Never glue something that needs routine adjustment.... Perhaps tack-
spot-glue prop blade spars.
WASH: is adjusting, usually during building, wing spar tip panels
away from the flat plane, about 1.5 mm wash-in (up) for most indoor
models at the inboard leading edge. Look at the very end of the
model's flight. The inboard wing panel leading edge is about a
quarter inch higher than the rear spar at the tip. That is wash-in.
The high wash could also be due to a failed or loose glue joint at
the post-wing spar. Wash looks formed on yours, however. Maybe, the
posts are twisted into the sockets - another way to induce wash. I
would also suspect that it may have been formed in to compensate for
the extra initial power of the motor you use. The two wing spars
should be perfectly parallel to have no wash.
In powered flight you want wash-in on the inboard panel during high
torque launch. It increases lift at that panel, prevents the wing
from tucking under and the model from augering into the floor. In
post-launch flight too much acts like too much incidence and causes
stalling. So, level out the wing incidence and wash as much as you
can.
The earlier suggested changes to rubber winding won't change trim,
except to increase duration. Adjustments to the above trim are going
to change the flying characteristics. Now you are affecting,
improving stability. Basically, you are starting over in the
adjustments to improve flight characteristics. And, it's going to be
very hard for me to describe/guide via post. I don't understand the
process that well. The following link goes to a guide session for
basic building and trimming. Check the "No Nonsense Trimming"
section. I will cut off this monologue and go back to it myself. The
rest is more observation for you to consider when adgusting.
http://webs.wichita.edu/scienceolympiad/ws/ws.html
For me, it is easier to build to a straight alignment and trim from
that point. I never want more than 3 - 5 degrees of decalage, the
angle between the wing chord and stab chord. We want some positive
angle, incidence, at the wing but not much, 2 degrees or less. It is
easier to adjust the angle at the stab. Also, mini-stick is more the
hot rod of duration models, so drag becomes more problematic,
especially with its small size. You want as little structure exposed
to the air as possible.
You have a lot of negative stab incidence due to the boom angle. No
adjustable stab post? Three degrees negative incidence is usually the
most ever wanted. I start with 0-degrees incidence in the stab and
almost imediately push the TE up. It's easier to adjust this with a
post and socket at the back, but glued wedges work.
Also, look at the thrust line of the prop. Down thrust at launch does
wonders. I had an A6 drill into ceiling tiles at a 145-foot site in
less than a minute. The thrust bearing was loose. Most duration
models want some down thrust at launch during high torque climb but
little and none during cruise. This is where a flexible (tuned) motor
stick comes in handy.
Since you have an "extended" thrust bearing (it could be 50% closer
to the MS) I would be leary about sanding down the MS a lot. Sorry,
saw this after you posted the photos. The TB causes a lot of leverage
on your stick. Going to a thinner motor if available is a better
idea.
Home made thrust bearings can be a real test of patience to learn how
to make. Any method that provides the third and fourth hand you need
will be a blessing. I speak from an arthritic perspective, however.
Your TB and hook need to be as close to the motor stick as possible
without snagging rubber, maybe a tenth-inch (2.5 – 3 mm); for smaller
section motors.
Time to digest information.
Bruce in Seattle
--- In Indoor_Construction_at_yahoogroups.com, matthew taudevin
<mattnsim_at_...> wrote:
>
> there's a cheetah in the tank?? what does that mean? I never even
considered winding to 90% capacity and then backing off to the torque
required for a no touch ceiling run.
>
> should i glue the front wing post to the fuse and leave the rear
post for trim adjustments?
>
> When you say WASH what does that mean? How do I get rid of it?
>
> and .027 rubber that is .68mm YIKES!! I have some .8mm that I might
try first to see what happens.
>
> How do i get a torque meter? Can I make one?
>
>
Received on Mon Dec 22 2008 - 12:56:07 CET