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I have seen that there are many companies working toward hybrid electric aircraft. It is very exciting some of the ideas.

The primary reason seems to be for limiting CO2 emissions acceleration, especially during take off. In theme parks acceleration is often performed by powerful magnetic forces.

I was wondering if in the long run a powerful electro-magnetic system could pull planes, fitted into a track on runways for take off?

Jamiec
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KILLBOT_PRIME
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    The takeoff only accounts for a fraction of the fuel usage of an average flight. I doubt limiting CO2 emissions specifically during takeoff is the primary reason for developing hybrid planes. – 60levelchange Oct 21 '20 at 07:15
  • See also https://aviation.stackexchange.com/questions/31048/ and https://aviation.stackexchange.com/questions/77749/ – CSM Oct 21 '20 at 10:21
  • @expeditedescent the thing to keep in mind is that when a system is extremely optimized for efficiency, it can reach the point where a non-trivial part of the overall consumption/emissions come from one brief mode where it has to operate far less efficiently. So you see attention to even things like taxing around, and hotel loads while waiting for a slot. Also ground and near-ground operations create a localized concentration of emissions. – Chris Stratton Oct 21 '20 at 16:40

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Catapults are used to launch airplanes on aircraft carriers, most are currently steam powered but the US Navy are developing an electronic catapult system called EMALS to replace steam ones in the future. Other countries are developing the same technology. The US Navy system has been shipboard tested, apparently there are still some problems but they will likely get worked out, so the technology is viable - it is possible.

Shipboard catapults are used to accelerate airplanes quickly in the very short distance you have on an aircraft carrier deck, not to save energy or fuel. It doesn't make practical or economic sense to use the technology to accelerate airplanes in a normal airfield for the following reasons:

  • It's very expensive technology to buy and maintain. It would cost enormous amounts of energy to deploy this technology
  • It will limit airplane operations to those airfields which have the technology. I can fly a Cessna 172 into and out of remote strips, but if I require a catapult of some kind my options become very limited
  • It doesn't actually help much. It's not the take-off roll which is energy intensive, it's the climb to altitude, and a catapult wouldn't help with that. When you think about it the take-off roll is a minute, climbing to altitude is 20 minutes in a commercial jet, you'd be reducing the energy needed by at most 5%, which isn't worth the investment
GdD
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    The engines would still be running, and probably at climb power, during the "cat shot," so you're only saving fuel by *reducing* the time spent getting from 0 to flying speed - some of the 'on the runway' fuel burn still happens. – Ralph J Oct 21 '20 at 14:44
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    That's got me wondering about using TGV locos for a 200 knot 10000 feet version of a glider tow! – user_1818839 Oct 21 '20 at 15:49
  • I'm sure passengers would love that experience @BrianDrummond – GdD Oct 21 '20 at 16:20
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    @Brian Drummond: Why think small? Use a rail gun: https://en.wikipedia.org/wiki/Railgun – jamesqf Oct 21 '20 at 16:40
  • I don't think we want to turn the passengers to sludge @jamesqf – GdD Oct 21 '20 at 16:55
  • An important consideration with catapult launches is that they're used to reduce required runway length. To use a catapult, one would either have to have enough runway to allow a plane to safely stop if after being catapulted it would be unable to develop enough power to get and remain airborne, or else accept the fact that the plane will go off the end of the runway in such cases. If a carrier-launched jet is unable to climb after catapulting, the pilot can eject and let the plane fall into the ocean, but such a contingency plan would be unacceptable in civil aviation contexts. – supercat Oct 21 '20 at 17:42