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As this question indicates, I've been thinking recently about the environmental impact of flying (since when automated cars are the only means of ground transport, aviation will be responsible for most greenhouse emissions).

So, as an amateur, novice pilot, I would like to know which is more environmentally friendly, learning in a glider or learning in a single engine prop (Piper Tomahawk, Cessna and the like)?

At first it seems obvious, the glider doesn't have an engine while the latter does. But if we assume the launch method of the glider is tow rope, this would be powered by a single engine prop, using more fuel than it would if it wasn't towing, plus the climb is the most fuel-expensive part of the flight anyway, leading me to think there might not actually be that much difference.

Clarification on this issue would be greatly appreciated.

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    $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – Federico Aug 4 at 7:07
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    $\begingroup$ Transportation only accounts for 29% (2017, US) or 14% (2014, world) of greenhouse gas emissions. So your premise that aviation will be responsible for most emissions after cars go electric is far from the truth (perhaps you meant transportation greenhouse gas emissions in particular?). Also, remember that electric cars aren't emission-free unless they're being charged with renewable energy. $\endgroup$ – Igby Largeman Aug 5 at 3:49

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Here are some options for flying in an environmentally friendly way:

  • Use an electric trainer: Since last year the all electric trainer aircraft Pipistrel Alpha Electro has FAA certification. Assuming the batteries are charged with renewable energy, this would mean no greenhouse gas emissions at all (excluding manufacturing). It will probably still take some time until larger all electric aircraft with higher ranges are available, but Airbus has already started research.

  • Use a glider with a winch: Assuming the winch is powered by renewable energy, this would also result in no greenhouse gas emissions. While winch launches are less common in the US, this might change in the future.

If you use a glider with tow plane, it will depend on how long you can fly with the glider. Assuming good thermals you could stay in the air for quite a while, which would easily be better for the environment than a single engine prop plane. But for training (where you would presumably want many takeoffs and landings), I agree with you that the tow plane would now use more fuel because it has to drag the glider along.

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    $\begingroup$ winch launches are intense but awesome, enviromental impact is the same of a big truck stopping at an intersection. Anyway, with a 10 min tow on a good day you'll fly 6 hours so really gliders enviromental impact is low. $\endgroup$ – Caterpillaraoz Aug 2 at 14:27
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    $\begingroup$ It's not really clear that Airbus' 'hybrid' research is much more than for marketing. There's not much reason to go 'hybrid' with an airplane, like there is with cars. Airplanes don't stop and go like cars do (at least not in the air.) They just go the whole time until they land. The only real opportunity for regeneration would be braking on the ground and carrying around the extra weight to do that would far outweigh any gains. $\endgroup$ – reirab Aug 2 at 20:34
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    $\begingroup$ As an alternative to the winch launch, how about a self-launching glider with an electric motor? $\endgroup$ – Mark Aug 2 at 21:50
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    $\begingroup$ @nick012000 But they don't use that electrical power for propulsion. Hybrid means you run a prop with electric power during cruise and only use conventional propulsion for takeoff and climb, where more thrust is needed. $\endgroup$ – Bianfable Aug 4 at 15:18
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    $\begingroup$ @Cloud During my gliding training, there was extensive awareness and training about Winch launch failures and accidents and I never felt unsafe during them. $\endgroup$ – D. Clayton Aug 4 at 20:46
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By using as much simulator time as possible.

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  • $\begingroup$ Simulators aren't realistic enough to provide any sort of learning experience though.. right? (At least ones you could purchase for the home) $\endgroup$ – Cloud Aug 5 at 11:17
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    $\begingroup$ @Cloud aviation.stackexchange.com/q/738/1467 $\endgroup$ – Federico Aug 5 at 11:35
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Learnt to fly a solar powered hot air balloon

The UK's International Balloon Fiesta in Bristol is a celebration of all things hot air ballooning, but this year it's taken a big stride into the future. August 6th saw the maiden public flight of the world's first hybrid hot air balloon, which flies by heating regular air from the sun alone.Source

In theory, fly forever with no fuel costs.

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    $\begingroup$ Although the question may not be explicit I don't see how this would help OP learn to fly anything like a glider or a Cessna. $\endgroup$ – fooot Aug 2 at 18:28
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    $\begingroup$ Can't help the OP if they're not explicit. How about KSP? Or jumping off a mountain? certified to fly is a different question and none of the answers that should be here would speak to that. #clickbaittitles $\endgroup$ – Mazura Aug 2 at 21:08
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    $\begingroup$ @Mazura Or jumping off a mountain? It takes lots of traditional skydives (from some kind of powered flying machine) before you get to that point. But I agree with the statement, the question is about flying/piloting not a specific way of flying. $\endgroup$ – Andreas Aug 3 at 19:21
  • $\begingroup$ You could use the Peter Pan method: just think lovely thoughts. :) $\endgroup$ – Barmar Aug 4 at 2:09
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The answers by Bianfable are pretty good. I'd add one more option:

  • Use a powered glider. There are gliders with a small engine, electric or otherwise. Some look like propeller planes with glider wings, some have a much smaller engine and a retractable or foldable propeller. My favourite example is this one. These can take off under their own power, which is less energy-intense than even a winch start, but they can then still stay aloft without using the engine, provided the weather is suitable. I think they're probably also good for beginners as it's much easier to get out of situations where an unexpected change of wind direction prevents you from making it back to base...
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The answer is pretty simple. A foot-launched glider (paraglider, hang-glider or ultralight) launched from a hill has zero emissions from the flight itself. It doesn't get more environmentally friendly than that!

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  • $\begingroup$ You still have to transport the gliders there, and you will have very limited flight time and low chance for thermal from a hill launch. A winch at an airfield might be more effective, because the gliders are stored there and are manually pushed around the airfield. And it requires less people. Unless all of them walk there or use bicycles, it's another factor. $\endgroup$ – vsz Aug 4 at 21:22
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    $\begingroup$ Flying a hill gives you infinite flight time, limited only by the wind continuing to blow in that direction with an acceptable range of strength, and by daylight since hang-gliders aren't legal for night flying. Fair point about getting there, but that's the same for getting anywhere including going to the shops. $\endgroup$ – Graham Aug 5 at 9:39
  • $\begingroup$ @vsz - Hill launching of a paraglider in the UK usually involves walking up the hill with the glider on your back. You can soar up and down the ridge for as long as the weather permits, looking for the house thermal to get you high enough to go cross country $\endgroup$ – Dave Gremlin Aug 9 at 9:28
  • $\begingroup$ @DaveGremlin : with paragliders, sure. But if we are talking about aircraft, in the classical stick+pedals configuration, then it requires more complex transportation. $\endgroup$ – vsz Aug 9 at 10:09
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"which is more environmentally friendly, learning in a glider or learning in a single engine prop (Piper Tomahawk, Cessna and the like)?"

I think you can combine the two. Glider for learning basic stuff in the airport environment and nearby (launching however the local method is, in my area that seems to be tow plane), and then small engine (100 HP) for the longer trips where there is more navigation skills and radio work/electronics (ADS-B Out) required for the controlled airspace/tower interaction.

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  • $\begingroup$ I wanted to do this, but this answer suggested otherwise: aviation.stackexchange.com/questions/64937/… $\endgroup$ – Cloud Aug 2 at 13:51
  • $\begingroup$ I would have drawn the opposite conclusion from that. But I only have powered flight time (900 hours), and none in gliders. My home airports have both been under Class Bravo Mode C veil, so radio work/transponder has been needed for all flights. There is a glider field 12 nm west that is outside the Mode C veil, we've stopped in on occasion to have a look at the gliders and watch a towed launch or two. $\endgroup$ – CrossRoads Aug 2 at 14:15
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    $\begingroup$ I learned power flying the mid 70s but didn't take up soaring until the 90s. In hindsight it would have been beneficial to have learned gliding/soaring first. However, what I did do back then was do my private in a Cherokee 140 then immediately got checked out in an Aeronca Champ, which pretty much flies like a glider with a noisy vibratey thing in front. $\endgroup$ – John K Aug 2 at 15:07
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    $\begingroup$ Glider flying procedures are nothing like an "airport environment." Since gliders have no ability to "go around" to abort a landing attempt, and (except for motorized gliders) can't taxi on the ground, you won't learn anything equivalent to "flying circuits" in a powered aircraft at an airport, for example. $\endgroup$ – alephzero Aug 3 at 13:34
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    $\begingroup$ @Cloud Exposure. You do anything for a while successfully and the perceived risk declines. I can tell you one thing. I you give me the choice of being caught out of gliding distance of the airport in a glider, or the engine going south in my power plane in the same spot, I'll take the glider in a heartbeat. Although, if I'm over flat landable terrain, neither one is really life threatening with any reasonable level of competence. $\endgroup$ – John K Aug 5 at 14:32
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The primary source of pollution from single engine propeller airplanes is the avgas used as fuel. Avgas is typically gasoline with tetraethyllead (TEL), a lead-containing additive used to reduce engine knock. The most environmentally friendly way to learn to fly, short of using a fully electric airplane, is to use an engine which supports unleaded automotive gasoline natively, without having to resort to extremely high octane.

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  • $\begingroup$ The lead helps with knock resistance (pre-detonation) at altitude. Diesel (jet fuel) may be an option for more planes some day deltahawk.com or eps.aero Problem is retrofitting it into certified aircraft - the combination of engine and aircraft has to be certified. I thought I saw 90K to have one installed in my plane, which is somewhat more than a new avgas engine at 50K plus mechanics time to remove & put all the accessories back on and reinstall. Jet fuel around here is a lot more than avgas tho, and the airport where I'm based doesn't carry it. $\endgroup$ – CrossRoads Aug 3 at 13:21
  • $\begingroup$ DA42 (twin) and some versions of DA40 (single) natively have diesel engines and burn Jet-A. $\endgroup$ – Zeus Aug 5 at 1:17
  • $\begingroup$ While it's true that getting rid of the need for TEL would be nice, the number of light training aircraft that can run on car gas is quite small compared to those that run on avgas... and they tend to be substantially newer and, thus, significantly more expensive. It will be pretty rare to find an aircraft available to rent for flight training that runs on car gas. You can certainly by new aircraft that run on car gas, but that's probably not something you're going to want to do for primary flight training (unless maybe you're quite wealthy.) $\endgroup$ – reirab Aug 5 at 2:17
  • $\begingroup$ @reirab Most piston engines run perfectly fine on 91 octane auto fuel and there are STCs for all sorts of them. The fuel has to be alcohol free, and you have to take some measures against vapour lock (keeping fuel system cool in hot weather). My Lyc O-290 is MUCH happier on mogas than 100LL, because it is not able to scavenge the lead level and I have to clean plugs every 15-20 hours. The only benefit to leaded fuel is valve seat lubrication but newer hard metal valve seats negate this factor. $\endgroup$ – John K Aug 5 at 14:38
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Depends on your definition of "fly". If you simply mean flying a plane-like object around in they sky, the fuel spent on a glider tow might only be 5-10 minutes worth, and on a good day you can stay up practicing your technique for hours. Your up-time-to-fuel ratio can pretty low, though I can't say the environmental impact of the manufacture of the two planes involved.

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    $\begingroup$ And the ultralight with hang glider wing and little Rotax or Jabiru engines are also flying, burning measly amounts of fuel. Some even have cabins. $\endgroup$ – CrossRoads Aug 2 at 22:05
  • $\begingroup$ @CrossRoads Problem in the UK is, it's usually very windy year round, making ultralights / hang gliders not an option $\endgroup$ – Cloud Aug 5 at 11:24
  • $\begingroup$ @Cloud - In a hang glider or paraglider, the wind is your friend, up to a point :) $\endgroup$ – Dave Gremlin Aug 9 at 9:37
  • $\begingroup$ @DaveGremlin I think that point is surpassed usually here :) $\endgroup$ – Cloud Aug 9 at 9:49
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    $\begingroup$ @Cloud - I think the BHPA and the local clubs would disagree $\endgroup$ – Dave Gremlin Aug 9 at 12:04
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A significant part of the environmental cost of the airplane is building it in the first place.

That becomes relevant in a crash. A gentle crash saves the airframe, a rough crash makes you buy another airplane.

Therefore, glider training is an environmental win, because it makes you better trained to gracefully recover from an engine-out situation, giving you a good eye for less destructive off-airport landing fields, and better at managing energy to get to such a spot.

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By using flight simulator where possible.

Running the simulator is definitely more environment friendly than running even a small aircraft. A very high end computer with multiple CPUs and several video cards maybe would use 1500 W of power under full load (this is how much the most powerful PC power supplies are rated). Maybe multiple large monitors would use few hundreds more. This is next to nothing in comparison to 75000 W required for launching even a glider.

Of course, simulators can only replace part of the training but especially in cases when somebody has enough hours but for some reason not enough skills to pass the test, this could probably work.

This answer assumes certified simulators like this one for CESSNA 172, certified. I mean, not a PC running a star wars computer game with just mouse and keyboard attached.

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