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L-39 manual errors & typos


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1. K maks is an aerodynamic quality.

For L-39 Kmaks is 10.

 

So "К maks." has to be changed in the translated manual into the english equivalent: "E" or "glide ratio" or "lift-to-drag ratio" or "finesse". And the unit "km", as shown in the forced landing table, for this value would seem wrong to me.

 

2,3 Lglide is a gliding distance. Hflight is an initial altitude from which glide is started.

HouterNDB is a control altitude over outer NDB, normally 1 km.

 

Thank you for your clarification. I think this concept should be made clear in the manual. I personally continue to believe, however, that there is an error in reasoning:

 

Unbenannt1.JPG.6bfda9605e584057fa8524a5c5aa47a8.JPG

 

LGlide = (H1-H2)*E

 

LGlide is maximum possible gliding distance.

H1 is the initial altitude from which glide is started.

H2 is aircraft altitude at the end of glide, normally at an altitude of 1 km above outer NDB.

E is the finesse (distance forwards divided by distance downwards) for the L-39, this value is 10.

 

Aircraft is 15 km away from emergency airfield. H1 = 2000 m, H2 = 1000 m, E = 10. LGlide = (2000 m - 1000 m) * 10 = 10.000 m.

LGlide is just 10 km (maximum possible gliding flight). Based on this calculation, pilot is sure that landing is impossible.


Edited by Lino_Germany

Kind regards,

 

Lino_Germany

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If Kmaks is an aerodynamic quality the unit "km" is wrong in the table. If my translation is correct Kmaks is "list-to-drag ratio" and also "glide ratio" and that would be equivalent to E. So if Kmaks is E then 10 would mean that L-39 (with gear retracted, flaps at 0 degree, v=300 km/h) can glide 10 km with 1000 m loss of altitude. For our example L-39 landing would be possible because H1 = 2000 m. L-39 with E = 10 could theoretically glide 20 km at an altitude of 2000 m AGL at start of gliding.


Edited by EagleEye

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If Kmaks is an aerodynamic quality the unit "km" is wrong in the table. If my translation is correct Kmaks is "list-to-drag ratio" and also "glide ratio" and that would be equivalent to E. So if Kmaks is E then 10 would mean that L-39 (with gear retracted, flaps at 0 degree, v=300 km/h) can glide 10 km with 1000 m loss of altitude. For our example L-39 landing would be possible because H1 = 2000 m. L-39 with E = 10 could theoretically glide 20 km.

 

Thanks for your prompt reply. I agree completely with your argumentation.

Kind regards,

 

Lino_Germany

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  • 1 month later...
  • 1 month later...
  • 1 month later...

Del.


Edited by YoYo

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Why wouldn't there be...? It's obviously a bug.

 

As for the explanation, wide beam/narrow beam isn't really applicable here. That's how it might work on other planes where you have these light separated and with different lenses, but L-39 has only one reflector with different fillaments inside the lamp (and there's also a restriction of using the landing lights on ground). You can't change the illumination pattern (e.g. make it narrower) by turning up the power, that's why the real thing say "larger all-around pattern". That's all there is to it.

 

Not necessarily. If the filaments are placed in different locations along the longitudinal axis you can get different beam convergences by relocating the light source by only a short distance.

 

http://lh5.ggpht.com/_Ii1ukGkfijY/Sqepo6mi3ZI/AAAAAAAABIY/1pSHGvw1b4o/clip_image0043.jpg

 

With the addition of non-symmetrical reflectors and lateral source displacement a great many changes to the light can be accomplished still with fixed reflector geometry. This is how classically automobile headlights achieve high beam operation. If I were the engineer in charge of the landing light reflector and filament placement I would make the landing light rather narrow beam, aimed down, and converging at 1000' or so. The taxi light would be wider beam, aimed level and converging at 100-200'.

 

http://www.reaa.ru/cgi-bin/yabbA/YaBB.pl?num=1339089205

The lamp looks like a laterally-displaced filament symmetrical reflector type (the filaments might be at different longitudinal positions for different beam width but I can't tell by looking). I assume the filaments are installed above/below such that the landing light is aimed downward (ideal is landing AOA + glide slope). Remember that the filament on top is reflected downward and the filament below reflected upward.

 

My guess is that the singular filament is used for the taxi light and both filaments are used for the landing light which doubles the heat produced in the lamp. And of course the filaments can be different powers.

 

The changeover from landing to taxi lights in an L-39 can be seen here

It's apparently part LFSM-28-200-130 which is a 28V 200W/130W "PAR 46" aviation bulb at 135,000 and 13,500 candlepower respectively.

 

Most if not all DCS landing-taxi lights range between "embarrassing" and "development placeholder". No attempt was made to replicate the color, brightness, azimuth fade, distance fade, range, etc. of the real things. The engine is capable of a lot of nuance but the effort and artistry of the creators is absent.

 

For example the default lights illuminate an area of about 5,000m2 equal to noon brightness or about 5 million watts power. Considering the real lamp output is 400W combined that's a failure of about 4 orders of magnitude. Brightness is a subjective scale but roughly logarithmic and so that should seem 1/4 as bright as daylight. The lamps are also producing 90 degree beam widths which is insane, 8-12° is much more normal. Landing lights rarely illuminate more than the width of the runway at 50-100' AAL on final. 40 degree isn't uncommon for taxi. LED retrofits (which I'm sure lots of modern L-39s have) can be much brighter. The original Soviet lamps should provide the impression of a vague ghostly yellow haze that's barely better than no lights at all and make you very happy for special reflective yellow paint.

 

---

 

The manual describes during bombing and rocket attacks to set the ASP distance to minimum. This makes no sense to me. Surely setting the ASP distance to maximum (800m) is intended instead. Otherwise the practice of calculating the B-f fictitious base size is wasted effort.

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The manual describes during bombing and rocket attacks to set the ASP distance to minimum. This makes no sense to me. Surely setting the ASP distance to maximum (800m) is intended instead. Otherwise the practice of calculating the B-f fictitious base size is wasted effort.

 

I assume the ASP minimum is to unclutter the centre of the recital when aligning the centre 'spot' with the target during the initial 60-120° roll onto the target.

 

For Unguided Rocket Delivery ED's manual correctly describes how the ASP distance is set to maximum at the same time as the 'Safety Trigger' is taken off during the dive onto the target.

6. Flip the combat trigger down [LCtrl+Space], enter the maximum distance into gunsight [;] As a result, aiming reticle starts moving, reacting on aircraft maneuvers. Align aiming grid center with target’s center.

For Bomb Delivery,

 

There is a diagram in the Russian L-39 manual that looks to show the ASP distance being set to maximum during the dive onto the target (in the same way as for rockets), however as I don't read Russian I can't be sure I've interpreted it correctly (the altitude minimums match those to avoid bomb fragmentation).

 

However the L-39ZA English translation describes monitoring dive angle, speed, altitude and putting the recital on target but makes no mention of adjusting the ASP range during a bombing run.

 

This second description is close to ED's description and I can't say if it is incorrect or not, so is best left to feedback from real pilots.

 

attachment.php?attachmentid=142552&stc=1&d=1466045150

L-39AttackRU.thumb.JPG.959c26dd28a6d2414994a96de67dc8b4.JPG


Edited by Ramsay

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OK I see the logic here.

 

Rockets: There is a set firing distance so GYRO and set calculated base value. Minimum grip on turn in for damping, maximum grip before firing.

 

Bombs: The concept of visually framing the target is completely out the window. Set sight to FIXED. There's no point to using a calculated base size since you won't be using it. Minimum grip ensures the movable sight elements are clear.

 

Cannon: Same as rockets.

 

Gun pods: Same as cannon except use FIXED sight throughout. Grip maximum throughout the attack since benefit from grip minimum is absent due to FIXED being used.

 

Missile: Similar to gun pods.

 

In all modes it must be remembered the minimum and maximum sight diameters may mean that not all target sizes can be framed at the desired firing distance. E.g. 2000m R-3S shooting would require the target be no less than 35m wide. A B-52 would require a 22.6m fictitious base for 800m fiction range.

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  • 5 months later...

pg. 152 says this about the RKL - 41 :

 

"The RKL-41 is enabled by the BATTERY, 115V INVERTOR I, 115V INVERTOR II, and RDO CBs located on the main CB panel"

 

In-sim i can get reception on the RKL-41 with battery switch flipped on, but the ADF needle requires battery + only one inverter, and no need to flip the RDO CB switch.


Edited by hamzaalloush
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Hello, I'm really enjoying the L-39.

 

Page 131, regarding the VD-20 Barometric Altimeter:

------

Figure 109: VD-20 barometric altimeter

 

1. Outer scale, indicating altitude in meters

2. Inner scale, indicating altitude in kilometers

3. Barometric pressure window

4. Barometric pressure / QFE adjustment knob, for setting the altitude pointers to “0”

5. Pressure correction indexes, for landing at high altitude airfields, where pressure is less than 670 mmHg. The indexes are moved by the knob.

-----

 

Outer scale is not meters, the numbers are "meters x 100" and the tick marks are "meters x 10".

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  • ED Team
Hello, I'm really enjoying the L-39.

 

Page 131, regarding the VD-20 Barometric Altimeter:

------

Figure 109: VD-20 barometric altimeter

 

1. Outer scale, indicating altitude in meters

2. Inner scale, indicating altitude in kilometers

3. Barometric pressure window

4. Barometric pressure / QFE adjustment knob, for setting the altitude pointers to “0”

5. Pressure correction indexes, for landing at high altitude airfields, where pressure is less than 670 mmHg. The indexes are moved by the knob.

-----

 

Outer scale is not meters, the numbers are "meters x 100" and the tick marks are "meters x 10".

 

Thank you. This typo will be corrected.

Amat Victoria Curam.

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Control Stick

 

Hi all. Anyone know how to remove the Stick and Throttle in the L-39za I can do it in the C version but not the ZA version. Does'nt seem to have the option in the control settings. Great airplane to fly.

 

Many Thanks.

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Hello,

 

Page 193.

 

Regarding navigation into and entering a landing path:

 

Figure 153: Landing pattern using GLIDE PATH and LANDING modes

1. Descent in cloud penetration mode;

2. Altitude - 600 m. D= 21±3 km. end of «GLIDE PATH» mode;

3. Altitude - 600 m. D = 15 km. speed - 330 km/h – retract landing gear;

4. Speed - 280 km/h – extend flaps at 25º.

5. Altitude - 600 m. D = 12 km. Radio glideslope entry point.

6. Altitude - 300 m. D = 6 km. speed - 280 km/h – extend flaps at 44º.

7. Fly over outer NDB, speed - 260 km/h, altitude - 200 m.

8. Fly over inner NDB, speed - 230 km/h, altitude - 60 – 80 m.

 

Should be extending gear at this point, not retracting.

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  • ED Team
Hello,

 

Page 193.

 

Regarding navigation into and entering a landing path:

 

Figure 153: Landing pattern using GLIDE PATH and LANDING modes

1. Descent in cloud penetration mode;

2. Altitude - 600 m. D= 21±3 km. end of «GLIDE PATH» mode;

3. Altitude - 600 m. D = 15 km. speed - 330 km/h – retract landing gear;

4. Speed - 280 km/h – extend flaps at 25º.

5. Altitude - 600 m. D = 12 km. Radio glideslope entry point.

6. Altitude - 300 m. D = 6 km. speed - 280 km/h – extend flaps at 44º.

7. Fly over outer NDB, speed - 260 km/h, altitude - 200 m.

8. Fly over inner NDB, speed - 230 km/h, altitude - 60 – 80 m.

 

Should be extending gear at this point, not retracting.

 

Already corrected. Manuals will update later. Thank you.

Amat Victoria Curam.

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  • 7 months later...

Maybe this is not an error...

 

For unguided rockets delivery in L-39C you can read in page 214:

 

5. Set fictitious target base

6. Set the GYRO-FIXED switch to the GYRO position [LShift+J]

7. Enter the minimum distance into gunsight [.]

...

 

but for rockets firing in L-39ZA is stated in page 257:

 

4. Set the fictitious target base

5. Set the GYRO – FIXED switch to FIXED [LShift+J]

6. Enter the minimum range into the sight [.]

...

 

Do we have to start with FIXED or GYRO? Is it different for L-39C and L-39ZA?

 

Thanks.

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  • ED Team
Maybe this is not an error...

 

For unguided rockets delivery in L-39C you can read in page 214:

 

5. Set fictitious target base

6. Set the GYRO-FIXED switch to the GYRO position [LShift+J]

7. Enter the minimum distance into gunsight [.]

...

 

but for rockets firing in L-39ZA is stated in page 257:

 

4. Set the fictitious target base

5. Set the GYRO – FIXED switch to FIXED [LShift+J]

6. Enter the minimum range into the sight [.]

...

 

Do we have to start with FIXED or GYRO? Is it different for L-39C and L-39ZA?

 

Thanks.

 

It's a mistake, I'll fix it. It should be so for both aircraft: Set the GYRO-FIXED switch to the GYRO position [LShift+J]

Amat Victoria Curam.

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  • 5 months later...
  • 3 months later...

I just got this beauty during this sale. Yesterday I read the section with the "Circle Pattern Flight". Shouldn't this be named circuit pattern flight? You really don't fly a circle in that particular pattern. It also has some other weird words and errors in it.

 

Some examples:

It used for practicing takeoff, turns, landing approaches and landing, as well as for visual

landing approach on airfields without instrument landing system installed. Circle pattern

altitude for standard landing approach is 600 meters. When landing on unknown airfield,

pilot performs approach and landing using basic parameters.

->

It is used for practicing takeoffs, turns, visual landing approaches and landings. The circuit pattern

altitude for standard landing approaches is 600 meters. When landing on an unknown airfield,

the pilot performs approach and landing using basic parameters.

 

Underfly is fixed by pulling, for that RPM should be increased so that airplane maintains speed and

descends towards flaring point with constant pitch angle.

Small overfly is fixed by reducing engine RPM. If approach is performed with overfly which cannot be

fixed by RPM reduction, perform missed approach procedure.

 

"Underfly", "Overfly"? Are those real words? I think a steep or shallow glide path is the key word here. These little things might confuse new pilots.

I am not a native speaker so i might be wrong. I never had any trouble to understand the A10 or F5 manual.

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  • 1 year later...

Hello!

 

on page 4 of the Quick start guide:

 

"Engine should be started from the front cockpit, because STOP latch, which allows moving the throttle from the STOP to the IDLE and further, located on the front cockpit throttle only."

I would rephrase this:

"The engine should be started from the front cockpit only, because the STOP latch, which allows moving the throttle from the STOP to the IDLE position and further, is located on the throttle lever in the front cockpit.

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