
Siemens Electric Airplane Flies Us Toward the Future - Osiris30
http://cleantechnica.com/2016/07/06/siemens-electric-airplane-flies-us-toward-future/
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ZeroGravitas
The most recent episode if "fully charged" was also about a prototype electric
acrobatic plane:

[https://m.youtube.com/watch?v=Xe1g1JrRRkY](https://m.youtube.com/watch?v=Xe1g1JrRRkY)

It reminded me of Tesla's evolution, where they found a niche where they can
apply the benefits of electrics and rethink some basic elements of the
platform most notably in the double propellers.

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rebootthesystem
I've been flying electric powered high performance model airplanes (mostly F5B
class) for decades. I'd like to think the electric r/c flight industry has
been trenching this territory for quite some time. With the next 2x
improvement in battery energy density cars and possibly full scale planes are
going to make a huge leap forward.

Here's a video of F5B class R/C planes. It's hard to convey just how insanely
fast these things are. Huge power to weight ratio and very aerodynamically
efficient.

You can hear the crowd gasping at the performance they see. Also note that the
motor is only turned on for a second or less at at time. If the motor were on
longer these planes would reach 1,500 feet in 5 to 10 seconds tops.

[https://www.youtube.com/watch?v=T0z9iy2SJA0](https://www.youtube.com/watch?v=T0z9iy2SJA0)

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savrajsingh
They never said anything about batteries and efficiency, the primary
constraint holding back electric aircraft.

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msandford
Exactly, sure the motor is super light. Great. What happens when you put
enough batteries in the airplane for a ~2 hour flight? Just assume that at
cruise it's only using 1/2 of the rated power. OK, now where do we find a
260kWh battery pack light and small enough to fit in the plane? That's a full
3x of Tesla Model S battery packs.

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tgb
I'm surprised it's "nearly silent". I would have thought that the rotors, not
the engine, were the bulk of an plane's noise.

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Noseshine
Try standing next to one even at low rpm. Rotor noise becomes a factor at high
rpm, but then the engine still is noisy itself. As a private pilot, small-
aircraft engines are noisy as f... Among the reasons: No development at all
for about two decades when the small-aircraft market was down (which is why
you see so many built decades ago, then a big gap, and only in the late 1990s
new developments started to come to market). Other reason, but it's part of
the first one (due to the costs involved): being conservative. If you only
have one engine and you have a very reliable one, that's what you keep using.
Especially when the costs of developing something new and getting it approved
- and you have to repeat that in different regions with different government
agencies - are very high.

It is true though, when a propeller airplane flies overhead you get
significantly more noise when it is directly perpendicular, when you get the
most noise from the propellers.

Jet engines had a significant positive development in this area. On the small
Livermore (CA) airport I had the chance to compare two small jets, an old one
and a new one. The old one made me cover my ears. The new one - less noise
than a Cessna, quite amazing.

In this context, an anecdote, but about noise on the inside: I always thought
sitting in a glider would be quiet. It is - if you keep the little window
shut. But then the cabin heats up too much (at least flying in California). I
was very disappointed about my 1 hour in a glider.

On the other hand, sitting inside a small airplane the noise from the engine
is significant and a big reason why you really want that active noise-
cancelling headset.

I can relate to this pilot (except that if he had used a good headset he could
have had it _much_ easier): [http://www.askthepilot.com/small-plane-
misery/](http://www.askthepilot.com/small-plane-misery/)

Tip: When flying in a small piston-powered airplane, _always_ bring a good
isolating headset, or ear plugs (or even both!). The movies are lying, those
cockpits are as noisy as... I can't think of an equivalent, but it's on an
"industrial level". Noise is a major stress factor in small aircraft aviation,
as you could see from that pilot's article.

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tgb
Interesting, thanks.

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coldcode
How does the engine compare to a piston engine in terms of equivalent HP?

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Intermernet
According to this[1] it's a 350HP electric motor.

[1]: [https://youtu.be/T_9-V73nT1k](https://youtu.be/T_9-V73nT1k)

