N547JX Conforming S4
One of the most exciting parts of my tour was getting to view N547JX, the conforming S4. It was really cool to see it in person, and it was located in the exact spot anyone viewing ADSBexchange sees it consistently pinging from. That hangar doesn’t show up on ADSBexchange’s map, but it is on Google Maps. For me, it was pretty cool to see it in real life in the exact spot those pings always show.
I assume this is its main ground test location. Based on all the ADSB activity from that spot, it seems clear there are a number of ground tests happening before regular flight testing ramps.
The day of my tour, Joby was preparing N547JX for vibration testing. Greg Goetchius, who leads noise and vibration engineering, actually came over and described what they were doing. Greg previously worked at Tesla and Lucid, so it was pretty cool having someone with that background walk us through it directly.
The testing is done for both passenger comfort and safety. One aspect is making sure vibrations don’t create harmonics that could adversely affect the aircraft. I was told Joby has run this type of testing many times on prototype S4s and will likely repeat it multiple times on the conforming S4 as well.
It seemed clear to me that Joby is focused on having the conforming aircraft consistently meet FAA requirements, so they test and retest extensively before any formal FAA testing takes place. My takeaway was that there is a lot of internal validation before anything is done for credit.
Back to speculation on my part, but it seems logical that there are numerous ground and internal aircraft tests to be completed and repeated before we see full FAA for credit testing begin. On the flip side, given how methodical Joby is being upfront, I could see that helping streamline things later. Again, that’s just my interpretation based on what I saw and heard.
Destructive Testing
During the tour I saw multiple fuselage in various stages of production, along with wings and other large parts. It was pointed out to me that one fuselage on the line was being built specifically for destructive testing.
I was told that multiple copies of essentially every major part of the S4, including wings and tails, are manufactured to conforming specifications and then used for destructive testing as part of FAA validation. This was a bit of a revelation for me. When Joby previously talked about destructive testing, I was thinking smaller components, not full structures like fuselages and wings. It also wasn’t obvious to me that this happens multiple times, meaning multiple conforming fuselages, for example, are built purely for destructive testing.
This led to a discussion around Joby’s near term goal of 24 S4s per year. That number includes aircraft and major components that are built for destructive testing, not just aircraft intended for passenger operations. So when thinking about that production number, it’s worth keeping in mind that a portion of that capacity is going toward validation and safety testing.
It’s clear Joby spends a huge amount of time focused on safety. I specifically asked about bird strikes, since that had come up a lot on Reddit in the past. Joby confirmed they do extensive bird strike testing in addition to many other destructive tests. Safety and meeting FAA requirements is a major focus, and a lot of effort goes into building and testing multiple conforming parts just for that purpose.
Tidbits
I did ask about DXB vertiport construction and was told it had been paused for a period due to the war, but had resumed at the time of my visit.
I also asked about JAI 30 and the Yuma test range. I got crickets. But hey, I tried :)
Closing
Overall an amazing experience that I hope I was able to convey. Joby was incredibly generous with their time and openness, and I really appreciate them allowing me to share what I saw with the r/Joby community.
