[NSRCA-discussion] the joy of trimming , left rudder tuck downline pulls

Tue Mar 11 20:17:10 AKDT 2008

If you increase incidence it has the same effect on knife-edge flight as it 
does on level flight, the only difference is that in knife-edge the lift 
component produced by the incidence is now parallel to the ground. Let me go 
back to what I pointed out previously: wing incidence trumps everything. 
Yes, you may end up having a hair of down elevator to cancel out a climb, 
but then again you may also find you can fly slower without having to add 
the down elevator. Then when you roll knife-edge the tuck to belly is gone 
and the rudder is used to maintain level flight. Bryan's reasonings are 
sound even if he may not have looked deeper into why it works... His 
findings are a result of empirical testing rather than classroom theory.

Matt
----- Original Message ----- 
From: "Don Ramsey" <donramsey at gmail.com>
To: "'NSRCA Mailing List'" <nsrca-discussion at lists.nsrca.org>
Sent: Tuesday, March 11, 2008 11:23 AM
Subject: Re: [NSRCA-discussion] the joy of trimming ,left rudder tuck 
downline pulls

> I'm with Jim in not understand the reason some of the incidence changes
> work.  Consider increasing the incidence for adjusting the push to the 
> belly
> in knife edge.  My reasoning would be; increase the incidence, put in some
> down elevator to fly straight and level.  Roll to knife edge and the model
> would then push to the belly more severely.  What am I missing?
>
> Don
>
> -----Original Message-----
> From: nsrca-discussion-bounces at lists.nsrca.org
> [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of James 
> Oddino
> Sent: Tuesday, March 11, 2008 10:59 AM
> To: NSRCA Mailing List
> Subject: Re: [NSRCA-discussion] the joy of trimming , left rudder tuck
> downline pulls
>
> Bryan,
>
> I'm trying to figure out how increasing the wing incidence, I assume
> with respect to the fuselage, will get rid of a pull to the canopy on
> a vertical downline.  Is it because you need to crank in some down
> trim to make it fly level?  Or is it because the tail flies higher in
> level flight and the higher vertical cg creates a couple pushing the
> nose down during the vertical downline?
>
> I assume that if one could achieve a good vertical downline with power
> off, he could then adjust the thrust to get a good vertical upline?
> It would seem that the thrust is part of what made it fly level and
> you would get into an endless loop chasing things around.  What is the
> sequence for getting what you want?
>
> I adjust the relation between the downthrust and wing to get a good
> vertical upline and trim out the pull in the downline like Chad.  Tell
> us how we can get a combination of vertical up with power, level with
> power (less power?) and vertical down without power that are all good
> without throttle to elevator trim.
>
> Jim O
>
>
> On Mar 10, 2008, at 5:31 PM, <shinden1 at cox.net> <shinden1 at cox.net>
> wrote:
>
>> Chad having a small tuck to the belly on left rudder only,,
>>  is always a result in a little too much tail weight  ,,providing
>> the stab halves and elevator halves are correct.
>> thats whats happening in your wandering 4/5`s
>> the tail weight as is ,,is making you add a little down elevator
>> trim because  the wing is flying a little more positive.
>> You want to create the pos angle of attack with the wing only use
>> the tail weight only to adjust the feel for rolls and inverted flight.
>> engine thrust is contributory But ,not doing anything in the left
>> knife edge.
>> it would be happening in the right rudder too.
>> sorry Nat..
>> approach  it like this, before you reset the down thrust ,,,because
>> we want to know what really fixed it
>> increase the wing inc 1/32 "  more positive  or till it stopps
>> pulling in the downline , some airplane require the wing  more than
>> 1/2 deg  depending on weight and airfoils 1/2 pos. is not a hard
>> deck and you will have to move the cg forward to remove the left
>> rudder knife mix ,,move it till you find a sweet spot , between
>> downlines and both knife edges.
>> , Always remember tail heavy makes the elevator and rudder
>> sensitive  and nose wweightmakes them a little numb but  much more
>> effective
>> your spins,snaps entry and exits ,, up and downline,45`s will be
>> corrected
>> you will also see improvement in the wind due to the forward c/g and
>> pos inc. add pos wing inc till it stops pulling to the canopy in the
>> downs
>> and let us know what happens
>> Bryan
>> darn now I have given away the family secrets ,And
>> I have just made it harder to beat Chad <G>
>>
>> ---- Nat Penton <natpenton at centurytel.net> wrote:
>>> 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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>>>>
>>>
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