> The startup’s most pertinent problem is creating the autonomous stabilization technologies that will make flying the Speeder effortless and safe.
looks like a smokescreen for marketing to the tech crowd. Everyone is going to believe they can solve the stabilisation problem: that's "just software" and we see demos of robots solving stabilisation problems all the time. Building a jet engine that's an order of magnitude better (cheaper, more reliable) than the industry has managed in 50 years, but with more or less the same tech? That's the kind of problem you can't just solve with machine learning.
OTOH... In the context of a moonshot, maybe the non-existence of an affordable & appropriate engine is ok. Tesla started with an unaffordable battery, and built a really expensive car with it. The car was good though, compared to other cars in the sheiks & princes price range. It was an important step on the way and proved that the real pertinent problem was affordable batteries. Not an easy problem, but still.
There's probably some demand for flying motorcycles, even if they cost >€1m and are only good for 10 minutes of hovering over a lake.
From there... who knows. I'm not sure flying cars a mass market idea even if they cost the same as rolling ones.
I'm not sure if you're trying to imply it, but YC funding defense tech under the guise of funding toys for the ultra-wealthy would be interesting, but I don't honestly think that's what's going on here. I don't think they're likely to develop novel turbine technology, and the concept of a one-person turbine flying device left the US military unimpressed decades ago. There doesn't really seem to be a tactical niche for it on the battlefield.
Anyway... the military isn't always the ideal market force for driving down costs.
also the most pertinent problem with a thousand similarly idiotic ideas, from edible knives to jetpacks
All engines have lifespans measured in hours. Jetcat engines have service intervals of 25-50 hours, which usually involves bearing replacements, inspection, cleaning etc.
Non-RC small engines have very normal service intervals of 1000s of hours, right on par with large jet engines and as long or longer than piston engines. The JFS100[1] is slightly more powerful than a JetCat 550, and is a bona fide helicopter engine. Helicopters[2] have used small <100 hp turbojet engines for decades. They're cheap and incredibly reliable. Those JFS 100s go for <$4,000.
They don't have the same power/weight ratio as jetcats because they're used to drive props- there is no demand for tiny jet engines because props are more efficient and jets require too much reduction for slow speed personal aircraft.
> The video is a bit suspicious. It's very quiet. You can hear the boats over it. It doesn't blow stuff around. It doesn't move his clothing. It doesn't ripple the water even at low altitude. Other videos of small jet engines are very noisy and have lots of jet blast.
This is excessively incredulous. The flyboard is well documented and perfectly reasonable. These people balance on jets of water without computers and jet engines are built to be trimmed in to match each other closely. Otherwise you'd have planes going in to flat spins when they pushed the throttle too hard.
He never goes near the water in that video, it's loud as hell, the only boat you can hear is a cigarette boat (which is basically a drag car), and he's wearing full leathers. Of course they aren't rippling. How would they fake a video like this[3]?
[1]: http://nyethermodynamics.com/jfs100/index.html
I think it's slightly more correct to say that they have a service interval measured in hours. The jetcat ones require service every 25h of use, but there are other companies that require service less frequently, although the highest interval I found is 100h.
Another important reason is fuel consumption. Jet engines in general are extremely thirsty, AFAIK the only reason they became (unexpectedly!) competitive with piston engines is that they allow the planes to fly so much higher where the air is thinner.
In addition, small turbines are even less efficient than big ones.
Small has been done and cheaper is always possible, but significantly reducing the noise of jetpacks would require an amendment to the laws of fluid dynamics.
As for visible effects of the jet: at liftoff, the tether, that was detached by one of the crew just before, blows around a bit. I am trying to decide if you can see the jet as a distortion of the background, or whether that is an artifact of video decompression. The best opportunity for seeing it appears to be just after liftoff, when the right engine nozzle is seen with the cruise ship behind it, but there doesn't seem to be much of an effect there. As he approaches for landing, the netting around the pad appears to be blown around.
I thought they were over water due to FAA regulations. From an article about Larry Page's Kitty Hawk Flyer. [1]
> > In the US, the Flyer falls under the FAA's rules for ultralight aircraft, meaning no pilot's license is needed so long as it's flown over water or "uncongested areas."
[1] https://www.cnet.com/roadshow/news/kitty-hawk-flyer-electric...
https://en.wikipedia.org/wiki/Moller_M400_Skycar
FWIIW Moller's project is a great example of why this is hard.
It doesn't even seem to move the clothing of the guy that ducks behind him around 2:30.
There are a few paint flakes that come off and blow around a bit at 2:50 or so.
Five engines in the render, assume 1 is redundant:
705lbs to metric: 3134N. Divide by 4 = 784N which is _exactly_ the max thrust of a Nike.
With a 231lb empty weight, 180lb rider, and 5 gallons of kerosene (ultra light version) you get
104kg + 81kg + 15 kg = 200kg
sfc of a Nike is 40 grams / (kN second) (Should have gone with Hawk ;) )
Lets say hover thrust on a nice still day will be around ~ 1.9kN -> 76.7grams per second of flight.
Assuming I've not made any mistakes that gives roughly 3.5 minutes of hovering flight on that 15kg of fuel (ignoring the fact the vehicle gets slightly lighter as the fuel burns off).
That sort of matches up with the spec, assuming the 10-22 minutes stated is for a lighter human on the experimentally licensed version of the vehicle.
You can get model aircraft jet engines with enough power for this.[1] Various human-carrying craft have been built that way, such as the Zapata Flyboard.[2] But the engines have a lifespan measured in hours and not enough reliability for carrying humans. That's why all the demo videos of these things are over water, or tethered.
People have been trying to build small, cheap jet engines for decades. "Small" has been done. Cheap, no. Below bizjet size, the price doesn't go down much. Which is why general aviation is still running mostly on pistons. The 1960s Williams jetpack (not the Bell rocket belt) used an engine intended for cruise missiles.
If they've cracked the small jet engine problem, there's a big market for those, without trying to package them as jetpacks or motorcycles. Otherwise, it's just another demo rig.
The video is a bit suspicious. It's very quiet. You can hear the boats over it. It doesn't blow stuff around. It doesn't move his clothing. It doesn't ripple the water even at low altitude. Other videos of small jet engines are very noisy and have lots of jet blast.
[1] http://www.jetcat.de/jetcat/Kataloge/JetCat%20ENGINES.pdf
[2] https://www.youtube.com/watch?v=7feIt5PRvUw