Spaceflight?

[FDEdev 955]

16 minutes ago, domkle said:

 As the story goes, the US never flew the SR71 over the USSR after the record set by a Mig 25M at 123K feet in 1977. The 25-M was designed to intercept the Valkyrie.

Since turbofans and turbojets usually don't work at these altitudes it is almost certain that the Je-266M was at least partially rocket propelled. Russia never provided any details about this aircraft.

Edited December 1, 2019 by FDEdev

[Noodle 626]

58 minutes ago, FDEdev said:

1. Just watched the video and I didn't find a point where the F-16 did even reach 60000ft.

2. But you do know that the F-15 only coasted to this altitude with both engines shut down and at 35kts with basically no airplane control.

Again, that's very uncommon and since no aircraft except the U-2 and the SR-71 have measurable performance above this altitude, I'd say that the lack of a precise atmosphere simulation above 65000ft is negligible. 

Shrug. Just trying to give you open source examples of the demonstrated performance of older jets. MiG-25, MiG-31, F-22, Su-57, all are capable of impressive feats, but you're not going to get a Raptor HUD tape, so...

My point is that it would be a shame if my F-15A, still trucking along at 1.4 Mach on a parabolic trajectory suddenly ran into an invisible glass ceiling. 

We can talk about aero vs reaction control, but I just dont want the airplane to hit a barrier.

[FDEdev 955]

1 hour ago, Noodle said:

My point is that it would be a shame if my F-15A, still trucking along at 1.4 Mach on a parabolic trajectory suddenly ran into an invisible glass ceiling.

We can talk about aero vs reaction control, but I just dont want the airplane to hit a barrier.

Don't know why this should be the case and AFAIK there's not a single flightsim where this happens.

Edited December 1, 2019 by FDEdev

[RioPilot 99]

I think at the very least, sound should fade when you get high up, with the sky getting darker (it already appears to do that), and the control surfaces should lose effectiveness when you get very high up.

Doing parabolic trajectories into the upper atmosphere, and then tumbling back down until you reach the thicker part of the atmosphere sounds like it should be possible.

Edited December 1, 2019 by RioPilot

[martin-w 3,235]

8 hours ago, Noodle said:

They can't stay there, but they'll get there. There's a story in Code One magazine about just how high an F-16 went once. There's HUD tape of a Venezuelan F-16 attempting an intercept against a U-2. The F-104, F-105, and F-4 could all easily zoom to those altitudes. The F-15A, although stripped down for the purpose, went from brake release to 98,000+ feet in 3 minutes.

It's not as uncommon as one might think.

 

"The F-104, F-105, and F-4 could all easily zoom to those altitudes." I think EASILY might be a bit of an exaggeration. Do you have any time to climb data for these aircraft, to 65000 feet? 

[Murmur 3,941]

I too would be a bit disappointed if atmosphere above 65000 ft would not be correctly modeled, since as has been said there are a lot of aircrafts (past and present, production and experimental) capable of reaching those altitudes.

But I think the devs simply meant that the weather is modeled up to 65000 ft, which is certainly sufficient. So I'm not worried.

[FDEdev 955]

42 minutes ago, martin-w said:

Do you have any time to climb data for these aircraft, to 65000 feet? 

Climb and zoom climb are two completely different things.

The climb table and the maneuvering envelope for e.g. the F-104 extends to almost FL600 but the zoom table extends to 98000ft.

Above FL600 there's no measurable performance, afterburner blow out occurs at 75000ft, the 0.5G 'stall speed' is at 85000ft and at 98000ft the 'stall speed' is given for 0.1G.  

Edited December 1, 2019 by FDEdev

[Paraffin 2,197]

Zoom climbs with air-breathing fighters are interesting, but I think they're less relevant than the need to model the X-15 and upcoming "edge of space" tourist flights. I don't expect an X-15 in the default sim, but there shouldn't be any barriers to modeling it with accurate dynamics for the entire flight envelope.

I agree with an earlier post that the 65,000 ft. "limit" is probably referring only to weather injection. The atmosphere should continue to thin out above that altitude, otherwise it's going to get very silly with a constant atmospheric pressure out to infinity. Or worse, a hard ceiling which I've never seen in any flight sim.

[martin-w 3,235]

2 hours ago, FDEdev said:

Climb and zoom climb are two completely different things.

The climb table and the maneuvering envelope for e.g. the F-104 extends to almost FL600 but the zoom table extends to 98000ft.

Above FL600 there's no measurable performance, afterburner blow out occurs at 75000ft, the 0.5G 'stall speed' is at 85000ft and at 98000ft the 'stall speed' is given for 0.1G.  

 

I still dispute your EASILY zoom to those altitudes. That's my point. How are you defining "easy". Wouldn't think it was easy at all. Doable but not easy. Do you have any evidence in terms of citations, links, for the claim its easy? 

[FDEdev 955]

1 minute ago, martin-w said:

I still dispute your EASILY zoom to those altitudes. That's my point. How are you defining "easy". Wouldn't think it was easy at all. Doable but not easy. Do you have any evidence in terms of citations, links, for the claim its easy? 

? I never wrote that it is easy. In fact I previously stated that non of the mentioned fighters can even climb to 65000ft.

The F-104 is one of the very few examples where a zoom table exists and by doing that that you are well outside the operational evelope. 

[Noodle 626]

You guys like splitting hairs. Not many airplanes have a service ceiling above FL650, but many airplanes are perfectly capable of getting up there--and much higher--for short periods of time.

A cursory internet search would prove this to be true. Most supersonic jets can accelerate to their limiting mach number at high-altitude before initiating a zoom climb to very high altitudes.

The reason I brought it up is not to discuss the difference between service ceiling, combat ceiling, or absolute ceiling. Nor to advance the idea that the practice is safe or smart when performed by those other than test pilots (and even then, it's not really "safe"). I mentioned it because there are many aircraft capable of seeing much higher than 65,000 on the altimeter.

Here are the results of a 0.69 second Google search on the topic:

F-4 and F-15:

https://ntrs.nasa.gov/search.jsp?R=19760053940

F-4:

https://theaviationgeekclub.com/project-top-flight-how-the-mighty-phantom-ii-set-a-new-absolute-altitude-record/

F-104:

https://www.i-f-s.nl/f-104-records/

MiG-21:

https://www.thisdayinaviation.com/tag/mikoyangurevitch-e-66-mig-21/

MiG-25:

https://theaviationgeekclub.com/remembering-absolute-altitude-record-set-fedotov-mig-25-40-years-ago/

Et cetera, et cetera...

Most supersonic airplanes can accelerate to near their limiting Mach at high altitude, then pull up to a nominal climb profile that will take them well higher than their combat ceiling.

Edited December 1, 2019 by Noodle

[Mace 1,927]

17 hours ago, Theboot100 said:

65000 feet is the limit to the atmospheric modelling

.de: The weather comes in real time from a weather service. Is there a storm, a cloud or a hurricane where every pixel is reproduced, or do you have some kind of wind shader?

Neumann: We divided the world into squares with a side length of 64 meters each, up to a height of 65,000 feet. For each of these cubes there are values for humidity, air pressure, which particles float around and other sensor data. This also means that the air is moving in the right wind direction and strength.

I know that.  I was asking how high of an altitude that screenshot was from?  I only had one response so far, and that was "pretty high".  heh.

[Murmur 3,941]

7 hours ago, Paraffin said:

Or worse, a hard ceiling which I've never seen in any flight sim.

30+ years ago, "F/A-18 Interceptor" by Bob Zimmerman for Amiga had an hard ceiling at 40.960 ft. 😁 It also had invisible walls at the edge of scenery.

It was funny to do a vertical climb to 40.960 ft, fire a missile and watch it standing still near the wing.

 

 

[RioPilot 99]

1 hour ago, Mace said:

I know that.  I was asking how high of an altitude that screenshot was from?  I only had one response so far, and that was "pretty high".  heh.

Just a pure guess, but I figured that one particular screenshot was taken around 60,000 feet. Hard to say for certain though. With an extended field of view, looks can be deceiving. But the clouds appear low, and the upper sky appears dark, so it definitely seems higher than the cruising altitude of your average jetliner.

[Paraffin 2,197]

2 hours ago, Murmur said:

30+ years ago, "F/A-18 Interceptor" by Bob Zimmerman for Amiga had an hard ceiling at 40.960 ft. 😁 It also had invisible walls at the edge of scenery.

It was funny to do a vertical climb to 40.960 ft, fire a missile and watch it standing still near the wing.

That's cool!

I never had an Amiga, but I remember the early Flight Simulator (Sublogic?) on PC, where the "mountains" in the distance were just a 2D cut-out and you couldn't fly past them. 

Heck, even the current XP11 has a limitation where you can't fly over the north or south poles (except with user hacks), because the terrain tiles are defined as fixed amounts of Lat/Long coordinates, so they're big squares at the equator, and they turn into tiny wedges near the poles. There are too many tiles to load into memory as you get near the poles, so there's a hard limit there. 

Let's hope the new MSFS has no limits like that, either at the poles or at high altitudes and into the near-orbital range.

Edited December 2, 2019 by Paraffin