OT All electric fighter plane.

Can you do basic sums? Compare the energy to acclerate a 10 tonne plane to 120 mph, with the energy required for it to climb to 30,000 feet

The electric pickup is to preserve batteries. Some energy from the batteries, some from the pickup. A lot of energy is used to get a plane in the air. If the some that can come from the ground then a plus.

The first hybrid plane was in 2013 in Germany using a rotary engine genny and batteries turning an electric prop. Rotary engines are about a third of the weight and size of a piston engine for the same power output. The concept was proven.

Rotary engine development over the past five years has pretty well eliminated its flaws, however the EV will put it into the shade for autos. Too late. Mazda are introducing one in a hybrid car next year, no direct drive. Running at a 'constant speed' turning a genny they are very efficient, so this development may be used in light planes.

Rotary engines are already used in drones.

In terms of efficiency a simple modern electric motor can't be beaten. Anything added reduces efficiency and increases weight.

The point about hybrids is the energy dense fossil portable fuel.

The point of for example diesel electric trains is to keep the ICE engine running at a constant efficent speed.

Aircraft engines spend 99% of their time at constant speed, some additionally have variable pitch propellers. So a hybrid aircraft is pointless.

The only way range will increase is with a breakthrough in battery technology.

The aircraft (if it ever comes) will be much slower that a modern jet airliner and will fly at very high altitudes. (Reduces drag and the electric motor needs no air). As it descends it's battery can be recharging.

Oh yes, until recently I had my own aircraft.

Drivel. On the ground, the aircraft is accelerated from zero to airspeed.. A miniscule part of the total energy requirement.

One great prime advantage is that hybrid planes can use only electric batteries on take off and landing (zero emissions), which invariably is over lots of people's lungs below. Batteries can be charged while in flight.

Hybrids are being worked on, even hybrid gas turbines and turbojets.

As I wrote, the electric pickup on a runway is to assist in take off when lots of energy is used. Battery preservation. It is one [point being looked at.

Until recently I flew in a plane. It was very big.

No, a lot of energy is used to get a plane up to cruising height. Compared with that, leaving the ground is peanuts

I advised people to do the sums, but it seems that you too prefer to Believe than Calculate.

Poor old John. I have been flying electric planes and doing the sums for nearly 20 years.

I have at least 15 electric aircraft. I designed them all myself.

Hmm. With hybrid vehicles, the big savings come about when power demand is small. At a constant cruising speed they appear to offer few savings over a vehicle that is directly driven, assuming like for like.

And surely on a plane the majority of its travel is at a cruise?

Perhaps this one, at 208 feet wingspan.

Paul

Hydrogen fuel cells are also being looked at for planes, with electric motors turning fans. In modern bypass turbofan 85% of the thrust is via the fan turning (moving air backwards). Hydrogen fuel cell planes look promising.

Soar panels as an integral part of the wings and fuselage, are being looked at for obvious reasons.

not a lot of use for overnight flights ;-)

I guess they could be used to recharge a couple of passengers mobile phones.

A little knowledge, dear John, is a dangerous thing. Just knowing that stuff happens 'because', is the easy part of science for the sub 11 year olds.Learning *how much* of it happens, needs Doing Sums, something your generation appears to think isn't necessary to call yourselves intelligent and knowledgeable.

The frightening thing is that you almost certainly have a vote. And will use it to support whichever shyster paints the most glowing picture of your future, whilst delivering you to a life of effective slavery and ignorance.

You may be a useful idiot to them, but to the rest of us you are beyond useless.

Not a lot of use for daytime flights either.

A little lesson in applied mathematics.

The amount of power needed to cruise a plane is pretty simple if you know its glide angle and its weight and its cruise speed.

For an A320, the glide angle is about 1:17. Lets be generous and make our plane 1:20. The wing area will be around 300 square meters, The weight will be around 150 metric tonnes all up loaded. It cruises at 600km/h.

Simple vector analysis shows that with a lift to drag ratio of about 20 (the glide angle) the drag will be 7.5 tonnes force. in SI units multiply that by 9.8 (g) to get SI units - say ten, so that 75, and that times the speed in meters per second is the watts needed to fly it.

Now we know that the wing area is 300 square meters and a solar panel is doing well in sunlight that is falling directly on it at 1kw/sq meter. So 300kW.

The weight of the solar panels alone would make that not a cost effective addition.

But 'Dear John' BELIEVES in fairy tales told to him by skilled marketing creatives whose education matches his own in technical incompetence. Surely with enough money spent we could get 12MW of solar power out of a

Not if the energy doesn't fall on it in the first place.

Lets look at the next fairy take. Catapult assisted take offs. Despite the fact that no one uses them already except to get of extremely short strips like an aircraft carrier..

Let's say our 150 tonne plane needs to climb to a cruising altitude of

Now let's look at the energy to get the plane up to a 200km/h flying speed, which is what the catapult does. that's about 55 meters per second, so using E=1/2mV^2 the kinetic energy is about 230MJ

So at best it merely adds 20% to range. Except in the end where the real fuel burn is is in that cruise.

Let's go back to the cruise, and let's say we want to travel 1000km

The drag times the distance is the energy used. and we have 75,000 (kg) x 10 (1g) x 1 million (meters).

So lets put this in perspective. To get it off the ground takes 0.23GJ To get it up to cruising altitude takes 1.5GJ To get it to where its going takes 750GJ. At an average burn rate of

A catapult launch is completely meaningless. And any solar input will add more weight than the extra drag it produces dies to plane weight increase

One final look at the sorts of energy required: 750GJ is 200MWhr plus minus.

A typical lithium ion battery is about 150Whr per kg. or 150KWhr per tonne. Which puts the average EV battery (50-100Kwh) in the 1/3rd tonne to 2/3rd tonne range.

So our plane would require a Li-Ion battery of around 1000 tonnes to fly it 1000km. With no margin for error. But its already a 150 tonne plane..would it ever get off the ground?

Those are in a nutshell, the mathematics surrounding electric flight.

I've been designing calculating and building battery electric planes for nearly 20 years. The numbers here stack up. Mere development won't make it happen, it needs a total breakthrough in energy storage.,

Of at least 10:1 better energy to weight ratio on existing batteries.

In the end when you knock the equations about what drops out is: Forget catapults - energy gai is irrelevant Forget solar panels on the wings- energy gain is pointless You need a battery with ten times the energy density - something like a MWh/tonne or better.

Only Lithium air even comes close and the problems of making a lithium air battery are almost as hard as making a fusion reactor.

BUT that is the only way commercial long haul electric flight can be achieved with electric motors.

All other development paths are simply wasting someone else's money. That doesn't preclude a breakthrough at the quantum level of course and a non-chemical energy secondary battery, but there is nothing on the horizon there at the moment.

All the other bits - high efficiency motors, good blade and inlet ducted fan design and so one - are sitting there waiting. A supersonic electric plane would be possible with the right battery....

Love it!

Don'tcha just love it when greenie fantasies are hit by the reality of the numbers!

Yebbut, those numbers have *not* included the team of pigs harnessed to the nose...