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Wing incidence on Giant scale ?? - 12/2/2012 9:10 PM   
Flyer88


 

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From: CALGARY, AB, CANADA
Status: offline 		Anyone ever check the incidence on their Pilot Sbach ???

Curious to know if its worth putting some incidence adjusters on my plane ??

Any comments ??

< Message edited by Flyer88 -- 12/3/2012 3:23 PM >

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RE: Wing incidence on Giant scale ?? - 12/2/2012 9:27 PM   
speedracerntrixie


 

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Status: online 		I did a repair job on a 100cc Pilot Sbach for a customer a couple years back. What I found is that this particular one was pretty darned close. My customer had the engine thrust angles all jacked up tying to compensate for an aft CG. I moved the batteries forward and reset the thrust to zero and it flew a ton better. IMO once you get the CG dialed in and make a few adjustments you are good to go without adjusters. You may want to measure the airplane. Usually having the thrust at zero, stab at zero and wing at .5 degrees positive is a good starting point. Always set the CG first before any other trimming as CG influences exerything. If you get halfway through trimming and change the CG, you will have to start all over again.


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RE: Wing incidence on Giant scale ?? - 12/2/2012 11:19 PM   
pe reivers



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Status: online 		If you want a plane to be neutral on all axes, it needs a symmetrical airfoil, stab in line with the wing, zero engine downthrust, zero incidence. Flight is adjusted using the COG and Tx sticks only.


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RE: Wing incidence on Giant scale ?? - 12/2/2012 11:46 PM   
speedracerntrixie


 

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quote:

ORIGINAL: pe reivers

If you want a plane to be neutral on all axes, it needs a symmetrical airfoil, stab in line with the wing, zero engine downthrust, zero incidence. Flight is adjusted using the COG and Tx sticks only.



I disagree. When an airplane is set to 0-0-0 one must carry a tad of up elevator trim to get the wing to fly with a positive AOA. This pos AOA is needed to generate enough lift to carry the wight of the aircraft. The result will be an airplane that pulls to the canopy on up and down lines. Adding a little pos to the wing keeps the thrust line and stab line at zero where they belong.  The only real downside to this is that the airplane will require a toch more forward stick while inverted however the pro's outweigh the con's.



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RE: Wing incidence on Giant scale ?? - 12/3/2012 3:38 AM   
underdw


 

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Status: offline 		I built my Dalton 300MEL with wing incidence adjusters. Initially set the wing at +0.5deg and have never needed to touch it.
(I think the plans called for 0deg on the wing) I also believe the engine and stab are at 0deg.

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RE: Wing incidence on Giant scale ?? - 12/3/2012 11:58 AM   
pe reivers



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quote:

ORIGINAL: speedracerntrixie


quote:

ORIGINAL: pe reivers

If you want a plane to be neutral on all axes, it needs a symmetrical airfoil, stab in line with the wing, zero engine downthrust, zero incidence. Flight is adjusted using the COG and Tx sticks only.



I disagree. When an airplane is set to 0-0-0 one must carry a tad of up elevator trim to get the wing to fly with a positive AOA. This pos AOA is needed to generate enough lift to carry the wight of the aircraft. The result will be an airplane that pulls to the canopy on up and down lines. Adding a little pos to the wing keeps the thrust line and stab line at zero where they belong.  The only real downside to this is that the airplane will require a toch more forward stick while inverted however the pro's outweigh the con's.



With all surfaces zero, you need just as much up elevator as down elevator to obtain flying AoA in upright and inverted flight. A built in incidence will always favor a certain plane attitude at the cost of the other.



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RE: Wing incidence on Giant scale ?? - 12/3/2012 12:10 PM   
john josey


 

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quote:

ORIGINAL: speedracerntrixie

I Always set the CG first before any other trimming as CG influences exerything. If you get halfway through trimming and change the CG, you will have to start all over again.



That is possibly the best single piece of advice you could ever give anyone on set-up......good post !


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RE: Wing incidence on Giant scale ?? - 12/4/2012 1:36 AM   
speedracerntrixie


 

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quote:

ORIGINAL: pe reivers


quote:

ORIGINAL: speedracerntrixie


quote:

ORIGINAL: pe reivers

If you want a plane to be neutral on all axes, it needs a symmetrical airfoil, stab in line with the wing, zero engine downthrust, zero incidence. Flight is adjusted using the COG and Tx sticks only.



I disagree. When an airplane is set to 0-0-0 one must carry a tad of up elevator trim to get the wing to fly with a positive AOA. This pos AOA is needed to generate enough lift to carry the wight of the aircraft. The result will be an airplane that pulls to the canopy on up and down lines. Adding a little pos to the wing keeps the thrust line and stab line at zero where they belong.  The only real downside to this is that the airplane will require a toch more forward stick while inverted however the pro's outweigh the con's.



With all surfaces zero, you need just as much up elevator as down elevator to obtain flying AoA in upright and inverted flight. A built in incidence will always favor a certain plane attitude at the cost of the other.





Partly true. As I did state it will require more forward stick while inverted however it leads to better up and down lines. If the airplane was set up nuetral the way I think you have described here, it will have too aft or a CG for precision IMAC flying.  If you look at the current sequences there are lots of rolling elements while on up and down lines especially when you get past intermidiate. Not so many from inverted so it does lead to a lower pilot workload.



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RE: Wing incidence on Giant scale ?? - 12/4/2012 11:31 AM   
pe reivers



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Status: online 		personal preference.


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RE: Wing incidence on Giant scale ?? - 12/11/2012 3:17 PM   
Magne


 

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Status: offline 		Flyer88,

What is the incidence on your model now, and why do you think you need to change it?

Magne

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RE: Wing incidence on Giant scale ?? - 12/15/2012 3:55 PM   
Flyer88


 

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Status: offline 		My Sbach is in transit from Pilot.

I was curious because I have them on my 2m pattern plane and wondered why I dont see them on giant gasser.

But I am curious and will check during the build.



< Message edited by Flyer88 -- 1/25/2013 1:36 PM >

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RE: Wing incidence on Giant scale ?? - 12/19/2012 5:41 PM   
flyncajun


 

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Status: offline 		I sell a trim guide for these issues called " Triangulation Trimming "
and am the originator of the positive inc setup
I sell an Exhaustive laminated trim guide that covers all issues related with trimming prop planes.
My article explanes why it works ( some have repeated some of it here in this forum thank you!

On my site there is an article I put out a few years ago, that changed perception of my methods.
It is used By Christophe ,Chip, Jason ,Andrew, and Brett ( Multiple time f3A world team Members ),as well as many other World class level Pilots.
I have spent 20 years refining this method to better explain how it works.

Here are some discussions that will go into detail with a few guys that may be helpfull as well.
As Always Eat the fish and throw the bones out
http://www.rcuniverse.com/forum/m_9961187/tm.htm

My Trim Guide is 4 pages with a chart that will address what the airplane is doing and give a fix. From pulling to the belly in a upline to
what to do when a airplane pulls in one direction on one knife edge and to another direction on the reverse side.

The testamonials alone should tell you it works

Bryan Hebert
hebertcompetitiondesigns.com

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RE: Wing incidence on Giant scale ?? - 12/20/2012 6:03 PM   
MTK



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quote:

ORIGINAL: pe reivers

personal preference.


Exactly right!! It is personal preference to either move the sticks all over the transmitter to make the plane fly a certain way....or not!!

Most of us that fly precision aerobatics prefer to trim the model as close to neutral in any attitude as practical. We strive to achieve perfect precision flight (read, perfect response) with the absolute minimum interference from us. The lower the workload, the better. Bryan's "how to" is good place to go to for many answers. Although a bunch of good modelers have written varying information on the subject from time to time, he was the first to actually put in words what the actual process that some of us have learned the hard way, truly is.

BTW- a model set-up at 0-0-0  will require different amount on input in elevator, upright vs inverted. The model will likely also require different left and right aileron amounts for constant roll rate for most typical wing planforms and a single rotating prop up front. So I agree it is personal preference to fly the model with variable amount of input based on the model's needs


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RE: Wing incidence on Giant scale ?? - 12/25/2012 4:18 PM   
husafreak


 

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Status: offline 		I visited your site Bryan and found the trim guide but could not figure out how to actually buy one, like a shopping cart? Thanks.

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RE: Wing incidence on Giant scale ?? - 12/26/2012 8:13 PM   
flyncajun


 

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RE: Wing incidence on Giant scale ?? - 1/9/2013 2:39 AM   
garyr1


 

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Status: offline 		Not that I'm any expert but my first incidence situation happened on a 30cc size Sbach. Pitchy-Twitchy and wouldn't stay in trim as speed varied.
I had to first correct cg...it was tail heavy. Annoyingly the thing still varied trim with airspeed and acted unstable in pitch. Started researching and incidence came up quickly.
Went to the LHS, got the Hangar 9 Incidence meter and the long bar and had a look.
Lo and behold, I had a Zero incidence setup, relative to stab. So I worked in about 0.5 degrees positive on the wing by shimming, etc., and BINGO, it acts like an airplane should now.
Two YEARS later and I'm still enjoying the airplane.
Seriously, Zero-Zero is unstable. At least in my experience.
There are a number of so called experts that seem to agree one needs half to three quarters of a degree of positive incidence.

Good luck guys!

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RE: Wing incidence on Giant scale ?? - 1/23/2013 3:52 AM   
Flyer88


 

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quote:

ORIGINAL: garyr1

Not that I'm any expert but my first incidence situation happened on a 30cc size Sbach. Pitchy-Twitchy and wouldn't stay in trim as speed varied.
I had to first correct cg...it was tail heavy. Annoyingly the thing still varied trim with airspeed and acted unstable in pitch. Started researching and incidence came up quickly.
Went to the LHS, got the Hangar 9 Incidence meter and the long bar and had a look.
Lo and behold, I had a Zero incidence setup, relative to stab. So I worked in about 0.5 degrees positive on the wing by shimming, etc., and BINGO, it acts like an airplane should now.
Two YEARS later and I'm still enjoying the airplane.
Seriously, Zero-Zero is unstable. At least in my experience.
There are a number of so called experts that seem to agree one needs half to three quarters of a degree of positive incidence.

Good luck guys!


What brand is your Sbach ??

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RE: Wing incidence on Giant scale ?? - 1/23/2013 12:19 PM   
sensei



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quote:

ORIGINAL: Flyer88


quote:

ORIGINAL: garyr1

Not that I'm any expert but my first incidence situation happened on a 30cc size Sbach. Pitchy-Twitchy and wouldn't stay in trim as speed varied.
I had to first correct cg...it was tail heavy. Annoyingly the thing still varied trim with airspeed and acted unstable in pitch. Started researching and incidence came up quickly.
Went to the LHS, got the Hangar 9 Incidence meter and the long bar and had a look.
Lo and behold, I had a Zero incidence setup, relative to stab. So I worked in about 0.5 degrees positive on the wing by shimming, etc., and BINGO, it acts like an airplane should now.
Two YEARS later and I'm still enjoying the airplane.
Seriously, Zero-Zero is unstable. At least in my experience.
There are a number of so called experts that seem to agree one needs half to three quarters of a degree of positive incidence.

Good luck guys!


What brand is your Sbach ??

I think the sticker on the tail might be telling you something... Here is a link to them.

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&sqi=2&ved=0CC8QFjAA&url=http%3A%2F%2Fwww.pilot-rc.com%2F&ei=z9X_UKfQHLDo2gWb9IDoDA&usg=AFQjCNETha4z8SZWrhCNx_SQVdm4hs-v1g&bvm=bv.41248874,d.b2I&cad=rja

Bob

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RE: Wing incidence on Giant scale ?? - 1/23/2013 2:33 PM   
Flyer88


 

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Status: offline 		Thats my own Sbach....I want to know what company makes Sbachs with zero incidence. Hope its not Pilot.

Havent got mine to check it yet. They had to alter some of the graphics . Should be here in a week.

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RE: Wing incidence on Giant scale ?? - 1/23/2013 11:56 PM   
garyr1


 

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Status: offline 		OK guys...sorry to keep everyone in such suspense!
My 30cc Sbach is a Slipstream unit.
0 incidence.

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RE: Wing incidence on Giant scale ?? - 1/25/2013 1:28 PM   
Flyer88


 

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Status: offline 		Wow shipping was very fast from Pilot . Only 3 days from China !! Wow.



< Message edited by Flyer88 -- 1/26/2013 2:02 AM >

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