Help needed for the SU-27

[Maraudeur]

Hi everybody out there.

After many bounces I've been redirected to your homepage by Han and Yoyo, two members of Eagle Dynamic's staff. They told me they were too busy to help me.

To avoid repeating always my original message, here is a copy of it:

Hi, I've been redirected to your home page by Airforce.ru.

I had many question to ask, and they told me that I should contact you.

I've so registered myself on your homepage as "Maraudeur" but I still cannot post any question.

Nevertheless, here is a part odf the e-mail I sent tou Airforce.ru. May be you could help me, by advance, thank you.

Let me introduce myself:


I am a french "virtual pilot". I am the leader of the french virtual
 squadron knwon as the "92nd Kodiak Air Force" a party of 16 "pilots"
 members of the larger "3rd Wing", a fellowship of about 90 virtual
 pilots. This squadron uses the extraordinary SU-27 simulated in Lock On,
 the great game from Eagle Dynamics (also included the scheme paint of
 the Russian Knights).
 

We try to fly this plane the most reallistic way possible. We've
succeeded in finding many documentations, plates, schemes and
blueprints, but we still lack of some informations. This would be very
king of you if you could expalin us some of the REAL PROCEDURES in
use with the SU-27.
   

In particular we'd like to know (considering the "normal" use of the
SU-27, not for the airshows of course):

 - Do you taxi with the flaps extended or not. If not, when do ou extend
 them.
- If the Vr speed of 200km/h is the correct one, with the Vlof depending
 on the load of the aircraft.
- Do you take off RPM 100% or in wich case do you use the after burner
 (depending on the weight of the aircraft and the lenght of the runway)
- Is the pitch of 10° the correct one for rotation and initial part of
 the take off
- When do you retract the flaps (speed or height), and wich type of
climb do you use: pitch of 10° or 15°, indicated air speed or Mach number
- What is the conjuction point (for example, we generally use Mach 0.7
for cruise)
- During the intermedate approach, what is the correct sequence for
extending the elements (flaps, gear, airbrake...)
- Do you perform the final approach with the airbrake extended
- I've read that the angle of acttack on final was 10°, but we found the
AoA 8° more comfortable. What is the correct value.
- Do you retract the flaps once the runway is vacated, or while taxiing
 back.

I would have many other questions, but I wouldn't like to be annoying...
I am also building a SU-27 cokpit linked with my computer and with
LockOn. Therefore I have a full bag of questions. This is the reason why
I've been obliged to learn about the Cyrillic alphabet, and I've
succeeded in finding a very rare "Russian to French" dictionnary. But I
must admit that I cannot speak or read fluently you language (yes, I
know, shame on me...)

By advance, thank you to take time to answer my questions, or at leats
to give me some trcks where to find these informations.

Спасйбо

Here it is,  , I admit that it's a bit long but I have so many questions....

I forgot to tell you also that in real life I work as a Synthetic Flight Instructor for
the French Air Force, so do not hesitate to be somehow "technic" 

Once again, thank you to those who would accept to help me, and my virtual squadron....

[skry]

Hi, Maraudeur

I'll answer several questions. I think it's not a doctrine, other squadrons do it in another way because, you know, it's not a real Su-27 
1. Yes, we always taxi to the runway with the extended flaps
3. It depends on the mission. More often our take off RPM is 92% with a half-fulled tank, sometimes it is 100%, but we never use afterburner.
4. Yes, 10° is the maximum pitch for take off (not only for initial part), but it may be less (depends on RPM)
5. 300 km/h or 100 m
7. First of all airbrake and then gear, flaps extend automatically with gear
8. Yes
9. 8° (not AoA but pitch) is correct too but it's more professionally to land with 10° pitch
10. Yes, we retract flaps after the runway leaving.

May be my friends have something to add.

Good luck.

[Maraudeur]

Thank you for taking time to answer my questions  .

Concerning the 8° pitch on final, you mean that you do not use a constant AoA during final? It's a bit amazing because if you use a constant pitch, the angle of attack will be different, depending of the weight and the drag index of the aircraft.

As far as I know, fighter airpalnes use a constant AoA for the final. To do so the use a constant pitch, and this is the speed on final that if calculated to match the constant AoA (in fact, like LockOn's flight director does, prescribing a speed on final depending on the weight od the load of the aircraft).

Concerning the question n°5: my firts intention was to know the prescribed After TakeOff Safety Height, the height to wich planes are supposed to climb after takeoff prior to accelerate to the V2 speed, to then retract the flaps and resume normal climb.

[An.Petrovich]

Maraudeur, skry means the 8-10° pitch at the touch-down moment.
The AoA must not be a constant on final, if the airspeed is declining. So, if you have about 50% fuel, the AoA is on the increase from ~0° (the level flight at 400km/h, flaps and gear down, airbrake on) to ~7...8° before runway (240...260km/h at 10...15m altitude).

[skry]

2 Maraudeur
I could say that height in this case is the second point to take you attention. First, you ought to control airspeed before retracting flaps. I think you understand what could happen if you will be, as you said, on the safety height but with minimum speed.

[An.Petrovich]

Maraudeur, what does it mean - "Synthetic Flight Instructor"?
Do you flight real airplanes?

[Maraudeur]

To Petrovich: "Synthetic" means that I teach pilots to fly on "real" flight simulators from the French Air Force. As so, I am not employed as a pilots by the FAF. But, to be able to teach properly, I've followed the same course as the french pilots, exept that I flown on the sim what they flown in real. Neverltheless, I also go regularly in "real" flight to remain "linked" with the reallity.

To Skyr: in fact, every real plane has got a safety height given by the munufacturer of the aircraft. Thos height is used in case of failure after V1. At this speed, whatever may happen, the planed is supposed to pursue the takeoff because it is impossible for it to stop on the runway. Then, the plane is supposed to climb at an optimal single engine speed, that depends on the aircratf's configuration (gear up or down,, payloads jettissoned or not). The pilot is supposed to maintain these settings up to to the prescribed safety height. Reaching this height, the pilots continues to climb but reduces the pitch to accelarate to the optimal single engine speed with everything retracted. This speed matched, the pilots retracts the flaps and resumes the climb to the Minimum Safety Height of the arfield to then level off and deal with the failure in safety environement. The "After TakeOff Safety Height" (the 1st one i explained) garantees that the pilot will be able to accelerate with a climb slope that will grant him clearance from the obstacles. Sorry for having been a bit long  . I was just wondering wether or not someone was aware of these 2 datas: "after takeoff safety height" and minimum speed for flap retraction...

[Maraudeur]

To Petrovich (again): As far as I know, every modern aircraft uses a constant AoA for the final approach. From this way of flying is deduced the energy vector. This AoA is given by the manufacturer. it is an equilibruum between the speed, the rate of descent, the pitch and the thrust.
The trick is to calculate the correct speed on final, depending on the weight and the payload of the aircraft. Then with the basic final pitch displayed, you have the conjunction between the AoA, and the rate of descent. For example, with a rather light SU-27, you calculate a final speed of 240Km/h, with a basic pitch of 5° you get an AoA of 8°, leading to a rate of descent of around 5m/s

[Maraudeur]

I also found this on a documentation, but as I'm not really good in russian, I'm not sure of the translation:

Взлёт и посадка производятся при фиксированных в отклонённом положении носках крыла и флаперонах.
Во взлётно-посадочное положение флапероны отклоняются симметрично на угол 18° и от этого положения для управления по крену отклоняются вверх на 27°, вниз на 16°. Носки крыла выпускаются на 3/4 полного отклонения (по шкале индикатора положения носков).
При заходе на посадку и посадке расходы ручки управления небольшие, запас хода ручки по тангажу при касании самолета составляет 3/4 хода.
При выпуске и уборке флаперонов во взлетно-посадочное положение и обратно и изменении оборотов двигателей от МАЛОГО ГАЗА до МАКСИМАЛА, при создании скольжения до 0,5 хода педалей, изменение продольной балансировки практически отсутствует.
Выпуск носков крыла в посадочное положение вызывает момент на пикирование, для парирования которого необходима перебалансировка по усилию ∆Рв = 1 кг.
При отказе СДУ завершение полета и выполнение посадки возможно на режиме ЖЕСТКАЯ СВЯЗЬ, при этом полет целесообразно выполнять при Кш = 1,0 на скоростях 500-600 км/ч. Допустимый угол атаки при этом составляет 10°.
Взлетно-посадочные характеристики и их зависимости от различных факторов приведены в номограммах (рис.6, 7, .
Во взлетно-посадочной конфигурации αдоп ≈ 20°.

Maybe some one could help me...