[NSRCA-discussion] Another trimming question

Wed Oct 25 18:35:18 AKDT 2006

Ed
The way you describe the problem with turbulence,  CG change will not be of 
any benefit. The parameter that counts most is taper. Going from a .6 tip to 
a .38 tip moves the panel center of lift in only 10%, but where it counts 
bigtime is in reducing area near the extremities. You will also like the 
lower moments of inertia - the feel.

Sweep will cause problems in turbulence, but I don't recall any of Hansen's 
designs having much sweep. I prefer to limit the sweep to 3degrees. Sweep is 
measured by the line thru the ACs of the airfoils, the 25% chordline.
                                                   Nat
----- Original Message ----- 
From: "Ed Miller" <edbon85 at charter.net>
To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
Sent: Wednesday, October 25, 2006 4:29 PM
Subject: Re: [NSRCA-discussion] Another trimming question

>I fly my EMC2 with a fairly forward CG and it too becomes a bit of a 
>handful
> in heavy wind.  Turbulence seems to be constantly rocking the wings. 
> Being
> under the 1lb per 100square rule ( 1100 squares at 10lbs 7 ounces ) I
> believe has something to do with it also.  I'm going to push the CG a bit
> more forward to see if there is any improvement.
> Ed M.
> ----- Original Message ----- 
> From: "Dean Pappas" <d.pappas at kodeos.com>
> To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
> Sent: Wednesday, October 25, 2006 2:49 PM
> Subject: Re: [NSRCA-discussion] Another trimming question
>
>
>> Hello Peter,
>> Fred and Anthony are onto the basic issue. You will almost certainly have
>> to trade off the "rolling workload" versus damping in turbulence, using 
>> CG
>> position. Many flyers trim themselves into borderline tail-heaviness in
>> order to lessen the workload in rolls, but the piper will be paid. I
>> always liked them nose-heavy, myself. I figure predictability is more
>> important.
>>
>> I don't know the Impact, personally ... does it generally handle
>> turbulence well? Some designs don't.
>>
>> good luck,
>> Dean Pappas
>>
>> -----Original Message----- 
>> From: nsrca-discussion-bounces at lists.nsrca.org on behalf of Fred Huber
>> Sent: Wed 10/25/2006 2:24 PM
>> To: NSRCA Mailing List
>> Cc:
>> Subject: Re: [NSRCA-discussion] Another trimming question
>>
>>
>>
>> Moving CG forward and adding + wing incidence should help upright wind
>> penetration... but inverted would then need more elevator correction to
>> prevent the nose from dropping, and the plane might have pitch with 
>> rudder
>> and other effects.
>>
>> Typicly I approach trimming from a nose-heavy start. and I do notice the
>> plane being affected more by turbulence as the plane becomes better
>> trimmed
>> and the CG approaches the point where little or no elevator is needed for
>> inverted flight.
>>
>> I suggest more expo for softer stick centers, allowing correcting for the
>> wind effects with less "jumping" of the model.  If the plane flys the way
>> you want when there's no wind... Leave the CG, incidences and the rest of
>> the setup alone.
>>
>> If just adding expo and a little airspeed does the trick.... its the best
>> solution, as it has the least chance of negative side effects.
>>
>> FHH
>> ----- Original Message -----
>> From: "Anthony Romano" <anthonyr105 at hotmail.com>
>> To: <nsrca-discussion at lists.nsrca.org>
>> Sent: Wednesday, October 25, 2006 9:30 AM
>> Subject: Re: [NSRCA-discussion] Another trimming question
>>
>>
>> >
>> > Interesting thinking a little more positive would allow a further
>> > forward
>> > CG
>> > which may  give you a little more stability. Document it so you can 
>> > move
>> > back and give it a try. As I have heard said "trimming is a verb."
>> >
>> > Anthony
>> >
>> >>From: "Peter Pennisi" <pentagon.systems at bigpond.com>
>> >>Reply-To: NSRCA Mailing List <nsrca-discussion at lists.nsrca.org>
>> >>To: "'NSRCA Mailing List'" <nsrca-discussion at lists.nsrca.org>
>> >>Subject: [NSRCA-discussion] Another trimming question
>> >>Date: Wed, 25 Oct 2006 08:37:54 +1000
>> >>
>> >>Hi Guys,
>> >>
>> >>
>> >>
>> >>I am looking for opinions.
>> >>
>> >>
>> >>
>> >>I am currently flying the COMP-ARF IMPACT with DZ160 which I am very
>> >>pleased
>> >>with.
>> >>
>> >>
>> >>
>> >>Model is flying with no trim and negligible mix. There is no rudder to
>> >>elevator mix for knife edge flight and 5% mix at large rudder throws 
>> >>for
>> >>rollers etc.
>> >>
>> >>
>> >>
>> >>Model climbs as straight as an arrow so I am happy with my thrust
>> >>settings
>> >>and the model pulls ever so slightly to canopy on long down lines which
>> >>is
>> >>mixed with throttle.
>> >>
>> >>
>> >>
>> >>The incidence settings are 0 degrees on tail-plane and approximately
>> >>1/6th
>> >>of a degree positive on the wing. The CG is about right and I don't 
>> >>want
>> >>to
>> >>go any further forward as it creates too much work when rolling in 45
>> >>degree
>> >>up lines.
>> >>
>> >>
>> >>
>> >>I know most of you will say that the model is fairly well trimmed. The
>> >>model
>> >>is pure pleasure to fly in the calm and really locks on well however
>> >>when
>> >>the wind comes up it is a different animal to fly. The model gets
>> >>knocked
>> >>around and I find it very difficult to lock in a line. I am only 
>> >>talking
>> >>about moderate wind here. My other model (Alliance) seems to handle the
>> >>windy conditions better.  I don't want to go any heavier in the nose
>> >>otherwise rolls become too much work. I would actually like to bring my
>> >>CG
>> >>further back but it will make the model even more difficult to fly in
>> >>the
>> >>wind. CG is currently 5 mm behind rear of wing tube. Model weight is
>> >>4.72
>> >>KG
>> >>
>> >>
>> >>
>> >>Question: Will changing wing incidence have any effect on model 
>> >>behavior
>> >>in
>> >>windy weather without affecting the rest of my settings / trimming. I
>> >>only
>> >>have 1/6th of degree positive and I know a lot of people run anywhere
>> >>between 0.25 to 0.5 degree on their models.
>> >>
>> >>
>> >>
>> >>Thanks
>> >>
>> >>
>> >>
>> >>Peter
>> >>
>> >>
>> >>
>> >>
>> >>
>> >
>> >
>> >><< winmail.dat >>
>> >
>> >
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