28 Mar 2024, 16:12 [ UTC - 5; DST ]
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Post subject: Re: Cirrus SF50 Posted: 26 May 2017, 14:46 |
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Joined: 08/30/08 Posts: 5607 Post Likes: +805 Location: KCMA
Aircraft: SR22
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Username Protected wrote: A JET with a CHUTE and a very comfortable interior - for less money.
Who thinks their wives and families, or husbands, or whoever, would choose the Meridian, given the choice between the two? Exactly. Not to mention quieter, smoother... and it's a JET. Burn a little more fuel but on the other hand no prop to maintain and overhaul. This isn't a Citation killer, it's a Meridian killer. love this photo
100% agreed
_________________ TRUE-COURSE AVIATION INSURANCE - CA License 0G87202 alejandro@true-course.com 805.727.4510
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Post subject: Re: Cirrus SF50 Posted: 26 May 2017, 14:56 |
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Joined: 08/30/08 Posts: 5607 Post Likes: +805 Location: KCMA
Aircraft: SR22
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Username Protected wrote: And no prop with beta to aid you in stopping on slick surfaces or when a brake fails. The #1 cause of accidents in light jets is runway overruns. Turboprops don't have that high a risk. There are tradeoffs with a turbojet vs. a turboprop. Touch down is about 75kts
_________________ TRUE-COURSE AVIATION INSURANCE - CA License 0G87202 alejandro@true-course.com 805.727.4510
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Post subject: Re: Cirrus SF50 Posted: 26 May 2017, 15:07 |
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Joined: 01/31/09 Posts: 5233 Post Likes: +3026 Location: Northern NJ
Aircraft: SR22;CJ2+;C510
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Username Protected wrote: And no prop with beta to aid you in stopping on slick surfaces or when a brake fails. The #1 cause of accidents in light jets is runway overruns. Turboprops don't have that high a risk. There are tradeoffs with a turbojet vs. a turboprop. Touch down is about 75kts
Want to bet that more then half of all SF50's will land at 10 kts or more above ref speed?
How many folks land their Bonanzas at over 80 kts because they like to firmer control feel at higher speeds?
You recite the book but unfortunately pilots don't fly by the book. Then they discover they have only one tool to slow down, the brakes and tire friction, unlike other aircraft that give the pilot multiple tools.
The #1 reason pilots fail turbojet type rides is inability to fly at proper approach and landing speeds.
_________________ Allen
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Post subject: Re: Cirrus SF50 Posted: 26 May 2017, 15:31 |
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Joined: 02/14/08 Posts: 3158 Post Likes: +2660 Location: KGBR
Aircraft: D50
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Well, you could pull the chute like a drag-racer!
It has only one way to slow down. This seems a fairly minor point. It's a JET with a CHUTE!
I think JC said it best, on some thread, some time: any plane with props is a clown plane - at least to your average passenger. I say that proudly as I swing two huge ones.
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Post subject: Re: Cirrus SF50 Posted: 26 May 2017, 15:34 |
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Joined: 04/26/13 Posts: 19762 Post Likes: +19430 Location: Columbus , IN (KBAK)
Aircraft: 1968 Baron D55
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Username Protected wrote: Want to bet that more then half of all SF50's will land at 10 kts or more above ref speed?
How many folks land their Bonanzas at over 80 kts because they like to firmer control feel at higher speeds?
You recite the book but unfortunately pilots don't fly by the book. Then they discover they have only one tool to slow down, the brakes and tire friction, unlike other aircraft that give the pilot multiple tools.
The #1 reason pilots fail turbojet type rides is inability to fly at proper approach and landing speeds. This is a piloting issue not an equipment issue and certainly not a jet issue. The same argument can be made for the SR22 not having anti-skid or a reversing prop. The SF50 V REF is reported as 85 knots. The SR22s is 79. If the SF50 is in danger of overrunning the runway so is the SR22 for the same reason, and it's not the lack of anti-skid or reverse thrust. You may argue that residual thrust from the jet engine is a factor, and I'll grant you that, but I would say that it is insignificant to the calculation, especially compared to approach speed, which is directly controllable by any pilot.
_________________ My last name rhymes with 'geese'.
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Post subject: Re: Cirrus SF50 Posted: 26 May 2017, 15:36 |
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Joined: 01/31/10 Posts: 13101 Post Likes: +6969
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Username Protected wrote: This is a piloting issue not an equipment issue and certainly not a jet issue. The same argument can be made for the SR22 not having anti-skid or a reversing prop. The SF50 VREF is reported as 85 knots. The SR22s is 79. If the SF50 is in danger of overrunning the runway so is the SR22 for the same reason, and it's not the lack of anti-skid or reverse thrust.
You may argue that residual thrust from the jet engine is a factor, and I'll grant you that, but I would say that it is insignificant to the calculation, especially compared to approach speed, which is directly controllable by any pilot. Weight is significantly higher. No drag from prop.
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Post subject: Re: Cirrus SF50 Posted: 26 May 2017, 16:00 |
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Joined: 04/26/13 Posts: 19762 Post Likes: +19430 Location: Columbus , IN (KBAK)
Aircraft: 1968 Baron D55
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Username Protected wrote: 300kt aircraft does not average 300kt for the entire distance. Figure about 260 kt average with climb speed, descent speed, and 250 kt below 10,000' speed limit.
2.7 hrs instead of 2.3 hrs. 80+68+48 = 195 trip fuel + 9 taxi fuel + 80 1 hour reserve fuel (use first hour fuel burn - assume you did a go around and are flying at low altitude with increased fuel burn) = 284 gallons = 1903 lbs
You have a 596 lbs cabin load for the trip. Allen I'll grant you all of that. My attempt was not written test level accuracy so much as a ball park comparison, but your point is valid. What we don't know with precision is the time and fuel to climb, or the time and fuel to descend, so while your 260 average may be correct, it may also be low, as it seems to me. What I saw in Tom's article was "...burning the predicted 64 gallons of Jet A an hour, we routinely saw more than 300 knots." My 68 gph number was deliberately high, and my 300 knot speed was set to the lower end of the scale. There is enough margin of error here to make up quite a bit of fuel. For example let's say I'm flying from my home base in Columbus Indiana to Titusville, FL to take the kids to see the Kennedy Space Center before hitting the beach. We aren't likely to be significantly restricted in the climb or the descent, so let's say the average speed here is actually 280 and the fuel flow is as reported (64 gph at cruise). The enroute time becomes 2.5 hours, the fuel required including your taxi and hour 1 reserve fuel burn rate becomes 80+64+32+9+80=1775.5. 2499-1775.5=723.5 which carries my family and 123.5 lbs of stuff. Close enough. You are right to point out that my first numbers may not be accurate. I don't think our pencil is sharp enough yet to make any conclusive statements, but from what I see in the article, it is likely that the plane fits the mission I described quite adequately.
_________________ My last name rhymes with 'geese'.
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Post subject: Re: Cirrus SF50 Posted: 26 May 2017, 16:01 |
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Joined: 04/26/13 Posts: 19762 Post Likes: +19430 Location: Columbus , IN (KBAK)
Aircraft: 1968 Baron D55
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Username Protected wrote: This is a piloting issue not an equipment issue and certainly not a jet issue. The same argument can be made for the SR22 not having anti-skid or a reversing prop. The SF50 VREF is reported as 85 knots. The SR22s is 79. If the SF50 is in danger of overrunning the runway so is the SR22 for the same reason, and it's not the lack of anti-skid or reverse thrust.
You may argue that residual thrust from the jet engine is a factor, and I'll grant you that, but I would say that it is insignificant to the calculation, especially compared to approach speed, which is directly controllable by any pilot. Weight is significantly higher. No drag from prop. Yes and yes. How significant is any of that when you are touching down at 80 knots? How short does the runway have to be before it really matters?
_________________ My last name rhymes with 'geese'.
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Post subject: Re: Cirrus SF50 Posted: 26 May 2017, 16:07 |
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Joined: 01/31/09 Posts: 5233 Post Likes: +3026 Location: Northern NJ
Aircraft: SR22;CJ2+;C510
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Username Protected wrote: Yes and yes. How significant is any of that when you are touching down at 80 knots? How short does the runway have to be before it really matters?
How contaminated and slippery does the runway need to be before it matters? Unless you are strictly a fair weather flyer.
_________________ Allen
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Post subject: Re: Cirrus SF50 Posted: 26 May 2017, 16:35 |
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Joined: 08/20/09 Posts: 2394 Post Likes: +1857 Company: Jcrane, Inc. Location: KVES Greenville, OH
Aircraft: C441, RV7A
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Username Protected wrote: This is a piloting issue not an equipment issue and certainly not a jet issue. The same argument can be made for the SR22 not having anti-skid or a reversing prop. The SF50 VREF is reported as 85 knots. The SR22s is 79. If the SF50 is in danger of overrunning the runway so is the SR22 for the same reason, and it's not the lack of anti-skid or reverse thrust.
You may argue that residual thrust from the jet engine is a factor, and I'll grant you that, but I would say that it is insignificant to the calculation, especially compared to approach speed, which is directly controllable by any pilot. Weight is significantly higher. No drag from prop. And they couldn't have made up for it with larger brakes...?
_________________ Jack Stull
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Post subject: Re: Cirrus SF50 Posted: 26 May 2017, 16:45 |
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Joined: 01/31/09 Posts: 5233 Post Likes: +3026 Location: Northern NJ
Aircraft: SR22;CJ2+;C510
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Username Protected wrote: And they couldn't have made up for it with larger brakes...? Small jets have small wheels and tires which limit rotor size. You also have brake energy limits to deal with. Larger brakes will generate more heat which the tire and wheel must dissipate without the fusable plug in the tire blowing.
_________________ Allen
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Post subject: Re: Cirrus SF50 Posted: 26 May 2017, 16:56 |
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Joined: 11/06/10 Posts: 11885 Post Likes: +2848 Company: Looking Location: Outside Boston, or some hotel somewhere
Aircraft: None
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Username Protected wrote: How contaminated and slippery does the runway need to be before it matters? Unless you are strictly a fair weather flyer. Rain and water, unless coming down so hard you hydro plane, I do not think will put many GA runways out of contention. Now ice, snow... yeah, a turboprop is much safer (at least landing, not sure about taxi aspects). The point you made about runway excursions, is with planes which have a Vref approach 115. Therefore, we are discussing a difference between 85 and 115. No we need an engineer of physics expert to come along and cover how much the difference really is in terms of energy. But from what I recall, a 1/3 increase in speed effectively doubles the amount of kinetic energy. That is a big difference. Tim
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Post subject: Re: Cirrus SF50 Posted: 26 May 2017, 17:02 |
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Joined: 01/31/09 Posts: 5233 Post Likes: +3026 Location: Northern NJ
Aircraft: SR22;CJ2+;C510
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Username Protected wrote: How contaminated and slippery does the runway need to be before it matters? Unless you are strictly a fair weather flyer. Rain and water, unless coming down so hard you hydro plane, I do not think will put many GA runways out of contention. Now ice, snow... yeah, a turboprop is much safer (at least landing, not sure about taxi aspects). The point you made about runway excursions, is with planes which have a Vref approach 115. Therefore, we are discussing a difference between 85 and 115. No we need an engineer of physics expert to come along and cover how much the difference really is in terms of energy. But from what I recall, a 1/3 increase in speed effectively doubles the amount of kinetic energy. That is a big difference. Tim
Mustangs, Eclipses and Phenom 100s have slid off the end of runways. If there is no damage except to the pilots shorts they don't get into an NTSB report. SF50 is not going to be significantly different then those aircraft.
Folks try and make the SF50 to be "different". It has all the aerodynamics and limitations of other small turbojets.
_________________ Allen
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