Jets... on!

These guys (and just two of them) have broken cover and, so far as I can see, are the first to offer a personal air vehicle for sale under Part 103 (US Ultralight Classification).

Actually that's not strictly true, as you can't walk away with one today. You can though transfer $14000 toward the eventual $49000 in order to occupy one of the first dozen 'build slots'.

Best thing about it is that people already find the cost reasonable, at least compared to the projected retail price of competing air vehicles.

The first production cars and aeroplanes also cost a tidy sum (and I once calculated Sikorsky's original production helicopter cost the equivalent of two-thirds of a million dollars, despite performance and reliability being lamentable by today's standards).

But good news in view of the non-appearance of working models including my own.

Which I'm working to fix.

Diego Maradona RIP

Surprising coming from an Englishman, but he may well have been the best footballer ever. Took my son to Asif Kapadia's documentary on the player last year, and glad I did. Only when you see the footage from the sidelines do you appreciate just how often he was targeted by opponents, only to get straight back up and recover the ball.

Lesson for us all in that?

Droning in the Dark

Fuck, this drone technology's a pain in the ass.

Drive out for another ground run ~ toute seule ~ imagining I've covered all bases. Even to the extent I blank out the windows the better to see the laptop's screen

10,000 hours of jumping into airliners and only ONCE them failing to calibrate the IRS's during the first ten minutes, and that due an unduly hurried pushback on my part.

But the horizon refuses to report level and I cannot find the calibration for the life of me. And so after around three hours of trying, I resort to the flask of coffee and a tuna sandwich. Make a picnic of it whatever, I say.

The only silver lining is that the airframe, despite my pledge to beef it up, is suitably resilient. Dragged at high speed on the trailer around the country and slid off and back on and jacked up here and there with wooden blocks and no murmur of complaint.

Only one thing for it and that's to power the thing up in the garage whilst nailed to the trailer and go through the how-to videos before we emerge again into daylight.

The lockdown gestapos would be delighted.

Point of View

I watch the Russell Crowe in his latest film, Unhinged. (That's the name of the film, not the way I was watching).

Not a TV programme or film goes by nowadays without aerial shots taken from drones, and yet the providers of the same in this case are credited on the IMDB database, but not so far as I could see on the film itself.

This is despite literally hundreds of credits, stretching practically as far as the guy who collected the cappuccinos each morning.

Every civilisation underrates whatever is changing it from the outside... and ours is no different.

Vince Reffet

It was Otto Lilienthal who said "Small sacrifices must be made" and he was just one among many throughout the centuries and in diverse places to have sacrificed himself to the cause of truly personal flight. Whilst nobody pursuing such a quest is absolved from any number of sacrifices, it is characteristic of such people as these to diminish the scale of this... its greatest.

Skydrive(r)

Beside their sizeable investment in Joby Aviation, the maker of the world's best-selling car in the shape of the Corolla ~ Toyota ~ is backing this home-grown development. Good news from my point of view by virtue of the fact it's an octocopter, so that along with the Blackfly it gives the lie to the notion that any more than eight motors are required to assure the safety of electrical flight.

Spread My Wings...

... and fly away?

Been a depression blowing through after discovering Friday that the GoFly Challenge is now to be a first across the (on)line affair, for which we're ill-suited in the UK during the lockdown beside the ponderous avenues afforded test-flying by the Civil Aviation Authority.

Nonetheless design of the 'DRONE has been an evolutionary process from the outset, forged by repeated fabrications on my part combined with insights, the best of which seem to occur at three in the morning.

Like this one, for example, which I add to the IP portfolio, as of.

Advantage of which is that two separate yet compact quadcopters might be combined ~ the green at foot-level and the red at waist-height as per the current prototype ~ to create more lift altogether. At the same time, with cantilevers extended to two metres the propellers are pitched at a safer distance altogether from my own tender frame.

It's been a must in terms of sheer lift since I adopted lighter and cheaper motors, while providing for a more substantial leverage to facilitate flight-control.

All lies beyond GoFly's allowable dimensions, but notwithstanding my own love of compactness the team is united in the belief that we need the extra to assure the safety of piloted operations.

Still leaves the current prototype available to the challenge, beside the promotional video that we were endeavouring to address just prior the current confinement due the Covid-19 pandemic.

Nonetheless the working parts will likely be stripped out for re-use in a (fifth) marque as per the outline seen above, pending a decision on re-financing through crowd-funding if not my own billions... of mites.

So while things remain up in the air, there's every chance of staying there.

LM(A)GM

I tune in thereto, and fascinating it is too, touching as it does upon drones in general and heavier drones like mine in particular.

Until recently, regulators worldwide had little or no interest in radio-controlled modellers and vice-versa. Then technology got to the point when large models could be built (and which modellers do not want a bigger member... ship?), around the time that multicopters became a nuisance to airline operations.

I've seen both sides in the form of spectacular displays of turbine-engined models on one hand, and a drone not a hundred feet removed from the Airbus I was flying on the other ~ and at an altitude of around eight thousand feet.

What I witnessed at the AGM today from its online host was the convergence of rules once only applied to airline operators increasingly being applied to everyone else with anything that leaves the ground in any shape or form.

It has been suggested that some time in the near future we shall all be monitored at every point in our lives, finally bringing to life the scenario imagined by Orwell as occurring by 1984.

What is increasingly apparent is that in a world of drone-delivery and three-dimensional taxis, that remit will be extended to every form of flying robot out there, which is what all aircraft will be once humans are removed from the equation (except as passengers).

With their social links and those between 'man-and-machine' I feel radio-control modellers may be going the way of the dinosaurs.

Gone Fly?

Gents,

https://www.herox.com/GoFly/update/3594

This arrived Thursday but I didn’t get around to reviewing prior today.

In brief, what GoFly are saying is “First to send us a video of yourselves flying around for 20 minutes in a vehicle that fits in a 2.60 metre bubble ~ and if we observe same on a given date ~ then the $million’s yours.’

This leaves us looking like Macmillan on the day Hitler told him they’d built a Luftwaffe and he was on the end of it…

And having read eVTOL news this week ~ site currently crashed coincidentally or not ~  Dragonair seem good to go.

Reasons being:

(a) they’ve Part 103 approval from the FAA and are free to fly any time

(b) we’ve no equivalent and a CAA deemed unsuited to purpose by the AAIB

(c) …who allow NO radio-control tests beside a snail-paced Experimental category

(d) the weather in Florida is ideal for flying, and shit as ever in the north of England

(e) they’ve a do-able drive to wherever GoFly decide the observation will take place

(f) we’ve the Atlantic to cross

(g) they’ve the required batteries

(h) we don’t and the extra weight would require a motor upgrade to those they use.

None of which is to begrudge their efforts, as I’ve always considered Dragonair a front-runner since seeing the footage, the team and the prototype in action.

Whether it’s a vehicle for everyone however is a moot point ~ Mariah being the only one to take to it like a duck to water, having taught people to fly water-jet packs.

Am also aware that luck is what happens when preparation meets opportunity!

My immediate question would be (and I’ve copied in GoFly) whether the observation would take place in the US, which would likely be the final nail in our coffin.

Having said all that, it’s been a blast, the build experience has steered us toward saleable product, and of course the organiser (herself) retains an interest in the company.

Great shame not to be able to meet up with them all again though, so as ever it's about appreciating whatever each day brings… and with sincere thanks for your support.

Colin S. Hilton

Teledrone Ltd.

In response to new GoFly rules that are like standing at a trackside, firing a gun and declaring the race on no matter how far they've all got... I've placed my bets already on Team Dragonair!

(Well) Grounded?

Stepping away from the vehicle from time to time does wonders, and in the wake of the abortive field-test of the TELEDRONE on the eve of lockdown I repair to Istanbul to lick my wounds.

The project needs monetising at some stage, and sooner rather than later. The conventional path for jet-pack developers (and more recently those developing electrical UAM solutions in the US) is to leverage prototypes by pitching them for race series, or providing instruction, or appearing at events.

Our former team-member Martin Andrews once spoke to the originator of Gravity's jet-pack, who was struggling for realistic applications at the time. No longer, however. He's frequently in the news storming naval ships or 'rescuing' mountaineers when he's not providing entertainment at Facebook jamborees... and that's when he's not providing tethered flights to acolytes at £5000 a pop.

Ditto the Artist latterly known as 'Jetman'.

In terms of regulating the 'DRONE as it stands, for a personal flyer, it's a practical impossibility in either the UK or Europe, which are geared to multi-million dollar developments... which quite suits. The UK CAA for example rarely if ever prosecutes airlines ~ not least due their refusal to refund flights cancelled due pandemic ~ for the simple reason once again that money talks.

In conclusion, whilst I could pursue a manned test-program under Experimental classification this side of the Atlantic, one is tempted to ask what would be the point? Subsequent to one such tile-limited program, thereafter the type would have to be certified at a cost of a large fraction of a billion dollars. No wonder then that all they can produce from within their UK government grant-funded Innovation Hub by way of example is a multi-million dollar German company in the form of Volocopter.

Reminds of the comedian who said the Germans build the best executive cars, the French build the best family cars, and the British build the best Japanese cars.

Meanwhile my efforts to obtain approval to test-fly the prototype as a radio-controlled model via the Large Model Association is stymied by the fact that the AAIB (UK Air Accident Investigation Bureau) have effectively put the CAA on the naughty-step following their mis-management of events leading to the (repeated) crashing of Airspeeder's prototype at a public-event. Which was okay for them, in view of the fact they were flying home to Australia next day having shat on our door-step instead.

Accordingly the only feasible product I can envisage selling on home turf is a hovercraft, defined by Google amongst others as 'a vehicle or craft that travels over land or water on a cushion of air provided by a downward blast'.

I never did get a reply from the CAA to my open letter regarding:

https://teledrone.blogspot.com/2020/10/open-letter-to-uk-caa_1.html

... but there's not doubt they did eschew responsibility for 'air' craft operating below a height of ten feet many years ago.

In fact I recently queried a vacancy at Hovertravel's ferry service between Portsmouth and the Isle of Wight in the UK... the last such in Western Europe, apparently. They used to use pilots certified by the Civil Aviation Authority (CAA), whereas now they use? Master mariners, who are officially steering 'vessels.' 

As a consequence of all which I draft that outline seen above on a shopping pad (recalling that similar sketches have actually turned into flying machines).

It shares the same platform as every previous prototype, the original design being wholly flexible in the way, say, Land Rovers and Jaguars share a common chassis (or Renaults and Nissans).

May be mileage yet in this flying carpet. 

GoFly Update

GoFly was and is the Boeing-sponsored competition that inspired any number of efforts around the world to design and build a compact form of personal air vehicle (PAV). The Vertical Flight Society recently summarised the ongoing progress of the twenty-one teams appearing at the fly-off in California in February of this year (2020), and for my own benefit if nothing else, I have condensed that further.

In view of the Coronavirus pandemic whose worst effects were starting to be realised around the same time, it is worth reviewing the prospects of those teams most invested in the competition, if only to take stock of the prospects for electrical flight in particular at the smallest scale.

Most of the investment around the globe has been concentrated to date upon the development of wholly larger 'flying taxis'. Nonetheless as can be seen from the interest in jet-pack technology ~ and as seen here, electrical forms of personal elevation ~ their may yet be a profitable niche lying between heavy drones on the one hand, and these multiple-occupancy types.

As seen in the previous post, it was single-seat step-through motorcycles that most democratised motorised forms of terrestrial mobility, and there is no reason to believe that single-seat types might not pioneer a similar path to the skies:

Aeroxo's AVIABIKE from Russia, with a base in Riga (a place I've been in connection with flight training). Their tilt-rotor industrial drone does pre-date their piloted project for the challenge, and from the website it appears this is where the current efforts are concentrated, if only by way of a faster route to market given a straightforward means of certification. This is a frequent path for even the best-invested firms to take, Volocopter themselves being recently side-tracked by a smaller cargo-carrying version.

Canadian academic Gary Gress continues to test-fly his ATHENA scale models in preparation for transitional efforts into forward flight, having undertaken any number of hover-tests ~ which are always the easier, occupying as they do a smaller space altogether. Curiously the effort is incorporated just along the road from me in Preston in the UK, and had I known that sooner I'd be knocking on the door and chewing the vertical-take-off cud.

Another Canadian project from among the 'groves of academe', development of the latest prototype PKOK. This is an abbreviation of peacock apparently, which they might want to consider in view of the fact that the bird can barely fly. Though progress continues, albeit admittedly stalled to some extent by the effects of the Coronavirus and the inevitable delays associated with forms of government funding.

Dragonair's third AIRBOARD prototype warrants an extended entry all of its own beside the text of the VFS update, and I can see why. As they point out, they provide the bulk of video-footage of practical personal flyers, and without a website YouTube appears to be the principle platform. Behind the scenes there is interest from investors and invites to corporate events as they work to build three prototypes for the sort of campaign successfully pursued by the various jet-powered personal means of flight.

Another personal effort from a well-qualified Austrian entrant, the EDEA quadcopter is powered by hybrid units comprising a Wankel engine combined with four electrical motors (and there are four of these combination units powering the quad). This is therefore a complicated mission altogether, and unsurprisingly the project awaits further funding in the form of state-funded grant finance. In view of the travel it was the power-units that appeared in California in lieu of any prototype vehicle, I recall.

Nepal-based Garudeus (named after the oriental god of flight) continue work on their single-seat flying trike, and are based in California so far as the web presence is concerned, where they are allied with the M4 Engineering consultancy that provides paid-for prototyping and testing. The project itself is like so many others involved in the GoFly challenge in being led by a Singapore-based principle from among academic research quarters accompanied by a team of VTOL acolytes. Sounds like a cult, but isn't...

The Gyrobikers GYROPACK is an intriguing concept from a Spanish-based team, and therefore looks like a flying parasol. It is however a flying parasol with 'wiiings' as an unnamed investor stepped in at the end of 2019 to support ongoing efforts toward a prototype ~ a venture in which sizeable aviation group SAFRAN is apparently involved. This is unsurprising, as this (especially with its pneumatically-driven overhead fan) is no garage-project.

Team JAYU comprises a couple of young guys from MIT since working for companies involved in the broader technology, and there appears to be no further news regarding those sub-scale prototypes last flown ~ most successfully ~ at the GoFly event. It could be the project is proceeding under wraps (as did others like Volocopter, periodically), yet a less popular suggestion for the conspiracy-theorists might be that the founders got pre-occupied by the day job: especially given the pandemic's affect on every job.

'Phattony' of flying-circus fame continues the development of his electrified Harrier VTOL jet, with flight-testing scheduled for the Spring of 2021. Whilst there is a website it would appear the bulk of the news of his progress stems from among Facebook pages. A decidedly ambitious quest, I do fear that while the power required is not beyond electrical means, the size of battery-packs may yet be, given the Harrier's efflux was nearly twenty times less efficient than that of a conventional helicopter's rotor-disk.

Whilst named after the world's lightest gas, the HELIUM project appears to have sunk without trace. Founded so far as I can tell from among student researches, it could be that the projectees have literally grown up and gone their separates, as the Facebook and Twitter feeds have been discontinued along with the website. Always a shame, although the concept itself is widely anticipated as here at https://www.youtube.com/watch?v=raVzAjMgLE8

The RAVEN stems from a guy in Georgia, who not only matches the typeface used here, but is among the most interesting places for a project to have sprung from. Impressed by the simplicity of his original project as it appeared at the challenge ~ an inflatable parawing powered by modest electrical motors above and below ~ I think he's mistaken in having scaled the notion up too soon. As a possible consequence he appears short of funding for the current.

'Team rFlights' rWING appears to have continued to pursue a life of its own, although not necessarily in the more material form in which it appeared in California. An ambitious alloy airframe used together with a gasoline engine is something that the likes of Bell struggled with back in the X-plane era of the 1950s, which is why the project looks to have advanced only in digital form since. The team itself is sourced openly, and as such has worked on the Elon Musk hyper loop competition. Watch the space, don't hold breath.

Another project to have succumbed to the passage of Old Father Time, the RMIT University team from Oz have since graduated, and with luck will be in gainful employment instead of throwing wads of Australian dollars at the kind of project that I know from experience always wants for more. Again, given the logistics, what they displayed at the event was anyhow a sub-system in the shape of co-axial propellers (not unlike my own in so far as they mount upon separate spars instead of a common). Good job, guys!

SCOOP was a father-and-son team who displayed a scale model at the fly-off, and very nice it looked too. Son is an aeronautical grad who seems to have debunked from South Carolina to Maryland where the eVTOL landscape is apparently greener. Aside from this there does not appear to be a great deal of news here, and perhaps this is unsurprising as the airframe itself, whilst decidedly comely, is doubtless an expensive piece of equipment to manufacture even in prototype form.

Another project that appears to be flourishing in digital form while not appearing to have gone beyond the considerable flight-testing success at half-scale evidenced prior to GoFly's challenge. That said, the team at least then comprised thirty students from Delft University, who between them gave the accommodation at NASA Ames a fraternity feel if nothing else. There website is also Sponsor Central, featuring as it does any number of global firms who are clearly a soft-touch when it comes to fresh-faced pleas.

Am going to have to declare an interest, but team TELEDRONE as appeared in California is practically unchanged with the exception that the pilot had to be replaced due loss of interest. In fact as all of the above will doubtless share, sustaining interest in ventures such as these is that much harder than getting up to go to work at at someone else's behest ~ which is comfortable if on occasion the less satisfying. It's taken a long time to get it looking like this and wired as an octocopter, but it looks the more future-proof for it.

HARMONY Aeronautics has been spun off from the associated development at Texas A & M University and they are not wrong when they say the larger the rotor, the more efficient the power. As a consequence they appear to have trod the well-worn path of licensing a technology sprung from university to all-comers. This in fact is how technology related to MRI scanning and Monoclonal Antibodies (of such use under the current Coronavirus pandemic) saw the light of day in the UK.

The great advantage these guys have is that they've a day-job that pays the bills whilst they develop such projects on the side as this. In fact this is among the reasons so many of those teams making the final cut at GoFly stemmed from university-funding, or else teams like this (or Dragonair with a water-sport background). No obvious progress as regards this iteration in particular, but as it is among those with the most solid foundation, it will doubtless be rising like a Phoenix post-Covid-19.

Close to our own hearts given the generous assistance afforded us at the February 2020 event, besides team JAYU, is the progress of Pete Bitar's VERTICYCLE. Seems from the website and recently-released video that more attention ~ as I did suggest myself ~ has been paid to completing the electric jet-pack. As a consequence of this there appear to be alternative uses for the ducted fans (like a link-up with RANS) as Trek Aerospace have long-since found.

ZEVA's air vehicle suffered a setback when the manufacturers of their 25-kilowatt motors folded, requiring a re-equipment along with a doubling of the required voltage. I know from experience the time required for each re-iteration, though there is no further news on the resumption of flight-testing supposed to have taken place in July just gone. At the same time (and uniquely among so diverse a selection of teams) their efforts have been diverted into production of PPE to address shortages due to the pandemic.

In conclusion, while progress has been decidedly patchy, it would not be surprising in view of circumstance. It could also be that among the original 854 teams worldwide (else new entrants beside), more progress is being made elsewhere.

Notwithstanding flying-taxi firms fortunate to have benefitted from pre-pandemic investment, however, it remains the case that those designs that are most easily converted from prototype to beta-product are the ones most likely to stay the course.

For at the end of the day, you cannot beat the physics.

Honda 50 Cub

One reason that I'm convinced there's a market for an inexpensive single-piloted helicopter of the sort I'm pioneering: the Honda 50 Cub. It's well turned sixty, effectively unchanged, and still in production after sales of 100 million units plus.

"Best-selling cars" don't come close, and in fact the term "Best-selling name-badge" is better applied to the likes of the Golf and Corolla. Accordingly the closest you come to continuous production is the VW Beetle (and even that changed moreso than the above in appearance), and that has been outsold by a factor of four by the unpretentious Cub.

Reasons for its original popularity include the Japanese love of the miniature, a condensed road matrix and a love of home-delivered noodles (which is why it could be ridden with one hand as well as with two).

Above all, however, for a society transitioning from foot or rickshaw to bicycle and beyond in terms of mass-manoeuvrability, it has always been the affordable choice.

(China might be considered the only society to have skipped the phase and transitioned from pedal-power to automotive, but that was only possible because of an oven-ready manufacturing previously established elsewhere, along with a global network of trade).

Accordingly, as movement in three dimensions becomes a possibility, it will neither be confined to the multi-million pound models littering the eVTOL databases, and nor will these types be among the best-selling.

I would be more than happy to be looked down upon as among the lowest form of aviation, so long as I am out-selling every other in unit terms... In this venture, money (along with physics) talks.

There are jet aircraft out there too that have seen service for nearly seventy years beside steam locomotives that saw out a century ~ in view of which a month's lockdown for a pandemic is not necessarily an impediment to the development of iconic types. Or that's the hope, anyway.

And my own first means of motorisation, all those years ago?

Honda P50 and PC50 mopeds... followed by the self-same 50 step-through motorcycle.

Baptism of Fire

Picnic at Hanging Dock

’Twas the eve before lockdown ~ that annual event in the English calendar ~ and I decide upon an operational sortie, or form of ‘dry-run’ in advance of the inevitable CAA approval for thoroughgoing flight-tests of the radio-controlled TELEDRONE octocopter. For this I’m joined by a licensed drone-pilot and Martin Andrews’ heir-apparent, and convene upon a local farmer’s field of lawn-turf.

All of which proves the value of real-time experience with a full-scale eVTOL capable of levitating a full-scale Colin Hilton. I had intended upon a preparatory this kind of got lost among the Alan Bennett box-sets. Shortly after gracing the hallowed-turf, therefore, on opening the screen I learn that (a) it is too bright to see the screen (b) thus cannot tell when it is on and when it off. As the wifi has been left on too, being a Windows computer it spends most of its waking life trying to install downloads to the operating system. And whilst this goes on, or rather doesn’t, I get a call from an irate farmer to say I shouldn’t really have driven across his super-sized lawn without agricultural balloon-tyres.

As a consequence, I am unable to persuade Mission Planner to connect to the drone, or vice-versa, without which we cannot see how much battery power remains available to run the motors without draining them completely… which renders LiPo battery-packs useless, and which itself is much like burning €500 notes for a hobby. The drone does have an alternative means of signalling this condition, and this is to drop out of the sky like a fifty-kilo sack of potatoes.

Am conscious that the drone-pilot has a day-job to pursue, and money to earn instead of frittering away like this. And so I remove the Jimny to the nearest exit point without passing ‘GO’ and sit on the trailer consuming what Northerners call our ‘snap’ or else a corned-beef roll and a flask of tea.

Thereafter I repair to the electrical engineers homestead, as he is the only one of the team knowing anything about Windows, and how to rectify our failure to persuade the applicable ‘driver’ to recognise the aerial plugged into the USB port. This he persuades it to do in around ten seconds flat, and I make a mental note to make sure he’s on a short lease next time around.

The joy doesn’t end there, for as I am explaining the importance of cross-checking the electrical connections like the cabin doors on an airliner, I promptly connect two fully-charged battery-packs together so as to create s form of plasma discharge bubble that encapsulates my left-hand. The reason nobody was close enough to do that all-important cross-checking, too, was that nobody wanted to be anywhere near those 32” carbon-fiber propellers with around six horse-power each to play with.

This was almost enough to put me off, and while the damage to my own set of digits looked spectacular, ’Twas but a scratch as the cavalier without the leg said at the Battle of Waterloo. The said engineer suggested that I not post the pic on the blog, but like the great parliamentarian Cromwell would say of his portrait, it must be warts-and-all or else nothing.

For no lesson goes unlearned, and connecting the wrong ends of fifty volts is something, like life itself, that you only do once. I also make a mental note of using only fourteen-cell packs in future, instead of pairs of seven- which have to be joined in series so as to meet the required voltage.

It puts me off only momentarily however. I was once most of the way to Southampton at around eight-thousand feet when my (single) engine appeared to have iced up for reasons best known to itself, and I had to exit the airway and glide all the way to Luton Airport. Even next morning I was loathe to get back into the saddle, but you have to.

Anything you walked away from cannot have been that bad, they used to say, though as you get older you cannot help feeling that anything that left you alive cannot have been all that bad either.

Worst thing about the day though is the fact I miss my Kundalini yoga class just prior the second national lockdown.

Cartoon explosion-effect

Lock Downer

The UK government announces (prematurely due an inevitable leak) that November is to be deleted from the calendar, adding to three months of lost productivity throughout the Spring.

I think the modern world ~ just when we thought we'd conquered Nature along with all else ~  is ham-strung by a fear of death and an aversion to every conceivable risk.

Ironically this might accelerate the death of what it means to be human, moving ever more of our daily affairs online and into the hands of robotic and artificial means of intelligence.

In the pursuit of eVTOL, while we may not want to wait for the government, we want even less to be waiting on authorities that will inevitably use the excuse of a pandemic to strangle it at birth.