No loophole nor exceptions - we're following guidance from the International Maritime Organization on the maritime regulation of Type A WIGs (https://wwwcdn.imo.org/localresources/en/OurWork/Safety/Docu...), which have been upheld by flag states all around the world.
The benefit of ground effects are:
- 10-20% range extension (agreed, between 50% and 100% wingspan, which is where seagliders fly, the aerodynamic benefit of ground effect is reduced compared to near surface flight)
- Drastic reduction in reserve fuel. This is a key limitation of electric aircraft because they need to sustain powered flight to another airport in the event of an emergency. We can always land on the water, therefore, we can count all of our batteries towards "mission useable"
These two effects combine to give seagliders double the range of any electric aircraft - 180 miles with existing battery technology.
We use hydrofoils to solve for the wave tolerance and maneuverability problems that plagued past WIGs and made them commercially unviable. To take-off directly from hydrofoils before they cavitate, we had to slow take-off speed to ~50 mph, which drove us to a "blown wing" design that distributes propulsion over the wing, "blowing" the wing with high speed air and therefore creating high lift even at low speeds.
Very difficult to distribute propulsion with IC engines or mechanical linkages. Electric propulsion technology unlocks the blown wing, which unlocks the use of hydrofoils, which unlocks wave tolerance and therefore operations of WIGs, which unlocks longer range of electric flight. It all works together.
And electrification is generally good: both for the planet and for ticket prices
Doesn't the landing make a huge impact/force on the foils? I would think that they are designed to make the craft go up, thus more susceptible to it going down at higher speed?
Both landing and take off should be akin in terms of force encountered by the foil unless you're landing over speed or with the craft at an angle respective to your trajectory or the water current. The foils look motorized which is likely the biggest concern compared to static foil designs.
With today's tech you're spot on. As batteries advance though, we expect ranges closer to 500 miles by the end of the decade, which would indeed enable SF<>LA!
3x increase in battery capacity in the next 7 years seems rather optimistic to me. Are there any specific battery advancements in the development pipeline that you know of?
How are you managing battery degradation, especially given that you're planning for high charge rates with quick turnaround? Do you have an idea of how many pack replacements you'll need over the lifetime of the rest of the aircraft?
IIRC, a lot of the energy use in a plane flight is due to the initial acceleration. So double the capacity is more than double the distance. You can also just use a bigger battery when the weight efficiency is better.
Amprius is planning to offer a silicon nanowire anode sometime in the next decade it seems, which probably won't double the capacity, but it would be a significant improvement.
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"I would love to tell you that my first job was working under my Uncle Ros (https://en.wikipedia.org/wiki/Rostislav_Alexeyev) as we meticulously broke down and redesigned his life's work from the ground up, but unfortunately that's not true" - Coby Fleener
Anywhere near significant boat traffic (e.g. in harbors), we'll be on our hydrofoils at speeds of 20-50 mph. So in these environments, we're just another boat (albeit a very comfortable, wave tolerant one)
We dont leave the foil to takeoff onto our wings until we leave the harbor. This doesnt need to happen on "runways" though. We'll already be at takeoff speed (~50mph) as we're leaving the harbor, so we really just jump out of the water whenever we choose to. This way we dont need to clear long stretches of water for a "runway", which has limited seaplane operations.
Absolutely agree: Seaglider operators will have to obey the rules of the road to avoid collisions just like any other boat. WIGs are actually already in the COLREGS (we're last in line for right of way, but on the list!), and our sensor systems will ensure that seaglider captains have excellent situational awareness.
That's what distinguishes seagliders from a GEV! We read the wikipedia article before setting off on this path too ;)
Seagliders are different from all GEVs (aka WIGs) and seaplanes of the past because of our hydrofoils. They lift us out of the water on stilts giving us 5ft of wave tolerance. We accelerate to takeoff speed on the foils (which lets us point into the wind even through waves) and then takeoff onto the wing and settle into ground effect.
Yes we'll have several sensor systems onboard that augments the captains visual perception, including radar, AIS, and we're looking into computer vision systems as well.
We've been testing these sensor suites in helicopters today. Flying <50 ft off the water at speeds in excess of 100 mph, simulating the seaglider operating conditions. We have plenty of time to detect and avoid traffic even in crowded waterways at speed.
We looked into this! If you want to go regional range, you really need high speed rail (who's trying to sit on a train that goes slower than cars on the highway...)
High speed rail is prohibitively expensive. Besides the rail itself, you need to do grade separation from the ground so the rail can be flat, environmental impact studies, and in the US where private property rights are very strong, you might need to pay the land owners.
Look at the proposed price tags of the past 4 high speed rail projects in the US (none came to fruition):
- California High Speed Rail: $77B
- Acela High Speed Rail (NE Corridor): $150B
- Texas Central: $20B
- Virgin Trains Florida High Speed Rail: $4B (just Orlando to West Palm!)
I wish it was as simple as electric trains! Would save us a lot of engineering...
To complement this, the Acela has a top speed of 150 mph; it can only travel that fast for ~10% of the distance between Boston and DC though [1]. It fastest leg from NYC to DC averages 82mph (about as fast as driving on 95 at night ;) )
Previous ground effect craft absolutely were killed by their poor wave tolerance. That's where our hydrofoils come in. 5ft of wave tolerance through the harbors and in takeoff and landing. Means we can operate with very high confidence and high utilization in most markets.
You mentioned not needing reserve energy because you're able to land anywhere along the flight path. Does that mean you can safely land and float in waves higher than 5ft, even if it isn't necessarily pleasant for passengers or good for the vehicle?
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