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Wednesday, August 29, 2012

Hobby King Deamon-2000 – Build and Flight Review

INTRO                                                                                       

“Demon” (spelling corrected) describes the personality of this high performance glider perfectly.

Canopy
SPECS
- Wingspan: 79”
- Length: 42”
- Flying Weight: 28 oz (RTF minus battery)
- Wing Cube Loading: 4.5

FEATURES 
- Fiberglass fuselage
- Balsa and plywood wings and V tail
- Push rods with casings installed
- Hardware

REQUIRES
- Motor: 2845 1800 kV
- ESC: 40A
- Prop: 10x6, folding
- Spinner: 30mm with folding blade hub
- Servos: 9-15g metal gear

PAID
- 2855 2100 KV Brushless Inrunner Motor: $13
- 4x Digital Metal Gear Servos: $28
- 50A ESC w/3A Switching UBEC: $11
- 30mm Aluminum Spinner, hub & 10x6 blades: $12
- Model: $120.86 including USA warehouse shipping
= $185 to front door

UPGRADES
- Upgrades linked in price list, above

ON THE GROUND                                                                   

UNBOXING

box
Openbox

The ARF arrived very well packed and undamaged.

APPEARANCE / FIT N FINISH 

As we’ve come to expect, the wings and V tail were beautifully constructed and covered.  So much better than I could do with a kit build.

The carbon fiber canopy is gorgeous and tough as nails.  It is designed to roll up a bit when uninstalled, then unroll to squeeze the fuselage when installed.   I added two CF braces on the underside so it keeps its shape even when uninstalled.

BUILD QUALITY/SETUP

The V tail halves simply get glued in place, I stripped the covering off the portions of balsa at the glue points.

The wing halves slide over an included carbon rod, then get bolted on at the rear of the wing root.  There are strings embedded in the wing halves to help thread the aileron servo wiring.

This only difficult part of the build was getting the wing halves to slide over the supplied carbon rod, it is a very tight fit.  I had to lightly sand, spray with Teflon, then crank the rod in like a screw.  The second wing was a lot easier to waggle on the rod protruding from the first wing half. 

I can transport an 80” span model without disassembly, but the tight wing rod could present a convenience problem for those without 80”  of cargo room. 

I elected to glue the wing and rod up as a single piece, for strength. 

I decided to make this glider a screamer, so I installed a 900W 2855 2100 EDF brushless inrunner motor and a 50A ESC.  The manual calls for a 2845 1800 KV inrunner and 40A.

Here are the measured static specs of my complete setup, including a 3S 1800 mAh battery (20-30 min flight time):

RTF Weight Amps Watts Static Thrust T:W
Ratio
RPM Pitch Speed
35 oz 49 585 74 oz 2.11 22,000 125 mph

TopBottom

GROUND ISSUES


- The carbon wing rod is a very tight fit.

IN THE AIR                                                                              

BLUF

Shocking speed and power.

TAKEOFF

Rips itself out of your hand at full power and climbs to limits of eyesight (estimated 600-800 feet) in less than 10 seconds.

GENERAL CONTROL

Plenty of throw on high rates for extremely energetic slope soaring, but not with excessive authority.

No dihedral equals neutral stability in the roll axis.  Still, easy to fly precisely due to the large wing.

Powered climbs are so strong and so brief that a large percentage of the overall flight time can be unpowered. 

High speed passes become drag limited at approximately 100 mph.  Sound effects feature a smooth inrunner whistle on top of the more violent tear of a balsa drum.  Awesome.

Glide ratio and hang time appear to be excellent, but more testing is required as the maiden was very windy and turbulent.

BALANCE & AEROBATICS

Loops can be tight (20 feet) or huge (100s of feet) with solid pitch authority giving way to mush when approaching the stall. 

Roll authority is the most limited, even on full rates (set up as 120% aileron up throw, 50% aileron down throw), 360 degree rolls were less than spirited.  Adding some rudder (V tail – much like ailerons) helps snap the roll.

Yaw authority seemed a little mushy, but strong turbulence made it hard to assess.

Landing was a pure vertical drop in today’s 20G30 mph winds.

Oddly, even after my power system upgrades, CG/balance still seemed on the rearward limit of just about perfect.

POWER SYSTEM

OMG thrust and speed are strong. 

Full power uses a lot of battery, but several hundred foot climbs are so brief at 100 mph in the vertical (150 ft/sec) that it doesn’t impact flight time that much:

1. Pedal down
2. Nose up
3. Hold for 5 seconds
4. Chop to idle
5. Glide for a few minutes
6. Repeat
7. Repeat
8. Repeat
9. Repeat
10. Repeat
11. Repeat
12. Repeat
13. Repeat
14. Repeat
15. Repeat (You get the idea…)

Cruising at low throttle settings still results in serious pace and barely sips the battery.  Real time telemetry showed 11.6 volts and holding steady with 50% throttle, about 10 minutes into the flight while zipping the big Demon along with a faint whistle.

A lighter setup might be even more fun as for sailplane/slope soaring purists. 

My setup is on the heavy side for a sailplane:

Gliders - 1 to 5 (Deamon WCL = 4.5, setup for speed)
Trainers - 5 to 8
Aerobatic - 8 to 11
Scale - 11 to 15
Racers - 15 and over

ADVANCED HANDLING CHARACTERISTICS

Full up-spoilerons mixed with 12% down elevator mapped to the Aurora 9’s Left Slider were very effective.  In todays strong winds, the sailplane descended slowly on a straight down down-elevator’s 90 degree glidepath, with the nose level on the horizon all the way through touchdown.  Under complete control.

IN-FLIGHT ISSUES

- Sluggish aileron authority at slow speeds

OVERALL

Runs down EDF jets with little effort and out-climbs 700-size helicopters.

Serious high performance soaring = serious fun. 

GRADES                                                                           

Appearance: A
High vis high contrast color scheme.  Some might take issue with the red checkered underside.  V tail profile looks mean in the air.

Aerodynamics: A-
Slippery and sleek.  No dihedral adds flying time with neutral stability.  Relaxing to fly on low rates.  Struggles in roll.

Power System: A-
Short duration, high-amp bursts followed by plenty of glide time to rest the battery.  Battery lands hot after a few 100 mph passes.

Build Quality/Durability: A 
High level craftsmanship.   As good as any balsa & ply ARF on the market.  Fiberglass beautifully done.  Luv the CF canopy.

Value:  A+
2 meter, no compromise shock jock well under $200--shipped.

Overall Grade: A+
Extreme-performance sailplane/slope soarer.   Or is it a jet?

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