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About rahill

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    Reid Hillview Airport, San Jose, CA (KRHV)
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  1. But that reference states "This approach only holds for a blunt impactor (no aerodynamical shape) and a target material with no fibres (no cohesion), at least not at the impactor's speed. This is usually true if the impactor's speed is much higher than the speed of sound within the target material. At such high velocities, most materials start to behave like a fluid." (note: speed of sound in aluminum is ~6000m/s) It then goes on to discuss very high density projectiles, shaped charges, and the like. That's not the case here. Perhaps you meant to include the reference about impacts (from the same site) https://www.revolvy.com/page/Impact-(mechanics). "When vehicles collide, the damage is proportionate to the relative velocity of the vehicles, the damage increasing as the square of the velocity since it is the impact kinetic energy (1/2 mv2) which is the variable of importance."
  2. This was covered in the video (the longer one, not the 0:43 second clip). An equivalent mass bird deformed more and did less damage. The density of the drone, particularly the heavy battery, is something to consider.
  3. Energy goes up as the square of the speed. They address this in the video and mention closing speeds, assuming some velocity of the drone. The DJI they used is capable of 30+ mph so take that into account. 238 mph is maybe a bit fast, but (also addressed in the video) these things have the capability of doing more damage than an equivalent-mass bird.
  4. rahill

    Mooney in the water in Palo Alto

    Can you double check this, or provide a reference? Best glide in an M20J is about 90 kts (load dependent). The low point in power curve (left of which is "backside") is the point of minimum drag, not the point of best glide. Best glide (L/Dmax) is to the right of that. I know we're mixing up topics now, but if you cross the threshold of Palo Alto at 80-85 KIAS, you're probably not going to land on that attempt. Rich
  5. rahill

    Palo Alto Crash 9/4/2018

    Yes, I did something similar (a practice/estimate W&B, not a stall!) - I was a bit surprised to find that it was within range. Rich
  6. rahill

    Mooney in the water in Palo Alto

    Wind was 6 kts at 040 so 90 degrees to 13 (which was the runway in use at the time, not 31). He was clearly unfamiliar with the airport - requested assistance finding the KGO towers when asked to fly there, then later requested help finding the runway. Finally found the runway on ~2 mile final - not a lot of time to set up for a relatively short field. The prop strike comment is speculation, we'll have to wait for the report to find out.
  7. “Two more months” - seriously, that’s what they said. Not really believable at this point though.
  8. Yes, count us in. Rich & Kim Hill
  9. rahill

    Any KPAO pireps?

    We were based in Palo Alto for about 10 years - I don't think I ever saw the airport full. If transient fills, it seems like there should be other places available. There is a rebuild project that will affect (or already is affecting) the tie down areas. Best bet would be to call the airport and ask. Rich
  10. rahill

    Garmin 335 transponder deal

    What are you "not sure" about enhanced traffic awareness? Now, with ADS-B out, you'll get traffic from the GDL 39 all of the time, instead of some of the time - it's a huge enhancement.
  11. We use this occasionally:
  12. The mounts are different, so yes that's pretty much the summary. You likely have this installed: http://www.mypilotstore.com/mypilotstore/sep/7871 And the Aera uses this: https://buy.garmin.com/en-US/US/p/51125
  13. The Garmin Aera 500 series has the same ability, and I would assume the other Aeras do too. You will need to change the wired connection to whatever portable you choose, but that's simple. You're looking for the Garmin Power/Data cable that works for the particular Garmin you want to use. Once you've done that, and set the data format correctly, the 430 will cross-feed flight plan info and, if you have it, weather and traffic data as well. I previously had our 430 cross-feeding a Garmin 196. Now I have the 430W cross-feeding an Aera 510. The 430W is getting ADS-B data from a GTX345 and it also passes all that data (weather + traffic) to the 510. FWIW, you can also set up the Aera to accept flight plan data from the 430 and traffic and weather from a GDL 39 at the same time. Rich
  14. The GTX 345 does send AHRS data (via bluetooth) to the iPad.
  15. I don't think that image is showing TargetTrend, rather that's the standard traffic picture that the 430 and 530 provide with a GTX 345 or any other device that can feed it traffic data. The 430 and 530 display the altitude difference, vertical trend (climbing or descending), and the velocity vector (relative to the ground) of the target. The velocity vector (i.e., ground path) of a target is useful but doesn't really tell you which way the target is headed relative to you, since you're moving as well. TargetTrend (on the GTN units, Pilot, 796, etc.) displays the _relative_ velocity vector, which is a much more meaningful and helpful piece of data. It's a simple calculation but apparently the vector math taking your velocity and the target velocity into account is a bit much for the older units. Rich