Yes but your car engine isn’t producing 375 hp at 2200 RPM.
Airplane engines are designed for maximum hp at very low rpm’s.
But that kind of makes LSL Guy’s point: There’s no reasont to run an engine at such low RPM. Modern aero engines like the Rotaxes use gear reduction so the engine can run more efficiently. Getting those certified under the old rules would have been very expensive.
what’s the TBO time on a high hp rotax?
Are SST really coming back or is this just a publicity stunt?
2,000 hrs.
I was wondering the same thing. I mean, didn’t a whole bunch of airlines “order” Concordes back in the day, too, only to cancel those orders without ever taking delivery?
I would be really cool if SST did come back, and because of that really want Boom to be successful, but I remain skeptical until one actually flies.
In other news, there’s an update on the jumping pilot we were discussing a few weeks ago:
And a preliminary report from the NTSB:
https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/105636/pdf
Wow, it makes it sound like he was so upset about damaging the plane that he jumped out of the plane.
SSTs are potentially coming back. The tech is here now to make one that works for trans-oceanic premium passengers, that isn’t too noisy, and given a green source of fuel, green enough for modern sensibilities.
The obstacles now are more regulatory than engineering. Plus raucous opposition from those Greens who are against anything new that burns any sort of fuel.
@Magiver:
Agree about the RPM difference. Gearboxes are the modern answer to what was, in 1955, an insoluble problem given the weight and reliability limits of the time.
Again I really think the big piston singles & twins will be retrofitted w electrics before they’ll be retrofitted w a modified car engine burning autogas.
Ref the jumping FO. … Thanks. Great find.
That NTSB preliminary has a lot more detail than the one they released the day after. Still leaves the open question of whether he really actively intended to jump, sorta let it happen passively, or it was the second big mistake he made that day.
I suspect no one will ever know for sure which.
From the article:
This is still a paper airplane. It underwent a ‘design overhaul’ just a few months ago.
I don’t know if it’s a scam, but it’s certainly very high risk, and the odds of them hitting those schedules are next to zero.
Take the Boeing 787 - a completely conventional, subsonic aircraft designed around proven engines and systems, being built by a company with a long history of bringing new aircraft to life. The 787 project started in 2004, and first deliveries didn’t happen until the end of 2011, about eight years later. And that’s pretty fast for a new jet.
This ‘Boom’ company has a radical supersonic design, claims it flies on ‘green’ fuel, and has to build a manufacturing infrastructure from scratch. And yet they think they can deliver these things faster than Boeing managed with the 787.
Also, the 787 project cost $32 billion dollars. These guys have apparently raised $270 million. If I were offered a bet, my money would be on this project failing, or perhaps having been a vehicle for hoovering up investor capital and government money with the actual airplane being a lower priority than pretty CGI renderings and investor paks.
I hope I’m wrong, but there have been a large number of radical new aircraft designs being promised over the last fifteen years. Air taxis, flying cars, supersonic jets, electric craft of all sorts, you name it. We’ve talked about a lot of them here. Not a single one has been certified. Most of them are already out of business. A couple are still being worked on.
The Eviation Alice was an electric aircraft with a radical new design that included a tail-mounted propeller, taildragger configuration, and electric motors with propellers on the wingtips. These innovations were its big selling feature, despite lots of people pointing out the obvious flaws with them, and problems with their claims for range, battery weight, etc. Still, they got orders for dozens of them.
Then the non-flying prototype accidentally burned up, and suddenly a new version was being made that no longer had the tip motors or the tail motor, but an utterly conventional tricycle gear, T-tail design with two fuselage mounted motors. And suddenly all the specs were worse as well. The battery has 15% less capacity and is heavier, the speed slower, range lower, etc. And it still hasn’t flown. Started in 2015.
We have been in an asset bubble world since 2007. The rich have been looking for places to invest their money, and that drives stuff like this. Hyperloop is another example.
It works for me to assume that every fanciful new airplane with pretty CGI renders announced from a new company is bullshit until a prototype actually flies and exhibits the specs claimed for it. Sadly, that strategy has been correct almost every time. Building and certifying a new commercial aircraft is very hard. Trying to do it with a radical new design is harder. Trying to do that with no prior experience and limited funding, well… I’m sure some of these companies are sincerely trying, and others are just vehicles for attracting money.
Either way, failure is the way to bet until you actually see something flying. Static displays of hollow fiberglass shells do not count. In fact, if I see a company building fiberglass shell versions to take to trade shows and fly-ins and such I downgrade the seriousness of the company and assume they are just trying to attract money.
Great set of points there @Sam_Stone. I too was greatly dismayed a couple months ago when Boom unveiled their “complete redesign”. My only reaction was “Were you lying to us then or are you lying to us now? The two configurations can’t possibly both be truthful.”
FYI we’ve got a more or less dedicated thread on these various supersonic wannabes over here:
The last few posts are all about the latest Boom news.
As to the 787's teething pains (and now ongoing growing pains) I'll quibble a bit.
The 787 as a machine was far more different under the paint job than it at first appears. It is quite a radical advancement over the immediately previous 777 in many ways.
And a LOT of the troublesome innovation was not in the materials / hardware / software of the machine itself, but in the industrial arrangements between all the companies that were building the chunks that go into it. A LOT of crappy management wishful thinking went into all that business and accounting chicanery. Much of which has since come home to roost.
But your larger point is still well-taken. Boom is trying to do something real hard, real fast, with rather little money. That’s usually a recipe for failure. Whether by design as an investor fleecing mechanism, or due to pure wishful thinking by a charismatic and hopelessly optimistic dreamer.
I like to think it’s the optimistic dreamer rather than a scammer, but there are both types out there.
The Moller Skycar has been in development for 40 years, and has been ‘six months away from untethered flight’ for at least 20. Over $100 million has been invested, and the thing still hasn’t flown in anything but a tethered hover. And yet, Paul Moller is a serious engineering professor and as far as I can tell actually sunk that money into development and believed in it. The money finally ran out in 2015, and as far as I know the project is dead.
Moller was taking pre-orders in the 1990’s.
Further on Evation’s ALICE …
Tomorrow’s issue of Aviation Daily (paywall only) contains an article stating that the prototype ALICE has just been moved to Moses Lake WA in preparation for first flight. Taxi tests have been ongoing back at the factory in Arlington WA.
Whatever it looks like, it’s not a paper airplane anymore. Will it meet the current set of advertised specs? We shall all see soon enough.
Exciting times in aviation.
Quick question…when they advertise (in your link) a max range of 440NM does that include extra fuel/battery for diversion and reserves or do they mean that’s the furthest it will go with no regard for safety margins?
(Note: This will apply to any advertisement for a plane and not just this one.)
That’s with “IFR reserves” which is a pretty ambiguous term. I’d guess 30 minutes but it could mean more. If it’s just 30 minutes then your 440NM will often have to include flight to an alternate (diversion) airport as well. I’m not sure where the regulators are at with “fuel” planning for electric aircraft.
It’s also with no payload so it’d be interesting to see how different it is with payload.
Here’s CNN’s update on the jumping copilot:
Late ETA: Oops. @Elendil_s_Heir slipped in while I was bloviating. This is following on @Whack-a-Mole’s comment 3 posts above.
As @Richard_Pearse said, it’s definitely NOT 440nm to “props stops”.
In the US, “IFR reserves” for conventionally powered airplanes means 45 minutes of endurance at planned cruise fuel consumption. I do not know of any different standard for electric airplanes, but there might be one. The inherent reason for the 45-minute endurance is to make up for flight planning vagaries, navigation vagaries, ATC vagaries, and the possibility of an aircraft malfunction or a go-around for non-weather reasons. All of which reasons are equally applicable to electric airplanes. Leading me to suspect there isn’t / won’t be a different time requirement for them. Note this is about “airplanes” only. Electric helos, E-VTOLs, and other weird hybrids will doubtless have different standards, just as conventional helos do.
For sure ALICE’s marketing computations do not include time / distance / fuel / power to reach an alternate, as those could be any variable distance away. Said another way, the 440nm would be the maximum range you could go to a destination on a nice day. Or on a crappy day 440nm would be the farthest you could go to an alternate having gotten there by way of a failed landing attempt at the destination.
Notice also they say “no payload”, so this is perhaps better termed the “ferry range” of the aircraft. It is emphatically NOT how far one could plan to fly in scheduled service with a load of people and/or freight.
[mild digression]
-
However ...
As a general matter in all aircraft, range decreases with additional payload. It’s also the case that conventionally fueled airplanes start out heavy with fuel and get lighter as they consume fuel progressing to the destination. So the so-called “payload fraction” of total weight goes up over time, while the “fuel fraction” goes down.
Electrics are different in this. Fully charged or fully discharged, batteries weigh the same. A consequence of this is the weight factor corresponding to “fuel fraction” is a constant, and a big one. A consequence of that is the “payload fraction” is always a smaller fraction, which means it has less leverage on total fuel/energy consumption. Said another way, range is MORE sensitive to payload in a conventional airplane and LESS sensitive to payload in an electric airplane, all else equal.
So pilots’ or managers’ general intuition about the likely difference between “ferry range” and “practically useful range with a profitable load” are probably a bit pessimistic vs reality. We’ll all learn more about this difference as real-world industry experience with electrics begins to build up.
Lastly, 440nm is rather short compared to the broadly comparable
Which various models have ferry ranges up around 1700nm+.
It’s well-understood that at least at first, electrics’ ranges will be pitiful compared to their conventionally fueled competitors. It’s also well-understood that in many, many use cases for many, many different operators, the vast majority of flights use only a small fraction of the aircraft’s max range.
The 737 I drive can be planned for about 7 hours maximum gate to gate in airline service with typical loads, reserves, yada yada. Eyeballing through my recent logbook, I think about 2.1 hours is a good guess for my personal average flight duration. And even that is flattered by the large-ish fraction of longer overwater international I do across the Caribbean. I’d venture a purely domestic USA 737 driver would average closer to 1.7 hours per flight.
So the fact the ALICE has a 440nm ferry range and the King Air 200 has a 1700nm ferry range is not as restrictive a difference as it might first appear.
Here’s a good overview of the state of electric aviation from the National Renewable Energy Labratory:
In that paper they say the Eviation Alice has a 440nm range with a 45 minute reserve. So if we assume it would fly 150 nm in 45 minutes at best efficiency, that’s a total range of 590 NM on an 820 kWh battery.
If the battery is charged to 100% and allowed to drop to 0%, that’s an efficiency of 1.4 kWh/nm… That sounds high for a 6350 lb aircraft, but not outrageous. I wonder if they are including battery and cabin heating requirements, given that this thing will be flying above 20,000 ft.
But we are definitely getting into feasible territory for some short-haul needs. I think electric is especially promising for flight training, where most flights are an hour or less. A small 2-place electric training craft could really lower the cost of learning to fly. Lower mainenance, much lower energy cost, simpler to fly. What’s not to like?
That’s not bad. don’t know if I trust the gear reduction system but that’s a good number. I wouldn’t mind seeing more metal around that housing.
I’m not hugely interested in an electric plane at the moment with the current battery technology. I would like to see the celera 500L make it into production. It’s scalable and could handle different engine types.