Electrified wingsuit from BMW reaches 186MPH on first flight • Hacker News Board

Re: Electrified wingsuit from BMW reaches 186MPH on first flight

#141

Post by sudosysgen » Sun, Nov 15, 2020, 10:08 PM UTC

Robotbeat wrote: post #12

Lithium-based batteries (and associated tech) are to the 21st century what the internal combustion engine was to the 20th century and what the steam engine was to the 19th century. There’s a ~90% chance you’re using a device powered by a lithium chemistry battery to read this right now (laptop or tablet or phone). The smartphone alone (enabled by lithium based batteries) has transformed the world. Lithium-based batte…

Isn't the efficiency of jet turbines, even microjets, wildly dependent on velocity? I don't know how you can calculate an efficiency without qualification.

Re: Electrified wingsuit from BMW reaches 186MPH on first flight

#142

Post by ksrm » Sun, Nov 15, 2020, 10:24 PM UTC

CrazyCatDog wrote: post #19

Hnrobert42 wrote: post #17

Earlier quoted context omitted.

If you are so inclined to answer, I’d live to know why lithium batteries and not some other form of battery? That is, do other elements not have the right properties? Are they too rare? Are they dangerous? You sort of answer a bit in your last paragraph. Why did it take until now to get to lithium batteries? Why way NiCad the thing before? Will lithium continue to dominate, or are there other competitive solutions ju…

NiCd is actually more capable than NiMh, but suffers from memory issues (capacity decreases significantly if not carefully discharged and recharged; ie you cannot “top them off” without sacrificing capacity. Again, speaking from my lived experience, NiCd pushed to the limit resulted in many gnarly fires in high performance RC use, NiMh was never a contender given low output (again low discharge rates). LiPo is king h…

LiPo is a type of Li-ion battery and they have much the same safety characteristics. Lithium iron phosphate (LiFePO4) batteries are much safer, they don't tend to run away.

Re: Electrified wingsuit from BMW reaches 186MPH on first flight

#143

Post by Toutouxc » Sun, Nov 15, 2020, 10:28 PM UTC

heavenlyblue wrote: post #69

reaperducer wrote: post #68

I saw this on the news a couple of days ago. It stated that flight time is about five minutes before the battery runs out. That time in "flight" doesn't seem much different than the time it would take to plummet to your death. The only material difference seems to be the not dying part.

You could use these suits to help pilots who can’t land their plane - they literally only need a few moments of “burn” close to the surface

We already have those, they're called "parachutes". They're easier to operate, safer and don't require power.

Re: Electrified wingsuit from BMW reaches 186MPH on first flight

#144

Post by nonesuchluck » Sun, Nov 15, 2020, 10:33 PM UTC

tachyonbeam wrote: post #78

simias wrote: post #61

Earlier quoted context omitted.

Quadcopters also usually have terribly autonomy. Gliding is a lot more efficient at conserving energy so there's still a lot good engineering to be had in aerodynamics whenever you need to be in the air for more than a handful of minutes at a time. That's why if you look at professional drones you generally only see quadcopters when being able to hover and/or execute very precise motions is required, for the rest win…

It seems to me like there's a good future for electric VTOL. Whether for package delivery or for carrying people, you can take off vertically, and then transition to a horizontal flight regime using wings that's more energy efficient, so you can get more range.

This feels like the golden path to me, too. Lilium is claiming 300km range at 300km/hour, and appears to transition nicely to horizontal flight. Maybe not a great glide ratio on those stubby little wings, but it looks safer than quadcopters. They don't need all 36 ducted fans for normal flight, so eating a bird shouldn't spell death.

Has anybody else shown off similar craft? Uber Air's eVTOL looks about 50% CGI/50% hype, but maybe I've missed something.

Re: Electrified wingsuit from BMW reaches 186MPH on first flight

#145

Post by Toutouxc » Sun, Nov 15, 2020, 10:36 PM UTC

Why does this, of all things, have to be electric? It's a wing suit. They're basically strap-on death. Their glide ratio is somewhere between a really bad plane and a brick, they're unusable in any shape or form for real transportation. They could've had gone with a jet or even a rocket engine and it wouldn't have made the thing more dangerous or less green or anything.

Don't get me wrong, I love it, but I don't really see what they were seeing when they made this.

Re: Electrified wingsuit from BMW reaches 186MPH on first flight

#146

Post by duxup » Sun, Nov 15, 2020, 10:45 PM UTC

Are these way safer than say the base jumping type wing suits?

Obviously they're powered so they're different, but I remember a lot of wing suit debates where even professionals felt that the envelope between 'safe' and disaster on wing suits was way too small for even professionals to use. A lot of that seem to have to do with the jumper's sense of how stable they are / compared to how stable they actually are and how that could get way off at times and even pro's weren't able to manage them well enough.

Re: Electrified wingsuit from BMW reaches 186MPH on first flight

#147

Post by im3w1l » Sun, Nov 15, 2020, 11:01 PM UTC

robotresearcher wrote: post #116

Diggsey wrote: post #75

Earlier quoted context omitted.

With a helicopter, even if you lose the motor (lift) you still have control by adjusting the pitch, angle and ratio of the blades. A quadcopter depends on the motors for any control. While it is possible to regain control after a single motor failure on a quadcopter, it's extremely difficult and not something a human pilot could do, so you'd be relying on software. Also, if you don't detect the failure instantly, the…

Multirotor designs are not limited to 4 motors. You can add more for redundancy. Four is common because it’s the smallest number that has good control characteristics.

Mind explaining that one? To me it seems they have an unnecessary degree of freedom: the "diagonal" one.

    ox
    xo

What issues do you get with three motors in an equilateral triangle?

EDIT: I managed to find it, with even number of motors you can prevent unwanted yawing, by letting half spin clockwise and other half spin counterclockwise.

Re: Electrified wingsuit from BMW reaches 186MPH on first flight

#148

Post by Robotbeat » Sun, Nov 15, 2020, 11:03 PM UTC

jononor wrote: post #132

CrazyCatDog wrote: post #49

Earlier quoted context omitted.

Totally agree. My use case: 3 seconds max (launch), 3 seconds in-flight would be out of sight— total power on time between charges is well below one minute. I’m tempted to guess that this would be the most efficient way of converting electricity in wing suit applications as well.

That is more supercapacitor territory than batteries, especially if you do not require long-term energy storage (can accept relatively high self-discharge). The energy recovery systems in Formula 1 racing (KERS) are examples.

What’s interesting is that in many cases, LiPos can equal the specific power of supercapacitors!

Re: Electrified wingsuit from BMW reaches 186MPH on first flight

#149

Post by hamburglar » Sun, Nov 15, 2020, 11:09 PM UTC

bredren wrote: post #102

thimkerbell wrote: post #72

Earlier quoted context omitted.

Where?

I’m not going to post the link but they are called Twharf D Cell Batteries 1.5V/5000mAh D Batteries Micro. I really could not believe it when I charged them for the first time. Here is a pic https://i.imgur.com/2LoyZlR.jpg

Those look incredibly useful. I'll be ordering some in the future if they are still around and don't seem to have any reliability/safety issues (I'm slightly wary of Lithium batteries being crammed into places that haven't been thoroughly tested for that application, given the tendency of these things to catch fire. A Mag-lite with lithium batteries would be great but resembles a pipe-bomb a little too much for comfort until they're proven.)

Re: Electrified wingsuit from BMW reaches 186MPH on first flight

#150

Post by lillecarl » Sun, Nov 15, 2020, 11:15 PM UTC

palijer wrote: post #67

joosters wrote: post #60

Earlier quoted context omitted.

I don't understand the lasting appeal of quadcopters in particular. We can build remote-controlled 'normal' helicopters that have fantastic performance and much greater efficiency (no need for 4x the motors and stubby blades). The only downside I understand is that R/C helicopters are very difficult to fly, but that should be straightforward to overcome by putting a basic computer + sensors between the controller and…

Having 4 weaker motors is generally safer than one big one if something were to hit it, and you can shorten the blades because the lift is spread across 4x as many blades. Multiple motors is good as well for any motor failures, as quads (if they're well designed) can fly after even multiple motor failures.

If you lose power on a quad they become unstable, if you lose power on a heli you can pitch the blades slightly downwards which keeps rotation in them and level out close to the ground landing perfectly smooth. IIRC this is something you practice to get your license. Can be done with both RC helicopters and real ones.