Today's Message Index:
----------------------
1. 06:43 AM - Allegro vortex generators on vertical stabilizer (TIM MOSES)
2. 08:50 AM - Re: Vortex generators update (Hugh)
Message 1
INDEX | Back to Main INDEX |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Allegro vortex generators on vertical stabilizer |
Has anyone tried VG's on the vertical stabilizer to enhance the rudder
stability and thus yaw stability of the plane with feet off the pedals?
Message 2
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Vortex generators update |
Paul:
I have tried to reach Stolspeed at their email address with a few questions.
I keep getting my message returned. Can you give me the proper email address
to use to reach them?
Also from your dissertation on the use of the Feathers VGs, am I correct
that with the VGs on the outboard of the wings only, the landing attitude of
the plane is steeper than without the VGs? The landing attitude of the plane
at touchdown under normal conditions is still fairly steep (in my opinion).
Your statement that with the VGs on the wings only, one could easily drag
the tail on takeoff or landing disturbs me. I certainly don't want to begin
to do this. Please explain this further to me. I am certainly not going to
put something on my plane that causes me to risk dragging the tail!
Hugh
-----Original Message-----
From: owner-allegro-list-server@matronics.com
[mailto:owner-allegro-list-server@matronics.com] On Behalf Of aerosiam
Sent: Tuesday, June 24, 2008 1:21 AM
Subject: Allegro-List: Vortex generators update
To answer Hugh's question in his post titled 'Vortex Generators' Stolspeed
say the VGs can be placed at 8-12% of the chord. I wanted to place them
quite far forward (7%)for the following reasons
The Allegro has a fairly sharp leading egde
Air velocity is probably highest around 7% chord at the stall
The tapered sections are quite narrow (and the most vulnerable to a stall)
and the vortices need time to propagate.
I discussed this with the VG designer and he agreed.
Fitting is simple and the Stolsped instructions are very good. The tapered
section takes a little head-scratching but is actually easy.
You only need to mark 3 points on the wing.
On the constant chord section mark 2 points 2.14 inches back from the
leading edge. The first point (A) is at the wing root, the second (B)
exactly where the chord changes from constant to tapered. Ping a chalk line.
Place the front tips of the VGs touching the chalk line. This puts the
tallest part of the 'fin' at 7%
Now measure the chord at the wingtip fairing join (ignore the fairing
itself) and mark point C at 7% minus 0.8 in (the distance from the front tip
to the fin of the VG.)
Ping a chalk line from point B to C (start of tapered section to the wingtip
- ignoring the fiberglass fairing)
The back of the template must be 90 degrees to the airflow. Mark a series of
lines parallel to the main spar. It's probably easier in removable felt pen
rather than chalk to avoid the dust for adhesion. Use the lines as a
reference for the back of the template.
A couple of notes...
Suggest you try only the tapered section first then full span if you want.
If you are going to do stall tests with and without VGs, are you current and
familiar with stall recovery? I flew with a chief instructor which was a
comfortable feeling! Did you get your stall warning working?
Talked to the Italian dealer who said the Allegro will recover from a spin
normally and immediately with full opposite rudder. After 3 turns
autorotation speed increases.
See http://www.mcp.com.au/allegro/flight-test/flight-test.html about sharp
stall and wing drop power on
See http://www.aero-siam.com/page143.html for VG flight report and pictures
of VGs
Suggest you fit the horiz stab VGs and test fly before fitting the wing VGs
Aircraft will take off sooner and land and float a little later. Touchdown
31 kts CAS in ground effect.
Easier to bump the tail (and take off too soon) because the nose angle is
higher for a given stick input.
I have a dynon pitot set several degrees below incidence. The factory pitot
does not seem to suffer position error.
I will check measurements when I am next at the field.
Regards
Paul
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=189510#189510
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|