H2O pump sound activates with switch

[Highwayman-Ed]

From what I’ve read in the NATOPs documentation for the AV-8B NA the H2O system is armed with the switch, but only runs when criteria are met. See the below excerpt from this document;

 

"Take Off setting;

Water flows when the throttle is set above 95 percent rpm for the -406 engine and 105 percent rpm for the -408 engine.

 

After takeoff, water continues to flow until airspeed exceeds 250 knots, water is depleted, OFF is selected, or the throttle is moved below 95 percent rpm for the -406 engine or below 103 percent rpm for the -408 engine."

 

In DCS, the pump noise is heard as well as an increase in engine RPM and JPT whenever the switch is moved into either the TO or LDG position, but the water flow indicator and decrease in water volume functions correctly when the above parameters are met.

Edited December 2, 2017 by Highwayman-Ed
corrected grammar

[comie1]

Just because the pump is running doesn't mean water is being pushed in though does it? Not sure how it's supposed to work IRL but I kinda like the way it is because I don't forget to turn the pump back off :smilewink:

[fjacobsen]

True, but Engine RPM increases even when the "W" light is out.

I assume that engine ppower on is affected when the "W" light is on and thus indicates injetion of water at the higher throttle ranges.

[Highwayman-Ed]

True, but Engine RPM increases even when the "W" light is out.

I assume that engine ppower on is affected when the "W" light is on and thus indicates injetion of water at the higher throttle ranges.

 

Correct, currently it seems that turning the switch on gives the engine RPM boost regardless as to whether the water injection is active or not. The indicator light is working as expected however.

 

I also have no real life expertise as to exactly if I should hear the pump noise or not without the water flowing, I'm simply stating the difference in the experience in DCS and that stated in the NATOPs documentation about the difference between Wet and Dry operation.

 

Regardless, I LOVE the DCS Harrier, I just want it to be as great as it can be.

Edited December 2, 2017 by Highwayman-Ed

[Dave317]

When I turn the system on I notice an increase in jpt even if the water is not flowing. I've tried hovering until I've run out of water at which point I dropped like a stone and destroyed the gear.

Edited December 5, 2017 by Dave317

[robmlufc]

Correct, currently it seems that turning the switch on gives the engine RPM boost regardless as to whether the water injection is active or not. The indicator light is working as expected however.

 

I also have no real life expertise as to exactly if I should hear the pump noise or not without the water flowing, I'm simply stating the difference in the experience in DCS and that stated in the NATOPs documentation about the difference between Wet and Dry operation.

 

 

You should get an increase in LP RPM of about 3.7% when you select TO or LDG, even with no water flow.

 

I don't think the pump should fire up until you get to 95% throttle position, which trips a solenoid and allows bleed air to the pump but its been a while and I standby to be corrected.

[Zeus67]

Engine RPM is automatically increased by DECS when water is activated, but actual water flow depends on several variables.

 

It is very much like the RPM in your car engine that changes whenever you turn on/off the AC.

[fjacobsen]

I just read somewhere that when the water switch is turned on (TO / LDG), fuel flow is also increased a tad to increase Idle RPM.

Thats probably what we hear and see. Water is added above 95% RPM in TO setting (a bit more complex in LDG, but almost works similar).

 

So assumingly no bug present.