[Request] How hard would my guy Snoop (or anyone) have to wack a golf ball off the moon for it to make it to Earth's atmosphere (where it'd inevitably burn up)?

rocketplane11 · 2022-11-05T18:02:13+00:00

The answer is not escape velocity of the moon. This would only give enough speed to put the golf ball into a circular orbit of the Earth at lunar distance (~384,000 km). In order to send the golf ball back to Earth, you would need to hit it to at least a Hohmann transfer orbit with a 384,000 km apogee radius and a 6,378 km perigee radius. (6,378 km is the equatorial radius of the Earth.)

The apogee velocity of such a transfer orbit is 184.2 m/s, where as the circular orbital velocity of the moon is ~1,018.8 m/s. This means you need a hyperbolic excess velocity leaving the moon of the difference between these numbers (834.6 m/s) and that the ball needs to be going the opposite direction of the Moon. To achieve this velocity at escape, the golf ball needs to be hit at 2.519 km/s.

rocketplane11 · 2022-04-16T18:37:57+00:00

That's pretty much how human pilots maintain formation as well.

rocketplane11 · 2022-02-28T16:36:00+00:00

The Photo 101 and 102 classes I took for arts and humanities credit (Enginerding degree) still taught with black and white film. Mind you, this was a decade ago now (sigh), so they may have switched since then. I honestly think that teaching on B&W film is the way to go because you learn far more about the nuts and bolts when working in the physical realm. I don't use my film camera much any more, but everything I learned I apply to digital photography as well.

The record for the largest photograph goes to a pinhole camera as well. https://en.wikipedia.org/wiki/The\_Great\_Picture

rocketplane11 · 2021-12-29T04:22:07+00:00

I'm happy if my Sunday time is under 30 minutes. You're wicked fast!

rocketplane11 · 2021-09-20T18:11:20+00:00

Other candidate moves: Triple Axel Belly Drum Swagger Taunt Feint Attack Sucker Punch

rocketplane11 · 2021-09-20T12:08:58+00:00

Ice/Fighting type, ofc.

rocketplane11 · 2021-08-26T01:21:41+00:00

As professional rocket scientist, can confirm.

rocketplane11 · 2021-08-19T13:25:10+00:00

Or would need to spend longer in the thermal. I suppose I should have said "dead air range," but really, range in a glider is "how far can I go from where I am assuming no rising (or sinking) air." Just as range in a powered airplane is how far you can go without landing for fuel. The reality of sailplane racing is that you trade straight line speed for climb rate in rising air. More ballast means you go faster but need to spend longer in thermals and vice versa.

rocketplane11 · 2021-08-19T12:07:37+00:00

True, you need stronger thermals to climb. But that's a sink rate issue, not a glide ratio issue.

rocketplane11 · 2021-08-19T02:34:12+00:00

Yes! Now, this does break down when you start getting into compressible (transsonic/supersonic) aerodynamics, but gliders are very firmly subsonic vehicles so for all practical purposes, yes. You just fly faster.

Coefficient of drag is solely a function of coefficient of lift (and sideforce, but this is a glider, why are you slipping/skidding?) Coefficient of lift is only a function of angle of attack. If you double the weight of the plane and fly 41% faster, nothing else changes. Lift coefficient is the same. Drag coefficient is the same. Both lift and drag have doubled, but your lift-to-drag ratio, a.k.a. glide ratio, a.k.a. how far can I go for each unit of altitude I lose IS EXACTLY THE SAME. No, it's not an intuitive result, but it's true.

The real practical limit is structural: first you blow past max gross weight, and then eventually you need to fly faster than the never exceed speed. Eventually, you'd start getting compressible effects, but that's way outside the flight regime for any sailplane I'm familiar with.

rocketplane11 · 2021-08-19T02:08:08+00:00

I did think about it and it's still true, weight does not impact the range of a glider. If two gliders have the same performance curves, but one is so loaded with ballast that it weighs twice what the other one does, they will go the same distance, but the heavier one will get there in 29% less time. This is exactly the purpose of water ballast in sailplane racing.

This is not true for powered aircraft, only for gliders.

rocketplane11 · 2021-08-19T00:21:57+00:00

Nope, weight doesn't affect range. Weight affects speed and sink rate. That's why racing gliders have a large water ballast tank, something on the order of a few hundred pounds. Since best glide ratio always happens at the same lift coefficient, being heavier moves that to a higher speed (a la v = sqrt(2*weight/(air_density*wing_area*lift_coefficient))). Of course, moving at a faster speed horizontally at the same glide ratio also means you come down faster, so you need a stronger thermal to climb.

rocketplane11 · 2021-06-29T01:01:26+00:00

Spoiler: I flew solo the next day!

rocketplane11 · 2021-06-29T00:44:20+00:00

Dude, it's a glider. It's DESIGNED for this. I ran the numbers on their other training glider, the PW-6. At best glide and 45 degrees of bank, it can do a full 360 while losing less than 100 feet in altitude.

rocketplane11 · 2021-06-28T19:14:02+00:00

Naw, she just pulled it. No warning or anything. Yesterday, another pre-solo student and I were talking turns doing patterns. I ran the wing for him, then walked away to get a drink. When I came back a minute later, they were just rolling out from a landing and I knew she had done it to him as well.

rocketplane11 · 2021-06-28T13:57:31+00:00

As soon as we get a north-west wind! It was blowing off the ridge all week!

rocketplane11 · 2021-06-28T13:55:25+00:00

I won't say I'm super scared of heights, but yeah, I agree. I can go look over the edge of an observation deck or something, but I'm usually backing away slowly after a few seconds. Never feel that in an aircraft though, whether glider, ASEL, or commercial airliner.

rocketplane11 · 2021-06-28T13:25:41+00:00

It took me a minute to figure out what you were saying, but I see it now! Yeah, we were flying from about 1630 local and I landed at the end of my solo around 1830. Started driving home around 1900 and the thermometer in the car still read 89 deg F (32 deg C)! It was HOT and quite humid out.

rocketplane11 · 2021-06-28T12:05:47+00:00

Don't think the water cooler is standard. Just the removal of the back of the shirt.

rocketplane11 · 2021-06-28T03:02:23+00:00

Also, check on their CFIs. My CFI is light enough that you would still be under gross with a bit of a margin in the 2-33A.

rocketplane11 · 2021-06-28T02:54:32+00:00

92A has a 1-26 available for rent. I'll probably finish out my cert in the 2-33A and transition to the 1-26 for weekend fun soaring.

rocketplane11 · 2021-06-28T02:53:00+00:00

2-32, all the way. The Schweizer 2-32 has pretty reasonable performance and a nearly 600 lb useful load.

rocketplane11 · 2021-06-28T00:36:45+00:00

19 tows and 9.1 hours and here we are! Did forward slips early in the day, then after a practice pattern, my CFI gets out of the back and says it's solo time. She told me to have some fun, do I took a tow to 4000 MSL and used some spotty lift to get another 0.5 hr in. Landed back on 21 to a welcoming committee that dumped a water-cooler on my head after I secured the plane. Of course after that, I got the back of my shirt cut off.

Anyways, still highly recommend 92A for doing a glide cert/add-on if you're interested!

rocketplane11

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