JEFF's fuel tanks Jettisoning

[dock999]

I have been experiencing the difficulty of jettisoning JF-17's external fuel tanks for quite a while.  There seems to be a speed limit for dropping tanks. You can not jettison the external fuel tanks until the speed is below around 450 km/h and I wonder if anyone has had a similar issue? ,  The limitation can cause a great deal of difficulty in performing a defensive maneuver after firing a missile.

[DSplayer]

2 hours ago, dock999 said:

I have been experiencing the difficulty of jettisoning JF-17's external fuel tanks for quite a while.  There seems to be a speed limit for dropping tanks. You can not jettison the external fuel tanks until the speed is below around 450 km/h and I wonder if anyone has had a similar issue? ,  The limitation can cause a great deal of difficulty in performing a defensive maneuver after firing a missile.

Unfortunately, it's a limitation and you'll have to slow down to jettison your tanks. Max speed is roughly Mach 0.9 iirc.

[dock999]

4 hours ago, DSplayer said:

Unfortunately, it's a limitation and you'll have to slow down to jettison your tanks. Max speed is roughly Mach 0.9 iirc.

Right, so this is a  known limitation.

[Mike_Romeo]

13 hours ago, dock999 said:

Right, so this is a  known limitation.

Its a real life safty limitation yes. However, they dont apply to the smaller 800L tanks.

[Napillo]

Yes, the smaller tanks can jettison at a pretty quick clip, and if you're loading on the large tanks, you're taking too much fuel.

[dock999]

On 12/14/2023 at 2:07 PM, Napillo said:

Yes, the smaller tanks can jettison at a pretty quick clip, and if you're loading on the large tanks, you're taking too much fuel.

I noticed that the 800 L tank could be jettisoned at about 500 km/h but the 1100 L tank could be done only at about 430 km/h, which was a bit annoying in the PVP match.

[Dr_Pavelheer]

@dock999 I'm pretty sure it's about Mach, not airspeed. As you approach speed of sound the way air flows around the aircraft changes, which means things like bombs, missiles, tanks might not necessarily separate safely from the aircraft above certain speeds. Take a look at photos of external fuel tanks carried by Su-24, they have little wings in the front to make sure they don't hit the aircraft when jettisoned

Also airspeed in the JF-17 is measured in knots, not km/h, to be more precise by default it shows KCAS, Calibrated Airspeed in knots

[dock999]

Thanks for the excellent input.

[MrBlob]

On 12/11/2023 at 2:50 AM, DSplayer said:

Unfortunately, it's a limitation and you'll have to slow down to jettison your tanks. Max speed is roughly Mach 0.9 iirc.

0.8 for the large tanks, 1.0 for small tanks. 

[jubuttib]

On 12/15/2023 at 6:30 AM, dock999 said:

I noticed that the 800 L tank could be jettisoned at about 500 km/h but the 1100 L tank could be done only at about 430 km/h, which was a bit annoying in the PVP match.

Are you sure you're talking about "km/h" and not knots? 500 km/h is barely above the speed where you can put down your landing gear...

[dock999]

On 2/20/2024 at 11:02 PM, jubuttib said:

Are you sure you're talking about "km/h" and not knots? 500 km/h is barely above the speed where you can put down your landing gear...

Someone had already pointed it out. Now I realize the dropping tank is more about Mach Number rather than Speed Number.

[Tiger-II]

It's both. At high altitude/Mach number, CAS is lower, relatively, so the Mach limit applies.

The limit is built into the jettison function. It's not an aerodynamic limit but a technical one built into the system.