Blue on Top

On a sad note (but it's been years ago), I lost 3 friends in a Challenger accident on takeoff. At the time here in Wichita, we had two major Flight Test centers at the main airport, and Fire and Rescue are briefed often on how and where to get into our airplanes. I am not saying anyone would have survived, but they tried to break into the airplane at the windscreen ... probably the strongest place on the airplane. We even have "cut here" markings on the Test airplanes.

PS. @Fly_M20R My buffing skills are really poor, but I don't need practice. They will never improve. Also, as an aerodynamicist, I know exactly how much wetted area (surface area) there is on an airplane

I'm asking for flames, but that's my job Honestly, though, there are people on both sides of this on this thread, so here goes ... 1) I'll ask a few questions first. Was there a propeller change between these years? Yes, I know they are all constant speed. Even constant speed propellers will be twisted differently for climb (slow speed) and cruise (high speed). In addition, propellers can be twisted and shaped inboard quite differently for cooling reasons. Did the cowl change? Was there a propeller aspect ratio change? Two-blade versus three? 2) At the same weight and conditions, all "J"s should perform the same. But, it was mentioned above that the speed at 50' was raised significantly in the later airplanes. This will definitely increase takeoff distances. Those speeds are typically not changed with less than gross weight takeoff data. As a result, the apples-to-apples comparison at 2740 lbs. is really not apples-to-apples as the newer airplanes still need to accelerate to the higher climb speed. 3) With that said, someone mentioned that the ground roll is also longer in the newer airplanes (but Vs and Vr are the same). This screams of a different propeller to me. If Mooney elected to give up takeoff performance for a little higher cruise speed, that would not surprise me at all. 4) As for wing tip treatments, squared off tips are actually fairly effective as it causes cleaner vortex separations from the wing. Additional span is ALWAYS good. My apologies to @PT20J (I love you, man), but ANY span outboard of the aileron (Mooney geometry) will increase the aileron control forces and their effectiveness. With the additional span (though minor) will cause less wingtip loss ... especially locally at the aileron itself.

@Fly_M20R Chris: Your aero knowledge is good! Cl (lower case el) is the wing section lift coefficient. This is the value that one will find in an airfoil book, and it is a 2D (infinite wingspan) value. On the other hand, CL (capital el) is the wing, as a whole, lift coefficient. It is 3D and includes all the effects of the wing having a finite span. Even the Mooney wing, which is much more simple than we would design today, uses at least a couple different airfoils and has twist (different local AOA at every spanwise location). A wing designed today will not only have at least two different airfoils -root and tip (some have 5 or 6) defined airfoil sections, but the airfoils between those defined airfoils are transition airfoils (not defined per se). In addition, wing twist used to be linear. In other words and if a wing is twisted 3 degrees, at 1/3rd span it would be twisted down 1 degree, at 2/3rds span 2 degrees and at the tip 3 degrees. Tod7 ay, though, we design exactly what we want.1 For example, the new M10 POC had no twist in the flapped section and 3 degrees in the aileron section. This gave us an almost perfect elliptical lift distribution and kept aileron full deflection from stalling the outboard section. We use aircraft AOA because every section (little spanwise slice of the wing) can be related to it. Here a picture would be worth more than 1,000 words, but ... Say the inboard airfoils starts to stall at an aircraft AOA of 14 degrees and is fully stalled at 16 degrees. Midspan at 15 and 18, respectively. Wingtip at 17 and 22, respectively. So, if the aircraft AOA is 16, the very inboard airfoil is fully separated, midspan is beginning to separate, and the wingtip is still flying. Most likely, the aircraft is still flying at this point (but the tail should be buffeting). If aircraft AOA is increased to 17, the inboard section is completely separated, midspan is halfway separated and the wingtip is still flying. An educated guess is this condition is when the pilot says the airplane stalled. Most of the wing is still flying. Rarely does the full wing separate.

You guys are all totally awesome!!! ... and all you say is correct, too! I'll add a couple thoughts, but as I mentioned above, you're all on the right track. As @PT20J mentioned, aerodynamicists don't change the chord line with flap, slat, aileron, etc. deflection. Changing the chord angle would only account for one of many changes (and it's not an accurate method). In other words, the chord length also changes (more on that shortly), the mean camber line changes, a slot may or may not open up, etc. Bottom line is that it is just a different airfoil. As a funny note for those that want to redefine the chord line, where is the new chord line/AOA when a split flap is deployed? The upper surface is still the upper surface (and its trailing edge) but the lower surface has a new lower surface trailing edge. I'll get back to AOA in just a second. One can call flap action whatever they want, as the flap movement isn't any one type of movement. They are simply just definitions. Even a simple flap changes with the hinge position: at the leading edge, in the middle of the leading edge radius (if it even has one), the lower surface, the upper surface, etc. Personally, I would call the Mooney flap a single-slotted flap with some Fowler action. Fowler action just means that it has some aft movement ... which increases the chord and wing area ... which we also don't account for There is a difference between Cl and CL. WHAT??? Cl is the section coefficient of lift (2D, 2-dimensional, infinite wingspan) and CL is the wing coefficient of lift (3D, 3-dimensional, real world). These values are significantly different. This gets us to, "How does an aerodynamicist deal with all these differences?" Simply put, we don't. There is one chord (normally the mean aerodynamic chord), one AOA (the calculations above ignored the fact that the wing is twisted), one wing area (some include the area within the fuselage - and how, some don't; some include wing tips/winglets, some don't, etc.). All of these values are simply reference values. Yes, if we change the reference values, the absolute, numeric values of the other parameters would change, but we are simply trying to duplicate the real world (which doesn't change with our definitions. So, how do we do it? Aircraft AOA is defined as the angle between the longitudinal axis of the airplane and the relative wind well out in front of the airplane. We calibrate this using angle of pitch (AOP) from the AHRS while performing level flight speed sweeps. It doesn't matter if the AOA is 3.5792 degrees or 5.0 degrees. It's just a number, and it's all relative. Yes, we try to mate the wind tunnel and CFD as best we can. Now for the elephant. Aerodynamicists relate everything to aircraft AOA. Each spanwise location stalls at a certain aircraft AOA. We tailor the stall progression to get good handling characteristics. The wing doesn't stall all at one time; it progresses. Even at stall, the wing is still producing a minimum of 80% lift. I need to stop Ask away. @Fly_M20R and @Oscar Avalle, I'm serious about doing some tufting tests if you're up for it.

Repeating. ALWAYS fly the airplane. Stalling is never good. Condolences to family and friends. Hopefully we will find the rest of the story soon enough.

Well put, @Shadrach. The airplane was obviously well outside the operating envelope. The fact that one side of the stabilizer departed the airplane will give the NTSB a lot of information. Data on whether the airplane was rolling may also be available (or reasoned from ADS-B data ... or radar returns). Further up the chain, the elevator departed the stabilizer, which was still attach at that time. Analyzing those parts and how they came apart will also be used. The fact that the elevator was only 600 feet away (and stabilizer 300 feet) says they departed very, very late. Control surfaces will "fly" a long way from where they depart the airplane. They will also go further up the chain. Another point I've heard is about what should have failed first. Remember that ALL airplanes are designed with a MINIMUM safety margin of 50%. Composite airplanes are normally very close to this value (ply schedules are changed to get the lightest structure). Small, GA, aluminum airplanes normally stick with standard material thicknesses. IOW, if an 0.032" skin is marginal (or fails), the designer will go to an 0.040" skin which may give much more than the required 50% margin. We all know that Ralph Harmon designed a really, really beefy airplane! Bottom line: There's A LOT of data the NTSB has to sort through. There's a reason it takes them so long to put out a final report.

Having extra, enhanced, safety equipment installed can change your risk assessment as @aviatoreb so beautifully put it. Any de-/anti- icing system adds a layer of safety but can also add a layer of non-existent armor to your thought process. It depends on how one looks at the risk assessment. I can tell you from experience that no anti- or de-icing system can handle all icing conditions. Declaring yourself #1 at a busy airport is not an enjoyable experience. Flying behind a tanker to learn flight characteristics in icing for the first time is a risk, but a mitigation is being able to fly out of the plume to shed ice. Similarly when we add ice shapes to the leading edge surfaces for the first time ... portions of the span at a time. Something to think about is that the smaller the leading edge radius is, the quicker the surface will collect ice. In other words, if the wing is collecting ice, the propeller, antennas (including COMM) and horizontal stabilizer already have ice. My condolences to all. Fly safe.

TCDS trumps ALL other documents! Of course the documents should agree, but ... One of my first tasks for Mooney-Kerrville with the Fort Worth ACO (while new at Mooney-Chino) was, as a Flight Analyst DER, to make the TCDS, POH and Garmin agree on all the limiting airspeeds. They all need to agree, but ... Great job, @CAV Ice.

Logic and the regulations don't necessarily go hand in hand. This is a problem when multiple STCs, an STC and a Supplement, etc. are added to the same airplane. For example, several Cessnas have wingtip extensions and they also have gross weight increases. Installing both STCs is a bad idea and has never been proven that it is okay. But, the FAA has nothing in place to stop those installations ... until one comes apart in flight. My educated guess is that loss of attitude in FIKI conditions (and probably at night) was considered "catastrophic" (people or the plane will suffer fatal consequences). I suggest calling the factory and talking to Kevin Hawley. He is the Chief Engineer and was the person (from the TKS OEM) that was responsible for the original installation of the TKS system. Because conditions have changed over the years (no vacuum AIs), the Supplement should be revised/amended to either remove that statement/limitation with a note, state why the limitation exists and/or state what needs to be accomplished today to remove that limitation. Regretfully the limitation still exists. It is unreasonable for an IA to know all the interconnections with various other systems are affected by the change they are making. Legally still required ... until paperwork shows otherwise. Court-wise is a totally different animal ... and normally not for the good. Logic ... well ... the jury is more concerned about the best story teller. Call Mooney.

The Wright airplanes were also very aft CG. In fact the 1911 glider went to Kill Devil Hill with two (2) sections aft of the wing, and Orville (along with Alex Ogilvie) added a third aft section. Orville wrote to Wilbur that the glider flew better with the fixed vertical surface out the furthest. Although this surface would have made the glider less directionally stable, the additional weight out front would have helped the longitudinal stability. The bag on a pole out front was merely weight (not the autopilot as told to the reporters). My estimation is the CG was somewhere near the trailing edge of the wing.

@N201MKTurbo This is a perfect introduction to my November "The Mooney Flyer" article on a trip around the weight and balance envelope. The upper left corner of the W&B envelope is cutoff with a diagonal line that runs from the lower left side (starting at the top of forward regardless vertical line) and going up and to the right to the horizontal maximum gross weigh line. This diagonal line is very close to a line for equal tail power. In other words, the tail is producing the same down load along that entire line. As the CG is moved aft or the airplane gross weight is lightened, less tail power will be required. So, to answer the question more directly (but getting somewhat technical), if the ratio of the added weight divided by the aft movement of the CG (slope of the diagonal forward limit line), the airplane will require less tail down load. This is hard to explain, but very easy to see if one plots it on a weight and balance chart. A picture is worth a thousand words Bottom line: yes, it will be more efficient ... better if the weight is already in the airplane. In other words, store oil, tools, etc. in the aft baggage compartment. But there is more to consider ... I am NOT a fan of "Charlie" weights. CG is not just CG for flight characteristics. Mass distribution plays a big role in dynamics. Here's a quick example (also in the article). If one has 400 lbs. of useful load to get to gross weight, adding 400 lbs. at the current CG won't change the airplane dynamics a lot (performance will decrease some, though). Now, if we put that same 400 lbs. in the airplane but distribute it to 300 lbs. in the nose (5' forward of the current CG) and 100 lbs. in the tail (15' aft of the current CG), the CG remains in the same position. BUT, the dynamics of the airplane are completely different! Ask figure a skater. If the airplane were to depart controlled flight, recovery could be in question. Ask the IAC (International Aerobatic Club) guys. Tail weights are highly frowned upon. Last comment (for now ). In cruise, the airplane will loose about 1 knot per 100 lbs. of additional gross weight.

I don't want to be a wet rag on this conversation ... and reignite the topic a year later, but this whole topic is scary to me. Center of Gravity position is not just CG of the airplane. Moments of inertia play a huge part, too, not only in longitudinal and directional stability but departure recovery, too. In other words, if I have 400 lbs. of useful load remaining to get to maximum gross weight, how it is loaded is critical. If I put all 400 lbs. at the current CG, the CG remains the same and the characteristics will change only due to the weight increase. But, if I put 300 lbs. in the nose (5' forward) and 100 lbs. in the tail (15' aft), the CG is still the same, but the inertial characteristics of the airplane will be much, much different! An autopilot will need to fly the airplane a little differently. Recovery from an upset will be a lot different. Look at an ice skater, inertia (spinning) characteristics a much different with ones arms out fully and tucked into their body. I know a couple airplanes that can't certify with small tip tanks. And, technically, doing acrobatics in an Extra with any fuel in the wings is prohibited. Fly safe! -Ron

Way true! But don't overspeed the flaps or gear.

Agree with you, but getting rid of drag is good, too. Rate of Climb is simply excess Hp/Weight. Obviously, weight is what it is, but less of it is better for climb. The more drag one has, the less excess Hp there is for climb. The lift difference between full flaps and half flaps is small as the slot has already opened and the flaps mainly rotate in the last half of travel. Best would be to immediately raise the flaps halfway.

@Shadrach Thank you for teaching me. I am learning, too. CG makes a large difference, too. Most early airplanes (through Ds) have a tendency to be more forward on CG. A recent M20C "client" said that there wasn't enough elevator to flare the airplane ... let alone stall it. The solution was that the pilot wasn't trimming enough. Now the owner LOVES the way the airplane lands ... after nearly 30 years. M20E have a tendency to be aft CG (not sure why with the heavier engine/propeller, and the long bodies are definitely more on the forward side. You've convinced me to write the next "The Mooney Flyer" article to be "A Trip Around the (CG) Envelope." Thanks for the great idea. I always need ideas on what you need to know. In the process of writing the articles, I learn a lot, too! Thanks!

@Shadrach Not disagreeing with you at all. All pilots don't fly (in this case trim) the same way. Neither way is right or wrong. A Mooney (and early Cessna 180/182) have very powerful, trimmable stabilizers. The wing produces more nose down pitching moment at higher AOAs (lower airspeeds) and more yet with flap deployment. The tail must counteract this nose down pitching moment by producing an equal nose up pitching moment. In a Mooney, this can be accomplished one of two ways (or a combination of the two). One way is through trimming (using the horizontal stabilizer). The other way is through pulling back on the yoke (elevator trailing edge up). Moving the trim (stabilizer) results in no pilot force; moving the elevator results in a lot of pilot force. I'll try to put this in perspective with trim and stall. I believe that one of the Mooney production flight test specs is to be able to trim the airplane down to 1.15Vs at the highest forward-regardless CG (top of the left side vertical line on the weight and balance envelope ... lower, left side of the graph). It takes very little elevator to stall the airplane. As the CG of the airplane moves aft (same weight), the airplane will stall just with stabilizer down force ... no elevator required. On the other hand and if we trim the airplane to 1.5Vs (current stall regulation), at forward CG (the sloped line on the upper part of the left side), there may not be enough elevator to stall the airplane (and it would require a lot of pull force on the yoke). What you're saying about the go-around forces are true for you, as .you are not trimming as far into the landing. On the other hand, those who have been taught to always trim away all the forces will have a lot of push force required for a go-around (resulting in many fatalities). Neither operation of the airplane is right or wrong. The pilot just needs to be aware of the situation/configuration. PS. If I disagree with someone here, I will either not reply or ask them a question that will either lead them to my thoughts or they will teach me. I am ALWAYS learning. MSers are great!

We can also require an airplane to have auto-trim, a (no) takeoff system, etc., but now the pilot has to recognize what the airplane and/or its systems are doing versus what a failed system is doing all on its own. I wish it were easy ... it's not.

(c) If marginal conditions exist with regard to required pilot strength, the control forces necessary must be determined by quantitative tests. In no case may the control forces under the conditions specified in paragraphs (a) and (b) of this section exceed those prescribed in the following table: Values in pounds force applied to the relevant control Pitch Roll Yaw (a) For temporary application: Stick----------------------------------------------- 60 30 -------------------------- Wheel (Two hands on rim)---------------- Wheel (One hand on rim)----------------- 75 50 50 25 -------------------------- ------------------------- Rudder Pedal------------------------------------ -------------------------- Wher The outright answer is 50 lbs. This value is to NOT re-trim and to NOT reconfigure the airplane during the go-around. It's the regulation/law. Sometimes the regulations are real world and sometimes they are not. We (ASTM, writing regulatory compliance) are looking at the possibility of lowering these values, but that is very complicated and a BIG deal. Here's a couple examples. Many pilots want an airplane to fly with light controls, but the regulations require the airplane cannot be over-Ged with less than 50 lbs. of control force. That works out to about 13 lbs. per G in pitch force. For multi-engine airplanes at the slow end, Vmc is based on 150 lbs. of rudder force, but can the pilot exert 150 lbs. on the rudder at Vne and not break or lose control of the airplane. Bottom line: It's not that simple. It's hard to design an airplane for the 5% female and the 95% male.

A very tragic event that we can all learn from. Thoughts and prayers to the families. 89% of fatalities in the pattern happen during takeoff and go-around (only 11% on landing ... base to final). This thread has done a good job of pointing to the reasons. On go-around, the forces in Mooney aircraft are high ~40 lbs. (similar to a Cessna). Full power departures are not required in the certification process ... only 75% power is required for this exact reason. Power on stalls are typically tested at 5,000 feet where recovery from a stall/spin/spiral is more probable. P-factor is very high at low airspeed and high power (higher thrust, too). Be safe. Everyone should practice go-arounds ... at altitude first. The first one will have a startle factor.

The elevators (left and right) are and always have been (including the wood empennage) separate control surfaces. They have to be because their hinge lines are not co-linear. As @M20Doc and @1980Mooney have illustrated above, there have to be two push-pull tubes coming from the last idler bellcrank to drive each elevator independently. It is this way on every airplane that I know about that has a swept hinge line. Some airplanes have a swept horizontal surface, but the hinge line is straight and have a single elevator horn on the centerline of the airplane. The Cessna Citation CJ/CJ1 comes to mind.

I think the NTSB is on the right track with the ADS-B data (every second). They will get there ... a year from now.

There can be permanent deformation above 3.8G ... and complete failure at 5.7G ... but it's typically NOT the wing or tail that may fail at those loads. Va will protect the wing (and tail) at gross weight, but it's really there to protect the remainder of the airplane (engine, baggage, seats/occupants, etc.) below gross weight. For example (and using round numbers for easy math ... for me), a 4,000 lbs. gross weight airplane with a 4G limit can fail the wing at 24,000 lbs.(4,000 X 4G X 1.5 safety factor). If the same airplane were flown at 3,000 lbs., The WING could take 8G, but ... The engine, seats/occupants, baggage, etc. (which have not changed weight) are still only designed to handle 4G (plus safety factor). People ask me a lot about angle of attack and assumed to be "minor" changes due to atmospheric conditions (vertical gusts). To put this in perspective, I doubt many pilots would exert enough control force to pull 4Gs (in a Cessna, Mooney or Piper), but the atmosphere (especially in a storm) has no problem taking the angle of attack (AOA) of 4-5 degrees (typical cruise) to stall AOA ... with the applicable G-load change.

As mentioned previously, the Mooney wing is one piece, tip-to-tip. Yes, all the rivets can be removed just like any other wing can be de-rivetted. As is shown in the picture from Don Maxwell of the Mooney "Predator", it is easier to leave the wing attached (with either 6 or 8 small bolts ... I'm not sure how many bolts are in the rear spar attach. There are 4 for the main spar). It is easier this way than to drop the wing straight down ... there are too many systems that need to be removed first, but it is possible. Airplanes like the Bonanza and Pipers are attached at side of body. Those airplanes have a really stout carry-through structure. In those airplanes the wing will break at side of body or the carry-through will break. Beech lost several wings due to improper welding processes on the carry-through. The design was changed early (maybe in the first year of production). If one gets a chance to visit an aviation salvage yard, the Mooney wings will all be maintained as a single piece (maybe with the fuselage section attached as pictured above and maybe not). All the other airplanes will have the right and left wings detached from the fuselage. RVs (Van's Aircraft) have multiple designs on the different models. Some have side of body attachments (easiest but highest stresses at attach points), a carry through where the 2 wings butt together in the middle (carry-through takes all the wing bending loads, and some have spars that extend the width of the fuselage and attach to each other ... like a sailplane. Van is a sailplane pilot, too.