[NSRCA-discussion] Joy of Trim
Nat Penton
natpenton at centurytel.net
Thu Apr 17 19:12:36 AKDT 2008
Chris
Are your incidenses measured relative to the pipe opening ? What is your wing incidence now ? I assume the thrustline is at zero now ? Do you know where the CG is relative to the MAC ? relative to the wing tube ?
The CG needs to be about 35% MAC and LEFT ALONE.
If you put more positive in the wing/thrustline it will go LESS to the gear in knife edge, not more. The spread should be LESS THAN 0.5 deg. It goes to the canopy in the downline because this spread is too much. It goes to the gear in knife edge because the wing/thrustline incidencies are TOO LOW.
The differential needs to be trimmed now - it is independent of the above.
FORGET ABOUT THE STAB FOR NOW.
Follow these directions and get me new mix percentages. nat
----- Original Message -----
From: brian young
To: NSRCA Mailing List
Sent: Thursday, April 17, 2008 8:00 PM
Subject: Re: [NSRCA-discussion] Joy of Trim
No disrespect to Bryan, check with Nat. He has more free time im geussing.
It may be worth heading back to a known setting to double check.
krishlan fitzsimmons <homeremodeling2003 at yahoo.com> wrote:
Ok, back to this again..
Here's what I don't understand with the Triangulation theory.. The theory itself makes sense.. My plane doesn't unless my cg is way back still. It fly's very nose heavy now BTW..
My plane still has the up ele trim in knifes, and still pulls to the canopy in downlines. I went a turn and a half more of positive in the wings and changed the thrust to zero (The thrust I am going to put back to 0.5) the day before the contest.. The mix remained the same, and it didn't help my downlines. But it did neutralize my ele trims from the up it had in it.
Now here's my problem, I am already more nose heavy than where everyone else has it, matter of fact, it's hard to slow it down to land, and it bounces on the gear which it never has before.. Now if I'm correct, my problems show me I need more positive in my wings and a more forward cg according to the triangulation. But if I do that, it will make my stabs go more negative (or down ele trim), which yes, will help my downlines, but won't it make it pull worse to the gear in knife? I already have 1/8 up ele mixed in it in knife. Granted, with an even more forward cg, that should help with the pull to the gear. Am I thinking correct here?
It fly's right now like it's nose heavy and the differential in the roll is horrible..
Thanks
Chris
vicenterc at comcast.net wrote:
Congratulation, you did very good. I don't think you are flying bad after getting that result. California lovely weather. I am tropical guy so I love 90 degrees.
I flew yeserday but it was cold and windy. I could not do any detail trimming in that conditions. I am planing get the incidence at 0.8. Now is 0.6 and it was 0.4. Clearly, the effect of all this was to reduce the mixing. I am around 6% all around which is less than 0.5 degree movement of control surfaces. That is not that bad. The best cg position I have seen is between 0.6 to 1" in front of the front edge of the wing tube. The Abbra tail heavy tracks really bad. I did that test yesterday moving the batteries.
It looks like the negative TL could be the problem. We need to get the TL and the incidence as close as possible. I think within 0.5 degree. I will do this next time and I will let you know. I am traveling this week so hopefully weather permitting I will try to fly next weekend. I think you need to measure were are you in incidence and TL relative to the belly pan floor. In this way we can get equivalent reference.
Thanks,
--
Vicente "Vince" Bortone
-------------- Original message --------------
From: krishlan fitzsimmons <homeremodeling2003 at yahoo.com>
Vicente, SNOW?????????
Holy crap man.. At the Riverside contest today it was over 90.. I am pretty burned.. lol
Did pretty good though, got a 3952 to Rusty Fried's 4000 out of 5 rounds... I'm pretty happy with that for how bad I seem to be fighting the plane..
As for the whole trim thing, well, where we left it last, the Abbra got a little more up thrust (1 washer) and a turn and a half more postive incidence for now as a test. It feels a little nose heavy now. Very bouncy on the gear on landing which it has never been before moving the cg. But the uplines and 45's looked good and felt good. Still has almost the same mixes in knife though. Downlines still pull to canopy. The ele now has neutral trim though..
Just FYI..
Chris
vicenterc at comcast.net wrote:
I wish that were breezy here. Weather has been really bad in Kansas this year. Well, mother nature always wins. We just to need patient, good weather is coming next week or so. Probably, I will have a chance to fly tomorrow afternoon. Today is cold and we are expecting snow.
Have a nice flying weekend,
--
Vicente "Vince" Bortone
-------------- Original message --------------
From: "Derek Koopowitz" <derekkoopowitz at gmail.com>
That is great news, Chad. I'm glad to hear that the issues got resolved.
I'm also very close on my setup... my stab is at 0 and the wings are almost +.5. The plane comes standard without downthrust and I have since added some to help with the pull to the canopy in the upline - its almost 100% but not quite. I think I may still be a little tail heavy and will add some nose weight when I get a day that is calm - it has been a little breezy here. Overall my plane is flying much better now as well.
On Thu, Apr 10, 2008 at 8:56 AM, Chad Northeast <chadnortheast at shaw.ca> wrote:
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 ! ! resul ts !
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 pr! evi! ou s set up
- 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 cl ose
- 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 re! sult :)
C had
> > > 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 ! = facto ry cl! aims 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
! > fo rced 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
> >! > & gt; it a go! and le t 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
> > > > h ttp://lists.n! srca.or g/mailman/listinfo/nsrca-discussion
> > >
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From: "Derek Koopowitz" <derekkoopowitz at gmail.com>
To: chad at f3acanada.org, "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
Subject: Re: [NSRCA-discussion] Joy of Trim
Date: Fri, 11 Apr 2008 23:16:33 +0000
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From: krishlan fitzsimmons <homeremodeling2003 at yahoo.com>
To: NSRCA Mailing List <nsrca-discussion at lists.nsrca.org>
Subject: Re: [NSRCA-discussion] Joy of Trim
Date: Mon, 14 Apr 2008 07:32:52 +0000
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