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Author Topic: Weight of charge  (Read 326 times)
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billdennis747
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« on: March 15, 2020, 12:09:54 PM »

To save me driving 14 miles to replace my cylinder, does anyone know the weight of charge for a standard Telco tank? Dan?
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Jack Plane
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« Reply #1 on: March 15, 2020, 01:11:10 PM »

Don't know the exact fig for a Telco, but the full liquid charge of the similar sized tank on my GM 63 BB is about 1.2g
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DHnut
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« Reply #2 on: March 15, 2020, 01:30:41 PM »

Bill,
      A figure of 3 gm for a liquid charge is what I have seen somewhere.
Ricky
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billdennis747
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« Reply #3 on: March 15, 2020, 01:58:29 PM »

Thanks both. I was pondering the likely outcome of sticking a Telco in this with the tank maybe at the LE
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Pete Fardell
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« Reply #4 on: March 15, 2020, 02:39:32 PM »

Thanks both. I was pondering the likely outcome of sticking a Telco in this with the tank maybe at the LE
F.b.12? Very interesting, and a nice change from DH2s.
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danmellor
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« Reply #5 on: March 17, 2020, 11:58:19 AM »

Sorry Bill, I've never been technically minded enough to weigh the charge. Another approach would be to plumb a bigger tank in; lay it flat right in the nose and fly on gas charge only.

Nice choice!

Dan.

P.S You could always scale it for the Modela!
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g_kandylakis
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« Reply #6 on: March 22, 2020, 05:51:23 PM »

15,8 gr empty weight

17,5 gr with liquid charge

1,7 gr for the charge. Second charge immediately after running so with a cool tank. Seems little, I know, but that is what I got, from a new sodastream cylinder.

45 seconds on a realistic power setting, 67 total running time.

hope it helps a bit
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USch
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« Reply #7 on: March 22, 2020, 06:46:24 PM »

Sorry for not having written before  Angry
A quick look at Wikipedia reveals that liquid CO2 has a density of 1,101 kg/m3.
In other words 1cm3 weighs 1,101g. Calculate the volume of your tank and multiply by 1,1 gives you the weight of a full, liquid charge. Most tanks have either 2, 3, 5 or 10 cm3.

Urs
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g_kandylakis
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« Reply #8 on: March 22, 2020, 06:54:39 PM »

Hi Urs,

I am afraid it is not that easy...

The tank never gets full with liquid. As soon as liquid flows in, some of it evaporates. The warmer the tank the more gas fills it. That is why the experts in F1K cool their tanks with greezer sprays, to reduce gas evaporation inside

George
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billdennis747
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« Reply #9 on: March 23, 2020, 03:30:31 AM »

Many thanks George et al. I think with the tank near the LE I can cope with that. It may even be an advantage to have the CG a couple of mm forward at the beginning of the flight
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USch
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« Reply #10 on: March 23, 2020, 07:42:07 AM »

Your right, George!

But experts also weight tank and motor at the end of the charge, because even them dont know exactly how much gas goes into it. That would also mean that Bill's question cannot be answered exactly.

But as I understood, Bill wanted a practical answer, not down to  the last 0,01g. And saying your tank has a volume of 3cm3, so consider about 3g of charge is sort of practical answer.

Have a good time even in lock-down times  Sad Sad Sad
Lot's of time to build models   Grin Grin Grin

Urs
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