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-   -   Build Thread; Mountain Models QF-2 DLG (https://www.wattflyer.com/forums/showthread.php?t=36439)

Sky Sharkster 07-02-2008 12:03 PM

Build Thread; Mountain Models QF-2 DLG
 
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Hello All,
This will be a build thread of the Mountain Models/Laser Arts "Quick Flick 2" Discus Launch Glider, designed by Paul Daniels.
http://www.mountainmodels.com/produc...4fea24f171ca7d
The kit is very complete, all laser-cut balsa, carbon fiber ribbon, pushrods, Avia Sport c/f boom, fiberglass cloth, full size plans and a detailed photo + text instruction booklet.
Hope you enjoy it!
Ron

Here's the kit contents and the beginning step, the nose pod doublers;

smokejohnson 07-02-2008 12:14 PM

Subscribed :)

Murocflyer 07-02-2008 12:37 PM

Me too! I have a Gambler DLG but considered this one also.

Watching closely.

Frank

Sky Sharkster 07-03-2008 11:29 AM

Next Step, Supplies
 
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Hello James + Frank, Glad to have you along!
The next step is adding formers 2, 3, 4, 5 to one side piece. The laser-cutting is so precise these pieces are sitting in their slots with no glue or pins.
You can also see the instruction booklet page; Most of the photos will be the same as I'll have here.
They describe 3 methods for finishing the sheet tail surfaces; Fiberglass cloth (supplied in kit) and F/G resin, F/G Cloth and Minwax Poly or F/G Cloth and CA. I'll be using the Minwax, picked up a can yesterday, as well as more Titebond. I use the big bottle to re-fill my small "applicator" bottle.

Sky Sharkster 07-04-2008 11:03 AM

Nose Pod, Doublers
 
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Here's the 2nd side glued to the bulkheads, added F-1 (front) then the 2 F-6 doublers. I used Titebond for this, more drying time to position the doublers.

jb48 07-04-2008 11:26 AM

I`ll follow this thread with great interest, especially that I received the plans sheet yesterday. At this time, I hesitate between scratchbuilding, short kit building or full kit building. Thanks Ron.

Sky Sharkster 07-04-2008 11:46 AM

Choices?
 
Hello JB,
Well, I like to scratch-build also, but there's no way I could cut the parts this accurately! The wood is perfect for the applications and the laser-cutting is amazing, everything just fits so well.
I'd guess the short kit would be a good bet, since it's the cutting that takes time. But the full kit includes the F/G boom, F/G cloth, strip stock, nice thin and light pushrod/tube assemblies and C/F ribbon. If you don't mind hunting down all these parts separately, the short kit might be the way to go. But overall, I believe the full kit is a better deal.
Anyway, good luck, keep us posted!
Ron

Sky Sharkster 07-04-2008 03:15 PM

Nose Bottom Sheet
 
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A bit more work, the nose bottom sheet. It has lines inscribed to match up with each bulkhead, very handy.
First I sand the bottom of the pod structure flat by running it across 180 grit sandpaper flat on the board. The black marks on the 'paper are from the laser "burn" of the wood.
Applying glue, that's Titebond in the small bottle. I use toothpicks to spread it evenly. Just a thin coat!
Pins at the open spaces, rubber bands near the bulkheads so they don't squeeze or deform the structure. Done!

Sky Sharkster 07-04-2008 06:45 PM

A Minor Problem
 
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I ran into a snag on the next few steps, it my have been a case of my not understanding the directions correctly.
Steps 8 + 9 in the booklet show two 1/4" balsa pieces placed alongside the boom at the rear (inside) of the pod. Then 2 -1/8" balsa pieces (F7 Doublers) are placed vertically on the sides. Although the photos are clear enough, the fact is a round boom doesn't mate up with the flat ends of the 1/4" pieces very well. When the 1/4" pieces are placed in the bottom, the boom won't fit in. I tried them angled, sideways, still didn't work. It seemed obvious to me that the inside faces of the 1/4" pieces needed to be sanded to a concave shape to accept the boom, but this isn't mentioned or shown anywhere.
It was no problem to sand the concave shape, I just wrapped 180 grit garnet paper around the boom and shaped the inside surface (see photo).
But I was suprised this wasn't described in the instructions. Again, I may be misunderstanding something somewhere.
The boom is not glued in at this time, it is just used to align the pieces.
If anyone has run into this or knows the correct method, please let me know!
Ron

Sky Sharkster 07-04-2008 10:51 PM

Triangle Stock, Nose Pieces
 
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A bit more work, several sets of triangle stock for bracing, the 2 sets of wing mount pieses and the (5) laminations of 1/4" balsa that make up the nose piece. Here again I used wood glue, so there would be time to align each piece.

smokejohnson 07-04-2008 11:00 PM

It's looking good Ron.

jb48 07-05-2008 12:29 PM


Originally Posted by Sky Sharkster (Post 436267)
I ran into a snag on the next few steps, it my have been a case of my not understanding the directions correctly.
Steps 8 + 9 in the booklet show two 1/4" balsa pieces placed alongside the boom at the rear (inside) of the pod. Then 2 -1/8" balsa pieces (F7 Doublers) are placed vertically on the sides. Although the photos are clear enough, the fact is a round boom doesn't mate up with the flat ends of the 1/4" pieces very well. When the 1/4" pieces are placed in the bottom, the boom won't fit in. I tried them angled, sideways, still didn't work. It seemed obvious to me that the inside faces of the 1/4" pieces needed to be sanded to a concave shape to accept the boom, but this isn't mentioned or shown anywhere.
It was no problem to sand the concave shape, I just wrapped 180 grit garnet paper around the boom and shaped the inside surface (see photo).
But I was suprised this wasn't described in the instructions. Again, I may be misunderstanding something somewhere.
The boom is not glued in at this time, it is just used to align the pieces.
If anyone has run into this or knows the correct method, please let me know!
Ron

Hi Ron, If you go to pldaniels.com/flying you`ll see that Paul Daniels has written a 76 pages QF-2 construction manual (in pdf format) that you can download. He explains very well (text and pictures) that you must sand a kind of channel for the cf rod, exactly as you did.

Murocflyer 07-05-2008 12:45 PM

Wow, that looks might sturdy.

Nice work so far Ron.

Frank

Sky Sharkster 07-05-2008 05:54 PM

Tail Surfaces, Minwax, Mylar
 
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James + Frank, Thanks for the support!
Jb, Thank you for the link, you're right, it's much more complete than the booklet. It uses some of the same photos, also. I'm relieved I didn't screw up the boom-attachment blocks!
Going "by the book" the tail surfaces are next. First a sanding with 400 paper, add a 4" carbon ribbon to the center of the elevator, then cut out the 1/2 oz fiberglass cloth on a bias, according to the included drawings.
Next I found a long mylar bag, must have been a model wing packing. Pretty thick material, roughly twice as thick as Monokote backing sheet. I split it lengthwise, now I can lay the tail piece on one face of the inside, apply the Minwax and fold the other half of the mylar on top of the work.
In the second photo there is cloth on both sides of each piece, but no adhesive.
Last photo, cloth and Minwax on the stab/elevator, then put the mylar over it. After that I smoothed out the cloth with a straight edge and placed a few magazines on top for weight.

Sky Sharkster 07-05-2008 07:13 PM

Back To The nose Pod
 
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Here I have to skip around a bit; The next steps involve the completed tail, boom, etc. Well, the tail is drying and I want to keep working!
So, I went to page 11 and the next part of the nose pod construction. Add the 5-lamination balsa nosepiece, tack the 3/16" balsa hatch on, carve to shape. My favorite job, carving and shaping balsa! Seriously, it's fun and you can make a big mess...what could be better?
(1) Nose piece glued on
(2) Hatch tacked on
(3,4) My favorite tool in modelling, the razor plane. Master Airscrew makes this one, had it for years.
(5) Ten minutes of planing, it's starting to shape up.

Sky Sharkster 07-06-2008 01:42 PM

Tail Surfaces, Pt 2
 
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I removed the magazines and peeled off the mylar. It's very smooth, dried in slightly less than 24 hours.
Trimmed the overhang, 2 photos, first one without flash, 2nd one with flash.
Applied F/G cloth and Minwax to the other side
Mylar over the top, magazines and drying next.

Sky Sharkster 07-06-2008 11:27 PM

Fin/Rudder, Nose Shaping
 
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I managed to get a couple hours work in today, before going flying.
Here's the Fin/Rudder, first the (dry) covered side, then the second side with F/G cloth and Minwax freshly applied.
Then, more carving (planing, really) and sanding on the nose. First 120 garnet, then 180, last 400 wet-or-dry.

smokejohnson 07-07-2008 12:14 AM

When I have used FG cloth with WBPU on foam I would put a layer on the foam and then lay my cloth on the wet surface. Then I would spread some more WBPU around to saturate the cloth and make sure it was laying flat and then leaving it to dry. Is there any disadvantage to using the same method on balsa? Will it wrinkle if you don't put weight on it?

The pod is looking good BTW.

Sky Sharkster 07-07-2008 10:28 AM

Minwax Application
 
Hi James,
I've tried the Minwax/cloth application both ways, and it definitely works better the way you described, adhesive first, cloth on top, then another coat to saturate. Sorry I didn't make this more clear.
The QF II instructions recommend the mylar over the application and this is the second time I've tried it. Works great! After the top coat of Minwax I blot up the excess with TP, then lay the mylar over the surface. Next I smooth out the mylar with a straight edge (small ruler). The magazines are an addition I read about in an article on F/G foam wings, seemed like a good idea. No air bubbles or wrinkles and the surface comes out very flat. I guess it works like a poor mans vacuum-forming!
Thanks for the interest, I'll be posting more soon.
Ron

Murocflyer 07-07-2008 11:22 AM

Looking good Ron. This is one of those builds where a lot of different building skills are used. Do you think you are in your target weight goal? When building mine, I was afraid of getting too heavy during my build. I was concerned about strength as mine felt weak. Yours looks more sturdy then the Gambler.

Frank

Sky Sharkster 07-07-2008 11:49 AM

QF-II Weight
 
Hi Frank,
Yes, this seems like a strong build, and you're right about the different skills, balsa, carbon fiber, F/G cloth, everything but foam!
I hope to hit the RTF weight (range) listed by MM. It's 6.5 oz to 7.5 oz. The wing area is 1.88 square feet, for a wing loading of 3.46 to 4.0 oz/sq ft.
My experience with building is that the biggest factors in weight build-up are wood selection, glue weight and finishing/covering. Since the wood is provided (and seems to be right for its intended application) and the covering weight is fixed (assuming you use the recommended type and brand) the adhesive weight is the main variable. For tight-fitting joints, one drop of CA from a thin applicator tip is plenty. No epoxy (yet), it's the heaviest adhesive. Wood glue like Titebond, used sparingly seems to be the lightest and is strong enough for most applications.
Also, I'll be using the recommended servos and battery, so my RTF weight should be in the ballpark. I'll know a little better when the tail surfaces are dry, they list a weight range of 9-12 grams for the entire tail, after finishing.
Ron

smokejohnson 07-07-2008 12:07 PM

I see Ron, thanks.

Sky Sharkster 07-07-2008 01:44 PM

Prepping The Wing Construction
 
8 Attachment(s)
Since the tail surfaces aren't dry and I have a couple of hours before work, thought I'd start on the wing. This is also out of sequence.
The dihedral braces are built-up from a balsa/carbon fiber/balsa lamination. There are 2 main braces, each one is made from 1 piece of 3/32" balsa, C/F, 1 piece of 1/8" balsa.
The photos should be self-explanatory, they recommend clamps for the final step but the pieces kept sliding out of alignment so I used "T" pins with pin clamps, after I wrapped the shrink wrap around everything. Seems to hold OK.
They also recommed 30 minute expoxy, and that's just barely enough time. The epoxy was already starting to stiffen or jell as I got the 2nd piece assembled. Work fast!
Ron

Sky Sharkster 07-08-2008 12:14 AM

Starting On The Wing
 
6 Attachment(s)
I got home a bit early and began the wing construction.
First, I peeled off the cling wrap from the dihedral doublers and cleaned up some of the epoxy that had bled out, then I gave 'em a quick sanding.
Next I laid out the wing ribs (without the bottom sheeting) to make sure everything was accounted for; A few ribs had fallen out of the laser-cut sheets. Sure enough, all there!
Laid the bottom sheeting in place and applied Titebond to the bottom spar.
Spread out the Titebond evenly.
Pinned the spar in place, pins in front and through the rib slots, no extra holes.
Both wings have spars added to sheeting.

Sky Sharkster 07-08-2008 11:58 AM

Ribs, Right Wing
 
5 Attachment(s)
Here's the ribs pressed (not glued) in place, right wing. Although I was careful to try aligning the back of the spar evenly with the rear of the sheeting, in a few spots it drifted slightly while drying. A whisk with the emery board to widen the spar slot on these ribs lined everything up again.


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