Parobolic flight for zero gravity

SixPapaCharlie

SixPapaCharlie

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I am trying to find the steps to do this with the most effectiveness.

I have seen lots of videos of this being done. I am trying to find the step by step instructions.

Currently I am pointing the nose up until whenever and then forcing it down whenever not sure how throttle needs to play into it.

I have attained brief moments of weightlessness but when I say brief I mean 1/2 second.


This is of course my ultimate goal. Man I hate my dog :D
 
I'm thinking it's about time you go back to Tim's hangar and buy one of those RV-8's.
 
Keep us posted if you find the technique.

I'm surprised no one has raised 'careless and reckless' regarding that video; or even animal cruelty....
 
SixPapaCharlie said:
Currently I am pointing the nose up until whenever and then forcing it down whenever not sure how throttle needs to play into it.
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That works. There's no such thing as step-by-step for flying at zero G. Pitch up to some degree then push forward a little. Use common sense. As with any maneuver, don't exceed G limits or airspeed limits. Keep the engine under redline with throttle if it makes you feel better.

I assume you're doing this for fun? If so, remove or secure any loose items in the cabin. You probably figured this out from that video. Be prepared to clean some oil off the belly after flying at zero G. Be prepared to see your oil pressure drop off around zero G. This doesn't hurt anything for brief periods.

I think you should just go ahead and get an aerobatic airplane. :)
 
Pull the throttle to idle whenever the nose is below the horizon. That will give you more time before your speed gets excessive. Do not exceed Vne and think 27 times about exceeding Vno.

Note that some airplanes are not approved for ANY negative G's. E.g., Piper PA-28.

Even the Vomit Comet only gets some 20 seconds or so of zero-G, and that's a jet with cruising speed three times its stall speed. Don't expect more than a few seconds in a low power, low speed spam can.
 
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whifferdill said:
That works. There's no such thing as step-by-step for flying at zero G. Pitch up to some degree then push forward a little. Use common sense. As with any maneuver, don't exceed G limits or airspeed limits. Keep the engine under redline with throttle if it makes you feel better.

I assume you're doing this for fun? If so, remove or secure any loose items in the cabin. You probably figured this out from that video. Be prepared to clean some oil off the belly after flying at zero G. Be prepared to see your oil pressure drop off around zero G. This doesn't hurt anything for brief periods.

I think you should just go ahead and get an aerobatic airplane. :)
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Yes, just for fun. My dad did this with us as kids and he would make pennies float. I tried it with my wife in the plane and she thought it was the coolest sensation but I am unable to to actually make anything "float"

The plane is rated +4.4 and -1.8
I don't think I could come anywhere near either of those.

I think I may be nosing over too slow. I have been climbing full power and pushing the nose over as I approach stall speed.

From the videos it looks like they are pitching up and pitching down about 2-3X quicker than I am.
 
MAKG1 said:
Pull the throttle to idle whenever the nose is below the horizon. That will give you more time before your speed gets excessive. Do not exceed Vne and think 27 times about exceeding Vno.

Note that some airplanes are not approved for ANY negative G's. E.g., Piper PA-28.
Click to expand...

I couldn't hit Vne if the wings fell off. Same is true with VNO.
Our airspeed indicator markings are quite optimistic.


 
MAKG1 said:
Pull the throttle to idle whenever the nose is below the horizon. That will give you more time before your speed gets excessive. Do not exceed Vne and think 27 times about exceeding Vno.

Note that some airplanes are not approved for ANY negative G's. E.g., Piper PA-28.
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This. And don't be afraid if the engine quits... it'll come back on when you pull up.

On a 172, I enter at around 100kts, pull up, full throttle, when I get to exactly 30* nose up ;) I begin the pushover, and cut the throttle as the nose comes through the horizon. Work up to bigger and bigger ones as you get more comfortable. I generally can hold around 3 seconds at 0g. Make sure the cabin is secure.
 
dmspilot said:
What? :confused:
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Read section 2 of your POH. Carefully.

It will have load factor limitations. For a PA-28 in normal category, it is 0G-3.8G. In utility category, it's 0G-4.4G. For comparison, a 172 limitation is -1.5G-3.8G in normal category.
 
SixPapaCharlie said:
I am trying to find the steps to do this with the most effectiveness.

I have seen lots of videos of this being done. I am trying to find the step by step instructions.

Currently I am pointing the nose up until whenever and then forcing it down whenever not sure how throttle needs to play into it.

I have attained brief moments of weightlessness but when I say brief I mean 1/2 second.

This is of course my ultimate goal. Man I hate my dog :D
Click to expand...

I remember seeing the video years ago, and not finding it funny.
 
MAKG1 said:
Read section 2 of your POH. Carefully.

It will have load factor limitations. For a PA-28 in normal category, it is 0G-3.8G. In utility category, it's 0G-4.4G. For comparison, a 172 limitation is -1.5G-3.8G in normal category.
Click to expand...

Is the PA-28 placarded against downdrafts? :)
 
Also check to see if there are any engine limitations. I know that the Rotax 912 is limited to 5 seconds of nonpostive Gs (or some wording like that).
 
ebykowsky said:
This. And don't be afraid if the engine quits... it'll come back on when you pull up.

On a 172, I enter at around 100kts, pull up, full throttle, when I get to exactly 30* nose up ;) I begin the pushover, and cut the throttle as the nose comes through the horizon. Work up to bigger and bigger ones as you get more comfortable. I generally can hold around 3 seconds at 0g. Make sure the cabin is secure.
Click to expand...

Oh heck, that's for amateurs. I enter and 120 kts from a shallow dive, pitch to 45 degrees nose up, push over, cut the throttle, hold it for five seconds, continue inverted and transition in to a barrel roll, enter a dive at 45 degrees, pull out at 3.8 g's, add full thottle as I go vertical, then recover in an Immelman.

And that's just a warm up.
 
jpower said:
Also check to see if there are any engine limitations. I know that the Rotax 912 is limited to 5 seconds of nonpostive Gs (or some wording like that).
Click to expand...

No such limitations with Lycomings.
 
Sac Arrow said:
Oh heck, that's for amateurs. I enter and 120 kts from a shallow dive, pitch to 45 degrees nose up, push over, cut the throttle, hold it for five seconds, continue inverted and transition in to a barrel roll, enter a dive at 45 degrees, pull out at 3.8 g's, add full thottle as I go vertical, then recover in an Immelman.

And that's just a warm up.
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Ok, I will try it that way this evening.

Edit: and you do it with foggles on correct?
 
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jpower said:
Also check to see if there are any engine limitations. I know that the Rotax 912 is limited to 5 seconds of nonpostive Gs (or some wording like that).
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FYI, Rotax 912 limitations state no longer than 5 seconds at -0.5g maximum negative, in order to maintain proper engine lubrication with the oil sump system.
 
SixPapaCharlie said:
I think I may be nosing over too slow. I have been climbing full power and pushing the nose over as I approach stall speed.
Click to expand...

That right there is your problem. You're trying to fly a parabola. You want to start FAST, not slow!

Start with full power and a lot of altitude. Push the nose over to gain MORE speed, pull up aggressively but well within the limitations of the airplane, and then push. If you hit the seat belt you're pushing too hard. If you're still on the seat, you're not pushing enough.

Speed-wise, you want to start fast, pull moderately hard, and ideally start the push at such a time that you'll be very slow at the top of the arc. You don't need to worry about being below stall speed because at 0 G you cannot stall (remember that at 0 airspeed, you don't have any control effectiveness either).

Whatever angle you start the push from, pretend you're a baseball getting thrown at that angle, and visualize the path the ball would take. Fly that path, adjust as described above.

On the downhill, DO NOT wait until even the yellow arc before you start the pull-out. You need to be able to level off prior to Vne (or Vno if it's bumpy at all), and that means you need to start the pull well before to ensure you don't accelerate through it.

It'll take practice to get this right. Realize that you're going to be flying a lot closer to the edge of the envelope than you're used to, and plan in advance how you're going to not exceed the envelope. Might not hurt to get some aerobatic instruction in an aerobatic plane, then you can make that G meter go all over the place. :)
 
bullwinkle said:
FYI, Rotax 912 limitations state no longer than 5 seconds at -0.5g maximum negative, in order to maintain proper engine lubrication with the oil sump system.
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I was close! It's been a while since I've flown behind a Rotax. Thanks for the correction.
 
bullwinkle said:
The dog looks pretty sanguine about the whole thing...it might be a frequent passenger on these flights. :lol:
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Wow, I just learned a new word. I had to Google it. All this time I thought it was a flat pasta.
 
I flew as a passenger on NASA's KC-135 "Vomit Comet" about ten years ago. The NASA pilot flew fabulously good parabolas.

I remember hearing the engines spool up and down. I don't recall exactly when the throttle was changed, but it might have been idle during zero g on top, transitioning to full throttle while pulling up for the non-zero-g portion at the bottom.
 
MAKG1 said:
Read section 2 of your POH. Carefully.

It will have load factor limitations. For a PA-28 in normal category, it is 0G-3.8G. In utility category, it's 0G-4.4G. For comparison, a 172 limitation is -1.5G-3.8G in normal category.
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Pretty sure that for an airplane to be certified in the normal category, the following applies:

Normal Category is a certification category. This category has a maximum G loading of +3.8 G's (positive G's) -1.52 G's (negative G's). Usually spins and other maneuvers that exceed the normal flight envelope are prohibited.
 
All that means is that the structure won't fail. There could be other reasons for the prohibition on inverted loads, for instance fuel or oil starvation, hydraulic cylinder failure due to abnormal oil loading, or unrecoverable dynamics.

The limitation is in section 2, and 14 CFR 91.9(a) applies.
 
There isn't much I can say about flying 0gs that hasn't been already said. I would however recommend you go up with an aerobatic instructor and have him show you how do to things properly. There is only so much we on the forum can recommend without actually seeing you fly.
 
Is it acceptable for a private pilot to do that? Dont think I would try them with a new passenger. :eek:

 
MAKG1 said:
There could be other reasons for the prohibition on inverted loads, for instance fuel or oil starvation, hydraulic cylinder failure due to abnormal oil loading, or unrecoverable dynamics.
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All total BS. All airplanes are equally susceptible to fuel and oil starvation unless equipped with aerobatic inverted fuel/oil. Nothing special about a Cherokee. Hydraulic cylinder failure, "abnormal oil loading", and "unrecoverable dynamics"? This is a pull straight out of your arse.
 
JasonM said:
Is it acceptable for a private pilot to do that? Dont think I would try them with a new passenger. :eek:
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No. This sort of thing is reserved for professional pilots like the one in the video (notice the epaulets?).
 
RoscoeT said:
All total BS. All airplanes are equally susceptible to fuel and oil starvation unless equipped with aerobatic inverted fuel/oil. Nothing special about a Cherokee. Hydraulic cylinder failure, "abnormal oil loading", and "unrecoverable dynamics"? This is a pull straight out of your arse.
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Dude, I did NOT write the Cherokee POH. Look it up. The limitation is there.

I can speculate about reasons, but if you can't distinguish that, GO ARGUE WITH THE ACTUAL AUTHOR.

Oh, and another hint is that I didn't write 14 CFR 91.9(a) either.
 
MAKG1 said:
Dude, I did NOT write the Cherokee POH. Look it up. The limitation is there.

I can speculate about reasons, but if you can't distinguish that, GO ARGUE WITH THE ACTUAL AUTHOR.

Oh, and another hint is that I didn't write 14 CFR 91.9(a) either.
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You're deflecting the response to your own ridiculous comments. I guess 14 CFR.9(a) and the Cherokee POH also talk about "hydraulic cylinder failure", "abnormal oil loading", and "unrecoverable dynamics". ;)

Folks, don't ever subject a Cherokee to zero G, the hydraulic system will explode and the airplane will spin uncontrollably to the ground. ;)
 
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One thing to watch out for is the last time the plane was vacuumed out.

I was taking some friends up awhile back, an they wanted to do some 'fun stuff'. Started with a a few steep turns and gentle push overs, and they wanted more. So I did a 0G push over, and the cabin went IFR as years of dust and dirt floated up.
 
RoscoeT said:
You're deflecting the response to your own ridiculous comments. I guess 14 CFR.9(a) and the Cherokee POH also talk about "hydraulic cylinder failure", "abnormal oil loading", and "unrecoverable dynamics". ;)

Folks, don't ever subject a Cherokee to zero G, the hydraulic system will explode and the airplane will spin uncontrollably to the ground. ;)
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You clearly don't understand what a speculation is, or what qualifiers like "perhaps" mean.

Does it matter why it's prohibited? It's prohibited.

If you don't know why, it's particularly stupid to ignore it. And it's illegal even if you do know why.

My point was that structural failure was not the only reason for a limitation. It isn't.
So, you can either take irrelevant speculation far too literally, or you can make an effort to understand what you read.

There are many ways an airplane can create an emergency aside from the wings coming off.
 
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