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Old Sep 28, 2010, 08:40 AM
Circa:1946
Riverratss's Avatar
Joined Jun 2008
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[QUOTE=Rapi;16080756]Hi!

Sorry for not saying a word for so long. Things went almost as I expected ...
The main thing is, that I received a bad illness, and this completely stopped me doing anything. Nothing serious, in a few days I will be okay.


Rapi!

Well?
Did you get to feeling better?

Regards
Jimmy
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Old Oct 03, 2010, 07:35 AM
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Hi Jimmy!

Thank you for the question! I've finally managed to recover, at the moment I'm really fine.

Here are my new pictures, about how my plane looks right now.:

Now the wing is 98% completed except covering. ( Very little finishing works to do )
I really hope that on this week, I can bring the fuselage to the composite workshop, to make the glass fibre finish.

I have the two tail components covered, I prepared the vertical stabilizer with putty, now it's beautiful shiny and smooth ( except for the ugly colour ... ). At first I will paint the whole thing white, and then figure out some markings.... : )

Regards,
Rapi
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Old Oct 03, 2010, 08:34 AM
Circa:1946
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Good Job!!

Rapi!

Looks nice!

Jimmy
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Old Oct 05, 2010, 07:27 AM
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Herefordshire
Joined May 2009
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Looks nice Rapi, I've just finished building Mitja's Guppy Micro Sloper (thread here...http://www.rcgroups.com/forums/showthread.php?t=1205354) so now looking to start my Guppy or I might make the Guppy 2 yet, still undecided
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Old Oct 06, 2010, 03:50 PM
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Thank you for you both !

I've already read the Microsloper thread, I love that plane too. Sad to say I don't know any good slopes here to fly.

Now I feel really close to the finish line, with my Guppy Mk I. I attach a last photo now to show the fresh glass fibre + balsa surface, I think it is really nice looking. Next time I gonna show the finished or almost finished model.

Now the remaining work to do: polish and paint the fuselage, cover the wing, install servos and equipment... and the hard time: canopy. May take a couple of days but I will do my best.
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Old Oct 07, 2010, 05:30 AM
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Ljubljana Brnik, Slovenia
Joined Sep 2004
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Nice Rapi!
Just a hint about canopy!

Make a wooden plug of the canopy...some inches longer than needed, insert izt in a pet plastic bottle and use some scrap wod wedges to press plug really tight inside the bottle.
Now you can go 3 ways...
- you immerse plug&bottle in a pot of boiling water
- you can rotate and move plug&bottle over a gas stowe burner..not close to the flame, but only in the hot air
- you can heat botle using one of these industial hot air blower

Each way, you can easily make a cute canopy.
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Old Oct 08, 2010, 11:40 AM
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Sir!

I appreciate your help very very much. It actually made me believe that making the plug for the canopy is easy enough for me to do. This way, I finished it in about 2 hrs, and even made a #001 canopy, and it proved that my plug is fine.

However, I have to make some adjustments next time to make it perfect, but it is really promising. ( the hot plastic melted on a little spot when I heated it for the forst time, and it took off some of the putty from the plug. )
Otherwise its okay! Thank you again!
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Old Nov 02, 2010, 04:01 AM
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Joined Sep 2009
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hello..my guppy video
Blu-Guppy Bergama'nın İlk Planörü PART-1 (9 min 0 sec)

very nice fly.
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Old Nov 25, 2010, 10:30 AM
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Northern California
Joined Jan 2009
1,846 Posts
I am really interested in building one of these, but how do I print out the plans?

Is there a tiled version somewhere or do I need to take them to print shop to be printed?

:EDIT:

I found them, can't wait to start my Guppy!

HT
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Old Jan 07, 2011, 09:06 PM
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Warner Robins, GA
Joined Apr 2006
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Started on my Guppy today. I'm going with the hotliner version. Do I need to reinforce the wings with a joiner or anything? Or is it good with just the butt joint and the glass cloth?


Oh, I got my plans printed at Office Depot. They charged $6 for a full-sized printout. I also printed out the "guppy templates" and the "guppy hotliner wing-tiled plans" PDFs.
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Old Jan 09, 2011, 09:36 AM
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Quote:
Originally Posted by Xptical View Post
Started on my Guppy today. I'm going with the hotliner version. Do I need to reinforce the wings with a joiner or anything? Or is it good with just the butt joint and the glass cloth?


Oh, I got my plans printed at Office Depot. They charged $6 for a full-sized printout. I also printed out the "guppy templates" and the "guppy hotliner wing-tiled plans" PDFs.
If you like to fly hard, then use spruce spar caps instead of hard balsa, and make firm epoxy joint in the middle of the wing and use at least 2 layers of glass cloth epoxied over the joint..top&bottom.

In some cases very fast flight causes flutter of the vertical tail, bending torsionally the tail bomm, wkat resulted in delamination of outer balsa from carbon tail boom.

So, use proper ammount of glue on the sanded surface of the carbon tube, to get firm "grip" of the glue, and dont push the limits of the flight envelope to far while flying.

Mitja
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Old Jan 09, 2011, 11:59 AM
Your user title is suggestive,
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The fuse is coming along nicely. I laid up the stab and rudder last night. Did the elevator today.


I need to finish up on the fuse and get the tailboom on it tonight. I'll roughen up the boom and the inside of the boom covers and then use Gorilla Glue to bond everything together.

I'll use spruce for the wings as suggested. Maybe I can get some carbon tow for the spars as well.
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Old Jan 14, 2011, 05:56 PM
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. . .
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Old Jan 16, 2011, 04:58 PM
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Hi Mitja,
i'm complete beginner to RC flying, however I want to learn it hard way - doing guppy from plans. I've already started, having 80% fuselage done. I have an access to LPKF milling machine (to make PCBs), which can cut balsa up to 3mm, so I just milled the wing ribs with quite nice success.

I have few rather 'theoretical' questions:

1) I assume you made guppy from scratch. How did you design it? What software? It looks like it was originally designed in 3D and acad 2D made from cuts. Was it a google sketchup or similar?

2) for your CNC designs: how did you generate 'unfolded' drawings of the fuselage carved bottom? (the one made of 4 balsa strips)

3) when you designed guppy, how did you estimate where the CG should be? i guess there must be some theory behind, but i do not have clue what to put to google to find that.

I'm asking because I'd like to 'understand' the technology of the design, so next time be able to do my airplane from scratch....

thanks a lot
david
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Old Jan 17, 2011, 02:05 AM
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Ljubljana Brnik, Slovenia
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Quote:
Originally Posted by dejfson View Post
Hi Mitja,
i'm complete beginner to RC flying, however I want to learn it hard way - doing guppy from plans. I've already started, having 80% fuselage done. I have an access to LPKF milling machine (to make PCBs), which can cut balsa up to 3mm, so I just milled the wing ribs with quite nice success.

I have few rather 'theoretical' questions:

1) I assume you made guppy from scratch. How did you design it? What software? It looks like it was originally designed in 3D and acad 2D made from cuts. Was it a google sketchup or similar?

2) for your CNC designs: how did you generate 'unfolded' drawings of the fuselage carved bottom? (the one made of 4 balsa strips)

3) when you designed guppy, how did you estimate where the CG should be? i guess there must be some theory behind, but i do not have clue what to put to google to find that.

I'm asking because I'd like to 'understand' the technology of the design, so next time be able to do my airplane from scratch....

thanks a lot
david
A story about Guppy is rather long, but I will try to explain it shortly...

I was already RC modeler for about 30 years when I made first Guppy sailplane, so you can imagine, that I already build many models to that day, trim and fly them. Of course with such long period playing with models, there also some knowledge came. Some knowledge came form wrong and some from proper decisions, when attempting to make some own designs. Also I studied many books about aerodynamic in that period, and beside that I fly Hang glider, Paraglider, Ultralight aeroplane, and also Sailplanes in the local aeroclub.

Once, I assume in the year 2004, I came up with idea to build a nice cute RC sailplane for my son. In search for the way to build rigid, sturdy yet simple fuselage, I decided to build so called Pod&boom type fuselage.
As I did not want to bother with plywood for the pod (front part of the fuselage) because I intend it to shape oval, I use 8 mm thick balsa planks to assemble a "box" and then carved out the sharp corners. I even glue some truangular balsa pieces inside the corners, so I can carved out really nice elliptical shape of the fuselage cross sections. I install a carbon tube as an tail boom, but learn, that is somehow too flexible. It looks also rather "ugly", so I use some balsa and hid that carbon tube with balsa, nicely shaped, to achieve smooth transition from the nose, up to the tail of the fuselage.
Tail feathers were balsa latice frame with thin balsa sheeting, both side.
Wing was balsa syrofoam sandwich. In order to spare time carving foam, I choose Aquila airfoil, making templates only for upper airfoil contour.
There was only rough hand drawn contours for this glider made by myself. No real workshop drawings were made.


This was the fery first (Grandfather of all Guppies..)

After first test flights, I named this model Guppy as its belly shape remembering me of the Guppy fish. It was also obvious, that fuselage shape was slightly inspired also with ASW series of sailplanes, (ASW 24, 27, 28..)

Unfortunately, my soon quickly loose his interes in flying RC modells, so Guppy ended on top of an cabinet in my workshop, just collecting the dust.

Couple years ago, a friend, also RC modeller came to me, and see that Guppy in the workshop. He said, it is the most cute RC sailplane he seen up to date! He wanted to build one for himself, but with classic (balsa ribs..) wing. He ask me for the plans, but all I have was a simple layout of the sailplane and 3 view drawing. he wanted to build this sailplane so badly that he ask me to make a plans for it.

I draw a plans and slightly modify the awerall apearance of the Guppy, making some details better, and of course build up wings, that are lighter and better for such small glider.

And a first Guppy plan was born.

My friend very quickly build that Guppy and even install a Permax 280 electric motor and scratch build gears to propell a folding prop.

Everywhere my friend show up with that Guppy, it became obvious, that many modellers was atraccted with that nice shaped sailplane. The most interesting thing was a fact, that allmost anyone believe it is a molded composite fuselage, but it was only a wooden box nicely carved out of balsa wood!


My friend with his Guppy.

And flight of that Guppy:
Guppy sailplane (2 min 15 sec)


As this Guppy atracted many modellers, my friend suggest me, that I should publish plans in our local RC magazine. So, I made apropriate plans (refine plans and squeze it on available format) and publish it. Plans were made in Cad program I use it at my job and I am familiar with.
My Guppy build by this plans, was scratch build using hand tools. no CNC machines were used:


CNC machine is not a "must".


Published plans and assembly article in the Magazine.
(later, plans in very minimized form, were published also in Czech RC modeller magazine)

It was instant succsess here in my country, so I decided to give away plans for free (first on www.profili2.com). Then I decided to give building support to builders and open building threads on our local RC mod. forum, and here on rcgroups.


Guppy ant its designer (me of course! )

I think, rest of the story is known....

So, now to your questions:
Quote:
Originally Posted by dejfson View Post
1) I assume you made guppy from scratch. How did you design it? What software? It looks like it was originally designed in 3D and acad 2D made from cuts. Was it a google sketchup or similar?
AutoCad in 2D only.

Quote:
Originally Posted by dejfson View Post
2) for your CNC designs: how did you generate 'unfolded' drawings of the fuselage carved bottom? (the one made of 4 balsa strips)
Simple primary school geometry....

Quote:
Originally Posted by dejfson View Post
3) when you designed guppy, how did you estimate where the CG should be? i guess there must be some theory behind, but i do not have clue what to put to google to find that.
CG should stay at point where a lift is situated on model, or better some % forward. There is a static margin necessarry, so CG is placed forward of the aerodynamic centre of the sailplane. nbasically if you place CG at the point where max thicknes of the airfoil is, and that model is slightly inclined nose down, you are pretty close. After some test flights you must feel the plans and set CG to the point, where izt satisfy you. There is a "dive test" also, that shows you if the CG is set to fwd or to aft.

Quote:
Originally Posted by dejfson View Post
I'm asking because I'd like to 'understand' the technology of the design, so next time be able to do my airplane from scratch....
making models from original plans, making models from kits and couple of years of flying them is a base for designing ow models.

It is advicable to design models first in such way, that incorporate well known building methods. Starting with some odd layouts, unconventional materials and design structure details is not a recepy for success.

Regards!

Mitja
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