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Old May 06, 2008, 08:53 PM
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Build Log
DANCER Series: 39" to 62" Wings, 6 fuselages: Powered, Slope, & Night Flying

LAST UPDATED ON 10-24-2011

The DANCER wing/ aircraft series designs continue to be the most efficient gliding KFm variant wings that I've flown to date.

The DANCER II design (featured later in this discussion thread) uses a mid-mounted pusher prop and a thicker EPP fuselage, and can fly with either an under-cambered polyhedral 'trainer' wing, or with the 46" span KF3P aileron glider wing. Dancer V (started on page 10) has the 'Sport Fuselage' designed for mounting removable landing gear with wheels or skis.

In August and September of 2010, I began work on another generation "DANCER III" , Designing a new generation of larger test prototype wings, and a new sleek EPP foam fuselage with a folding propeller and a larger E-Max CF2812 motor. I also began development of the MH32/KF3P airfoiled wing series, which use shallower depth KF variant stepped discontinuities.

Design concepts, Build information, and lots of build sequence photos for the DANCER III design start on page 2, post 26 of this thread. It flies 58" and 62" span MH32/KF3P wings. Later in the development process, both of these larger wings were modified to use two aileron servos so that flaperon functions could be used to shorten the landing approach glide path.

DANCER IV is a lighter weight scaled-down size sleek EPP fuselage design similar to the DANCER III, flying a 24 gram motor and a folding prop on a 2S LiPo pack; it's flying with a 46" span KF3P wing.

Links to web pages for the pusher-powered versions (The original 'Slim Beagle' and 'Dancer I') which were designed in early 2007 are shown in a photo below are also included in this discussion thread.

VIKING
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Old May 06, 2008, 09:16 PM
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MAY 6th, 2008: The HLG Fuselage

While this wing has been flying since May of 2007 on the E-powered pusher DANCER fuselage, I finally had time to complete the Hand Launch Glider fuselage. The photos below show the results.

With a wing loading of about 3.5 ounces, this glider will handle lightly in thermal conditions, yet is clean enough to penetrate the winds on the slopes nicely.

The HLG fuselage is a pod & boom style- simple & quick to build, and very durable.

The forward fuselage is made from a 16-1/2" long section of 1.3# density EPP which tapers from 1-1/16" wide just behind the nose, to 1/2" wide at the wing's trailing edge. The Pod's maximum depth is 2".

A pair of HXT500 5 gram servos are used for the rudder & elevator. A Berg 4L receiver is also installed in mine.

I'd discovered something neat about the Plasti-Kote paint... it actually bonds fairly well directly to clean nylon filament tape! This allowed me to add the color & visibility to the fuselage pod very quickly and easily. (Touch-ups will be equally quick & easy later when desired, too!)

The wing construction for the three DANCER series wings, as well as the tailgroup construction options, are on this web page:

http://www.stenulson.net/rcflight/slimbeag.htm

More before long!!

VIKING
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Old May 06, 2008, 09:22 PM
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There's a video of the E-powered DANCER available, filmed from launch to hand-catch.... it is a high-resolution large image video that is 56MB long- not dial-up friendly...

It was a windy day, and, as often is the case, I was flying alone... so I set up the camera on the tripod and tried to fly as well as I might within the 'window' that the camera was covering. This is unedited footage, & will give you some idea of how these wings can perform in windy conditions. There's some gliding flight included too- but it was a windy day, as you can hear on the video.

So if you'd like a preview of this wing in action, here's the link:

http://www.stenulson.net/rcflight/dancer1.mpg

VIKING
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Old May 06, 2008, 09:37 PM
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I've really enjoyed watching your transition from Gene Bond's great Blu Beagle to the Dancer. I love your E-powered Dancer and am looking forward to building one. I may just going ahead and build this one too when I do. My problem is that I have several planes that I want to build right now, but no time at the moment. The list is beginning to stack up. I have a couple of slopes around here and have only flown my Weasel and Unicorn wing on them. I would love to see how different it would be to fly this as a sloper also. It looks great! I'm sure TLAR would work fine on the fuse, but it would be nice to have a pdf or drawing of it. Congratulations!
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Old May 06, 2008, 10:24 PM
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Daddy-O

Thanks for the kind words!

Combat slope ships use the nylon filament tape covered EPP fuselages, and withstand horrific hits without a problem (most of the time...??) This aproach works out well for the DANCER HLG for flying here in the Central Colorado Rockies, where many of our slope flying landing zones are nothing but rocks- no exageration!

Next step in this build log is the test flights, verifying the CG (between 38% & 40% of chord) and verifying the slight positive wing incidence. Fine-tuning these details make a MAJOR difference in how cleanly these wings can glide- or not.... This is where TLAR just doesn't get it....

Most of this will initially be done on the slopes. Once that's done, I may also play with ballasting up this same fuselage for heavier winds- we see a LOT of that up here! (That'll be a simple approach- cut a slit through the tape & foam centered on the finalized ideal CG, and slip in a couple of sheets of lead, & tape it closed. EPP & K.I.S.S. go together SO well!!)

I'll possibly also tape a launching hook onto the belly for use with a light bungi launcher for flat-country thermal hunting launching ... [a shoulder separation that's haunted me for a couple of years keeps me from being as effective at hand launching to altitude as I'd like to be...]

Plans will get drawn up with the results of the flight testing reflected. The 3mm Depron tail feathers on the E-powered DANCER have performed very well, so using that material is also a good option. Foamie builders always seem to like to use the materials & techniques they have... and that's great! I'll try to show how I put together these designs to end up with the glide efficiency and wind handling capability that I have experienced.

More soon!

VIKING
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Old May 06, 2008, 10:30 PM
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Bruce, you have another beauty! Congratulations, she looks like a winner. Ya gotta love those KFm3 foils.

Tony
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Old May 06, 2008, 10:42 PM
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Tony,

Thanks for the kind words, & the inspirations early on that were a part of motivating my delving into this entire research & design project. It's taken far too long to put this one in the air, but it's poised for action now!

Yes, the KFm3 variant airfoil that I designed on this wing last spring , at 9% thickness, has seemed in the past to be able to float the slowest in minimum sink trim, without going into a 'mush', yet handles high winds and higher speed flying equally well.

I'll also be able to fly the other two (KFm2, 7-1/2% thick) wings on this same HLG fuselage, and get further direct comparison information.

The FUN continues!!

VIKING
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Old May 06, 2008, 10:50 PM
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I hear you Bruce. I've pretty much standardized most of my newer designs on a KFm3, 8-10%, depending on chord. I found my 60" Blu-Baby AP2, with it's KFm3 (9%) wing had a better glide than my 72" Saiplane with a Selig 3021 airfoil. Also, as you observed, it handles wind well and is embarrassingly kind in it's stall characteristics. I can fly the plane with full back elevator with a stall breaking.

Tony
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Old May 07, 2008, 10:17 AM
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The value of optimizing balance & wing incidence

I find that, for thermal gliding perofrmance especially, it's important to fine-tune both the balance / CG, and the wing incidence (relative to the horizontal stabilizer.) For HLG gliding efficiency, having the wing incidence set at 1-1/4 to 1-1/2 degrees positive works very well for most HLG designs. [This is measured to the chord line of the wing = center of leading edge to center of trailing edge.]

As an example, I recently had installed a ~ 1/8" soft balsa leading edge shim on the Slim Beagle fuselage to fly an undercambered wing on it; that wing works better when set at a more positive incidence angle. I later went to one of the local slopes, and mounted the #1 DANCER design wing (7.5% thick KFm2 type, step at 50%) for some slope flying. Just to confirm what I'd observed previously, I left in the shim temporarily.

The affect was quite noticable... the glider was a bit 'mushy', and would not penetrate as cleanly as I knew it could. So I landed and quickly removed the shim, the tossed the aircraft back into the ~15 MPH winds.

What a difference! Now, the plane would penetrate and move out, handling far more cleanly and smoothly. the soft balsa shim had been slightly crushed, so the difference on a 7" chord wing with that shim in place was only 3/32" higher.... but when talking about glide efficiency and clean wind penetration, just that modest amount 'off' is really quite noticable!

I've seen the same affects in thermal gliding efficiency. Modest shifts on CG location can also have significant influences of glide performance efficiency. So if you're looking to get the best glide performance in light lift conditions, it definitely pays to make the fine-tuning adjustments, and observe how they affect the flight performance of your setup.

Fine-tuning the balance, so that the aircraft flies with the elevator in-line with the horizontal stabilizer, also contributes to best glide efficiency. On the 9% thick DANCER KFm3 variant wing, (with the primary top step at 50% of chord, and the secondary thinner top step at 70% of chord, with the RG-15 forward airfoil contour), the balance has worked very well in the past at 40% of chord.

These two adjustments are inter-active, so getting both optimized is worth the effort in my mind.

DANCER HLG Test flights- later today? It's possible if the weather cooperates- scattered snow showers are forecast! I'll report soon!

VIKING
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Old May 07, 2008, 10:31 AM
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Bruce, we've noticed the same incidence issues in the Blu-Baby. Originally designed with a 4-40 UC airfoil at a +2 degree incidence, we've discovered that the KFm2 and KFm3 perform significantly better with 0 degrees incidence. Some have also fine tuned it with a 1/16" shim and reported good results.

The incidence produces a dramatic difference. I'm looking forward to reading about your test flights. Good luck!

Tony
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Old May 08, 2008, 08:12 AM
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It was later in the day when I got out to try to do some flying yesterday, with a storm system moving in with gusty winds- not a good day to catch thermals on the small hill I was launching form. Winds were off-angle, sometimes running lengthwise along the hill, so there really wasn't much of a slope lift component. But I tossed it into the viriable air quite a few times anyway.

With the flat-built wing, I have found in the past that it's useful to use both ailerons and rudder for better control; it's also nifty in light thermal lift to be able to turn / circle with gentle rudder input, while being able to use oposite ailerons to keep the wings from banking too steeply.

Polyhedral HLGs can be very responsive to rudder only, and are easier for beginners to fly in that respect for hand launch thermal hunting. The DANCER HLG, with it's full-house control, is very versitile, and has handled slope winds to above 20 MPH with good penetration and authority in the past.

At one point as the storm was building & the gusts were getting stronger and more changable, I added a couple of ounces of ballast lead (1/16" thick lead sheet sandwiched between the wing and the top of the fuselage) to increase wing loading and wind penetration. This technique shows promise, and I was definitely able to penetrate the gusty air with more authority; but the wind direction was staying parallel to the face of the small hill, so there was no real lift being generated.

I finally gave up on the day & put the HLG back in the car, having caught only one small rough patch of warm air that I rode for a couple of minutes... I was an hour or two late that day getting out for real thermal generating conditions, so I'll be looking for another day to really fly the Dancer HLG in decent air conditions.

I'll also see about getting out in slope lift conditions before long, & play further with the ballasting.

VIKING
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Old May 08, 2008, 08:42 AM
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Congrats on your successful maiden, too bad about the weather. That's a great trick regarding the lead sheet. Where did you get lead sheet?

Tony
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Old May 08, 2008, 09:07 AM
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A friend found it for me in a scrap metal yard many years ago; the sheet lead was used as shielding in an X-ray room, built into the walls, floor, & ceiling. There were left-over ends of rolls. It's 24" wide, very close to 1/16" thick, and pure soft lead- very easily cut or shaped.

(It's also prized for casting balls and bullets for muzzle loader rifles because of it's being un-alloyed & therefore not hardened, so it disappears from scrap metal yards, too.) My supply is dwindling from what I once had, but I still have my own supply.

A small piece about 1/2" square went into the nose of the DANCER HLG for final balancing; I simple made a slit on the top of the nose through the tape, slit a slot in the foam just large enough for the flat piece, & slid it right in.

Someone has to supply sheet lead to the builders who do these jobs, so it should be possible to track down a source.

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Old May 08, 2008, 01:45 PM
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Do you have the plans for this nice model?
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Old May 09, 2008, 07:50 AM
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The wing build instructions for the DANCER series of wings can be found on this page:

http://www.stenulson.net/rcflight/slimbeag.htm

Since the previous version of this web page was getting a bit bulky, with a lot of images, I've split up the information; there's now a new DANCER page that starts with the Dancer Powered Fuselage, and goes on into the Dancer HLG fuselage version. The first two wing builds are still on the Slim Beagle page linked above, while the 9% thick KFm3 wing build is on this newer DANCER page:

http://www.stenulson.net/rcflight/dancer.htm

Construction of other fuselages is also shown in more detail on the Slim Beagle web page.

I have not drawn plans for the HLG fuselage yet, although it is a fairly simple approach. I used a piece of EPP foam 16.5" long, 2" high, and 1-1/16" wide, contoured and tapered into a smooth pleasing shape. You can shape your own as you desire; the photos show what worked for me, as far as shaping and component placement.

The tail boom is a CF tube, 4mm / .157" in diameter, ~24" long; it extends back 14" behind the rear end of the EPP foam pod, and when extended 10" forward through the foam, it provides a stiffening 'backbone' forward to the front of the servos.

The main detail to build carefully on the EPP pod is how the CF tailboom is inset into the top surface, to end up with the desired wing incidence. The bottom of the wing at the leading edge needs to be ~4mm above the CF tail boom tube, and the wing's bottom trailing edge needs to be just touching the tail boom; so you need to carefully cut a slot into the top of the EPP foam block to allow the CF tube to be inset in this way.

The horizontal stabilizer and elevator are 11" wide. the elevator has a 3" width / chord. The horizontal stabilizer has a chord of 3" at the root, and 1.5" at the tips, with the corners rounded.

The vertical stabilizer is 6" tall; the rudder hinge line is angled back from vertical about 1-1/8" at the top. The vertical stabilizer is 6" long where it mounts along the top of the horizontal stabilizer and onto the tailboom. (refer to the photos in previous posts for clarification.)

The rudder's maximum chord is 2-3/4", contoured to the rounder shape shown in the photo to clear the elevator's upwards deflection. I simply decided at the time I was building these tail feathers to shape the rounded contour on this rudder the way I did; you can exercise your own 'artistic license'. The primary factor is to have roughly this much surface area with the control surface hinge lines at about 14-1/2" back from the wing's trailing edge (14" behing the rear end of the EPP pod fuselage); that will give you suitable stabilization and control authority for the DANCER wing.

For the 7.5% thick KFm2 type single step wing, I find that it glides best when the balance is set at 38% of chord. For the 9% thick KFm3 Dancer wing, I like the glide efficiency with the balance set at 40% of chord. The 7.5% thick wing can be a slightly faster, cleaner gliding wing for slope soaring service in higher speed winds.

Optimum glide efficiency does depend on your doing the extensive shaping of the wing's airfoil - carving, sanding, and heat forming- to achieve the desired airfoil contour. Leaving a blunter leading edge and trailing edges will reduce glide efficiency and increase drag. Refer to the drawing of the 9% thick airfoil on the web page for an idea of what you might want to end up with after doing the final airfoil shaping.

[Tech Note: it's said that 50% of the lift that a wing can generate is generated by the effective shaping of the front 25% of the airfoil.... food for thought!)

I hope this helps for those who may want to build a DANCER HLG right away; after I complete more test flying, I may draw further plans on graph paper. The wing incidence and length of tail moment are the important details; the rest can involve a bit of your own 'artistic license' in ending up with a pleasing shape working with the materials you have available.

VIKING
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