Re: 500 mile flight?
Ralph Wallio, W0RPK <wallio@...>
The discussion of Mean Zonal Winds (MZW) attoggle quoted messageShow quoted text
http://users.crosspaths.net/~wallio/MZW.html helps us start planning toward
a long distance mission (but lets plan toward more than 703.02 miles to give
us a chance at breaking the SSOK/WB0DRL record - see
http://users.crosspaths.net/wallio/RECORDS.html). MZW data includes mean
wind speed (m/s) at various altitudes but there is no directional component
other than westerly vs. easterly.
Referring to the data table for 40dN latitude and looking at winds between
60k and 80kft, we can see that December-January would be best for a west to
east flight. MZW velocity varies 10-18m/s (20-35kts) depending on altitude.
Based on these mean values and an average of 27.5kts (31.6mph), it would
take 704/31.6 = a little over 22-hours aloft to break the record.
Taking this MZW estimate up to 24-hours and 760 miles, the mission could be
launched late in the afternoon from the Denver area and recovered before
nightfall the following day. Touchdown would be somewhere on an arc running
through western Wisconsin, western and central Illinois and eastern Missouri
from Duluth, MN to Little Rock, AR. This is as close as we can predict this
far out but there would be significantly more precision during the final
days of preparations.
Winds aloft at lower altitudes are highly variable in both speed and
direction (hot air balloon distance record breaking attempts often wait
months, even years, for the right conditions, 10k-18kft) but they are
somewhat dependable within a season at higher altitudes. I say "somewhat
dependable" because our collective flight experience shows significant
variations in characteristics for flights in the same month (see MZW
discussion). EOSS-46 experienced easterlies above 60kft in January which
are totally unpredicted by MZW data while EOSS-53 in December matches the
MZW prediction almost perfectly.
Launching in the late afternoon would minimize helium loss from the
zero-pressure envelope due to solar heating during the early hours of the
mission. After sunrise solar heating would provide more lift helping keep
the balloon and payload above 60kft and controlled airspace until flight
termination. Precision track predictions in the last few days before flight
would allow the recovery crew to position themselves appropriately,
southeastern Missouri to west central Wisconsin.
TNX es 73 de Ralph Wallio, W0RPK
Component cost is not the same thing as system cost
----- Original Message -----
From: K. Mark Caviezel <email@example.com>
Sent: Thursday, May 16, 2002 11:39 AM
Subject: [GPSL] 500 mile flight?