Start 1 & Start 2: why 2 possibilities instead of one?
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<p>I’d like to know the precise reason why there are 2 possibilities to Start the engine : I understand that one uses an accumulator while the second uses the whole, but what is the deep interest of having these 2 possibilities ?<br />indeed, if START2 allows each time to start the engine efficiently, then why use START1?</p>
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<p>In the beginning of the life of the falcon, the thought was if start 1 failed, then you had a second attempt readily available. The issue became that start 1 failed 60% of the time. a study was done at Hill AFB and found that start 2 (uses both Hydraulic accumulators to turn the hydraulic start motor) then start failures dropped to about 20%, The weak link became the JFS Controller, which is another story for another day. Hope this helped.</p>
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<p>As had been told by <strong> </strong><a href=“https://forum.falcon-bms.com/user/gwes25” target=“_blank”><strong>gwes25</strong></a><strong> </strong> <br /><br />At the beggining, with cold temperature, was recomended use START 2 and hot temperature, START 1, but the theorical and the practical result was nos as expected, then… always use START 2</p>
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<p>( @Revientor What the hell brought you back for that? Getting ready for launch? :P)<br /></p>
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<blockquote>( @Revientor What the hell brought you back for that? Getting ready for launch? :P)<br /><br /></blockquote><p>HAHAHA, I never left bms, only the public forum (due the excessive amount of post in the past), I had been checking again the forum a few months ago… as you know in 3 or 4 weeks…</p>
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<p>@Revientor , Yes temps were a factor, I have seen failed start1 on perfect weather day and second flight of day. The system was so unreliable. We had numerous grd aborts for that reason. Have had my share of hand pumping JFS/Brake Accumulators and can say it is no fun and quite the workout. It took three people to pump the required 400 strokes to get them back to full charge. We asked god support to put a Hydraulic Mule on the back of a truck and follow the starts so as if one failed we just hooked up the hoses and charged the system then reserved the reservoir, much faster. Got some funny looks from the pilots at first, but they grew to understand. The new digital controllers really fixed the failure rate. Just a little history from my experiences.</p>
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<blockquote>@Revientor , Yes temps were a factor, I have seen failed start1 on perfect weather day and second flight of day. The system was so unreliable. We had numerous grd aborts for that reason. Have had my share of hand pumping JFS/Brake Accumulators and can say it is no fun and quite the workout. It took three people to pump the required 400 strokes to get them back to full charge. We asked god support to put a Hydraulic Mule on the back of a truck and follow the starts so as if one failed we just hooked up the hoses and charged the system then reserved the reservoir, much faster. Got some funny looks from the pilots at first, but they grew to understand. The new digital controllers really fixed the failure rate. Just a little history from my experiences.</blockquote><p><br />Cool history!!!<br />I can say that in the F18 are 300 strokes <img src=“/plugins/nodebb-plugin-emoji/emoji/android/1f920.png?v=gcfd8gb1ch8” alt=“” class=“not-responsive emoji emoji-android emoji–face_with_cowboy_hat” /> </p>
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<blockquote>It took three people to pump the required 400 strokes…</blockquote><p><br />Three people…? I do that many strokes alone in front of pornhub.</p>
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<p>@Aragorn , Shorter strokes?!</p>
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<p>@gwes25 <em>Hee hee…</em><br /><br />Touché… <em>(er… no pun intended)</em></p>