Differences

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--- guides:hydrogen_vs_helium_fro_hab [2018/02/26 14:16] – [Helium:] rocketboy
+++ guides:hydrogen_vs_helium_fro_hab [2018/02/26 14:41] (current) – [Helium:] rocketboy
@@ Line 1: / Line 1: @@
 ====== Hydrogen vs Helium as a lifting gas for HAB ======
+The following is written as information only. The following in no way constitutes any form of accurate legal advice. If you choose to use Hydrogen the onus is on you to research the implications and take appropriate safety measures both for yourself personally and the general public.
 ===== Hydrogen: =====
@@ Line 5: / Line 7: @@
   * **cons:** Highly Flammable, needs a registered business to acquire, extra precautions needed.
-==== Helium: ====
+===== Helium: =====
   * **pros:** Non flammable, available retail.
   * **cons:** limited natural resource.
@@ Line 13: / Line 15: @@
 === Difference in lift: ===
 Hydrogen has a density of about 0.0899Kg/cu m (at 1 atm 15C).
-Pure Helium has a density of 0.1786Kg/cu m however balloon grade helium is usually only 97% Helium – giving it a density of 0.2094Kg/cu m
+Pure Helium has a density of 0.1786Kg/cu m however balloon grade helium is usually only 97% Helium – giving it a density of 0.2094Kg/cu m.  Air has a density of 1.225Kg/cum – giving:
-Air has a density of 1.225Kg/cum – giving:
   * **97% Helium** a lift of about 1.01Kg/cu m
-  * **Hydrogen** a lift of about 1.13Kg/cu m – so about **12% better than Helium**.
+  * **Hydrogen** a lift of about 1.13Kg/cu m – so about **12% better**.
 === Altitude difference. ===
-In practice the difference between Helium and Hydrogen is much less in terms of altitude attained. For example a 1Kg payload on a HY-1000 balloon at 5m/sec ascent rate would typically achieve around 32.0Km (105,000ft) on 97%Helium and 33.1Km (108,000ft) on Hydrogen – so **only 3% better.**
+In practice the difference between Helium and Hydrogen is much less in terms of altitude attained. For example a 1Kg payload on a HY-1000 balloon at 5m/sec ascent rate would typically achieve around 32.0Km (105,000ft) on 97%Helium and 33.1Km (108,000ft) on Hydrogen – so only **3% better.**
 === Difference in price: ===
@@ Line 31: / Line 32: @@
 Both of the above are lightweight (25Kg) cylinders that can be easily maneuvered.  Hydrogen prices drop to about £6 per cubic (inc VAT) if you are prepared to have a 70Kg 9cu m cylinder (based on Air Products 200bar X47 – 30 days rental)
+Prices from early 2018
 === Hydrogen Flammability ===
 The most likely cause of ignition for HAB use is probably a static discharge between the filled balloon and personnel or structures.  During Operation Outward (WW2 launch of circa 100,000 hydrogen met balloons) there were several instances of the balloons catching fire due to static discharge between the balloons and filling tents.  In some cases personnel were badly burned (but no fatalities).
+Also see [[guides:hydrogen|Suggested Safety Considerations when Using Hydrogen for Balloon Launches]]