New electric engine improves safety of light aircraft • Hacker News Board

Re: New electric engine improves safety of light aircraft

#11

Post by pbo » Mon, Jul 06, 2015, 2:32 PM UTC

snarfy wrote: post #2

Why would there be a problem with the main engine? It seems like you should fix/redesign/etc that instead of adding another engine. It reminds me of code that catches all exceptions instead of fixing the problem so those exceptions can never happen.

Redundancy is a well-accepted (at least in aeronautics) way of providing robustness. When designing onboard systems for aircraft, it is not unusual to have a function with a higher level of design assurance which is implemented by a set of similar devices with a lesser level using a majority vote.

See multi-version dissimilar software: https://en.wikipedia.org/wiki/N-version_programming

Furthermore most modern planes are designed to be able to fly with one engine inoperative, even those which have only two engines.

Re: New electric engine improves safety of light aircraft

#12

Post by pbo » Mon, Jul 06, 2015, 2:35 PM UTC

mrfusion wrote: post #4

I wonder if you could use your propeller as a "wind turbine" when landing to recapture some energy? Of fly around in thermals and charge your battery??

That is the principle of a ram air turbine. It's a small wind turbine which can operate as a power generator while the plane is flying.

Re: New electric engine improves safety of light aircraft

#13

Post by snarfy » Mon, Jul 06, 2015, 2:38 PM UTC

snarfy wrote: post #2

Why would there be a problem with the main engine? It seems like you should fix/redesign/etc that instead of adding another engine. It reminds me of code that catches all exceptions instead of fixing the problem so those exceptions can never happen.

Thank you for the responses. This is why I appreciate HN over reddit. I get comments with my downvotes.

Re: New electric engine improves safety of light aircraft

#14

Post by markab21 » Mon, Jul 06, 2015, 2:52 PM UTC

unics wrote: post #7

Wonderful idea. I do wonder how that changes the center of gravity and how much weight is diminished for cargo but seems well worth it. When the engine goes out you generally only have 10 seconds to decide where to land. Now it seems you have many minutes to find a place. In most circumstances I'd think this is better then the parachutes for planes because you have a chance to save very expensive airplanes.

I agree that this is better than parachutes , but not because of the cost of the plane. If your engine is failing, your plane failed you and isn't worth saving. that's what insurance is for : ) the moment you pull a parachute (for example the CAPS on the cirrus , the plane is totaled anyway).

The most dangerous place to have a failure is during initial take off (low hour student pilot here). The engine kicking on would give you a chance to actually do what is nearly impossible in this circumstance, get back to the airport safely without a stall.

As I understand usually the most dangerous circumstances are the one above described, stalling on base or final approach to runway and flying from VFR (clear of clouds with visibility) into IMC poor weather conditions.

Both of those circumstances wouldn't benefit from a backup engine. : (

As other people in the threads have posted, Fuel Starvation, water condensation in the fuel, some of those situations this would definitely help, but all of those conditions are 100% preventable with proper pre-flight planning and inspections.

Re: New electric engine improves safety of light aircraft

#15

Post by scrumper » Mon, Jul 06, 2015, 2:59 PM UTC

phlo wrote: post #8

snarfy wrote: post #2

Why would there be a problem with the main engine? It seems like you should fix/redesign/etc that instead of adding another engine. It reminds me of code that catches all exceptions instead of fixing the problem so those exceptions can never happen.

Systems with moving parts undergo lots of stress. At some point, they will fail. Regular maintenance limits this; and the maintenance prescribed even for light aircraft keeps it to a minimum. Still, no system is ever 100% reliable. The typical safeguard for engine failure in light aicraft is to glide to a safe landing. Starting with basic training, you'll do so repeatedly (starting from the vicinity of a landing stri…

> After a cursory first look, this system appears to be a considerable improvement in safety while avoiding much of the complexities a true twin engine system would entail.

Right. It's a sort of asymmetric thrust, coaxial twin. Very unusual, and clever too.

Re: New electric engine improves safety of light aircraft

#16

Post by mrfusion » Mon, Jul 06, 2015, 3:05 PM UTC

Dumb question, could this combined with the power from the regular engine give you thrust greater than the weight of your plane and potentially allow vertical take off and landing (imagine the nose pointed up, And obviously you'd need special landing legs, etc)

Re: New electric engine improves safety of light aircraft

#17

Post by userbinator » Mon, Jul 06, 2015, 3:05 PM UTC

snarfy wrote: post #2

Why would there be a problem with the main engine? It seems like you should fix/redesign/etc that instead of adding another engine. It reminds me of code that catches all exceptions instead of fixing the problem so those exceptions can never happen.

Even "heavy" aircraft like commercial transport jets, which are serviced and monitored much more closely than light ones, have engine problems quite frequently; look through these, for example:

http://avherald.com/

Re: New electric engine improves safety of light aircraft

#18

Post by knodi123 » Mon, Jul 06, 2015, 3:13 PM UTC

mrfusion wrote: post #16

Dumb question, could this combined with the power from the regular engine give you thrust greater than the weight of your plane and potentially allow vertical take off and landing (imagine the nose pointed up, And obviously you'd need special landing legs, etc)

There are no dumb questions, but if you were a pilot, this would certainly be a dumb thing to try.

1. in light planes, "the weight of the plane" is a little more complicated, since fuel can increase the weight of your plane by, like, 40% or so. We're talking, like, 500 pounds of fuel on a 1600 pound plane.

2. a helicopter has a very complex mechanism to give it control based on propellor movement. an airplane trying to hover without these mechanisms would be essentially uncontrolled. it would almost certainly spin like a top.

3. this specific electric boost engine claims to add 40 horsepower. a cessna 172 has 180 horsepower. So, not a shocking improvement.

Re: New electric engine improves safety of light aircraft

#19

Post by tcas » Mon, Jul 06, 2015, 3:14 PM UTC

snarfy wrote: post #13

snarfy wrote: post #2

Why would there be a problem with the main engine? It seems like you should fix/redesign/etc that instead of adding another engine. It reminds me of code that catches all exceptions instead of fixing the problem so those exceptions can never happen.

Thank you for the responses. This is why I appreciate HN over reddit. I get comments with my downvotes.

I'm not sure why you were down voted to begin with, it's a valid question seeing how old many of GA engine designs are and how reliable modern internal combustion engines are. There's tons of advances in engine technology that isn't ported to GA aircraft for a lot of reasons, the biggest I would say is cost of FAA compliance and the insurance liability of failures. If your car engine fails on the highway you can still come to a safe stop. It's an extremely unlikely thing to happen on a modern car, but it's still possible (e.g. a cable is loose and disconnects the ECU). If your aircraft engine stops (which is also extremely unlikely, given the amount of routine maintenance it goes through to be considered airworthy) in the wrong phase of flight you're going to crash and possibly die.

Every plane you fly in commercially has at least 2 extremely reliable engines, and each one is certified to be able to handle flying the entire plane safely for an extended period of time to make it back to an airport in case of failure. The certification is called ETOPS [1], if a plane has 90 minute ETOPS certification it cannot fly more than a 90 minute flight from an airport. This appears to be a low-cost method of having a couple of minutes of safe controlled flight in case of a failure, that difference can make the difference between life and death for a GA plane.

This reddit thread has some good responses as to why Honda (who probably produces more engines in a month than Lycoming has in decades) doesn't make GA engines:

https://www.reddit.com/r/aviation/comments/1lxlco/why_doesnt...

[1] https://en.wikipedia.org/wiki/ETOPS

Re: New electric engine improves safety of light aircraft

#20

Post by mikeash » Mon, Jul 06, 2015, 3:15 PM UTC

exDM69 wrote: post #9

mrfusion wrote: post #4

I wonder if you could use your propeller as a "wind turbine" when landing to recapture some energy? Of fly around in thermals and charge your battery??

> I wonder if you could use your propeller as a "wind turbine" when landing to recapture some energy? Helicopters do this, it's called autorotation. They spin up the rotor while descending and then trade the rotational momentum for a little bit of lift to make a safe landing. It's a tricky maneuver but a part of every heli pilot's training. I doubt that it's a viable strategy for light aircraft, though. The loss of a…

Small aircraft can definitely thermal. It would require powerful and big thermals compared to what a glider needs, but such conditions do exist. A small Cessna probably has a minimum sink speed in the neighborhood of 700fpm, and thermals stronger than that do exist, and are pretty common in some places.

The problem, of course, is that it's just not reliable enough to count on.