Feedback Needed - Homebuilt Aircraft Cruise Speeds

[rwanttaja]

I'm doing one of my periodic deep analyses of homebuilt accident statistics. One aspect is comparing the fatality rate for specific homebuilt aircraft against their configurations and cruise speeds. This is an example of the type of graphic I'm looking to update:
http://www.wanttaja.com/wing_position.jpg

Configuration is easy, but cruise speed is arguable. Below is my initial input to the analysis. I got them through a simple Google search. But I'm sure some folks here know better, and am interested in some feedback.

I realize this is awkward, in that some types of airplanes (such as the Kitfox) have a range of models with a commensurate range of cruise speeds. But I don't need absolute accuracy...plus or minus 10-20 MPH is just going to shift a point on a plot slightly left or right.

I figure it should be a popular topic. You get to argue about your favorite planes, plus you get to call me an idiot for some of my values. :-)



Aircraft

Cruise (MPH)


Avid Flyer

92


Bowers Fly Baby

85


Bushby Midget Mustang 2

165


Cozy

180


Glasair

220


Glastar

135


Harmon Rocket

230


Kitfox

110


Lancair IV

300


Pietenpol Air Camper

85


Rand KR-2

180


Rans S-12

60


Rans S-6

90


Rans S-7

118


Rutan Long-EZ

144


Rutan Varieze

165


Searey

92


Sonex

130


Thorp T-18

175


Vans RV-10

201


Vans RV-3

185


Vans RV-4

201


Vans RV-6

199


Vans RV-7

191


Vans RV-8

210


Vans RV-9

164


Velocity

230


Zenair CH-601

155


Zenair CH-701

85



Ron Wanttaja

[DaleB]

Don't forget the RV-12 at roughly 135-ish MPH. I see 117 - 120 kt TAS in cruise if I'm not dawdling.

[Dana]

Hi, mid, low... what about biplanes?

[Marc Zeitlin]

... Below is my initial input to the analysis. I got them through a simple Google search. But I'm sure some folks here know better, and am interested in some feedback.
Varieze:170 mph
0-235 Long-EZ: 170 mph
0-320 Long-EZ: 195 mph
COZY III: 195 mph
COZY MKIV:190 mph
O-360 Berkut: 225 mph
O-540 Berkut: 245 mph
Velocity: - many variations - fixed gear will be slightly slower than a COZY MKIV, retracts will be slightly faster than the MKIV, and the XL versions will be faster than the MKIV, especially the TXL version. Can't really put only one # on it - it's like saying "Cessnas go this fast"...

There's a fair amount of variation within populations, but these are pretty reasonable estimates for your garden variety canards.
All mid wing.

I also think you're substantially overestimating the RV speeds - the ones I've flown in (or next to) are not as fast as you're listing.

Personally, I'd use kts rather than mph, but that's just me, and it's just a number on the x-axis :-).

All my $0.02 :-).

[Frank Giger]

Hi, mid, low... what about biplanes?

Ron does crashes of airplanes.

Biplanes are more than just airplanes, and so are above such pedestrian efforts as statistics.

(7/8 scale Nieuport 11, 60 mph)

[rwanttaja]

Hi, mid, low... what about biplanes?

Hmmm....this is why I post questions like this, because other folks come up with investigation lines I haven't considered.

My theory is that high-wing aircraft have more structure around the occupants' head and upper bodies, thus their fatality rate is lower. My results generally seem to bear this out.

If it's correct, though, biplanes should be the safest.

So...what are some common biplanes? The Pitts immediately comes to mind. There are 71 Pitts accidents in my 1998-2016 database. Note that these are Experimental Amateur-Built aircraft; I don't include the certified versions.

I type "Pitts" into the search function, and it tells me the Pitts has a 21% fatality rate. This is better than the overall rate of 25%...but I really expected it to be better.

I typed in "Christen Eagle", and was shocked: 37% fatality rate.

What the hey....?

Then I took a closer look at those fatal Christen Eagle accidents. There were 13 of them...and almost half of them (6) were due to maneuvering at low altitude. Low level acro, for the most part. Maneuvering at low altitude has an extremely high fatality rate.

In addition, three MORE fatal Christen accidents fall into a category I call "Failure to Recover"...started a maneuver at a high enough altitude, but for some reason didn't recover before ground impact.

So the Christen comparison isn't too fair...they have a lot of accidents in modes that most homebuilts don't operate in.

Oddly enough, when I took a closer look at the Pitts, the number of cases of Maneuvering at Low Altitude/Failure to Recover were almost the same as the Christen...nine and three, respectively. Plus it had only two more fatals than the Christen. This is interesting, since the Pitts saw more than twice as many total accidents.

BTW, both aircraft have a "Maneuvering at Low Altitude" rate more than three times higher than the general homebuilt population.

Stardusters, on the other hand, have a fatality rate of about 15%, much lower than average. Only eight fatalities for 55 accidents, but half of them are Maneuvering at Low Altitude or failure to recover. However, one case was builder error, in that the elevator weld gave way during a low-level roll.

Anyway, good thought, and I'll incorporate it into my analysis.

Ron Wanttaja

[Dana]

Regarding Pitts vs. Christen, many Pitts's are homebuilt whereas the Christen is always factory built. As a result, the Christen will appeal more to the "I want it now" type of pilot with money who buys more airplane than he really should?

Regarding Stardusters (Starduster One, 105mph cruise for mine at least), I can attest to its stoutness after my forced landing and subsequent cartwheel. The Stardusters are less intended for hardcore aerobatics than the Pitts or Christen, which may speak to the kind of accidents.

[CHICAGORANDY]

Forgive an 'uninformed' question. What is the definition of 'fatality rate"? Number of deaths vs number of flights? Number of deaths in any accident? Certain accidents?

Just wondering. I'm presuming you feel there is a correlation between the location of the wing and general crash survivability? That would of course require comparing very similar crashes happening to machines with like mass/weight/velocity/impact angle etc? as well as wing location.

[rwanttaja]

Forgive an 'uninformed' question. What is the definition of 'fatality rate"? Number of deaths vs number of flights? Number of deaths in any accident? Certain accidents?

My definition of Fatality Rate is the number of accidents with at least one fatality, vs. the total number of accidents.


Just wondering. I'm presuming you feel there is a correlation between the location of the wing and general crash survivability? That would of course require comparing very similar crashes happening to machines with like mass/weight/velocity/impact angle etc? as well as wing location.

Certainly, but unfortunately, that's difficult data to extract. Plus, of course, accidents are random events...a fatality might depend on whether the passenger is leaning over to tie his shoe, etc.

I certainly understand I can't *prove* the theory that wing position affects survivability. I'm attempting to find some correlation by using thousands of aircraft in each configuration. The homebuilt accident record provides about 3800 accidents over the 19-year period my database runs.

Obviously, the speed at impact is a very big driver...energy increases by the square of the impact velocity. I'm hoping to use cruise speed to differentiate...but, of course, few airplanes actually CRASH at cruise speed. I'm using cruise speed just to indicate the approximate operating range of the aircraft. An RV-6 approaches faster than the cruise speed of Frank's Nieuport, but by using cruise speed as the factor the difference in capability is acknowledged.

One drawback is that there ARE no quantities of high-performance high-wing homebuilts. There are a few Aerocomps, even fewer Stallions. So it's hard to get data in the higher-performance regime.

There is some correlation in the production-aircraft world. The Cessna 172 has a fatality rate of 12.%, while the PA-28 (through the -181) it's 19%. The Bonanza and the Cirrus both have rates in the low '30s, while the Cessna 210 is 20%. However, the 210 has a lot of landing-gear-related and fuel starvation accidents, which usually aren't fatal.

Ron Wanttaja

[Dana]

To get meaningful results you'll have to consider and group the class of accidents. As you say, some accidents are less likely to be fatal (a gear up landing, for example, or a forced landing in a rough field with no stall spin) regardless of the aircraft configuration. And there are other variables... conventional engine in front, vs. pusher (VariEZ) vs. pylon mounted engine (Searay, Kolb, etc.) might be significant. And many if not most of the "slippery" airplanes that pick up speed fast when things go wrong are low wing, whereas biplanes probably have the lion's share of accidents due to low altitude aerobatics.

The thing with homebuilts, it's a pretty small statistical universe with wide variation. Looking at GA accidents might be more instructive, not only are there a lot more of them, but a Cessna 172 is, for example, pretty similar to a Cherokee 180 except for wing location.

[Bill Berson]

Pazmany said low wing is better in an upright crash with wing structure below. An inverted crash obviously favors high wing. But inverted crash is usually fatal. So who knows? Too many variables.

[Dana]

Pazmany said low wing is better in an upright crash with wing structure below. An inverted crash obviously favors high wing. But inverted crash is usually fatal. So who knows? Too many variables.

But if the plane noses over and comes to rest inverted, the high wing is probably better. High wings usually have more structure in the upper half of the cockpit (think roll cage).

[Kyle Boatright]

I also think you're substantially overestimating the RV speeds - the ones I've flown in (or next to) are not as fast as you're listing.

All my $0.02 :-).

A lot of it is about engine choice. My 160 hp RV-6 can cruise at 190 mph, but I'm generally running 60-65% and 175 mph. The skinnier airplanes and the ones with more HP go a bit faster. The ones with poor attention to detail go slower. That's for sure.

[Bill Berson]

But if the plane noses over and comes to rest inverted, the high wing is probably better. High wings usually have more structure in the upper half of the cockpit (think roll cage).

Yes, a high wing has structure in a roll over. But it is the initial impact that kills. A roll over is generally low impact. I saw a C-172 and a Glastar flip over. Both tipped over very slow with no injuries at all. Sure, the low wing needs some roll bars or cabin structure enough to keep the pilot from hitting

[Anymouse]

Didn't see a Tango on your list. I get an honest 180 knots with mine.

I only know of two fatal accidents though, both were more than 15 years ago I think. The first was a fellow that was suspected doing unwise things with the aircraft. Things he was told not to do. The second was a fellow that was scud running and ended up on the side of a hill.

These are both from memory.

[rwanttaja]

Didn't see a Tango on your list. I get an honest 180 knots with mine.
I tend to leave off types with fewer accidents, since it's tough to draw conclusions over only a couple of cases. This is why a number of types aren't included.

On a similar note, I have 17 Nieuport accidents in my database...but no reliable way to tell which are CIRCA/Graham Lee, Aerodrome, Redfern, etc. types. Eleven had VW engines, so I expect they're CIRCA. But, again, not enough accidents to draw conclusions.

I didn't include the RV-12 as it's tough to differentiate the EAB from the ELSAs in the NTSB reports and FAA registry, and my focus is EABs. I attempt to track them, but generally don't include them on any released analyses.


I only know of two fatal accidents though, both were more than 15 years ago I think. The first was a fellow that was suspected doing unwise things with the aircraft. Things he was told not to do. The second was a fellow that was scud running and ended up on the side of a hill.

My 1998-2016 database is showing six Tango accidents in the US, but only one fatal (FTW01LA032, continued VFR into IFR conditions, with icing thrown in). I'm suspecting this is an aircraft nomenclature issue (e.g., aircraft model something that doesn't parse as "Tango"). I'd be obliged for more information, to help tune my database.

Ron Wanttaja

[Bob H]

Pulsar XP is homebuilt, low-wing, with cruise speeds between 120-140 mph depending on engine choice.

[martymayes]

I also think you're substantially overestimating the RV speeds - the ones I've flown in (or next to) are not as fast as you're listing.

They go faster when nobody is around.

[Ron Blum]

This is GREAT information! I hope you find a common thread.

FAA and ASTM are working similar issues with the new re-write. They plot versus stall speed.

i also know from previous work at a GA major that shoulder harness or not was a huge factor.

keep up the great work!

[rv8bldr]

I get 165kts (189mph) as a cross country cruise on my RV-8. Fixed pitch 3 blade Catto, 200hp IO-360, 9.2 gals per hour. I could go faster, but I'm too cheap to burn more fuel :-)

[Frank Giger]

Ron, the number of Airdrome Nieuports, both 11 and 17, are barely in double digits, and true replicas are in the single digits. The vast majority of them are Circa (Graham Lee).

The differences between Circa and Airdrome aren't meaningful when it comes to surviveability; they're both aluminum tube-and-gusset with pop rivets.

I suspect true statistics on wrecks vs injury in inexpensive, light aircraft like these is impossible. Liability without hull insurance is the rule. When I flipped my plane, replacing two spars, the prop, crankshaft, gear leg, brakes, wheels, recover and paint the two wings cost less than 1,500 bucks. It won't show up in a database, as it wasn't reported to the FAA or NTSB (though I did file a NASA report).

Talking within the community, incidents like mine aren't as uncommon as I thought they were. If it doesn't happen in front of the FAA, the cops, or a reporter, it just didn't happen.

If I had the big money put into an RV, though, I'd probably report it properly and file a claim, as those kinds of repairs would be high. And the stats would be more robust.

[rwanttaja]

I suspect true statistics on wrecks vs injury in inexpensive, light aircraft like these is impossible. Liability without hull insurance is the rule. When I flipped my plane, replacing two spars, the prop, crankshaft, gear leg, brakes, wheels, recover and paint the two wings cost less than 1,500 bucks. It won't show up in a database, as it wasn't reported to the FAA or NTSB (though I did file a NASA report).

Talking within the community, incidents like mine aren't as uncommon as I thought they were. If it doesn't happen in front of the FAA, the cops, or a reporter, it just didn't happen.

Or with serious injuries or death, of course.

Otherwise, very true, and not just on the low-buck airplanes. I had previously mentioned a BD-4 accident that occurred at an EAA picnic on an airpark. Chapter members got the pieces stuffed into a hangar before the cops showed up.

Another case involved a taxi accident of another BD-4. The owner argued this didn't qualify as an aviation accident because the airplane hadn't yet been given an airworthiness certificate. Plus it didn't have wings on.

Ron Wanttaja

[Dana]

Talking within the community, incidents like mine aren't as uncommon as I thought they were. If it doesn't happen in front of the FAA, the cops, or a reporter, it just didn't happen.


Otherwise, very true, and not just on the low-buck airplanes. I had previously mentioned a BD-4 accident that occurred at an EAA picnic on an airpark. Chapter members got the pieces stuffed into a hangar before the cops showed up.

Yeah, I've seen more than a few wrecks being tucked out of sight as soon as possible. But with cellphones being ubiquitous nowadays people are just programmed to dial 911 at the slightest provocation, so I suspect even minor accidents will be more likely to be reported.

Of course I was just unlucky, making my forced landing earlier this fall within sight of a major interstate. They demanded I remove the wreckage immediately just so they'd stop getting 911 calls.

[Kyle Boatright]

Yeah, I've seen more than a few wrecks being tucked out of sight as soon as possible. But with cellphones being ubiquitous nowadays people are just programmed to dial 911 at the slightest provocation, so I suspect even minor accidents will be more likely to be reported.

Of course I was just unlucky, making my forced landing earlier this fall within sight of a major interstate. They demanded I remove the wreckage immediately just so they'd stop getting 911 calls.

"The Guys" at small GA airfields are a little more autonomous (anti authority?) and value privacy more than your typical Facebook poster. I've known of a few bent airplanes that were loaded onto an airplane gurney, tucked away into a hangar, and healed themselves without any "help" from persons outside the airport community.

[martymayes]

Or with serious injuries or death, of course.

Otherwise, very true, and not just on the low-buck airplanes. I had previously mentioned a BD-4 accident that occurred at an EAA picnic on an airpark. Chapter members got the pieces stuffed into a hangar before the cops showed up.

Another case involved a taxi accident of another BD-4. The owner argued this didn't qualify as an aviation accident because the airplane hadn't yet been given an airworthiness certificate. Plus it didn't have wings on.


A friend of mine had the engine quit on a T-cart when he was about to enter downwind in the pattern. Could not quite make the runway and the plane flipped over in a field. The locals were there before the dirt settled, one of which was John Swick. After a brief discussion, JS said "the fewer people that find out the better" so they toted the plane to an empty hangar and and had the sight cleaned up in no time. I like that kind of thinking.

I know of a no wings installed accident and the feds said, nope, no intent to fly so it was essentially a go-kart accident.

[flyrgreen]

Ron, the KR2 is significantly slower than the (still) published 180 mph. And I believe that early claim was for top speed, not cruise. Almost no KR's have retract gear anymore (and haven't for many years --- bad original design), and even with the later larger-bore VW engines, cruise is in the 140-150 mph range. Top speed 165-170. The few flyers who have put a Corvair engine in their KR are getting up in that 180-195 area. And loving it!

[Anymouse]

I tend to leave off types with fewer accidents, since it's tough to draw conclusions over only a couple of cases. This is why a number of types aren't included.

On a similar note, I have 17 Nieuport accidents in my database...but no reliable way to tell which are CIRCA/Graham Lee, Aerodrome, Redfern, etc. types. Eleven had VW engines, so I expect they're CIRCA. But, again, not enough accidents to draw conclusions.

I didn't include the RV-12 as it's tough to differentiate the EAB from the ELSAs in the NTSB reports and FAA registry, and my focus is EABs. I attempt to track them, but generally don't include them on any released analyses.



My 1998-2016 database is showing six Tango accidents in the US, but only one fatal (FTW01LA032, continued VFR into IFR conditions, with icing thrown in). I'm suspecting this is an aircraft nomenclature issue (e.g., aircraft model something that doesn't parse as "Tango"). I'd be obliged for more information, to help tune my database.

Ron Wanttaja

The accident occurred on July 1st, 1997, so I guess it's out of your range.

Here's the link anyway...

https://app.ntsb.gov/pdfgenerator/ReportGeneratorFile.ashx?EventID=20001208X08459&AKey=1&RType=Summary&IType=LA

Looks like the NTSB has cleaned up it's database a bit and the older reports are not as detailed as they once were. The report I saw a bunch of years ago went into a bit more detail about the pilot and his "unwise" flying habits. It's only touched on in the link I provided, but I believe that the folks investigating the accident determined that he had done a complete 360 from the top of the trees to impact.

[SamP]

Hi Ron,
Always appreciate your analysis of aircraft accidents. It informs the entire community.
Instead of cruise speed as differentiator, why not use stall speed since most accidents occur during takeoff and landing.


My definition of Fatality Rate is the number of accidents with at least one fatality, vs. the total number of accidents.



Certainly, but unfortunately, that's difficult data to extract. Plus, of course, accidents are random events...a fatality might depend on whether the passenger is leaning over to tie his shoe, etc.

I certainly understand I can't *prove* the theory that wing position affects survivability. I'm attempting to find some correlation by using thousands of aircraft in each configuration. The homebuilt accident record provides about 3800 accidents over the 19-year period my database runs.

Obviously, the speed at impact is a very big driver...energy increases by the square of the impact velocity. I'm hoping to use cruise speed to differentiate...but, of course, few airplanes actually CRASH at cruise speed. I'm using cruise speed just to indicate the approximate operating range of the aircraft. An RV-6 approaches faster than the cruise speed of Frank's Nieuport, but by using cruise speed as the factor the difference in capability is acknowledged.

One drawback is that there ARE no quantities of high-performance high-wing homebuilts. There are a few Aerocomps, even fewer Stallions. So it's hard to get data in the higher-performance regime.

There is some correlation in the production-aircraft world. The Cessna 172 has a fatality rate of 12.%, while the PA-28 (through the -181) it's 19%. The Bonanza and the Cirrus both have rates in the low '30s, while the Cessna 210 is 20%. However, the 210 has a lot of landing-gear-related and fuel starvation accidents, which usually aren't fatal.

Ron Wanttaja

[rwanttaja]

Hi Ron,
Always appreciate your analysis of aircraft accidents. It informs the entire community.
Instead of cruise speed as differentiator, why not use stall speed since most accidents occur during takeoff and landing.

It certainly can be argued either way. However, when I'm looking at fatality rates, I prefer cruise speed for a couple of reasons.

1. It's a better indicator of a high-performance aircraft. If a plane "gets away" from the pilot, a higher cruise speed indicates it would accelerate faster and to a higher speed.

2. There's the difference between dirty and clean stall speeds... which would I use? Dirty stall speed is applicable to landing accidents, while clean stall speeds are more related to stalls in other phases. Note this graphic from an upcoming KITPLANES article...it's tough to decide which parameter to compare. Since most stalls of operational homebuilt occur on takeoff and initial climb, clean stall might be better. But the base/final stall/spin is such an ingrained aspect of our lives, it's hard to fight the dirty-stall idea.
http://www.wanttaja.com/phase.jpg
Discussing it, though, makes me wonder if wing loading might be a better factor than cruise or stall speed. Probably less prone to marketing distortion.

Ron Wanttaja

[Ron Blum]

Note this graphic from an upcoming KITPLANES article...it's tough to decide which parameter to compare.

Discussing it, though, makes me wonder if wing loading might be a better factor than cruise or stall speed. Probably less prone to marketing distortion.

Ron Wanttaja
The fatal accident data for certificated airplanes is very similar in where the accidents occurred. Many, many more are on takeoff and go-around.

wing loading might be good. ASTM is looking at control forces, configuration changes (and resulting forces), etc.

I look forward to your upcoming article!

[rwanttaja]

Note this graphic from an upcoming KITPLANES article...it's tough to decide which parameter to compare.
By the way, there's an official "attaboy" and acknowledgement of your he-man skills (whoops, "gender-person" skills) in aircraft identification if you know what type of airplane I used on that diagram.

To make things a bit easier, here's a three-view:

http://www.wanttaja.com/title_is_no_help.jpg

Ron Wanttaja

[Ron Blum]

Looks like a tricycle gear Druine “Turbulent” with squared off tips ... but one can do anything in the E-AB category :P

[martymayes]

I’ll check the Cal Parker archives and post my best guess....

[rwanttaja]

A couple of hints:

1. It's the younger, smaller, less-popular step-brother of a common homebuilt.
2. All metal
3. If you've seen four of them, you've seen them all.

http://www.wanttaja.com/try_this.jpg

Ron Wanttaja

[Bill Berson]

Bill Warwick's Bantam https://www.planeandpilotmag.com/article/bantam/#.WtzkjetHarU

[rwanttaja]

Bill Warwick's Bantam https://www.planeandpilotmag.com/article/bantam/#.WtzkjetHarU

The winnah!

Ron Wanttaja

[Ron Blum]

I learned something new :thumbsup:

[rwanttaja]

I learned something new :thumbsup:

As for how *I* found out about the Bantam, go into the SPORT AVIATION archives (https://www.eaa.org/en/eaa/aviation-education-and-resources/eaa-magazines-and-publications/eaa-sport-aviation-magazine/sport-aviation-archive/sport-aviation-browse) and see page 82 of the April 2007 issue.

Ron "Still have the parts" Wanttaja

[Ron Blum]

Cool story :)

[Frank Giger]

Ron is making me think again!

Looking at the graphic, it strikes me kind of funny that folks stall on takeoff, and though I know of one fatal wreck that happened that way (test flight #1 in a Nieuport 11 replica), I am trying to figure it out.

Best I can reckon is that apart from test phase fun with engines, it's short fields doing the pilot no favors as he goes for too much max climb to clear obstacles that has to be to blame.

Any enlightenment?

[rwanttaja]

Looking at the graphic, it strikes me kind of funny that folks stall on takeoff, and though I know of one fatal wreck that happened that way (test flight #1 in a Nieuport 11 replica), I am trying to figure it out.

Best I can reckon is that apart from test phase fun with engines, it's short fields doing the pilot no favors as he goes for too much max climb to clear obstacles that has to be to blame.

I haven't attempted to split this out any further. But I'd guess pilot inattention is probably more a factor.

We're continually warned about stalling on the base-to-final turn, and many of us a quivering masses of concentration as we prepare to land. Flying with the power off is a multisensory endeavor, especially with an open-cockpit wire-braced airplane like a Nieuport. You've got the gauge, you've got your ears, and you've got the air rushing by.

But takeoff? Meh. Once the wheels come off the ground, we relax. The engine is the overriding physical and audio feature, and if it's running strong, there's little other physical phenomenae that might warn you the plane is getting slow. You're pulling out your charts, you're planning your turn onto course, you're watching the other planes trying to enter the pattern. The engine's running...who's going to worry?


Any enlightenment?

Enlightenment? Next time you hit a food cart, ask for a Zen hot dog: "Make me one with everything."

Ron Wanttaja

[Ron Blum]

There are a lot of reasons why the stall-spin accident rate is much higher on takeoff/go-around than on landing. Yes, this surprised me when I first heard it, too, but ...

Landing:
1. Initial, target airspeed is 30% above stall speed.
2. Power is low --> therefore little requirement for a rudder input.
3. Airplane is allowed to descend --> therefore, although bank angle may be higher, G-load may not be raised correspondingly.

Takeoff:
1. Initial, target airspeed is only 20% above stall speed.
2. Power is high --> therefore rudder is required to properly coordinate.
3. Airplane is NOT allowed to descend --> therefore any bank angle will increase the G-load
4. Typical pilot reaction to upcoming terrain is to pull back on the control --> increasing G-load and decreasing airspeed.
5. Engine failure with pilots that fail to lower the nose to maintain airspeed.
6. Configuration (power) changes on go-around that cause the nose to go up. The pitch rate may be such that the stall warning is not early enough to warn the pilot that the airplane is going to depart.

AOPA did a great report on stall-spin accidents between 2000-2016 (published during OSH17). I would say that the link is below, but it looks like it didn't paste correctly. If cutting and pasting the address below doesn't work, just Google "AOPA Keep the Wings Flying", and it will come up.

https://www.aopa.org/-/media/files/aopa/home/pilot-resources/safety-and-proficiency/accident-analysis/special-reports/stall_spin.pdf?la=en

Hope this "enlightens" a little; it has for me. This is giving me (and others, too?) sparks to hopefully find potential solutions.

[rwanttaja]

Along these lines, I'd also like some feedback/suggestions as to terminology.

As part of the stall study, I'm looking how often the pilots of specific homebuilt types accidentally stall as part of the accident sequence. I've got it broken down into two basic categories: Stalls that occur out of normal operation, and stalls that happen during the forced landing subsequent to an engine failure.

I think it's an important distinction. Once the engine fails, the pilots are under a tremendous strain, and often the stalls occur out of the unconscious desire to avoid ground contact. On the other hand, a stall that occurs during normal flight might indicate an aircraft design that doesn't provide enough warning, or presents a more difficult recovery.

I'm looking for some nice terminology for those two conditions. Right now, I'm using "Inadvertent Stall" for the cases where there is not a power issue. Might use, "Force-landing stall" for the emergency cases. Trouble is, the stalls during forced landings are "Inadvertent Stalls" as well.

Anybody have some good suggestions?

And just to tease (Spoiler alert): The out of 15 common homebuilt aircraft, the two scoring the best in the "Inadvertent Stall" category are designs that were eventually type certificated under Normal category (with minor changes)....

Ron Wanttaja

[Ron Blum]

This is exactly where a couple of us are trying to take the ASTM committee. By educated guess, all stalls are inadvertent, except those performed >3,000 ft AGL. for training/practice. We are looking at stalls due to primary control inputs, configuration changes (such as flaps), engine failure, power changes, etc.

As you have eluded to, the stall may not be a single event but rather a chain of events that terminated in a stall.

Thanks for the great work!

[Bill Berson]

The "moose turn stall" is named for the situation where a pilot is doing several low and slow circles perhaps with flaps. The airplane gradually gets behind the power curve and can't climb in a turn. But instead of rolling wings level first the pilot instead pulls the stick back and stalls in the turn at 100 feet agl.

[dougbush]

As part of the stall study, I'm looking how often the pilots of specific homebuilt types accidentally stall as part of the accident sequence. I've got it broken down into two basic categories: Stalls that occur out of normal operation, and stalls that happen during the forced landing subsequent to an engine failure.

I think it's an important distinction.
I'm not sure there's a distinction to be made. An engine failure is a dramatic distraction, but if one doesn't understand angle of attack, any distraction will do. I suspect those other inadvertent stalls are precipitated by some lesser distraction.

An unintentional stall says more about pilot training and/or testing than about aircraft design. Anyway, there's a more direct method to evaluate a design: have it test-flown by someone with experience in a variety of aircraft and ask whether it did anything weird.

Different types of planes appeal to different types of pilots, which could account for some variation in frequency of stall accidents. I don't think it's fair to blame the designer for the faults of the pilots who like it.

[Ron Blum]

[QUOTE=dougbush;69943 I don't think it's fair to blame the designer for the faults of the pilots who like it.[/QUOTE]

I would agree that a stall after an engine failure is poor training. Look at the glider world. Gliders have a lot of engine failures (rope breaks) on takeoff. They are taught to think of what to do if the rope breaks on takeoff at different altitudes and with different runway lengths and surrounding terrain. I think the powered world could learn from their example.

Not blaming designers or pilots, I believe that many real world stall scenarios are not addressed by the current regulations. For a couple examples, at what airspeed will full aileron input cause the airplane to depart? And, how long does an inattentive pilot get to react to a stall warning on a go around in an airplane that pitches up abruptly when adding full power in the landing configuration? Both of these are not tested by the regulations.

it’s not who we can blame, but rather what can be accomplished so that we can greatly reduce the number of these fatal accidents.

[Frank Giger]

Ron, there are some things I am not going to test in my aircraft.

[Ron Blum]

Ron, there are some things I am not going to test in my aircraft.
Frank: I agree with you from an E-AB standpoint. From a certificated aircraft standpoint, I think that we (OEMs) should test as much as is reasonable. These organizations know how to approach high-risk testing and have the safety/recovery equipment (spin chute, personal chutes, telemetry, etc.) to do these tests safely. If we learn something there, it can be passed along to the E-AB world. (yes, all airplanes are different). OR ... (and this is where the certification world is most likely going to go)

Stick pushers (or some form of stall barrier system) will become standard on all airplanes. For an OEM it’s easier, cheaper and eliminates an unknown quantity in the flight test program... and the >$2M spin program.

(it is my strong belief that...) Nobody intentionality stalls an airplane at low altitude. Yet the number 1 cause of fatal accidents year after year is pilots controlling the aircraft into a stall. Regretfully, what the NTSB labels “maneuvering” stalls is a large percentage of the accidents.

We, as an aviation community, need to come up with ideas on how to break that fatal chain before the pilot gets to that point.

[CarlOrton]

OK; 49 comments thus far, and only a handful provided data to Ron's original request. My Sonex did 133 mph WOT at 2500'. I usually cruised more at 116 mph for economy, quieter, etc.

I'd like to see the comprehensive data, by model, at some point.

[cub builder]

Regarding the KR-2, most builders are building the stretched version and using either Corvairs, or O-200s with a few using O-235s for power. At last year's KR Gathering, all the new KRs were flying behind O-200 powerplants and not a single Corvair was there, which is not to say there aren't still a number of them flying and under construction. My O-200 powered KR-2S shows 185 mph at WOT, but normal cruise is typically 155 - 160 mph. Some of the KRs that are a newer than mine are a bit faster using the newer wing design. It's also worth noting that the handling characteristics of the stretch versions, while still very light on the controls, are much improved over the original KR-2 design, which should make a significant impact on the accident rate.

My SuperCub Clone at WOT shows 120 mph but also kind of thrashes the plane at that speed. Normal cruise for me is 100 mph... or less depending on how much I throttle back for site seeing and whether I have the doors open.

-Cub Builder