Blue on Top

1. The worst stall characteristics (conventional configuration) are at aft CG and LIGHT weight. This is the configuration/condition where the tail power is the greatest ... and the tail power required is the least. Flaps have a tendency to make the stall characteristics better, too, as the flaps drive the separation inboard (where the flaps are located). 2. The C210 was bent (or wing(s) was(were) not installed/adjusted properly). All certificated airplanes must be stalled from level flight and roll must be kept within 15 degrees. This is true power ON (75%, test pilots aren't high-risk takers) and power at IDLE (highest stalling speed). Yes, the margins widen a little for accelerated and turning/accelerated stalls. None are allowed to be violent. The newest of those airplanes left the factory 36 years ago, though. As an add on to "2" above, this is an aha moment to those doing "full power" stalls. Certification for power ON stalls requires only 75% power. Flight Test is not going to stall an airplane at sea level altitude (only place where full power exists) as there is not enough room to recover if something goes bad. Those stalls are typically flown at 5,000' where there is room to recover ... most of the time. We lose test pilots from stalls and spins ... even with an upset recovery parachute installed on the tail. Fly safe.

All: Please remember that the Mooney wing is structurally different than almost all other small, GA, wings ... until one gets into more modern, small, business jets. The Mooney wing does not transmit wing bending loads into the fuselage. The attach bolts take only (double) shear loads of pure lift loading. They are not like a Beech, Piper, etc. that attach at side of body.

These configuration iterations have been done many, many times before ... especially now with CFD being able to run multiple configurations in minutes. There is a good reason why airplanes are configured "conventionally" - big wing up front and small stabilizer in back. It's the most efficient configuration. IF a surface stalls (it needs to be the forward one to make the recovery stable - the most forward wing of a biplane (normally the upper ... except in the case of the Beech "Staggerwing"), a canard, or the main wing of a conventional configuration. I say "IF a surface stalls" because most conventional configured airplanes don't aerodynamically stall at forward CGs. In a Mooney, it may be possible to run the trim nose UP far enough, but a C180/182 will not aerodynamically stall at forward CG. The tail (horizontal stabilizer) should never stall. The results will be a violent nose down pitching moment. These cases are typically only in Flight Test (and very, very rare) and often end with fatal results (and often the aircraft coming apart structurally). This is why tailplane icing is such a huge issue/problem if it happens. The tailplane also accrues ice significantly faster than the wing (smaller leading edge diameters collect ice quickly). In other words, if you see a little ice on your winds, there is more on your tail. PS. Although Boldmethod has pretty pictures and cool, moving, graphics, ...

Yes, the Stearman does have positive camber (similar to the wings and opposite to most other aircraft). The reason is that the tail is VERY statically heavy. I have heard one owner state that the tail weighs 600 lbs. on the ground. The Wright 1911 glider was that way (pictured below) for the same reason ... and many model airplanes, too.

I don't think he does as much now. Investors buy dreams. Look at Uber Elevate (no longer owned by Uber ... hint, hint). Any good engineer or physicist will say it takes much more power to vertically lift any weight with multiple, small diameter rotors than a helicopter, ... and helicopters are not known for being efficient. Helicopters need a power (thrust) to gross weight ratio of about 1:1.1 or 1.2. In other words, a 1000 lbs. helicopter needs to produce 1100 to 1200 lbs. of thrust to lift off. An airplane is typically 30% or less. Aerodynamics have not changed since the beginning of airflow, but our knowledge of how fluid flow works has ... especially in the last 30 years. Here are a couple topics close to home (the Mooney heart). Fixing landing gear on a Mooney would cost 7-8 knots, maximum, not 20-25 between the M20C and M20D models, and the useful load would increase 100 lbs. or so. Great tradeoff in my opinion ... especially with insurance rates figured in. Mooney airplanes could be widened 8"-9" (similar to a Cirrus) with very little drag penalty (4-5 knots or less). People don't want to believe the real data.

@Will.iam: @Bob - S50 gave a great reason. I also like the "stab" pun, too! Now we'll get a little more into it. Downwash from the canard also affects the main wing (lowering the main wing local angle of attack) ... but only over the span of the canard. In other words, the angle of incidence of the inboard section of the main wing needs to be higher than the outboard section of the main wing. BUT, the downwash from the canard varies with the amount of lift being produced. Therefore the main wing inboard section needs to have a variable incidence angle with the outboard section incidence angle remaining the same. So we compromise ... with a fixed angle of incidence for the whole main wing. As a result in cruise, the Starship inboard wing has roughly 1000 lbs. of down force! Putting flaps on a canard design just makes all the above even more complicated ... as was learned on the Starship. Yes, the same is true with an aft tail configuration, but the whole stabilizer is in the same downwash of the main wing. With a fixed stabilizer, we design for minimum cruise drag to set the horizontal stabilizer angle of incidence. On our Mooney aircraft, we trim the stabilizer to the best angle of incidence. Oh, and those pusher propellers ... they have no prayer of being efficient being downstream of the canard, fuselage, main wing, nacelle, exhaust, etc.

Thanks! I am not fluent in French. I think that I have read this report, but I also think that there was a lot lost in the interpretation of the cockpit voice recorder (CVR) and in the translation from French to English. Bottom line for me is that this accident was a long chain of events: very abnormal event, poor training, too much correct information to the pilot and too much incorrect/misleading information to the pilot. Hopefully we'll learn from this tragic event.

NO!!! on both airplanes. Canards AND composite airplanes are inefficient ... economically, weight and aerodynamics. As for the 201, it would cost about $50K less than an Ovation. Still want to bring it back? The 201 didn't come with air conditioning, leather seats or a G1000NXi. Still want one?

Agreeing with @GeeBee. In addition, one doesn't need an AOA indicator to have AOA. It is built into other systems ... and that needs to be taught to pilots. AOA and airspeed are totally different and independent systems (that knowledge would have saved AF447). The CAAs messed it up, too, saying stall warning can't go off during takeoff. In the case of AF447 and at an airspeed below 60 knots, the AOA system is disabled. As the airplane was held in the stall (not deep stall, which is an aerodynamic flow problem), the INDICATED airspeed went above and below 60 knots ... turning the stall warning (stick shaker) ON and OFF. Stick shakers (stall warning, >7 knots or 7% before aerodynamic stall) and stick pushers (stall barrier ... 2 to 5 knots before aerodynamic stall) are driven solely by AOA. Single input for shaker, and dual input for pusher. Those pretty colors on the side of the vertical airspeed tapes on PFDs of Part 25 airplanes and high end Part 23 airplanes are also driven solely by AOA (it is just put on the airspeed scale so pilots don't have to think as much or read another instrument. For example, if the pitot tube(s) got blocked at 100 knots, the red arc for stall, the yellow arc or cross-hatched red arc for stall warning (if in that system), and the green or blue carat for Vref (1.3Vs) will still move up and down properly. In that case, the proper way to fly an approach is with the Vref carat in the middle of the "T" speed (current airspeed). In the example above, the real indicated airspeed would be 130 (not the 100 that is stuck in the window). As for swept wing airplanes stalling poorly, quit repeating data from the '30s and '40s. The best stalling airplane in Textron Aviation's Cessna fleet is the Citation X. It stalls inboard out and better than a C172 or C182. We tailored it that way.

Full fuel payload in a small business jet is often the crew plus 2 or 3 passengers. It is not like removing 100+ passengers and luggage from a 737 and calling it a "business" jet.

Business jets are no different ... nor are our Mooney aircraft. Lack of useful load hurts the M20s, too. Taking a passenger out of a business jet would limit sales ... just like adding one helped the CJ2 a lot! The Citation X wing nor horizontal stabilizer has been tested to failure. The coke bottle portion of the fuselage fails first ... beyond 150% of design load. Knowing how much margin one has for future gross weight increases is priceless!

That is the ultimate in design (lightest design to meet the regulations). This is possible with composites as layer by layer can be added/subtracted. Metal on the other hand only comes in specific thicknesses. Going from one thickness to the next will add lots of margin ... and some weight. A good example is bolts in the flight control systems. An AN3 will handle all the loads really well. A pilot is not going to double shear an AN3 bolt ... even with the mechanical advantage of the system. BUT, a mechanic can (and has on many, many occasions) over-torqued (stripped) the nut. Today, we will not design a flight control system with anything smaller than an AN4 bolt. Remember the 50% margin is to allow for: corrosion, mis-install, fatigue, tolerances, etc.

... and the actuator (the weakest link ... that takes pitching moment of the horizontal (and drag of the vertical). I have been told that the design is fail-safe in that if the actuator physically fails. The two upper bolts, the hinge and the geometry will allow the airplane to be flown home with just the elevator. I would estimate for a flap up (gear down still ) landing.

All fasteners should be designed for shear and not tension. If possible, double shear is much better, too. Double shear, like wing attach bolts, are relatively small compared to what would be required in tension. In comparison, it would be MUCH easier to pop the head off (or strip the threads) of an AN-5 bolt than it would be to shear it in half in two places. Double shear means that there is supporting material on both sides (or the joint is symmetrical without a bending moment at the fastener). In addition, speaking of wing attach bolts, they don't need to be tight, tight, as there should be no load in the tension or compression directions. This is why when riveting 2 aluminum skins together, there is a minimum thickness to countersink the material. Below those values the skins will simply shear the rivet in half. Some thin skins are intentionally dimpled to gain surface area against the skin being able to shear the rivet. If the load was in tension, the skin would simply tear around the rivet head (or pop the head off).

An instrument that is used to show compliance to the stall warning certification regulation. The losing power is in reference to the heating device. IOW, if the probe/sensor loses power, it is considered inop to go into icing conditions. The problem is that IA/A&Ps and Engineers often discuss from very different perspectives. A good example is replacing instrument post lights with an LED strip light. To an IA, this is a minor change (from what I have been told). To an Engineer this is uncertifiable (and makes the airplane unairworthy) because the post lights were used to show compliance to a certification regulation. With that said, the LED lights could be much better than the post lights, but they have not been through the certification process.

I wandered up the wrong alley. This one's full of IAs I should be finding out the TSO information soon. Thanks all.

This is all extremely interesting, and I am not taking sides either way, but I am curious ... I have looked at many, many Safe Flight "Lift Detectors" (switches) and have not noticed the normally required TSO markings. In this case, TSO-C54, "Stall Warning Instruments." This is true for Safe Flight units, Mallory Sonalert (SC628) (and other similar horns) or Cessna reeds (kazoos). What validates that the device can withstand the environmental conditions that it is subjected? And, along those lines, that a repaired unit continues to meet those requirements. Another wrench in the gears is that the switch (and horn) is required to meet a certification regulation, "stall warning". Thanks! All y'all are awesome!

OMG!!! Wow!!! This thread just got super freaky, crazy, mind-blowing for me! The referenced part is a non-heated "switch", so cannot be used on FIKI airplanes. The definition of "switch" here is really, really interesting. I guess a magneto, a strobe, etc. are just "switches", too? The position of that automatic switch shows compliance to an FAA (CAA) regulation. I'm learning! PS. The less expensive part is a grand (literally) improvement.

MSers have yet another outstanding thread. Great information. I continue to learn from all y'all.

Another totally awesome MS thread. I am honored to be in the greatness of all y'all. Thanks for the great information, especially @Minivation on this one.

Great thread! I've heard rumors on price of this switch, but $1000 seems to be on the low end.

Not sure about bamboo, but definitely untreated fabric ... at 45 degrees (to allow the surfaces to warp).

The best material should be used in all cases, and best is relative. If cost and strength to weight ratio are key requirements, aluminum is best. If corrosion resistance and highly contoured surfaces are key, composites often win. It's all relative.

There are small parts of airplanes that are composite, but only for special purposes. The 787, which is composite structure, is composite due to less corrosion issues not it's strength to weight ratio (which is less than aluminum). Even when aluminum mesh is used for lightning strike, the part is heavier because a layer of fiberglass has to be added to the layup so that the carbon doesn't corrode the aluminum. A Boeing engine cowling/pylon is a great example.