[NSRCA-discussion] Joy of Trim

[Keith Black]

That's very interesting Chad, thanks for sharing it with us.

Keith Black

----- Original Message ----- 
From: "Chad Northeast" <chadnortheast at shaw.ca>
To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
Sent: Thursday, April 10, 2008 10:56 AM
Subject: [NSRCA-discussion] Joy of Trim


> Guys
>
> A while back I posted this, and have recently got around to the 
> suggestions.  Both Bryan and Nat said that the TL was far too much 
> negative as the Twister has -2.5 deg molded into the fuse.  So away I 
> went, here is a copy of the email (just below) I sent to them after my 
> flights to resolve it.
>
> Before last week you could have never convinced me that you could get a 
> plane neutral in knife edge without giving up something....well I 
> officially stand corrected :-)  They know their stuff, were right on the 
> money and the Twister goes pretty much anywhere you point it now without 
> mixing (except a bit on downline but I think I can get rid of that).
>
> I gotta say thanks to Bryan and Nat for their help, they were bang on, and 
> I would suggest to anyone that you give their suggestions and honest try, 
> I bet you are more than happy with the results!
>
> Chad
>
> Hey guys,
>
> Well finally got out flying, good thing too since I am off to NY state
> again on Monday :-(
>
> So, here is where I was, I broke down and bought an inclinometer so I
> could actually measure the plane directly....since I am too lazy to do
> trig.
>
> Engine, as molded is -2.5 but I was at -3.5, wing +0.8, stab +0.1.
>
> So I got as much of the down out of it as possible which leaves me at -1,
> I can't do any more without shimming the motor further out for more
> clearance spinner to nose ring.  I put the wing back to +0.5 and left the
> stab alone.
>
> First flight today, removed the left rudder KE mix I had (had none on
> right rudder), and downline mix.
> - Plane needed a bit of down trim for level, but was pretty close
> - Uplines went to the canopy
> - 45 ups inverted pulled over the top fairly hard
> - 45 downs upright were pretty decent but still dove a bit - recall this
> was my major beef with previous setup
> - knife was pulling to canopy both ways
>
> Second flight - moved CG back as I have felt that it was too far forward
> in general, and I think you would agree if you saw where it was.
> - more down trim
> - Uplines became very close
> - knife both ways was pretty good, really solid with right rudder, and
> very very close on left (slight belly pitch)...probably not worth mixing
> out
> - 45 downs upright were getting better
> - downline mix reduced 2% from start
> - 45 ups inverted better
>
> Third flight - took out 1/2 turn of incidence, which by trig should put me
> at 0.41+ on the wings
> - uplines became perfect, or really close...would need more flights in
> various conditions to nail
> - everything else was really close
>
> Fourth flight - decided to adjust stab since I was carrying a little up
> elevator, so I took 1/2 turn out of adjuster which should being it close
> to 0
> - this pretty much sealed it
> - uplines are as before, very very close
> - no KE mix - even in the KE loop at high deflections its really, really
> good
> - took another 1% out of my downline mix (I am at 2%, started at 5%)
> - 45 ups inverted are really good, just a slight arc over the top
> - 45 down upright is finally straight.
>
> I need to spend some more time on it to really get a good feel, but I
> think the downthrust was causing a lot of problems to this plane.  I have
> never had it in all aspects of flight this close yet.  I am anxious to get
> more time on it and see if the changes really stick.  Unfortunately on
> Sunday this plane is going to a buddy but I plan on incorporating all
> these changes on the new Twister which is why I wanted to get it figured
> out now :)
>
> Any further comments?  CG is probably around 33% of MAC, but to be exact I
> would have to calculate.
>
> Upline snaps are as you say Bryan, on axis with no need to lead....I was
> pretty happy to see that result :)
>
> Chad
>
>
>> > > From: "Chad Northeast" <chadnortheast at shaw.ca>
>> > > To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
>> > > Sent: Monday, March 10, 2008 4:57 PM
>> > > Subject: Re: [NSRCA-discussion] the joy of trim
>> > >
>> > >
>> > > > Ok you trim masters, here is a tricky one for you.
>> > > >
>> > > > Bryan and I have been through this a bit last year but I
>> ran out of
>> > time
>> > > > before the Worlds to fix it and just flew with what I had.
>> > > >
>> > > > On my Twister I have this pesky problem, the setup is like so,
>> > > >
>> > > > wing = 1/2+ Bryans suggestion and I like it
>> > > > stab = 0
>> > > > motor = factory claims 2.5 down, have not measured but
>> could if asked,
>> > I
>> > > > have added more to cure a problem see below
>> > > > CG = has been anywhere from 275 to 300mm from TE mostly
>> with the same
>> > > > result.  Currently its around 285-290 and it feels
>> good at that point.
>> >  45
>> > > > ups inverted track almost hands off if under enough power.
>> > > >
>> > > > Symptoms,
>> > > >
>> > > > Plane flies well, at this setup I need 0 mix right rudder
>> to ele in
>> > knife,
>> > > > and about 2% up ele with left rudder in knife,
>> > > > about 1/32" down elevator with idle to fix a downline
>> > > > Added downthrust as the increase in wing inc. and more
>> forward CG
>> > really
>> > > > helped the mix in knife and made rollers easier, but
>> forced an
>> > increase in
>> > > > downthrust as the plane started pulling to the canopy on
>> uplines.> > > Downline mix remained the same.
>> > > >
>> > > > The big problem I cannot resolve is this, a 45 deg down
>> upright (motor
>> > at
>> > > > idle) the plane pitches to the belly and will not track on
>> its own for
>> > any
>> > > > length of time.  If I switch the idle-down mix off
>> its rock solid on
>> > that
>> > > > line.
>> > > >
>> > > > I am open to all suggestions now that I have a bit of time
>> to play
>> > with
>> > > > this, I hope Bryan chimes in some more as I would like to
>> continue> where
>> > > > we left off last fall.  If you suggest something I
>> will do my best to
>> > give
>> > > > it a go and let you know how it works (provided it doesn't
>> snow!)> > >
>> > > > The plane is basically super locked in with this setup,
>> except for the
>> > > > silly 45 down upright, which is a problem in cubans and such.
>> > > >
>> > > > Comments and thoughts from the masters are most
>> appreciated :)  I
>> > consider
>> > > > myself one of the, cant really trim that well but can fly
>> through it
>> > just
>> > > > fine types :)
>> > > >
>> > > > Chad
>> > > >
>> > > > _______________________________________________
>> > > > NSRCA-discussion mailing list
>> > > > NSRCA-discussion at lists.nsrca.org
>> > > > http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>> > >
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