|Wing Area:||~290 sq. in.|
|Weight:||as built: 12.125 oz.; as specified: 10.5-11 oz.|
|Wing Loading:||as built: 6.02 oz/sq. ft.; as specified: 5.25 oz/sq. ft.|
|Servos:||Hitec HS-55 (3)|
|Transmitter:||Hitec Eclipse 7|
|Battery:||3S1P 880 Polyquest Lipo|
|Motor:||Himax 2015-4100, geared 6.6:1, 11x4.7 APC prop.|
|ESC:||Castle Creations Phoenix 10|
|Available From:||Wing Warrior|
The kids are back in school, the days are getting shorter, the leaves are changing colors,. It can only mean one thing - indoor flying season is just around the corner! So, when the Straight Edge EPP from Wing Warrior came up for review, I jumped at the chance.
The Straight Edge is a very aerobatic 3D flier with a full flying stabilizer instead of separate stab and elevators for the ultimate in tail authority! While a bit large for indoor, it has proved itself as docile enough for golf dome flying, and is happiest in a hover or high-alpha slow speed maneuvers, which work out just fine in a small area.
The Straight Edge EPP comes as a very complete kit. Everything but the motor, electronics, and glue are included. Even a set of quality decals are provided to finish the plane. Furthermore, there aren't too many parts to work with. So, it's a fast build.
The kit comes with a CD that contains a catalog and the instructions for all of Wing Warrior's products. As it turns out, this information is also available on Wing Warrior's website. Even printing to CD instead of paper, information always seems to be out of date before it makes it off the press! I would suggest downloading the instructions on the web if possible to make sure you have the latest and greatest version. I found some differences and decided to use the website instructions.
The instructions are complete, and the build isn't difficult, so I won't rehash all the steps here. However, I do want provide some additional hints or tips and I provided build time for groups of steps.
Author's note: The Straight Edge employs a fully articulating horizontal stabilizer. In other words, there is no horizontal stab with elevators attached. Instead, the entire horizontal stab moves. That said, in this article I generally refer to it as an elevator since "flying stab" or "articulated horizontal stabilizer" is just too awkward.
I put some water on the 3/8x3/8 wood motor mount stick which is the motor mount stick before applying the polyurethane glue (brand names: Probond or Gorilla Glue) to help activate the glue.
I am glad I checked the holes in the plastic pivot plates used for the elevator. In my kit, the holes in the plastic pivot plates were just a hair too small for the rod. I reamed them out with one or two rotations of my hobby knife.
I taped off the wing so that the 3M glue would not get on other parts of the wing.
To attach the ailerons, I decided to use clear duct tape. It is flexible and has a very aggressive adhesive. Additionally, to get the necessary gap between the aileron and trailing edge I found that a piece of trailing edge stock balsa made a good tool. Or, since the elevator rod was very close to 2mm wide. I could've used this as a spacer as well.
I used poly glue for the wing spar. I cut the slit, test fit the spar, removed the spar, then put a bead of poly glue on top of the slit then pushed the spar into the slit - dragging the glue with it.
Very straight forward step. The pre-applied double-stick tape was a nice touch that made the kit all that much easier to put together.
This page of steps was straight forward, but, some helpful hints might be worthwhile. First of all, I needed to make sure to center the servo horns before gluing the servos into place. Also, I suggest attaching the EZ Links to the servo horns before attaching them to the servos. And, I suggest wrapping the servos in tape so that you can remove them more easily later if need be. Finally, when installing the tail servos, I found I had to cut off the flanges that would normally be used to screw down the servo. I did this to get the servo seated as deep as instructed. Goop was used to glue in the servos.
The elevator attaches to the elevator spar by sliding the spart into a flute on a piece of coroplast that is glued to the underside of the elevator. When attaching this coroplast, you should line up one of the coroplast pieces as per the instructions - by lining up the forward edge of the coroplast with the line. But, for the second piece of coroplast, you should line it up so that it's center flute is in line with the other piece's center flute. This will keep the elevators' front edges in line.
The instructions say to glue the receiver in place at this point. I skipped this step at this point since I wanted to wait until I established the balance point before committing to the receiver location.
I found clamping and taping the wing in the saddle was sufficient to get the wing square. So once I had everything secured, I eyeballed it and adjusted it as necessary. I used poly glue for this step. I also applied some poly glue to secure the entry cut into the fuselage.
A couple things to note when attaching the elevators. When the control rods are attached to the elevator, check the movement. When I was at the final trimming stage, I found that the elevator hit it's control rod when in an extreme down position. So, I had to bend the rod a bit and even add a z-bend near the servo horn to keep it clear.
The instructions say you do not necessarily need to glue the elevators to the spar. I strongly urge you to glue them. Originally, I didn't, and I'm pretty sure this was the prime contributor to a problematic maiden flight (see below). That said, were I to build another, I would not glue the elevators to the spar until I completed the model and done all the bench-top trimming and adjustments, since it might be helpful to be able to remove the elevators if any adjustments (such as bending the elevator control rod) were necessary. But, once I had everything trimmed out on the work bench, I wish I had chosen to glue the elevators to the spar/rod.
One interesting phenomenon of the fully articulating horizontal stab is that if the control throws are large enough, the elevator can actually "flip over" when the servo goes back to neutral. At full deflection the elevator is in such a position that as the servo goes back to neutral, the elevator can keep going around (and not back to the "straigh and level" position) and thus the elevator ends up in a throoughly un-neutral position. As it turns out with the fully movable horizontal stab, a little control throw goes a long way. So, it is important to turn down those endpoint adjustments and do a few full-deflection tests on the bench before becoming airborne.
Since the final steps of securing the radio equipment and checking the control surfaces varies so much from builder to builder, I didn't bother to time this step. But this step did include applying the decals. These decals finished the plane nicely and are helpful to maintain orientation. Although the edges of the wing decals have come loose sometimes, they did stick right back down. It might've helped to hit the adhesive side of the wing decals with some 3M77. However, I haven't tried this, so I would want to test the 3M77 on a scrap piece of decal first.
As far as setting up the aileron trim, be sure to trim them so they were in in-line with the chord of the wing. Originally, I had a bit of camber trimmed in and this resulted in a twitchy plane that pitched up quite a bit. Once I adjusted the ailerons so they were neutral, the plane handled much better.
As far as control throws are concerned, I used the recommended throws for 3D flying for the ailerons and rudder: 45 degrees for each. However for the elevator, I found that 30 degrees was sufficient. That said, I suggest using only 15-20 degrees for the elevator for the maiden flight.
So, there's about 2.5 hours of building time (not including waiting for glue to dry). And for me, the finishing steps probably took about an hour - maybe an hour and a half. But, this also included some soldering work I needed to do to get the electronics ready. So, it's definitely a quick-to-the-sky kit!
My final AUW was 12.125 oz. This is over an ounce heavier than the specified weight range of 10.5-11 oz. However, I'm not too surprised by this. For one, I'm using Polyquest 880 packs which are about 0.5oz heavier than the recommended TP packs. And, I've probably got more wire on the plane than I need. I could probably save a quarter of an ounce by trimming some of the servo connections. Fortunately, Motocalc predicts about 20oz of thrust. So, I was pretty sure there wouldn't be any thrust:weight problems. :)
Motocalc also predicts 9 amps at 10 volts for this motor/GB/prop I'm using. Using my trusty Whattmeter, I measured 9.2 amps at 9.7 volts. Given that the Polyquest batteries I used are rated for 12C, the current draw was fine. Regardless, the pull I felt during this testing was promising.
Well the maiden flight was only about 5 seconds. I ran up the throttle, gave the plane a gentle toss and as it started to climb it suddenly nosed in from about 10 feet. Unfortunately, the impact was accompanied with some flying foam and plastic. The plastic was the prop breaking. The foam was the little nose piece that sits under the motor. Additionally, the motor mount along with a good bit of the foam to which it was attached broke off.
After picking up the plane and inspecting the damage, I noticed the elevators were no longer neutral but rather were in a down-elevator state. I believe the cause of the crash was that the elevator was affected by the propwash. As I fed in up elevator, I believe the propwash pushed the (unglued) elevators back to a level position and I'm sure at some point in the short maiden I probably started bringing the elevator back to neutral which was now down elevator. This would have resulted in the fast dive to terra firma.
Of course this won't happen to you since you followed my instructions above to glue the elevator to the spar!
Anyway, back at the shop, I took out the poly glue, and glued the nose pieces back in AND glued the elevator to the spar. It was as good as new.
With the repairs completed and the plane ready to go, I took the plane out again. That moving horizontal stab along with a generally tail-heavy setup (as per the instructions) made for a very responsive plane in pitch. So, be ready for it! I was not used to that much elevator authority and so it took some low rates (20%), some expo (-80%) and some time to get used to it.
One of the aspects of the plane that attracted me to it was that it actually has an airfoil and isn't just a flat wing plane. Granted, it's a symmetrical airfoil (which I guess a flat wing is the ultimate example of), but it still has a more natural feel to it in the air. It's rather difficult to explain, but when I've flown flat wing planes, they always felt strange to me.
That said, it is not a sport plane. It is a 3D plane set up for high-alpha maneuvers. So, when asked to fly "normally", it flies rather tail heavy. But, again that horizontal stab easily compensates for this. And nonetheless, it can be flown through the usual aerobatic maneuvers like loops, rolls, cuban 8s, etc.
Furthermore, even in this tail heavy configuration it doesn't really stall. If you look at the video, you'll see a landing where it just plops down like a leaf. Some folks have reported on RCGroups.com Discussion Forums that adding some weight to the nose makes it more of a sport flyer. But, where's the fun in that? Seriously, though, once you get used to the standard set-up of the plane, you can work it through sport maneuvers quite easily.
The plane is clearly meant to be a 3D plane. I am a novice 3D flyer. I've horsed around a little with this type of flying, but one of the reasons I was eager to get the Straight Edge in my hanger was to practice and expand my 3D flying. After flying the plane myself and having a couple of other more experienced 3D flyers try it out, it appears this plane will live up to my expectations and then some.
The plane is very easy to hover and torque roll. It takes a few seconds to start the roll, but a touch of aileron accelerates this lag. Furthermore waterfalls and tight loops are very easy (and fun). Similarly, parachutes are fun as the plane kicks right up into a hover at the bottom of the dive - again thanks to that big ol' elevator.
Knife edge flight is pretty easy with this plane. The large rudder and tall fuselage provide plenty of surface area to fly knife edge. I can't say I noticed a strong tendency to pull towards the canopy or away from the canopy. If it's happening, it must be pretty small.
The plane is also just fun to throw around the air! For example, pushing both sticks up and out, or up and in makes from some fun tumbles from which the plane recovers with hardly any help and without losing any altitude.
I get about 13 minutes of flight time on the 880 Polyquest pack. This isn't just drifting around, either. This is with lots of hovering and tumbling and other maneuvers where the prop is pretty heavily loaded. The packs come down warm. The motor is barely warm.
The following video shows a couple of early flights with the plane. So, the flying is pretty docile but still shows the plane is easy to launch and fly basic 3D maneuvers.
At the beginning of the article, I mentioned indoor flying with this plane. Well, it's a rather large plane for indoor, but it is so docile (once you tame that horizontal stab) that I found it was just fine in the golf dome I fly at.
The one problem I had with the kit is that the depron control surfaces didn't give much material for the control horns to grab onto. Also, the depron is rather flexible. This led to control inputs that would not translate to crisp maneuvers, since the control surfaces would move back to near neutral positions in the prop wash. So, I added some thin balsa strips to the control surfaces to provide rigidity and to provide a place for the control horns to attach to.
Overall, I must say I'm really enjoying this plane. It flies very easily and it's ruggedness and ease of repair (poly glue and EPP are your friends) makes it a very good 3D plane for the novice and experienced pilot alike. I look forward to honing my 3D skills with this puppy.
Thanks to fellow E-Zone Member Sal C for helping out with videotaping and flying.
Long Beach Municipal, California, United States
Joined Feb 2003
I had an original straight edge that was EPS foam, which came in at under 10oz with the stock GWS 300C motor, GWS 100 esc, 3 pico servos and a GWS 4RH receiver, azarr antenna and 2 cell etec 1200. Great plane loved every minute with it until the wings broke. This version had no spar.
Chris did a great job redesigning with EPP and adding the carbon wing spar. My EPP version plane came in a little over 10 ounces and flies even better then before. Its fun to push the envelope knowing that a crash will rarely result in any significant damage. With this low budget power system I easily get 10 - 12 minutes of fun 3D flying.
In my fleet the Straight Edge is one of my all time favorites and makes my local little grass park a perfect early morning diversion.
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