How about a radial solenoid motor for an aircraft?

[old man emu]

Here's a red herring for people who want to discuss the development of electric motors as power plants for aircraft.

 

We normally think of electric motors for aircraft as being basically the same as electric motors we use everywhere.The fundamental purpose of the vast majority of the world's electric motors is to electromagnetically induce relative movement in an air gap between a stator and rotor to produce useful torque or linear force.

 

 

 

 

 The moving part is the rotor, which turns the shaft to deliver the mechanical power. The rotor has conductors laid into it that carry currents, which interact with the magnetic field of the stator to generate the forces that turn the shaft. The stator is the stationary part of the motor's electromagnetic circuit and usually consists of either windings or permanent magnets. It is also the part that adds the most  to the overall weight of the motor.

 

There is another electronic device which relies on windings to perform its function. A solenoid is a coil whose length is substantially greater than its diameter. The coil can be arranged to produce a uniform magnetic field in a volume of space when an electric current is passed through it. In practice, solenoids are used to create linear movement in an iron rod. When the rod is connected to some other device, it can operated the device as mentioned in this image.

 

 

 

 

We are used to using solenoids for one action at a time, eg throwing in the Bendix spring on a starter motor, or operating the door locks on our cars. But what if a number of solenoids were grouped together to operate sequentially?

 

First of all, lets look at how a single solenoid can be used to convert linear motion to circular motion. (Please bear with the Germanic accent)

 

 

 

 

 

 

 

 

 

 

 

 

 

[spacesailor]

Can, I run it with Piezo electricity ?.

 

 spacesailor

 

 

[pmccarthy]

Surely defeats the primary advantage of rotary motion.

 

 

[onetrack]

OME - the idea is sound, but I believe the bearings on the crank arms need pressurised lubrication, for long-term durability and substantial power output.

 

My 1977 Engel portable fridge/freezer is still running well after 42 years of fairly steady work - and it's powered by a solenoid motor (Sawafuji Swing Motor).

 

But the Sawafuji has no crank arms, no rotating parts, and only one moving part - the piston.

 

Maybe multiple Sawafuji motors could be combined to produce compressed air, which could then be used to propel the aircraft?

 

 

[rotax618]

I don’t think that a solenoid engine would be as efficient as a brushless outrunner electric motor. What is worth thinking about would be a conventional radial IC engine with solenoid operated valves. Aero engines using direct drive don’t have to be high revvers, and solenoid operated valves would eliminate all of the gears, cams, rockers and springs, saving lots of weight and complexity. A radial, because of its single throw crank could make the lightest engine.

 

 

[turboplanner]

There's nothing wrong with a Chitty Chitty Bang Bang, but I'd rather have this:  

 

 

 

 

[Yenn]

All the disadvantages of an ic engine and electric combined.

 

 

[rotax618]

I agree that electric is the future, as soon as someone develops a better battery, alas IC engines in aviation will still be with us for a while yet. You could say that a hybrid also has all of the disadvantages of IC and electric.

 

 

[rotax618]

When I replied, I had a simple 3 cylinder radial replacement for the rotax 503 class in mind, the engine could be built extremely lightweight using nikasil cylinders, CNC’d crankcase and computer controlled injection, ignition and solenoid valves. Provided it had enough displacement to provide 50-60hp using direct drive it would be possibly lighter than the 2 stroke.

 

Just a thought!

 

 

[Marty_d]

OME, your original post says that the stator windings are the heaviest part of the standard electric motor.

 

It's all relative though.  Even with that "heavy" part, the actual electric motor used in a Pipistrel Alpha Electro weighs a whopping 11kg.

 

I'd take that to get rid of moving parts!

 

 

[facthunter]

Radials require heavy flywheel mass and the more cylinders, the smoother they run. They are also BIG in frontal area relatively.. Nev

 

 

[old man emu]

Radials require heavy flywheel mass and the more cylinders, the smoother they run. They are also BIG in frontal area relatively.. Nev

 

Question: Doesn't the propeller provide the inertial mass that a a flywheel does in, say a car engine?

 

And I've already thought of calling a propeller a "fly wheel".

 

 

[facthunter]

The flywheel in a radial has to BALANCE a LOT of things, not just provide flywheel effect (which the prop can do).. There are NO opposing pistons in a radial, for mechanical balance purposes unless it's twin row and then there's a large OFFSET to contend with, with that arrangement and it needs TWO large bobweights and they have to be dynamic. Move in slots to damp torsional effects. Nev

 

 

[facthunter]

 In a ROTARY (radial) the crank is not moving and all the cylinders and conrods rotate about a fixed crankpin so no balance weight is needed. Those engines can be quite light in weight  but not particularly high revving, so high torque but not high, horsepower. Nev

 

 

[turboplanner]

 In a ROTARY (radial) the crank is not moving and all the cylinders and conrods rotate about a fixed crankpin so no balance weight is needed. Those engines can be quite light in weight  but not particularly high revving, so high torque but not high, horsepower. Nev

 

How would you feed the electrical power to the rotating solenoids?

 

 

[spacesailor]

Slip rings 

 

spacesailor

 

 

[facthunter]

I'm not envisaging using solenoids. I'm referring to existing and older internal combustion principles and internal structures. You can get high torque and light electric motors that fit in a conventional wheel  Modern electric motors are as efficient as the best transformers They should have been used to replace mechanical transmissions and driveshafts years ago. More reliability, less cost, less maintenance Nev

 

 

[mnewbery]

They should have been used to replace mechanical transmissions and driveshafts years ago

 

... and were, in locomotives

 

 

[turboplanner]

I'm not envisaging using solenoids. I'm referring to existing and older internal combustion principles and internal structures. You can get high torque and light electric motors that fit in a conventional wheel  Modern electric motors are as efficient as the best transformers They should have been used to replace mechanical transmissions and driveshafts years ago. More reliability, less cost, less maintenance Nev

 

We're talking about solenoids; have a look at post #1

 

 

[facthunter]

RADIALs, solenoids, Motors ,aircraft, so we got onto aspects of Radials particularly balance/weight considerations. One can make a point that solenoids have no efficiency advantage or are you setting all the rules? Nev

 

 

[mnewbery]

In university I cared a lot more about this than I do now. We had this new thing called "high temperature superconductivity" or just HTS. It was "new" then. The most well documented of these was BSCCO which was so easy to make, its production in a domestic oven became part of a few high school curricula. BSCCO and YBCO are still being studied today. High temperature here means "warmer than liquid nitrogen at sea level".

 

BSSCO is made from exceptionally toxic ingredients. That being said one of my lecturers designed a machine that could spit out finished material like a slow firing machine gun. The manufacturing process had no practical application. 

 

(By now you know where this is heading...)

 

The heating loss from the laminated cores in the transformer(s) or similar losses in heating the wires plus the hysteresis place limits on the power density and packaging. Spot heating is quite common and its a black art to overcome effects which seem quite random until a sufficiently detailed computer simulation can provide some explanation. Magnetic field leakage is also an issue with high power applications

 

A solenoid is a transformer with only one winding and some choice of core (movable, "air", fixed)...

 

A superconducting solenoid will typically consume 1/5 the power for the same field strength as a traditional solenoid, at scales around 200Kw. For reference the Warp 11 DC electric motor produces 58 Hp and weighs 100 Kg. The Siemens SP260D weighs 58 Kg and produces 350 Hp at a conservative 20x the price ($3k vs $60k)

 

Now imagine an electric motor weighing 100 Kg capable of producing 1500 Hp (300 Hp x 5). This would be possible using superconducting magnets - probably solenoids. A lot of liquid nitrogen would be required too.

 

So between the rare earth magnets, the toxic superconductor ingredients, the unproven packaging and the sheer inconvenience of getting LN2 ... oops forgot to mention this all runs on batteries and a starting price around $1M  (have a look at used MRI prices).

 

I think I'll stick to 100 low lead 

 

 

[turboplanner]

This looks very promising, like battery powered cars, costs will come down in time. I've got a photo somewhere of a train with a superconducting motor from about 1986, but I think it's still out there in the ether waiting ..............you never know.

 

 

[old man emu]

Solenoid operated valves in an conventional internal combustion engine sounds like a good idea for weight reduction and accuracy of timing. Aren't fuel injectors some sort of solenoid?

 

Radial and rotary engines are Drag generators and the rotary affects the ability to turn in one direction.

 

As soon as a very, very efficient way to remove the maximum number of electrons from a chemical element or compound, then electric motors, which don't suffer the effects of diminishing atmospheric oxygen concentrations with altitude, will become the norm for light aircraft propulsion.

 

Now, here's a side-tracking issue. If, in the future, electric motors become the norm in light aircraft and power units are made for quick interchange (like rechargeable power units in tools) would the removal of a spent unit and its replacement by a fully charged one constitute "changing an aircraft component" and would have to be done by a licensed engineer?

 

 

[Marty_d]

Are you saying that adding fuel to a plane is currently "changing an aircraft component"?

 

I reckon the rule will become the same for batteries.  Plug and play.  If you don't push it in until it locks, the plane won't go, so I can't see any problem with the mechanically-challenged doing it.

 

 

[facthunter]

Just a canon plug and a clip sort of thing. Surely we can make things self checking. It's not too hard to do. You can easily design something that will only fit one clear way if you make the effort.. If not, Murphy's law will always come into play.. Nev