On 5/25/2022 at 2:35 PM, hatchna said:

to mimic LEO spacecraft like the space shuttle orbiter

The shuttles mainly flew upside down to point the cargo bay at the Earth. They did that because the heat dissipation radiators were on the inside of the cargo bay doors, and pointing them at the Earth all the time guarantees you'll never be pointing them directly into the sun, which would make them ineffective.

  

4 hours ago, Stearmandriver said:

Where do you get the idea that simply lowering the nose will result in anything near zero g?  That's my entire point about an airliner

Airliners aren't going Mach 9 when they nose over. The faster you go, the more gradually you have to change direction. Picture a roller coaster. When you get over the top of the lift hill, you're changing direction very steeply but don't feel any g-forces. Once you get to the bottom of the hill, if it changed direction in the same way and in the same distance, you'd probably snap your neck.

Humans aren't as good at tolerating negative g's as they are at taking positive g's, so you flip planes upside down when you need to point the nose toward the Earth while traviling at high speeds.

This is not only true for hypersonic aircraft. Fighter pilots will fly close to the ground through hilly terrain, and when they crest a hill and want to head down the back side, they'll flip the plane inverted, pull to the angle they need, then flip it back, to avoid enduring a negative g-load.

 

Edited September 15, 20223 yr by eslader

2 hours ago, eslader said:

Airliners aren't going Mach 9 when they nose over. The faster you go, the more gradually you have to change direction. Picture a roller coaster. When you get over the top of the lift hill, you're changing direction very steeply but don't feel any g-forces. Once you get to the bottom of the hill, if it changed direction in the same way and in the same distance, you'd probably snap your neck.

Your roller coaster example has more to do with rate of pitch change than speed... that's not a meaningful speed difference.  (Yes, if the coaster hit that same top of the hill at full speed it would be significant negative g, but that's mostly because the RATE of pitch change would be so much faster.  If you stretched the track out so the full speed coaster experienced the same degrees/second pitch rate, there wouldn't be that much difference. )

Yes, there is a relationship between velocity, rate of pitch, and g.  But it's just not important in this situation (and remember also that mach and velocity are not the same.  Mach 9 at the edge of space is nowhere near 9 times the velocity of an F-15 doing mach one at 15,000ft, because the speed of sound is so much slower up there.)

I think I mentioned earlier in this thread, but I've been flying and teaching fairly aggressive aerobatics in real airplanes for quite a few years.  I also fly airliners for a living.  I have a bit of a background.

I never said there was no reason for any aircraft ever to roll and pull. I said that there is no reason for an aircraft on THIS PROFILE to do so. It's just for the game.  There's no reason not to simply do, say, a .5g bunt.  That'll draw as big of a circle as it draws; you've got nothing but room.  All systems (and the human) are happy because they're still under positive g, and the airplane will accelerate FASTER because you've unloaded 50% of the induced drag. 

2 hours ago, Stearmandriver said:

There's no reason not to simply do, say, a .5g bunt.

At 0.5g the acceleration is about 5m/s^2. Going from 25kft/min rate of climb (= 125 m/s) to -25kft/min rate of climb (= -125 m/s, resulting in a total speed change of -250 m/s) takes 50 seconds. So the 10 or so seconds to perform the maneuver as demonstrated is not feasible with an uninverted flight.

B.t.w. a spectacular example of inverted flight is shown here. I recommend flying this in the Superhornet in VR:

 

Edited September 15, 20223 yr by mrueedi

1 hour ago, mrueedi said:

At 0.5g the acceleration is about 5m/s^2. Going from 25kft/min rate of climb (= 125 m/s) to -25kft/min rate of climb (= -125 m/s, resulting in a total speed change of -250 m/s) takes 50 seconds. So the 10 or so seconds to perform the maneuver as demonstrated is not feasible with an uninverted flight.

It will take as long as it will take, there's no time limit (or there would not be except game.)  You could also do a more aggressive, near zero g bunt (but still positive).  You're also not considering the fact that an aircraft that can roll inverted in the first place will be stressed (and systems designed) for negative g.  That doesn't mean a roll and pull has to involve negative g; of course it doesn't. But only an aerobatic aircraft is going to be rolled inverted or loaded with any significant positive g, so if we're dealing with an aerobatic aircraft to begin with...

Or we're not. In which case you aren't rolling it inverted anyway. 

This whole thing is getting silly. 

10 hours ago, Stearmandriver said:

I said that there is no reason for an aircraft on THIS PROFILE to do so

Oh well, yes. the roll for this Darkstar thing is to give you something to do to try to hide the fact that flying high-altitude/high speed airplanes in a nearly straight line is actually fairly boring. Especially when you can't even really look outside much. 😉

 

 

 

3 hours ago, eslader said:

Oh well, yes. the roll for this Darkstar thing is to give you something to do to try to hide the fact that flying high-altitude/high speed airplanes in a nearly straight line is actually fairly boring. Especially when you can't even really look outside much. 😉

 

You don't have to roll inverted to get the same results. 

On 5/25/2022 at 3:33 PM, virtuali said:

Maybe because it also requires to push down 20 deg to gain speed, so it's supposed to be flown inverted to not suffer from negative Gs.

That makes sense. The aircraft appears to have a low negative g tolerance, and also, in negative g forces, I'm pretty sure g suits don't work and the pilot needs too stay conscious to fly the precise profile to reach top speed.

 

On 9/14/2022 at 6:10 PM, Stearmandriver said:

Where do you get the idea that simply lowering the nose will result in anything near zero g?  That's my entire point about an airliner - they manage to pitch down many times on every single flight without anyone experiencing anywhere near zero g... more like .95g, right? 

Again, if the goal is acceleration, lowering the nose to unload the wing is actually more efficient than rolling and pulling; an unload (not to zero g, but ANY amount of unload) actually reduces drag. 

This is 100% a game construct; there's no legitimate reason for an aircraft on this profile to roll and pull. 

Even in the movie (which of course contains very little aviation reality of any kind), they do show Mav *pushing* the stick forward for a little extra speed. 

Oh, OK. I have an idea for a new profile now, you pitch up to 20° and maintain instead of the whole pull down maneuver. From past experiences, I know that the aircraft can exceed mach 1 in a 20° climb and so there's no need to dive at all. Far more realistic than the stock profile.

Certainly in the test flight world, if desired parameters can be met in a climb, they will be. A dive is only used when necessary. The initial supersonic flights in the X-1 were all on a climbing profile if I remember correctly (the higher you are, the lower the speed of sound anyway.)

On 9/14/2022 at 7:10 PM, Stearmandriver said:

This is 100% a game construct; there's no legitimate reason for an aircraft on this profile to roll and pull. 

Asobo says otherwise.

41 minutes ago, Tuskin38 said:

Asobo says otherwise.

A video game company... says otherwise. 

I think I'll stick with the laws of aerodynamics. 😉

I like the movie in general (entertaining), but I had to laugh when he also altered the trajectory of the aircraft by 90 degrees to the left in a tight turn, while travelling at Mach 10! 
He would have been fruit salad after just a few degrees!  

10 hours ago, Stearmandriver said:

A video game company... says otherwise. 

I think I'll stick with the laws of aerodynamics. 😉

I think this is why I asked this question originally. Because Skunk Works from Lockheed Martin, the same team that developed the SR 71, had input on creating this Darkstar: https://www.thedrive.com/the-war-zone/skunk-works-helped-create-the-darkstar-jet-for-top-gun-maverick

Now I don't know if it was Skunk Works or Asobo, that decided that the Darkstar had to be inverted, to reach Mach 10.  In the movie, the Darkstar is not inverted, if my memory is correct.

My favorite part of the movie sequence is that he survived an ejection at mach 10, and the worst thing wrong with him was he was thirsty.   😂

I agree with C.W. Lemoine - that time would have been so much better spent exploring Rooster's backstory.