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Author
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Topic: Gemini spacecraft: Fuel cells vs batteries
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Jim_Voce
Member Posts: 273
From:
Registered: Jul 2016
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posted 07-22-2016 02:37 AM
   
The Gemini III and IV spacecraft used batteries for internal power and Gemini V was the first spacecraft to use fuel cells. Does anyone know what the weight difference was between fuel cells and batteries? And on Gemini V, was there any practical possibility of it using batteries for its eight day mission? |
schnappsicle
Member Posts: 396
From: Houston, TX, USA
Registered: Jan 2012
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posted 07-22-2016 07:01 AM
I'm not sure how much the batteries weighed, but I remember reading somewhere that the batteries were designed to have a usable lifespan of four days. I believe that making larger eight day batteries would definitely make them too heavy. As you probably know already, it wasn't just the weight of the batteries that was a concern. If they didn't use fuel cells, they'd have to take along eight days worth of drinking water for two men, which would also add considerable weight to the spacecraft.This brings up another good question. Were the batteries used in the Lunar Module the same type that were used in Gemini? For that matter, were they the same used on Mercury? I know the LM batteries only had a four day lifespan. Were they thinking that far ahead, or did they plan on using the Gemini batteries in the LM from the moment the LM was first conceived? |
SpaceAholic
Member Posts: 4494
From: Sierra Vista, Arizona
Registered: Nov 1999
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posted 07-22-2016 07:05 AM
GT-5 leveraged fuel cells with supplementation from batteries. |
schnappsicle
Member Posts: 396
From: Houston, TX, USA
Registered: Jan 2012
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posted 07-22-2016 07:16 AM
Was that because the fuel cells were stored in the Equipment Module which was jettisoned prior to reentry? |
schnappsicle
Member Posts: 396
From: Houston, TX, USA
Registered: Jan 2012
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posted 07-22-2016 07:21 AM
quote:
Originally posted by Jim_Voce:
Does anyone know what the weight difference was between fuel cells and batteries?
I found this on Geminiguide.com: The four main batteries are 45 ampere/hour, 16 cell, silver-zinc batteries. The three squib batteries are 15 ampere/hour, 16 cell, silver-zinc batteries. The squib batteries are special high-discharge-rate batteries which will maintain a terminal voltage of 18 volts for one second under a 75 ampere load.The main and squib battery cases are made of titanium. The approximate activated (wet) weight for each squib battery is 8 lbs and each main battery 17 lbs. The adapter module battery cases (spacecraft 6) are constructed of magnesium and the approximate wet weight of each battery is 118 lbs. I could not find the weight of the fuel cells on that page. |
micropooz
Member Posts: 1532
From: Washington, DC, USA
Registered: Apr 2003
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posted 07-22-2016 11:08 AM
Gemini 6 used just batteries as well. |
Jim Behling
Member Posts: 1488
From: Cape Canaveral, FL
Registered: Mar 2010
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posted 07-22-2016 02:04 PM
quote:
Originally posted by schnappsicle:
Were the batteries used in the Lunar Module the same type that were used in Gemini? For that matter, were they the same used on Mercury?
What do you mean by same type? Silver Zinc? Then yes. Same model, then no. The spacecraft were built by different contractors and had different requirements. NASA would not have gone into the detail of which batteries to specify. That would be up to the contractors. quote:
Was that because the fuel cells were stored in the Equipment Module which was jettisoned prior to reentry?
That is also where the main batteries were also mounted. The reentry module had to have separate batteries regardless of type of main power source since had to operate without the EM for a short while. |
schnappsicle
Member Posts: 396
From: Houston, TX, USA
Registered: Jan 2012
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posted 07-25-2016 07:25 AM
If the batteries were housed in the Equipment Module, what did they use for power during reentry? My point was that they had to have some batteries to power the cockpit during reentry.Having the same batteries for Gemini and Apollo is not as far fetched as you make it appear. First of all, neither Grumman, or NAA made their own batteries. They had to buy them from somewhere. Of course NASA didn't specify components, but wouldn't the contractors benefit with lower costs and speed up the fabrication process by using a proven and tested component instead of redesigning a new one from scratch? |
Jim Behling
Member Posts: 1488
From: Cape Canaveral, FL
Registered: Mar 2010
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posted 07-25-2016 08:11 AM
quote:
Originally posted by schnappsicle:
If the batteries were housed in the Equipment Module, what did they use for power during reentry?
I said it in my last post "The reentry module had to have separate batteries." quote:
Having the same batteries for Gemini and Apollo is not as far fetched as you make it appear.
Very far fetched. They were different vehicles which had different requirements which drove different shape factors, different loads, different environments, different outputs, etcAnd there are other reasons. When a supplier builds a specific design for a customer, they usually have to get permission from that customer to able to sell it to others. NAA and GAC would be designing their spacecraft and coming up with electrical requirements. They would take these requirements and farm them out to potential suppliers. The suppliers would respond with their proposal to meet the requirement. If they had something existing that was close to same fit, form and function, they would likely negotiate to use it. But back in those days, there was no off the shelf products and catalogs that spacecraft builders could use in their designs. It wasn't like being able to build your own PC like you can today. |
SpaceAholic
Member Posts: 4494
From: Sierra Vista, Arizona
Registered: Nov 1999
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posted 07-25-2016 08:32 AM
And of course different prime contractors.  |
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