| |
DK2ZA > INFO 20.07.02 22:53l 47 Lines 1310 Bytes #999 (30) @ WW
BID : K7CDB0MRW0AF
Read: DB0FHN GUEST
Subj: re: balloons (G0TEZ)
Path: DB0FHN<DB0ZWI<DB0HOT<DB0MRW
Sent: 020720/2334z @:DB0MRW.#BAY.DEU.EU [Wunsiedel, JO60AB] Bcm1.46 LT:030
From: DK2ZA @ DB0MRW.#BAY.DEU.EU (Helmut)
To: INFO @ WW
X-Info: Sent with login password
There is a subtle but significant error in Ian's (G0TEZ) statement:
>> Helium is twice the density of Hydrogen so there is only
>> half the lifting force ..
The densities of air, helium and hydrogen at 1.0132 bar and 0 DEG Celsius
are 1.293, 0.178 and 0.09 kilograms/cubic meter.
The weights of one cubic meter of these gases are
air: 1.293 * 9.8 N = 12.67 N (N = Newton)
helium: 0.178 * 9.8 N = 1.74 N
hydrogen: 0.09 * 9.8 N = 0.88 N
The lifting force of a balloon of one cubic meter "filled" with
vacuum would be
weight of displaced air - weight of balloon =
= 12.67 N - weight of balloon
If this balloon is then filled with helium the lifting force becomes
12.67 N - 1.74 N - weight of balloon =
= 10.93 N - weight of balloon
Or if it is filled with hydrogen the lifting force becomes
12.67 N - 0.88 N - weight of balloon =
= 11.79 N - weight of balloon
The difference is 0.86 N. So the lifting force of a balloon filled
with helium is only slightly smaller than the lifting force of a
balloon filled with hydrogen.
vy 73 de Helmut, DK2ZA
Read previous mail | Read next mail
| |
