Re: Is this stalling? Or something else?

From: <RLBailey_at_care4free.net>
Date: Mon, 26 Feb 2007 11:09:41 -0000

There is an extra cause which I have found via F1L and F1D; namely that the CG is a bit too far back. A few mm makes the world of difference. It was my undoing at Slanic in 04 when I did worse than in 02. The models were not sufficiently stable and the stopwatch told the story! In the case of F1D, a symptom is the prop rpm cycling up and down during cruise.

Bob

----- Original Message -----
  From: torqueburner
  To: Indoor_Construction_at_yahoogroups.com
  Sent: Saturday, February 24, 2007 9:38 PM
  Subject: [Indoor_Construction] Is this stalling? Or something else?


  I have had experience with a motorstick bending in the vertical plane. You trim the plane to
  fly well at launch, but it stalls, stalls, stalls as the torque, and therefore the bend, decreases
  over the length of the flight.

  However, something else I have sometimes observed is similar to, but subtly different that
  the behavior described above. The climb and cruise are normal, but as the plane is
  descending it kind of hesitates - almost as if it has just turned into a headwind. As a result,
  it drops down a foot or two, nearly vertically, then resumes flying normally. Sometimes this
  happens only once during the flight, somes two or three times.

  Looking back to our SO biplanes last year, they seemed more prone to this behavior than our
  monoplanes, but perhaps this is just coincidence.

  Any ideas as to what could cause this? It is under discussion on the Science Olympiad
  Student Center message board. One post mentioned stab tilt, or perhaps excessive stab tilt
  as the reason, but I don't see how it could be connected to this phenomenon.

  Dave Drummer



   

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Received on Mon Feb 26 2007 - 03:49:14 CET