Doing loops

[Mt5_Roie]

So I've gotten the aircraft started now a couple times and enjoy flying her. So I've been trying to take her for a few manuvers. It seems that when I pitch her up for a loop she starts buffering and at the top of the loop kind of slides sideways instead of looping. Is there some trick or throttle play I should know about to loop her?

 

I usually start out in a 10 degree dive to gain speed. Then I start pulling back slow and raising the nose. Should I be doing it different in this jet?

[vladd148]

What's your entry speed? If you take a look at the manual, the entry speed recommended for a loop is 650km/h.

[Mt5_Roie]

Usually around 700km/h....seems like at the top of the loop it just loses control and departs.

[vladd148]

What's the G-load during the loop? It could be that you are either pulling too quickly or too slowly. I don't remember the recommended number in the manual, but anything around ~4 sounds reasonable to me.

[Mt5_Roie]

Is there a guage for G load or is it like the Mig-15 that I have to display it on screen?

[vladd148]

Is there a guage for G load or is it like the Mig-15 that I have to display it on screen?

 

The accelerometer is right below the landing gear level. Remember, and this is applicable to real life, that in order to prevent stalling or buffeting during aerobatics, you've got to take into consideration the entry and exit speeds as well as the g-factor during the maneuver.

 

 

Here is the procedure for the inside loop straight from the manual:

 

Inside loop entry is performed at entry speed of 650 km/h with engine operating at takeoff RPM.

By slowly pulling the stick start climbing.

At pitch angle of 25-300 pull the control stick faster so that when pitch angle of 50-600 is reached, G-factor is 4-5 units. From this point pull the stick so that airplane angular velocity is maintained constant, and speed at the highest loop point (airplane is “wheels up”) is not less than 200 km/h.

In the upper point of the loop, check aircraft position and when the upper part of the instrument panel aligns with the horizon line, slowly reduce engine RPM to 90% and by slowly pulling the stick, start diving. The descending part of the loop is similar to split-S (descending half-loop). Gained altitude in the upper point of the loop is 1200-1400 m.

 

 

1. Loop entry – speed is 650 km/h, throttle is in the «TAKE OFF» position;

2. ADI – pitch angle is 50 – 600, G-factor 4,5 – 5 units;

3. ADI – сlimb angle is 900, airplane symbol rotates at 1800, speed is 400 km/h, G-factor 3,5 – 4 units;

4. Airplane in the «wheels up» position – check if speed is not less than 200 km/h, set engine RPM to 90%, G-factor - 1,2 units;

5. Angular rotation relative to the ground, absence of roll;

6. ADI – dive angle - 900 , airplane symbol rotates at 1800, speed is 380-400 km/h, G-factor 3 – 3.5 units;

7. ADI- dive angle 80 - 700, speed - 450 km/h, G-factor - 3 – 3,5 units, increase engine RPM to the takeoff value;

8. Loop exit. Speed is 650 km/h.

 

Ref: DCS L-39C Manual

[Mt5_Roie]

Yeah I had the manual open the whole time I was trying. I think I figured out the issue though. I had my pitch and my roll set up for my office joystick with deadline, but not the rudder. I think the rudder was causing some side sway and making issues. So I added a little deadzone to it and it worked nicely.

 

But since were on the subject of airspeed...I know the accelerametor has two reading. One is the true airspeed and one is indicated. For aerobatics which one should I used for entry and exit speeds? I would assume true airspeed, but wanted to double check.

[Gate-5]

I had the same problems with the immelmann because I didn't keep the G's up in the second half of the upwards loop. Now I end up above 210kmh when entering at something above 600kmh.

[grunf]

But since were on the subject of airspeed...I know the accelerametor has two reading. One is the true airspeed and one is indicated. For aerobatics which one should I used for entry and exit speeds? I would assume true airspeed, but wanted to double check.

Indicated.

[virgo47]

This is very good info, but it seems to be left out in the current version of DCS L-39 manual - why is that?

Anyway, I'd like to use L-39 for some aerobatics in a structured manner - but I can't find anything relevant to the L-39 aerobatics. At least nothing at the level of details shown above for the loop. Do you know about some list of figures and the recommended flight parameters for them? I know I can (and will) experiment, but I'd welcome any recommendations. DCS-specific or real-life based material, I don't care.

[Morpheus]

I lead an aerobatic L-39 team, generaly 60% fuel at the beginning of display as lead I set rpm to 95% (without modifying it) 300kts/555 km/h at start of loop, I use trim to always reproduce same parameters for wingmen. The figure passes easily,4G, 120/130 kts (220 km/h) at the top. Fine for me. Real team I represented gave me these parameters.

https://youtu.be/ayTcOFxiwxM?si=ktnALwE4Mg5KGRKe

Edited January 1, 2024 by Morpheus