Hi Mike, this whole little series of exlpanations and limits, along with viewing actual guage interactions , and engine audio, from start up to start down, is great. Hope this resource remains on YT long into the future, for technically minded. I noticed on your start up vid that around N1 ~ 50% that a third winding up sound kicked in. This vid tells me that is acutually transmission/ over run clutch/mast/rotor head/ tail drive noises as it persists even though turbine spools are near stopped. Sounds like ready for major bearings overhaul time! Of course no oil getting pumoed at this point. Surprised the design does not also include an electrical driven boost oil pump interlock, until all rotating components are at full stop. Appreciate the work you did on this.
The TOT increasing as the Gas Producer (N1/Ng) gets closer to zero % is because of the residual heat, which is now trapped without the cool air getting sucked into the engine via the compressor. Until Ng / N1 / Gas Producer reaches zero you need to make sure that fuel is not re-introduced via the throttle not remaining in the closed position. If fuel is re-introduced without sufficient Gas Producer RPM, there will be a rapid spike in TOT.
If you have a spike in TOT during shutdown you would press the starter and ensure the throttle is fully closed. Pressing the starter button will spin up the compressor & gas producer, sucking in cool air, cooling your TOT. Pressing the starter button will also activate the igniter, and any residual fuel, but with the throttle closed there won't much of any fuel to burn. The key aspect of pressing the starter is too suck in cool air and to get rid of the hot gases.
I too notice the TOT creeping up near the end, but I wouldn't really call it "spiking"...is it caused by residual heat-soak with decreasing cool airflow to remove it? Maybe Mike can explain. Also, why (and how) would there be an "accidental introduction" of fuel during spindown?...and how would you know this?...and why would you press the starter button at that point?...wouldn't that start the ignitors, igniting the fuel and be the definition of a hot-start? Inquiring minds need to know!
All good, but after putting the throtle in cut off position for shutting off you miss to shitch off the generator shitch. Isn´t this what the manual says?
Hi Mike, this whole little series of exlpanations and limits, along with viewing actual guage interactions , and engine audio, from start up to start down, is great. Hope this resource remains on YT long into the future, for technically minded. I noticed on your start up vid that around N1 ~ 50% that a third winding up sound kicked in. This vid tells me that is acutually transmission/ over run clutch/mast/rotor head/ tail drive noises as it persists even though turbine spools are near stopped. Sounds like ready for major bearings overhaul time! Of course no oil getting pumoed at this point. Surprised the design does not also include an electrical driven boost oil pump interlock, until all rotating components are at full stop. Appreciate the work you did on this.
great video Mike, look forward to seeing you progress to turbine aircraft
The TOT increasing as the Gas Producer (N1/Ng) gets closer to zero % is because of the residual heat, which is now trapped without the cool air getting sucked into the engine via the compressor.
Until Ng / N1 / Gas Producer reaches zero you need to make sure that fuel is not re-introduced via the throttle not remaining in the closed position. If fuel is re-introduced without sufficient Gas Producer RPM, there will be a rapid spike in TOT.
If you have a spike in TOT during shutdown you would press the starter and ensure the throttle is fully closed. Pressing the starter button will spin up the compressor & gas producer, sucking in cool air, cooling your TOT. Pressing the starter button will also activate the igniter, and any residual fuel, but with the throttle closed there won't much of any fuel to burn.
The key aspect of pressing the starter is too suck in cool air and to get rid of the hot gases.
Fantastic vid! These MD500's look like a blast to fly!
nice man! thanks heaps for this vid, just a quick question, whats your fave heli?
80% of the air induced into the engine is used for cooling and only 20% for ignition, if my memory is correct.
I too notice the TOT creeping up near the end, but I wouldn't really call it "spiking"...is it caused by residual heat-soak with decreasing cool airflow to remove it? Maybe Mike can explain. Also, why (and how) would there be an "accidental introduction" of fuel during spindown?...and how would you know this?...and why would you press the starter button at that point?...wouldn't that start the ignitors, igniting the fuel and be the definition of a hot-start? Inquiring minds need to know!
Could you explain the throttle settings, when you use them, and if they are the same for turbine and reciprocating engines?
All good, but after putting the throtle in cut off position for shutting off you miss to shitch off the generator shitch. Isn´t this what the manual says?
what's the chirping that starts at around 3:29?
Good instructional video btw.
Did you notice your TOT creeping-up on that shut-down
Yes me too Notice that TOT is not decreasing at the end it got stucked
TNX clarifications! Fly Safe!
I thought a turban was something an Indian wore on his head.