|Aug 14, 2012, 10:12 AM|
Skyangel-J/Power Screamer 50mm EDF
Every so often, a design comes out that reminds you of something else. Then upon closer look, things are completely different. This was the case with the new Screamer. The first time I saw this model, there were many fond memories of my good old Parkzone Stryker. I cut my teeth on prop jets with that model. It would float or zing depending on how much power was applied.
Then the pain set in. It wasn't called the Stryker for nothing. That prop hanging on the back would strike my fingers in the blink of an eye if attention to the hand launch wasn't 100%. It was at this point I remembered why I retired it, it was to prevent any further loss of blood. That was a well loved plane, but it was time for self preservation. The old Stryker was boxed up and relegated to a dark, hidden corner of the hanger. Every time the mood struck me, I would start to pull out that box and bring the old friend out for some fun and the pain set in all over again. I will not allow another prop strike to mangle my fingers so the old friend got pushed back into that dark corner with great sadness.
The next glance at the Screamer reminded me of a few other models that had an EDF pod sitting above the fuse, but for whatever reason those never appealed to me . Perhaps it was the not so streamlined look, maybe it was still the fondness for the stryker, I don't know. The Screamer gives a very different feeling. Upon closer inspection, this looks better with every glance. No prop induced carnage, no ugly EDF pod sitting above the fuse, even the wing servos are well protected by the servo arms protruding through the top of the wing with the control horns residing on top of the elevons. The body has a neat, sculpted look as it blends into the wings, a clear canopy, this thing looks hot! I just couldn't resist this one and made the purchase.
I made the purchase from a relative newcomer to the hobby industry, http://www.hobbyb.com out of Canada. The website shows an extensive listing of the Skyangel line, more so in fact that any other vender I have run across. The pricing is quite reasonable and seems to cater to both ends of the consumer wish lists.... those that want plug and play along with those that want airframe kits to use their own electronics. I had not ordered from them before, but had run across a few others that had and could recommend them, so I dove in and indulged myself.
The model arrived well packaged and free from damage, the assembly couldn't be more simple. In fact, the parts mocked together in 15 seconds as the only assembly of the airframe that was required was to add the nose, rudders and clear canopy. I had chosen to purchase the airframe only. I already had a stash of 9g Towerpro servos, the stock 4300 kV motor and fan from other Skyangel / Jpower jets so there was no need for me to purchase a plug and play model.
I was quite impressed with the quality of the foam. The fit and finish are top notch with no "gatorskin", bubbles or pits in the surface. The parts interlock effortlessly and the EDF housing has a few high stregth magnets to hold the cover in place, a system that has worked with other Skyangel models so it should work just fine here as well. With a 20" wingspan and low weight, the low wing loading of this model should allow it to either float or haul nicely. No possible prop strikes, sexy looks and the forgiving construction of EPO foam makes this a winner in my book. Now that the basics are out of the way, it's time to fully assemble this beastie.
For those wanting virtually immediate flight time, the plug and play model just needs your own receiver and lipo for almost immediate fun
For the kit build, there are several items needed. EPO foam can be glued with a mulititude of different products. Epoxy, contact cements such as UHU Creative, polyurethane glue, even CA. Normal eps foam requires a foam safe glue as something like CA will melt the foam. EPO has a different chemistry and CA does not destroy the foam. Each type of adhesive has it's benefits and it's faults. Normally I would tend to use a 5 minute epoxy, but what I've noticed is that adhesive tends to turn yellow with age and sunlight exposure. Since this model will retian some of it's white color scheme, I will use a normal CA for any exposed glue line such as the rudders and the nose. A more flexible canopy glue like UHU creative will be used to glue the clear canopy to the battery hatch.
Next, two 7-9g servos will be required for the elevons mounted on the underside of the wings. depending on what manufacturer servos are used, there may be a need for harness extensions. The servo leads need to be approximately 12 inches long in order to reach the area where your receiver will be located. A simple 4 channel receiver is all that is needed. Since there are only two servos and a speed control, nothing fancy is required. If your transmitter is a basic model with no programming features, you would need a V-tail mixer as well in order to active the required elevon mixing of the servos. I will be using a Spektrum 6100 receiver, only because I happen to have one sitting in my parts bin. Any 4-6 channel receiver will work just fine. In the kit version, there are no control horns or rods included so this build will show how to fabricate these yourself.
Now for the power system. The manufacturer has designed the model for their 50mm EDF unit and their 4300 kV outrunner with extension.
The motor has been proven in other models to be perfectly happy on 4s voltage. The manufacturer supplies this motor and fan in their packaged planes and are run on a very conservative 3s 850 mAh lipo. Turning up the power to 4s voltage has shown a decent increase in thrust and speed with no adverse affects to the motor. The EDF unit, that might be another story. There appears to be a slight variation of quality when it comes to the stock EDF housing and rotors. Some aren't concentric right out of the box, while others are perfect. This issue will be addressed a little further in to the build, tips will be given on how to ensure a reliable and light weight fan unit.
Part of the power system is an appropriate speed control. this is another item with varied quality control. The speed controller as supplied in the other Skyangel jets is rated for 20A. On 3s voltage there is still headroom. on 4s voltage we are flirting with the upper end of it's rating. There are reports of great results on 4s voltages while there are other reports of the speed controller going up in a puff of smoke. This author has experienced great results with a stock 20A, however..... my intent with this build is to make sure there is little chance of failure. I've chosen a 30A esc, also available from hobbyb.com so that the option of installing a higher powered motor and fan would only involve swapping just the fan and motor. Even if the stock motor and fan is used, wide open throttle for the entire duration would not cause an overheating speed controller. the a 30A continuous rating and 40A burst rating, I'm confident there will be zero issues with only a miniscule weight difference. http://www.hobbyb.com/aeolian-evolut...th=126_129_140
The last factor in the power system is the flight battery. The battery bay is decently sized and could hold a wide range of lipos. To keep weight to a minimum, I will be using a 4s 800 mAh 40C lipo as long as the correct CG can be attained with that size of a battery pack. Now on to the build...........
The servos are centered and their arms installed facing upwards though the top of the wing. This is a nice design as the arms won't catch on anything during a belly flop landing. The servo leads are pressed into the channels cut into the wing and follow along to the cutout that resides under the place that the EDF unit will mount. There is a center channel for the servo leads and the speed control that runs up to the cockpit area where the receiver and lipo will be installed.
The speed controller chosen was an Aeolian 30A (40A burst) that is rated for 3-4S voltage. This was from www.hobbyb.com as well. The speed controller is programmable, and comes with programming instructions. Hooray! Anyone who has purchased any kind of budget controller that didn't come with instructions will relate to the joy here. Everything was soldered up to the motor and fan and tested.
Once the powersystem was tested, the assembly was installed in the fuselage. The EDF unit was glued into place with UHU creativ ( or UHU POR) to prevent any movement while in use. The fan cover is magnetic and just pops into place. That by itself doesn't seem strong enough to hold the fan in place, so that's where I chose to glue the fan with a flexible glue. The glue is strong enough to hold everything in place, but with enough force, the fan can be removed with no damage.
So with the servos, receiver and power system installed, it has been set aside for the glue to dry. Since control horns and control rods are not included in the bare kit, I need to supply my own. I've taken a short cut and instead of fabricating the control horns, I dug out a set of drjohnslaser.com ply control horns. They are laser cut and come in sheet form, you just punch out a set and glue them into place. I've used them on many occations and are actually stronger than the plastic ones supplied in kits.
The control horns are now glued into place and control rods with Z bends are added.
I just happen to get the idea to try this. I seem to remember this design from somewhere, for the life of me I can't seem to remember where. It won't be finished this way, I just wanted to fab it up this way for pics.
The vertical stabs were then glued in the proper V configuration, the nose cone was glued as well and we're ready to rock and roll!
A 3s 1000 mAh 30C lipo was used for the first test hop to see what the performance would be like as the manufacturer intended. The CG was checked for the recommended 45mm back from the intake lip. There was a break in the rainy Florida weather so we went out for the maiden flight. The excitement and anticipation never gets old when you toss an unproven model into the sky. There was just a hint of air movement, the throttle was opened up and I gave it a toss.......
Oh my. I felt like I almost botched the launch, the model quickly took off out of my hand and started to climb, evidently this one doesn't really need an upward arc on the hand launch. It even surprised my wife who was operating the camera, it took here a few moments to find the model in the sky. That is a rare occurance as she's quite good and tracking an RC plane. In a few seconds she was on it again. The power is superb, the rate of climb is stunning, it quickly became evident this was going to be a HUGE winner. On the flip side, the power off glide was among the best I've seen on an EDF jet. I was blasting vertical, shutting off and doing dead stick glide tests. The plane tracks well, I noticed that I had forgotten to completely clear out all the transmitter settings. There was some differential programmed in to the elevon mixing so a little remixing needed to be done.
Here is the intial test hop, a better video will follow after the transmitter has been reprogrammed.
So in summary, on 3s this model has essentially unlimited vertical. The glide range is so exceptional that you'll need to plan your landings. When I mean plan them, I mean you can cut throttle down wind, make a gradual turn and you will still likely overshoot your landing spot. By far, this is the best performing 50mm jet that Jpower has offered to date. It's evidently very effecient because this is using the same motor and fan as every other Jpower model yet the performance leaves the others in the dust. I can't stress enough how fantastic this little hod rod performs.
The Plus side:
*Quality molded EPO construction.
*Great fit of the parts.
*Outrageous performance on stock power system.
*Clear canopy included.
*Plenty of room for electronics and lipo.
*Quick build time.
*Well packed from vender.
The Minus side:
*Lack of control rods, horns or instructions in airframe kit.
even though the assembly is easy, those items should be included.
*No pilot figure like what is included in the plug and play version.
I was able to put a few more flights on the Screamer for testing. The first test was with a 3s 1000 mAh for slow speed handling tests. This this will actually high alpha and almost refuses to drop a wing. I did slow speed moves that I wouldn't dare try with any of the other JPower jets. This acts like it has functional canards in a stall. It just floats nose high, and is easy to keep in line. I can't find a single bad trait. For me, that's a almost a miracle.... If there is something wrong, leave it to me to uncover it.
The next tests were 3s vs 4s in back to back tests. The Aeolian 30A esc showed no signs of any problems and performance is...... Oh my. All I could do was hammer the throttle, start this childish laughter and watch while it rolls like a drill straight up and doesn't slow down. Seriously, it specs out in a few seconds. What a jewel this turned out to be.
Here is the 4s test hop clips.
This jet steps right smack into the serious performance catagory and this author gives it the highest rating of the Jpower 50mm jet line. I can't quite say it's for a beginning pilot, but I cannot imagine anyone with some previous skill not thinking this is complete blast to fly. Even without instructions, the build is pretty simple and anyone with prior assembly experince can figure it out with zero drama. Get one and you won't be sorry.
|Aug 14, 2012, 02:45 PM|
|Aug 14, 2012, 04:20 PM|
Even though I retired my Stryker, it has occured to me that if someone really wanted something ballistic, it wouldn't take much to intall a 500-600 Watt pusher prop setup in the tail of this. Can you imagine that much power in a 20" wingspan with low weight to boot?
|Aug 14, 2012, 06:33 PM|
Joined Jun 2010
I get the feeling that the 580mm wing span would be hard to follow if you got this aircraft going to fast. I think they need to scale it up to either side of 800mm. Nice looking little model, but just a little on the small side for my taste.
|Aug 14, 2012, 07:39 PM|
santa barbara, CA
Joined May 2009
hey joe, fwiw , we launch all the pusher wings dead stick then powerup. hard to get bit that way and its easier than u may think, again, lots of wing area and low loading.
wind up and give them a heave. fun jets , strikers , and wildwings.
but it's cool w/ no prop and we belly them in on the tarmac strip so no prop damage w/ the edf.
|Aug 14, 2012, 07:56 PM|
|Aug 14, 2012, 08:32 PM|
I tried the palm down forehand stroke but was not very successful with it.
I have settled on the backhand palm up frisbee toss as shown in this video
My success rate has been 100% with a 7x5 prop.
|Aug 14, 2012, 08:52 PM|
|Aug 14, 2012, 09:04 PM|
Joe, this thing is a blast! I have a Himax in mine and I would love to see what it could do with few hundered more watts. I'll be watching.
|Aug 15, 2012, 11:10 AM|
Updatred the original post with more info..... these 11 hour work days are killing me, I have such little time to build.
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