MIG-21 BIS flight time

[Frenetique]

Hello everyone !

 

I have a quick question regarding the MIG 21 BIS flight time at low fuel states. :helpsmilie:

 

Let me explain: in the manual it is said that the red "caution" light "450L" means (obviously) that the fuel state is at ~450L and that it allows 12 minutes of flight time.

 

My question is, at which engine regime ? 12 minutes means nothing since the consumption is altitude and speed dependant (throttle level also).

 

 

So are those 12' for a given engine regime or are they any thumb rules ?

 

Thanks in advance.

[howie87]

You can use this chart to give you some idea. By my calculations, carrying 8x FAB 100 bombs at 500m AMSL 450L would give you closer to 10 minutes of flight time at the MiG's max endurance speed of 480km/h ;)

 

In a clean jet you'd get around 14 minutes.

 

12 sounds about right as a ballpark figure.

 

480km/h indicated is the max endurance speed for the MiG-21 at all altitudes.

 

http://forums.eagle.ru/showpost.php?p=2154839&postcount=16

[Darkwolf]

when the 450L light goes on, it's too late to calculate fuel time. You MUST land IMMEDIATELY. recommended fuel reserve for landing is 700L, which include 2 go around. At 450L, you should stop calculating and look for an highway, if you aren't near your base.

 

check out this page

 

http://www.digitalcombatsimulator.com/en/files/1432826/

[Frenetique]

Thanks for the answers guys ! That's awesome !

 

@Darkwolf: I know that you have to land don't worry. The problem was that I wasn't sure if I would make it or not to the runway. I made a quick mental calculus based on the golden 12 minutes and got almost there (had to eject, engine shut down at ~300m from the runway).

 

Another question for howie87: I don't get the difference in term of application from the "maximum range" tab and the "maximum endurance" tab. I see that it's not the same from the values but don't get the philosophy behind it. Maximum endurance meaning what ? Maximum fuel at arrival ?

[NeilWillis]

Maximum endurance is pretty self explanatory - the longest time. It means the maximum time you can stay airborne, and disregards the distance you can fly (maximum range).

[LeGordian]

Another question for howie87: I don't get the difference in term of application from the "maximum range" tab and the "maximum endurance" tab. I see that it's not the same from the values but don't get the philosophy behind it. Maximum endurance meaning what ? Maximum fuel at arrival ?

 

Endurance = time you can fly until you run out of fuel

Range = distance you can fly until you run out of fuel

 

There are speeds either maximizing endurance (the speed with which you will fly the longest time possible) or maximizing range (the speed with which you will fly farthest). They differ because the former aims to minimize fuel flow only, which might happen at a very small speed and not get you very far, while the latter is a the optimal compromise between fuel flow and speed.

 

EDIT: I was typing to slowly :D

Edited November 5, 2015 by LeGordian
Double post

[Frenetique]

Perfect ! I understand. :smartass:

 

Thanks guys, you're awesome ! :thumbup:

[HugePanic]

RTFM:

 

"Longest range speed: 650-600km/h IAS (decreases with altitude)

Longest flight duration speed: 480km/h IAS (doesn’t depend on altitude)"

[WildBillKelsoe]

When that light comes on, I drop all stores, climb to maximum altitude while turning to nearest friendly RSBN station.

If you have problems getting back, it is always good practice to write down joker and bingo. That way you never have to worry about fuel.

 

Sent from my SM-T231 using Tapatalk