A paper I read long ago concluded that injure severity in crashes with small airplanes was proportional to the landing speed to the power of 3. I found that interesting because that is fairly close to the much more solid statistics about car crashes.
Obviously construction and ergonomics and crash angle play their parts in the equation, but apparently landing speed still showed a visible pattern in the statistical picture.
RobertL18C wrote:
Cub: that it is a strong, simple, safe airplane that can fly slowly enough to just barely kill you.
The Piper Cub is slow enough that it could potentially be a very safe aircraft, but it isn’t. It has bad stalling manners (compared to modern trainers), it has a fuel tank directly in front of the cabin, and it has a lot of unprotected structure in the cabin close to the occupants.
Yet… I once spent a merry evening trawling through ntsb reports (you can search by aircraft type). I don’t recall the figures but an engine failure and off airfield landing in a cub was almost never fatal. An engine failure in a LongEZ was very bad news indeed.
A lot of forced landings in cubs were probably not reportable either, so the figures are likely even better for the cub than the ntsb database would suggest..
Do airbags make sense, given the weakness of the cockpit structure, compared to modern cars? A GA cockpit tends to more or less disintegrate in any powerful impact.
huv wrote:
It has bad stalling manners (compared to modern trainers)
That’s the first time I’ve heard the Cub stalling manners to be described as “bad”!
alioth wrote:
That’s the first time I’ve heard the Cub stalling manners to be described as “bad”!
Aviation Consumer, March 2016, “Super Cub Wrecks”: “Stalls and low flying combined to lead to 17 accidents. Two involved ranchers who were using their Super Cubs to herd cattle and crashed. Low altitude stalls proved fatal in four accidents. With no camber on the horizontal stabilizer, the Super Cub often rolls rapidly following a cross-control stall—and it can take several hundred feet to recover. In Alaska, those are known as “moose stalls” from fatal low-altitude stall crashes of pilots looking for game. In our review, all of the low-altitude stall/incipient spin crashes also involved severe post-crash fires.”
Update. I just checked Aviation Consumer on accidents with the Piper Warrior. The proportion of registered stall accidents with the Warrior is 4% against 11% and 13% quoted from two different articles about the Piper Cub.
Notwithstanding, I would imagine the stall accidents with the Warrior would be nearer 11% and 13% if it were flown like those Cubs (routine very low and slow flying)
Yes, that may explain part of the difference. But the difference in stall characteristics and fire-proneness remains.
The Super Cub has tanks in the wings, the Aviation Consumer article is behind a paywall so not sure whether they give statistics for the Cub and Super Cub and the many variants.
The so called ‘moose stall’ has been a subject of discussion for many years. The FAA CPL has some useful ground reference manoeuvres which is a pity EASA has not chosen to emulate. The manoeuvres are in fact designed to train against the illusions of low level flight and maintaining co-ordinated flight.
What has provoked discussion is that many Super Cub stall/spin accidents have been while the aircraft was flown by highly experienced bush pilots with thousands of hours of low level, co-ordinated, manoeuvring flight. One theory is that the upset is not due to crossed controls resulting in a skidded turn, but due to the aircraft flying into its own wake, usually on the second orbit. i.e. in a very a co-ordinated turn! The Super Cub is draggy and high lift so perhaps the wake vortices are pronounced for such a light aircraft (although an Alaskan SC is typically around 2,000 lbs gross)?
I am not sure if this theory stands up, but the ‘moose stall’ is easily avoided by flying a rectangular pattern, and not a close orbit. At Super Cub speeds the low turning around a point exercise is below 500 feet agl, so not an ideal aircraft for a FAA CPL ride.
I had not heard the theory about the uncambered stabiliser. Some people put vortex generators on the underside of the stabiliser, but the modern variants retain a flat plate stabiliser so I doubt it is a design issue.
Anyone who has flown a Super Cub will recognise that the stall characteristics are very benign, and it takes a lot of provocation to initiate an autorotation, unless the aircraft is poorly rigged, and there are a few of those flying.
As we’re on the topic of crash worthiness.
Most GA aircraft, or at least the bulk of the population, are designs from the 1950s. It’s only in later years that regulations have demanded crash worthiness of some sort, but most aircraft actually used in clubs, schools or for personal enjoyment are either old, or old designs. As far as I understand, the C172 and PA28 structures are essentially unchanged from the original TC. They may be fitted with 26G seats, but that’s about it.
So, how do these aircraft compare? Is it fair to say that a Cirrus or Diamond is safer from this perspective than a C172 or PA28?
If so, is it really an acceptable gamble to invest in 40 “new” C172s for your training organization knowing that they are inferior in this regard?
If you were able to chose a brand new 1950s Ford Taunus (fitted with bluetooth connectivity ofcourse) over a Mondeo as your next rental, which would you chose?
