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scottb613

APU can start without battery ?

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Hi Folks,

While an abnormal procedure - I started the APU without having the battery on - which I would think should be impossible ?

Regards,

Scott

Edited by scottb613

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4 hours ago, scottb613 said:

Hi Folks,

While an abnormal procedure - I started the APU without having the battery on - which I would think should be impossible ?

Regards,

Scott

HI Scott,  managed to replicate your APU start, could only do with the Ground Power Unit ticked. That's with XFR and booster pump on.

bob

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Hi Bob,

Doh - I may have been messing with the GPU when that occurred - I'll confirm when I have a chance...

Wish we had some sound effect for the GPU - like the Hot Start TBM in XP - would help eliminate confusion...

Thanks for the feedback...

Regards,
Scott

Edited by scottb613

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2 hours ago, scottb613 said:

Hi Bob,

Doh - I may have been messing with the GPU when that occurred - I'll confirm when I have a chance...

Wish we had some sound effect for the GPU - like the Hot Start TBM in XP - would help eliminate confusion...

Thanks for the feedback...

Regards,
Scott

I was just thinking that last night..wish we had at least a power humming sound or something to represent the electric gpu!

Edited by chevelle505
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IRL, on most airports the GPU is directly connected to the airbridge or any other fixed ground equipment so you don't get any aural or visual feedback.

Furthermore I've seen a lot old 'real' GPUs which do make a lot of noise, but don't deliver any, or the correct power.

The only reliable source is the cockpit indication!

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16 hours ago, chevelle505 said:

I was just thinking that last night..wish we had at least a power humming sound or something to represent the electric gpu!

When we connect the stand's FEP to aircraft, we don't even know if the power is running ourselves from any audio cues, even when stood right next to it, it's only the indicator light on the FEP's control panel which will tell us that it is delivering power. We have to swipe our security pass on a control box near the air bridge too in order to get it working (since an active FEP connection costs £30 per hour at EGCC where I work), but since that just flips a lock switch to allow it to deliver power from a mains connection, there is no audible change when you do that.

Even then it can still be a bit finicky to know for sure that power is available since the FEP's plug and cable is pretty heavy and can sometimes drop out, or slip a little in the socket and stop the connection (especially on the Airbus A320/330 family, which has a stupid connector design), so as FDEdev says, it's really only the panel in the cockpit which can truly confirm that power is available. There's invariably an indicator light inside the aircraft's access hatch  where you plug the connector - depending on the aircraft type - but the power plug (or plugs, as in two of them on big aeroplanes like the A330) generally make the indicator light hard for us to see, so as is the case in the cockpit, we also go off the light on the FEP/GPU panel to confirm power is being delivered.

Diesel GPUs do make a sound of course when they are cranked up, but even when connected properly and when you can hear the GPU's diesel engine sound chugging away, this is still no guarantee that the power will be available, since there are two generator settings for most GPUs, and you have to have the right one selected for it to work: When you start a GPU up, it will be in 'idle' mode and will not be delivering power even if the cable is connected to the aeroplane; what you have to do is flip a toggle switch on its control panel to select 'excite', and then press a power button to commence electrical power delivery. That last button will usually illuminate to confirm it is delivering power.

When you hit the excite button on a GPU, the diesel revs will change and you can hear that when outside of course, but if you walked up to a GPU without hearing that engine note change, it would be difficult to tell whether it was in idle or excite mode as the rev change isn't massive and either way, unless you had the cockpit window open, you'd probably not hear the GPU anyway. This is why we normally knock on the fuselage to give the crew a heads up and then having caught their attention, we give the hand signal to let them know they have power connected, just in case their overhead indicator light is U/S. For those of you who like all that GSX malarkey, the hand signal for indicating that ground power is connected, is sort of similar to the 'time out' signal used by referees in sports matches, i.e. your clenched fist punching your other hand's palm to mimic the 'plugging in' movement, and the reverse of this movement is used to enquire if it is okay to unplug.

Chances are you'd have a hard time hearing a diesel GPU when in a Falcon, since unlike with most big airliners, where the GPU is usually positioned near the connector near the nose gear (so right next to the cockpit), on a Falcon 50, the GPU/FEP plug connects to a socket near the tail of the aeroplane, so it's quite a way from the cockpit and on a noisy ramp its sound would be lost among all the other noise.

Edited by Chock

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5 hours ago, FDEdev said:

IRL, on most airports the GPU is directly connected to the airbridge or any other fixed ground equipment so you don't get any aural or visual feedback.

Furthermore I've seen a lot old 'real' GPUs which do make a lot of noise, but don't deliver any, or the correct power.

The only reliable source is the cockpit indication!

Some aircraft have a light on the flight deck to show when the GPU is connected, but the Falcon does not.

If the main voltmeters show 28 volts, external power is supplying the systems. If they show only 24 volts, the aircraft is running on battery power.

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I was just simply saying for sim immersion it might be pretty neat to have some sort of indication other than just the volt meters. And in real life yes..the Hobart GPU 400's and 600's which ive used many many times do in fact make an electrical discharge hum thats very audiable outside the aircraft..along with cooling fans ect..they are not silent at all. This seems to be the gpu that is modeled. Now technically no, you cant hear it in the cockpit..in a small CJ with the door open maybe but not very much at all. Certainly not in a falcon...i do see your point, sometimes for me though..things that lend to immersion arent necessarily accurate in real life..but are pretty immersive on a computer screen lol.

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Here is what a large GPU sounds like that might be used to power a Falcon 50?

 

 

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Next version will need the battery on for the APU to work.

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6 hours ago, MartinRex007 said:

Here is what a large GPU sounds like that might be used to power a Falcon 50?

 

 

It certainly could be, though that particular GPU is probably bigger than what a Falcon would actually require.

It’s probably a dual-voltage GPU that can produce 28 Volts DC for biz jets like the Falcon, and 115 Volt 3-Phase AC for larger aircraft with AC electrical systems.

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Mark, don't worry about sourcing GPU sounds.  First, your model is of a FoxCart-style GPU (battery/wall plug) so it doesn't make any diesel sound.  However, if you want to add a GPU, just let me know.  I'll send you a package of pics of our JetGo here at work and a recording of its entire start, rev to operating RPM, slow to idle, cooldown, and shutdown cycle on a quiet ramp so it'll be well isolated.  Just hit me up here or on Facebook.  I will probably get these pics and recording in the next week or so because it's been a sticking point on several add-ons that I've wanted to submit for approval.

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