Return-Path: Received: (qmail 2073 invoked from network); 15 Mar 2000 00:12:01 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by teachers.core.plus.net.uk with SMTP; 15 Mar 2000 00:12:01 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.02 #1) id 12V1K4-0003b5-00 for rsgb_lf_group-outgoing@blacksheep.org; Wed, 15 Mar 2000 00:06:00 +0000 Received: from [194.73.73.138] (helo=ruthenium) by post.thorcom.com with esmtp (Exim 3.02 #1) id 12V1K2-0003b0-00 for rsgb_lf_group@blacksheep.org; Wed, 15 Mar 2000 00:05:58 +0000 Received: from [213.1.178.2] (helo=default) by ruthenium with smtp (Exim 2.05 #1) id 12V1M6-0004qF-00 for rsgb_lf_group@blacksheep.org; Wed, 15 Mar 2000 00:08:07 +0000 Message-ID: <000301bf8e11$5be9cb20$02b201d5@default> From: "Alan Melia" To: "rsgb_lf_group" Subject: LF: Balloon flying Date: Tue, 14 Mar 2000 23:58:48 -0000 MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 4.72.3110.5 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Hi All, as a result of the donation of some old mags I came across the following table in an article in 73 mag (April 1972 ), which may be of interest to those without a tower contemplating a BIG vertical. The table relates to lift generated by a helium filled balloon at different gas temperatures. Balloon Gas vol lift (lb) lift (lb) diam. ft cu.ft. @0degC @20degC 2 4 0.25 0.25 3 14 1 0.75 4 33 2 2 5 65 4 4 6 113 7 7 7 180 12 11 8 268 18 17 9 381 26 24 10 523 36 33 11 696 48 44 12 904 62 58 Sorry to our metric friends (1ft=0.3m and 1lb=0.45kgm or there abouts) I think metres are unknown the other side of the pond. They even measure the size of the engine bay in cubic inches (It IS the engine bay isn't it?) It goes on up to 16 feet diameter but I reckon if you have got a big enough garden to blow up a 16 foot diameter ballon you have enough room for tower! He mentions flying a 160foot vertical with an 8foot weather balloon inflated to 3.5 feet diameter. (He ran out of gas). He also relates burning out a 30AWG aerial wire with about 180 watts on 80m. Though I must admit I have no idea how he derives an impedance of feed 50ohms for the end of a halfwave! That shouldn't bother us as, at least I, will be quite happy with a quarter wave on 136! Cheers de Alan G3NYK Alan.Melia@btinternet.com