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Old Feb 08, 2009, 11:45 AM
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Ljubljana Brnik, Slovenia
Joined Sep 2004
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O.K.! Lets go busy!

I was thinking to begin with a wing today, but I change my mind and cut some plywood parts for the fuselage on CNC and made one subassembly.

It is the center part of the fuselage. This is an reinforcment that will be later installed between fuselage sides, bellow the wing. Actually it is a wing saddle with front and rear "hardpoints" for the wing attachment.

It consists from front and rear bulkheads, servo tray and side parts.

Bulkheads and servo tray are made from White Poplar 3 mm thick plywood, and sides are made out from a 2 mm thick birch plywood.

I glue this subassembly with white glue (Pattex, WOOD Super 3, water proof)


Assembled. Those lightening holes are optional and not necessarry for the scratchbuilders.



All parts before glueing together. Obviously, parts are designed for the CNC, but scratchbuilders will easily avoid some somplicated joints with "plain ones".
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Old Feb 08, 2009, 12:37 PM
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Ljubljana Brnik, Slovenia
Joined Sep 2004
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The horizontal tail is glued.
Now I must sand round (or better..elliptical) cross section and make elevator conical using plane and sandpaper.



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Old Feb 12, 2009, 08:17 PM
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Iso Octane's Avatar
Toronto, Canada
Joined Jun 2003
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Hi Mijta, what's the advantage of the extra-wingspan version over the short wing? Or rather, what's the advantages of each?
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Old Feb 12, 2009, 08:22 PM
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tmtbiker's Avatar
United States, DC, Washington
Joined May 2008
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Quote:
Originally Posted by Iso Octane
Hi Mijta, what's the advantage of the extra-wingspan version over the short wing? Or rather, what's the advantages of each?
Longer wing = more area = lighter wing loading = better thermalling.

(just a guess )
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Old Feb 13, 2009, 12:34 AM
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ultralajt's Avatar
Ljubljana Brnik, Slovenia
Joined Sep 2004
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Quote:
Originally Posted by tmtbiker
Longer wing = more area = lighter wing loading = better thermalling.
(just a guess )
Yes!

And one more sophisticated :

Larger wing span=larger Aspect Ratio=less Induced Drag=better glide angle=lower sink rate=better thermalling

Off course, larger wing span lowers the rudder authority, so a bit more of aileron differential is welcome.

I will build "normal" wing first.. 1,5m

Mitja
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Old Feb 17, 2009, 04:05 PM
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Ljubljana Brnik, Slovenia
Joined Sep 2004
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Today I start assembly of the wing for the Guppy.

Decided for larger wing with span of 170 cm (67") as want to soar on the thermalls and less on the slope.
I think, for the slope and aerobatics, the 1,5m wingspan would be more suitable.

I prepare a building board using two boards with hinges on the middle, so there is no problem to adjust that dihedral break.


I glue the wing plan on the board and cover it with PVC sheet, so glued parts will not stick to the paper. and removing will be easy.


Ribs for the wing. I use plastic bag to avoid loosing parts.



I draw a lower sheeting on the balsa plate, then use metal ruler and sharp knife to cut it out.



I place lower sheeting on the plans and secure it on proper location using pins and scrap balsa pieces. The rear edge of the sheeting is aligned with line on the plans.



Lower spar cap glued to the lower sheeting, while ribs (not glued yet) and some pins holds all together in place, till glue dry.

It is ocasion to dry test for the ribs and LE strip and to identify each wing rib proper place.


Notches in the bottom contour of the rib serve as a guide for proper location of lower spar cap while gluing it to the bottom sheeting.
Note a gap between rib and lower sheeting from spar cap towards the LE. I will take care of that later, when start gluing ribs to their places. Now, the rib is just pressed down to position the spar.


Wingtip side. Ribs prepared at their places. Note raw wingtip from solid balsa. Need some planing and sanding before gluing to the wing. (later)


Spar cap should be firmly glued to the sheeting and true straight.


At dihedral break, the spar is just bending a bit up. Not need for split joint as angle is very small.


I prepare allso some plywood parts. Here you can see (two parts on the bottom) templates for the root and tip airfoil checking.

In the upper right corner are two reinforcements for the sheeting, where aileron wires will exits on the bottom skin at the root of the wing. Upper left part is a saddle for the horizontal tail.


While spar cap was waiting for glue to dry, I made some shots of some other parts, that are already prepared:



Fuselage parts. Bottom sheeting, motor mount and some minor parts are missing here.



Raw ailerons. Need to be sanded down to proper cross section.



A part on the right is ment for a canopy latch system.


Tomorrow will continue to assemble the wing, but first I must prepare some shear webs.
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Old Feb 18, 2009, 01:12 PM
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sodekirk's Avatar
United States, CO, Parker
Joined Sep 2003
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Is the fuselage for the "standard" GUPPY MK II and the rudder / elevator GUPPY MK II the same? Can you build one fuselage and both wings, or is the fuselage different for each wing?

Thanks,
Shawn
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Old Feb 19, 2009, 10:27 AM
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Ljubljana Brnik, Slovenia
Joined Sep 2004
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Quote:
Originally Posted by sodekirk
Is the fuselage for the "standard" GUPPY MK II and the rudder / elevator GUPPY MK II the same? Can you build one fuselage and both wings, or is the fuselage different for each wing?

Thanks,
Shawn
Shawn, the new Guppy can accept all 3 types of wing without any modification.

Mitja
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Old Feb 19, 2009, 01:50 PM
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Joined Aug 2006
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I'm worming up balsa form my new guppy (xl size).
The normal servo hs55 fit inside the new wings or i too big??
Tanks for your wonderful job.
Paolo

PS
when will be ready the plans? attended it's killing me
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Old Feb 23, 2009, 01:02 AM
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Ljubljana Brnik, Slovenia
Joined Sep 2004
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I was back to building a wing over the weekend.


First I install an aluminum tube at root plywood ribs. This tube will accept steel round joiner. I install a round bamboo stick in front and plywood reinforcment for the servo wire exit. At bamboo stick and aluminum tube, I use large ammount of 5 min epoxy.


At the rear end of the root, I glue a piece of plywood as a "hard point" for the rear wing/fuselage attachment.


Strange funny photo? This photo show how I weighted upper D-box sheeting with old magazines. I try this method for a first time and I am pleased with result. Magazines press don very nisely a balsa sheet along the upper curvature of the ribs.



Upper wing sheeting on place.



Leading edge still open. I sand sheeting flush with front edge of the ribs.


I cut a balsa strip for the leading edge and glue it to the wing. Adhesive tape helps to gold balsa on place, while glue dry.


Aileron servo extension wire installed. Seen from bellow. It should be installed before upper balsa sheeting is glued at the root of the wing.


Leading edge sanded. I help myself with a plywood template to check the curvature of the D-box and LE.


Shear web. Note the vertical grain.

Now I must add top root sheeting, top sheeting at servo bay, sand the balsa tip block to shape and glue it to the wing tip, prepare bottom sheeting of the servo bay and alsso add two "aft" robs at servo bay.

And once again to do all that for the right wing halve.

Mitja
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Old Feb 24, 2009, 09:04 AM
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United States, CO, Parker
Joined Sep 2003
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You do beautiful work.
My birthday is coming up in March. I am going to ask for Guppy plans and a bunch of wood as a gift from my family. I hope the plans are ready soon.

Shawn
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Old Mar 01, 2009, 02:53 PM
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Ljubljana Brnik, Slovenia
Joined Sep 2004
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Thanks Shawn! Yes, march is here.....


I was working again on Guppy assembly over that weekend.

As I am short on free time at the moment, you can see the progress on my Blog at: http://ultralajt.webs.com/apps/blog/...ssembly-report

Tomorrow I will make allso some posts here.
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Old Mar 01, 2009, 05:19 PM
Baboon McGoon
ClipperBill's Avatar
Saint Paul, Minnesota, United States
Joined Jun 2002
681 Posts
I'm still working on my original Guppy (both with original and a hotliner wing from the tiled plans that you posted here), but this one looks even better. I've been building for years, but I'm learning a lot of neat tricks from you. Mitja, you do great work and can certainly be called a "Builder's Builder"!
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Old Mar 02, 2009, 06:20 AM
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Australia, VIC, Delacombe
Joined Nov 2003
276 Posts
Hi ultralajt ,I had a lot of fun with my original Guppy,it was my first electric sailplane,and am now looking forward to mark 2.My problem is that I know very little about motors , battries, speed contolers ect.....I'm going to Hong Kong for a holiday in a few weeks and was hoping to get all of the new bits,could you plaese spare the time to give me a detailed list of what I will need(even the brand names),any info you can give !!!!!!
Thanks,
Paul
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Old Mar 02, 2009, 09:16 AM
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ultralajt's Avatar
Ljubljana Brnik, Slovenia
Joined Sep 2004
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Quote:
Originally Posted by 3810
Hi ultralajt ,I had a lot of fun with my original Guppy,it was my first electric sailplane,and am now looking forward to mark 2.My problem is that I know very little about motors , battries, speed contolers ect.....I'm going to Hong Kong for a holiday in a few weeks and was hoping to get all of the new bits,could you plaese spare the time to give me a detailed list of what I will need(even the brand names),any info you can give !!!!!!
Thanks,
Paul
Hi Paul!

My new Guppy will probably use this equippment:

Brushless motor:
Welgard A22/12/15 (as it waits here in my drawer, othervise I will use a Turnigy of same size and power)

Speed regulator (ESC) with BEC:
TowerPro W30A Brushless Speed Controller
http://www.hobbycity.com/hobbycity/s...?idProduct=658

Battery:
ZIPPY 1500mAh 3S1P 20C
http://www.hobbycity.com/hobbycity/s...idProduct=6307

Elevator and rudder servos:
HXT900 9g / 1.6kg / .12sec Micro Servo
http://www.hobbycity.com/hobbycity/s...?idProduct=662

Ailerons servos (8mm thick):
9103MG Metal Gear Servo 4.4g / 0.8kg / .12sec
http://www.hobbycity.com/hobbycity/s...idProduct=8609

Ailerons servos extensions (40 cm long):
40CM Servo Lead (JR) 32AWG Ultra Light
http://www.hobbycity.com/hobbycity/s...idProduct=5595

Folding prop:
Aero Naut 9x7"

Spinner for folding prop:
Folding Headless Prop Spinner 30mm / 3.0mm shaft
http://www.hobbycity.com/hobbycity/s...idProduct=6358

Reciever (RX):
2,4GHz modul
http://www.hobbycity.com/hobbycity/s...idProduct=8286

Transmitter:
Hitec Optic 6 with 2,4MHz modul
http://www.hobbycity.com/hobbycity/s...idProduct=8286

I am sure, that I did not choose the best component one can buy, but I think they will serve for this Guppy well. My Guppy (1,7m wingspan option) will be flying thermalls and weak slope breeze..and ocasionally some gentle arobatics.
No need for vertical climb out...~45 deg climb angle would be suficient.

I will certainly report how this equippment will work on Guppy after test flights.

Regards!

Mitja
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