r/HOVRSTONK

Hi all. Long time lurker, first time poster. I've been reading everything on this subreddit for a while and watching every interview by Brandon, but I came across a potentially major issue with the X7 that deserves more attention than it's gotten.

It was first raised in DoubleHexDrive's analysis of the X7. In it, he made a very brief comment that the high disk-loading of the X7's fans compared to a helicopter would cause hurricane force winds underneath the aircraft while hovering. This itself isn't necessarily a problem. However, they then (very briefly) suggested this might make the X7 inoperable in many of the intended use cases like military or medevac, because these winds will kick up so much dust or snow that they'd result in dangerous brownouts and whiteouts during takeoff and landing. I think this comment was lost amidst all the other things in that lengthy post. To my knowledge, nobody has brought it up anywhere on Reddit or in interviews. Nevertheless, it's very concerning if true.

Anyway, a few days after the latest Matan interview I was surprised to see that Brandon was replying to the comments on that video. I thus left a comment in which I asked this question. I didn't expect a reply, given that I was late to the party. But to my great shock, a full TWO WEEKS later, Brandon responded to me. I mention this specifically to highlight Brandon's exceptional commitment to the community supporting his company.

Anyway, I've copied his reply in full below, for the benefit of the community to read and debate. Interested to hear everyone's thoughts.

FOOTNOTE:

A pessimist might think it's sketchy that Brandon is wasting time responding to random YouTube comments when he has an aircraft to build, like a certain Archer CEO-by-day reddit-troll-by-night (allegedly). But the content of Brandon's replies read to me instead like someone who understands that genuinely engaging with people about all the nitty-gritty technical details of the X7 will attract a smaller but more sustainable, long term, dedicated investment community driven by confidence in the underlying technology, rather than temporary hype cycles from Jimmy Fallon interviews and super bowl ads for an aircraft that doesn't even transition yet. But that's just my opinion.

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ORIGINAL QUESTION:

Love this design, I've been following Horizon closely and can't wait to see the design progress! But I worry the high diskloading when compared to a helicopter will cause such strong winds underneath it during hover that it would kick up so much dust or snow to become inoperable in some of its intended use cases in the field, like military and medevac. That dust or snow wouldn't just cause brownouts or whiteouts but would also get sucked back through the lift fans and damage them. Any comments on how this issue is being mitigated would be appreciated.

BRANDON'S RESPONSE:

Sorry for the late reply to a great question. A few fundamental truths:

1. A helicopter accelerates a large mass of air less dramatically than a jet-like system;

2. Downwash and outwash is a complex topic that requires a lot of nuanced knowledge to properly understand, likely outside of a YouTube comment.

You are correct in stating that our X7 vertical propulsion system will produce higher velocity down/outwash than a helicopter. However, there is LESS circulation as it essentially blows the dirt/snow out sideways whereas a helicopter has a gentler down/outwash that is more conducive to re-circulation. The down/outwash piece is very over-dramatized in terms of magnitude of forces. The computer simulations often neglect real world factors that attenuate (or sometimes misrepresent) the forces involved. This is frustrating. I've been next to a Harrier landing...it is truly not that dramatic as some of the PhDs buried in their computers would have you believe.