engineers GPU missing start run switch

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alan CXA651
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engineers GPU missing start run switch

Post alan CXA651 »

Hi
During a conversation while trying to help a new connie pilot , some of us realised that the GPU is missing its start/run switch on the engineers panel , the manual is also missing this switch , but the introductory video , clearly shows this switch , when was it removed , and what was the reason for its removal , as the only way to turn it on/off is via the shift+3 popup at this time.
EDIT
Manual page100 shows switch page 119 switch missing
introductory video 2:31 into vid switch shown 2:41 into vid its missing
regards alan. 8)
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Hook
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Re: engineers GPU missing start run switch

Post Hook »

I thought it was obvious. The old switch was for an APU which is installed in the aircraft. This requires a start and run switch. The new GPU is a ground power unit that the ground crew plugs in. They have their own switch at the connection to the aircraft.

I'm interested in the official A2A explanation though.

Hook

alan CXA651
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Re: engineers GPU missing start run switch

Post alan CXA651 »

Hi Hook.
As an ex avionic aircraft engineer in the RAF 9 years and worked for BAe and BA on modern jets , All the GPUs where plugged in by ground crew and fired up , but the power from them was ALWAYS turned on and of in the flight deck by either ground crew servicing the aircraft or the flight crew , there was never a switch down by the aircraft power connector , it was done that way as a safty factor .
If A2A left it off on the connie , then i would say its because they are on the poly and performance limit , but not 100% sure on that , hence why i asked.
regards alan. 8)
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CAPFlyer
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Re: engineers GPU missing start run switch

Post CAPFlyer »

Alan, yes modern jets have it, however that wasn't always the case. Even some modern pistons don't have a GPU switch. Every Cessna single I've ever flown and most of the piston twins that I've seen don't have one, even though they have a GPU plug. I think the difference is that the assumption is that the battery switch is the control here. If the battery switch is off, then nothing is powered. When you turn on the battery, everything is powered. I believe these aircraft also have a voltage regulator and/or disconnect (breaker for lack of a better term) in the circuit as well that will open if the voltage is not within the required range, something that most modern jets have as well even though they have the switch as well.
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alan CXA651
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Re: engineers GPU missing start run switch

Post alan CXA651 »

Hi Capflyer.
I have work on the britannias in the RAF they had batt an two ground power on/off switches in the flight deck , you cannot compare GA with commercial airliners regards power points .
Also look at the manual pages as indicated on first post and introductory video at times stated to see what i am querying also on video at 0:41 it looks like a switch and light on the GPU panel on the real 041 .
regards alan. 8)
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Hook
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Re: engineers GPU missing start run switch

Post Hook »

Didn't someone post a pic of a real Connie that didn't have the switch?

Hook

maddz
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Re: engineers GPU missing start run switch

Post maddz »

Yes in the radio thread page 4.

It’s a fuse, screw top type next to the orange Lamp.

Good eye 👁 spotting that in the manual

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CAPFlyer
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Re: engineers GPU missing start run switch

Post CAPFlyer »

Here's a picture of the QANTAS Connie at the QFM in Australia. Switches for batteries, light only for GPU.

https://qfom.com.au/wp-content/uploads/ ... neer-1.jpg

I'm pretty sure the B-29 also has no Ground Power switch in the cockpit. That is because the switch is back in the tail with the APU (putt-putt) that closes the circuit for either the GPU or APU, whichever is connected. Up front there is only a switch for the Putt-Putt ignition and that it's on. The actual "contactor" is back in the back.

https://sites.rootsweb.com/%7Eny330bg/I ... tt5big.jpg

I'm not saying your wrong Alan, just saying there are aircraft out there that don't have a GPU switch in the cockpit.

Also, it's entirely possible that they just use a circuit breaker that we don't see (in the real plane) to accomplish what the switch would. So much of how things were put in and done was changed later in the 1970s when the planes passed into 2nd and 3rd line service. And not everything that was done then was exactly "by the book" and figuring out which was and wasn't isn't that easy.

Also, I did find that back when these planes were first built, there were at least 2 other methods of switching for GPU/External Power. Boeing used a separate GPU switch while Douglas and Convair used a 2-position switch (External or Battery). It seems the Military preferred the 2-position switch as I found that on a couple fighters as well when they did have them. The Lockheed P-38 doesn't have a switch, but I'm not sure that it had an external power jack either.
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Hook
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Re: engineers GPU missing start run switch

Post Hook »

I always figured a pic of the real aircraft always trumped any theoretical knowledge. :D

I think part of the real explanation is that A2A models a specific aircraft or a typical installation, not every aircraft of that model in existence. This is what we've been told in the past.

Hook

alan CXA651
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Re: engineers GPU missing start run switch

Post alan CXA651 »

Hi Capflyer.
That picture you give the link for , appears to be from a L1049 , if you look carfully and i needed a magnifier to look at it , the two switches L to R are marked ship and cart batt , and is a different layout to the L049 that scott showed in the intro video.
Some aircraft had a warning light to say GPU was plugged in and power turned on at the GPU , but the switch or switches to turn it on in the cockpit so aircraft used the avil power , was not always in same place , it all depended on the operators as to where they where placed with individual airline mods , that the aircraft manufactor would fit on request , what i saw on the intro video of the L049 connie that i assume a2a based thier connie on , and you need to freeze the video between 030 -042 into the video , you can see the light and what looks like a switch in a centre position , you might need a magnifier to see it , as its almost hidden by the light .
I was also querying the manual page 100 and 119 that shows a switch there then its not there , which is confusing , and intro video shows it there then not there again confusing at 2:31 and 2:41 into the video.
regards alan. 8)
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CAPFlyer
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Re: engineers GPU missing start run switch

Post CAPFlyer »

Ref. the manual - the pic on page 100 shows the B377 APU control installed in the panel, including being labelled "APU Control Panel". On that switch, up is run, down is start, and the middle is just neutral.

As for the Super Connie pic, you're right. I didn't see that it said "Cart Batt" on the right switch. I was just trying to illustrate similar setups, not say that's how the L-049 should be anyway.
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trisho0
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Re: engineers GPU missing start run switch

Post trisho0 »

GPU start run switch is missing from the Engineer Control panel inside the Connie? If it is supposed to be no switch installed what about the switch I found from: https://imgur.com/LSFbuLR

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CAPFlyer
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Re: engineers GPU missing start run switch

Post CAPFlyer »

That was an in-development screen when they had simply installed the B-377 GPU gauge/system during testing before making the decision to go with the GPU route.
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trisho0
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Re: engineers GPU missing start run switch

Post trisho0 »

So, there is no GPU start run switch in the FE panel in real, correct?

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Gypsy Baron
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Re: engineers GPU missing start run switch

Post Gypsy Baron »

You toggle the GPU on/off using the 'Controls' menu. Shift+3

Paul

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