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#31
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Volocopter - safest aircraft in the world
Martin Gregorie wrote on 12/13/2015 7:26 AM:
Personal view: given than BRS landings seem to be quite hard, the thought of flying something to which the only way out of any type of emergency is "fire the BRS" is not reassuring. I think you do not have a good idea of "quite hard" - BRS systems in certified aircraft like the Cirrus and Phoenix are sized to land the aircraft slowly enough to avoid injury most of the time. I think with the Volocopter - we'll have to wait to see if their testing backs up their claim of "gently", but it certainly seems achievable, given the lower max speeds. I'm sure they have a number of ways to deal with the "dead zone" as you obviously need the aircraft to be moving through the air for a parachute to work. I'm guessing it would not be allowed to deploy when hovering (and you don't need it then, either), perhaps by automatic means. -- Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me) - "A Guide to Self-Launching Sailplane Operation" https://sites.google.com/site/motorg...ad-the-guide-1 - "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm http://soaringsafety.org/prevention/...anes-2014A.pdf |
#32
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Volocopter - safest aircraft in the world
Thanks to all of you, supporting what I wrote before and clarified some of the special "chopper-questions". Looks like my english actually is worse than I thought it would be, so not everybody seem to understand what I try to say.
Anyway, who ever has visited the website of e-volo, he should have found at first page the title "Safety first". Clicking at that link, you get a nice picture of the activation-handle for the BRS, as well as a brief description when to use it. http://www.volocopter.com/index.php/en/safe-en At this link on YouTube, you get a video showing the first test-shootout of the system. https://www.youtube.com/watch?v=lffpmcuuOPE And yes, the chute did NOT deploy at this situation, as the craft is static at the ground, no horizontal nor vertical speed, so no air to do the job inflating the chute of course. In reality, I could only think about two situations, when a helicopter has no vertical or horizontal speed: 1.) the pilot hovers the craft safely somewhere above the ground in any hight, sure no vertical and no horizontal speed and of course no need to activate thes BRS. 2.) pilot is not hovering safely in the air and again no horizontal nor any vertical speed - pilot missed the right moment to activate the BRS ...... After all, the VC200 you see at the e-volo website is just the prototype as stated in my article. It has not been operated with occupants in the cockpit but with adequate ballast. As its preliminary permission by Federal Administration (LBA) allows remote controlled and unmanned test-flights only, until its safe operation is finally proofed and the test-program is completed. After that, they sure get full test-permission by the Authority to be operated with occupants on board the craft. IŽll follow up the further progress of development and report any news at my website (http://ul-segelflug.de/blog.html), so please feel free to visit my site at any time. Best regards from Germany, wishing you all and your family-members a nice Christmas-time and a happy, safe and healthy 2016. Klaus |
#33
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Volocopter - safest aircraft in the world
On Sun, 13 Dec 2015 17:36:50 -0800, Eric Greenwell wrote:
Martin Gregorie wrote on 12/13/2015 7:26 AM: Personal view: given than BRS landings seem to be quite hard, the thought of flying something to which the only way out of any type of emergency is "fire the BRS" is not reassuring. I think you do not have a good idea of "quite hard" - BRS systems in certified aircraft like the Cirrus and Phoenix are sized to land the aircraft slowly enough to avoid injury most of the time. IIRC the reports of the first few SR22 BRS recoveries talked about broken undercarriages and I'm certain I've seen a photo of a BRS-recovered glider with a smashed nose. Both fit my definition of 'quite hard'. I think with the Volocopter - we'll have to wait to see if their testing backs up their claim of "gently", but it certainly seems achievable, given the lower max speeds. I'm sure they have a number of ways to deal with the "dead zone" as you obviously need the aircraft to be moving through the air for a parachute to work. I'm guessing it would not be allowed to deploy when hovering (and you don't need it then, either), perhaps by automatic means. A situation that would leave it in the dead zone would be if the pilot is pushing it on battery capacity because he is determined to make his declared airfield despite a stronger than predicted head wind, the battery hits zero at less than safe BRS deployment height on approach. -- martin@ | Martin Gregorie gregorie. | Essex, UK org | |
#34
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Volocopter - safest aircraft in the world
On Mon, 14 Dec 2015 00:43:19 -0800, Kilo-Bravo wrote:
At this link on YouTube, you get a video showing the first test-shootout of the system. https://www.youtube.com/watch?v=lffpmcuuOPE And yes, the chute did NOT deploy at this situation, as the craft is static at the ground, no horizontal nor vertical speed, so no air to do the job inflating the chute of course. In reality, I could only think about two situations, when a helicopter has no vertical or horizontal speed: Interesting video. Thanks for posting it. BTW, from the BRS website "The altitude required is a function of speed more than height. FAA certified tests have shown that full parachute inflation could occur as low as 260-290 feet above the ground." That's 80-90m, but implies that you'd need to be rather higher if flying slowly or hovering. Bruce's figures for the R22 autorotation recovery (400ft/125m hovering, 200ft/62m at 55 kts) indicate that a BRS system would need 150% more height than an R22 for a safe BRS recovery. 1.) the pilot hovers the craft safely somewhere above the ground in any hight, sure no vertical and no horizontal speed and of course no need to activate thes BRS. 2.) pilot is not hovering safely in the air and again no horizontal nor any vertical speed - pilot missed the right moment to activate the BRS ..... Murphy says that something will go wrong at some time & place in both these situations. After all, the VC200 you see at the e-volo website is just the prototype as stated in my article. It has not been operated with occupants in the cockpit but with adequate ballast. As its preliminary permission by Federal Administration (LBA) allows remote controlled and unmanned test-flights only, until its safe operation is finally proofed and the test-program is completed. After that, they sure get full test-permission by the Authority to be operated with occupants on board the craft. Understood. It will be interesting to see what pilot certification the LBA decide is needed to fly one. -- martin@ | Martin Gregorie gregorie. | Essex, UK org | |
#35
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Volocopter - safest aircraft in the world
On Monday, December 14, 2015 at 4:18:52 PM UTC+3, Martin Gregorie wrote:
That's 80-90m, but implies that you'd need to be rather higher if flying slowly or hovering. Bruce's figures for the R22 autorotation recovery (400ft/125m hovering, 200ft/62m at 55 kts) indicate that a BRS system would need 150% more height than an R22 for a safe BRS recovery. Just to amplify: 200 ft is always the corner for the R22. 55 knots is the critical speed at max AUW, worst CG and about 3000 ft density altitude. At sea level 53 knots is ok at any altitude, and at 7000 ft you need about 58 knots. |
#36
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Volocopter - safest aircraft in the world
On Mon, 14 Dec 2015 06:05:33 -0800, Bruce Hoult wrote:
On Monday, December 14, 2015 at 4:18:52 PM UTC+3, Martin Gregorie wrote: That's 80-90m, but implies that you'd need to be rather higher if flying slowly or hovering. Bruce's figures for the R22 autorotation recovery (400ft/125m hovering, 200ft/62m at 55 kts) indicate that a BRS system would need 150% more height than an R22 for a safe BRS recovery. Just to amplify: 200 ft is always the corner for the R22. 55 knots is the critical speed at max AUW, worst CG and about 3000 ft density altitude. At sea level 53 knots is ok at any altitude, and at 7000 ft you need about 58 knots. Understood. I was comparing that 200 ft with the BRS site's quoted 'might get away with popping it at 260-280ft', this presumably including both height for the chute to inflate (minimal at speed since the aircraft pitches up on deployment) followed by the height used up waiting for the plane to be swinging gently enough for the crew to survive meeting the ground. -- martin@ | Martin Gregorie gregorie. | Essex, UK org | |
#37
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Volocopter - safest aircraft in the world
Martin Gregorie wrote on 12/14/2015 5:16 AM:
That's 80-90m, but implies that you'd need to be rather higher if flying slowly or hovering. Bruce's figures for the R22 autorotation recovery (400ft/125m hovering, 200ft/62m at 55 kts) indicate that a BRS system would need 150% more height than an R22 for a safe BRS recovery. You are assuming the R22 rotor system is intact and functioning correctly. If the R22 has a failure in the rotor system, I think it's "gave over", while the Volocopter could deploy it's BRS even with multiple rotor or motor failures as long as it's high enough. Sure, there would be a dead zone of a few hundred feet, but the BRS would work from there up to it's ceiling. -- Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me) - "A Guide to Self-Launching Sailplane Operation" https://sites.google.com/site/motorg...ad-the-guide-1 - "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm http://soaringsafety.org/prevention/...anes-2014A.pdf |
#38
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Volocopter - safest aircraft in the world
Martin Gregorie wrote on 12/14/2015 4:49 AM:
A situation that would leave it in the dead zone would be if the pilot is pushing it on battery capacity because he is determined to make his declared airfield despite a stronger than predicted head wind, the battery hits zero at less than safe BRS deployment height on approach. We are in agreement that you are in trouble if your thrust stops below a certain altitude; it doesn't matter how you get there - running your battery or fuel tank to empty is going to ruin your day. -- Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me) - "A Guide to Self-Launching Sailplane Operation" https://sites.google.com/site/motorg...ad-the-guide-1 - "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm http://soaringsafety.org/prevention/...anes-2014A.pdf |
#39
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Volocopter - safest aircraft in the world
Eric Greenwell wrote on 12/14/2015 7:16 PM:
I think it's "gave over", That should be "game over"! -- Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me) - "A Guide to Self-Launching Sailplane Operation" https://sites.google.com/site/motorg...ad-the-guide-1 - "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm http://soaringsafety.org/prevention/...anes-2014A.pdf |
#40
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Volocopter - safest aircraft in the world
On Mon, 14 Dec 2015 19:35:53 -0800, Eric Greenwell wrote:
Eric Greenwell wrote on 12/14/2015 7:16 PM: I think it's "gave over", That should be "game over"! Correct! As for the rest, please bear in mind that is wasn't looking at catastrophic structural failure where, of course, you're correct. OTOH I was on about the situation where the only way out from *any* failure in a Volocopter is to pop the BRS and pointing out that this is fatal if it happens down in the death zone at a height from where a conventional aircraft could usually glide or autorotate to a landing. -- martin@ | Martin Gregorie gregorie. | Essex, UK org | |
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