|Jul 20, 2014, 01:49 PM|
Pak Fa - Full Fuse Pusher: Try and Error Approach
I tried to draw up plans for a PakFa already end of 2012. February last year, I just did quickly a 50 % proof of concept build. Since then, I did not do much about flying or building.
So two weeks agou, when my 8 year old son stumbled into my hobby room, he picked up the PakFa and wanted to throw it around. But first I needed to balance it.
What eventually happened: We did gliding/gc tests, just for fun.
|Jul 20, 2014, 01:56 PM|
So somehow I got the bug. I will build a 100 % version, but I have to play it by the ear.
I have no clue, how to link the control surfaces, where to put the controller, .... so I will take it step by step. The concept I want to follow:
Just building small components, and in the end, it should be just one big puzzle.
My component list:
- front part bottom
- front part top
- turtle deck
- nacelles (upper part)
So last week, I started with just putting most of the components together
Instead of cutting bevels, I just glued in the formers at the correct place, and then was just able to sand the bevel with a sanding block.
Eventually I was surprised, how far I got.
|Jul 20, 2014, 02:02 PM|
So today, I worked some more on the Pak Fa.
Highlight: The nose. It took me longer than expected, but eventually I was happy with it.
|Jul 22, 2014, 03:57 AM|
This time, working on the upper part.
This included cutting, glue and sanding the "upper" nacelles.
My original idea to form the sides went down the drain, since the first part I wanted to bend, just broke.
So I just "doubled" up the front section of the nacelle, but as a side effect, I had no problems to sand it into shape.
The next challenge was to cut out the inner shape of the nacelle out of the turtledeck.
All in all, I'm quite happy so far.
But, I really need to think about the control surfaces - how to connect them. On the outside or via linkage on the inside
Not sure yet. Any comment is welcome !
|Jul 23, 2014, 03:00 AM|
Thanks. It will be a pusher.
I don't think the 100% will be soaring as well as the 50% !
The surface will double("lift"), but the weight will triple. Not that I expect it to be a flying brick - like my avatar
|Jul 23, 2014, 04:11 AM|
Today, I cut out the rudders
Nothing really special, but I had to tinker about the base of the rudders. Took me some time to figure it out, what to glue and how to sand it.
Result is ok.
Next steps: Dremel the elevators. Then it really gets to installing servos, motor, ... and glue the different pieces to one Pak Fa.
Question: I like to paint it like the 055 (see pic). Does anyone know what color they used ? Depending on the pictures I found or articles I read: It's light/dark blue or gray
|Jul 23, 2014, 10:33 AM|
Germany, SN, Dresden
Joined Nov 2008
To choose the right colour, have a look at http://www.mars.slupsk.pl/fort/sukhoi/default.htm
This site is my favorite place to look for colour schemes.
|Jul 24, 2014, 08:14 AM|
Session five: Dremel time
Today was a Dremel day.
Finally I decided to link the ailerons "internally" through a big "Z bend" (or whatever you call it in English). Also dremeled the elevators for the carbon spar. Took me a while to figure out how to place the pieces. Another annoying thing: Setting the depth of the milling head. Half a mm up - no too much - a notch down .....
Except of the cockpit, I don't know what to "construct" anymore. So it is nearing the point, where I have to install the electronics and begin to glue the pieces
|Jul 25, 2014, 03:53 AM|
Session six: Control surfaces
Enjoy your well earned holiday. Not yet eager to come back and put some planes into the air ?
Control surfaces was the theme of today. Where exactly to place the servos, esc ....
One problem I encountered: Since the esc will be placed in the middle of the plane, no airflow there. So I places some air- diverters in front of the serveros to push some air in, and I hope that Bernoulli will suck it out. If it will be enough, we'll see.
Rest is more or less straight forward.
|Jul 26, 2014, 11:21 PM|
Session seven - A: last steps of production
I'm more or less finished with building the different pieces. Most problems I had with the cockpit. (I hate sanding cockpits). I screwed up my first attempt with the traditional layering of pieces.
For the second attempt, I just got the Gripen cockpit out or the waste bin and modified it. I'm not really happy with the final outcome, but if I sand some more on it, I have to place back into the waste bin again.
Now is time to move to the assembly line.
|Jul 26, 2014, 11:30 PM|
Session seven - B: Assembly
I was eager to start with the assembly:
First problem: How to glue the hinges. Eventually I cut small slits into the wing, so I could peel back the depron. Result: No epoxy mess all over the hinges.
By the end of day - ailerons and elevator glued in.
Second problem: elevator does not move. Somehow, epoxy got between the rod and tube. Now I have to figure out, what to do ....
Not a good start
|Jul 29, 2014, 04:11 AM|
Session eight: Servos and bottom part
Glue in the tube:
My thoughts, it must be near the end of the tube and realized it happened while gluing the elevator servo arm. So I just "dremeled" 5 mm of the tube away and that was it.
Then I first installed the servos and linked them. During this work, I was thinking about how to optimize the airflow over the ESC. So I put in some formers to guide the air over the ESC. If it helps ? No clue, but I feel better
Eventually it was time for assembly:
First the nose part and motormount, then the huge bulk with the nacelles and the middlepart. Took me 20 minutes just to prepare everything with UHU por.
Let everything dry out over night.
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