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Old Feb 16, 2013, 01:36 AM
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UK, Ballymena, Ballymena
Joined Aug 2008
135 Posts
3m guppy

Bought the plans now i just have to scale them up. A4 to A3 doesn't work but found that i can use the poster setting in the printer. Setting a scale of 200% gives the 200% needed.
Set overlap and cut marks
Will do a jpeg of the screen as open office is invalid file.
This consumes a lot of paper, 8 sheets for each A4.
Not all dimensions will be doubled and i will use carbon tow for strengthening.
Still to print out everything and work out materials needed.

Highly recommended that if you use this method print a test set using Mitja's scale
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Last edited by ourbluehorizon; Feb 16, 2013 at 04:13 AM. Reason: corrections
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Old Feb 20, 2013, 08:07 AM
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Joined Sep 2006
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Regarding the aileron servos, I have never used them. I noticed that there is the need to use a Y-cable to split the signal from one channel to two servos. However, won't the direction of motion be the same, therefore resulting in more of a flap effect rather than aileron.

In my mind, I was thinking that you would need to reverse the signal to one servo so that it operates in the opposite direction of motion to its counterpart.


Could you clarify this please.

Thanks

Tom
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Old Feb 20, 2013, 09:23 AM
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United States, MD
Joined Sep 2011
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corkyo4, Y harnesses do operate both servos in the same rotational direction which is what you want for a 2 servo aileron wing on a single channel.

If you look at the first diagram in the link below and imagine both servos turning their horn the same rotational direction, I think It becomes clear.

http://www.rcgroups.com/forums/showp...59&postcount=5

They do make reversing Y harnesses, but this is not what you would use for a typical aileron setup.
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Old Feb 20, 2013, 10:03 AM
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Ljubljana Brnik, Slovenia
Joined Sep 2004
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Quote:
Originally Posted by corkyo4 View Post
Regarding the aileron servos, I have never used them. I noticed that there is the need to use a Y-cable to split the signal from one channel to two servos. However, won't the direction of motion be the same, therefore resulting in more of a flap effect rather than aileron.

In my mind, I was thinking that you would need to reverse the signal to one servo so that it operates in the opposite direction of motion to its counterpart.


Could you clarify this please.

Thanks

Tom
Just think again!
"Y" harnes works for ailerons "worldwide" for sure.
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Old Mar 03, 2013, 09:07 AM
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Joined Aug 2010
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Very informative posts

Did you ever get the Guppy XL designed?
At any rate will begin MK2 this month wanted to wait to see what motor recommendations came from the group. Also wanted to see what bugs infected the design (evidently there were no bugs). I am retired and don't the cash to experiment much. I can only get 1 new plane every 18 months so I need to have good ones. I think this one will be the best and probably my last sailplane.
Thanks for all you guys efforts "you done good!"
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Old Mar 03, 2013, 09:47 AM
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Ljubljana Brnik, Slovenia
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Quote:
Originally Posted by tlar633 View Post
Did you ever get the Guppy XL designed?
Yes! I named it Guppy GS :




Guppy GS Wing HD camera 1080x720 (3 min 51 sec)



Mitja
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Old Mar 03, 2013, 10:25 AM
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How do you recommend converting metric to US measurement since we cannot get metric sizes here.
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Old Mar 03, 2013, 10:52 AM
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Ljubljana Brnik, Slovenia
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Quote:
Originally Posted by tlar633 View Post
How do you recommend converting metric to US measurement since we cannot get metric sizes here.
This could help:
http://www.embroideryline.net/page/page/5134571.htm
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Old Mar 03, 2013, 12:03 PM
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??

Thanks that helps. I was multiply mm by .039 but chart makes it easier.
Now some cases the measurement you give falls between our standard balsa sizes. Do you suggest the next larger size or fall back to the next smaller or just take the closest I can get.
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Old Mar 04, 2013, 02:28 AM
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Ljubljana Brnik, Slovenia
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Just take the closests. If in doubt, use thicker one, and sand slightly when preparing model for covering.
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Old Mar 07, 2013, 02:16 PM
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Apologies for asking a question that has probably been answered before (I just can't find the answer)

Of the available wing options, which gives the slowest and most stable performance?

Thanks

Tom

P.s. I got my guppy 2 laser cut yesterday, the parts look amazing
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Old Mar 07, 2013, 02:23 PM
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Most stable an slowest would be the largest span and polydihedral combined.
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Old Mar 08, 2013, 02:34 AM
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Joined Sep 2005
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Hi Mitja. Thanks for the tip re: Carbon strips glued to balsa for the spar caps. I finally found some spruce and cut it down as best I could to convert it from imperial to metric.
I still might go with the carbon strips as you suggested because I cannot get my saw to cut the spruce down to 2mm for the bottom spar cap and I don't really want to have to sand the spar slots down any further than they already are. If I did that then I would also have to adjust the height of my laser cut shear web as well and I don't want to have to do that!
cheers.
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Old Mar 09, 2013, 09:21 AM
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Could the steel rod (used to join the wings) be changed for a length of the carbon fibre tube used for the tail boom?

Thanks

Tom
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Old Mar 09, 2013, 09:43 AM
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Ljubljana Brnik, Slovenia
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Quote:
Originally Posted by corkyo4 View Post
Could the steel rod (used to join the wings) be changed for a length of the carbon fibre tube used for the tail boom?

Thanks

Tom
NO! There is no space for 6 mm thick joiner.
Usually steel joiner is better than carbon, as when overloaded, steel just bends, while carbon simply broke instantly. You can land plane with bent steel joiner but not with broken carbon joiner.

Mitja
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