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Oct 26, 2014, 12:05 AM
Registered User
Build Log

Scale Build Off 4 - Quest Kodiak 100 1/10th scale


I've been wanting to build a Kodiak for a while now, but despite a few folks talking about it here and there on the boards, no one seems to have completed one, and there certainly aren't any kits that I've been able to find. So here goes for my first scratch build from the ground up...

More info about the actual aircraft here - it's got a neat bit of history:
http://en.wikipedia.org/wiki/Quest_Kodiak

... and for more pretty pictures of the real aircraft (the pic of the yellow/white one here came from this gallery):
http://questaircraft.com/media-galle...oto-galleries/

Final specifications:
~1/10th sport scale
Wingspan: 54in / 1.37m
Wing area: 390 sq in / 0.2516 sq m
Weight: ~63.5oz/1800g AUW (52.9oz/1500g less battery)
Wing Loading: 23.4oz/sqft / 71.54g/dm2
Cube Loading: 14.2
Airfoils: Inner section - NACA 2412, Outer section - Clark Y
Motor: AXI 2814/16 ~300W (with heatsink mod; see https://www.rcgroups.com/forums/show...3#post33633414)
ESC: Advance 40 Pro SB
Battery: 3S 4000mAh
Propeller: Master Airscrew 10x7 3-blade

Maiden flight video:
https://www.rcgroups.com/forums/show...1#post33688256

Photos of the model:
https://www.rcgroups.com/forums/show...&postcount=171

Plan requests:
I have created a rough set of plans for the model; a builder with intermediate skill should be able to follow them. PM me if you would like a copy.
Last edited by matheweis; Apr 25, 2016 at 01:36 PM.
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Oct 26, 2014, 03:55 AM
Slip the surly bonds...
Sopwith Mike's Avatar
Hi Mathew,

By coincidence I have been looking at the Kodiak and gotas far as sketching out the basic structure for a 47" span version (1/12th). Like you, I thought a lightweight structure without the scale flaps etc, but including the NACA cuff on the outer wing sections.

Do you have a decent 3-view? I haven't looked very hard, but there doesn't seem to be one on the sites I normally use, although there is a rather basic one on the company literature. I though I might add the floats as an option.

The picture is of Ivan Pettigrew in a Kodiak the other day.

Mike
Oct 26, 2014, 04:28 AM
Registered User
aeropylot's Avatar
Funny...I started a Quest Kodiak years ago but lost the files. I started a redraw awhile ago and was looking at this one too. I was doing 1/10 scale....good luck....they are great looking planes and built in my state. In fact I see them weekly at my airport.
Oct 26, 2014, 12:24 PM
Registered User
Quote:
Originally Posted by Sopwith Mike
Do you have a decent 3-view? I haven't looked very hard, but there doesn't seem to be one on the sites I normally use, although there is a rather basic one on the company literature.
Not sure if this is the one that you're referring to or not, but there is a pretty good 3-view in the Pilot's Operating Handbook for the Kodiak (attached a snapshot of the relevant page).

There are plenty of other mid-to-high resolution side views on the site, for example:
http://questaircraft.com/the-kodiak/exterior/

Also, there is a "factory authorized" module for FSX by Lionheart Creations. So if you have FSX, that makes for unlimited viewing angles. http://www.lionheartcreations.com/Kodiak.html ( I don't have FSX, but this looked like a very good source ).

Finally, someone by the name of 'antipode77' uploaded a fairly good 3d model of the Kodiak on the Trimble Sketchup site:
https://3dwarehouse.sketchup.com/mod...18a2bd5aa39c80
As a quick warning, it does seem to have some inaccuracies when getting down to detail, for example it is missing the engine cooling scoops, and the rudder control surface is off by a bit, but as far as basic dimensions go, it looks quite good.

Quote:
Originally Posted by Sopwith Mike
I thought I might add the floats as an option.
That would be really spectacular, but as I have zero experience with floats, I didn't want to take on too much at once. There's even a couple of lakes nearby, and it snows in the winter here too, so I'll definitely have to built the fuselage with a future set of floats in mind.
Last edited by matheweis; Oct 26, 2014 at 12:33 PM.
Oct 26, 2014, 01:48 PM
Slip the surly bonds...
Sopwith Mike's Avatar
Thanks Mathew,

I have seen most of the stuff you refer to. Ther are some really good side-on photos on the web so I will use the factory 3-view as a basis and develop the drawings via the photos. I have emailed the company to see if they have anything better.

I'll start a build thread when I've finished the current project and I'm subbed to yours.

Mike
Oct 26, 2014, 09:49 PM
Registered User
Here's a rough draft of the wing (in red on the upper half of the image). In white below that is the true scale wing. I've upped the chord from approx 6.8in to 7.5in, giving me just over 10% extra wing area. I think that may come in useful later on... wing area is at 391.25 sq in, vs approx 350 sq in at true scale.

The second image is where the airfoils switch between the mid and outer wing sections. The NACA 2412 and the Clark Y end up creating the faux "cuff", as well as building in a nice washout on the outer panels.

"Fake" fowler flaps seem do-able at this scale without too much extra weight, so I'm going to give them a shot. Something like these:
https://www.rcgroups.com/forums/atta...mentid=4050312

Construction is presently targeted to be 1/16inch ribs, top and bottom 1/8x1/4 spars with 1/16 shear webbing across the front and back of entire midsection, and 1/32 sheeting over the leading edge. The center of the midsection will be fully sheeted. Intuitively it feels like the dihedral at the center may lack reinforcement, so I may change this up a bit. Otherwise I'm pretty happy with this direction so far.
Oct 29, 2014, 12:52 AM
Registered User
Here's a rough draft of the tail fins. The stabilizer I'm very happy with and I'm calling it good. It comes it at exactly 24" at scale. I might even get lucky and be able to completely hide the control horn by attaching an arm to the torque rod.

That is one fat rudder! Makes for an interesting hinge point. I've never done one this fat before, so I need to think about it for a bit.

Fuselage is up next while I think about the rudder. I found a nice cross-section of the cabin on page 7-59 of the operations manual.
Oct 29, 2014, 06:20 AM
Slip the surly bonds...
Sopwith Mike's Avatar
Looking at various photos, the sides of the fuz don't seem to bow out as much as in the cross-section, but this may be just my imagination. I'm going for a semi-scale flat sided cross section. I plan to model the very obviously curved edges with 1/2" triangle stock top and bottom.

Nice construction drawings!
Last edited by Sopwith Mike; Oct 29, 2014 at 07:17 AM.
Oct 30, 2014, 12:13 AM
Registered User
Quote:
Originally Posted by Sopwith Mike
Looking at various photos, the sides of the fuz don't seem to bow out as much as in the cross-section, but this may be just my imagination.
Have a look as this photo (clearly marked as all-rights-reserved, or I'd upload it), I think the open door shows the curvature pretty well.
http://www.flickr.com/photos/corpora...nt/7172894992/

... but yea, I hear ya, it gets pretty hard to tell the difference between lens distortion and curves after staring at the photos of this plane for a while.

Quote:
Originally Posted by Sopwith Mike
I'm going for a semi-scale flat sided cross section. I plan to model the very obviously curved edges with 1/2" triangle stock top and bottom.
I may regret not following in the footsteps of the masters and doing something similar

Quote:
Originally Posted by Sopwith Mike
Nice construction drawings!
Thanks!
Oct 30, 2014, 12:57 AM
Registered User
Here's a quick progress shot on the fuse drawings, as I'll probably be out of commission for the rest of the week and weekend... these are not at all complete. Some general notes:

* This thing is a huge box at scale; ~6.5in tall, ~5.5in wide.
* Framing is out of 1/4x1/8 bass and 1/8x1/8 balsa (the latter primarily for sheeting support)
* Formers out of 2 cross-grain layers of 1/16th balsa, except A, C1, and C3 - these will be plywood.
* The bottom between C1 and C3 will also be plywood, for main gear support.
* The fuse will be fully sheeted, mostly 1/16, except 1/8 around the windows (the curvature will sand most of that down to 1/16th), and 1/4 on the bottom sharp edges.
* Battery hatch will go between B and C on the bottom.

Other misc thoughts:

Motor shown up front is the AXI 2814. Perfect motor if the plane sits in the 3 - 3.5lb range... and I really should stick to the low end of that with the wing area of 391.25 sq in.

The main air scoop will be functional for cooling the motor.

The scale sizes of other parts are coming in just perfectly:
Spinner at 1.75 dia
Main gear wheels at 3in dia
Nose gear wheel at 2.25in dia

Fully contrary to the weight discussion, I'm eyeing grinding down the struts on one of these mains to use for the nose wheel:
https://www.hobbyking.com/hobbyking/...Class_3pc.html
Oct 30, 2014, 05:07 AM
Slip the surly bonds...
Sopwith Mike's Avatar
Nice work on the fuselage. My (simplistic?) take on the top view is that there is a straight taper from your former D to the tail, and forward from your B to the spinner ring. It makes building easy!

Might I comment on your wing design? By reference to the 3-view, your outer section seems too broad at the tip. I think the sweepback is slightly more pronounced - the tip is as far behind the centre section LE as the cuff is in front of it, and the shape of the tip is different. I'm sure you have this in hand!

There's an interesting view of the wing in the two pics I lifted off the internet - who would have thought that the aileron had an endplate? And sub-fins on the pannier-equipped green one?

There are some really good colour schemes - the tiger one might be a bit tricky!
Oct 30, 2014, 10:58 AM
Registered User
Quote:
Originally Posted by Sopwith Mike
Might I comment on your wing design? By reference to the 3-view, your outer section seems too broad at the tip. I think the sweepback is slightly more pronounced - the tip is as far behind the centre section LE as the cuff is in front of it, and the shape of the tip is different. I'm sure you have this in hand!
Oh dear, I had not noticed! Of course you are right. And now I see that my tip design was quite off as well. Here is an improved design.... is there a better way to create the tip than carve it from a solid block of balsa?

Quote:
Originally Posted by Sopwith Mike
There's an interesting view of the wing in the two pics I lifted off the internet - who would have thought that the aileron had an endplate? And sub-fins on the pannier-equipped green one?
There are funny little fins all over this plane. I still do not understand the purpose of the little winglet on the rudder... I asked my brother (who is a pilot), who thought perhaps it had some effect on the prop wash, but he wasn't sure.
Oct 30, 2014, 11:03 AM
Registered User
Quote:
Originally Posted by Sopwith Mike
There are some really good colour schemes - the tiger one might be a bit tricky!
If too complicated, there is always this black one...

... or perhaps the factory primer job.
Oct 30, 2014, 04:17 PM
Slip the surly bonds...
Sopwith Mike's Avatar
I love the way the wings of the primer prototype are held on with duct tape
The float versions have two options for extra fin area: a large sub-fin or two plates on the elevator...then there's the plate below the clamshell door, various aerials...what fun. No wonder there isn't a decent 3-view of the plane!

The more I look closely at the pictures, the more I like the plane. There's a chance of getting a flight in one out of Abbotsford BC next May - fingers crossed.
Oct 31, 2014, 12:51 PM
Registered User
aeropylot's Avatar
Looking great.....


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