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Blue on Top

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Everything posted by Blue on Top

  1. Blue on Top
    1) I have no intent to raise prices, costs, complexity, weight or space. When you get to know me, you'll find out I am all about simple, inexpensive but real-world effectiveness. 2) You MAY also have (some models do) an airspeed switch to stop the pilot from raising the gear while on the ground. 3) If everything is mechanical, great! Several people have commented that their flap position indicator hasn't worked in years. I truly love an all mechanical airplane: flaps, gear, etc. If the airplane is all mechanical, it's probably not a good choice to add electronics. 4) I am looking for safety enhancing equipment (yes, NORSEE in some cases) to save lives. I'm tired of losing friends. One or two oversights shouldn't cost lives. 5) @Hank I appreciate your sarcasm. I'm working hard to get rid of mine. It causes me issues (friends of mine that are reading this thread are laughing their buns off right now), but I understand where you are coming from.
  2. Blue on Top
    PS. The rudder-aileron interconnect system would most likely not be certificable today because of a single spring breaking causing a problem (unless it can be proven minor) … especially with the hook ends on the springs … they fatigue and break off.
  3. Blue on Top
    @takair According to Craig, I have forever deleted it. Thanks for the great admin work, Craig. Thanks for the repost. I'll re-read it again to see if I can glean more on the topic. 50 lbs. of rudder force for a standard rate turn sounds like a lot to me, but … If you hold neutral aileron and apply rudder it should sssssslllllloooooowwwwwwlllllyyyyy induce a roll (as you mentioned. The rudder will initially roll the airplane the opposite direction (it too is an aileron). After the airplane is yawed, the dihedral effect (yaw-roll coupling) will take over and start to roll the airplane. This is exactly the lateral-directional test/regulation that was added by 23.177. As you mentioned, the interconnect system (shown in the illustration) is 3 different parts (pushrod (24), bellcrank (20) and 2 springs (23) - only one shown for illustration clarity) plus the attachment hardware: 21, 22 (2), 25 and 26. (15) is the aileron push-pull tube. Gurney tab or "T"-strip? This would make sense for the light rudder loads. Adding the centering bungee would then reduce drag (but increase part count and complexity I'll search for pencil holder It looks like the aileron rudder interconnect is still in the "J", but I don't see the centering bungee … maybe speeds had gone up enough by then.
  4. Blue on Top
    Digging through the parts manual for the 65-67 C-F models, it shows an interconnect (not exactly sure how it works, but have an educated guess). It's a one-direction, tension spring that looks like the distance gets longer in both directions of rudder or aileron travel. This also implies that the interconnect does very little to nothing around neutral of either surface. All models and all years in this manual have these parts. So the change would be before C-2807, D-0252, E-0470 and F-all. I will need a parts manual for airplanes before 1964 to go further. It's also interesting to note that all these airplanes also have a rudder centering bungee up near the pedals. It's an odd place to put one, but the rudder control system is all push-pull tubes.
  5. Blue on Top
    @Hank Takeoff warning systems use speed, landing gear position, WOW switches and throttle positions to determine that the airplane is not flying and on the ground. Flap position, speed brake position, etc. are looked at and then sound the warning when the throttle advances past X position. We all miss items on the checklists.
  6. Blue on Top
    @MooneyMitch I am guessing fairly early (but I've deleted the information in the previous thread … hint to who posted the link before (and my apologies). If anyone has the IPC, it would definitely have serial numbers in there. If someone can send me an IPC, I can look it up quickly and post it here. Remember that serial numbers were different with different owners of "Mooney". One of the owners made it really ugly when they used YY-#### for all 4 of the models made during that time. So, during those years, there were 4 identical serial numbers of each model produced … you have to know if it's a C, D, E or F as it wasn't part of the serial number (which it is today). Hope this helps. -Ron
  7. Blue on Top
    I believe that one of the Cirrus training programs is required by at least one of the insurers to even get an insurance policy.
  8. Blue on Top
    MSers: I inadvertently deleted the earlier thread. ALL the previous information was fantastic! I'll try to pickup where we left off … with what I thought I was going to delete (not the thread Between the B and C, rudder travel was changed from 18 +/-1 to 23 +1/-0 because the amount of (cross control) rudder travel required for crosswind landings was considered to be not enough. Aileron travel was not changed. This larger rudder travel still exists on new airplanes (so all the later short, mid and long bodies). The irony in this is that a rudder-aileron interconnect was added mid C (not at the beginning of the C models). It was stated that the interconnect was added for better lateral-directional stability. Although this would be true, it also stated that it was only effective for the higher rudder deflections. Using experience, it is possible that the rudder forces are light (and lighter more as travel is increased) and the rudder could hang when out that far (and cross controlled). Just a thought, but the interconnect would bring it back. In addition, the interconnect increases the forces required for crosswind landings. Let's get this party started … again. -Ron
  9. Blue on Top
    I’ve heard rumors, but are pilots routinely getting a stall warning on takeoff? If so, this needs to be fixed. Is it only during a full flaps takeoff? These accident scenarios mentioned above are the #1 cause of fatal accidents. Period. The base to final turn accounts for only 5%.
  10. Blue on Top
    I am guessing that there is not a takeoff warning if trims are not in the correct position, flaps are not in the correct position, etc.
  11. Blue on Top
    Wow, I love how all y'all are going after the wives tales. Sorry for the delay, I had to go through all the other thread, too (love this stuff). @PT20J Skip, no it is not common for an airplane to enter a stabilized spiral and stay there. There are so many factors that influence that flight characteristic: (aircraft specific) rigging, control surface shape (or bent), wing shape (or bent/twisted), fuel imbalance (and total amount), etc. The Cessna singles have very, very, very high spiral stability. IOW, the airplane has to be forcibly controlled to Dutch roll (the opposite mode from the spiral mode). As for recovering from a VFR into IMC situation, use your instruments to tell you what is going on. Note: Most gliders (that are not used in IFR operation) don't have attitude indicators. The odds of losing those instruments at the same time are very, very low … that is with a 6-pack. For those reading this thread that have glass panels and no round dial backups. Get to know the failure modes of your instruments! For example, know that with the new electric AIs, a loss of pitot, static, GPS, etc. will degrade your AI. Know what happens with the loss of any accelerometer. IOW, failure modes of the electronic versions of the round dials are not the same as failures of the round dials. As an example for certification today, loss of attitude is considered catastrophic (assumed electronic). Everyone (until recently) had to fly home partial panel. That is one advantage of the 6-pack.
  12. Blue on Top
    First of all, you guys are awesome! I would love to know your results. Smooth is always better. Molecular level … I'd have to think about that. I know that paint won't stick … it doesn't have anything to grab. Laminar flow is a totally different beast and depends more on pressure distributions on the wing surface. Laminar flow is encouraged by the shape of the airfoil and by continuing to have a negative pressure gradient further aft on the airfoil (which is why laminar flow airfoils are thicker further aft). The drawback (getting to your smoothness point) is that only the air layer attached to the surface cares about surface roughness. The remainder (as one goes up off the surface is air-to-air friction (layers or turbulence - laminar or turbulent boundary layer). So, even if the surface is perfectly smooth, dents, dimples, dips, steps (forward and aft facing), bugs, roughness, etc. will trip the flow to turbulent. Aerodynamicists call this the transition point. The advantage of laminar flow is that the boundary layer is thinner. And this is an area where I think it is easier to think of the wing cutting through the air as opposed to a wind tunnel where the air flows over the wing (yes, they are both the same … it's just a frame of reference). With a laminar boundary layer (which is physically thinner), less air is being dragged along with the airplane; therefore producing less drag.
  13. Blue on Top
    Skip @PT20J Yes, all airplanes have longitudinal short period and long period (phugoid) oscillations. What may be different between airplanes is how much they are damped. For example, the short periods have to be heavily damped (there is an FAA definition for that), but they also might be deadbeat (they return to the initial condition without any oscillation. The phugoid on the other hand is only noted in certification as to not cause undue pilot workload. I'd have to look at the regulations to know the exact wording. Trim bungees will only effect longitudinal characteristics. My guess is that the aileron-rudder interconnect doesn't change the spiral stability of the airplane because the interconnect doesn't move if either of the control surfaces don't move. Spiral stability is the opposite of Dutch roll stability. Typically, light GA airplanes will have a negative spiral stability. The contrary would be a continual Dutch roll oscillation … which would get annoying. The is why most larger airplanes have yaw dampers.
  14. Blue on Top
    Skip @PT20J The gear has excited the longitudinal long period (phugoid) mode. There are two longitudinal, oscillatory modes in aircraft. A short period (<2 seconds) has to be heavily damped, and a long period (phugoid) has to be controllable. From your great graph, it looks like it has a 14-15 second period. Very controllable. Interesting to note is the large amplitude of pitch change (+/- 10 degrees, initially). Ironically, the oscillation (entire maneuver) is all at a constant AOA. During this maneuver, the airplane is trading altitude and airspeed … all at the same AOA. Cool data!
  15. Blue on Top
    @Cruiser Oh, how I want to make your day. Your boat not only has fluid dynamics just like an airplane (air also acts like a fluid), your boat is simulating supersonic aerodynamics! The density of water is much, much greater than >>> air. Your boat's bow wave simulates a supersonic shock wave in air. We use it on water tables as a 2D version of the airplane 3D shock cone, and in water tunnels, too. Yes, the fast moving stream of air causes a lower pressure area around it. It draws the higher pressure air (not thicker, but …) around it into the stream … pulling the paper towels up to it. Now, because the paper towels are experiencing flow across them, drag is produced, pulling them off the roll. Walla! For some harmless fun … unless they catch you. Get your leaf blower, a paint roller handle, a little duct tape and rolls of toilet paper from Sam's Club or Costco (your preference). Then Google "toilet paper shooter". How do you think one can TP a house in moments … and drive away before they can get to the door? Mother Nature is a simple lady. Modeling her characteristics on the other hand is VERY complicated. Having it visualized (tufts, oil flows, paper towels, rain, etc.) is priceless. Blue on Top, Ron PS. Yes, I spent my childhood leaning over the bows of boats (all kinds) and playing billiards. How else is a child to learn aerodynamics and physics?
  16. Blue on Top
    @PT20J Skip: Tough to say and even tougher to analyze, so here's my best guesses … (and everything you have said is correct and should pitch the nose down) 1) Could have something to do with the nose bay opening. The nose gear also destabilizes the airplane a little in directional stability. The nose gear doors/bay may be giving a little lift. 2) (Don't shoot me here -it's happened before with very qualified test pilots, but …) Are you doing this with your hands off the yoke?
  17. Blue on Top
    Continuing on that thread, opening the storm window should be in your POH for cabin smoke evacuation.
  18. Blue on Top
    @Cruiser LOL! OMG, this is funny. It's Bernoulli. You described it well. The stream of air coming into the cabin has a lower static pressure (higher dynamic pressure). The towels are being sucked up into the side of the stream of air which has lower than ambient static pressure. The roll of paper towels will unroll when the drag on the exposed towels creates enough torque to unroll the paper towels off the spindle.
  19. Blue on Top
    Skip @PT20J, Ironically, it is a Mooney question; the M10 POC has split flaps. A split flap is very similar in lift delta to a simple flap. Data in "The Theory of Wing Sections" is almost all for split flaps. Another characteristic is higher drag, which can be good or bad - depending if the designer wants and/or needs the drag. It still meets the Kutta condition. An advantage is that the upper surface remains attached at all flap deflections. With a normal flap, the upper surface separates between roughly 25 and 35 degrees (airfoil dependent). The bottom surface (actual split flap portion) is the same. Oh, the split flap on the Cessna 190/195 is to lower the pitch attitude … so the pilot can see over the nose on landing … 1 mph stall speed delta.
  20. Blue on Top
    @0TreeLemur The main point I wanted to make is that lift doesn't go to zero past the stall angle of attack. I would also say that the current military fighters (F-16, F-18, etc.) use vortex lift. In those cases, I would definitely call the wing "stalled" by the classical definition. It is producing lift but not enough to support the airplane at 1G. In addition, the small angle theory used to develop most of the aero equations goes out the window (and with thrust producing "lift"). But you know this. Merry Christmas and Happy Holidays.
  21. Blue on Top
    I totally agree with all, except that 12(c) is not producing lift (may be a definition thing). Even above stall AOA, wings (even symmetrical airfoils) produce lift (force perpendicular to the relative wind) until near an AOA of 180 degrees. An airplane with a wing in a similar condition to 12(c) will produce ~0.80 G (Nz-stab ~= 0.80). Great post!
  22. Blue on Top
    @PT20J Great article. Manufacturing is definitely easier with a constant chord. Roll rate is not as good (not mentioned). Dead weight is heavier than the article eludes to. Wonderful article..
  23. Blue on Top
    A PA28 wing is not rotating … nor are any other airplanes wings (since the early 30s). So, yes, dimpling an airplane wing will not reduce drag. On the other hand … A golf ball (or baseball or tennis ball or soccer ball, etc.) uses rotation to curve the flight path and reduce drag. Due to a turbulent boundary layer and rotation of the golf ball, the flight path will change due to rotation. For example with a duffer like me, if I top the ball, the ball will initially rise due to slope of the club face at impact. Because I hit the top of the ball, it will rotate top down at the front. Adding the velocity vectors, the top of the ball will have the velocity of the ball minus the velocity due to rotation, and the bottom will have the velocity of the ball plus the velocity due to rotation. As a result, the velocity on the top is lower than the velocity on the bottom. As a direct result (Bernoulli), the static pressure is higher on the top than the bottom, and the flight path of the ball curves dramatically downward. This is the same for slices, hooks and skys … just rotation in different axes. Note: Analyzing the aerodynamics of a golf ball while playing a round will not help your game (yes, personal experience). As for drag, the air on the backside of the ball is trying to stay attached. The dimples help make a clean separation from the ball. Remember that the static pressure is low on the backside … creating drag.
  24. Blue on Top
    1. Less drag (good) 2. Easier to get the boundary layer to separate on the backside (good - less drag) 3. Forms a thicker, turbulent, boundary layer quicker (stops laminar flow earlier) so the ball flight can be tailored more by spin.
  25. Blue on Top
    We have voiced all of our opinions, but no one has changed their minds … typical pilot conversation (I am one, too). BUT ... 1. We have good CFD models that predict lift, drag and pitching moment well … most of the time. We pay good aerodynamicists to know when the CFD is right or wrong. These CFD programs also include boundary layer (and millions of panels or nodes). Typically, the equations involve full Navier-Stokes equations, which include Bernoulli and Newton. 2. If you believe a typical Mooney wing has laminar flow further aft than other airplanes, I have ocean-front property for you in Arizona. Sorry. Please note that there are basically 3 types of boundary layer flow (boundary layer is the flow close to the surface and measured perpendicular to the surface until the flow velocity becomes free stream. It starts at 0" thickness at the stagnation point and grows until it is ~1/2" thick at the trailing edge. 3. The SAME airfoil cross section will perform differently at different Reynold numbers. This is an area that separates the engineers from the pilots (innuendo intentional). If the root chord is 72" and the tip chord is 36", the tip airfoil will stall first (the Rn of the root is 2X the tip). If an airplane is flying at a higher speed and/or higher altitude, it will stall at a higher AOA because the Rn is hgher. The Cd of a Pilates ball (smooth, large diameter) is lower than a ping pong ball (smooth small diameter because the Rn is higher on the big ball. This is why smaller, round antenna produce more drag than a larger, streamlined antenna. 4. A golf ball is dimpled because … okay, I've gone to far.
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