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Old May 16, 2003, 06:59 AM
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nick_cool's Avatar
Argentina, Buenos Aires
Joined Apr 2003
597 Posts
Pulqui II Project

Pulqui II Project

And here we go again, and this time with a complete new EDF model!
After two months of R&D I already have the figures and the draw of my Pulqui II N°5, I am starting to build it next week. I am assuming to spend 6 months in this project.

The initial spec. are based in a modified 1:14th scale:

Wingspan: 800mm, 31.5”
Length: 840mm, 33.7”
Gross Weight: 1112gr, 39.2oz (estimated)
Wing load: 56.5gr/dm2, 18.8oz/sqinch
Airfoil: Symmetrical, 12.4%
Power: 400W
Fan diameter: 92mm, 3.6”

For the people who don’t know the Pulqui II, here are some photos.
You also have a good summary about the history of Pulqui in:
http://www.ipmsstockholm.org/magazin...ile_pulqui.htm
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Old May 17, 2003, 12:14 PM
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Another photo from those days
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Old May 17, 2003, 01:45 PM
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Gordon's Avatar
Braunton, North Devon, England
Joined Aug 2000
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Hi Nick

Danged if I know how you're gonna fit a 92mm fan and cells into a 31.5" span Pulqui II. I began drawing up a 40" span version for a 90mm Midifan some time ago, and here's a pic of the drawing.

There's not a lot of space remaining outside the ducts, even at that size

Gordon
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Old May 17, 2003, 08:42 PM
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nick_cool's Avatar
Argentina, Buenos Aires
Joined Apr 2003
597 Posts
Hi Gordon!
The scale you chose (1:13) is the same I have for the fuse (1:14 modified).
At these sizes there is always a little space for the power plant and RC stuff, particularly in EDF models .

Four ways to gain space:
Choosing a bigger scale e.g. 1:11, but it needs a bigger power plant, is a trade off solution.
Using RC glider’s gear, good if you can afford it
Making the fuse wider, good for me
Cheating the fuse’s shape, awful but practical

I will hide the Rx, battery and Aileron servo in the canopy. The elevator servo will be upside between the rudder and the canopy, and it will be horizontally mounted.

The fan and power plant will as be some where between the CG and the tail. Here we have a compromise, in one hand the fan should be near the tail to be more efficient, in the another hand we have to balance the model (CG) and try to have the smaller momentum we can. The batteries will be then forward the CG and in the lower part, they have to copy the rounded shape of the fuse (customized pack). Or you can put the pack forward the fan’s hub inside a tube. If you have a glow engine, it will be over the CG and the fuel tank behind the engine (beware, to calculate the CG, in this case we have to consider the tank full, because it is behind the CG).

Anyway the accurate position of the power plant should be trimmed with the model in the hands.

Here are the figures for three different scales and the modified ones, all in meters.
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Last edited by nick_cool; May 17, 2003 at 08:46 PM.
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Old May 17, 2003, 09:01 PM
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Argentina, Buenos Aires
Joined Apr 2003
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Here is the RC stuff over the plan.
As you can see my CAD is older than yours
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Old May 19, 2003, 07:03 AM
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nick_cool's Avatar
Argentina, Buenos Aires
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I will construct it all from scratch.

First I cut the wings and the fuse from white foam (20kg/m3) with a hot wire. To do this, I needed to build the airfoils and the fuse shape in balsa cover with ciano in order to admit the hot wiring. I have to admit that it is better to shape in aluminum that in balsa, particularly the airfoils. Regarding the foam, it was the best I could get.

Here are the 3 views of the model I used to cut the foam (hot-wire), the main modification made to this plans was the enlargement of fuse’s diameter, I need 92mm inside plus the RC equipment space.
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Old May 20, 2003, 07:19 PM
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Argentina, Buenos Aires
Joined Apr 2003
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I covered the foam with pre-molded glass fiber + epoxy the wings. I pre-molded the fiber glass in a window glass. Summarizing, cut the fiber, covering the window glass with the epoxi and after that put the fiber. Wait until the epoxi gets no liquid and put the lamina over the foam which should wetted with epoxi.

Previously I practiced the same technique with the rudder. Very good idea!
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Old May 20, 2003, 07:21 PM
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Argentina, Buenos Aires
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Here is a photo taken last sunday
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Old May 22, 2003, 07:55 PM
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Argentina, Buenos Aires
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Another one
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Old May 26, 2003, 07:14 PM
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nick_cool's Avatar
Argentina, Buenos Aires
Joined Apr 2003
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Oh, oh!

I finished to cover with fibra a half wing, and after the cure, I realized is not ok.
I should leave the epoxi drying for more time next, the wing surface is waved.
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Old May 27, 2003, 12:41 AM
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monkamarm2000's Avatar
NorCal Silicon Valley
Joined Aug 2002
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I dig it. I'd like to make that plane in a glass version. It's like a Mig 21 without the cone.

Barry
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Old May 28, 2003, 06:27 PM
2014 EDF JET JAM We be Jamming
Kevin Cox's Avatar
St. Louis Intl, Missouri, United States
Joined Jan 1997
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While going through my FS2002 aircraft list, look what I found.

Rotating
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Old May 28, 2003, 06:28 PM
2014 EDF JET JAM We be Jamming
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Gear going up
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Old May 28, 2003, 06:30 PM
2014 EDF JET JAM We be Jamming
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St. Louis Intl, Missouri, United States
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It is time to buzz the tower
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Old Jun 02, 2003, 08:29 PM
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nick_cool's Avatar
Argentina, Buenos Aires
Joined Apr 2003
597 Posts
Yesterday I finished to cover the second half wing. As the first was bad, this time a tried a different mix. I used 2 parts of epoxi for each part of fiber (48g/m2). This time I think it would be great, for this low weigh 1 to 1 proportion is too few epoxi.
I will try to take some photos for the next post.
Great landings!
PS thanks Kevin!
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