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Electric Planes

theprestige said:
How about a drone with ICE engines and wings optimized for takeoff, that clips on top of an electric airliner optimized for efficient cruising? The drone helps the airliner get off the ground in a reasonable distance at a reasonable acceleration, then detaches and circles back to the airport to pick up its next client.

Or would it be the other way around? Either way, why not that?
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That idea was suggested back around 1952 for jet airliners (as jet engines of the time had poor performance at low airspeeds). Didn't really take off back then.

Hans
 
macdoc said:
This field may be progressing faster in the real world than anticipated
[qimg]https://i.insider.com/6323422cd5916b0019abe011?width=700[/qimg]


https://www.cntraveler.com/story/bookings-open-on-sas-first-commercial-electric-plane
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Err, while I agree with some of what you have been saying here, that is not a truss-braced wing on the ES-30. It looks reminiscent of one, but it isn't.

Truss braced wings have a high aspect ratio, that is they are very long, very thin and very narrow. This results in lower drag but also lower lift. AIUI, the truss braces themselves are aerodynamic surfaces that both support the thinner wing to help with stresses in flight, as well as to help compensate for the lower lift from the wing itself.

The ES-30 you depicted does not appear to have high aspect ratio wings, so I suspect those are simply wing struts primarily for support on the ground. There is also no mention of the use of truss-braced wings in any of Heart Aerospace's documentation on the ES-30.
 
smartcooky said:
Difficult to reconcile this with the fact that the vast majority conventional aircraft known for their STOL capabilities are High-Wing designs... C-130, Pilatus Porter, Short Skyvan and the whole range of DHC STOL aircraft, the Beaver, Otter, Caribou, Buffalo, Twin Otter and Dash 7.

Of course, the primary reasons for this are that high-wing designs are more aerodynamically stable and not affected by crosswinds as much as low wing aircraft. High wing designs also have better landing performance than low wing designs for the same reason as you mention, less ground effect.
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How would ground effect actually play out on take off? You get off the ground earlier at a lower speed, and then your rolling friction is zero and you could raise your undercarriage, so your speed will rise faster.

But is that so significant?

Would it actually provide much help in clearing a the surroundings that presumably are fairly awkward if one actually needs a STOL runway? Given that presumably we're talking about more than 10 or 20 metres above the runway.
 
jimbob said:
How would ground effect actually play out on take off? You get off the ground earlier at a lower speed, and then your rolling friction is zero and you could raise your undercarriage, so your speed will rise faster.

But is that so significant?
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Its not so much significant at take-off as it is at landing. Low wing aircraft have a tendency to "float" because they enter ground effect earlier. The absolute last thing you need in a STOL aircraft landing at a short runway like Saba in the Caribbean, is an aircraft that won't get down.

At take-off, the biggest issue comes from the role STOL aircraft are made for... operating out of short, dirt or unsealed airstrips where the risk of damage from FOD is higher.
 
Mentour Now! has published a video about a small electric plane. It is normally used to train pilots. The takeoff checklist is simple. There are only four switches. It has a range of 45 minutes + reserve time.

 
Lplus said:
Yes, considering the number of flights by jet fuelled aircraft up to now and the incredibly low number of fuel tank fires. Note the the particular fire/explosion you point out was itself most probably started by an electrical fault in the fuel level sender system. Do you have any more to show?

Lithium Ion batteries do self discharge without warning and cannot be put out. It may be extremely rare, but I think it will happen more than once as more and more short range electric aircraft are put into service.
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Yes, I know that incidents like that are very rare in airliners. Do you think the FAA is going to allow a passenger aircraft to be certified for commercial use if it is a "lithium fire that will kill the passengers prior to the crash'', just waiting to happen.

Personally I don't think they will. But hey, maybe they will as part of a conspiracy to make EV planes look bad?

I have nothing else to show. Why should I? Airliners are very safe compared to driving a car on highways.

Why can't lithium batteries be made safer than jet engines and airliner fuel tanks?
 
theprestige said:
How about a drone with ICE engines and wings optimized for takeoff, that clips on top of an electric airliner optimized for efficient cruising? The drone helps the airliner get off the ground in a reasonable distance at a reasonable acceleration, then detaches and circles back to the airport to pick up its next client.

Or would it be the other way around? Either way, why not that?
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Every plane needs to be able to take off on its own, because you need to be able to abort a landing. And the inefficiency of the takeoff probably won't be worse than the inefficiency of using two vehicles to do the job of one.
 
Maybe they can be. But they haven't been yet.
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I agree. But in the 1960's jet engines had not yet been made as safe to operate as they are today.
 
Ranb said:
I agree. But in the 1960's jet engines had not yet been made as safe to operate as they are today.
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Indeed. That is why until relatively recently, airliners with only two engines were not allowed to fly trans-Atlantic routes. This was the genesis of the DC-10 and the Tri-Star (L1011)
 
Ranb said:
But hey, maybe they will as part of a conspiracy to make EV planes look bad?
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No need. It's already out there in full force (I made the mistake of reading the comments to that Mentour Now video).

"It's all over the news, lithium batteries exploding for no reason! That would never happen in a normal plane!"

TWA Flight 800
Trans World Airlines Flight 800 (TWA800) was a Boeing 747-100 that exploded and crashed into the Atlantic Ocean near East Moriches, New York on July 17, 1996...

The four-year NTSB investigation concluded with the approval of the Aircraft Accident Report on August 23, 2000, ending the most extensive, complex and costly air-disaster investigation in U.S. history at that time. The report's conclusion was that the probable cause of the accident was the explosion of flammable fuel vapors in the center fuel tank. Although it could not be determined with certainty, the likely ignition source was a short circuit... As a result of the investigation, new requirements were developed for aircraft to prevent future fuel-tank explosions.
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Category:Airliner accidents and incidents caused by in-flight fires (57 pages)
- On 25 July 2000, Air France Flight 4590, a Concorde passenger jet on an international charter flight from Paris to New York, crashed shortly after takeoff, killing all 109 people on board and four on the ground... Whilst taking off from Charles de Gaulle Airport, the aircraft ran over debris on the runway, causing a tyre to explode and disintegrate. Tyre fragments, launched upwards at great speed by the rapidly spinning wheel, violently struck the underside of the wing... causing the integral fuel tank to rupture. Large amounts of fuel leaking from the rupture ignited
- China Airlines Flight 120 was a regularly scheduled flight from Taiwan Taoyuan International Airport in Taoyuan County Taoyuan City), Taiwan to Naha Airport in Okinawa, Japan. On August 20, 2007, the Boeing 737-800 aircraft operating the flight caught fire and exploded after landing... investigators revealed that a bolt, which had come loose from the slat track, had punctured the right wing fuel tank
- On 1 January 2011, Kolavia Flight 348, a Tupolev Tu-154 on a domestic scheduled passenger flight from Surgut to Moscow, Russia, caught fire while taxiing out for take-off. Passengers were evacuated, but three were killed and 43 injured. A subsequent investigation concluded that the fire had started in an electric panel... By 10:20, the aircraft was completely ablaze, with aviation fuel leaking and spreading the flames across the apron. The fire was brought under control at around 10:40; by then, only the tail section and the outer portion of the wings had survived the blaze.
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Roger Ramjets said:
No need. It's already out there in full force (I made the mistake of reading the comments to that Mentour Now video).

"It's all over the news, lithium batteries exploding for no reason! That would never happen in a normal plane!"

TWA Flight 800

Category:Airliner accidents and incidents caused by in-flight fires (57 pages)
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Not just that, but there is a public perception that lithium batteries are the primary cause vehicle fires. Why? Because the media cover them more. If a petrol powered car catches fire, the media are not interested because its not sensational enough - but an EV fire can occupy the news cycle for a whole day and trigger debate about the safety of EV's.

When first reports were coming in of the big fire that burned down the car park at Luton Airport destroying the building and 1,500 cars, the immediate speculation from most of the British gutter media was that the cause of the fire was an EV battery. They were all over that aspect like a rash. I can imagine the naysayers already penning their in-depth reports about the safety of lithium EV batteries. The moment the truth came out, that the fire started when a diesel Range Rover caught fire, they completely lost interest in that aspect of the cause!!

The reality is that fires in cars powered by ICE's are far more prevalent than fires in EVs. US Insurance company AutoinsuranceEZ.com did some research and analysis to better understand the risk of fire in vehicles. This is what they found:

Hybrid vehicles have 3,474 fires per 100,000 cars
Petrol vehicles have 1,529 fires per 100,000 cars
Electric vehicles have 25 fires per 100,000 cars

So petrol powered cars are 61 times more likely to have a fire than an EV

Source: https://www.autoinsuranceez.com/gas-vs-electric-car-fires/
 
Ranb said:
Yes, I know that incidents like that are very rare in airliners. Do you think the FAA is going to allow a passenger aircraft to be certified for commercial use if it is a "lithium fire that will kill the passengers prior to the crash'', just waiting to happen.

Personally I don't think they will. But hey, maybe they will as part of a conspiracy to make EV planes look bad?
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Don't be silly.

I have nothing else to show. Why should I? Airliners are very safe compared to driving a car on highways.
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Yep, fuel tank fires are incredibly rare. There's not many car fires where the fuel tanks burst into flame without warning either. And remember we are talking about the fuel only, not engines or other aircraft electrics, or any other form of fire on board.

Why can't lithium batteries be made safer than jet engines and airliner fuel tanks?
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No idea, but until they are the possibility remains. (note we're still talking the fuel/power supply here, not the engines) Hopefully a battery medium which had both the energy density and weight of lithium ion (or better) wiill be found that doesn't suffer from thermal runaway.


Understand, I don't care if aircraft become battery powered. My only comment was that I pitied any passenger who was on a plane that suffered a battery fire.

Maybe the planes can be designed to eject the batteries, at least the plane can glide to the site of the crash instead of falling out of the sky when the structure fails.


And I don't give a damn how rare it is, thermal runaway of lithium ion batteries occurs, and I'm within my rights to have thought for anyone caught in such a situation in an aircraft.
 
smartcooky said:
Its not so much significant at take-off as it is at landing. Low wing aircraft have a tendency to "float" because they enter ground effect earlier. The absolute last thing you need in a STOL aircraft landing at a short runway like Saba in the Caribbean, is an aircraft that won't get down.

At take-off, the biggest issue comes from the role STOL aircraft are made for... operating out of short, dirt or unsealed airstrips where the risk of damage from FOD is higher.
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Thanks, the first paragraph is what I was thinking. On the basis that you're still very low by the time that ground effect is insignificant, so the main benefits might be from being able to reduce drag earlier by raising the undercarriage, which I guess is itself possibly problematic.
 
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Delvo said:
That price comparison for a certain trip in New Zealand is deeply strange. It normally doesn't work like that anywhere else I've heard of. It makes me curious what special circumstances apply there to make it so odd.

San Antonio to Dallas is a more typical example of how the pricing usually works. For November 7, the cheapest flight is $104, leaving earlier in the morning than most people want to. At more normal times, the price goes up to $130. The most expensive option by bus is $43. If you're willing to go late in the evening/night or early in the morning, you can get it down to $28. It's $19 by train, although I'm pretty sure that's subsidized so it doesn't necessarily show how much money is actually spent to make it happen.

The fact that flying is almost universally the most expensive option, all else being equal with no interference from arbitrary outside forces like subsidies or maybe some really weird local geographical feature I can't even think of, is built in to the physical nature of the vehicles and how they work and their infrastructure & support systems. I thought that would be perfectly obvious, given the fact that holding the vehicle up in the air is extra work that non-flying vehicles don't need to devote any energy to at all, and/or the fact that if the fastest option weren't the most expensive then it would be the only option left because then the other options could not compete. The fact that both flying and non-flying options exist demonstrates the balance between time and price.
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Vonlane is one of the best ways to travel the Houston Dallas Austin San Antonio triangle. First class seats on a bus with Wi-Fi and snacks. $100-$150 when I’ve used it.

The relevance being: small electric aircraft with comfortable seats could very well find a market in that highly traveled area. Lots of backup airports, too.
 
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jimbob said:
Thanks, the first paragraph is what I was thinking. On the basis that you're still very low by the time that ground effect is insignificant, so the main benefits might be from being able to reduce drag earlier by raising the undercarriage, which I guess is itself possibly problematic.
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Oh, you've been watching "Aerosucre" cargo flight take-offs on You Tube

 
smartcooky said:
Oh, you've been watching "Aerosucre" cargo flight take-offs on You Tube

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Arrgh, I wasn't thinking that would have been advisable in order to clear a 1m fence at the end of the runway
 
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