Blue on Top

The decision altitude(s) for the flight should not be hard numbers ... until the pilot advances the throttles. They vary with WAT conditions (Weight, Altitude Temperature), runway length, wind, available runways, airport surroundings (buildings, roads, open fields), etc. Every takeoff is different. We should also be thinking about this while we're cruising, too. Sailplanes have "rings" on their GPS maps of where it is possible to land ... and they are always "engine out". Plan the flight (including takeoff). Fly the Plan. Oh crap, my Flight Test background is showing its ugly head..

1. As Bob Hoover is quoted, "Fly the airplane as far into the crash as possible" 2. All of these decision points (altitudes) should be made long before the throttle is advanced for takeoff. Airborne decisions take time ... and are often incorrect. Make the decision and stay with it all the way. 3. And the biggest one. Don't stall. Odds of survival go way, way up.

@cliffy I agree with you. 1. Yes, but it will add at least $5K-$10K to each airplane. It will also increase maintenance costs and down time if a system is not functioning. 2. Yes, most older airplanes have natural buffet in most configurations. Most newer airplanes do not. The regulation states that stall warning must come from the same source for all aircraft configurations, weights and CGs. So, if some configuration or CG results in too little or no stall warning, the stall warning must be artificial. 3. Yes, the vast majority of us committee members are "real" with thousands of hours each, both military and civilian. 4. I agree with you on the automation, but fully-autonomous airplanes are coming ... soon. Mooney is/was even looking at it. The part that is humorous to me is that most of the companies looking at this think that they can hand the airplane back to a pilot if something goes wrong. We have already proven the more autonomous a vehicle is, the more the pilot is out of the look and the less the pilot is capable of controlling the vehicle. 5. I, personally, don't believe that training is the answer to the fatal LOC rate. I would venture to say that most if not all of the pilots that are no longer with us passed their last Review and would pass their next one if they were still with us. BTW, the vast majority of LOC fatal accidents are on takeoff, go-around and the moose turn (looking at something on the ground). As you eluted to, we are not getting the pilot's attention soon enough. @EricJ You're correct with respect to redundancy. In this area it is all about the numbers.

Sorry for this blurb, @cliffy, on your topic, but I'll get back to your topic by the end. It's Saturday night, and I'm in a talkative mood Being on the ASTM F44 Committees (Flight, Crew Interface and others), I get to listen to the FAA/EASA/TC/OEM/User/etc. reasoning. It's a seriously hard position and not straightforward as it may seem at times. I am developing a new stall warning system. The Committee is looking at systems that warn the pilot via at least 2 different human sensory paths (ironically, which was assumed by a couple on the Committee to be 2 different sensor paths ... more on that soon). A stick shaker (in most jets - both Part 23 and 25) is both tactile (the control shakes in your hands) and audible (you can hear the control system shaking if your hands are not on the controls ... a requirement for a shaker). Now, it has been brought up that this is a single-point failure. If the motor (shaker) doesn't turn, both tactile and audible warnings will be lost. Almost all Part 23 airplanes have at least one single-point failure mode (Mooney aircraft have the Safe Flight, wing-mounted flip switch, wiring and stall horn). OEMs are scared this is going to have to be made redundant. This will add significant cost. To get back on topic, it has also been brought up about autopilots and if they should be required to turn off at stall warning (leaving the pilot with an out of trim, about to stall airplane) or if they should be required to protect the airplane from ever stalling. The answers aren't easy or straightforward.

Great thinking! My guess is that they may have more internal information and past dealings with their local FAA office(s). I talk to the certification manager at Genesys (STEC) every week. I am often surprised at some of the stories he tells me. It could also be liability insurance. Only guessing.

Almost a perfect wing! Anything over 100% is a weight penalty. Ummmmm ... like a Mooney. Ironically, a metal wing on the 787 would be lighter ... but it would have corrosion. On little airplanes, the 98% would be a weight penalty because the thickness of the failure parts would have to go up to the next standard material thickness ... adding weight. Oh, on the 787 wing a couple years of material were added ... to hundreds.

Great article. Loved it! The mention of 230 HP and the twin didn't become production reality, but this was the beginning of Ralph Harmon's time as Chief Engineer (and his son, too). Btw, Al Mooney turned Hoffman down to metalize the airplane. I would guess the 330 mph is a typo ... and should be 230 mph. I don't know the early M20 Cd, but 330 is probably beyond terminal velocity (weight = thrust = drag ... straight down). The propeller would probably be creating drag at 330 mph. The other airspeed numbers seem reasonable. The climb rate going from 900 fpm to 200 fpm over 10 mph sounds excessive, but just a reminder to FLY THE PUBLISHED SPEEDS!!! (LOL, LOL, LOL) Six (6) G for the wing is not outstanding, either. It had to take 5.7 to certify. I LOVE this stuff!

@cliffy Your background search is fantastic! It's the little details that get projects hung up. This topic has people who are very hard-over (pun NOT intended) on both sides. The problem is that there is a ton of grey area in the middle. NORSEE items are still required to address the system safety analysis. To show compliance with the new regulations, it might be an analysis of amount of good it does times the percentage of time it does it versus what bad things can happen times how often they can happen. If the system is shown to do great good the majority of time, that's a positive. If the same system is shown to be catastrophic in a few cases, that's not so good. For example, if an autopilot is relying on an ADAHRS for input and the pitot or static is lost (or giving it bad data), the attitude and/or altitude will soon be degraded. The autopilot is now following this bad data - with possible catastrophic results. VFR, one is probably okay. IFR, not so much. On an approach, really bad.

@flyer338If you can make an electronic copy of that article, I would love to read it (solutions@blueontop.com). I am definitely NOT questioning you. Interestingly, the Chief Engineer would have been Ralph Harmon. At that time, it would have been common to exceed redline (Vne) by 25 mph for flight characteristics (Vfc) and by 50 mph (Vd or Vdd ... long story) for flutter characteristics. The airplane must be flutter free out to 1.2Vd.

Oops, missed Vno. Vno is defined by the FAA as the maximum structural cruising airspeed. Basically, it is the result of effects on the airplane due to vertical gusts. In other words, vertical gusts will increase (upward gust) and decrease (downward gust) the aircraft angle of attack. At airspeeds below Vno, the airplane will stall before structural damage. At airspeeds above Vno, the airplane can be structurally damaged before it stalls. Since the FAA made the current regulations for gust requirements, many airplane wings are designed for the gust factor which is higher than the maneuvering load factor (3.8G in normal category). On the new M10 the gust load factor was 4.2G, which defined the strength requirement for the wing design.

@RobertGary1 LOL on the gear being allowed to come up through the wing and leak fuel. Although leaking fuel would be a great indication that the spar caps are bent. A Citation V upper spar cap was bent during one of the landing tests that we got too aggressive on. Via sled testing, newer seats are tested to 26G. Many of the US manufacturers will do it here in town at NIAR (National Institute of Aviation Research on the campus of Wichita State University). It's not cheap ... $1M+. These tests are required to meet the HIC (Head Impact Criteria) ... it must be shown that large and small bodies don't hit any structure during a crash.

@ArtVandelayLanding gear loads are typically not an issue for the wing (spar). The airplane is required to take between a 7 feet/second drop up to a 10 fps drop, depending on the aircraft wing loading. This works out to be ~2.7G ... and a carrier landing is 10 fps. So, a "C" will have a lot lower requirement than a new Acclaim. Regretfully, the Mooney rubber donuts don't dissipate much of that load. In airplanes with hydraulic struts, some use an orifice and metering pin to reduce the load going into the wing (if required).

Back into the fire! (I don't think these internal to the post emojis count against me ... although I have over-emojied on Facebook before, too ) WINDSHIELD - If the windshield were to ever come out, it would be pulled away from the airplane. The exception is a bird/drone strike where it will come inward. WHAT FAILS (wing, tail or fuselage) - It depends on the margin of each of these assemblies. There is a 50% safety factor (or more) on all parts to account for manufacturing tolerances, corrosion, fatigue, etc. There may be "margin" above these values because materials don't come in infinite thicknesses (composite structures are design to the 150% safety factor) FLYING SURFACES - These are the wing, horizontal tail surfaces and vertical tail surfaces. Loads imposed on them are proportional to the square of airspeed (Q or dynamic pressure). PEOPLE ON WING - Totally a marketing thing. I believe that Clyde Cessna was the first to do this to show Walter Beech that an internally-braced monoplane could be as strong as a biplane. BTW, Clyde and Walter were good friends. The load on the wing is not only negative Gs, but it is also trivial. Each wing (left and right) take a little less than half the gross weight PER G. So, divide your gross weight by 2, multiply it by maximum, maneuvering G load (3.8), and then add the 50% safety factor. Now you know what the wing will take. ZERO FUEL - Most small, GA airplanes don't have a zero fuel weight (a couple do). Trying to keep this simple, let's say your Mooney has a 1,000 lbs. useful load. We fill the tanks first (600 lbs.) and put the remaining 400 lbs. in the cabin with a couple people and baggage. Fuel actually relieves wing bending loads. In other words, the forces trying to bend a wing would be half the gross weight, minus half the weight of the wing, minus half the fuel weight (i.e. 2600/2 minus 250 minus 300 (or 750 lbs. ... per G)). Now if we fuel for a short trip (100 lbs.) and fill the cabin with people and baggage, it looks a lot different. It becomes 2600/2 minus 250 minus 50 (or 1000 lbs. ... per G). Wing fuel relieves wing bending loads. Vne - Vne is typically determined by several factors with drag and flutter MARGIN being the major players. The airplane must be shown to be free from flutter 20% beyond Vdive which is typically 50 mph/knots beyond Vne). There are several upset maneuvers that must be flown to prove an airplane flown at Vne will not exceed Vdive during these maneuvers. Va - Now for the big one. Va is the airspeed at which SINGLE, full-travel flight control inputs will not break the airplane OR the flight control systems. Think about that really, really long aileron push-pull tube in the leading edge of the wing (I know more than I can say). Why does Va change with weight? It's not the wing or horizontal tail ... it's everything else. Here's a short example. Say we gross at 3,000 lbs. with a 4G limit (I'm making the numbers easier). The wings must lift 12,000 lbs. Now, with the same airplane, we fly at 1,500 lbs. At 4G the wings are only lifting 6,000 lbs. At the lighter weight, we could go to 8Gs to arrive at the same 12,000 lbs. of wing lift. BUT, and here's the kicker, everything else in the airplane still has the 4G limit (and isn't dependent/driven by aerodynamic (airspeed) loads). Let's take a 200 lbs. pilot for example, at 4Gs that's 800 lbs. The seat, attach structure, floor, etc. are designed for 800 lbs. plus a 50% margin for 1,200 lbs. at that location. Now, at the lighter weight, although the wing is good to 8Gs, the pilot seat, attach structure and floor are NOT designed for 1,600 lbs! This is also the case for the engine, engine mount, baggage compartment, etc. Interestingly, I just had a customer explaining a camera installation in a Cessna 310. The whole camera mount (and large hole in the belly of the airplane) were all good. Then he casually, matter-of-factly, mentioned putting 250 lbs. of camera electronics in the baggage compartment. When I asked what the baggage limitation was he stated 150 lbs. They are now rearranging equipment to satisfy that limitation. Hope this helps! And thanks, @carusoam, it's good to be alive

I'm all about simplifying, but getting back on topic. Sometimes the fork in the road isn't a simple, binary operation. Here's an aviation example. Pushing forward on the yoke makes the airplane go down and accelerate. Pulling back on the yoke makes the airplane go up and decelerate ... until it goes down and accelerates. Just sayin'.

If a winglet helps in cruise, it says the airplane doesn't have enough wing ... or has gained too much weight.

We're still negatively buoyant with the chute. Appropriately for this thread, it is drag that keeps the sudden stop at the end from being more than we can handle

Are we there yet, Dad? Dad: We're only 5 pages into a 75 page thread! Slug Bug!

OMG! I am laughing sooooo hard right now! This reminds me of a (now) very funny story that I hope you didn't have to be there to understand. Anyhow, we (the Flight Test crews) had just finished up a long briefing on using our personal parachutes ... and their limitations. Yes, our airplanes had parachutes, too, to return the pointy end to forward when it didn't want to be there. Anyhow, at the end of our long brief, a young FTE asked one last question. Addressing the instructor, the FTE said, "You've spent all this time talking about the first parachute. Are you going to talk about the second parachute, if the parachute streamers or doesn't deploy correctly?" The room went suddenly very, very quiet. Nobody knew what to say. After a few moments, the instructor gained his composure and said, "This is your second ride home. You just bailed out of the first." Great answer.

@Jerry 5TJSo sorry for your loss and for his young family, too. Textron (Cessna) lost a young pilot not long ago ... an ultra-distance runner, nonetheless. We never know. Every day is precious.

Not me, personally, @MooneyMitch. I'm still doing everything I possibly can ... not saying that it's working, but ... As one of Mahatma Ghandi's sayings goes, "Learn as if you will live forever. Live as if you will die tomorrow."

Isn't "negativity" the theme of 2020?

Ironically, it's not as easy to get out of an airplane as you think it might be. Test airplanes for decades had a knotted rope running longitudinally to get the crew from their stations to the exit ... to jump out. Before the Citation X flew, we took the front half of a Citation III fuselage and rotated it vertically down to see how long it would take to bail out. Time ended up being measured in minutes ... not seconds. We totally redesigned with metal foot/hand holds every 6". And, all of this is with the airplane not gyrating like it would be in reality.

We do always have an "out" if the engine quits ... especially new engines. Sadly, I don't understand why people don't know where they are going until AFTER the engine quits, and then they figure it out ... or time/gravity figures it our for them. All y'all need to get a glider rating. You'll learn that in your first couple flights. It's an easy rating. Plus, it counts for a Flight Review! We do get routine training on parachutes (remember, these are not sport parachutes ... it's our backup way home), No firefighting; we run ... or jump! Greco-Roman wrestling comes in handy when trying to get out! (there's more to that story )

Back to negativity. So Textron buying Lycoming didn't help the restart of piston singles at Cessna. It doubled the price of the engines and lowered the reliability ... especially the crankshafts. And a couple test pilots got to be glider pilots. After a good competition, Textron came in and said the new airplanes would have Lycoming engines in them.

The Pre-CAA inspectors are looking at the missing safety cotter pin in one of the elevator hinges. Lucky for all of aviation (just not Lindy), the old guy behind them talks the young officer into a one flight ferry permit