Thread: Mini-Review Bird of Time ... ARF
View Single Post
Old Sep 03, 2012, 12:47 AM
R2R is offline
R2R
Find More Posts by R2R
R2R
Registered User
R2R's Avatar
United States, FL, St Johns
Joined Nov 2009
674 Posts
Mini-Review
Bird of Time ... ARF

Model
Name: Bird of Time ARF
Mfg: Great Planes-Dynaflite
Span: 118"
Controls: Rudder, Elevator
All Up Weight: 67.5 ounces
Price: $169.99 online
Battery: 1500mah 5-cell nimh
Receiver: Airtronics RX700 (fhss-1, 2.4 GHz)
Elevator servo: Hitec hs-65HB
Rudder servo: Hitec hs-325HB
Transmitter: Airtronics SD-10G
Hi-Start used: 100 feet of NSP Pinnacle Standard Hi-Start Tubing and 250 feet of mono-filament. This rubber is intended for 2M-3M gliders.

Pilot/Reviewer
Skill: Novice-Intermediate. The weekend warrior who is slightly past beginner level, but not yet flying contests.
Although I've been flying RC Gliders since 1986, it was only on and off, and I just barely learned to thermal before putting it aside completely in 1998. I picked it up again in 2010, and have been hooked ever since. This year, I feel like I've finally graduated beyond the weekly cycle of fly - crash - fix - fly, and can usually find a thermal or two. And just so you know, I was not paid by Great Planes, and I bought this model and equipment with my own funds. The statements here are purely my opinion and done for the fun of it and in the hope that it helps anyone considering the purchase of this model.

Background
I wanted to have an open-class RE or RES sailplane for hi-start and winch launching. Even though I had an RES model on the building board, the build was taking me longer than expected because of my lack of available building time, and I didn't see my time freeing up for a while. I was also committed to keeping the budget low to save for some other higher priority toys. It looked like the BOT ARF fit the bill: open-class span and performance, with generous wing area and an airfoil that was designed to be more slippery with plenty of Phillips entry.

Flight Report
At the field around 8 AM the wind was dead calm, humidity around 90%, the temperature was at the dew point, and a thick fog was everywhere hovering around 20ft AGL. We decided to wait it out thinking that the rising sun would soon burn off the fog, so my buddy and I just shot the breeze while drinking coffee. By 9 AM the fog hadn't budged. I decided to assemble the Bird of Time ARF and throw some hand tosses to make sure it was okay for launch. After another half an hour, a slight breeze finally started to blow the fog away. After it cleared the area, which was the east end of a Navy OLF runway, you could see the back wall of the fog marching west down the blacktop.

Our winch was not available, so we had planned on flying electrics, and I also brought my NSP Pinnacle Standard hi-start for my pure gliders. I laid out the hi-start and hooked up the Bird while my buddy flew his Bixler. The first launch went well, just a nice easy glide back to landing to make sure all was well with the controls and balance. I was using a fair amount of hi-start tension, pulling back an additional 2x the length of rubber, about 200 feet of stretch. I could just barely hang on to the plane before release, and the BOT wings looked solid without any fluttering or flexing that was noticeable.

On the next flight, I got 3:04 minutes as I found some weak pockets of sustained altitude. Launch 3 was a good one, and I immediately steered downwind to where Don had specked out his Bixler. When I got there, I had only about 100 feet of altitude, the lower section of the thermal already gone, and I had to turn immediately around to get back to the LZ.

Then, after playing around for a bit with my ST Models ASW-28 electric, I launched the BOT a fourth time. It came off the tow as usual without much excitement, just a nice and easy fly-off at roughly 200 feet. I explored to the right without finding much. After turning 180 degrees to tack across the field, about midway across, the BOT just starts rising -- Eureka! I let it cruise a little more past the peak of lift, and start turning, just shallow easy turns because I didn't have much altitude. And every time I crossed that spot, I could see the BOT rise. At this point, I remembered to start my timer. After a few revolutions to center the thermal, I was up and away, and a vulture had joined me. The vultur e and i just kept climbing, very slowly. I took it up to almost speck, and the vulture bugged out. I kept going with it till I was fully specked out, and the stab disappeared. The thermal was very slow rising, not a hat sucker. Just a fat warm bubble is how it felt. It must have taken a full 3-4 minutes just to get up there. So I decided it's time to get out, and started cruising around. I must have caught another five thermals, the lowest one at around treetop height, and specked it out another couple of times. My neck started to hurt, and when Don asked me how long I'd been up, I looked down at my transmitter timer, which was at 24 minutes. The BOT caught another thermal while Don took a break and we chatted about books and movies. I think my thermal turns were smoother when I wasn't concentrating so hard. The BOT drifted down in sink, and half-heartedly trying, I couldn't care less and wasn't able to catch another riser, so I brought it around to final. When the BOT landed, the timer read 36:15 -- my longest flight ever.

Cons
  • Fuselage is not rigid in compression in the boom area. When you put your fist around it and squeeze, it easily gives. The gel coat may crack easily because of this. The tailboom is stiff in the vertical and horizontal directions however. So I don't believe that elevator response is hurt in any way by the "squeezable" fuselage boom. I did not mod it in any way to try and stiffen, and it seems fine in flight. It looks like some internal stiffeners have been installed along the lower centerline and maybe the top centerline at the factory. The wing saddle area and cockpit area are reinforced with plywood try and provide lots of rigidity there.
  • Weight is higher than it should be in my opinion. The nose is pre-ballasted, and I had to add another 1.5 oz lead in the nose, even while using a standard-size servo in the nose for the rudder.
  • Tail-mounted elevator servo -- adds tail weight and you are forced to use a micro servo for the elevator. The manual says that the counterbalanced elevator design eliminates the need for lots of servo torque, however.
  • It has a tendency to tip stall if you try to turn too tightly, even with lots of airspeed.

Pros
  • The BOT was ready to fly in about 5 hours of build and radio install time.
  • Very good L/D with flat, graceful, majestic gliding, both in straight flight and in shallow-banked turns. I was under pine tree top height around 2 football fields away and made it back to the LZ, taking a straight-at-me heading.
  • Signals lift very well, either with wingtip jostles or the rising of the entire airframe.
  • Seems able to climb in the lightest of lift.
  • Good penetration for an older design. At high altitude, to escape a thermal, I gave the plane a smidge of down elevator, and it moved out of the area very well and steadily.
  • Very responsive to rudder inputs. I'll probably program some dual rates on the rudder.
  • Great customer service. My fuselage had two 3/8-inch size chips missing on the gel coat where the fiberglass weave was exposed. I reported it to Great Planes, and they sent a new, perfect fuselage to me the same week.

Overall
The BOT ARF is a great value for someone wanting minimal building and open class L/D. You will have no problems launching from a 3M-rated hi-start, but I have yet to launch it on a winch and can't say how it will perform there. This glider is a model for an intermediate pilot, and possibly a beginner with expert supervision and/or buddy box: evident in its bolt-on wing design, lightweight wing construction, and precise control input requirements while flying. It's not a model you can get away with over-controlling, but it does provide a terrific glide and control responsiveness. A great performing sport glider, and with a few modifications, maybe an entry-level contest glider.
R2R is offline Find More Posts by R2R
Reply With Quote