[NSRCA-discussion] the joy of trim

[Nat Penton]

Chad
Your  problem is caused by the large difference between T/L and wing. Reduce 
the downthrust by 1 deg and reduce the wing incidence by 1 deg , and test.

We will go from there.

Your excess downthrust requires up elev trim when under power. You need to 
adjust wing and T/L to avoid other problems. If you just lower the wing inc 
it will go to the belly in knife. If you just reduce the D/T it will go to 
the canopy in knife.                                                  Nat

----- Original Message ----- 
From: "Chad Northeast" <chadnortheast at shaw.ca>
To: "NSRCA Mailing List" <nsrca-discussion at lists.f3a.us>
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
>
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