It's legal to adjust the incidence at the wing if that makes it easier.
To reiterate part of the droop boom philosophy:
I set up all droop boom models to fly with the motorstick level at cruise. A way to do this is to trim the model for a nice cruise and observe the angle of the motorstick compared to horizontal. The adjustment is made by visualizing the wing and stab staying in the same relationship to each other and tilting the motorstick to get it level. In other words, If the model is flying with the motorstick tilted down, you would lower the front of the wing AND raise the rear of the stab while trying to keep the decalage the same. Obviously this will probably require retrimming the cruise.
If you prefer a nose up cruise you can achieve that by the same method. Bernie Hunt thinks that a level motorstick produces the most efficient use of the prop thrust. I think in addition it reduces the drag of the motorstick.
----- Original Message -----
From: ewmonda
To: Indoor_Construction_at_yahoogroups.com
Sent: Friday, November 03, 2006 9:49 AM
Subject: [Indoor_Construction] Re: SO models
Wombat,
The "Little Square" I built has the CG about 3/8" behind the
trailing edge with a 2g motor attached and 1/2" behind the TE
without a motor. It pretty much flew off the board, with the
exception of the tail incidence. I have found it to be very
sensitive to addjustments in the tail, but I suppose that is to be
expected with such a small tail chord (a change of 0.1" on the post
changes the incidence angle a whopping 4 degrees!). Flight times
were about 3:00 and still have a good bit of room for improvement.
Good Luck!
Eric Monda
--- In Indoor_Construction_at_yahoogroups.com, "Bill Gowen"
<b.gowen_at_...> wrote:
>
> The design program shows a static stability margin of 72% with
the CG at 1/8" behind the wing. You shouldn't have to change the CG
but feel free to do whatever it takes.
>
> My personal model has only one flight on it due to factors
beyond my control. That flight was outside at night and was around 2
minutes on an 800 turn wind. If I ever get to fly again (actually
should happen on November 18) I'll report on the results. I have a
wood wing on mine now but will try both wings if I have the time.
>
> ----- Original Message -----
> From: Neil Dennis
> To: Indoor_Construction_at_yahoogroups.com
> Sent: Friday, November 03, 2006 8:32 AM
> Subject: [Indoor_Construction] SO models
>
>
> Wonder, has anyone successfully flown the "little square"
model ? My
> group is having a problem with "tail standing", the one I built
also did
> that. So, what I'm wondering, the stab seems to be too small to
be a
> true lifting stab so the CG can be behind the wing, it doesn't
seem to
> have enough "control". The boys are not happy when the DD Mark
IV's we
> have putt around happily in the windy gym while the LS's fall on
their
> tails and usually break.
>
> Anyhow, I'm going to build another model with the same wing and
stab
> sizes but with the CG at about 50% of chord and see what happens.
>
> Any thoughts, I think the tail volume is much smaller than the
usual
> indoor model that has the CG well behind the wing.
>
> wombat
>
>
>
>
> [Non-text portions of this message have been removed]
>
[Non-text portions of this message have been removed]
Received on Fri Nov 03 2006 - 07:10:08 CET
This archive was generated by Yannick on Sat Dec 14 2019 - 19:13:44 CET