New electric engine improves safety of light aircraft
portal.uc3m.es
portal.uc3m.es
This being an emergency only thing how does it last? If it needs a new £5000 battery every 5 years just to sit there in case I can imagine many pilots just not being able to justify it. Given the target market.
CFIT (controlled flight into terrain). Sadly common, it's how Kennedy junior died and many others.
Stall/spin. Common on take off and landing and avoidance is a huge emphasis in training.
Visual flight into instrument conditions. If untrained what often happens is the pilot will end up in a spin/spiral into the ground or doing a CFIT.
Also, running out of gas or engine failure requires the pilot to activate the backup correctly. Sounds silly, but I recall a pilot crossing the english channel with her family and forgetting to switch fuel tanks which caused a crash. Human factors is a huge part of training - so for this to be effective it needs to be drilled into the pilot's checklist on engine failure. Also this is time taken away from finding an emergency landing field and trying to restart the primary engine.
I'd say an interesting comparison is the Cirrus SR20/22 which has a parachute for the plane. It gives you a great sense of security but that particular plane is the new "doctor killer" (a name given to the V-Tail Bonanza in the past).
Curious to see how this will be seen and used by industry.
CFIT, stall/spin, and VFR into instrument conditions are all training deficiencies. This solution fixes something a pilot can't be trained to avoid, an engine failure at an inopportune time. Training can only take you as far as "glide and crash gracefully" without stalling and spinning.
Also this could easily be made to automatically activate. Many multi engine aircraft will automatically increase power on the good engine by a few percent after an engine failure.
While there are clearly situations where this device can save lives, I agree with the GP that the case needs to be made that its worth the cost and weight, and that the people peddling it haven't made that case.
Training is the best, but private pilots vary drastically in their training, skill, experience level (especially recent experience).
While I would love to see all pilots selected out of the population for their aptitude, then go through years of intense military like training followed by checkrides every 6 months, it's just not realistic in General Aviation. It's a group of people that differ wildly in their aptitude, age, skill level, that just happen to be healthy enough to pass a relatively low bar medical exam.
Training for Private Pilots in the US might not be perfect, but I don't think a "throw training at it" response is all that useful of an answer. Train what? For how many hours, and require recency of experience after how long?
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.
The next step for this electric engine would be to replace that second heavy, expensive engine every large airplane carries around...
Additionally, the full power of the two engines is only needed at takeoff. At cruise they only run at 30-40%. An electric motor with a relativly small battery would be enough to provide enough power at takeoff.
As long as the electric engine can provide a sufficient backup to get to an airport after a failure in cruise, though, that would certainly be an interesting possibility.
Even helicopters don't fall that fast.
Lets say you're cruising 5000 feet above ground. That's a mile. You're in a plane with a roughly 10:1 glide ratio so you can glide 10 miles. At a best lift speed around 60 knots that's a mile a minute. Locally the only way to be more than 10 miles away from an airport or farm field would be over a great lake. During takeoff if you climb at 1000 FPM (maybe optimistic) that takes 5 minutes which puts you 5 miles away you can always turn around and glide back. All of my engineering estimates are wrong but wrong by far less than a factor of 2. Its a very long and stressful glide down if you have an engine failure.
Most engine failures don't make the news because nobody got killed or even landed off airport.
What tends to kill people is over confidence. Well, I have a big meeting tomorrow and I can handle a little rain storm, whoops. I only have a single engine and can't be bothered to IFR so I have to run scud under the overcast whoops I'm 5 miles from shore and only 1000 feet up when the engine dies (I think this most famously killed John Denver?)
Not exactly. John Denver NTSB report: http://www.ntsb.gov/news/press-releases/Pages/NTSB_Determine...
40 hp is 30kW. Assume 100% efficient gearing and motor. Stall speed is around 80 km/hr. For 20km of powered flight, that means 0.25 hours runtime. For high performance li-ion (250 Wh/kg) that is 30kg of batteries.
Add some weight for <100% efficiency, remove some weight for the part of the 20km where you glide.
Speculation: Given the difference in motor vs batteries, either they have an extremely light weight motor technology or they are using lower density li-ion for safety. A LiFePO4 pack (130 Wh/kg) would be 60kg. They could afford to double the battery size, since that is only a 25% increase in weight. Either they have a very lightweight motor technology, or there is some magic price or weight number they are trying to squeak under.
40hp 200kg brushless motors are extremely common by comparison. Dozens of places will sell you one for a few grand.
If I'm reading correctly, the AC-35 has a peak rating of 47.78 horsepower, and weighs 43.9kg.
Presumably the 200kg motors you're looking at are not intended to be part of a moving vehicle. Those are likely intended for use in factories or shops where the weight is of little concern but durability is at a premium.
That depends entirely on how close you are to the ground when the engine goes out. If its during takeoff, you might have less than 10 seconds to decide. If its during cruise, you probably have much more than 10 seconds to decide - and of course you can continue to adjust your decision as you get closer to the ground.
It reminds me of code that catches all exceptions instead of fixing the problem so those exceptions can never happen.
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 strip, of course) and should be able to bring a plane down safely. Some (very) light planes even include a parachute system that'll bring down the plane in a manner safe for its occupants.
Speaking as a private pilot with little experience, this systems seems promising to me in two respects: In the case of a failed engine, it'll take you another 20 km or so. This can make the difference between a survivable landing in a field somewhere and a completely safe landing on the closest airstrip. Additionally, you get 40 hp or so of available power in situations where you need it, like taking off or going around after a botched landing. This could allow for shorter runways and help speed your initial climb, which is generally considered one of the most dangerous phases of flight: At that point you are both flying slow and low, and both speed and altitude are important safety aids. 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.
An electrical motor which can provide backup assistance without causing further single points of failure is a nice add-on if they can make it work (I'd be sceptical about trusting this thing without extensive testing.)
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...
Even in cases where you have everything formally defined, you could still have some axiom not holding, or a transient hardware issue - a random bit flipping in memory for instance.
Putting simply, everything fails eventually, the question is not "if" but "when".
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.
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.
Controlled prop hanging is done all the time with RC planes. Example: https://www.youtube.com/watch?v=EAtByLuzXpI
Couldn't the large area of the wings counteract the counter rotation or at decrease it to an acceptable level?
Sure, toys can do it. That's what all these commercial drones are doing. But there's an irritating inverse square law that says the power required to hover goes up shockingly fast when you start to increase the weight.
Also, there's a reason commercial airlines don't use electric engines and batteries; the power-to-weight ratio for a gasoline engine far exceeds that of an electric+battery solution.
Any plane with thrust-to-weight >1 can fly vertically, but flying vertically and taking off vertically are two entirely different things. For example, the ability to convert engine shaft horsepower to usable thrust is very poor at zero airspeed. The V-22 osprey shows that it's both possible and difficult to take off vertically with propellers.
But of course this is based on my own amateur and dated knowledge. With all the work that has gone into hybrids lately, who knows.
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 airspeed from extracting energy out of the wind stream is more dangerous than gliding. Thermals aren't powerful enough to keep a non-glider aircraft in flight as far as I know.
Large aircraft use a small windmill or a ram air turbine to keep hydraulics and electrics up in case of a loss of power, though.
The problem, of course, is that it's just not reliable enough to count on.
And i don't think these kinds of aircrafts have the wing surface etc to be floating around on thermals.
I am not aware of any plane that lands without power outside of an emergency.