Additional thoughs on the NATS Experience

[Don Szczur]

This is what I did an evening before leaving for the NATS. This gentleman, his wife, and sons are from France, of all places, and could speak little english.  They seemed to like Pattern flying when they saw it. I told them to look up Christophe when they get back.
http://webinter.com/rc1
Wind- finals and rolling circles.  There are several factors.  Wednesday afternoon, prior to the finals, the wind was blowing hard from the south.  It was coming straight from behind at about 15. It was most entertaining attempting to keep the stall turn 2 of 8 up from blowing less than 25 meters out. I think I was mentally prepared for the wind blowing this direction for the finals.  My sense is others were also practiced in this wind on Wednesday as well.  Not to be for the finals!  The wind was from the north west!  It was blowing significantly too.  I think it picked up to about 10 to 12 mph, and tapered off to about 5 to 8 for the final round.  I normally cannot even feel wind below 10 if its blowing out, but when its coming in, makes it more interesting after the spin.  Since its a stalled maneuver, the spin brings the plane in, then the 3 of 4 opposite is rushed a bit, then the 2 of 8 up stall turn (another stalled maneuver) forces it in some more.  This is ok- in that it allows the circle to start and end close (and keeping the outside part closer).  I'm all ears in terms of the circle discussions.  It reminds me of a candid camera skit where they hoisted a lady's car and put it down between two walls with just little-to-no room for her to get out.  Back and forth she drove, but there was no way she could get the car turned around to exit the space.  For a rolling circle, suppose the aircraft is moving at 80 mph (but probably more).  But regardless, lets convert that in to meters per second.  Lets see, algebra, yes. if I can remember from my high school track and field days... 80miles/1hour times 1600meters/1 mile times 1 hour/60 minutesx60 seconds.  That comes out to 36 meters per second.  OK if I could do a circumference of a circle, per FAI standards, that is pie times diameter?  I can't remember.  So, we start at our (close in, as we flew at the NATS) 120 meters.  So to keep from getting downgraded per FAI rules, and, lets say we have a highly visible plane- 220 meters at the back of the circle.  So we are looking at a diameter of 100 meters (yes if its flown in, it would be over the runway, with the judges running for cover).  So lets fly it out.  Pie times 100 meters gives a circumference of 314 meters.  Time to accomplish the circle would be 8.7 seconds. That is about 2.1 seconds per quarter.  Now, add in a 12 mph wind.  The wind velocity comes in to play at the tangent points about 7 meters per second.  This slows down the plane as its going into the wind (requiring added throttle to increase the velocity with respect to the wind) and lower throttle on the last quadrant ( to decrease the velocity with respect to the wind) .  So this requires that the circle be done at about quarter throttle average, to allow the (airspeed) adjustments to compensate for the wind.  Do this, just a regular 360 degree turn, at a 50 meter radius (imagine how tight the takeoff procedure turn would be if it was all done before reaching the 150 pole).  Regardless,  I think that a circle done in under 9 seconds would be quite rushed, to say the least.  I did not time mine but I think they came out at least 12 to 18 seconds.  Remember, a standard FAI flight of about 8 minutes averages about 20 to 22 seconds per maneuver. Von used to do tight circles at the TOC.  I tried to emulate that style and got hammered on my scoresheet.  Something about during the circle, at quarter throttle or less, the plane just does not transition from knife edge to inverted and back to upright very smoothly (particularly in wind).  Anyhow, that's my analysis.  For a reference point, at the NATS I moved out the second F05 sequence and got a 997 normalized.  That was with the back of the circle at about 280 meters.  Overall presentation was good on that flight.

Hey, someone tell Mr. Kennedy I'll see him at RCRC tomorrow around 5PM.  See you at the field Bill,

Don
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.f3a.us/pipermail/nsrca-discussion/attachments/20040729/53ed5e8d/attachment.html