L-39 not reaching cruise speed

[generaldeejee]

Hi, I don't seem to be able to reach the cruise speeds listed in the DCS manual:

 

a) engine operating at maximum thrust (n1hpc =106,8±1%)

at ground level km/h 702*

at 5000 m km/h 757*

at 6000 m km/h 760*

at 10000m km/h 737

 

I'm mostly flying in the 500-600's and never reach more as 700 km/h in a straight horizontal flight in a L-39C with full throttle, neutral flaps, no weapons and default fuel load. Is there something I must do to reach this 750 km/h cruise speed or is the cruise speed indicated in the manual too high?

 

Thank you in advance

[Sweep]

Neutral flaps meaning they're in the middle position? That might be a problem... ;)

[generaldeejee]

Neutral flaps meaning they're in the middle position? That might be a problem... ;)

 

I mean the top position, so totally flat (not extended)

[Kelevra]

Hi, I don't seem to be able to reach the cruise speeds listed in the DCS manual:

 

a) engine operating at maximum thrust (n1hpc =106,8±1%)

at ground level km/h 702*

at 5000 m km/h 757*

at 6000 m km/h 760*

at 10000m km/h 737

 

I'm mostly flying in the 500-600's and never reach more as 700 km/h in a straight horizontal flight in a L-39C with full throttle, neutral flaps, no weapons and default fuel load. Is there something I must do to reach this 750 km/h cruise speed or is the cruise speed indicated in the manual too high?

 

Thank you in advance

 

 

I just tried it to be sure.

@5000m

full throttle

neutral attitude (horizontal flight)

 

was reaching true air speed of 760km/h easily...

 

mind the 2 needles on the air speed indicator

fat one IAS

thin one TAS

 

the manual is talking in TAS.

[generaldeejee]

Thanks for checking it out, I was basing myself on the F-2 view speed. Trying it again while now watching the TAS needle I was indeed able to reach 750 km/h but to get that speed I needed to constantly monitor my attitude indicator and push down on the joystick every few seconds which is not maintable on the long term. Do you have any tips to keep this speed without too much input?

I just tried it to be sure.

@5000m

full throttle

neutral attitude (horizontal flight)

 

was reaching true air speed of 760km/h easily...

 

mind the 2 needles on the air speed indicator

fat one IAS

thin one TAS

 

the manual is talking in TAS.

[Yo-Yo]

Thanks for checking it out, I was basing myself on the F-2 view speed. Trying it again while now watching the TAS needle I was indeed able to reach 750 km/h but to get that speed I needed to constantly monitor my attitude indicator and push down on the joystick every few seconds which is not maintable on the long term. Do you have any tips to keep this speed without too much input?

 

Trim, trim and trim once again!

W.I. Ulianov-Lenin

[Kelevra]

Thanks for checking it out, I was basing myself on the F-2 view speed. Trying it again while now watching the TAS needle I was indeed able to reach 750 km/h but to get that speed I needed to constantly monitor my attitude indicator and push down on the joystick every few seconds which is not maintable on the long term. Do you have any tips to keep this speed without too much input?

 

Trim, trim and trim once again!

W.I. Ulianov-Lenin

 

 

As Yo-Yo puts it, trimming is the way to go :)

 

This training aircraft is not equipped with autopilot (as most trainers).

 

Students pilots in the pit are not there to take a nap but rather to learn the ropes.

 

Imagine that while the instructor is setting down the hood,

the student only had to set the autopilot on the required course / altitude... That wouldn't be very productive...

 

tip : Once you have find your correct cruising speed @ the max continuous % of thrust which is 99.6% RPM.(Eng manual p91)

 

then play with the trim to find the sweet spot that will require the less input from you part.