, I am not happy with the term "designer" in general, because it is so fuzzy. Even if you ask two designers on what a designer does, you will be left with at least three valid, but different answers
There is inflationary use of the word in everyday speech also, what adds to the problem of clearly defining it.

My main job is to listen to everyone on the table in any project stage. The designer needs to be aware of everything that is connected to the product to be able to figure out the best way to get things going in the right direction. In order to truely be a link between the different departments the designer needs to have a deep understanding of what everyone does and is good at doing. Also it helps a lot if you can speak all the different languages. You need an understanding of how everything works from marketing and sales through part sourcing and all of the supply chain, engineering, manufacturing, after market and customer relations...
At one point you might be the one that needs to bring it all together in a product, so it is best you also technically understand what works and what does not. Of course you do not need to draw every part on your own, that is why you usually work together in a team with everyone on the table.

But then again there are a lot of different positions for a designer to work in. You might be an a technical engineer, an illustrator, a project manager, the guy with the weired ideas from r&d, the company's universal translator, an input buffer, or something totally different...

I hope you get my point

[tggzzz]

The engineer gets it to work, the designer makes it look pretty and (optionally) be easy to use.

As a product designer I need to strongly oppose that!

Ease of use and looks are just two of the various parameters you need to look into as a designer. To tell you the truth, I am not happy with the term "designer" in general, because it is so fuzzy. Even if you ask two designers on what a designer does, you will be left with at least three valid, but different answers
There is inflationary use of the word in everyday speech also, what adds to the problem of clearly defining it.

My main job is to listen to everyone on the table in any project stage. The designer needs to be aware of everything that is connected to the product to be able to figure out the best way to get things going in the right direction. In order to truely be a link between the different departments the designer needs to have a deep understanding of what everyone does and is good at doing. Also it helps a lot if you can speak all the different languages. You need an understanding of how everything works from marketing and sales through part sourcing and all of the supply chain, engineering, manufacturing, after market and customer relations...
At one point you might be the one that needs to bring it all together in a product, so it is best you also technically understand what works and what does not. Of course you do not need to draw every part on your own, that is why you usually work together in a team with everyone on the table.

But then again there are a lot of different positions for a designer to work in. You might be an a technical engineer, an illustrator, a project manager, the guy with the weired ideas from r&d, the company's universal translator, an input buffer, or something totally different...

I hope you get my point

In which case there is no difference between a designer and an engineer - since engineers have to do all that too!

My list was of the minimum essential distinction between the two disciplines. That designer and engineers frequently and beneficially take on more roles merely clouds the issue in question.

[vealmike]

The public seem to think that the guys who install your satellite dish, repair your washing machine, change the oil in your car are all engineers.
They are not (or at least they are not working as engineers.)

There are two types of engineer. The first designs stuff, using complex mathematics, systems and applied physics to solve problems. The second drives a steam train.
All the others are installers, spanners or repairmen.

Because of this common confusion, many engineers amend their job description from "Engineer" to "Design engineer".

Design can be practised without engineering (eg graphic design) but engineering can not be practised without design.

[tszaboo]

The public seem to think that the guys who install your satellite dish, repair your washing machine, change the oil in your car are all engineers.
They are not (or at least they are not working as engineers.)

There are two types of engineer. The first designs stuff, using complex mathematics, systems and applied physics to solve problems. The second drives a steam train.
All the others are installers, spanners or repairmen.

Because of this common confusion, many engineers amend their job description from "Engineer" to "Design engineer".

Design can be practised without engineering (eg graphic design) but engineering can not be practised without design.

Yes, nowadays even handymen calls themselves engineers.
To the original topic: I tell girls that I am an electronics designer, because than I dont sound as a big nerd and they dont leave me immediately. When design is mentioned, then people associate that with with rounded rectangles and pencils on a drawing board.