zero G

[flyguy]

I was listening to a NPR program this AM that had a bit about the Zero G astronaut training in the specially equipped jet aircraft.

It made me wonder. How many seconds duration of zero G can be effected in a stock (or other) Taylorcraft?

I did a little maneuver of having my brother lay a set of keys in his palm and I floated them in front of his face for just a moment, but I have never tried to extend the Zero G duration.

I'm sure we are talking just a few seconds, but anyone tried to see just how long?

DC

[Mark Julicher]

Re: zero G

If you do a long bunt, you better keep one eye on your oil pressure.

[Robert Lees]

Re: zero G

A nice polite trick to play on a passenger (with an appropriate brief) is to put the logbook (or similar) upon the coaming, and then to do a very gentle bunt and get them to collect it in their hand.

It teaches them about the difference between positive, zero and negative G.

If you talk them through it, they understand quite well!

[Norm G]

Re: zero G

Zero G is a hoot, I've done it several times in a Boeing 707. Let me explane, I worked flight test for Pratt and Whitney and we tested engines on our modified 707 testbed for certification.The zero G maneuver is started at 42 thousand feet and lasted for several seconds. It's amazing what floats during that time, pencils, clip boards, nuts and bolts what ever isn't tied down. hopefully none of the crew is having a coffee at the time.Check it out, google Pratt and Whitney test bed 720B. A 720B is a short 707. the plane is red.
Norm G

[NC36061]

Re: zero G

Knowing that terminal velocity is about 120MPH, you would have to maintain around 10,500 FPM decent to achieve extended zero G... one would have to be a mathemagician to calculate the dive angle and airspeed needed for a 10,500 FPM decent, but I'm betting it would exceed Vne.

[flyguy]

Re: zero G

I don't remember that I picked up very much speed before going over the top the last time I did that move. Could not have been more than 2 or 3 seconds over the top at Zero G.
Just got some work done on the plane the last few days. Will have to go out and repeat that maneuver again. Last time was a long time ago.

Oh, I can attest that my plane does not come apart at Vne, which is 140 indicated (I sure hope). I can tell you for sure that my BC12D will go faster than 120 or 140, even with the power pulled all the way off. The reason I know that is that I have seen 140 indicated with the nose pointed up at about a 45 degree angle recovering from a half-turn spin that had a huge distraction in the middle of the maneuver.

Speaking of oil pressure, I think I may have mentioned before, but I saw local pilot run a 65 HP Chief for about 25 minutes or so without oil pressure. Then the prospective buyer (with his inspector present throughout) went ahead and bought the airplane for a premium price after we got the pressure up by priming the pump. This individual and his brother are renown for marginal behavior around aircraft. They scare me silly sometimes.

DC

[3Dreaming]

Re: zero G

Duane Cole used to do aerobatics with the 90 hp Continental in his Tcraft without an inverted oil system, or so I've been told. That included rolling inverted on take off and climbing out inverted.

[Scott]

Re: zero G

the trouble is that gravity will continue to accelerate an object in the absence of drag. Anything in the cabin will continue to accelerate at 32' per second squared. So once you're nose down, the aircraft may initially accelerate faster than the contents of the cabin but before long drag will reduce the aircraft's acceleration but the contents of the cabin, having no aerodynamic drag, will continue to accelerate ie fall forward to the windshield or firewall etc. It does not matter how fast you descend you'll never descend fast enough to prolong the zero g effect.

The illusion of zero g is created by the change of (pitch) direction hence the longer you can fly the necessary arc, the longer the zero g illusion lasts. So in the Tcraft it's just like any other "aerobatic" maneuver... nose down to gain as much speed as you dare up to vne, then nose up, trying not to bleed energy, then push. Zero g will last as long as you can maintain the arc. I'd be surprised if this was more than a few seconds. Note that zero g will occur while you are still climbing. The more power you have the longer you'll be able to prolong.

[Robert Lees]

Re: zero G

Thread drift:

Some of you may know that I like to visit Utah occasionally: well here's Zero Gravity in the San Raphael Swell.

Sorry for the diversion, and no: it's not my music choice either.

[flyguy]

Re: zero G

Well the stupid %$^&*&^%$#%%^ thread software dumped my longer message so I'm too pissed to typed it over right now. Did about 6 seconds over the top today 120 to 120.
DC

OK, AM add-on, I said: Rob, honored that you choose "my" thread, chuckle.

I went up to check a wing wash-out tweak and decided to do the zero G thing. Sharp pullup and brisk push over starting at 120 IAS. Later suspecting my counting one-a-thousand, two-a-thousand might be too fast, I did a blind check against my watch and I was dead on. So about 6 seconds was correct.

Since I was at altitude I did a 1/2 turn spin and on the way down/back I did a simulated GPS/IFR approach that I hope I never have to actually use.

Beautiful flight closed with trying to improve my always marginal RIGHT cross-wind landing. Finally got a good one. (cross winds are almost always left in this part of the state).