nwt

2 minutes ago, Phil1111 said:

Mortality divided into total cases. US v Canada

There's your problem--that isn't how you calculate case fatality rate or anything useful. Total cases includes a bunch of people who will die but haven't done so yet, which throws off the result.

3 minutes ago, Phil1111 said:

Canada is 11 percent of US pop. This is where i get my info: https://covid19tracker.ca/

So something doesn't jive.

What doesn't jive?

Going off the numbers from your source, CFR = deaths / (deaths + recoveries) = 10,853 / (10,853 + 228,189) = 4.5%

That's worse than the 3.8% depicted on the chart I posted.

21 hours ago, Westerly said:

I'm advocating we release the vaccine now to anyone who wants it. Yes it will take time to make and I get that, but for everyday we screw around with more testing is another day that thousands will die. In the end the vaccine will get approved eventually anyway and all this waiting will have accomplished is hundreds of thousands that will be dead that otherwise wouldent have been if they were able to get the vaccine out sooner. It will be a case of 'oh, I guess the vaccine WAS safe and effective after all, good thing we made everyone wait for no reason". There is a good reason to test drugs, but sometimes there is a good reason cut corners as well. This is a case where quantity matters more than quality.

Why now? Why not months ago? Why not approve every vaccine candidate that anyone dreams up, before it's even synthesized for the first time?

I'm sure you'd agree that it's possible to approve something *too* early. The FDA is moving this along more quickly than they ever have moved anything along the past. They have all the information and they intend to approve it as soon as the time is right and not a moment later. They operate on all pertinent details, not just "so many people are dyeing every day so we'd better just approve it now". The FDA hasn't approved it yet, and so we can be sure that they think approving it now would be *too* early. Why do you think your information or judgement is superior than that of the FDA?

6 hours ago, Phil1111 said:

Canada currently has 24% of the covid cases that the US has per population.

Canada currently has 40% of the covid fatality rate that the US has per population.

Canada has 11% of US pop.

Perhaps single payer health care has better health outcomes. Perhaps a socalist-commie Prime Minister is better than a trump one. Where was that trump death clock?

Actually the trump death factor correction comes within about 3% of the overall Canadian death rate.

 

The cumulative case fatality rate is actually worse in Canada than the US:

Just now, mdrejhon said:

That's fair.  Let's get more data over the coming months/year to back up this better.   I agree that we need a lot more data.

The other point I want to point out is it's not exactly that irresponsible to say this, is that at $6 per load, one can scale back the skydvers quite a bit to restore climb performance and then still make a profit.   A 9-person slightly-slower (11-minute instead of 8-minute) climbing Electric Caravan works just fine on dropzone accounting if the fuel-up is only a few dollars (whether $6 or $30).

By 2030 no skydiver-load-scaling-back should be necessary.

I agree that the apparent savings is quite significant. However, I don't think it's as simple as you present it: Yes, maybe you can take fewer jumpers up and still profit on the load. However, that ignores other factors I have already mentioned and simply being revenue-positive on the load is not enough. For example: how many additional planes would a DZ need to buy, house, and maintain in order to meet their current jump capacity requirements?

Maybe with such dramatic savings on fuel it will make sense to work around these factors. However, that doesn't go without saying--you need to show it.

4 minutes ago, mdrejhon said:

They will likely avoid lithium polymer (lipo) for an electric airplane because they can be more explosive.  Most other lithium batteries (the Li-On ones used by Tesla) slowly heat up and smoulder gradually, so it would take more than 10-20 minutes of smoldering before fires.  

That doesn't sound so bad

53 minutes ago, mdrejhon said:

On this point, I disagree it is inconsequential because the mass difference will become much more major as 2020 progresses towards 2030, as explained in three previous posts --

Right, but we were already both in agreement that the batteries will continue to lighten over time, which will bring us closer to feasibility. I don't think a single person in this thread would refute that.

What I'm refuting is the significance you ascribe to this arbitrary threshold of batteries required for jump ops being equal to or less than the weight of a full load of fuel. It's equally irrelevant whether you say "equal to" or "less than" or "equal to or less than".

A relevant statement would be "batteries required for a single jump flight weigh X, and if you replace the fuel in a typically configured jump plane with X, turn time will change from Y to Z."

For all we know, from what has been presented in this thread so far, an aircraft with battery weight equal to or less than a full fuel load may not even be within max takeoff weight. So why is this information useful?

1 hour ago, mdrejhon said:

In a "Designbattery for one skydive + 30min reserve" scenario (between-jump fast-recharging), the amount of battery for one skydive will become smaller/lighter, as an increasingly tinier percentage of a fully fueled load.

Again, we all agree batteries will become smaller and lighter over time, improving feasibility. The fact that this will also mean they will become a smaller percentage of a full fuel load is tangential at best. They will also become a smaller percentage of any other thing that has mass.

1 hour ago, mdrejhon said:

Yes, it will still be heavier than the equivalent fuel for one skydive (partially fueled plane), but regardless, a full or near-full flight with full load of jumpers should be achievable, in this "design for one skydive" scenario.

You continue to hand-wave away the significance of weight on climb performance. This is so important that I think it is irresponsible to keep making such statements without any support.

48 minutes ago, RobertMBlevins said:

That said, my only thought is that these planes might need to have a reserve battery system installed, not a large one, but enough to provide just enough power to get down, in case for some reason the main batteries fail in-flight.

I think it goes without saying that there needs to be redundancy, but I imagine it would be similar to redundancy in fuel tanks--you have multiple of them but they all may see use in normal ops. No real need to have a completely separate module only for use in emergencies.

54 minutes ago, RobertMBlevins said:

just enough power to get down

Not to mention "getting down" won't really be the problem if your batteries go out lol

56 minutes ago, RobertMBlevins said:

Getting imaginative on cutting the gross weight of the aircraft might also help extend range. This is WAY long time ago...but the Germans did the same thing with their old zeppelins. Every single component on board was made with weight of that component in mind. Right down to almost the tiniest detail. 

I don't think this is any different from how aircraft are currently designed, anyway. Weight already matters a lot. If any new tech comes along to make airframes even lighter, electric airplanes will still have to compete with lighter-weight traditionally-powered airplanes using this tech. It's at least mostly orthogonal.

It's one thing that always bothered me about how hybrid cars are marketed: I want to see their fuel economy compared to the same vehicle but traditionally-powered.

57 minutes ago, mdrejhon said:

they need to design electric airplanes to catch fire less often than avgas planes -- for trust of the public.

This condition is necessary but insufficient. When fuel is on fire in an aircraft, there is almost always a firewall between the fire and the fuel tank. You can usually turn off fuel flow and extinguish the fire. A battery fire would be analogous to a fire in the fuel tank, a much more dangerous and rare scenario.

10 minutes ago, mdrejhon said:

I never said that -- you remember incorrectly:

Scroll back to the post, and re-read: "That battery, today, already appear to weigh less than a full fuel load, for some aircraft specifications"

This is an inconsequential semantic difference that doesn't change anything about the discussion we've been having.

Performance of today's Otters at the weights anticipated would be useful information.

1 minute ago, olofscience said:

I think electrification will actually bring this question sooner to aviation - like how electric cars offered advantages in developing self-driving cars. But yes, it is a different question so I'll probably start a different forum post to discuss this.

I'll save my response for the new thread

5 minutes ago, olofscience said:

For reducing weight, I'd even go so far that for a jump aircraft, the pilot doesn't need to be onboard the aircraft. The lift can be flown by AI, with a jump pilot on the ground in a DZ control room ready to take over if the AI needs assistance. Then, they won't need a bailout rig, you'll have room for one more revenue seat, but regulatory wise it could open a can of worms - I might start another topic on this if people are interested.

Maybe that will happen someday, but it's orthogonal to the electric aircraft question.

19 hours ago, Westerly said:

A cloth mask is not PPE. OSHA decides what is and what is not PPE, and an uncertified made at home mask does not meet the legal definition of PPE. If you showed up to a construction worksite which required a respirator and all you brought was a cloth mask made from a bandanna, you'd be thrown off the site.

The R not rate is not going to drop long-term below 1 as long as people are infectible. Right now the projections show that at our current track by March 450,000 people will be dead. If we had 100% compliance with mask wearing 100% of the time, we would have 340,000 deaths. Put another way, even with everyone wearing masks, 340k people would still be dead. That's a reduction of like 30% over what we have with our currently mixed usage. That's good, but not exactly a god send. If masks were truly that effective and legitimately really PPE, then there would be few additional deaths. I bet if everyone wore full, legit PPE including N-99 masks properly fitted, a face shield and a full body chemical suit, deaths would probably drop 100k even lower--just proving that cloth masks are not real PPE. They are band aid in a desperate situation. They help the situation, but you absolutely can still die even if you wear a cloth mask. A vaccine goes far, far beyond that. A vaccine will drastically reduce your chances of death well beyond what even legit PPE can offer.

So what exactly are you advocating for? We've been working on vaccines, but we don't have one ready yet. Are you advocating we take no precautions instead of wearing cloth masks? Because cloth masks are less effective than respirators and vaccines? That doesn't make much sense to me.

1 minute ago, olofscience said:

For the Boeing 787 they couldn't solve that problem - they had to encase the lithium batteries in a heavy steel container to contain any potential fire.

The NASA X-47 Maxwell uses LFP cells which are considered much less of a fire risk than lithium-ion. Elon Musk is also reported to be planning a change to LFP cells for Tesla cars as they're also a lot cheaper in addition to the increased fire safety, but their main issue is slightly lower energy density.

Interesting. Lower energy density by weight, volume, or both?

1 hour ago, mdrejhon said:

...I should also add that the fuel weight lightens as you burn, the battery weight does not.

That's true, and it's important, but what you seem to keep glossing over is the fact that the batteries weigh much more than the fuel they will be replacing. You posited that when the amount of batteries required for jump ops weighs the same as a full load of fuel that this would be a clear inflection point. You stated it as if it should be obvious on it's face that it's true and requires no justification because there would be no drawback. I've been refuting this because the plane would clearly be heavier, therefore there is a drawback and you need to show your work for how you've determined the advantages to so clearly outweigh this drawback. That's really all I mean to refute and the rest of the discussion between us has felt circumferential.

1 hour ago, mdrejhon said:

For the short 8 minutes to 10 minutes to altitude, plane-fueload-lightening is sufficiently small enough (as % of plane mass) that the sheer efficiency of an electric plane motor wins out, by affording pilot more flexibility to milk the airframe/prop settings instead.

Again, please show your work. You seem to be in the habit of just spouting out numbers, in this case 1%, without any indication of where these numbers come from. How much fuel does an Otter burn on a typical jump load? How much does an Otter weigh at the start of a typical jump load? This is very straightforward. If you know this information, why don't you tell us and show your work? If you don't know it, why should anyone believe your conclusions?

This has been a weird thread to catch up on. It seems to have nothing to do with either atheism or morals anymore now that the goalposts have moved so many times. It seems like there are a lot of arguments now about whether or not free will exists, but what I've lost now is: What is the overall point mbohu is currently trying to defend? Is it simply that free will exists? Is anyone refuting that?

I'm always amused with people bring up Schrödinger's cat, as it seems to *always* be misinterpreted. People seem to try to use it to support superposition theory when in reality Schrödinger's entire point in the thought experiment was to show how silly it was. His point was that this theory says a cat should be both alive and dead, and that obviously isn't possible, therefore the theory is wrong. This idea that it was some serious explanation for how a cat could actually be both alive and dead is hilarious and infuriating to me.

40 minutes ago, mdrejhon said:

(re: noisefloor = I meant “lost in the midpoint of the varying time-to-altitude statistics of all dropzones worldwide”. I should not have tried to summarize that into one word, apologies)

For the specific 10%-20% (yes, wholeheartedly unscientific estimate) is based on previous world experiences in other electrifications — electric cars, radio control airplanes, etc.   They drive similar speed and fly similar speed and climb similarly performant at similar weights. In lots of cases, the electrics outperform in raw performance (witness the electrics beating petrol speed records in some domains).  Also, skydivers will become impatient if the plane climb noticeably slower than other planes in the fleet.  10% slower climb isn’t really noticed by everyone in the load, but a 50-100% slower is definitely noticed by the whole load.

But here’s some scientific observations, that actually brings credence to the point I’m making:

The math is a sudden viability line: Change the battery numbers a bit, and things suddenly go from “Can’t meet MTOW” to “I can fly quickly to full jump altitude”.  Given the small envelope of a single jump lift, the fuzz region is actually much smaller than many people think, since a slow-vs-fast climb isn’t that terribly a large watts-hour delta in the Magnix tests (you consume less power but consume longer ...

It is less variable in “power-consumed-per-foot-gain-of-altitude” with electric than with avgas, simply by virtue of the electric motor being efficient at all RPMs.  (Yes, you have to correctly set your flaps and optimal prop pitch and all, to avoid wasting power in an inefficient climb, but once optimal, it is more  balanced than for avgas.

A slow optimal climb vs fast optimal climb isn’t as much battery watt-hours consumed differences as the fuel-consumed differences because of the efficient-at-all-RPMs behaviors that make it easier to dial the optimal climb.  Putting more of the motor’s energy more efficiently into the climb —

Turbines are most efficient at a specific settings, while electrics are efficient at nearly all settings, giving pilot more flexibility to focus more on adjusting the plane’s surfaces to optmium, rather than optimizing the plane to meet the efficiency at the settings of a specific turbine motor.   So, the slow-vs-fast climb matters less since it’s a fixed altitude gain, you’re paying energy a more stabilized amount of energy per foot of gain, you’re paying energy a more equal amount of power for a given altitude gain, thanks to the brilliant efficiency of the electric motor in virtually its entire performance range.   There is still a difference (it’s not linear as one would like), but not as nonlinear as the fuel difference.

If it climbs too slow, you remove passengers or wait for battery tech to become viable.   The power difference of a fast climb versus slow climb from altitude X to Y (0feet to 13500feet) isn’t going to double the battery size.  

The napkin numbers are touchy: A minor improvement in battery tech suddenly allows the electric airplane to have no disadvantage.  

The “fuzz” between not practical and suddenly fully practical (at no climb performance degradation or jump capacity loss), is actually rather a tight twilight zone that may last only a few years, possibly only a year.   So the moral of the story is when the battery gets good enough, it only needs a little more refining to quickly zero out the remaining performance-related disadvantage. 

But a dropzone will bite the ePlane bait a bit before that, i.e. tolerate a 10-20% climb performance decrease to decrease the size of the battery, to gain the other advantages (like major cost savings).  But yes, replace the “10%-20%” unscientific numbers with your favourite low-percentage threshold where somebody bites the ePlane carrot.  I would bet DZOs also won’t bite at 100% slower climb performance.

That’s what we saw happen in other electrifications.  

Anyway, the point being is that the tech fuzz zone between “Not practical” and a “ePlane climbing at full velocity to jump altitude” is actually shocking small, because of the reasons above described.  Improve the tech just enough and — bam — it’s practical without a compromise.   If we’re going to have compromises, it will only be very short-term like removing 1 or 2 or 3 passengers to meet volume/weight envelopes, but only for as long as battery tech improves even a few percent in a “we-only-need-a-battery-for-1-skydive-plus-reserve” scenario.

Anyway, I just heard back from Magnix CEO he’d be happy to be interviewed for the Parachutist article.  Now to formulate the right questions (which may also answer some of these questions too, as well as correct any details in some of my answers).

A heavier plane doesn't just climb slower, it consumes more energy to climb even if we assume 100% efficiency for the entire system. Not to mention there are also other inefficiencies of flight that would not be improved by a change to electric.

I'm not saying this isn't ever going to work, I'm only meaning to say that I don't think the scenario you posed (batteries for x minutes plus 30 weighs the same as a full load of fuel) is the obvious inflection point I think you were implying.

1 hour ago, mdrejhon said:

True, but that may not be a problem — it assumes the lighter motor & other factors don’t fully cancel-out.  

Also — depending on plane — many dropzones don’t always absolute-max throttle their jump ship.  Backing off a bit, especially after takeoff, to a mutually-agreed redline indicator on the dial, for climb performance that makes it easier for the airplane maintenance department & dropzone accountants for avgas consumption.   Some do push it beyond, especially if you’re trying to push loads fast on a busy day, but that can be brutal on the engines of some planes if you’re near the performance envelopes.

In reality, if slower, we are probably nitpicking only tiny percents (e.g. 10% or 20% slower climbs for same plane type) which is within the noise floor of the jump ship variances between dropzones.  And even that assumes we’re using today’s batteries, not tomorrow’s.

Fortunately, from the early tests, it already looks like we’re not going to be seeing 22-minute Cessna 182 style climbs with electric airplanes. 

Sorry... I mean no offense, but this looks like just more hand-waving and a priori statements. How did you arrive at this 10-20% figure and why is 20% acceptable?

I don't understand your point about noise floor... if my Otter is going to become 20% slower than it is now, why should I care that it's still faster than someone else's? 

e: You're also (I think) assuming that an Otter with a full load of both fuel and jumpers will be within MTOW. That may be true and maybe you've actually done the math, but if it is just an assumption it's not a fair one.

e2: Another thing to consider is that we may need to stay under max landing weight rather than max takeoff weight. If something happens and we are unable to drop jumpers, we can't lighten the load by burning off fuel. Not a huge deal because the difference is only 200 lbs, but something to think about.

2 minutes ago, mdrejhon said:

Reduced flight time. The Magnix can climb to altitude faster; the battery difference between a slow climb and fast climb isn’t too terribly major for the current envelopes asked of a 1-skydive battery sizing.

A heavier airplane will climb slower than a lighter one, everything else being equal. This is a hard fact and you can't hand-wave it away. If you are saying a Magnix-equipped Otter at max gross will get to altitude faster than our current Otters at their current weight... perhaps that might be true but that's a claim that needs to be supported and not just stated a priori.

1 hour ago, mdrejhon said:

Extra “fuel” weight is vastly far more than compensated by the massive cost savings. ($300 of avgas cut by 90% to 98% in cost to just $6 to $30 depending on your commercial electricity rates)

That might be true, but it might not be. How much more time will it take to get to altitude with that extra weight? How many more planes will a dropzone need to acquire to compensate for this reduced lift capacity? Will jumpers tolerate the longer ride?

e: Also, it becomes apparent that increased flight time will increase the required battery capacity as well.

21 hours ago, mdrejhon said:

Fortunately, we don't need that much battery weight for electric skydiving aircraft.  We only need enough permanently-built-in battery for one skydive plus 30 minute level flight emergency reserve capacity.  That battery, today, already appear to weigh less than a full fuel load, for some aircraft specifications.

This is certainly impressive, but the proper comparison would be to the fuel load used for skydiving.

21 hours ago, mdrejhon said:

The emergency reserve capacity in a battery also doubles as a battery-longevity-increaser (20-year lithium battery) since you don't want to deep-discharge most lightweight lithium chemistries, unless you have to.

This is a really nice synergy!

17 hours ago, RobertMBlevins said:

I don't know how they calculated something like that. Most everything goes UP as time goes by, except the real-world value of money. When people quote numbers like that, what they don't tell you is that those dollars are 2020 dollars, not 2040 dollars. For example, if you use the Inflation Calculator tool, it will show you that something costing $30 in 2000 would cost you $45 today. 

Unless the money available to you goes up at the same rate, then things actually cost MORE from the money you HAVE available to you. 

Using today's dollars as was done in the chart is the proper comparison, and assuming the money available to you goes up at the same rate as inflation is the correct assumption. That's how inflation works and I'm not sure where you mean to go with this.

7 hours ago, chuckakers said:

Besides, after tomorrow the "real election" will be over. 

I hope you're right!

Just now, olofscience said:

I'm surprised you haven't heard of it - when it made its first flight, lots of skydivers here noticed. Added link: https://www.flightglobal.com/airframers/all-electric-grand-caravan-makes-maiden-flight/138600.article

And the CEO of MagniX who make the motor, is a skydiver. He was interviewed by Pete Allum which I posted here earlier - https://youtu.be/oE1P84Qt2tg

 

Ooh very cool--I took a couple canopy courses with Pete!

18 minutes ago, olofscience said:

You must have missed the electric C208 already flying:

In the UK and Europe the C208 is one of the most common jump planes around. MagniX are going to market it for cargo ops, which is pretty much the exact configuration for skydiving. The 3 DZs near me operate: C208, C208 (3 aircraft), PAC 750XL.

That's really interesting!

8 hours ago, gowlerk said:

The piston engine world may not have the time to wait. 100LL fuel has been targeted for elimination. Diesels have long been touted as the alternative, but despite a few semi-successes the don't seem to be going anywhere. I do believe that if battery electric can be made practical in a Caravan type aircraft it will be relatively easy to adapt it to a 206/182/172 type as well. There are thousands of these out there. Many operated by flight schools and by weekend pilots hobby pilots who don't often travel far. This will provide a tempting market for conversion companies.

Most piston engine planes run just fine on unleaded gas.

20 hours ago, gowlerk said:

That's why I said "practical conversion". 

Right... I think everyone would agree that the change will take place if it becomes practical to do so. What we've been discussing is if and when that will happen.

20 hours ago, gowlerk said:

The may very well be cheaper than rebuilding piston engines.

If that happens then obviously people will convert. I think that's really unlikely to happen in the timescales we've been discussing.

9 hours ago, wolfriverjoe said:

it would make ferry flights really slow, but that's not a super big deal.

It might not, actually. The main reason for varying prop pitch is to keep the engine in the relatively narrow RPM band where it works best. Electric motors have a much wider band, and it may cruise just fine with a fixed pitch prop for the same reason it climbs good with fixed pitch.

2 hours ago, gowlerk said:

They would all switch quickly if someone came up with a practical STC'd conversion. An O-470 weighs about 425lbs including accessories and carries about 100 lbs of fuel for 2 loads.

So what? It's still only going to carry 4 jumpers.

How much will the electric motor plus batteries weigh, and how much will it cost?

These small dropzones are very capital-limited. If we weren't, we wouldn't be running piston aircraft built 65 years ago. It's not like we don't have better options available if we had more money to spend.