HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Apr 27, 2012, 11:43 PM
Registered User
EdSoars's Avatar
Salida, Colorado
Joined Sep 2002
873 Posts
Discussion
ArtHobby Alpha 1.5m

I just ordered an ArtHobby 1.5m Agena S electric sailplane today, and an hour later Andre called to suggest two new designs just in, the Alpha EV 1.5m, and the Gamma EV 1.2m. I described the kind of rough and tumble conditions we have here in the Rockies, and he pointed out that the one-piece FG fuse has a much stronger V- tail mount than the CF tailbooms have. It uses the long-proven wing from the Hyper glider, with the HN1033a airfoil. In my 8-10 years' experience with 3 AH ships using this airfoil, from 60" Hyper to 98" Thermic/Castor, it has a great speed range.

After the box arrives, I'll start a build thread for the Alpha EV 1.5m.

Power will be AXI 2212-20 motor with Jeti 18 amp ESC-BEC, ArtHobby 30mm spinner, and 8-4.5 Graupner prop.
EdSoars is offline Find More Posts by EdSoars
Reply With Quote
Sign up now
to remove ads between posts
Old Apr 28, 2012, 02:20 PM
Chess club geek with wings
blunight's Avatar
United States, FL, Cape Coral
Joined Aug 2008
1,063 Posts
subscribed!
blunight is offline Find More Posts by blunight
Reply With Quote
Old Apr 28, 2012, 11:15 PM
Registered User
EdSoars's Avatar
Salida, Colorado
Joined Sep 2002
873 Posts
I usually do some small mods on AH kits. A friend has a CF sock over his Falco fuselage...says it's very tough. I may try it with a very light CF sock from Soller Composites, and make the ailerons a little bigger, but it will be fairly stock, or what's the point of a review?

I also cover the wings with film, not paint. I don't need hang time as much as penetration and ding resistance.

I look forward to everyone's suggestions.
EdSoars is offline Find More Posts by EdSoars
Reply With Quote
Old Apr 29, 2012, 01:40 AM
Theoretical Modeler..
plane_tech's Avatar
Joined Oct 2007
2,159 Posts
Been flying a Sky-EV 1.7 for about 2 months now and love it. I wish I would have used film instead of the paint as recommended now. The paint is not even close distinguishable at altitude. Other than that, I love the plane. Good luck. I will be looking forward to watching someone else's build thread on one of these. Mine is here
plane_tech is online now Find More Posts by plane_tech
Reply With Quote
Old Apr 29, 2012, 08:21 AM
Registered User
EdSoars's Avatar
Salida, Colorado
Joined Sep 2002
873 Posts
Nice thread and photos, plane-tech. So there's a Dunedin in Fla? I think of it as being in Scotland and New Zealand. Continental drift no doubt.
EdSoars is offline Find More Posts by EdSoars
Reply With Quote
Old Apr 29, 2012, 08:53 AM
Registered User
EdSoars's Avatar
Salida, Colorado
Joined Sep 2002
873 Posts
Here is a sketch of the modifications planned for the Alpha 1.5 EV, shown in RED

Including:

Slightly enlarged ailerons: I like lots of roll response with a little less aileron deflection, and plenty of spoileron effect on landing and bailouts from way-high thermals.

Tension hinges on ruddervators: nothing wrong with ArtHobby's hinges, but the tension hinges are frictionless, slop-free, and easy to replace.

I may try a balloon to install a CF-KV sock in the front of the fuselage...depends on how stiff the fuse feels out of the box.
EdSoars is offline Find More Posts by EdSoars
Reply With Quote
Old Apr 30, 2012, 09:47 AM
Chess club geek with wings
blunight's Avatar
United States, FL, Cape Coral
Joined Aug 2008
1,063 Posts
re: your proposed hinges-
Are they the type created with Blenderm where the tape is stuck to itself with about 1/16th of overlap and placed in a "X" on either side of the control surfaces?
blunight is offline Find More Posts by blunight
Reply With Quote
Old Apr 30, 2012, 10:06 AM
Registered User
EdSoars's Avatar
Salida, Colorado
Joined Sep 2002
873 Posts
I make them from a 2" strip of packing tape (clear film type). Put it down on a hard, clean surface, sticking it down only on the very ends, then cut it lengthwise into two 1 strips. Pull one strip up, put a 1-2" piece of tape on either end, sticky sides together, then lay it down on the hard surface, sticky side up. Pull up the other 1" strip and lay it down carefully on the sticky-side up strip, with 1/8" to 14" overlap, or about the same thickness as the control surface LE. Mark off 3/4" pieces along the overlapped center, then cut them apart.

You should have several 3/4 wide hinges, 1/4" long, sticky sides reversed.

Applying them takes some practice, but they're superior hinges. They do need a spanwise strip to keep the control surface from moving away from the main section, which would introduce slop in the movement.
EdSoars is offline Find More Posts by EdSoars
Reply With Quote
Old May 03, 2012, 04:13 PM
Registered User
EdSoars's Avatar
Salida, Colorado
Joined Sep 2002
873 Posts
The Brown Box has landed.
The packaging is as usual well done with bubble wrap on all sides.
The contents were in perfect condition, and included all the needed parts except
for the motor mount. This is probably because of the wide range of motors that customers may wish to use.

The workmanship of the wings, tail and fuselage is flawless. The canopy is CF, not the CF "look" of some imports.Not a big deal, but nice.

The wing mount T-nuts are already installed, and are for metric bolts. While this may save some building time, I have always swapped out the the metric nuts and nylon bolts for imperial sizes. I also prefer the front bolt to be larger than the rear bolt, which allows the wing to break the smaller bolt and pivot in a rough landing.

It will be interesting to see the recommended procedure for drilling the wing bolt holes to fit the installed nuts.

The AXI 2212-20 motor I want to use is a very tight fit. This will be interesting, too!

There is just room in the fuse for a 3-cell 1550 mah battery, either on edge or flat.

I couldn't resist ordering one of ArtHobby's beautiful ow-drag spinners. These are pricey, but the machining is impressive. If you are carefully matching prop pitch and diameter to your motor, be aware that these spinners reduce the nominal prop diameter by almost an inch, since the blade pivot is inside the spinner cone, instead of outside, as on standard spinners.

Now I'm going off to find some loose time to work on this little beauty...
EdSoars is offline Find More Posts by EdSoars
Reply With Quote
Old May 05, 2012, 04:01 PM
Registered User
EdSoars's Avatar
Salida, Colorado
Joined Sep 2002
873 Posts
Getting into the build:

I will only post variations from the standard building instructions, and a few cases where I use a method that might make things go easier for ArtHobby kit builders.

The biggest change will be the fuselage: it is very light, and will not survive many landings in the rough ground here. If you fly over grass, you won't need to do anything to the fuselage. Here, we have rough ground, rocks and brush, and one hit will snap that beautiful, curvy shape.

I've ordered a supply of braided carbon fiber sleeve from Soller Composites, which will form a smooth-fitting "sock over the whole fuselage. I'll lose the nice white gel coat, but at least I'll get to fly the Alpha more than once!

BTW, Soller also has braided sleeves in 100% carbon, 50% carbon-50% fiberglass (colored too!), and 50% - 50% carbon-kevlar. The carbon is easy to apply. Carbon- kevlar is hugely strong, but very difficult to finish. More on this later in the build.

Rudder control: the directions show elevator-only, but I like to have a rudder function to mix to the ailerons for landing control. Two servos under the wing saddle get pretty crowded, with minimal room for servo arms. I've glued two servos onto a strip of lite-ply. This will be screwed down to the fuselage floor for flight. The elevator housed wires will be glued to a thin carbon fiber tube, and the elevator ends will be removeable, so the whole assembly can be slipped forward to exit through the hatch.

Wing center join: the directions show how to carve and insert the wing joiner blocks, which are quite effective. But I like to have a very hard wing center joint, so I sanded out a depression in the foam before inserting the joiner blocks, and filled it with thickened 30-minute epoxy.

This is one of the places I wish ArtHobby would spend some work to improve: The blocks are tedious to carve, especially if you want a smooth fit. It is CRITICAL for the blocks to fit so that you don't tip up one leading edge relative to the other. This will give one wing more incidence, which will require offsetting aileron trim, which is no good at all.

Next change: I am going to cover the surfaces with TowerKote, so it would be difficult to cover the elevators hinged as they are to the vee tail. I also like the easy repair-ability of tension hinges. So the installed hinges (which are perfectly functional for those who are going to paint the tail) were cut apart and the joints sanded to a sharp edge.

Lastly, for now: Another thing I wish ArtHobby would improve: no motor mount is included, not even material for making one. This is a time-consuming piece to shape and install. I traced the motor mount shape and drilled the center and four screw holes. Then I glued the mount to an old 35mm film can, to give me a reference true round outline to sand to. I then sanded the mount down until it just fit inside the nose, from the front. Then I cut if off the film can, sanded it clean, mounted the motor, and tested the fit.

I had to extend the hatch cutout about 3/16" forward to allow the motor wires to come back over the motor can without touching it. When I glue a mount to the fuselage, I don't use epoxy. Epoxy is brittle, so I use a glue like Shoe Goop, Marine Goop, or E6000, which are all flexible and make a strong joint.
EdSoars is offline Find More Posts by EdSoars
Last edited by EdSoars; May 07, 2012 at 11:39 AM.
Reply With Quote
Old May 13, 2012, 06:36 PM
Registered User
EdSoars's Avatar
Salida, Colorado
Joined Sep 2002
873 Posts
Progress:

Carbon socking the fuselage. This is a surprisingly easy, quick, inexpensive method to make a fairly weak fuselage very strong. The captions tell it all.

Wings are covered. Nothing different here other than the enlarged ailerons. I had a bad roll of TowerKote...no adhesive, very weak. Pretty disappointing. My preference in color is to make the top white, the bottom black, dark blue or dark red, with strongly contrasting wing tips.
EdSoars is offline Find More Posts by EdSoars
Reply With Quote
Old May 13, 2012, 06:47 PM
Registered User
EdSoars's Avatar
Salida, Colorado
Joined Sep 2002
873 Posts
Socking the fuse part 2: again, the captions tell the story.

The original fuselage could be compressed in your fingers. I would guess that the fuselage would break before the wing bolts, which is not good. The socked fuselage can't be deformed in your hand. Something else, hopefully wing bolts, will break first.

Since I'm not interested in slow duration flying, I didn't bother weighing it before and after socking. My bad. I'll weigh the fuselage later, if anyone's interested.
EdSoars is offline Find More Posts by EdSoars
Reply With Quote
Old May 15, 2012, 10:50 AM
Registered User
EdSoars's Avatar
Salida, Colorado
Joined Sep 2002
873 Posts
Bench maiden! Taped together the parts and...
It's an Airplane!

looks like it should fly.
EdSoars is offline Find More Posts by EdSoars
Reply With Quote
Old May 17, 2012, 10:20 PM
Registered User
EdSoars's Avatar
Salida, Colorado
Joined Sep 2002
873 Posts
Got all the parts stuffed into the fuse, balanced out at 22oz, = 10 oz/sq ft. Perfect for fast, agile, soaring flight.

The carbon socked fuselage needs the 1500mah 4.2oz 3S battery moved up to 1/2" behind the rear of the motor. The 4.9 oz 1550 oz battery is right back against the servos, which means it's about 3/4 further back than the 1500mah battery.

The receiver, a 5-channel Hitec single conversion 72 mhz, is behind the servos. Photos coming.
EdSoars is offline Find More Posts by EdSoars
Reply With Quote
Old Jun 14, 2012, 10:26 AM
Registered User
EdSoars's Avatar
Salida, Colorado
Joined Sep 2002
873 Posts
The Alpha has been flown enough now for me to make an informed statement of its performance:
OH WOW! With the structural mods, and a 1550mah battery, it flies at 10oz/sq ft, heavier than
advertised, but oh my, the high speed passes and huge pullouts!

I flew yesterday at a local hang glider launch at 9500', which didn't hurt the speed runs any, and flew two transmitter batteries out. There are plenty of places where there is considerable shear, and the Alpha just punches through without a twitch. The landings were into scrub oak, and with the CF wrap on the fuse, and 5 mil mylar over the LE's of wing and tail, there was never a scratch.

This is one of the sweetest-handling little planes I've ever flown. There are only two small changes I'd make in future builds: make the ailerons full span for slower landings, and increase the ruddervator area for better rudder control. Elevator was sufficient, and with full span ailerons acting as snap flaps, the aerobatic envelope would be much bigger.

In the two-plus hours the Alpha belted around the sky, there was never an instant of the feeling of total control and responsiveness. Congratulations ArtHobby and Andre!

Yes, I know videos would be appreciated, but the choice between shooting and flying is only going to come out one way. Besides, it appears this thread has gotten submerged somehow.
EdSoars is offline Find More Posts by EdSoars
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Build Log ArtHobby Sky-EV 1.7M Build plane_tech Electric Sailplanes 222 Oct 14, 2013 12:36 PM
Discussion 2m powered sailplane vs 1.5m DLG Windy Miller Hand Launch 34 Aug 21, 2012 08:21 PM
Wanted Still Looking to Buy or trade for 1 - 1.5m DLG cdninoh Aircraft - Sailplanes (FS/W) 0 Mar 28, 2012 04:15 PM
For Sale Arthobby Sky 1.7 EV Arf Rockitglider Aircraft - Electric - Airplanes (FS/W) 1 Nov 20, 2011 09:10 PM
For Sale Arthobby Sky 1.7 EV Arf Rockitglider Aircraft - Sailplanes (FS/W) 2 Nov 16, 2011 08:39 AM