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Old Dec 27, 2012, 12:37 PM
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United States, CA, Midway City
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Quote:
Originally Posted by IHAVAWDY View Post
question

fnnwizard; With a unpublished airfoil and the fact that it (airfoil) changes from root to tip, how do you run such polar graphs? I'm trying to do the same thing with a changing airfoil, but having difficulties...
Getting an accurate tracing from the tip's root give's a decent foil to work with. From there, one can do some inverse airfoil modeling. The other thing is to find a dbr (damaged beyond repair) wing and cut it up to get some airfoils.

Quote:
Originally Posted by Rich Burnoski View Post
Hi Tuan,,,

while your away from the christmas tree now,,,,, Id like to get the theoretical data for the "max" camber reflex position at a zooming speed.
Is that possible mr wizard ? Richard
Merry Christmas Rich! The zooming speed for the X2 reflex is right around 2-2.5mm.
For the 3.8, I think the best thing to do to gain zoom height is to run the 3.5 stabs. I wouldn't have believed it myself if I had not tried it back and forth for so long. Small stabs cg'd at 120 for the 3.8 is definitely better.
For a decambered wing of the X2, the requirements (downward force) of the stabs are less than for the X1 sections. Ele authority should not be a problem especially with the lighter fuse with the lighter extremities. Yaw stability should be slightly better due to the xtra distance from cg to vstab and the smaller stab not blanketing the rudder as much.
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Last edited by fnnwizard; Dec 27, 2012 at 02:09 PM.
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Old Dec 27, 2012, 11:00 PM
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agreed on the reflex setting, & ----

Yes mr wizard, Tuan, I like where your going with your data.

Surprising to me I actually followed and understand all your info on the last post of yours. Some thing must be wrong with me or maybe I just got the Christmas spirit or drank enough christmas spirits! aaaahhhhhh gulp

The stab sizing thing makes sense for the Xplorer2 3.8. I know the 3.5 Xplorer 1 launches and pulls the line harder than the 3.5 Xplorer 2.

Beginning of the year, 2012,,I was way maximized with the tow hook and ran a some what conservative CG.

I have had some trials and tribulations with stability with the Xplorer2 3.5 on launch using an aggresive launch camber and had to finally result to backing off to a optimized not maximized tow hook position. Ive chased the elevator preset all year and have been snake bit when launching on braided line, and combination of braided and mono. I'm having no problem with launch set up on mono because its a consistant launch power. Braided sucks for every thing about a launch and then the wind comes up..... What a crap shoot launching off braided line. The plane set up has to be so conservative we might as well be flying planes from the 1970's. R
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Old Dec 28, 2012, 01:23 PM
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United States, CA, Midway City
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Quote:
Originally Posted by Rich Burnoski View Post
Yes mr wizard, Tuan, I like where your going with your data.

Surprising to me I actually followed and understand all your info on the last post of yours. Some thing must be wrong with me or maybe I just got the Christmas spirit or drank enough christmas spirits! aaaahhhhhh gulp

The stab sizing thing makes sense for the Xplorer2 3.8. I know the 3.5 Xplorer 1 launches and pulls the line harder than the 3.5 Xplorer 2.

Beginning of the year, 2012,,I was way maximized with the tow hook and ran a some what conservative CG.

I have had some trials and tribulations with stability with the Xplorer2 3.5 on launch using an aggresive launch camber and had to finally result to backing off to a optimized not maximized tow hook position. Ive chased the elevator preset all year and have been snake bit when launching on braided line, and combination of braided and mono. I'm having no problem with launch set up on mono because its a consistant launch power. Braided sucks for every thing about a launch and then the wind comes up..... What a crap shoot launching off braided line. The plane set up has to be so conservative we might as well be flying planes from the 1970's. R
Thank's for the feedback Rich. haha on the wizard remarks, I should change my sn.
Anyhow, the fuse I have for the X2 3.5/8 has the hook slot aft about 8mm compared to my X1 3.5/8 fuses. On the X1s, I was running hook a full 10mm aft of the original slot, which means I had to slot it back that extra 10mm.
That means on current x2 fuses we could run the hook all the way back in the slot and still be conservative. Are you ( or anyone else) back that far?

With regards to launch flap and mono vs braided, I too had a heck of a time keeping same settings for the different winch power setups.
It basically came down to:
If launching from F3B with mono, and flaps and ele were optimized, launching on braided would be same flaps or slightly less with more down ele. Hook was always in same place.

The more pretension that can be held the more flaps one can have initially.
The root airfoil for the X2 is the same as the X1. I am not sure where the transition to the X2 foil starts, but its probably safe to say that the launch flaps for the X2 could use an extra 1- 2 degrees compared to X1.

I'll post my findings ( XFLR and real life) once I have gathered the data for the launches but I am having a hard time finding time to build the darn planes.
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Old Dec 28, 2012, 02:36 PM
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I don't think there is any transition in the foil. I think the area between the little ledges on center panel bottom where the fuse mates is the only section of the wing that shares the same foil as the X.
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Old Dec 28, 2012, 03:08 PM
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Originally Posted by ak79 View Post
I don't think there is any transition in the foil. I think the area between the little ledges on center panel bottom where the fuse mates is the only section of the wing that shares the same foil as the X.
Yeah, I would tend to agree with you AK. I'll have to find my X1 center panel templates to compare to know for sure.

On another note, for the X2, 3 camber settings should be sufficient for the 3 normal flight modes ( cruise, thermal, speed). Whereas, for the X1, I really needed 4 (cruise, thermal, speed 1, speed 2) ; with the speed 2 being the zoom speed reflex settings.
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Old Dec 28, 2012, 06:14 PM
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Finally made more of my MPX plug adaptor plates if anyone needs any.
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Old Dec 28, 2012, 06:31 PM
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Originally Posted by fnnwizard View Post
Yeah, I would tend to agree with you AK. I'll have to find my X1 center panel templates to compare to know for sure.

On another note, for the X2, 3 camber settings should be sufficient for the 3 normal flight modes ( cruise, thermal, speed). Whereas, for the X1, I really needed 4 (cruise, thermal, speed 1, speed 2) ; with the speed 2 being the zoom speed reflex settings.
Tuan, I'm no engineer or anything but I've been fooling around with a 5-6mm camber setting for no air, calm min sink. Seems to work very well, Larry told me to try it out. Your thoughts?
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Old Dec 28, 2012, 07:34 PM
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Originally Posted by ak79 View Post
Finally made more of my MPX plug adaptor plates if anyone needs any.
I was just about to pull the trigger on some of these, PM will be sent shortly Do you make the other side as well?Female side not left /right LOL
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Old Dec 28, 2012, 07:41 PM
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Originally Posted by IHAVAWDY View Post
I was just about to pull the trigger on some of these, PM will be sent shortly Do you make the other side as well?Female side not left /right LOL
There are 3 plates, two are for the fuse side. The other thicker plate is for the wing. So ya, you get parts for both sides.
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Old Dec 28, 2012, 08:09 PM
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Originally Posted by ak79 View Post
Tuan, I'm no engineer or anything but I've been fooling around with a 5-6mm camber setting for no air, calm min sink. Seems to work very well, Larry told me to try it out. Your thoughts?
+1 on 5-6 mm that plane will just hang in the sky with that setting.
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Old Dec 28, 2012, 09:43 PM
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Originally Posted by ak79 View Post
Tuan, I'm no engineer or anything but I've been fooling around with a 5-6mm camber setting for no air, calm min sink. Seems to work very well, Larry told me to try it out. Your thoughts?
That would seem about right just basing on X1's best float at 4mm camber.
I'll have some time later this evening to run the airfoils with the various cambers to see theoreticals.

With 5-6mm of camber the speed envelope to fly efficiently is very narrow (probably within 1-2 mph) so it should only be used if you can fly at that exact speed. Usually this means hands off and no banking and it would only be in very calm air.

based on the weights I'm reading, and XFLR predictions the min sink airspeed would be close to 15-16mph. This is actually pretty easy to confirm if we can find very dead air to fly in.
I was able to figure accurately flying speed by using a video camera set back far enough to capture 50+yds of field of vision.
The camera was set right at ground level square to a lightpole. 25 yards (75ft) to the side of the light pole I put up a tripod as a sighting device.

Fly the plane at about 50ft high from end of lightpole to other side and when it crosses the sighting device, I would raise the tx so the camera can catch that to mark the crossing.
Analysing the video, you would get ground speed and when it is dead calm that is your airspeed.
This was much more accurate than any onborad flight recorder!
Of course, you want to start the crossing way beofre the lightpole so the plane has time to settle into it's constant speed for the mode. Should be able to do at least 2 passes at 50 ft. This is also a good way to set ele for other flight modes as well.
In one outing I was able to learn speed to fly and ele compensation for each flight modes compared to a few seasons of flying and guessing.
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Old Dec 28, 2012, 11:43 PM
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Can someone weigh their standard SUSA fuse side harness?
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Old Dec 29, 2012, 07:36 PM
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This XFLR takes up much more time to do with al the various configs.
Ok so the numbers suggests the min sink camber for the various X2's to be:

3.5 X2 = 3 degrees ~3.7mm
3.8 X2 = 4 degrees ~ 5 mm
4.0 X2 = 4-5 degrees ~ 5-6.2mm

These are what would be considered flyable settings. For instance on the 3.5X the data says min sink could be achieved with 4 degrees of camber, but the speed to fly needs to be exact and not deviate by more than .5 mph. It would be impossible for me to fly at that exact speed so the 3 degrees of camber would be much easier.
With regards to dialing in min sink speed once you have cambered in, just add up ele til the ship stalls. 2-3mph faster than this is where the min sink speed is or pretty darn close enough. Depending on the your radio, it could be 2 clicks or 20 clicks of down ele trim
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Old Dec 29, 2012, 08:19 PM
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Strong work Tuan
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Old Dec 31, 2012, 06:08 PM
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I felt as if my x2 3.8 flew better than my 3.5, almost identical settings. So I checked CG's again and the 3.8 is at 123, where the 3.5 was at 118. So I think Web is right on the CG thing, for my tastes anyway.

I was able to shift my 3.5 CG back to 121 with a lighter fuse harness, but I will have to add tail weight or ditch my switch to do it without adding weight. Looking forward to flying them back to back soon.
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