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Q2 and Q-200 Airfoils
14 years 11 months ago #815
by NateD2
Replied by NateD2 on topic Re:Q2 and Q-200 Airfoils
Dan,
My plan was to use the airfoils in the database as the templates and then add the trailing edge modifications from the plans for the elevators and ailerons etc...
I feel it is much better to start with the 'official' airfoil profile and then fit that to what is on the plans. The end result will have less errors then me trying to trace the airfoils on the plans. Additionally I hope to have a better accuracy then other wise would be available.
I fully intend to reproduce the Q2/Q200 from plans as best as possible. At this point there are some small changes that were needed to the fuselage to maintain the cross section curvature... but we're talking very small such as increasing the size of the firewall bulkhead by 1/2".
Unfortunately on the computer side tracing produces some undesirable errors in surface smoothness due to the effects of resolution variation in images and assigning 4 decimal data points to them.
What I have done is started with pure tracings and then cleaned up the data to make them look right.
In 3D computers are very picky about how close together data points are. in some cases the tracings produced errors of 1/8" when scaled to full size. I fixed these problems by tweaking data points and mirroring parts to make sure the aircraft is fully symmetrical.
At any rate the good news is that I figured out how to directly import that .dat files into my CAD program. So I get a perfect shape of the airfoil. All that has to be done is fit the elevator/flap/rudder shapes to the airfoil.
My plan was to use the airfoils in the database as the templates and then add the trailing edge modifications from the plans for the elevators and ailerons etc...
I feel it is much better to start with the 'official' airfoil profile and then fit that to what is on the plans. The end result will have less errors then me trying to trace the airfoils on the plans. Additionally I hope to have a better accuracy then other wise would be available.
I fully intend to reproduce the Q2/Q200 from plans as best as possible. At this point there are some small changes that were needed to the fuselage to maintain the cross section curvature... but we're talking very small such as increasing the size of the firewall bulkhead by 1/2".
Unfortunately on the computer side tracing produces some undesirable errors in surface smoothness due to the effects of resolution variation in images and assigning 4 decimal data points to them.
What I have done is started with pure tracings and then cleaned up the data to make them look right.
In 3D computers are very picky about how close together data points are. in some cases the tracings produced errors of 1/8" when scaled to full size. I fixed these problems by tweaking data points and mirroring parts to make sure the aircraft is fully symmetrical.
At any rate the good news is that I figured out how to directly import that .dat files into my CAD program. So I get a perfect shape of the airfoil. All that has to be done is fit the elevator/flap/rudder shapes to the airfoil.
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14 years 11 months ago #820
by admin
Flying an aeroplane with only a single propeller to keep you in the air. Can you imagine that?
— Captain Picard, from 'Star Trek: The Next Generation' episode 'Booby Trap.'
Replied by admin on topic Re:Q2 and Q-200 Airfoils
Nate,
Again you're scaring me here. You are obviously re-inventing the wheel, but don't even realize that you're doing it!
First off the airfoil you're showing in this thread is not even the correct LS1 Mod airfoil. The one you've chosen is MUCH fatter than the one actually used on the Quickies.
The wrong airfoil will result in unknown flying qualities. Deviating from the templates will result in unknown flying qualities. Therefore, I don't recommend you make your work available to others until you've had a chance to put your own butt on the line in your design.
Secondly, I tried going down this path not too long ago. Please see the following post:
www.quickheads.com/is-there-any-comparison.html
There were several posts after this about the same subject, but I ended up abandoning the idea of creating "new" templates because I didn't have the spar in the right location to absorb landing loads. I didn't have the template level lines set correctly to account for twist in the wing in flight. . . etc. . . etc. . . etc.
I'm just telling you that this project of yours should not be taken lightly, and I cannot endorse your work. (On my website.) Until I see you flying!
I would much rather you read through everything on this site, read all of the plans, see all of the templates, and then try to incorporate the 30+ years of experience from the Quickie Builders Association by reading all back issues of their newsletter.
Again, others have tried and failed to accomplish what you're attempting. By fail. . . I mean died! Please DO NOT take these decisions lightly.
We all want a better plane. Personally I would prefer to have a safer plane first.
Again I am not trying to squash your enthusiasm, I just want it to be tempered a bit. Speaking as a guy with over 10 years of 3D modeling and animation experience, I know that there is a huge difference between a 3D computer model and a real airplane.
Thanks,
Dan Yager
www.quickheads.com
Again you're scaring me here. You are obviously re-inventing the wheel, but don't even realize that you're doing it!
First off the airfoil you're showing in this thread is not even the correct LS1 Mod airfoil. The one you've chosen is MUCH fatter than the one actually used on the Quickies.
The wrong airfoil will result in unknown flying qualities. Deviating from the templates will result in unknown flying qualities. Therefore, I don't recommend you make your work available to others until you've had a chance to put your own butt on the line in your design.
Secondly, I tried going down this path not too long ago. Please see the following post:
www.quickheads.com/is-there-any-comparison.html
There were several posts after this about the same subject, but I ended up abandoning the idea of creating "new" templates because I didn't have the spar in the right location to absorb landing loads. I didn't have the template level lines set correctly to account for twist in the wing in flight. . . etc. . . etc. . . etc.
I'm just telling you that this project of yours should not be taken lightly, and I cannot endorse your work. (On my website.) Until I see you flying!
I would much rather you read through everything on this site, read all of the plans, see all of the templates, and then try to incorporate the 30+ years of experience from the Quickie Builders Association by reading all back issues of their newsletter.
Again, others have tried and failed to accomplish what you're attempting. By fail. . . I mean died! Please DO NOT take these decisions lightly.
We all want a better plane. Personally I would prefer to have a safer plane first.
Again I am not trying to squash your enthusiasm, I just want it to be tempered a bit. Speaking as a guy with over 10 years of 3D modeling and animation experience, I know that there is a huge difference between a 3D computer model and a real airplane.
Thanks,
Dan Yager
www.quickheads.com
Flying an aeroplane with only a single propeller to keep you in the air. Can you imagine that?
— Captain Picard, from 'Star Trek: The Next Generation' episode 'Booby Trap.'
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14 years 11 months ago #821
by NateD2
Replied by NateD2 on topic Re:Q2 and Q-200 Airfoils
Dan,
You are right. I originally asked someone to verify the airfoils for me. It appears the LS(1)-0421 mod as listed for the Q1 at the airfoil database isn't the same as the actual LS(1)-0417 airfoil you mentioned.
It appears the Eppler 1212 mod is the correct one (as I listed below). The only question I have is whether it is the Mod or the regular 1212.
Here is a comparison of the LS(1)-0421 Mod and LS(1)- 0417 mod airfoils:
www.worldofkrauss.com/foils/show_compare...%5D=445&id%5B%5D=803
www.worldofkrauss.com/foils/show_compare...B%5D=63&id%5B%5D=796
As you can see from the data the main problem with the 0421 is a 5 degree difference in the stall angle. Additionally the 0421 has a higher peak lift coefficient and more drag.
Compare the 0421 to the 1212 and you see that they have the same basic stall angle. In a canard that isn't what is desirable, which is why the 0417 is a slightly better choice. As the 0421 will reach stall at 10.5 degrees and the main wing will still be producing lift (assuming the angle of incidence to the fuselage is the same).
Here is the LS(1)-0417.dat airfoil plotted in my CAD program.
You are right. I originally asked someone to verify the airfoils for me. It appears the LS(1)-0421 mod as listed for the Q1 at the airfoil database isn't the same as the actual LS(1)-0417 airfoil you mentioned.
It appears the Eppler 1212 mod is the correct one (as I listed below). The only question I have is whether it is the Mod or the regular 1212.
Here is a comparison of the LS(1)-0421 Mod and LS(1)- 0417 mod airfoils:
www.worldofkrauss.com/foils/show_compare...%5D=445&id%5B%5D=803
www.worldofkrauss.com/foils/show_compare...B%5D=63&id%5B%5D=796
As you can see from the data the main problem with the 0421 is a 5 degree difference in the stall angle. Additionally the 0421 has a higher peak lift coefficient and more drag.
Compare the 0421 to the 1212 and you see that they have the same basic stall angle. In a canard that isn't what is desirable, which is why the 0417 is a slightly better choice. As the 0421 will reach stall at 10.5 degrees and the main wing will still be producing lift (assuming the angle of incidence to the fuselage is the same).
Here is the LS(1)-0417.dat airfoil plotted in my CAD program.
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