Blue on Top

Each airplane is different. None of the Citations have them there for normal operations. The design should have been vetted better in CFD. There are a lot of aero "fixes". Each has it's place where it is most efficient and effective. Some of this is not science; it's still an art … some say black magic

Holy crap! It wasn't even 4:30PM before I became emotionless (out of emotions?) So, one of two things need to happen. Either all y'all quit posting good stuff, or I get out the duct , andtap. Keep 'em comin'! Someone earlier in this thread mentioned going after high dollar items (I apologize for not remembering who). One of the items many have mentioned is the avionics. This is a nail on the head perfect example. The engine is another. Manufacturing techniques is another (including engineering for manufacturing. Systems are another (landing gear comes to mind). I say this not in the Mooney part of it, but spec'ing out the actuator is extremely expensive. Y'all mention the high cost of new airplanes (and I agree with you), and wanting to go back to a "J" or … A "J" with the current luxuries will cost similar to an Ovation. A "J" like the original "J" will be significantly less. OEMs think that everyone wants a Cadillac (which is normally true), but in this case I don't believe it is. Can we design and build a competitive "trainer" that goes fast, too (and still look like a Mooney)? Of course! BTW: Cessna and Piper can't make enough trainers today.

@0TreeLemur I can honestly say that I don't know about the Mooney airfoil. The biggest strange characteristic that I noted during the stall testing on Scott's "J" is that in certain conditions, flow will separate aft of the stall strip AND THEN reattach a foot later. Very strange, but possible with a stall strip that comes in early and very high suction pressures on the forward section of the airfoil. Note: One of the Lear wings has a bunch to hof BLEs in the leading edge (hint). Just for laughs, I'll let you know that: BLEs (Boundary Layer Energizers), LM GeneratorssTs (Little Metal Things), LRTs (Little Rubber Things) and VGs (Vortex Generators) are all the same thing. They all rotate the air to add energy (yes, they all produce drag) to try to keep the flow attached (not separated) to the surface (wing, tail, etc.).

If someone would design a 26G seat for the Mooney (without adding significant weight), they would be multi-millionaires … after they coughed up a $1M+ for the required testing.

Bondo is used on many airplanes to smooth the surface. It is heavy (use sparingly), and it will eventually crack. There was talk at the last MooneyMax that the inboard portion of the wing has a flat spot on the top made during manufacturing. People were talking if they should (and legally can) build that up. I never heard the end result.

1. Define shapes for worst possible icing encounter. Normally accomplished through LEWICE, a CFD icing program. 2. Validate shapes through tanker and/or natural encounters (icing tunnels can help, too). 3. Fly airplane with shapes (real or artificial) to meet all stability and control requirements that have already been shown compliant when the airplane was clean. Easier said than done. Often FIKI is added later on business jets. Sandpaper (40 grit) is used for inadvertent encounters. It simulates a 5-minutes encounter well.

Between internal structure pillowing is normal (it saves weight). This is probably why (educated guess) the wood wing Mooneys are a little faster than the metalized ones (5-7 mph per the rumor mill). It is easier to hide flush rivets the larger the airplane is (actually the thicker the skin is). The Citation CJ-series has beautiful, smooth, aluminum wing skins. So does the Citation X. Skins on that bird are about 1/4" thick at the tip and 1/2" thick at the root. Bondo does wonders … except for weight. Composite structures (depending on the failure design aspects) have rivets, too. They are (not politically correctly) called chicken fasteners. Similar to rib stitching on fabric, they are installed to stop internal delamination/shear crack propagation/poor quality bonding growth.

It doesn't need it (on the tail). Because the tail is designed to never stall (and there is margin). The leading edge radius is large enough to handle the FAA-required ice accretion and still preform all the required maneuvers. It's the little guys that have the problem. Opposite of what one would think, smaller LE radii accrete ice at a much quicker rate. Hint, hint, hint. If you see ice on your (Mooney) wings, there is significantly more on the tail. Bonus Note: Some airplanes have vertical stabilizer de/anti-ice and others don't. Bonus Note 2: Some airfoils are better with ice on them ... drag is always higher and weight is always higher. Some airfoils are very poor with a little ice but good with a lot. Go figure.

PS. There must be a tie between airplanes and bicycles. Thanks, Wright Brothers! PS2. I was beyond a @Yetti at 250 lbs., but now I ride at 175 lbs. Aluminum frame; carbon front fork. I can't afford more, but why anyhow. I'm out there to get a workout. I'm not fast either, but like the Energizer Bunny, I will, keep going and going and going.

I need to be less emotional (or less complimentary) as may be he case. I'm out of those darn emojis again (not in my posts, though I'm not sure that composites are that much smoother (if at all). I had several people at Oshkosh tell me the CJ3 wing was composite. It isn't and never has been. The manufacturing process is cool … but the airplanes are still aluminum. I really, really agree with @PT20J on lowering the costs at this volume. We should borrow from other industries. A couple other notes on composites. If the composite material exists in a known database, the OEM still needs to prove that they can make parts that meet those standards. If the material is not in a database, there is a roughly $2M process of manufacturing and testing to prove the OEM can manufacture better than minimum quality to meet the proposed allowances. Fatigue is also an issue. Yes, composites (typically) have a longer fatigue life. Unlike aluminum, they typically don't tell you before they let go (yes, there are exceptions). This is why all composite airframes have a set life limit. For example, I believe that a Cirrus has to be thrown away at 14,000 hours (yes, Cirrus could extend that life with more testing). As they would saw in Kerrville, "All y'all are awesome ."

Interestingly, the GA(W)-1 airfoil is considered by many to be a very poor GA airfoil (I think mainly due to its high pitching moment. On the other hand, the GA(W)-2 has been much more successful and is on many (certificated and experimental) aircraft. In addition, the GA(W)-2 that is on the NASA X-57 … but modified slightly for blown, high lift flap system. As for true, laminar flow … well … I have been a part of a lot of flight testing. It's all relative. The Citation CJ-series has a very specifically-designed, laminar airfoil. We didn't see a lot of difference, and the FAA made us contaminate the leading edges for FAA-approved certification.

Please don't misunderstand me, NORSEE has some useful purposes … and I hope the new AIs are just one BIG one of them. As has been pointed out by others @gsxrpilot @tmo @0TreeLemur there are misinformation and failure modes of some of these devices that are not directly and obviously intuitive. On a funny note (and all of these are only funny because no one is getting hurt), the first time I got to evaluate a new attitude indicator, it kept red Xing. After hours of frustration and conversations with the OEM, we came to the conclusion that the device had concluded that my pitot tube was icing over … the unit was setting on my desk. Not intuitive.

@John Mininger I will not address company specific instruments. Plus, on this one in particular, I know more background information. For probe-less AOA sensors, the device compares aircraft attitude to flight path (GPS). Please note that flight path is NOT equal and opposite to relative wind as the air itself is moving (turbulence, bumps, up and down movement and plus and minus gusts). Now let's take a quick look at attitude and flight path data. The new attitude indicators use inexpensive accelerometers to measure attitude, but they are made better with other sources and filters (hence the reason G-meters, GPS, pitot and static are added). Through a Kamen filter, attitude is made better. GPS (at best) is delayed 300 ms (0.3 seconds) … but that timing fluctuates. Now, how long does it take the computer to process these inputs, filters, GPS and (if applicable) data busses? Is the GPS data (flight path) being compared to the attitude data at the same point in time? If a product makes you a better pilot, I am for it.

@Cargil48 Not only is this a great thread. There have also been some great posts, too. My answer to the thread topic, "A Full Composite Mooney. Possible or not?" Yes, it is possible. In my opinion it will be heavier and a lot more expensive. Full disclosure, I was the Mooney Chief Engineer on the all carbon fiber M10. We followed that rabbit down the hole. Here are my reasons, many of which have been mentioned previously. Composites are best in pure tension (tensile strength, pulling a piece apart). Most small airplane structure is designed around buckling and minimum thickness materials. For example, nothing will be lighter than aluminum for control surfaces (for just structure). Why? 2 core 2 is the thinnest/lightest composite layup for a certificated airplane. Why? Ths is the minimum buildup that will pass strength, buckling and damage tolerance (hail, hit by a wrench, etc.). To explain that a little more, if one hits the outer surface with something, and it damages the inner surface or core without showing damage on the outside (inspect-able area), it is bad. Aluminum is lighter ... look at a Cirrus (it's aluminum) The highest loaded area of an airplane is the upper spar cap. It is in compression. Carbon (much less for fiberglass) needs to have a copper mesh (something metallic) to disperse HIRF and lightning to the exit (typically somewhere off the empennage). IOW, every part of the airplane has to be electrically bonded to every other part of the airplane. In the case of a flight control, the now heavier surface also needs a much heavier counter balance (normally 3 or 4 times the weight delta of the surface - the counter balance has a smaller arm). Heavier balance weights are bad as they torsionally twist the flight control ... and bad things happen ... ask the Beech 35 people. Changes to tooling (especially prototype tools) are very expensive. Production composite tooling cost is very quantity dependent. Depending on many, many factors, labor costs can be much higher or lower. I got dinged for how many hours the shell takes on the M20 … not my design, though . Yes, no holes to drill/punch, debur or rivet, but I also don't have to build my material (it comes on a roll). It is also dependent on how the tooling is used, how many tools have to be made to meet quantities, if the tools are used only to make parts or if they are also used in assembly, etc. Again, MS is great. I love the discussions. I like the M20 construction, but it's not the lightest. The M20 wing is too heavy (and has too much margin). Remember it was designed by Ralph Harmon that had not too long before had serious problems with the strength of the Bonanza wing and tails. PS. The 787 is not composite for light weight or initial cost; it is composite because it doesn't corrode. PS2. I love, love, love the Al Mooney design article; it is outstanding. Although back then smaller frontal area was associated with lower drag, that's not necessarily true today with current CFD.

I think that would be great!

@Cargil48 With all due respect. Making your airplane all composite would take at least the two children out of the back (it’s heavier), your paint scheme would have to change (composites and high skin temps don’t agree ... ask Beech) and for get the 6-figure price; it’s going to 7-figures. I LOVE your current airplane and paint scheme! It’s a great bird!

All: My intent on MS is to state engineering facts, educate and learn from all of you. If I offend anyone, it is definitely NOT my intent. I've removed my earlier post, and I'll try to restate it better here. To begin, let's delineate NORSEE equipment from certificated systems. Certificated systems (those systems which are required by law to show compliance to the regulations) must be accurate and reliable. Stall warning is a good example. The stall warning on a Mooney is required to be on the airplane and adjusted properly. A NORSEE item is not required by law to be accurate, and (in this case) it cannot replace your certificated stall warning device. Talking only about certificated systems, AOA must be correct because it is used to show compliance to a regulation (stall warning), and in those airplanes with a stick pusher, as a stall barrier (FAA words). In the case of the stick pusher, the stall speed is defined by when the pusher activates. Now we're going to get a little controversial as there is a lot of misinformation being disseminated out there by some very important and knowledgeable people. (again, certificated systems) AOA and airspeed are totally independent of each other, and this is where it gets a little tricky/confusing. For those that have PDFs with airspeed and AOA on vertical tapes on the left side of the display, although they are displayed on the same scale (which happens to he airspeed), they are still independent. In other words, if the airspeed stops (in the valid range), the AOA-driven color bands will still operate properly. If the AOA transducer fails, the airspeed will still be valid. There is so much more to say as an AOA system is complicated, the interaction with other systems makes it more complicated and if there are redundant systems of each of those systems it gets more complicated yet. I really, really hope this helps clarify. I love answering questions. The more people know, the safer we will be.

Actually, everything is getting much, much faster. One can farm out processing, using hundreds of cores if desired. Autonomous VB within Excel can parameterize variables. We once optimized a winglet in less than a day: shape, airfoil thickness, height, sweep, rise, % chord of rise, dihedral angle, etc. Technology is just so way cool. And the next generation will laugh at us on how could we even get anything accomplished with todays current technologies.

There is a great book out there "Illustrated Guide to Aerodynamics" by Hubert "Skip" Smith. I highly recommend it. eBay for $5, including shipping, I'm guessing. As mentioned, rain is a great visualization tool. So is dirt, oil (aero folk use this for flow tests, laminar flow, etc.), yarn/thread tufts, etc. I love to watch vehicles in a light rain (or just with a wet surface. Any movement of the water is visual drag. Similarly, any movement of the air after an airplane has passed is energy that the airplane imparted on the air (drag being a major portion). So way cool.

The optimum airfoil is all in the eye of the designer. Everything in design is a compromise. It would be like asking 100 pilots what is the best airplane? You'll get at least 152 answers. It all depends on your end goals. Airfoils are design tradeoffs of: laminar vs. turbulent boundary layer flow; tolerance to contamination (bugs, dirt, rivet heads, etc.), aft vs. forward loading (pressure distributions); forward, mid or aft camber; ice vs no ice; spar depth (structures); spar placement (structures); flap configuration; flap system mechanism complexity; cruise Cl (and the associated drag); maximum Cl, pitching moment allowed, etc. That is just for the 2D airfoil. Then, add the complexity of 3D … the wing, and one adds: the stall pattern (the 2D stall characteristics have little to nothing to do with how the airplane will stall). What about wing twist (wash out or wash in)? Do we twist geometrically (physically) or aerodynamically (by using a different airfoil root to tip) or both. Taper ratio changes everything. Sweep (or forward sweep in the case of all Mooney surfaces)? Dihedral amount? Low or high wing (and there are A LOT of pros and Cons here)? The list goes on and on. The very, very tip of the iceberg has been exposed .

MS is a great way to use an afternoon. So, ummmmmmm, as politically correctly and non-offensive as I can be (which regretfully is definitely not my strong suit). The original assumption is … ummmmmmmm … flawed. The numbers and calculations are a little flawed, too. Wing loading on a MTOW M20J is a little under 17 lbs./sq. ft. (not 5). Using 5 sq. ft. of area, the "up" load would be 85 lbs. at 1G (not 125). BUT, in reality, there is a pressure distribution on the wing (the highest pressure differential is ~30% chord and very low at the trailing edge. So, long story short, if the aileron pushrod were disconnected in flight, the aileron would float up some but not up vertically. It will float up a little from "trail". Bonus note: your airplane will fly fine with only one aileron … don't try this at home … or the airport. Bottom Line: All flight control system tubes are push-pull tubes. The design/sizing criteria is failure in buckling (compression). If they were always in tension, we'd use a single cable; it's a lot lighter and less expensive.

6) Yes, yes, yes! Inlets in high pressure areas; exits at low pressure areas. 7) Ummmmmm. Yes, round is good with engine cooling inlets/exits (lowest drag shape due to boundary layer and less interference drag). All the new cowlings have round holes up front 8) There need to be less NACA ducts (on the O cowl especially). And a reverse one on the exit - MS needs to consider overly passionate engineers. I'm out of emotion … again Bullet point thoughts for clarification (hopefully) Cowling inlets and exits are designed for worst case (already noted) Cars and airplanes differ greatly in the required aero to cool the engine. Cars (water cooled) need A LOT of radiator surface area/volume and very slow airflow because the temperature delta is low ( ~100F worst case). Airplanes (air cooled) have minimal surface area (cylinder surface areas), a faster air flow is okayish but the temperature delta is high (350F or more). Mass flow into the cowling = mass flow out of the cowling (none gets trapped in there). There is internal duct flow drag for every molecule that enters. Since EVERY condition (other than worst case) supplies too much cooling air through the inlets, the inlets should be designed to dump air efficiently. As I think someone mentioned a while back, closing cowl flaps all the way (and tight with the fuselage) will increase drag. Opening them some will decrease drag slightly ... put a bigger hole in the bottom of your can. There is a pressure box (some have dog houses) on the top of your engine for a good reason. It increases pressure (up to ~ dynamic/airspeed pressure) and slows the air flow down for better cooling (better heat transfer from the cylinder fins to the cooling air). Dang this is cool … ummmmmmm … awesome! -Ron

@Cargil48 And they all said, "AMEN" We all play by the same rules, but cars are a little different. For example they have a "reflective plane" (the aero word for "the road" below them). Aero also plays more with inlet and exit placements with respect to local surface pressures and NACA vs ram air scoops, etc. Ironically down force makes a car go faster (sorry, yes, I have done a little Indy car aero … with a moving floor wind tunnel). This is why they go so fast at Indianapolis … and fatally fast on a NASCAR track.

@PT20J It's mainly area and Fowler motion. Similar to wing aspect ratio, aileron and flap aspect ratios have some effect on efficiency (not a lot), but there are typically other factors that play a bigger role, such as: rear spar location, thickness/shape of the flap, desired stall speed, complexity of the flap mechanism/drive, etc. There are sooooooo many factors that change aileron hinge moments and pilot roll control forces. To start the list: aerodynamic forces, TE thickness and shape (which include centering and flutter considerations), airfoil loading (fore or aft … nothing to do with A/C CG location), system friction, aero balance (where the balance weight is located), aileron gap sealing effectiveness, aileron leading edge shape, control system gearing ratio, control system differential, control system throw (linear or exponential), yoke/stick size, a spade (aerobatic airplanes), control system springs, control system stiffness (Mooney ailerons are poor in this category), control system play, rudder/aileron interconnect, effects of wing bending, etc. If there are enough Mooniacs that want lower roll control forces that can be looked into. Some will result in a HUGE certification issue; some many not have any certification issues. As I wrote that last sentence, what do Mooney pilots think of the rudder/aileron interconnect? (cost, maintenance, flying qualities, etc.). I'm guess that it can be removed … which would make landing in crosswinds easier (lower control forces). Here's an oxymoron for you, I'm an engineer that needs to quit talking so much. All y'all are awesome; only 20 more posts to look at. -Ron

It was a 90/10 split on flaps/aileron span. A spoiler has very little (actually negative) control force. Spoilers need to be held down.