Stall speed & Safety?

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flyingclay
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Stall speed & Safety?

Postby flyingclay » Sun Aug 15, 2010 12:32 pm

as I observe LSA, my thought would be those with lower stall speed would be safer. However I want to have the capability cruise at the upper speeds allowed under SP if I wanted to get to destination quicker etc. It appears the Piper Sport has one of the slowest stalls I've seen and the cruise speed seems to be at the upper limit also. How does the PiperSport seem to have the wide gap as the others do not and is this a positive or negative? Curious as to some different opinions on this.

zdc

Re: Stall speed & Safety?

Postby zdc » Sun Aug 15, 2010 12:53 pm

flyingclay wrote:as I observe LSA, my thought would be those with lower stall speed would be safer. However I want to have the capability cruise at the upper speeds allowed under SP if I wanted to get to destination quicker etc. It appears the Piper Sport has one of the slowest stalls I've seen and the cruise speed seems to be at the upper limit also. How does the PiperSport seem to have the wide gap as the others do not and is this a positive or negative? Curious as to some different opinions on this.


I talked to a Piper Sport owner at OSH. He said that cruise speed was about 105 kts with the passenger seat occupied and about 110 kts solo. That was his experience and I haven't talked to any other Piper Sport owners. That is not to say that in testing that the Piper Sport didn't cruise at 120 kts. The only owners of an LSA that I have talked to that claim a 120 kt cruise speed are Jabiru owners . According to them, it has the capablity to go a little faster than that but the tach is redlined to keep it from exceeding the allowable max speed for an LSA. In Australia, the Jabiru is a 4 seat acft with a MGW higher than an LSA. Jabiru salespeople like to make that fact known. One can draw their own conclusions from that fact.

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CharlieTango
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Postby CharlieTango » Sun Aug 15, 2010 1:51 pm

my ctsw cruises at 125kt TAS. the biggest downside to the big speed range is a big range of pitch attitudes. 40 degrees to -6 (-12) is a big range and full flap landings take some getting used to.

back in 05/06 i settled for a high wing cause the low wings didn't have the speed economy.

flyingclay
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Postby flyingclay » Sun Aug 15, 2010 2:27 pm

what do you mean by "speed economy"? And how does "high wing" effect it etc..?

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CharlieTango
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Postby CharlieTango » Sun Aug 15, 2010 2:38 pm

forgot the slash, i meant speed/economy, the 2 go hand in hand and are mostly a result of lift/drag and power/weight.

when it comes to SLSA you are somewhat locked in to a power/weight ratio so in this case lift/drag is the determining factor.

big flap range comes into play, the ct's composite molded design allows for less drag.

the high wing (especially when cantilevered) seems to produce best l/d, i'm not sure why. this seems to be true for SLSA but not true in general.

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dstclair
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Postby dstclair » Sun Aug 15, 2010 3:36 pm

I measure and recorded my TAS and various settings/altitude for my Sting S3 this past spring at around 200 lbs under gross. Basically, I saw 118 kts at 6100 density altitude and 5200 rpm and 114 kts at 5000 rpm. If I want to push to 5400 rpm, I'd go over 120 kts.

Was just tooling around the patch yesterday morning before the 105 degree heat hit and was doing 110 kts TAS, 5400 DA, 4900 rpm and 50 lbs below gross.
dave

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Postby ArionAv8or » Sun Aug 15, 2010 4:08 pm

I am not sure about the whole speed/economy thing but I can tell you my Jabiru 3300 powered Lightning LS-1 will cruise at 120 kts all day long at 2850 RPMs @ gross. Like most LSAs out there it only uses 5.0 gph to make 120 kts. When I researched aircraft to purchase the PiperSport was the other plane that made my shortlist. One of the reasons I went with the LS-1 was that it could actually fly at 120 kts and the best I got out of the PiperSport was 113 TAS. That is not to say they are not a great aircraft, just not for me. Not that the speeds are much different from most LSAs on the market but I land at 50 kts over the fence and have a stall speed of 39 kts with full flaps. I also like the smooth lines of a composite aircraft, and since I hanger mine it should not be a problem. There are some great planes out there and I take nothing away from any of them. I said before in another post that I DO NOT believe the perfect plane has been built yet and they all have their pros and cons. You just have to pick the plane that is right for you. The CTs and the PiperSports are both great planes, I just like my LS-1 better. Thank goodness we live in America and have the right to choose what we want, and have the freedom to voice our opinion.

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Postby Jim Stewart » Mon Aug 16, 2010 11:11 am

I believe that a high wing and a ballistic parachute are far more important safety-wise than 3-4 knots of slower stall speed.

flyingclay
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Postby flyingclay » Mon Aug 16, 2010 1:37 pm

why high wing?

KSCessnaDriver
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Postby KSCessnaDriver » Mon Aug 16, 2010 2:16 pm

Jim Stewart wrote:I believe that a high wing and a ballistic parachute are far more important safety-wise than 3-4 knots of slower stall speed.


I believe a BRS system decreases safety just as much as it increases it. First, you've got pilots who think since they have the system, they can put themselves in more challenging situations, and rely on it. Secondly, should some sort of incident occur, resulting in a post-impact fire, you now could potentially have an unfired rocket sitting on a burning pile of stuff. Not a place I want to be.
KSCessnaDriver (ATP MEL, Commerical LTA-Airship/SEL, Private SES, CFI/CFII)
LSA's flown: Remos G3, Flight Design CTSW, Aeronca L-16, Jabiru J170

Jim Stewart
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Postby Jim Stewart » Mon Aug 16, 2010 2:25 pm

flyingclay wrote:why high wing?

So I can exit the plane if it's upside down.

flyingclay
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Postby flyingclay » Mon Aug 16, 2010 2:31 pm

KSCessnaDriver, so it sounds that the wisest would be to have the parachute and be disciplined to not fly into situations you wouldnt if you didnn't have it.
Also, KSCessna Driver, Would be interested to know what your observations are on the differences of the 4 LSA's I noticed you have flown. Thanks.

Jim Stewart
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Postby Jim Stewart » Mon Aug 16, 2010 2:34 pm

KSCessnaDriver wrote:
Jim Stewart wrote:I believe that a high wing and a ballistic parachute are far more important safety-wise than 3-4 knots of slower stall speed.


I believe a BRS system decreases safety just as much as it increases it. First, you've got pilots who think since they have the system, they can put themselves in more challenging situations, and rely on it. Secondly, should some sort of incident occur, resulting in a post-impact fire, you now could potentially have an unfired rocket sitting on a burning pile of stuff. Not a place I want to be.


I haven't seen any statistics to confirm your view. OTOH, BRS shows 250 saves to date. Even if half of those were due to people overreaching their skill level, that still 125 saves. Besides, people overreach their skill level in all kinds of planes every day.

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Postby KSCessnaDriver » Mon Aug 16, 2010 2:47 pm

Jim Stewart wrote:I haven't seen any statistics to confirm your view. OTOH, BRS shows 250 saves to date. Even if half of those were due to people overreaching their skill level, that still 125 saves. Besides, people overreach their skill level in all kinds of planes every day.


There wouldn't be any to confirm it. It would be too hard to quantify it. Perhaps not with the LSA category, but in some of the other planes (aka SR-22) with the BRS equipped, there are pilots who think having a parachute makes it safer to launch into ice or other conditions they wouldn't otherwise.

My personal opinion on flying a BRS equipped aircraft, is the only time I'm pulling is if the plane is coming apart. I'm not willing to be an occupant in an uncontrolled airplane when the thing is still flying fine.
KSCessnaDriver (ATP MEL, Commerical LTA-Airship/SEL, Private SES, CFI/CFII)
LSA's flown: Remos G3, Flight Design CTSW, Aeronca L-16, Jabiru J170

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dstclair
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Postby dstclair » Mon Aug 16, 2010 2:56 pm

I believe (or I hope) that most of us will fly the airplane in an emergency as long as you can, well, fly the airplane. The BRS (or in my case, the GRS) is an important piece of backup safety equipment. Each owner has their choice but the insurance companies seem to like them -- lower premiums for parachute enabled aircraft.

What happens when the pilot is unable to fly and the passenger isn't a pilot? BRS just might save a couple lives.

I also posted this before but there are many areas we fly over that are not the most hospitable for landing. A vertical landing might come in handy in these places in an emergency, as well.
dave


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