Re: Is this stalling? Or something else?

From: Nick Ray <lasray_at_gmail.com>
Date: Sat, 24 Feb 2007 20:21:50 -0500

It sounds like your motor stick may not be transitioning ideally. What
may be happening is that the motor stick flexes as it should during
launch and then transitions back to strait after the torque burst.
When this happens the down thrust decreases rapidly while the power is
more constant. Thus the model is pulled into a stall. To fix this,
weaken the motor stick a bit and test fly until you get a smooth
flight.
Just an idea,
Nick

On 2/24/07, Bill Gowen <b.gowen_at_earthlink.net> wrote:
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> 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 - 17:21:58 CET