Re: Is this stalling? Or something else?

From: Bill Gowen <b.gowen_at_earthlink.net>
Date: Sat, 24 Feb 2007 18:17:38 -0500

This is a personal opinion. I think it is a stall caused by moving air. Since we usually trim models to fly on the verge of a stall it doesn't take much to upset them and push them into a stall. Long models will often display this drop in altitude and then continue flying after they stall.

I would be more concerned about what you said in the first paragraph. I would never trim a model's decalage based on what happens at launch. Decalage (again in my opinion) should be trimmed for maximum cruise efficiency. There are other ways to handle launch problems.

  ----- Original Message -----
  From: torqueburner
  To: Indoor_Construction_at_yahoogroups.com
  Sent: Saturday, February 24, 2007 4:38 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



   

[Non-text portions of this message have been removed]
Received on Sat Feb 24 2007 - 15:18:09 CET