[NSRCA-discussion] Joy of Trim

vicenterc at comcast.net vicenterc at comcast.net
Thu Apr 10 08:44:21 AKDT 2008 

I believe that the Abbra has the same problem.  As I said before, my electric version had similar negative TL.  I adjusted to be close to zero.  I flew fist time last weekend.  That was my first fly this year.  I really have so many trim problems in my fingers and brain that I can not give good results in trimming the plane.  Also, it was very windy but it is clear that the results are similar to your results.  I will try to fly this weekend if weather cooperates.  I will report more details as soon as I have chance.

Right now I am here:  wings +0.8, stab -0.5, TL -0.5.  I will try to get the TL closer to 0 before flying this weekend.  

--
Vicente "Vince" Bortone

-------------- Original message -------------- 
From: Chad Northeast <chadnortheast at shaw.ca> 

> 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" 
> > > > To: "NSRCA Mailing List" 
> > > > 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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