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200% Duster build

EraJomppa

RC Enthusiast
#1
Here goes, I will be doing this as a part of a bigger project (Link 1, Link 2), but Ill post the plane building process here.

I got the plans from a fellow user nerdnic (he has a thread about his scaled plans). I printed them on A3 paper and cut the wing template out. I didn't print the bottom wing since it was practically just a rectange, so I just traced in on the depron. I now got both wings cut out, beveled and ailerons cut out ready.

I also didn't cut any holes for servos and pushrods, since I don't yet have the servos I'm going to use. I will be ordering them from hobbyking soon. I haven't yet decided if I want to install flaps on this plane. It will not be used for any serious aerobatics and I'v seen the roll rate :D I think that if I cut the ailerons in half and made flaps off of them it would still have a lot of authority on roll. But I'v seen how slow 125% size flies, so I don't know if 200% version need any slowing down ;)

Tomorrow I will buy some 12 mm aluminium tubes to go in as wingspars and will build the wings. After that I will focus my attention to the fuselage. I will want to use the finished wing profile to trace the holes in the fuselage, since I am using depron in this build and it might cause the airfoil to be slightly fatter/thinner in some places, especially since the material thickness is 6 mm.

Here are some pictures of the wing so far, I was amazed of how big (and fat :p) they actually are:
2014-05-29 12.11.13.jpg
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PS: I thought I was gonna be able to build this out of one 2500 mm x 800 mm x 6 mm sheet. How wrong I was... :D
 
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EraJomppa

RC Enthusiast
#2
Also you can see that I will include some undercamber in the wingtips. Total length of one winghalf is 750 mm and the bottom layer is 600 mm long so that leaves 150 mm of undercarmber. We'll see how that works out.

And as I said I will be using 6 mm depron, instead of 4 - 4,75 mm thick DTFB. Also I'm using scaled up plans and the plans use a lot of FT techniques that can only be applied to DTFB. So I'm mostly keeping the shape of FT Duster, but the building techniques, I mostly just wing it :p I got great many plans, but they are not really put on paper, but I will post them and explain my processes when I build along.
 

EraJomppa

RC Enthusiast
#3
For example, the leading edge is done by cutting the winghalf in two pieces, then taping the leading edge from one side with strong packing tape. Then I did as per FT plans and made a double bevel.
2014-05-29 15.36.58.jpg
2014-05-29 15.37.06.jpg


The ailerons have the same treatment, but bevel only on aileron and packing tape on both sides.
2014-05-29 15.37.30.jpg
 

EraJomppa

RC Enthusiast
#5
;) Me too, this will be a blast! Both to build and fly I can imagine.

I now got the tail and wings cut out and taped/hinged. Getting to see how big this will actually be! :eek:
2014-05-29 22.51.46.jpg
2014-05-29 22.51.56.jpg

About the tail section; I cut out the pieces and hinged them with strong clear packing tape. Bevel on the horizontal stabilizer, but on vertical stab I figured the rudder has more area to cut out from. For the elevator I decided extra strengthening was needed, but due to a lack of laser cutter and extra plywood, I went with a 5 x 1 mm carbon fiber spar. I cut a snug hole on both elevators and it now snaps on perfectly first time, every time. Kinda handy when gluing I guess? No extra support on rudder, at least not yet.
2014-05-29 21.52.05.jpg
2014-05-29 21.52.21.jpg

Nothing is glued yet.
 

nerdnic

nerdnic.com
Mentor
#6
Looks great so far man. I think you're onto something with cutting the ailerons down and make flaps. You'll still have a crazy roll rate even with only 50% area.
 

EraJomppa

RC Enthusiast
#8
Or mix in your flaps so they can be ailerons too ;)
Yeah, but I don't think I want to do that, there is a chance of stalling the whole wing if you extend the flaps all the way. With separate flaps, the wing will first stall near the root and you would still have aileron control. That's my reasoning at least ;)
 

EraJomppa

RC Enthusiast
#9
Okay, I will be putting the 12 mm aluminium spars to the wing today. I had to go and buy a new hot glue gun since my old one was looking a little beat up, the glue was spreading from each gap of the gluegun.
2014-05-30 18.47.21.jpg

Here's the new gluegun and a bunch of new hot glue for that matter, a whole kilo of it! :D Ought to last for a while.
2014-05-30 18.47.30.jpg
 

EraJomppa

RC Enthusiast
#10
Here's the idea of the spar I had. It's 24 mm high + 12 mm of depron on top and bottom = wing total height is 34 mm. The spar is a bit lower than the plans would suggest, but the 6 mm depron skin makes it as high as the DTFB plans would suggest.

The aluminium spar is 12 mm outer diameter (1 mm thick wall), the lower depron spar is 12 mm, the same as the alu spar. The side depron spars are 18 mm high so the total top height with the aluminium is same. Then one layer of 24 mm depron spar that makes a total of 24 x 24 mm spar. Ought to do nicely. This is the first version so there are no slots that would make it easier to put together.

This spar is slightly thicker than the original spar on the plans which is 2,54 mm high and 18 mm thick, but it should work just as well.

Now to heat the hot glue gun.

2014-05-30 22.14.55.jpg
 

EraJomppa

RC Enthusiast
#11
Got a lot done today, the depron pieces have turned into a object that resembles a plane :)

I started with the wings, I traced where the spars would go and glued the first, middle one.
2014-05-31 12.30.46.jpg

Since I didn't have any holes cut out to help with the alignment I used spare depron pieces.
2014-05-31 12.35.18.jpg

Test fitting the spar.
2014-05-31 12.51.39.jpg

One spar finished. Crude looking but works.
2014-05-31 12.57.00.jpg

Here are both wing spars finished.
2014-05-31 13.13.00.jpg

I added the extra piece near the trailing edge to make the airfoil resemble the original, this is copied from the FT spitfire and it's monster version (Original has one of these, the monster has 2, so I went with one since the original doesn't have any). I don't think it is essential, but I doubt it is a bad or the wing either.
2014-05-31 13.15.29.jpg

Here you can see the airfoils. The depron doesn't bend like DTFB so a little different airfoil was to be expected. I used these to trace an appropriate holes for the wings to the fuselage sides. Even though they came out different (from DTFB), they are both made exactly the same and are identical.
2014-05-31 13.29.54.jpg

Oddly enough I may have accidentally gained some polyhedral to the wingtips? Might be the folding technique or the tape on top or both. Anyways, it appears that both wingtips are again identical and the aileron are straight so no harm in having them like that.
2014-05-31 13.30.04.jpg

I cut out the fuselage sides and bottom piece and taped them together to see what the plane will look like ;) It's huge! My better half is there for a size comparison. The tail pieces are not yet glued at all.
2014-05-31 16.21.26.jpg

Wing is now glued. I put healthy amount of 5 minute epoxy near the aluminium spars. Then laid a lot of hot glue and set the dihedral. Hot glue held the wing in place for the epoxy to cure. I had planned that I would laminate some glass fiber or carbon fiber cloth around the wing join, but it seemed so stiff that I just used some heavy duty tape around it.
2014-05-31 17.47.53.jpg

Taking it's shape, looks gorgeous! And huge! The small 4240 motor I got in store for it looks way too small for it :p
2014-05-31 18.22.56.jpg

Making the fuselage box for reinforcement. This time with slots, they help a lot with the assembly.
2014-05-31 18.51.38.jpg

Test fitting the box.
2014-05-31 19.33.21.jpg

I got the fuselage box glued in place and it's curing right now. I will next glue the tail pieces together and glue the tail in place.

PS: the top piece of the fuselage box is not glued it so that I can access the insides of the plane after I got the wing and tail mounted.
 

EraJomppa

RC Enthusiast
#12
Well, I glues the tail pieces and attached the tail in place and glued it down. Put couple of spacers inside the tail, since it seemed too flimsy without them. I'm leaving the rudder last since once it's in place, I cant put the plane flat upside down on the table, which is really handy.

Also I glued the wing on and cut it out again. I need to reinforce few of the places and maybe add a guiding block of a sort there to keep the wing straight.

2014-06-01 01.48.06.jpg
2014-06-01 01.48.19.jpg
 

EraJomppa

RC Enthusiast
#14
More progress. Mostly reinforcing the wing saddle area.

Made reinforcements to the front using plywood and 10 x 10 mm wood dowels in the rear.
2014-06-01 12.51.42.jpg
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I put some extra foam to reinforce the area. I wouldn't want to leave unsupported area separating the fuselage from the tail, that would be an obvious weak point.
2014-06-01 13.12.15.jpg

Put some carbon fiber rods as rubber band mounts. Both should be well supported by the wood parts. I will put some hot glue and secure them in place once I'm happy with everything.
Also you can see that I added one depron layer to the rear wing area. This was where my airfoil didn't quite meet the hole I made for it so I put some foam there for the wing to sit on properly.
2014-06-01 13.18.45.jpg
2014-06-01 13.18.54.jpg

Here's how it all looks like with the wing on.
2014-06-01 13.21.01.jpg

I put some of the electronics I have already inside and attached the rudder (no glue) and weighted it. 1500 grams. I was amazed. Even though I'm missing few servos, electronics, landing gear, foam layers and reinforcements, I was sure I was close to 2 kg. This might mean that I might get it close to 2 kg, which in my book is really light for a plane this size!
2014-06-01 13.31.02.jpg
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And did I mention, it's HUGE! and I'm not a small fellow at 188 cm ;)
2014-06-01 13.32.25.jpg

PS: I forgot to make the alignment pieces, gotta go make those now-->
 
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EraJomppa

RC Enthusiast
#16
More progress. I went to the local hobbyshop and got some of the stuff I need. I still have to buy some plywood. I also ordered 4x of these 38 gram servos. I have 2 standard servos but I have yet to decide whether I will make the flaps or not.

Anyway what I achieved today:
I finally decided that the wing mounts were good and glued them in place, I put some depron to the leading edge side to further support it.
2014-06-03 00.43.01.jpg

Added a tail wheel, rudder is still not attached.
2014-06-03 00.43.14.jpg

Made the main landing gear from 1/8" thick (3,18 mm) metal wire. The wheels are comically small at the moment since these are just ones that I had laying around. I will eventually put bigger wheels.
2014-06-03 00.43.59.jpg

Wing bottom is strengthened against the rubber bands and landing gear with coroplast/coreflute or whateverit'scalled.
2014-06-03 00.44.43.jpg

This stuff..
2014-06-03 00.44.47.jpg

And here is how it all fits together. The landing gear is removable this way and is held in place by the rubber bands. Also the gear is angled forward so that it will create a sort of seesaw effect and the rubber bands will actually also act as shock absorbers during landings. I will still need to adjust the stiffness of the rubberbands to and maybe wrap them around the landing gear once etc. to get proper amount of stiffness and elasticity.
2014-06-03 00.46.30.jpg

Here is a closeup of the landing gear. I want to make sure that the landing gear wont pop off under the rubber bands so I might want to wrap the rubber bands around it or something.
2014-06-03 00.46.34.jpg

Standing on it's own ^^
2014-06-03 00.47.13.jpg

And with a tail and motor it is starting to look like a plane!
2014-06-03 00.50.01.jpg