gambit
PROFESSIONAL
- Joined
- Apr 28, 2009
- Messages
- 28,569
- Reaction score
- 148
- Country
- Location
The Boeing 737 Max fiasco is appropriate here.@gambit
sir can you add anything regarding the feasibility of integrating Lyulka AL-21 to F-5 structure??
another question is that if it's possible for jet engines to work in their 10% of max out put power or not?
An aircraft is a working structure of compromises, so when you see an aircraft flying, you should know that literally everything that made the aircraft flight capable have been designed and manufactured with a measure of structural tolerance or 'wiggle room' or leeway in mind.
wig·gle room
capacity or scope for negotiation or operation, especially in order to modify a previous statement or decision.
What it means is that there is a tolerance or range of operational capacity that should not be crossed. When you see an aircraft in flight, every tolerance or range of operational capacity have been made relatively harmonious with each other. It is not perfection. The fact that there are ranges of tolerances means the system is imperfect.
When Boeing changed to the new engine in the 737 Max, the new engine upset all the balances. With the new engine, the aircraft have a greater RATE of pitch change and a higher angle-of-attack (AOA) sooner after nosewheel up. So Boeing created a software compensator (not fix) for a hardware issue (not problem).
The point is not about the public relation disaster but about that out of balance condition created by the new engine.
The new engine may fit in the F-5's engine bays, but what about performance in flight? Airfoils are designed specifically for a range of airspeed and altitude. The new engine may make the jet faster and accelerate rate higher, but that could also affect the departure from controlled flight envelope.
https://www.cnatra.navy.mil/local/docs/pat-pubs/P-1216.pdf
Every aircraft have a figure 2-9. That bar in the middle of the chart will be different in location and tilt, but essentially, every aircraft have that chart.Departure from controlled flight is that phase of flight during which the aircraft transitions from controlled to uncontrolled flight (Figure 2-9)...
It literally took yrs for the F-16 to change the opening of the intake and that was required with the new engine and you can see the intake difference here...
Pratt Whitney top
General Electric bottom (larger)
What if the F-5's current intake shape and size is too restrictive in airflow for the AL-21? Now you have to modify the F-5's intakes.
Am not saying it is technically impossible, but there are ramifications that will take yrs to resolve.