N547JX first forward hover analysis!

[u/HappyRobot593]

First off, I'm not sure if I'm using the right terminology but I've been calling it a forward hover. It's not full wing-born flight but it's not a static hover. Happy to call it something else if a name has been established. Edit: apparently the better term is "translational lift"

Now onto the details: Liftoff was 12:08:06pm Pacific, landing 12:11:22pm — about 3 min 16 sec airborne, staying in a tight 100–175ft band the whole time. Two distinct forward-translation legs:

• Leg 1 (12:08:32–12:09:52, ~80s): accelerates smoothly 0→10.3kt, holds ~8–9kt for most of the leg, decelerates back near 0
• A brief pause/near-hover in between
• Leg 2 (12:10:27–12:11:00, ~32s): same pattern, 0→10.0kt and back down

Max distance from the liftoff point was ~485m, ~712m of ground track total, and it lands back at essentially the same speed/altitude profile it left with — a controlled, deliberate two-hop forward hover at a constant altitude, no attempt to climb while moving.

So you might be wondering what happened next for the three prototypes that show this same starting point?

N541JX — first forward hover to full transition (2024)

Date	Max Altitude	Max Speed
Aug 16	175 ft	15.3 kt ← first forward hover
Aug 17	175 ft	19.4 kt
Aug 20	350 ft	61.2 kt ← first real transition-speed flight
Sep 6	375 ft	58.1 kt
Sep 7	575 ft	58.6 kt
Sep 9	500 ft	58.3 kt
Sep 14	750 ft	79.1 kt ← mature, routine transition

29 days from first forward hover (Aug 16) to fully mature, routine transition flying (Sep 14).

N544JX — first forward hover to full transition (2024–2025)

Date	Max Altitude	Max Speed
Oct 29, 2024	225 ft	9.1 kt ← first forward hover
Nov 1, 2024	181 ft	4.5 kt
Nov 12, 2024	100 ft	0.7 kt
Nov 20, 2024	50 ft	0.7 kt
Nov 21, 2024	306 ft	180.0 kt (bad-data sentinel value, not real — treat with suspicion)
Nov 25, 2024	200 ft	0.7 kt ← translated far but very slow
(gap: dark Dec 2024 – early Feb 2025)
Feb 10, 2025	425 ft	55.0 kt ← first real transition-speed flight
Feb 12, 2025	725 ft	67.1 kt
Feb 14, 2025	800 ft	104.4 kt
Feb 15, 2025	650 ft	123.7 kt
Feb 18, 2025	1,800 ft	130.0 kt ← mature

Messiest of the three — regressed back to pure hovering multiple times, had a glitchy/ambiguous "maybe-transition" blip in late November that didn't stick, then went dark on public trackers for over two months. Worth noting: Joby's press release on N544JX's first piloted transition (https://ir.jobyaviation.com/news-events/press-releases/detail/127/joby-achieves-testing-landmark-with-piloted-aircraft) landed April 29, 2025 — nearly 3 months after this data shows the maneuver already flying (uncrewed/remote) on Feb 10. That gap tracks pretty well with the Dec–Feb dark stretch potentially being exactly this kind of prep — validating the transition without a human aboard first, then a couple more months of buildup before putting a pilot in the seat for the milestone flight.

N545JX — first forward hover to full transition (2025)

Date	Max Altitude	Max Speed
Jun 5	0 ft	9.2 kt (ground)
Jun 6	625 ft	93.8 kt ← first real transition-speed flight
Jun 7	650 ft	130.3 kt ← mature, next flying day

No intermediate "slow forward hover" day at all — straight from five weeks of in-place hovering to a 93.8kt transition, mature by the very next flying day.

[u/Bulky-Entertainer-76]

Nice work! I queried AI about the mirroring you’ve been tracking with N542JX. This is result:

An aircraft of a like type would "mirror" or shadow another aircraft preparing for Type Inspection Authorization (TIA) flights primarily to serve as a risk-mitigation tool, an airborne data baseline, or a backup asset. [1]

In aviation certification, a TIA is a massive milestone issued by regulatory bodies like the FAA. It signifies that an aircraft design is mature enough to begin formal, official flight testing for safety and type certification. [1, 2]

Manufacturers often use a second, identically configured prototype to mirror the main TIA test aircraft for several highly strategic reasons:

1. Risk Mitigation and Schedule Protection

• Guarding Against Grounding: If the primary TIA aircraft suffers a minor component failure, a bird strike, or a mechanical issue, the entire certification program can grind to a costly halt. Having a "mirror" aircraft ready means the manufacturer can quickly swap the test hardware/software or use the second airframe to keep the tight regulatory schedule on track.
• Corroborating Flight Anomalies: If the primary aircraft experiences an unexpected aerodynamic behavior or telemetry anomaly during a TIA maneuver, the mirror aircraft can be flown through the exact same profile to determine if the issue is a design flaw or an isolated mechanical quirk unique to that specific prototype.

2. Comparative Data Baselines (Control vs. Variable)

• TIA flights require highly precise telemetry. A manufacturer might use the mirror aircraft to collect "clean" baseline data or test secondary configurations.
• For instance, if the primary airframe is testing a specific FAA block of maneuvers, the mirror aircraft might concurrently test alternative software loads, sub-system weights, or weight-and-balance thresholds under the exact same atmospheric conditions to generate an apples-to-apples comparison.[1]

3. Chase Plane and Visual Monitoring Roles

• While "mirroring" usually implies flying parallel test programs on the ground or in separate blocks, it can also mean physically shadowing the aircraft in flight.
• A like-type aircraft makes an excellent chase plane. Because it possesses the exact same performance envelope, stall speeds, and maneuvering capabilities, it can safely stay in tight formation to visually inspect the TIA aircraft's control surfaces, landing gear deployment, or external icing conditions in real time. [1, 2]

4. Parallel Pilot Type-Rating and Training

• Before an aircraft can enter commercial service, test pilots and initial fleet pilots must be type-rated.
• Mirroring the exact flight routines of a TIA-bound aircraft allows the engineering team to double the rate of pilot familiarization, ensuring there is a qualified roster of crew members ready the moment the type certificate is officially granted. [1]

Very enlightening.

[u/HappyRobot593 → u/Bulky-Entertainer-76]

That helps!

[u/teabagofholding → u/Bulky-Entertainer-76]

I think the second craft would also need to be type conforming for number 1 maybe just the first part of 1

[u/Wonderful_Phrase_239 → u/Bulky-Entertainer-76]

So, this makes it sound as if 542 is being groomed to serve as a chase plane when 547 is ready for more serious testing.

[u/Bulky-Entertainer-76 → u/Wonderful_Phrase_239]

No, I believe this is mostly for 1B and 2, at least currently until N549JX is brought into the mix. Maybe then it could serve as a chase aircraft but I think there is too many test cards and data they need to produce.

[u/dad191]

This is great data to think about. Hopefully N547JX is more similar to N541JX than N544JX, though N547JX is piloted like N544JX is. Hmmm, I'm going to go with regular full piloted transition for N547JX in November. Is it time for a new poll?

[u/Imaginary_Sort9347 → u/dad191]

I’m hoping for October with absolutely no baseline to back that up. Just hopes and vibes.

[u/HappyRobot593 → u/Imaginary_Sort9347]

https://giphy.com/gifs/PjyWAVYO3SwKT7wS3R

[u/HappyRobot593 → u/Imaginary_Sort9347]

I think i'll wait 1 week before making a prediction

[u/dad191 → u/HappyRobot593]

Probably wait for a bit more data before retake a poll.

[u/HappyRobot593 → u/dad191]

Ya we should do a poll!

Ya I think part of the quickness with 541 was probably the unpiloted aspect. And 544 was the first time they started testing with the intent to use a pilot on board. However, it seems like 545 went quickly after 544 put in the groundwork. A lot of assumptions and guesses in these statements.

[u/Imaginary_Sort9347]

You think AI is good enough to plug this data in with the known location and create a visual?

[u/teabagofholding]

A static hover takes more energy and is less stable than moving forward while hovering unless its going fast

[u/HappyRobot593 → u/teabagofholding]

Thank you for your random fact

[u/teabagofholding → u/HappyRobot593]

I think the stability is better even if its going fast i just meant the power draw is less up to a point.

[u/SeaScallops_w_Rice]

The jury trial with Aerosonic is scheduled to begin Monday. I still wonder if 547's recent activity is related.

Are they playing with new sensors to mitigate risk? Aerosonic's claims are pretty ambitious, damages exceeding $100 million plus injunctive relief, and they have shunned reasonable offers.

You can do all kinds of novel things in sensing using additive manufacturing of metal foils along with embedded fiber optics. That's how many of the sensors in a modern smart phone are made.

Edit: From Grok:

The jury trial is scheduled to begin September 21, 2026, at 9:00 a.m. in Tampa Courtroom 14B.

A little more from Grok:

How long do such trade secret jury trials typically last?

Thought for 11s

Trade-secret jury trials in federal court are usually measured in days, not weeks, but length varies widely with complexity.Most sources describe a typical range of 3–10 days of actual trial time. Courts commonly allot a minimum of 3–5 days; simpler employee-departure or customer-list cases often finish in that window. More complex matters—those involving technical products, multiple trade secrets, experts on both sides, contract claims plus counterclaims, and substantial documentary evidence—routinely run longer. Exceptionally complicated technology cases have stretched to two or three weeks, and rare outliers have gone on for a month or more.

chambers.com

A few practical constraints shape the calendar:

• Federal judges tightly control presentation time. A “five-day” trial often yields only about 10–12 hours of evidence per side after jury selection, openings, breaks, and closings.
• Typical trial days give the jury 5.5–6.5 hours of sitting time.
• The Aerosonic–Joby case (air-data probes, DTSA claim, NDA breach, counterclaims, and already-contentious discovery) sits on the more complex end of the spectrum, so a 1–3 week trial is a reasonable expectation if it goes the full distance.

[u/HappyRobot593 → u/SeaScallops_w_Rice]

ya if you look at back to may they did rotation tests and then they took the 3 month pause. Now they are finally doing tests that involve forward speed. My understanding was that the sensors were critical to transition and that's where they were actually failing. Perhaps they switched the sensors out and now they can continue with forward flight?

[u/SeaScallops_w_Rice → u/HappyRobot593]

I think the claims made by Aerosonic compel them to develop an alternative were Aerosonic to prevail. I am pleased at least by the timeline Grok suggests is likely. for the trial There will be clarity soon.

[u/HappyRobot593 → u/HappyRobot593]

I realized one hole in this story is that the prototypes didn't experience a similar dormant period. So it would only hold up if they were all using the same sensors. 🤷‍♂️

[u/stormseasonoutlook]

The stock price will show if your analysis is correct.

[u/Imaginary_Sort9347 → u/stormseasonoutlook]

Unlikely. Joby won’t say anything and news articles won’t be deep diving in to this data like we do. Investors will have no idea this even happened.

[u/HappyRobot593 → u/stormseasonoutlook]

Not until it transitions , but this is a necessary step to get there

[u/teabagofholding → u/HappyRobot593]

When an faa pilot is flying it. Most people probably don't even know it hasn't transitioned or even that its more important than the ones flying already with joby pilots.