Hi all I've nailed down my next project and decided to document it all here, start to fin!
What we have here is the Multiplex Pico Stuntman. Now, don't all crowd around at once! This is a rather obscure plane and I think is out of production now. I'm not sure if it was ever available in the US but if someone chimes in with some history I would appreciate it!
I got it on eBay with a BM2410-12 brushless motor which should be sufficient. I am thinking I can get away with a cheap 10A ESC, but I'll deal with the power train later. No clue what prop will be good...
Also of interest, I have an AR6000 receiver slated for this model. It will be interesting to program my DX6 to get this bird to fly well.
Out of the Box
My first impression, after having built and flown the Multiplex Minimag, was "Uh Oh!! This is not Elapor! This is some kind of frail thin foam!"
This is only my second attempt at building a plane kit. The Minimag stretched my newbie abilities to the max (I had to re-build it after I found it was too heavy and unbalanced), and I plan on using my new skills here, but am not entirely confident at this point.
Undaunted, we continue! Glory or shot down in flames!!
The instructions seem sufficient. The Minimag docs (and way cool assembly video CD) are way superior, but this is an older kit...
I can already see some stuff in the box I won't use. The stock wheels for one. Not sure if I like their ailerons - I may go to balsa.
So, be patient and travel with me on this journey of assembly and discovery! This is going to take a while!
Today I picked up control horns and hardware, 3 x HS-55 servos, and my dealer offered me a choice and I went with Thunderbird 18A ESC from Castle Creations.
I glued the tail together with 30 min epoxy with 1/3 microballoons. I'm thinking to put a couple strips of fiberglass down along the sides of the vert stab. Looks a bit frail... Maybe because I'm not used to foamies!
Tonight we slapped in the HS-55's and reinforced the surrounding seams with epoxy with 1/3 microballoons and a double layer of fiberglass. Almost did not mix up enough glue for this job - be generous its cheap enough!
We also attached the ailerons with hinge tape (needed some sanding to get free movement both ways) and checked the squareness of the tail and rudder.
So far so good! I am doing ok at keeping everything neat and even. :p
Tonight I got the tail's control rods routed and secured.
Note the epoxy and fiberglass used to secure the tubing to the fuselage. Later, this can be coated with a sanding sealer and sanded down nice and smooth. For now, I am just wanting to get her ready to fly!
Thanks to those handy Du-Bro connectors and horns - they make what could have been difficult job a lot easier. I got all the tail control surfaces working, but the tail is a bit stiff and the tail wheel is not up to snuff. I'll come back to these later.
I checked my servo geometry, and it looks good so I put locktite in the screws.
The tail is basically done but I may have to re-work the tail wheel. These foamies don't give you much material to work with and I had to reinforce with some sheet lexan and fiberglass, and bit of CF strip was needed to get this far.
Thanks!!! Glad to have a free place to blog about my hobby stuff!!
Got the canopy fixed to the wing today.
First, I coated the area around the top of the wing with epoxy heavy with microballoons. Then I laid down a sheet of fiberglass to reinforce the area under the canopy. I let that dry. Then I expoxied the canopy down, and let that dry. Then I reinforced the seam all around the canopy with epoxy heavy with microballoons and a stip of fiberglass. She is solid and firm! I put in balsa crossbars in the canopy so it can be grabbed as a sturdy handle for the whole plane.
And, finally I found a place to put the AR6000 receiver. I had to Dremel out a little space for it and sunk it down into the main balsa deck. The receiver has a nice 'lip' around the edge and it stays there nicely. A bit of hot glue tacks it down solidly.
Also, I figured out the motor mount. Very simple, strong, and light. I am pretty sure the Thrust Line is going straight through the plane. The angle looks good.
A bit CF rod is hot glued on either end to hold down the wires away from the servo arms.
I like the way it came out! Nice and neat. The control arms are clear of the servo wires and receiver. The wood spacers help keep the LiPo pack centered and secured, and are notched to accept rubberbands.
Hey Crash! Good to hear from ya! No date for the maiden yet. Yep this old plane was in production prior to the internet, I think. There is very little information about it out there.
And I've never seen a push-pull elevator/aileron setup like this. Seems unique to me. Can anyone else show me a similar setup?
I played with the radio setup again. The V-Tail mix does not do the correct job for this control surface setup.
What did work is pretty odd. I set the radio for default on Wing Type. This means no Flaperons, no V-tail, no Elevons, no nothing.
Then I just setup two custom mixes. I mixed Channel 3 (right servo) about 100% into Channel 2 (left servo) and then I mixed Channel 2 about -100% into Channel 3. VERY WEIRD, but it works!! I say "about 100%" because this needs tweaking to make sure both the left and right sides have even travel.
The manual calls for about +/- 1" travel on all control surfaces. I set up my Dual Rates in Newbie Mode for about half that, with 30% EXP for smoother crusing.
Yes, its within my skill to build this plane, but beyond my skill to fly her anywhere close to her full envelope. Maybe after a couple years of practice... This plane will be capable of crazy advanced aerobatics that are way beyond me. For now, the plan is to get her in the air and stable.
By unanimous decision, we decided to glass the whole wing.
That's why you go heavy with microballoons in the epoxy mix - this stuff sands down nicely with 120 grit sandpaper. Use a dust mask. Have a shop vac handy.
The whole wing can be glassed in sections. When the fiberglass sheet is placed over a smooth surface that is smoothly coated with EPMB (Epoxy Plus Micro Balloons henceforth), it won't come down perfectly. You have to coax it into perfect form with a gloved hand.
After you've done your best to get the sheet down nice and even, a wet finger can press down the parts that are too thick, even out the edges, etc.
Ideally, the glass should be tight as a drum when the epoxy cures.
Don't worry if its messy, or bulky or uneven in parts. It will all sand down nicely to any smooth surface you want.
After the wing is fully glassed, I will tediously sand and sand until the whole wing is nice and smooth and form-fitting.
Then I will coat it with Sanding Sealer (Minwax) and sand down one more time - perhaps even to 400 grit. Then she'll be ready for paint.
I am adding some weight but remember this plane kit was designed before there were LiPo packs. I tested the motor with the GWS 8060 prop and it pulls hard! This plane, even with the extra weight, should be capable of vertical climbing. We'll see!
The wing is sanded down and is nice and smooth all over. This stuff sands down really well, and makes a lot of dust! Have a shop vac handy!
It sands down so smooth, you can't tell where the seams between the separate sheets of fiberglass are. Nice! All the bits that appeared too bulky are sanded down as smooth as I like them. I left it thicker around the wing roots and around the canopy. Best bang for the buck - stress points are stronger, weight is minimized. The whole wing feels light and strong.
Time for another dry fitting!
Note the small intake cowling added to the nose. This will get a hole underneath and will provide cooling, mainly for the the ESC. An outlet cowling will be added at the tail end later. I expect good air flow through the whole fuselage.
Those small cowlings are really simple. Take an appropriately shaped bit of some kind of blister-pack packaging. Its polycarbonate plastic - "Lexan" - very tough and light.
Cut out the bit you need (I took mine from a package that contained those little flourescent light bulbs) and tape it in place. Then just glass over the whole thing as we have been doing. I think two layers is just slightly overkill, but I like the strength.
Overall weight should not be a problem - the wing and canopy together are 5 oz. The plane still feels very light. Eagerly building toward the final weigh-in... :p
I went over the wing and canopy with Sanding Sealer (Minwax), and sanded with 220 grit. WOW! Nice and smooth as glass, but not perfectly even, as can be seen in the pics.
I am thinking another coat of sanding sealer, or maybe Minwax PolyClear to fill in the low spots, leaving a perfect surface for Krylon H20 Arctic White to go on. Yes it will add a little weight...
The main thing today was that I decided to dump the stock Ailerons. Look at 'em! So flimsy... I manufactured my own out of balsa, and used Du-Bro hinges.
Excellent, dude! These are the finest hand-made control surfaces in my zip code at the moment, for sure!!
Notes: Control Horn mounting - I drilled holes and flooded the area with thin CA - the balsa soaked it up and the whole area around the Horn is really solid - like hard plastic. Before it cured, I used gel CA to fix the Horn down. Solid as a rock!
For the hinges, I used 90-second epoxy. Fast and strong. Don't get any actually in the hinge itself! Time enough to get the position just right without taking forever.
We have now glassed the entire left side of the fuselage.
Also, we designed a lightweight and incredibly strong landing gear mounting.
Two strips of CF and 10 times around each leg with fiberglass - this thing can hold 100 times the weight of the plane before shearing off. If the landing gear get munched, the whole thing can be Dremel'ed away and replaced without too much pain.
The mess will be glassed over and sanded - it will look smooth and 'part of the plane' when painted over.
Also, we sanded around the cooling air intake cowling and opened it up for air flow.
We have a piece of polycarbonate plastic (Lexan) from a package that contained a cake decorator (squeezer bag thing) that will make a perfect Cooling Air Exit Cowling for the aft end. It can go in after the epoxy has cured.
I also stuck on a nose cone thingy and am continuing to experiment with the GWS 8060 (8x6) prop. Looking good so far...
When the tape came off, I was disappointed to see a lot of paint had leaked around the edges of the tape. I am touching it up now. Also, the finish was not a good as when the paint was wet. Good enough, but nothing stellar. Overall the wing/canopy looks pretty good and is pretty much done. Pics of that later.
The buttplug that sold me the kit did not include a cowling to cover the motor. So, I have to craft one.
I started with a Parkzone P-51 cowling for $2.50. I cut it up to fit the nose of the Stuntman.
I then taped it on with regular clear tape, making sure it had a good fit and position.
I then glassed it. After it cures, I can remove it and add more fiberglass. It should sand down nice and smooth. Later, I will glass in a 'chin implant' to smooth out the bottom line.