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Zoom Climb?


ekg
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How do you zoom climb? I've tried on the Su-27 and I've only gotten to about 13,000 m. Some people have gotten to at least 25,000 but I find the plane stalls easily past 10,000 m.

 

Does anyone have a video or a track of how to do it? The way I did it was air speed was around 800-900 kph at around 8000m and then I pulled up to around 60 degrees above horizon. At 13,000 I would stall. I use full aft the entire time.

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26,000ft at 495kts 60* climb and you stall at 33,000ft so 7,000ft climb?

 

am I reading this correctly? If I am.. Then the only thing I can come up with is you exceeded AOA in your climb essentially making your self a giant sail instead of transferring your inertia upwards. the only thing at that moment pushing you up would be your engine thrust and none of the stored kinetic energy you had before. SO what I'm trying to say in a more laymen terms you pulled too hard too fast on the stick causing the jet to go nose high and essentially stalling the wings [ sortof like the cobra maneuver]. With that your forward momentum continues forward and the only vertical climb you're getting is from the engines and none of it from the inertia you had before which is still transferring forwards down its orriginal horizontal plane but with the wings and fuselage acting as a huge sail slowing you down in the horizontal plane


Edited by pr1malr8ge

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If your desired effect on the target is making the pilot defecate his pants laughing then you can definitely achieve it with a launch like that.
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I do pull up fairly quickly when I have a decent amount of forward momentum. I read the Su-27 has a service ceiling of 19,000m which so I'm 6,000 meters below this. What is the general technique for a zoom climb? I thought it was all about converting forward momentum to upward momentum. How to do it with out stalling?

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If you want to reach extreme altitudes, you need extreme speed (and sometimes initial altitudes). Climbing from curise height at near cruise speed isn't anything special. Try doing a zoom climb at Mach 1.5+ at 45000 ft or higher.

 

I also recommend moderate g in the pull up (4-5 g). Too little g, and you experience high drag over a long period of time. Too much g and you bleed all your speed.

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I do pull up fairly quickly when I have a decent amount of forward momentum. I read the Su-27 has a service ceiling of 19,000m which so I'm 6,000 meters below this. What is the general technique for a zoom climb? I thought it was all about converting forward momentum to upward momentum. How to do it with out stalling?

 

Well yes it is about converting forward momentum to upward momentum. How ever the plane is capable of pulling the nose though its CAOA before the wings have the ability to transfer stored inertia from one plane of travel to the next. As Exorcet says you need to pull around 4-5Gs and smoothly not abruptly.

 

By the way service ceiling is not a product of limitation of zoom climb. It's generally a rating of sustained climb performance degrades[best rate of climb] or when some other factor limits the plane from safely being able to climb further. The plane can still climb and when it can no longer climb that is the absolute ceiling these do not include zoom climbing as essentialy they result in departure of controlled flight.

 

If you want to reach extreme altitudes, you need extreme speed (and sometimes initial altitudes). Climbing from curise height at near cruise speed isn't anything special. Try doing a zoom climb at Mach 1.5+ at 45000 ft or higher.

 

I also recommend moderate g in the pull up (4-5 g). Too little g, and you experience high drag over a long period of time. Too much g and you bleed all your speed.


Edited by pr1malr8ge

For the WIN

[sIGPIC][/sIGPIC]

If your desired effect on the target is making the pilot defecate his pants laughing then you can definitely achieve it with a launch like that.
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If you want to reach extreme altitudes, you need extreme speed (and sometimes initial altitudes). Climbing from curise height at near cruise speed isn't anything special. Try doing a zoom climb at Mach 1.5+ at 45000 ft or higher.

 

I also recommend moderate g in the pull up (4-5 g). Too little g, and you experience high drag over a long period of time. Too much g and you bleed all your speed.

 

At 45000ft (13000) meters I find it very difficult to maintain my speed above 500kph. Any tips on how to reach Mach 1 let alone Mach 1.5

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First thing would be to accelerate before getting to altitude, or diving from altitude and then coming back up.

 

There is also a trick to increasing acceleration by reducing angle of attack. This will mean that you can't hold 1g while doing this (you will slowly pitch down) but you reduce drag and accelerate faster than you would while flying level or flying in a constant shallow dive.

 

Here is a clip from the Streak Eagle record flights to give you some ideas on a flight profile:

 

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At 45000ft (13000) meters I find it very difficult to maintain my speed above 500kph. Any tips on how to reach Mach 1 let alone Mach 1.5

 

You're looking at IAS. Just because you're at 500kph does not mean you GS and or mach speed isn't higher.

 

500kph is ~269 knots per hour and in the Eagle at 45,000ft at that speed I think should be around 1.2-1.4m

 

Once I get above 28,000ft I fly by Mach and not by IAS.

For the WIN

[sIGPIC][/sIGPIC]

If your desired effect on the target is making the pilot defecate his pants laughing then you can definitely achieve it with a launch like that.
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I'll re-post what I posted in the trim thread:

 

First you need a clean bird, no weapons loaded but quite a lot of fuel. I usually take 100% fuel. Climb gently under full military power until you reach 11,000m. At that point engage afterburner until true air speed reaches ~1100 Km/h. At that point climb gently to ~13,000m and then level out. Wait until speed reaches 2.5M before pulling in to a 3-4 G climb with a ~50-55 degree nose-up pitch. It's usually best to wait until you're down to ~3,000 Kg of fuel before pulling up so the aircraft is nice and light but you'll still have enough fuel to land.

 

Once you're in a zoom climb keep the nose at ~50 degrees up no matter what your IAS is because the actual true air speed will still likely be above 800 Km/h. Keep climbing until you run out of lift at which point you'll nose over no matter what you do.

 

The point of not going above ~50 degrees pitch up is that when you do eventually stall and nose-over the thing will deep stall in a stable manner rather than departing.

 

Edit to add a test track. When you see the in-cockpit altitude remember that the actual altitude is not calibrated to air pressure and will therefore under-read. Tacview reports maximum speed as 2.6M and maximum true altitude as 35,104m. Not bad at all.


Edited by DarkFire

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You're looking at IAS. Just because you're at 500kph does not mean you GS and or mach speed isn't higher.

 

500kph is ~269 knots per hour and in the Eagle at 45,000ft at that speed I think should be around 1.2-1.4m

 

Once I get above 28,000ft I fly by Mach and not by IAS.

 

Most jets should be using mach numbers above FL180.

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To set up for a good zoom climb, I do the following:

 

1: Climb to 7km on MIL power, adjusting pitch to maintain mach 0.9 (afterburner is too inefficient below this altitude in DCS)

2: level out and accelerate via afterburner to mach 1.3-1.5

3: gently lift the nose to 5 degrees and climb to 12km. Your rate of climb with this speed/pitch should be 40-50 m/s, and you should still be accelerating slightly, or at least maintaining TAS.

4: level out and accelerate until fuel state is ~800 kg, or mach 2.5 is achieved, whichever occurs first

5: pull back at a steady 3G (watch you AoA/G-force indicator) until you are nose up @ 55 degrees.

 

This will put you into a zoom climb that will get you to a minimum of 25km, depending on how steady your hand is on the stick.

 

One mistake many people make is to try and jerk the nose up. While this works fine at sea level, at high altitude the air is too thin to maneuver sharply, and all you end up doing is aerobraking. it is important to keep your AoA well below stall threshold at all times during a zoom climb.

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I managed to get to 91,700ft in the F-15 just now. I kind of followed the video above.

I probably could have made it higher if I had pulled up faster in the end. I think I did it too slow. Ignore the bad landing at the end, haven't played the F-15 in a long time, lol

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