aonsquared

9 minutes ago, brenthutch said:

Oxygen, cuts steel much better that your puny CO2 laserhttps://en.wikipedia.org/wiki/Oxy-fuel_welding_and_cutting , and water vapor traps vastly more energy than CO2 could ever hope to. As far as my facial, just show me you beauty school diploma and next time you are in State College you can laser away.

I use it as a high-precision cutter for many materials, not just steel. But CO2 is good enough that it was a contender for the Boeing YAL-1 Tactical Laser for shooting down ballistic missiles. So yes, I'll take you up on that offer.

Yes, water vapour does absorb more energy than CO2, but that's not the point - if we had 2 identical earths, one with normal prehistoric CO2 concentration and one with 400ppm as we do now, then expose them to the same amount of sunlight, the one with more CO2 will heat up more.

We can do this as an experiment with 2 identical vacuum containers with say 10000 ppm water vapour. now let's add 400 ppm CO2 to one and 100ppm to the other, then expose both to sunlight. Sure, both containers will heat up mostly due to water vapor, but the one with more CO2 will heat up more. It's a high-school level experiment.

 

To simplify even further, imagine microwaving a cold meal - sometimes you take it out and the middle is still freezing cold. But one bit of it is blazing hot, and if you take the average temperature, it's hotter than before you put it in the microwave. And if you mix it then it will be warmer. It's basic thermodynamics. Now the earth is one huge container and it will take time to fully mix the heat. But by then it could be too late - we need to remove the bit that's absorbing the extra energy (CO2) as soon as we can.

Just now, brenthutch said:

No problem, I'm game.  But why are you so hell bent on giving me a facial?

https://www.webmd.com/beauty/laser-resurfacing#1

Well you did get the laser part right - I'm talking about a 120 Watt CO2 laser that I use regularly for work.

It will take off wrinkles and pretty much the rest of your face. With long enough exposure, it will punch a hole through you (it's only 120 watts, so will take a minute or so). It will actually make your eyeballs explode too.

You see, CO2 has this property that it absorbs energy into its molecular bonds, then re-transmits it in the 10-micron wavelength. This property is useful for cutting through steel, but it's also the exact thing that's causing climate change. Now since the mathematics is too hard even for supercomputers to simulate properly, the exact effect of the energy is hard to predict, but we are effectively pumping Gigawatts, if not Terawatts of extra energy into the atmosphere via CO2.

So, shall we arrange a time and date for your "facial"?

22 hours ago, brenthutch said:

Cherry picked start date.  If they went back twenty years instead of thirty, it would show cooling.

You avoided answering my question on standing in front of a glass tube filled with CO2 in the other thread. It's almost as if you don't know what was going to happen with such a "harmless" gas. Are you chickening out?

For further clarification, the gas is not pressurised, it will not leave the glass tube and will not be inhaled or otherwise come into contact with you. You just need to stand in front of it while it is switched on.

Just now, brenthutch said:

CO2? Harmless.  Mirrors? Absolutely terrifying

I'm serious. Are you in?

3 hours ago, brenthutch said:

What does avoiding risky sexual practices have anything to do with a phobia?  Let's get back on topic and discuss your irrational and extreme fear of CO2. 

If I put some CO2 in a discharge tube, add some optics and mirrors, will you stand in front of it while I turn it on? After all CO2 is nothing to be afraid of.

29 minutes ago, mbohu said:

In a computer there is really nothing else but a large number of gates (which are physical objects that hold a physical state). These gates are connected in a way that certain results can be produced when the gates change their states. "Information" is simply an abstract concept that in essence describes the physical states of these gates.

How is this qualitatively different from a large number of neurons, connected in a certain way, producing results when certain neurons change their states?

"Consciousness" is simply an abstract concept that in essence describes the physical states of these neurons.

Just now, mbohu said:

Where does "our mind" exist? 
(Thanks for indulging me here, I am trying to get you to understand what I am trying to say, so if you could simply answer this question like you did the last one. I am not trying to be annoying with these questions)

A computer hard drive with a computer program weighs exactly the same as one that is empty. Where does the program exist?

It exists in information. Our mind exists in the firing patterns of our neurons. I highly suggest looking up Information Theory to answer some of your questions.

8 hours ago, coticj said:

It is still useless for skydiving and it is going to remain such for a long time. As previously mentioned, you would need a 100kWh battery pack to get a load with a 206 up. The most advanced battery pack on the market currently (the one found in Tesla M3) weighs 168 Wh/kg. So a 100kWh battery pack weighs about 600kg. The one that would be made specifically for a plane wouldn't have such density, but lets ignore that.

A C206 has a max payload of around 650kg.

You will get some weight saving with the engine which is only 72kg as opposed to the 220kg of the IO520.

So with the engine weight saving you would get around 200kg of usable payload. So a pilot and 2 very light skydivers.

The Caravan would get you slightly better results, but still unusable for a real operation. The are mentioning 105 miles of range - yeah, but at a very low power setting, in cruise.

 

I would very much like to know where you get fuel that weighs 0kg...now that would be a bigger game-changer than electric

In any case, here are the official weights from the Cessna website for the Turbo Stationair HD Cargo:

Maximum Ramp Weight     3,806 lb (1,726 kg)
Maximum Takeoff Weight     3,789 lb (1,719 kg)
Maximum Landing Weight     3,600 lb (1,633 kg)
Usable Fuel Weight     522 lb (237 kg)
Usable Fuel Volume     87 gal (329 l)
Basic Empty Weight     2,212 lb (1,003 kg)
Useful Load     1,594 lb (723 kg)
Maximum Payload     1,388 lb (630 kg)
Full Fuel Payload     1,072 lb (486 kg)

You won't really lose that much payload with electric, and they're just getting started

First is I would recommend wearing foam ear plugs to protect your hearing - I've just started doing this and to my amazement I could actually hear conversations in the plane over the earplugs, yet the noise level was reduced to a comfortable level.

I also had no problem hearing my audible. I'm sure any would do fine, although I am a bit biased, as I do work for the company who makes the Brilliant Pebbles (which the volume could be set to 255 different levels so you should be able to get exactly the alarm volume you need)

Most other audibles I've seen can control the volume as well (the NeoXS had 4 different volume settings if I remember correctly).

47 minutes ago, frontloop33 said:

I think there is way to go until electric aircraft will be usable.

On flyer.co.uk they say, that the range of the electric caravan is about 105 miles.

If I compare that to our Pilatus Porter, we need about 27 - 30 miles to get us on height. So lets say 40 miles per load (the plane has to get back on the ground).

Therefore every 2 - 3 loads a recharge is needed. I doubt that this is done in a couple of minutes like on conventional planes...

Electric aircraft can also have something like regenerative braking for cars, and recover some energy on the descent, reducing the recharge needed between lifts and reducing total fuel cost even further. Regular engines can't do that.

The charging time is still a problem for quick turnarounds common in skydiving, but battery tech is improving quickly.

Actually, a Flysight would probably be even better, as it uses GPS and is not dependent on barometric pressure.

AON2 X2

For how much the AresII is, you might as well get GPS and a colour screen

(disclaimer: yes I do work for AON2!)

Sorry But my suggestion is to look at flow separation - it happens really early on wingsuits, creating lots of extra drag and wasting that extra surface area. Somehow find a way to keep that boundary layer attached, and you can cut drag way down. Keep lift the same, and your L/D will shoot up :)

yuri_base

Which insult to standard aerodynamics did I make? About splitting the total drag into parasite and induced? That's not an insult, I simply argue that this split is completely unnecessary for WS and makes weak minds get lost in a forest of two trees.

We'll have to agree to disagree on the 'unnecessary' bit - if it's not useful to you, so be it. I shall now get back to my own work and stop arguing Carry on!

So given accelerations in X and Y, resolve the forces to tangent (D) and perpendicular (L) to the velocity vector in a uniform gravitational field, g.

Yes, you get:
L/D = (gVx-AyVx+AxVy)/(gV_y-VyAy-VxAx)

It's high school level mathematics.

How does this invalidate standard aerodynamic equations? How is this revolutionary? What other things do they say?

That was Yuri's claim. That's why I kept asking if his equations gave anything more than L/D, which he never answered. When I said they were wrong, it was because my definition of "flight" did not include completely ballistic trajectories, which this L/D includes (I still think it's silly, but it's just a matter of convention). So at least for this L/D equation, I take my statement back. (Yuri will of course start dancing and try to include me in his "religion", no thanks )

So in short, the "WSE" is a way to calculate accelerations given velocities, then resolving them in the "lift-drag" coordinate system. Not wrong, but not new, nor novel or groundbreaking.

But since Yuri's stopped insulting standard aerodynamics, I see no reason to keep arguing

yuri_base

Their S/N ratio is the highest?

You wish. Excellent strategy though, just keep spamming the thread, and avoid engaging experts who can actually see through your claims. People will believe you eventually

yuri_base

I carpet-bomb with formulas until naysayers drop dead from exhaustion.

You know what they say about those who shout the loudest...

You're not going to get any straight answers from him, he'll just post more photos of his vane and some unrelated rants.

Yuri's conclusion for the max L/D ratio is not because of his equations, he's actually concluded that the human planform will have a lower limit to drag which will limit L/D. Which is quite reasonable overall, except that he set that lower limit to one of his graphs and declared that it's impossible to go lower

He uses neither Bernoulli's equation nor Euler's formula - it's way more basic than that.

Yuri, besides L/D ratio, do your equations say anything else useful?

What else does the "WSE" give besides L/D? How do the "WSE" invalidate standard aerodynamic equations?

There's a lot of noise in this thread, and it's definitely *not* coming from LeeroyJenkins.

yuri_base

Anyone succeeded in debunking WSE?

We need to clarify terms. With proving them wrong, do you mean mathematical proof, or physical proof?

Ever heard of proof by contradiction?

According to your earlier posts, do your wingsuit equations assume that either:

a) L points perpendicular to the trajectory curve? Or
b) L always points "up" opposite the gravity vector? Or
c) perpendicular to the wingsuiter?

Just trying to establish your conventions.

platypii

Fair enough, you're right that with changes in airspeed and angle of attack, the L/D will also change. I glossed over this a little, but also tried to acknowledge it when I pointed out the variation in L/D in a typical glider polar curve.

The L/D will change throughout a flight, but not by very much actually. It will change by moving along the wingsuit's characteristic polar curve. The l/d won't swing between wildly between 2:1 and 5:1 like the glide ratio does.

Here is a chart of the "sustained speed polar" which uses the wingsuit equations to compute "sustained" horizontal and vertical speeds. In theory this is roughly what would be measured by aerodynamic instruments like airspeed and glide angle on an aircraft. The purple line shows the sustained speeds from the same jump as above, and you can see they fall within a fairly narrow range. The green line is my attempt at ballpark estimating a wingsuit's polar curve. That's why I would expect the L/D to not vary by much throughout the flight.

platypii

Chart attached with all speeds: total, groundspeed, fallrate. Plus glide and l/d.

Accuracy on this track seems okay. Jump is sensitive, so can't share the data, but will see if I can find a similar one that I can.

Platypii,

I think you need to step back here and look at your logical reasoning. You made a hypothesis (L/D ratio is roughly constant on this flight), then measured ground Vx and Vy through GPS.

Then critically, without measuring lift nor drag nor its ratio with any other method, you say that since the L/D calculated from yuri's equations looks like your hypothesis, then it must be correct.

You looked at glide ratio varying wildly and stayed on this train of thought: "it doesn't match my hypothesis, so it must be wrong". (and yes, instantaneous GR is definitely not a sensible aerodynamic measure, but instantaneous GR being wrong doesn't automatically mean yuri's equations are correct)

But why not use any number that stays roughly constant?

I can multiply air density by 2.44 and tell you it's L/D ratio for your flight, and it would match your hypothesis better than the GR data, but there would be no logic behind it.

To properly prove something, it needs to be able to make predictions that are independently verifiable, and not just because it "looks" right.

Thanks for the plot. Now it's a bit clearer.

First off - instantaneous glide ratio is not a measure of L/D ratio and should not be. In the flat part of a flare (vertical speed = 0 for a fraction of a second) then instantaneous glide ratio would be infinity.

However average glide ratio over the entire flight can give an indication of total L/D ratio. So if you integrate the area under the glide ratio curve then average over the interval, you should get to a similar value. You still need PDOP values though, as no instrument is perfectly accurate even with filtering. And you need to post filtering details too...science is difficult, but it does pay off when done properly and without taking shortcuts
Again, I'm not really seeing anything new or revolutionary?

platypii

The l/d won't swing between wildly between 2:1 and 5:1 like the glide ratio does.

It's a bit unfair to say that glide ratio varies massively without posting details of what instrument you used to measure glide ratio. If it's GPS, please post how the PDOP varied throughout the flight.

Same for the red line please - what instrument was used to measure it? The linear steady decrease indicates a roughly constant vertical (and thus horizontal) speed.

platypii

It wasn't constant airspeed nor constant glide. The flight went through a few phases and angles of attack, but as much as possible, the same body configuration.

The green line is groundspeed / fallrate, the purple line is L/D calculated based on wingsuit equations.

Also, that doesn't match what you show on the graph. Red line shows a steady, linear decrease in altitude vs. time, which implies constant vertical speed.

Is the green line from the GPS? Could you also include PDOP (position dilution of precision) in the graph so we can see how accurate it was? With high (bad) PDOP values a GPS can show hundreds of m/s speed while the receiver is not moving.