Those prices are crazy. In much smaller quantities, I just got a 3500
psi standard size cylinder for $155, here in the US. The first quote
was ~$300 but I was able to talk them into giving me more favorable pricing.
-Bob
On 10/25/2016 08:33 PM, Brian Feeney wrote:
They in dictated they were paying US $1450 / 10,000 lites which is $145 / m3. Wow. I haven't bought helium in quite a while.
Anyone care to share what you're paying per m3 for these types of quantities, or more, in the US, Canada... or what you've been quoted.
Cheers
Brian Feeney
On Oct 25, 2016 9:19 PM, "Ben Brockert" <wikkit@xxxxxxxxx <mailto:wikkit@xxxxxxxxx>> wrote:
It says the LOX tank capacitive sensor can read down to 11 liters. The
three runs don't deplete the tank below 11 liters, so they're not
running it empty. So it does not say much about concerns of having the
top strata of the LOX in the tank becoming warmer and mixed with
nitrogen, i.e. "fluffy".
A run to empty with the nitrogen system vs. a run to empty with the
helium system would be helpful there.
It says that run 3 required 80 liters per minute of nitrogen gas to
keep the tank at constant pressure during the hold before firing. If
someone feels like doing the calculation of how that translates to
heating a mass of LOX, I'll owe them a beer. Bonus points for using an
equation of state more advanced than the ideal gas law.
Ben
On Tue, Oct 25, 2016 at 5:26 PM, Robert Watzlavick
<rocket@xxxxxxxxxxxxxx <mailto:rocket@xxxxxxxxxxxxxx>> wrote:
> It would have been interesting to see the same data with static
regulators
> (non DPR). Depending on the Cv, I would have suspected a lower
pressure
> during the test. Of course you could argue that is an advantage
of the DPR
> is that it can compensate for a wider range of flow rates.
>
> Regarding Test 3 and the the extra 11% needed - is that due to
the N2
> dissolving in the LOX or leaks? Since the thrust was
essentially what was
> expected given the lower tank pressure, that means the "fluffy"
LOX concerns
> are unwarranted. Do we know the tank geometry? Long/skinny or
short/fat?
>
> In any event, this shows you can save a lot of $$$ by using N2
on the test
> stand.
>
> -Bob
>
> On 10/25/2016 01:24 AM, Ben Brockert wrote:
>>
>> Hey, data.
>>
>> https://copenhagensuborbitals.com/helium-versus-nitrogen/
<https://copenhagensuborbitals.com/helium-versus-nitrogen/>
>>
>>
>>
>
>
