Positive wing incidence
08-09-2007, 01:35 PM
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Positive wing incidence
What are some of the characteristics of two much positive in the wings? I've got about .5 degree and its hard to hold a good line inverted and takes more down stick than I "think" it should. The plane flys inverted like its nose heavy so I tried adding tail weight and that just makes everything go south... 
Thanks,
Todd
Thanks,
Todd
08-09-2007, 02:23 PM
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RE: Positive wing incidence
All things else being equal, positive incidence in the wing will make the plane climb. This means you'll need down elevator trim to make the plane fly level. This will help if you have a pitch to the canopy in down lines or knife edge because the down elevator trim will counter it. That being said, I've never liked more than .25 degree poitive in the wing. My planes have never felt locked on with more than that. However, you mention that you're holding more down elevator than you think you should when inverted. Less positive in the wing equates to more up trim, so reducing the incidence will make that situation worse. My guess is that you're dealing with a CG that is too far forward or possibly a thrust problem. There's a handy chart at www.nsrca.org that can help sort all this out. Just remenber that every change is relative to where the plane currently trims out and that adjusting the CG changes everything. Hope this helps!
Verne
Verne
ORIGINAL: tschmidt
What are some of the characteristics of two much positive in the wings? I've got about .5 degree and its hard to hold a good line inverted and takes more down stick than I "think" it should. The plane flys inverted like its nose heavy so I tried adding tail weight and that just makes everything go south...
Thanks,
Todd
What are some of the characteristics of two much positive in the wings? I've got about .5 degree and its hard to hold a good line inverted and takes more down stick than I "think" it should. The plane flys inverted like its nose heavy so I tried adding tail weight and that just makes everything go south...
Thanks,
Todd
08-10-2007, 12:18 PM
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RE: Positive wing incidence
Here are my observations - First, are you referencing wing incidence to the engine thrust line? Is the thrust line referenced to the 0/0 center of the fuselage? Wing incidence will raise or lower the stab flying position. For a given airspeed the wing angle of attack will be the same - change the incidence and the wing will seek the same angle of attack again for that airspeed. The difference is the stab will be higher or lower (as seen in the air) than before. You will then adjust the stabs to seek a 0/0 with new the elevator position. You can then change the engine thrust a bit to get the plane to fly like you want it. The perception of level flight, upright and inverted, can be changed by wing incidence. If you mix in CG changes, the general theory holds, but less wing incidence may be required to make the plane fly level.
sc
sc
08-10-2007, 12:57 PM
#5
RE: Positive wing incidence
your too tail heavy !!!
if,, you are really .5 pos
you have to remember tail weight will make the airplane sensitive .but not responsive and viseversa
move the nose weight forward untill the feel is right more nose weight better elevator feel as always you can go too far both ways But tail heavy can trick you into thinking your nose heavy.
even with .5 pos in the wings when you roll it inverted you should hardly need any elevator input
in fact my airplane rolled to inverted with rudder has a down elevater application requirment delay time of a second
with the c/g right the elevator takes very little movement to make a changeit is much more responsive
make sure the .5 pos is relative to the design thrust line not the engine thrust
and trust this advise
this comes for years of design and development
Bryan
if,, you are really .5 pos
you have to remember tail weight will make the airplane sensitive .but not responsive and viseversa
move the nose weight forward untill the feel is right more nose weight better elevator feel as always you can go too far both ways But tail heavy can trick you into thinking your nose heavy.
even with .5 pos in the wings when you roll it inverted you should hardly need any elevator input
in fact my airplane rolled to inverted with rudder has a down elevater application requirment delay time of a second
with the c/g right the elevator takes very little movement to make a changeit is much more responsive
make sure the .5 pos is relative to the design thrust line not the engine thrust
and trust this advise
this comes for years of design and development
Bryan
08-10-2007, 02:19 PM
#6
RE: Positive wing incidence
Bryan is a smart guy 
We had a chat at Muncie about some trimming things I wanted to fix on the Twister, and he gave me the above advise. At first it sounds backwards from what you would expect, but I have a lot of respect for Bryan so I gave it a go. Let me tell you he is pretty much spot on Its worth trying, I am still playing with my setup to get it just right, but it was amazing how well his suggestions have worked out.
We had a chat at Muncie about some trimming things I wanted to fix on the Twister, and he gave me the above advise. At first it sounds backwards from what you would expect, but I have a lot of respect for Bryan so I gave it a go. Let me tell you he is pretty much spot on Its worth trying, I am still playing with my setup to get it just right, but it was amazing how well his suggestions have worked out.
08-10-2007, 03:56 PM
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RE: Positive wing incidence
Wow, I knew the answer to this one just because Bryan has hammered it into my brain already... But I didn't respond because I figured it would be better coming from him...
08-13-2007, 10:32 AM
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RE: Positive wing incidence
Thanks everyone!
After posting this, I remembered Bryans response to a similar thread so I moved the CG forward. Everything has smoothed out, I can hold a solid inverted line and the plane is locking on very good now. The plane is my own design (Defiant MKII) so I've been trying different CG locations, moving it forward has made a very positive difference..
Thanks Bryan for your response, it's greatly appreciated!
Todd Schmidt
08-13-2007, 05:10 PM
#9
RE: Positive wing incidence
Hi Bryan
I have a trimming question to ask (sorry for hyjacking the thread)
Please explain design thrust line? Do I have to assume the kit designer got this right in the first place?
What do you suggest as a model setup to make it sit in the wind better. Some model designs I have flown just fly better than others in the wind. Is it something to do with the relationship between engine thrust and wing incidence?
I have a trimming question to ask (sorry for hyjacking the thread)
Please explain design thrust line? Do I have to assume the kit designer got this right in the first place?
What do you suggest as a model setup to make it sit in the wind better. Some model designs I have flown just fly better than others in the wind. Is it something to do with the relationship between engine thrust and wing incidence?
08-14-2007, 07:27 PM
#11
RE: Positive wing incidence
ORIGINAL: PeterP
Hi Bryan
I have a trimming question to ask (sorry for hyjacking the thread)
Please explain design thrust line? Do I have to assume the kit designer got this right in the first place?
What do you suggest as a model setup to make it sit in the wind better. Some model designs I have flown just fly better than others in the wind. Is it something to do with the relationship between engine thrust and wing incidence?
Hi Bryan
I have a trimming question to ask (sorry for hyjacking the thread)
Please explain design thrust line? Do I have to assume the kit designer got this right in the first place?
What do you suggest as a model setup to make it sit in the wind better. Some model designs I have flown just fly better than others in the wind. Is it something to do with the relationship between engine thrust and wing incidence?
It is not obvious to me that Todd is tail heavy from his description unless going south means it took even more down elevator inverted.
Jim O
08-14-2007, 09:23 PM
#12
RE: Positive wing incidence
Scott is correct on a few details
However the designer is responsible for setting the thrustline of the airplane ,, How the fuse presents in the air is also part of the equation and the look the designer is going for.
The designer is also reponsible to give the recomended trim and C/g location assuming he knows<G>
I have found that most of the current designs are designed by one person and another is given credit for the design, for it to have "credibility" in the Market!!
And thats where the confusion comes in ,,,,,, nobody involved with the design really knows what the proper trimming setup should be
and the guys claiming to have designed it could fly the airplane with any setup.
Having an airplane set up with no positive angle attack in the wing {as most current designs are today} causes you to fly tail heavy to get the pos. angle desiredfor the wing to create the required lift
This is where all the airplane trim problems start Snaps Suck !! Spins require low rate rudder and are very difficult to stop consistantly , left rudder Knife edge goes to the belly ,
and if you are really tail heavy right rudder knife edge goes to the Belly also,
up and down lines go the the canopy 45 up and down lines are not easy to duplicate and if you apply rudder any where you need a up elevator mix.
Engine thrust is the last thing you should address, and least effective in the overall trim process
The main wing has to create lift independant of the fuse the stab is only used to steer and stablize like the rudder
here is a quick trim method.
First Find out where to get a zero setting on the fuse My designs use the Canopy base,
zero the fuse ,set the wings at .5 pos, put the c/g at 30% MAC
engine {not very important at this stage} 1/2 to 1 deg down and right
fly the airplane to a perfect horizontal trim, then fly both knife edges if the left knife goes to the belly your still too tail heavy Or your .5 pos is not .5 check it again, the right rudder will always go straight before the left rudder knife.
if it goes to the canopy you are nose heavy Or you overshot the pos inc.
when you get this right check your up and down lines I`ll guarantee that you are 99% there
if it pulls to the canopy in the downlines tweek a little more pos in the wing or you might be able to sneak the c/g back a little
Remember nose weight will improve Snaps, Spins , stalls , inverted flying , and landings ,if any of these things are inconsistant you are tail heavy Or the design needs to be tweeked ,
{THIS SET UP" WILL" FLY IN THE WIND BETTER ] because the c/g is correct and the wing is always lifting pos.
I hope this helps,
please,,,,, don`t aurgue if you have not tried this set up,
However if you try it ,,,, you won`t aurgue
Bryan
However the designer is responsible for setting the thrustline of the airplane ,, How the fuse presents in the air is also part of the equation and the look the designer is going for.
The designer is also reponsible to give the recomended trim and C/g location assuming he knows<G>
I have found that most of the current designs are designed by one person and another is given credit for the design, for it to have "credibility" in the Market!!
And thats where the confusion comes in ,,,,,, nobody involved with the design really knows what the proper trimming setup should be
and the guys claiming to have designed it could fly the airplane with any setup.
Having an airplane set up with no positive angle attack in the wing {as most current designs are today} causes you to fly tail heavy to get the pos. angle desiredfor the wing to create the required lift
This is where all the airplane trim problems start Snaps Suck !! Spins require low rate rudder and are very difficult to stop consistantly , left rudder Knife edge goes to the belly ,
and if you are really tail heavy right rudder knife edge goes to the Belly also,
up and down lines go the the canopy 45 up and down lines are not easy to duplicate and if you apply rudder any where you need a up elevator mix.
Engine thrust is the last thing you should address, and least effective in the overall trim process
The main wing has to create lift independant of the fuse the stab is only used to steer and stablize like the rudder
here is a quick trim method.
First Find out where to get a zero setting on the fuse My designs use the Canopy base,
zero the fuse ,set the wings at .5 pos, put the c/g at 30% MAC
engine {not very important at this stage} 1/2 to 1 deg down and right
fly the airplane to a perfect horizontal trim, then fly both knife edges if the left knife goes to the belly your still too tail heavy Or your .5 pos is not .5 check it again, the right rudder will always go straight before the left rudder knife.
if it goes to the canopy you are nose heavy Or you overshot the pos inc.
when you get this right check your up and down lines I`ll guarantee that you are 99% there
if it pulls to the canopy in the downlines tweek a little more pos in the wing or you might be able to sneak the c/g back a little
Remember nose weight will improve Snaps, Spins , stalls , inverted flying , and landings ,if any of these things are inconsistant you are tail heavy Or the design needs to be tweeked ,
{THIS SET UP" WILL" FLY IN THE WIND BETTER ] because the c/g is correct and the wing is always lifting pos.
I hope this helps,
please,,,,, don`t aurgue if you have not tried this set up,
However if you try it ,,,, you won`t aurgue
Bryan
08-14-2007, 09:50 PM
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RE: Positive wing incidence
Been flying Pattern for a year and still trying to learn how to trim an airplane. I refer the NSRCA trim chart as well as others. Problem is a lack of experence at this level of trimming. My son and I just finished his Venus II . First flight required almost all available up trim (from radio), about 1/8" for level flight. Noticed that tail came up quickly on TO and had to use considerable up elevator to get airborne. CG was at forward limit. Moved CG to center of range w/o much change. If this is a CG problem, it appears it will be well out of the design limit to cause a significant change. Admittedly, I am a little hung up on going outside the recommended limit. The plane does not hold a 45* up line and requires some down stick for inverted flight. How much is too much? Downthrust is 1 degree which is the design spec. Incidence, as well as I can measure it, is zero. Next move is to move CG back in 1/4" increments and see what happens. I welcome your comments.
John
John
08-14-2007, 11:33 PM
#14
RE: Positive wing incidence
ORIGINAL: flyncajun
First Find out where to get a zero setting on the fuse My designs use the Canopy base,
zero the fuse ,set the wings at .5 pos, put the c/g at 30% MAC
engine {not very important at this stage} 1/2 to 1 deg down and right
fly the airplane to a perfect horizontal trim, then fly both knife edges if the left knife goes to the belly your still too tail heavy Or your .5 pos is not .5 check it again, the right rudder will always go straight before the left rudder knife.
if it goes to the canopy you are nose heavy Or you overshot the pos inc.
when you get this right check your up and down lines I`ll guarantee that you are 99% there
if it pulls to the canopy in the downlines tweek a little more pos in the wing or you might be able to sneak the c/g back a little
Remember nose weight will improve Snaps, Spins , stalls , inverted flying , and landings ,if any of these things are inconsistant you are tail heavy Or the design needs to be tweeked ,
Bryan
First Find out where to get a zero setting on the fuse My designs use the Canopy base,
zero the fuse ,set the wings at .5 pos, put the c/g at 30% MAC
engine {not very important at this stage} 1/2 to 1 deg down and right
fly the airplane to a perfect horizontal trim, then fly both knife edges if the left knife goes to the belly your still too tail heavy Or your .5 pos is not .5 check it again, the right rudder will always go straight before the left rudder knife.
if it goes to the canopy you are nose heavy Or you overshot the pos inc.
when you get this right check your up and down lines I`ll guarantee that you are 99% there
if it pulls to the canopy in the downlines tweek a little more pos in the wing or you might be able to sneak the c/g back a little
Remember nose weight will improve Snaps, Spins , stalls , inverted flying , and landings ,if any of these things are inconsistant you are tail heavy Or the design needs to be tweeked ,
Bryan
Jim O
08-15-2007, 09:16 AM
#15
RE: Positive wing incidence
John
do not use the NSRCA trim guide it is wrong ,,, has been wrong for years
use the above method to trim your airplane.
Jim you are on the mark
Bryan
do not use the NSRCA trim guide it is wrong ,,, has been wrong for years
use the above method to trim your airplane.
Jim you are on the mark
Bryan
08-15-2007, 09:53 AM
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RE: Positive wing incidence
Bryan --
Thanks for your well thought out input and experience sharing. Reading your stuff makes me wish I lived next door... I have a couple of questions:
When you say "left knife edge" are you referring to using left rudder or having rolled to the plane's left side (down)?
What tool or method do you recommend/use to determine wing incidence (or stab incidence for that matter) once the fuselage is setting at zero?
Sure do like the looks of that Shinden!
Thanks, Tom
Thanks for your well thought out input and experience sharing. Reading your stuff makes me wish I lived next door... I have a couple of questions:
When you say "left knife edge" are you referring to using left rudder or having rolled to the plane's left side (down)?
What tool or method do you recommend/use to determine wing incidence (or stab incidence for that matter) once the fuselage is setting at zero?
Sure do like the looks of that Shinden!
Thanks, Tom
08-24-2008, 09:17 AM
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RE: Positive wing incidence
well , i have a question for the stab incident ..... i am now almost finished a 2 m pattern plane , it is a one piece wing n the stab
are adjusteble . In the menu it say -0.25 to .5 ........ so what should i start at ?? i have been told to set it 0,0 to fly ....
0 wing and stab -0.25 "when it is negatif " does it mean the leading edge of the stab pointed down ....? am i right ??
i am abit confuse. . . ...... help !!
this is my first 2m pattern plane !!
are adjusteble . In the menu it say -0.25 to .5 ........ so what should i start at ?? i have been told to set it 0,0 to fly ....
0 wing and stab -0.25 "when it is negatif " does it mean the leading edge of the stab pointed down ....? am i right ??
i am abit confuse. . . ...... help !!
this is my first 2m pattern plane !!
08-25-2008, 07:01 PM
#18
RE: Positive wing incidence
imma join in the hyjacking of the thread as well..
CA Models Genesis w/ 170DZ
left rudder KE pulls to the belly just barely
Right rudder KE pulls the canopy alot
Up and Downlines both pull to the canopy enough so much that it will practically do the 2nd corner of a square loop on its own.
Wing Incidence is set at .5 degree positive, stabs at Zero
CG set around 1/2" forward of the wing tube. (CG is called for .63" ahead of the wingtube)
2nd flight i added 2oz of lead to the nose, which helped the Left KE a good bit, so i added another 1oz to the nose which helped as well. I've been debating on if i should add another once of weight to the nose and then more positive incidence to the wings to help out the vertical lines, but kinda stumped.. suggestions?
CA Models Genesis w/ 170DZ
left rudder KE pulls to the belly just barely
Right rudder KE pulls the canopy alot
Up and Downlines both pull to the canopy enough so much that it will practically do the 2nd corner of a square loop on its own.
Wing Incidence is set at .5 degree positive, stabs at Zero
CG set around 1/2" forward of the wing tube. (CG is called for .63" ahead of the wingtube)
2nd flight i added 2oz of lead to the nose, which helped the Left KE a good bit, so i added another 1oz to the nose which helped as well. I've been debating on if i should add another once of weight to the nose and then more positive incidence to the wings to help out the vertical lines, but kinda stumped.. suggestions?
08-25-2008, 08:13 PM
#19
RE: Positive wing incidence
Thomas,
After going thru the 'triangulation trimming' method, I ended up with the settings below. Prior to that, the plane would not lock in, the tail was skidding around, lots of pitch to the belly on left rudder KE, etc. The following setup fixed a lot of those problems.
CG - 3/4" - 7/8" ahead of the front edge of the wing tube (I know, that's quite a bit further forward than recommended but it works)
with motor at 1 degree downthrust (matches nose ring on mine) the stab is at 0 degrees and the wing is at +.6 degrees.
No mix either knife edge, slight pull to canopy on down line after about 200 ft. I choose to fly it thru that rather than mix in slight down elev with low throttle. Mixing that out screws up too many other things during maneuvers.
Woodie
After going thru the 'triangulation trimming' method, I ended up with the settings below. Prior to that, the plane would not lock in, the tail was skidding around, lots of pitch to the belly on left rudder KE, etc. The following setup fixed a lot of those problems.
CG - 3/4" - 7/8" ahead of the front edge of the wing tube (I know, that's quite a bit further forward than recommended but it works)
with motor at 1 degree downthrust (matches nose ring on mine) the stab is at 0 degrees and the wing is at +.6 degrees.
No mix either knife edge, slight pull to canopy on down line after about 200 ft. I choose to fly it thru that rather than mix in slight down elev with low throttle. Mixing that out screws up too many other things during maneuvers.
Woodie
08-25-2008, 08:21 PM
#20
RE: Positive wing incidence
Woodie, thanks for the tip. It sounds as if im going to have to reposition my reciever from the back of the canopy hatch area to the just behind the firewall. Along w/ a heavier battery than the 2s 2170mah lipo i'm running now. I guesstimate that in order for me to get my CG as far forward as you have yours, i'd need another 4 to 6 oz of lead in the nose.
08-25-2008, 11:36 PM
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RE: Positive wing incidence
I flew a Genesis that Bryan Hebert set up, and what woodie listed is about where mine was set up. Also, like he said, the Genesis can't be completely trimmed to fly mix free (design issues). The worst characteristic mine had was dropping the nose on rudder input when upright. It was worse with right rudder than with left. I probably could have stood to have a little more weight in the nose, but the equipment was as far forward as it could be, and the plane was right at 11 pounds and couldn't have anymore weight added to it.
08-26-2008, 01:12 PM
#22
RE: Positive wing incidence
ORIGINAL: mjfrederick
I flew a Genesis that Bryan Hebert set up, and what woodie listed is about where mine was set up. Also, like he said, the Genesis can't be completely trimmed to fly mix free (design issues). The worst characteristic mine had was dropping the nose on rudder input when upright. It was worse with right rudder than with left. I probably could have stood to have a little more weight in the nose, but the equipment was as far forward as it could be, and the plane was right at 11 pounds and couldn't have anymore weight added to it.
I flew a Genesis that Bryan Hebert set up, and what woodie listed is about where mine was set up. Also, like he said, the Genesis can't be completely trimmed to fly mix free (design issues). The worst characteristic mine had was dropping the nose on rudder input when upright. It was worse with right rudder than with left. I probably could have stood to have a little more weight in the nose, but the equipment was as far forward as it could be, and the plane was right at 11 pounds and couldn't have anymore weight added to it.
08-26-2008, 02:45 PM
#23
RE: Positive wing incidence
Original question was about WING INCIDENCE
As the more informed have noted - the wing incidence -for flight -will NOT change beyond what is needed for desired lift. The rest of the model will simply change RELATIVE AOA (that's angle of attack) as the wing is positioned differently
You can't fool mother nature. To restate the obvious
if you raise the wing le position relative to effective trailing edge -position (add Pos incidence
for the same lift , the fuselage MUST assume a relatively higher tail attitude in flight-
correct alignment of wing-stab and engine are important -of course - but the wing does NOT change AOA unles weight of the model changes
Its just Basic Flight 101
depending on the model - you may want it to fly tail high or tail low . We once did a scale Zlin 50 for TOC - it finished flown by Dave Brown- in about 1976(?) second as I recall- pretty good flyer . not like the flying flounder setups but pretty good.
As the more informed have noted - the wing incidence -for flight -will NOT change beyond what is needed for desired lift. The rest of the model will simply change RELATIVE AOA (that's angle of attack) as the wing is positioned differently
You can't fool mother nature. To restate the obvious
if you raise the wing le position relative to effective trailing edge -position (add Pos incidence
for the same lift , the fuselage MUST assume a relatively higher tail attitude in flight-
correct alignment of wing-stab and engine are important -of course - but the wing does NOT change AOA unles weight of the model changes
Its just Basic Flight 101
depending on the model - you may want it to fly tail high or tail low . We once did a scale Zlin 50 for TOC - it finished flown by Dave Brown- in about 1976(?) second as I recall- pretty good flyer . not like the flying flounder setups but pretty good.
08-26-2008, 08:36 PM
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RE: Positive wing incidence
ORIGINAL: flyncajun
Scott is correct on a few details
However the designer is responsible for setting the thrustline of the airplane ,, How the fuse presents in the air is also part of the equation and the look the designer is going for.
The designer is also reponsible to give the recomended trim and C/g location assuming he knows<G>
I have found that most of the current designs are designed by one person and another is given credit for the design, for it to have "credibility" in the Market!!
And thats where the confusion comes in ,,,,,, nobody involved with the design really knows what the proper trimming setup should be
and the guys claiming to have designed it could fly the airplane with any setup.
Having an airplane set up with no positive angle attack in the wing {as most current designs are today} causes you to fly tail heavy to get the pos. angle desiredfor the wing to create the required lift
This is where all the airplane trim problems start Snaps Suck !! Spins require low rate rudder and are very difficult to stop consistantly , left rudder Knife edge goes to the belly ,
and if you are really tail heavy right rudder knife edge goes to the Belly also,
up and down lines go the the canopy 45 up and down lines are not easy to duplicate and if you apply rudder any where you need a up elevator mix.
Engine thrust is the last thing you should address, and least effective in the overall trim process
The main wing has to create lift independant of the fuse the stab is only used to steer and stablize like the rudder
here is a quick trim method.
First Find out where to get a zero setting on the fuse My designs use the Canopy base,
zero the fuse ,set the wings at .5 pos, put the c/g at 30% MAC
engine {not very important at this stage} 1/2 to 1 deg down and right
fly the airplane to a perfect horizontal trim, then fly both knife edges if the left knife goes to the belly your still too tail heavy Or your .5 pos is not .5 check it again, the right rudder will always go straight before the left rudder knife.
if it goes to the canopy you are nose heavy Or you overshot the pos inc.
when you get this right check your up and down lines I`ll guarantee that you are 99% there
if it pulls to the canopy in the downlines tweek a little more pos in the wing or you might be able to sneak the c/g back a little
Remember nose weight will improve Snaps, Spins , stalls , inverted flying , and landings ,if any of these things are inconsistant you are tail heavy Or the design needs to be tweeked ,
{THIS SET UP" WILL" FLY IN THE WIND BETTER ] because the c/g is correct and the wing is always lifting pos.
I hope this helps,
please,,,,, don`t aurgue if you have not tried this set up,
However if you try it ,,,, you won`t aurgue
Bryan
Scott is correct on a few details
However the designer is responsible for setting the thrustline of the airplane ,, How the fuse presents in the air is also part of the equation and the look the designer is going for.
The designer is also reponsible to give the recomended trim and C/g location assuming he knows<G>
I have found that most of the current designs are designed by one person and another is given credit for the design, for it to have "credibility" in the Market!!
And thats where the confusion comes in ,,,,,, nobody involved with the design really knows what the proper trimming setup should be
and the guys claiming to have designed it could fly the airplane with any setup.
Having an airplane set up with no positive angle attack in the wing {as most current designs are today} causes you to fly tail heavy to get the pos. angle desiredfor the wing to create the required lift
This is where all the airplane trim problems start Snaps Suck !! Spins require low rate rudder and are very difficult to stop consistantly , left rudder Knife edge goes to the belly ,
and if you are really tail heavy right rudder knife edge goes to the Belly also,
up and down lines go the the canopy 45 up and down lines are not easy to duplicate and if you apply rudder any where you need a up elevator mix.
Engine thrust is the last thing you should address, and least effective in the overall trim process
The main wing has to create lift independant of the fuse the stab is only used to steer and stablize like the rudder
here is a quick trim method.
First Find out where to get a zero setting on the fuse My designs use the Canopy base,
zero the fuse ,set the wings at .5 pos, put the c/g at 30% MAC
engine {not very important at this stage} 1/2 to 1 deg down and right
fly the airplane to a perfect horizontal trim, then fly both knife edges if the left knife goes to the belly your still too tail heavy Or your .5 pos is not .5 check it again, the right rudder will always go straight before the left rudder knife.
if it goes to the canopy you are nose heavy Or you overshot the pos inc.
when you get this right check your up and down lines I`ll guarantee that you are 99% there
if it pulls to the canopy in the downlines tweek a little more pos in the wing or you might be able to sneak the c/g back a little
Remember nose weight will improve Snaps, Spins , stalls , inverted flying , and landings ,if any of these things are inconsistant you are tail heavy Or the design needs to be tweeked ,
{THIS SET UP" WILL" FLY IN THE WIND BETTER ] because the c/g is correct and the wing is always lifting pos.
I hope this helps,
please,,,,, don`t aurgue if you have not tried this set up,
However if you try it ,,,, you won`t aurgue
Bryan
Brandon L..... a wanna be designer/builder
p.s.- matt, you got that quest lined out yet?
08-26-2008, 09:28 PM
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RE: Positive wing incidence
I finished what I could short of glass and paint. Bryan has it now, he's working on the rest. Shouldn't be too much longer (I hope). Can't wait to get in the air again.