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I have noticed that Cessnas seem to have a 10 know slower stall speed
then the comparable Piper model. Does anyone care to comment whether
this design difference makes the Cessnas safer for weekend pilots?It is interesting to note that the airspeed indicator in a 206 shows
the plane capable of flying at 47 knots, whereas a Saratoga needs to
be going 59 knots to stay in the air. This also seems to translate to
shorter (1350 vs 1750) landing distances over a 50' obstacle.
Obviously a big concern of flying a single engine aircraft is engine
failure, and the ability to land on a postage stamp is a very
desirable trait.So... Is the Cessna design safer in that respect?
-- David Sanford, November 11, 2009
There is no "comparable Piper model" to a Cessna 206! The Saratoga is a fast airplane for a family going from paved airport to paved airport. The 206 is a slow airplane for a company hauling mail to a gravel strip in Alaska. You can't land a 206 with the gear up. But you might die of boredom before you get to your destination....
-- Philip Greenspun, November 12, 2009
You probably hit on one of the most under recognized safety issues in aviation. The slower you can land the less energy you have to dissipate. In a crash landing at 80 kts you will plow into obstacles with four times as much kinetic energy as you would at 40 kts. Cessna and Diamond Aircraft have much longer wings than comparable Piper, Beech, Socata, and Cirrus aircraft. Many of the LSA�s have wings that are less than 30 feet long.A higher aspect ratio gives you more control as your approach stall speed, you are less likely to have one wing drop. Higher landing speeds are fine for aircraft with greater mass. They will be less vulnerable to variable gusts and wind shear than say a Cirrus. You do have more control at higher airspeed and a good study might prove my idea wrong that you want to land at the slowest possible speed at which you still have full authority over the aircraft. NASA was behind the study of the wing design that Cirrus uses so it made it an easy decision on the part of the FAA to rubber stamp all the required paperwork but I wonder whether the concept of wings with a dual stall design so that the first stall serves as a warning that a more serious stall is approaching makes sense on planes with mass of less than 12,500 pounds. Or whether pilots with less than several hundred hours of experience should be flying them.
Cirrus does give you an option to pull a parachute and that will certainly make for a �short field landing� but I am not aware of anyone who has built in any means to control your path, so no telling whether you will land in the middle of a soft, freshly plowed field or the edge of a high rise building, on jagged rocky terrain or large body of water.
-- Richard Miles, November 11, 2009
Richard,As a single engine plane pilot, my obvious concern is possible engine failure. While many hi-performance planes offer higher cruise speeds, they usually do so at the expense of a higher stall speed and longer landing distances. (It is interesting that the SR-20 requires a whopping 2600 feet to land over a 50' obstacle) The idea of a single engine plane that can't fly (or crash) at slow speeds makes me very nervous. It would seem that you are setting yourself up for a very difficult situation in the event of an engine failure. That leaves me thinking that the "old" style Cessnas provide the greatest margin of safety for the weekend pilots. I would expect that a 40 kt crash would be much more survivable than a 60 knot crash, unless both result in a post-crash fire. Have you seen any data to indicate how often an off-airport landing results in a fire, and whether the faster flying planes are more likely to burn?
-- David Sanford, November 12, 2009
Phil,The wikipedia article on the Cessna 206 lists just one comparable airplane: the Piper Saratoga. Piper and Cessna have been slugging it out for decades. Warrior vs 172, Dakota vs 182, and Saratoga vs 206. At different times different versions of the planes had fixed gear, and others had retractable gear. I got my commercial ticket in a 172 Retractable, for example. I think that if you compare the cruise speed of the fixed gear Saratoga to the fixed gear 206, you will find them to be within 5 or 10 knots of each other. My original question was why the stall speeds of the Cessna line tend to be 5 to 10 knots slower, and whether this results in a better safety record. I was doing some reading of NTSB accident reports earlier today, and while I did not come to any conclusions about my original question, I sure did notice that SR22s are prone to catching fire upon crashing. (Wow!) That has me wondering about the causes of post-crash fires, and which planes are most prone to this problem. I need to do more reasearch, but my guess is the higher the impact speed, the more likely it burns. As you are from Massachusetts, I'm sure you are familiar with the Easton Angel Flight crash last year. Not pretty.
-- David Sanford, November 13, 2009