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Old Jun 08, 2005, 02:44 AM
Truss-Loc Monkey
Stevens AeroModel's Avatar
Colorado Springs, CO
Joined Feb 2002
4,381 Posts
Building a SA Mini Hotliner (Speed Stick?)

Hotliner performance for EDP-50XC and Feigao 12mm BL. I know that there have been other variations on this theme but here is my contribution to the mix enjoy and experiment...

Background - Faster is better, but fast shouldn't mean nasty to fly... I needed something with a bit more wing area, lighter loading, better stall performance, for overall better manners for our thin high altitude atmosphere.

Having seen some pretty outrageous speed claims for the little EDP-50XC motor coupled to under cambered and flat plate balsa wings... I thought I'd have to give it a try. I think it is safe to say that even built without a pod you can slick the gear assembly enough to achieve speeds in the mid 30's with a wee bit more streamlining you should be able to approach 40mph which is certainly not out of the question on two LiPo's with a stock EDP-50XC and 3x3 prop anything over that would seem to be a gross exaggeration.

This is but the 3rd airframe and 3rd wing design I have fooled with and am posting info here as a reference for others looking to give it a try. A few weeks back I cut a hand full of wing cores and threw together some parts bags for the local group to give it a shot. It has been awesome watching these guys work with the same materials and innovate / implement their own ideas to make their go fast bird - go faster. The build is simple and there is a great deal of room for innovation - it can be accomplished by most anyone and flown by a reasonably confident novice pilot... Could be another great group activity... sort-of-a R/C pine wood derby.

History: Inspired by the little wind busters by airmover I thought I'd have a go at building one up from scratch.

#1 had a 23" wing with a good deal of sweep arcing back from the root to trailing edge. 65 squares and thereabouts 3.5oz it flew off the board - and spurred further experimenting. I tried it in stick form and podded - the podded ship seemed to gain a good 10mph over the stick.. encouraged by this improvement I figured I'd take the plane to the next level and chop the wing down to try and reduce the drag and increase speed - this succeeded only in making the plane ill-tempered and nasty.

#2 back to the 23" span but now with a straight leading edge and wing design ala-sokol... I introduced some dihedral and twisted some wash at the tips... this little gem has been powered with an EDP-50XC on 2S 450 etecs and a Feigao 36 turn motor on 3S 450 etecs... It moves out fast on the stock EDP 50XC motor perfect for the novice... and It goes like stink with the feigao for more advanced pilots (those who have learned to control the GO JUICE).. it makes these very pleasing shrieking sounds (just like a large hotliner - but on a much smaller scale) as it screams past... This airframe is an absolute pussy cat to fly with very wide flight envelope.

#3 To date all of my attempts have been single aileron craft for parkflyer pylon racing - looking for more roll performance and better manners for sport flying I decided to build this one for the little Feigao 28 turn motor and 2S 450 etec... I changed the thrust line a bit and added a quick change motor mount... essentially it shares the same wing and tail feathers as #2 (now at 68 squares)

Well lets get started.
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Last edited by arenablimp; Jun 08, 2005 at 04:22 AM.
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Old Jun 08, 2005, 02:55 AM
Truss-Loc Monkey
Stevens AeroModel's Avatar
Colorado Springs, CO
Joined Feb 2002
4,381 Posts
Start with a simple parts pack nothing fancy here... some control horns, keepers, a carbon tube, and some laser cut surfaces.

Here's the long and short.

The wing is 23" long with about a 3.75" chord at the root feel free to experiment with your own shapes but I find this one to work very well. Cut from 3/16" medium density balsa.

Tail feathers should be made from C-Grain wood - I prefere 3/32" sanded to a slight foil. The tail feathers can be much smaller then what you are used to - remember minimize drag! Also the long moments and speed of this airframe eliminates the need for oversized tail feathers and control surfaces. If you are following along as a scratch builder - use the TLAR method (that looks about right) and remember that less is more on the elevator!

The fuselage is made from a 17" length of carbon tube. I suggest you use something rather robust if you plan on running a BL motor - as you want zero flex back there. For the last two craft I have used .23" carbon tube (thin wall) on this one I am going against my gut and will be experimenting with some lighter materials to prove or disprove the overbuilt fuselage idea

What else? you'll need some epoxy, ca glue, sanding block/sand paper, some 1/32" wire for push rods and some sort of push rod tube.

Radio Gear - GWS R4PII, 5A ESC, EDP50XC, 3x3 prop, Heatsink, 2xHE490 servos, 2S1P Etec 450 lipo.

BL motor - any CDROM class or Fiegao 12mm and proper battery should do it.
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Old Jun 08, 2005, 03:02 AM
Truss-Loc Monkey
Stevens AeroModel's Avatar
Colorado Springs, CO
Joined Feb 2002
4,381 Posts
Step 1

Remove wing core from balsa sheet... I have etched some sanding guides on the surface, pre cut the servo pockets, pre cut the ailerons, and scored the center for dihedral. Please flip the wing over (etch marks down) and back the ailerons with masking tape so they don't come loose while sanding.

Flip the wing back over and, using a sanding block, taper the wing evenly from the 25% etch line to the trailing edge. I like to leave a 1/32"-1/16" trailing edge. Thinner will be more fragile.
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Old Jun 08, 2005, 03:08 AM
Truss-Loc Monkey
Stevens AeroModel's Avatar
Colorado Springs, CO
Joined Feb 2002
4,381 Posts
Step 2

Now sand round the wing core from the 25% mark to the leading edge. I like to leave my tips a bit thick to keep the weeds and brush from damaging them when I plop in for a landing. I also like to slightly round the leading edge from the underside of the wing.
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Old Jun 08, 2005, 03:12 AM
Truss-Loc Monkey
Stevens AeroModel's Avatar
Colorado Springs, CO
Joined Feb 2002
4,381 Posts
Step 3

Blow all the dust out of the deep etch mark in the wing center (if you are scratch building - lightly score the wing center - don't cut all the way through!). Now block up a tip and gently flatten the wing out until the center etch mark pinches together. Wick thin CA glue into joint - hit with zip kicker (ca accelerator) to set dihedral. Note that the angle is exaggerated here - when the block is removed you should have a total of about .1/8" rise at each tip.
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Old Jun 08, 2005, 03:17 AM
Truss-Loc Monkey
Stevens AeroModel's Avatar
Colorado Springs, CO
Joined Feb 2002
4,381 Posts
Step 4

Remove masking tape backing ailerons and cut free from wing blank. Sand a 45 degree bevel in underside of aileron leading edge to prep for a top mounted tape hinge.
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Old Jun 08, 2005, 03:21 AM
Truss-Loc Monkey
Stevens AeroModel's Avatar
Colorado Springs, CO
Joined Feb 2002
4,381 Posts
Step 5

Sand tail feathers using similar techniques to the wing. I round my leading edges, and taper to a squared off trailing edge. Cut free the elevator and taper for hinging. Set up your vertical stab perpendicular to your horizontal stab and glue.
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Old Jun 08, 2005, 03:30 AM
Truss-Loc Monkey
Stevens AeroModel's Avatar
Colorado Springs, CO
Joined Feb 2002
4,381 Posts
Step 6

You'll want to glue your motor to the carbon fuselage and secure with Kevlar thread. I'd suggest this as a better option - lightly sand the carbon fuselage and epoxy an IPS-8A heat sink to the stick. Make certain you don't introduce any odd angles - the heat sink should run parallel with the stick.

While this is drying lets reach for the trusty Min-Wax water based urethane spray and give your wings a light dusting to seal them. Don't get too heavy handed with the spray - just do 1-2 light coats and lightly sand in between.

Here's a tip! I shoot the tips of the wings pretty heavy - enough to temporarily soften the balsa. With the balsa soft you can gently rub the wing tips into an upward curl and set by air drying (or if you are in a hurry use a heat gun). The curl adds a bit of wash at the tips which will assist with your low speed manners.
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Old Jun 08, 2005, 03:36 AM
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highace1's Avatar
Newcastle NSW
Joined May 2004
438 Posts
This looks nice.....

I think i would like something fast...faster the better

Ace
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Old Jun 08, 2005, 03:41 AM
Truss-Loc Monkey
Stevens AeroModel's Avatar
Colorado Springs, CO
Joined Feb 2002
4,381 Posts
Step 7

Lets set the fuselage to the tail feathers and wing. From the #1 prototype it was all too evident that we could benefit from some right thrust for long vertical up-lines... #2 had the motor offset 90 degrees CCW (from pilots perspective) to the left of the stick... moving the thrust line left has the same effect as right thrust. This proved to be too much offset with my heatsink mount and the plane, with Feigao motor, was in need of a touch of down thrust. Well, I think we can get both. You'll want to mount your carbon fuselage to the tail feathers with the motor mount set at 45deg CCW (from pilots perspective). This will get us both the required right and introduce down thrust.

First set the carbon fuselage to the tail feathers. Next measure back 3" from front of carbon fuselage stick - this is where you'll locate the wing leading edge (this position will vary with different gear setup... but has worked pretty well so far). Tack the wing in place with the tail feathers square to wing. Set with zip kicker. Invert and run CA along joint between wing and fuselage - again set with kicker.

It's starting to look like a plane!
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Old Jun 08, 2005, 03:46 AM
Truss-Loc Monkey
Stevens AeroModel's Avatar
Colorado Springs, CO
Joined Feb 2002
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Step 8

I cut some lengths of 1/4" square balsa to strengthen the fuselage to wing joint. This also ends up forming rails to support our battery. Don't block your servo pockets.. and notice that I left a notch at the trailing edge without sticks (this is where you'll place the receiver).
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Old Jun 08, 2005, 03:47 AM
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highace1's Avatar
Newcastle NSW
Joined May 2004
438 Posts
Sorry forgot to ask

Are you going to be selling this as a kit or as a freebie? Doesnt seem to be you websit.

Ace
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Old Jun 08, 2005, 03:51 AM
Truss-Loc Monkey
Stevens AeroModel's Avatar
Colorado Springs, CO
Joined Feb 2002
4,381 Posts
Step 9

Now we begin installing the electronics.

I'll add a pair of HE490's (These are available from www.stevensaero.com) Cirrus re-brands these, as does FMA PS10's. The 490's are ideal for this application.

I chose to install my servos as illustrated.

Servos are retained with a drop of thin CA wicked under the servo tabs. This will keep them in place just fine and are easy to pop out for other projects later on (just go real light on the ca!).
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Old Jun 08, 2005, 04:11 AM
Truss-Loc Monkey
Stevens AeroModel's Avatar
Colorado Springs, CO
Joined Feb 2002
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Thanks for the comments.

Here's the plan. I'm throwing this one out to the general public. I'll offer a download that details construction on our web site. I also have set this thread up to foster innovation. It's a simple platform that is easily scratch built in one evening.

Presently there are no plans for a kit in the conventional sense... I will be offering a short parts assembly with laser cut wing and tail feather shapes basic hardware etc... real minimalist stuff. This will keep the costs down and perhaps get more folks flying the mini hotliner. At this time plans, and instructions will be downloadable only.

I made available this parts assembly to our local flying group which should provide most of what you need to complete the airframe. Cost $12.00

Wing laser cut from medium grade 3/16" balsa
Tail feathers laser cut from sorted medium 3/32" Balsa (C-Grain if available)
Length of 1/4" balsa stock
Control Rod Wire 1/32"
Control Rod Sleeve 1/32" ID
3 DuBro Micro Control Horns
3 DuBro Micro EZ Links
17" Carbon Tube
24" Kevlar Thread.

I've setup a page on my site for this project I'll be adding to it over the next few days.

http://www.stevensaero.com/cart/cata...hort_Kits.html

Quote:
Originally Posted by highace1
Sorry forgot to ask

Are you going to be selling this as a kit or as a freebie? Doesnt seem to be you websit.

Ace
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Old Jun 08, 2005, 04:19 AM
Truss-Loc Monkey
Stevens AeroModel's Avatar
Colorado Springs, CO
Joined Feb 2002
4,381 Posts
Gotta get some shut-eye - will finish off your radio install tomorrow - uh later today.
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