9 ms·

Lacks the safety features of airplanes (gliding) or helicopters (autorotation), has terrible rotor placement and small air time. I would advertise it as "your p

by Jnr 5y ago

Lacks the safety features of airplanes (gliding) or helicopters (autorotation), has terrible rotor placement and small air time. I would advertise it as "your personal death machine". :) No amount of money would make me use that thing. EDIT: Ok, sorry, it says it has a parachute, but I still would not use it.

ChrisMarshallNY 5y ago
Parachutes have a minimum altitude. For standard human chutes, that’s 300 feet (100 meters) or so. Not sure what the ceiling is on this. They don’t have footage of it going too high. You only need to fall 30 feet (10 m), to buy the farm. Less, in many cases (depending on how you fall, and onto what).
- KineticLensman 5y ago
  Yes. This is why paragliding from hills is more dangerous than regular parachuting from a plane. Your paraglider canopy can collapse due to bad wind or unexpected updrafts at say 40 feet from the ground and you slam into the ground before it recovers. In contrast, when a parachute malfunctions on a freefall deployment, you are often higher than 2000ft, and there is plenty of time to deploy a reserve, fix twisted lines, etc.
  - cannabis_sam 5y ago
    Beyond the risk level of ground take-off paragliding (and related activities), you have (in my subjective order of least to most risk) wingsuit fliers, base jumpers and then you of course have base jumping wingsuit fliers.. Yet, people still do it..
  - nikitaga 5y ago
    What are you comparing, deaths per flight, per flight hour, per participant per year? Do you distinguish tourists, hobbyists, and competitors? What about injuries? Credible and reliable data for such comparisons does not exist, unfortunately. Paragliders who aren't idiots don't spend much time at 40ft AGL in weather conditions that can cause a collapse. And not every low altitude collapse is fatal. Spine compression injury is more likely, and they wear padding on their butt to minimize that (some even have airbags). For better or worse, the main predictive risk factor in paragliding is personal attitude, and I suspect it's the same in parachuting.
    - KineticLensman 5y ago
      Anecdata I know, but I parachuted for two years and paraglided for a year (before airbags were a thing). I saw more injuries in paragliding and people I know broke hips, twisted ankles and bashed into dry-stone walls (head saved by a helmet, which was itself destroyed). The broken hip was a club instructor who was caught out landing. In my parachuting experience I saw only one really bad accident: in an accuracy contest, a guy who was going to miss the target by a few feet, reached out with his feet and landed on the base of his spine. Stretchered away. My own skydiving parachute malfunction occurred on opening at approx 2500 ft. The bastard main failed to emerge and I deployed my front-mounted reserve. The act of flipping onto my back unjammed the main and for a moment I had two canopies opening. The main won and I spent half a minute pulling in the reserve canopy so I could see where the fuck where I was going. I didn't get the shakes until about ten minutes after landing. The jumpmaster confirmed the sequence of events and I got back on the horse and jumped again 40 minutes later. YMMV
- VLM 5y ago
  > Parachutes have a minimum altitude. If you have the money, zero/zero ballistic parachutes have been a reliable thing for more than half a century. For ultralight sized aircraft, they cost about 1/5 the cost of a new airframe. Generally they don't provide much survivability IMHO. Most ultralight deaths seem to boil down to CFIT and similar "happened too fast too close to ground" incidents with a side dish of refusal to do maintenance, and you know they're not going to maintain their airframe parachute or how its attached or how to engage it if they refuse to maintain their engine... But they are available and in special cases they might be useful.
  - NovemberWhiskey 5y ago
    >If you have the money, zero/zero ballistic parachutes have been a reliable thing for more than half a century. That's called an ejection seat, right? As in a rocket-propelled vehicle to launch you sufficiently high out of your aircraft to allow your parachute safely to deploy (i.e. about a hundred meters, as described in the prior post)
    - IshKebab 5y ago
      No, it's a parachute that is deployed via a small explosion so it doesn't rely on falling through air to open.
      - NovemberWhiskey 5y ago
        Can you provide a link to such a system? I did a best-efforts search and failed to turn up anything.
        brianwawok 5y ago
        https://en.wikipedia.org/wiki/Ballistic_parachute https://en.wikipedia.org/wiki/Ballistic_parachute
        NovemberWhiskey 5y ago
hwillis 5y ago
Electric motors can autorotate just fine: https://youtu.be/QADYnVeHQOQ https://youtu.be/QADYnVeHQOQ You can't descend quite as slow as a normal engine because the motor has somewhat more friction at low RPM, even though it's similar to free-spinning at higher RPM. That makes for a rougher final approach but just as much glide distance and control. Small rotors will make it more of a hassle but should still be quite safe. Even if you do end up touching down hard, there's way less angular momentum stored up and you wouldn't have the chaos of giant blades exploding. Of course there's still the batteries, since li-ion cells have only slightly less energy than kerosene when burned. A parachute is... not the kind of safety feature that should be relied on. Parachutes take >100 feet to open properly. 20 foot falls can easily be lethal.
- ramesh31 5y ago
  >Even if you do end up touching down hard, there's way less angular momentum stored up and you wouldn't have the chaos of giant blades exploding. That angular momentum is what allows autorotation to be possible. Theres zero chance a quadcopter blade could maintain enough energy to autorotate while carrying the weight of a person. The blades are also fixed pitch, which would make a landing flare impossible.
- Toutouxc 5y ago
  > Electric motors can autorotate just fine Your video shows an electric helicopter with a full size helicopter main rotor, which is not what the Jetson vehicle uses.
- nradov 5y ago
  That is dangerously incorrect. Successful autorotation requires high inertia rotor systems with controllable blade pitch. Small rotors like on this Jetson don't have anywhere near enough inertia, and it looks like they're running fixed pitch props. The type of motor is irrelevant as long as the motors can be de-clutched from the rotors.
- Justin_K 5y ago
  You should look up auto rotate and variable pitch propellers

by Jnr 5y ago

ChrisMarshallNY 5y ago

Parachutes have a minimum altitude. For standard human chutes, that’s 300 feet (100 meters) or so. Not sure what the ceiling is on this. They don’t have footage of it going too high. You only need to fall 30 feet (10 m), to buy the farm. Less, in many cases (depending on how you fall, and onto what).

KineticLensman 5y ago
Yes. This is why paragliding from hills is more dangerous than regular parachuting from a plane. Your paraglider canopy can collapse due to bad wind or unexpected updrafts at say 40 feet from the ground and you slam into the ground before it recovers. In contrast, when a parachute malfunctions on a freefall deployment, you are often higher than 2000ft, and there is plenty of time to deploy a reserve, fix twisted lines, etc.
- cannabis_sam 5y ago
  Beyond the risk level of ground take-off paragliding (and related activities), you have (in my subjective order of least to most risk) wingsuit fliers, base jumpers and then you of course have base jumping wingsuit fliers.. Yet, people still do it..
- nikitaga 5y ago
  What are you comparing, deaths per flight, per flight hour, per participant per year? Do you distinguish tourists, hobbyists, and competitors? What about injuries? Credible and reliable data for such comparisons does not exist, unfortunately. Paragliders who aren't idiots don't spend much time at 40ft AGL in weather conditions that can cause a collapse. And not every low altitude collapse is fatal. Spine compression injury is more likely, and they wear padding on their butt to minimize that (some even have airbags). For better or worse, the main predictive risk factor in paragliding is personal attitude, and I suspect it's the same in parachuting.
  - KineticLensman 5y ago
    Anecdata I know, but I parachuted for two years and paraglided for a year (before airbags were a thing). I saw more injuries in paragliding and people I know broke hips, twisted ankles and bashed into dry-stone walls (head saved by a helmet, which was itself destroyed). The broken hip was a club instructor who was caught out landing. In my parachuting experience I saw only one really bad accident: in an accuracy contest, a guy who was going to miss the target by a few feet, reached out with his feet and landed on the base of his spine. Stretchered away. My own skydiving parachute malfunction occurred on opening at approx 2500 ft. The bastard main failed to emerge and I deployed my front-mounted reserve. The act of flipping onto my back unjammed the main and for a moment I had two canopies opening. The main won and I spent half a minute pulling in the reserve canopy so I could see where the fuck where I was going. I didn't get the shakes until about ten minutes after landing. The jumpmaster confirmed the sequence of events and I got back on the horse and jumped again 40 minutes later. YMMV
VLM 5y ago
> Parachutes have a minimum altitude. If you have the money, zero/zero ballistic parachutes have been a reliable thing for more than half a century. For ultralight sized aircraft, they cost about 1/5 the cost of a new airframe. Generally they don't provide much survivability IMHO. Most ultralight deaths seem to boil down to CFIT and similar "happened too fast too close to ground" incidents with a side dish of refusal to do maintenance, and you know they're not going to maintain their airframe parachute or how its attached or how to engage it if they refuse to maintain their engine... But they are available and in special cases they might be useful.
- NovemberWhiskey 5y ago
  >If you have the money, zero/zero ballistic parachutes have been a reliable thing for more than half a century. That's called an ejection seat, right? As in a rocket-propelled vehicle to launch you sufficiently high out of your aircraft to allow your parachute safely to deploy (i.e. about a hundred meters, as described in the prior post)
  - IshKebab 5y ago
    No, it's a parachute that is deployed via a small explosion so it doesn't rely on falling through air to open.
    - NovemberWhiskey 5y ago
      Can you provide a link to such a system? I did a best-efforts search and failed to turn up anything.
      - brianwawok 5y ago
        https://en.wikipedia.org/wiki/Ballistic_parachute https://en.wikipedia.org/wiki/Ballistic_parachute
        NovemberWhiskey 5y ago

hwillis 5y ago

Electric motors can autorotate just fine: https://youtu.be/QADYnVeHQOQ https://youtu.be/QADYnVeHQOQ You can't descend quite as slow as a normal engine because the motor has somewhat more friction at low RPM, even though it's similar to free-spinning at higher RPM. That makes for a rougher final approach but just as much glide distance and control. Small rotors will make it more of a hassle but should still be quite safe. Even if you do end up touching down hard, there's way less angular momentum stored up and you wouldn't have the chaos of giant blades exploding. Of course there's still the batteries, since li-ion cells have only slightly less energy than kerosene when burned. A parachute is... not the kind of safety feature that should be relied on. Parachutes take >100 feet to open properly. 20 foot falls can easily be lethal.

ramesh31 5y ago
>Even if you do end up touching down hard, there's way less angular momentum stored up and you wouldn't have the chaos of giant blades exploding. That angular momentum is what allows autorotation to be possible. Theres zero chance a quadcopter blade could maintain enough energy to autorotate while carrying the weight of a person. The blades are also fixed pitch, which would make a landing flare impossible.
Toutouxc 5y ago
> Electric motors can autorotate just fine Your video shows an electric helicopter with a full size helicopter main rotor, which is not what the Jetson vehicle uses.
nradov 5y ago
That is dangerously incorrect. Successful autorotation requires high inertia rotor systems with controllable blade pitch. Small rotors like on this Jetson don't have anywhere near enough inertia, and it looks like they're running fixed pitch props. The type of motor is irrelevant as long as the motors can be de-clutched from the rotors.
Justin_K 5y ago
You should look up auto rotate and variable pitch propellers