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Comment by spitfire | Hacker News Reader

Austin is the author of x-plane, an FAA certified flight sim. It's the only sim that actually calculates lift and drag available to consumers. MS flight sim is just a joke relying on rubber-band type lookup tables. If there's anyone who can do it, it's Austin.

However, relying on the ipads gps and gyros seems like a poor choice. I wouldn't trust the ipad to have the necessary precision to pull off a landing. If you could interface the ipad with onboard GPS/gyro's then I'm all for it. The ipad has a plenty fast cpu for this sort of thing. But then so does a 286. or a PCjr for that matter.

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I think the iPad's GPS is just to find a nearby waypoint as a starting point for the automatic approach and landing. Once you have decided upon a route, it's a simple matter of tuning the aircraft's nav radio to the VOR or ILS. From there, you have the full precision that you would normally have on an instrument approach/landing. The innovation is that the passenger doesn't have to know what an instrument approach is.

(I wonder if the code on the iPad gets the audio stream from the radio so that it knows it's tuned to the right channel.)

As an aside, I've read on the X-Plane forums that X-Plane doesn't actually do a full simulation as you say it does. If you try to spin the default C172, for example, you can't do it, because the aerodynamics near the boundary cases are not calculated correctly. (Either that, or the spin recovery for a C172 consists of letting go of the controls and waiting, which is not what the manual says. But I have not tried it.)

A 172 will recover from an upright (non-inverted, non-flat) spin by simply centering the flight controls and waiting.

Anti-spin inputs (power idle, center controls, opposite rudder, elevator down) make the recovery much quicker, but I was taught (and shown) that if you don't know which rudder to use to stop the spin, to just center the controls and the 172 will stop spinning on its own.

Disclaimer: I'm just a pilot and not a CFI; if you go spin one into a smoking crater following procedures other than the book, don't blame me, etc.

Interesting. Hopefully I will get to try this in the not too distant future :)

X-Plane uses blade element theory - essentially it breaks various flying surfaces of an aircraft apart and calculates the forces on each one of those parts to simulate how it could react. Not perfect, but better than the MSFS approach.

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