Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Ardy123 on June 01, 2010, 03:13:35 PM
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We have a tool that that will generate flat turn radii but do we have a tool that will for a particular speed give you the vert turn radius? Also, if maybe one could dial in a direction vector and an up vector, (or a quaternion), and it would calculate the turn radius for that position given a speed. Does such tool exist?
Thanks
Ardy
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Whats a vert turn?
If you are turning in anything but a horizontal plane or spiral, radius does not make a lot of sense because the radius is constantly varying do to speed changes.
HiTech
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a Vert turn, is a turn in the vertical plane. Yes I understand that your speed changes, but given an initial starting speed. The reason I ask is because I have noticed that different airplanes have drastically different 'vert turn' shapes, ie some are very round while others are much more egged shaped. Where I'm going with this is, given plane A and plane B where plane B has a worse turn radius, and plane A is turning more or less in the horizontal plain, what is the necessary vertical offset so that plane B can 'cut' the turn by using a more 'vertical' turn.
I have done it in the MA many times by rolling 45 degrees, pulling up,then rolling again 45 degrees and pulling down (a yo-yo like move) but I was interested in knowing the 'exact' 'best' angle as supposed to just what's 'good enough'. It could also be used as a good tool to teach how to use the vertical aspect of flight to newer pilots.
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The math is the same for instantaneous turn radius. Direction doesn't really matter.
Radius is directly related to speed and G force. Since those two variables vary greatly throughout any sustained maneuver the sustained radius becomes a more difficult math problem.
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The math is the same for instantaneous turn radius. Direction doesn't really matter.
But gravity plays a huge part, and can 'tighten' a turn at the top.
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Gravity is part of the G-force used in the calculation. Doesn't change the math
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Gravity is part of the G-force used in the calculation. Doesn't change the math
explain, g force is how many times gravity you are pulling, when you go up and roll using gravity to pull you back down, you aren't pulling many gs at all, its more that gravity is pulling you back down so your turn radius is much tighter.
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Here Ardy this will explain what you want.
(http://332nd.org/dogs/baumer/BBS%20Stuff/TurnPerf/pg214.jpg)
(http://332nd.org/dogs/baumer/BBS%20Stuff/TurnPerf/pg215.jpg)
(http://332nd.org/dogs/baumer/BBS%20Stuff/TurnPerf/pg216.jpg)
(http://332nd.org/dogs/baumer/BBS%20Stuff/TurnPerf/pg217.jpg)
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explain, g force is how many times gravity you are pulling, when you go up and roll using gravity to pull you back down, you aren't pulling many gs at all, its more that gravity is pulling you back down so your turn radius is much tighter.
The one force of gravity is always present. In a perfectly horizontal turn it is not a factor because the radius is perpendicular to the force of gravity. In anything other than a purely horizontal turn the force of gravity must be accounted for.
The pilot always feels the 1 G force. The G meter always reads 1 when the aircraft is sitting still. The one G is always there. It effects the radius of every turn except the purely horizontal turns (which are almost impossible in combat). The always present one gravity force makes every turn bigger or smaller than it would otherwise be.
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There is such a thing as----------> OUTSIDE! :D :D
:salute Ardy :bolt:
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lol... stuck at work now
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Pages 215 and 217 is a good example of why I could never be a pilot. I know ROFL and LOL, but V2/r-cos etc is beyond me.
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We have a tool that that will generate flat turn radii but do we have a tool that will for a particular speed give you the vert turn radius? Also, if maybe one could dial in a direction vector and an up vector, (or a quaternion), and it would calculate the turn radius for that position given a speed. Does such tool exist?
Thanks
Ardy
what is the tool for generating flat turn radii?
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I use Badboys' calculator;
http://bbs.hitechcreations.com/smf/index.php/topic,284578.0.html (http://bbs.hitechcreations.com/smf/index.php/topic,284578.0.html)
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He needs to update the url, it's gone. :(
I use Badboys' calculator;
http://bbs.hitechcreations.com/smf/index.php/topic,284578.0.html (http://bbs.hitechcreations.com/smf/index.php/topic,284578.0.html)
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We have a tool that that will generate flat turn radii but do we have a tool that will for a particular speed give you the vert turn radius? Also, if maybe one could dial in a direction vector and an up vector, (or a quaternion), and it would calculate the turn radius for that position given a speed. Does such tool exist?
Yes such tools exist. It's called a simulator! I'm being very serious of course.
What you're asking for is something to model the interactions in a SUSTAINED vertical turn so that you can predict the performance of an airplane. Even assuming we're talking about a perfect loop meaning no oblique angles involved (lift vector 100% in the plane of the weight vector all through the maneuver) it requires many iterative calculations to solve because key variables are dynamic and changing. In other words your solving differential equations.
In a SUSTAINED LEVEL TURN we don't have to worry about all this and can simplify this because we can assume key variables are fixed/constant, particularly constant velocity, constant g-load, constant lift and weight vector orientation to one another, etc which leads us to use usual level turn radius and turn rate equations not involving nasty PDE's. We don't have these luxuries for sustained vertical turns so there's no easy way to plug a flight test data points into a spreadsheet and crank out a turn rate and radius projections that would be meaningful.
Sure, you could try to simplify it (e.g. plug in 4 sets of data points for instance) but I have no clue how that would be useful or how you could make any meaningful projections from such a procedure.
In short to get the same fidelity in turn rate and turn radius projections that we have for sustained level turns, you have to use numerical methods of solving differential equations to do so which means creating a simulator essentially.
Tango
412th FS Braunco Mustangs
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As an aside, Baumer posted some aero text with the usual "tactical egg" loop shape. That's a very useful diagram to help illustrate the effects of gravity on the loop. There's a really big problem for using that flight path to assist BFM with. The flight path depicted is for airplane travelling at constant airspeed and a constant load factor. How many times in AH do you do that in air combat :) (which is pretty much never)? Take a look at the following diagrams..
(http://thetongsweb.net/images/vert_turn_compare.jpg)
The image on the left is that of our usual tactical egg with an airplane at constant airspeed and constant g-load. The image on the right is the flight path of the same airplane but with constant thrust and load-factor (which again we don't have in our WW2 prop airplanes) which is a much more realistic depiction because airspeed is probably changing throughout the maneuver.
Tango
412th FS Braunco Mustangs
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He needs to update the url, it's gone. :(
Sorry, try this:
Download Badboy's BootStrap Calculator (http://www.leonbadboysmith.com/Files/AH_BootStrap.zip)
Badboy
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That is a great tool! You're the mofo man, man!!! :aok
Sorry, try this:
Download Badboy's BootStrap Calculator (http://www.leonbadboysmith.com/Files/AH_BootStrap.zip)
Badboy