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  1. #1

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    Going forward to Basics: Geometry

    Hey guys, Just thought I'd pick the brains of the collective brains trust on RCG for advice on sharpening my geometry.

    At the last comp it was mentioned too me (amoungst other things) that while some of my geometry was good (verticals were vertical, and circles were circular) but maneuvers like the half clover leaf (we're talking F3A) and the cubans were suffering as my sizing of the circles was dissimilar, and out of alignment.

    Admittely more practice may have sharpened it up, and having someone tell me that is certainly helpful but when i fly alone (and I do a lot) there's no point practicing the wrong things, so the question is, how do you ensure that your manevures show the correct geometry? What training aids have you used to get everything nicely aligned?
    Go knife edge your cub!

  2. #2

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    we've worked out that with a transparent acrilic plastic, where we drew a circle, and some of the typical lines. then you try lets say the avalanche and your caller is seeing the loop thrugh the acrilyc and knows if the shape is going well. good thing is that if you fly alone (ok or lets say with somebody who is not an f3a enthusiast or pilot) he/she can help you with this as it needs no training or knowledge.

    some other things we've practiced is to have somebody at 150 to 175 meters (exactly below the flight depth) with a cellphone and the pilot wiith a hands free device flying and receiving instructions such as "youre going in, or you are too far out" i found this really helpful as it is very difficult to keep depth even making straight passes with no maneuver. i did this with some top pilots in RSA WC and believe me... there is a lot of depth changes "even on the best families"

    And last... i'm waiting for an eagle tree to test.

    But in the end. it is all about practice.

    regards

    Marcelo

  3. #3

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    Mind Flying

    In the past I have made wire frames of circles, verticals and 45s that I have attached to a tripod. I'm guessing this is like the plexiglas method I've heard referred to by AJ and above. I would like to try it with plexiglas with a partner as well as the cellphone/handsfree observer at 150m but haven't done so.

    I don't get a lot of chances to go to the field and practice especially at this time of the year, and it's even rarer I get to fly with other pattern fliers who can help me with my geometry. One thing I have done is at my desk at work - I mark out the lines of the box based on a pilot position right at the edge of my desk in the middle of the computer monitor. At the "ends of the box", a wall on either side about 12' away from the "pilot position", I have taped folded paper at a 45 taped to the wall (at flying height!) to give me an idea of what the 45 looks like at the end of the box. I could add these 45s at intermediate positions but a doorway and other work-related wall-items restrict my freedom to do so.

    Another thing I do, given my restricted stick time is to fly mentally every chance I get, usually when falling asleep at night, or when the rare moment of forced inactivity gives me a chance to mediate. I fly maneuvers and schedules, imagining stick inputs, and add variables such as wind correction, flight direction (r/l - l/r). I also use different planes like maybe a p-51, a Beechcraft Bonanza, or a Twin Commander (Bob Hoover!).

    One addition I have added in the past few days to this imaginary routine is that I fly following a brightly-colored line that I draw in my mind along what I imagine to be a perfectly drawn maneuver geometry against a huge dark pegboard at the imaginary 150m distance, with little black holes in the grid. When it comes time to do a partial loop, I project an imaginary string from the cg of the aircraft that is the length of the desired radius of the partial loop and attach the string to one of the holes in the pegboard at the distance of radius away from the aircraft. I keep the string length constant for each loop/partial loop in any maneuver.

    It really relaxes me and helps me fall asleep. I rarely make it through the sequence (intermediate) before I fall asleep. Also, it's quite hard to make it through several maneuvers without the mind drifting to other things and starting over.

    Who knows what effect this will have on my flying, but the hope is that when I am able to fly with other pilots who can help me with the real-world geometry, I will be better prepared to respond to their observations.astl

    Lastly, I'd like to suggest that the sim developers get on the ball with creating digital versions of the kind of mental imagery described, above, in their sims, for us precision fliers (pattern & IMAC - what a huge market!) to use while practicing. I use Aerofly 5 and there is available on their forum a field with verticals and horizontals at 150m, but this is a mere hint of the possibilities. When I have more time someday to develop my graphic chops, maybe I'll make some additions.

    Bill
    Last edited by n233w; 12-04-2013 at 01:04 PM.

  4. #4

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    I like the idea of a sim with phantom guidelines….including a center line and box edge lines. 45's at the ends and on center, maybe even a straight and level top and bottom line.

  5. #5

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    I got this idea after Dave Stodart told me Jason had done something similar, but last year I started tracing the more geometrically challenging maneuvers in the pattern. I draw a dashed center line on a blank piece of paper and start to draw whichever maneuver I'm working on. To start, I'll use a compass and ruler to make sure the geometry is accurate. I use this version to cement an image in my head of what the maneuver looks like when geometrically perfect, and in addition I'll play with proportions wherever possible to get the maneuver to be as pleasing to the eye as possible. From there I'll start to attempt to draw the maneuver without any instruments as aids. This is the most insightful part of the process; I was amazed at how I made the same mistakes with the pencil as I did with the airplane! It's important to keep your pencil moving as you practice "flying" the maneuver. You can't pause the airplane so don't pause the pencil! As you practice you'll find markers and methods to use to get certain aspects of the maneuver accurate. When do I start that radius? How do I know when to start the maneuver? How do I make sure the second half is the same size as the first half? These are all questions you should be asking yourself through the process. I'll draw a maneuver I'm working on 20 or 30 times trying to iron out my methodology. Once you get out to the field to actually practice you can figure out if the methodology you chose to use translates well to the airplane, and in most cases it does.

    The other thing I've done to help with my geometry is to take out all of the superfluous elements in a maneuver I'm having trouble with. For instance, before the last team trials I took the two integrated rolls out of the Cuban in P-13 because I was having issues with the maneuver. After a flight of just performing the Cuban geometry over and over I realized where I was making my mistake, and it fixed the issues I was having with the rolls as well. Many times a small error in geometry can snowball into all sorts of issues down the line.

    Hope that helps!
    Last edited by bwick; 12-14-2013 at 07:00 PM.
    Brett Wickizer
    Futaba, YS Performance, Central Hobbies, Morgan Fuels
    www.CKAero.net

  6. #6

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    Brett, yeah, and how! I will definetely give that a try!

    Thanks for the input!
    Go knife edge your cub!

  7. #7

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    The attached is a picture (not sure how clear) of what I draw up in CAD.

    I aim for ~4sec/90deg in loooping segment (~ 2sec for a square corner) and travel at an approprite speed to give the desired radius. Faster than ~4sec/90 deg and fitting an integrated full rol into a 90 segment would look forced.

    It's interesting when drawing things up (on paper or CAD) to see just how things fit together and whether flying to the full 1000ft topline (60deg at 150m) is possible and in my old schedule it simply wasn't possible on most maneuveres, but sort of necessary on some.

    The drawing isn't very intuative but the vertical graduation are linear from 150ft baseline to top of the box (60deg up at 150m out) and the horizontal scale is the full 60 deg each side of center at 150m out, with graduations every 15 degrees.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  8. #8

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    Brett - Yes, awesome ideas! Do you use graph paper?

    Bill

    Quote Originally Posted by bwick View Post
    I got this idea after Dave Stodart told me Jason had done something similar, but last year I started tracing the more geometrically challenging maneuvers in the pattern. I draw a dashed center line on a blank piece of paper and start to draw whichever maneuver I'm working on. To start, I'll use a compass and ruler to make sure the geometry is accurate. I use this version to cement an image in my head of what the maneuver looks like when geometrically perfect, and in addition I'll play with proportions wherever possible to get the maneuver to be as pleasing to the eye as possible. From there I'll start to attempt to draw the maneuver without any instruments as aids. This is the most insightful part of the process; I was amazed at how I made the same mistakes with the pencil as I did with the airplane! It's important to keep your pencil moving as you practice "flying" the maneuver. You can't pause the airplane so don't pause the pencil! As you practice you'll find markers and methods to use to get certain aspects of the maneuver accurate. When do I start that radius? How do I know when to start the maneuver? How do I make sure the second half is the same size as the first half? These are all questions you should be asking yourself through the process. I'll draw a maneuver I'm working on 20 or 30 times trying to iron out my methodology. Once you get out to the field to actually practice you can figure out if the methodology you chose to use translates well to the airplane, and in most cases it does.

    The other thing I've done to help with my geometry is to take out all of the superfluous elements in a maneuver I'm having trouble with. For instance, before the last team trials I took the two integrated rolls out of the Cuban in P-13 because I was having issues with the maneuver. After a flight of just performing the Cuban geometry over and over I realized where I was making my mistake, and it fixed the issues I was having with the rolls as well. Many times a small error in geometry can snowball into all sorts of issues down the line.

    Hope that helps!

  9. #9

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    Last night I had another idea: If you have access to a parking lot that is overlooked by a multi-story building, what about drawing some geometry on the pavement and drive an rc car over it? You'd want to be able to look pretty much straight down and mark out the altitude and endpoints of the box...

    Not sure this would help much, but in my music studies I was taught to approach problems from multiple angles and methods so you never know.

    Bill

  10. #10

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    Brett, just curious, what's your reasoning for using 15 graduations for the horizontal?
    Go knife edge your cub!

  11. #11

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    Quote Originally Posted by Rendegade View Post
    Brett, just curious, what's your reasoning for using 15 graduations for the horizontal?
    To gauge how "wide" things should look ie. the big half loops in the turnarounds only occupy the last 15deg at each end of the box for the size I've chosen so I know the half loop must start at 45deg off centre.

    It's not very clear but take the diagram with the cuban eight, it's flown (in the diagram) from left-to-right. Starting at the bottom of the right hand loop (where you finish it as well) It simply can't be any larger, otherwise there can't be a straight line between the end of the cuban and the following half loop. The half loop can't be any larger either otherwise you run out of box, so the cuban followed by a half loop sets your maximum possible top height for the following square loop (top entry). Even with 35m radi (~1.5 sec) you've still only got ~100m long sides (~3sec) if your flying at 150m which is cramped in anyone's language if you need to start fitting point rolls into those legs. Either have to fly much slower or maybe the schedule designers could specify minimum lengths for lines containing certain elements.

    I probably should have graduated the height in degrees as well but the linear scale shows up 1/2 height, 3/4 height and top height scaling better.
    Last edited by bjr_93tz; 12-17-2013 at 05:23 PM.

  12. #12
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    Maybe it would be possible to draw a similar graphic on some kind of logarithmic scale, then adjust the axes to linear and see how the shapes get 'squashed' - sort of the inverse of what's shown above.

    In other words, if you take the picture above and squeeze it so the horizontal spacing is equal, wouldn't it represent what the geometry should look like at the appropriate positioning within the box?. (Example Below)
    Last edited by Jetdesign; 12-17-2013 at 07:21 PM.
    Joe Marri
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  13. #13
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    quick and dirty:Click image for larger version. 

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    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by Jetdesign; 12-17-2013 at 07:18 PM.
    Joe Marri
    Enjoying all things aviation.

  14. #14

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    Thanks gaRDfield, they reckon the 45's at the end of the box are supposed to look like about 60deg.

    To be honest, until they start fitting GPS boxs to the planes and the data is then downloaded and scored by software then we'll just have to keep doing our best at guessing.

  15. #15

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    Yep, that's what I thought, but these days I try not to assume anything
    Go knife edge your cub!


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