Why wouldn't you want to rip out your starter motor, alternator and normal battery to replace them with this? Get some wins back with regards to weight and cabin space. I'm assuming some steady use would help keep the battery in good condition as well as ensuring it's tested and ready to go by definition.
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.
At the risk of stating the obvious, many crashes would not be affected by this:
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.
That seems like a bit of an pessimistic take on this. Isn't that like saying front impact airbags aren't very helpful in a rear end collision?
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.
Most general aviation engine failures are caused by poor fuel management. Training and discipline helps just as much with fuel management.
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.
I don't think of it as someone 'peddling' something. To me it seems like a creative solution to an actual problem.
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?
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.
Commercial airplanes have (at least) two engines because of the high risk of failure at take-off.
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.
Plenty of "commercial" aeroplanes only have one engine. The Cessna Caravan springs to mind. I run a couple of Cessna 206s for joy flights. Strictly speaking, people pay my company money for this, therefore the aircraft are "commercial."
It's not just takeoff. Often airliners cruise outside of gliding range of an airport that can handle them, and a total power failure could be catastrophic there.
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.
"When the engine goes out you generally only have 10 seconds to decide where to land."
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?)
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.
Interesting! UQM has the "PowerPhase® Select 50" which is a 30kW motor. I would say this counts as the "very lightweight motor technology" I speculated they were using because you can't get any datasheets or information or even a price for the UQM products.
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.
> When the engine goes out you generally only have 10 seconds to decide where to land.
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.
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 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.
> 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.
Fuel exhaustion, starvation, fuel contaminants such as water, catastrophic failure of components that are operating under extreme heat and stress, carburetor icing caused by high humidity, engine component icing (pressure/temp sensors on turbine planes, air induction icing on piston power planes), bird strikes. Piston and turbine aircraft engines are phenomenally reliable but all the best minds and all of the money thrown at the problem over the past 112 years have not reached a 0% failure rate. Electric motors don't have the complexities of combustion engines which would be reassuring when flying a single engine airplane over water, in bad weather, or over a populated area. I think it's an awesome idea that could add a huge margin of safety relative to the cost.
Light aircraft engines are already _very_ reliable, you'll most likely spend a career flying without ever experiencing a failure. The most popular GA motor, the Lycoming O-360, has been in production for something like 60 years, and is pretty much "debugged" as far as engines go. Still, failures do happen (most often because of user error). You can switch to turboprops, and you'll get more reliability, but higher costs. You can switch to a multi-engine plane, but again costs are higher.
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.)
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:
Your analogy misses the point that a fallback mechanism is needed in the rare cases where something unexpected happens.
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".
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.
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:
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.
RC Planes have ridiculously high power to weight ratios which are unrealistic by full scale standards. They use small bursts of near full throttle power to move air across the (oversized) flight control surfaces. Full size planes just torque roll uncontrollably when they get near zero airspeed. Although with a giant engine and propeller and some gigantic control surfaces who knows.
Thanks, makes sense for this case. I'm still wondering though, say for a purely electric plane designed for this type of VTOL from the ground up, is it workable?
Couldn't the large area of the wings counteract the counter rotation or at decrease it to an acceptable level?
> say for a purely electric plane designed for this type of VTOL from the ground up, is it workable
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.
I'd at least design a vtol aircraft with 2 props to not get the axial roll torque of the single engine aircraft.
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.
Yes. They state this in the abstract: "We maximize the capacity of the battery in generating movement with the electric engine, and we have found that we can also use the system as a hybrid for light aircraft: the pilot can activate it when she wants, adding up to 40 horsepower for take-offs or whatever is needed."
Honestly I still don't fully accept that having a second engine running on completely different fuel is a good idea for a car. A hybrid airplane seems too ridiculous to even consider, because now both engines have to be lifted up into the sky!
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.
I am not sure how practical is this idea. Just thinking of the extra weight, extra maintenance, extra complexities, extra costs. For my money, I much rather have good training and a ballistic parachute installed.
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 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.
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.
I suspect that while landing you really want the engine in "neutral" so you can at any moment kick it into full power if some issue shows up. Landing is damn close to a controlled crash.
And i don't think these kinds of aircrafts have the wing surface etc to be floating around on thermals.
Usually when landing you want something like 110% of your stall speed, which means that you're not "crashing" (by which I mean stalling). This involves some sort of engine power.
I am not aware of any plane that lands without power outside of an emergency.
Staying above stall speed in a descent does not require any power. It is extremely common to perform a "power off" landing in a small plane, and these are often not in emergency cases.
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.