MANROW'S AIRWOLF BODY KIT
For E-Flite Blade CX

By the second week after I'd bought my Blade CX radio controlled helicopter, I'd learned to fly it passably, and had spent some big bucks on repair parts (blades, rotor), spare batteries, a light kit, and an onboard video camera. Then, I grew more cocky and flew it more recklessly, which incurred a few more expensive repairs (battery box, 4-in-1 controller). Although I'd bought spare cosmetics (canopy and tail section), I didn't install them, figuring that I wasn't done flying recklessly-- it didn't need to look purdy to fly.

The Multi-Rotor Heli forum at rcgroups.com has been a great source of information: That's where I learned about Thanh Tran's excellent Li Glow Light Kit, Stersman's graphite tailbooms (eBay), ST Lab's kewl 5-in-1 eDVR video camera, and Mike Manrow's schweet body kits for the Blade CX. It didn't take long to convince myself that I needed the Airwolf body kit, despite recognizing that it wasn't a practical, "workhorse" modification. In fact, I had some real reservations about injecting the modeling aspect into my involvement in this hobby. If you put a lot of work into the cosmetics of a model, you're probably going to baby it instead of really flying it. But it was a new doo-dad for my latest obsession, so how could I resist? Besides, I was curious...

HEY, IT'S A KIT! Let me just say that if you want your BCX with an Airwolf body and you're not confident about your modeling skills, you'd probably be better off paying extra for the assembled and painted version. Although it's more expensive, it's an unbelievable bargain for the time and labor (I'd certainly charge a heckuvalot more!). If you're good at connecting the dots, like to customize, and want to save a few bucks, the kit's the way to go.

My first thought after unpacking all the little unlabelled parts was, "where's the frickin' assembly guide?" The enclosed flyer directs you to a .pdf at the website, but that only gives some general construction tips (useful though). Luckily, it doesn't take too long to figure out where most of the pieces go. Unfortunately, there isn't a huge set of detailed photos of the assembled model for you to figure it out by example. Also, since the pieces aren't trimmed, it may not be obvious what the piece should look like in final form. I finally figured out that B7 was for the front landing gear...errr... no, howzabout in front of the windshield? I used intuition to figure out how B3-B6 should probably be assembled. Since I deviated from the standard assembly (skids instead of wheels), I didn't have to figure out what C5 is for...(I think!)

One of the most anxiety-inspiring aspects of assembly is figuring out where to trim. Once cut, you can't invoke a "do over" or press a reset button, and if it's your first time, you can only guess how it's all supposed to fit together. Therefore, it's a good idea to trim conservatively, test the fit, and see what needs to be done next. In the case of the fuselage, it's a little ambiguous which half should be the inner hidden edge for gluing. Although there's an obvious border, it's raised a bit above the finished surface, which may lead you to believe that it overlaps the other half, as shown in picture D. In fact, the parts do fit together well that way. However, if you assemble it that way, you'll have a wrinkly seam showing, offset from the midline of the body. That's the kind of issue you'll have to reason out as you trim and test fit parts. A lot of the time, where trim lines aren't obvious, you just have to cut and hope you haven't cut too much. (Obviously, I can't give authoritative instructions, because I'm just wingin' it!)

Order-of-assembly is another issue where you have to use your modeler's common sense. The online instructions do point out that the rear rotor axle needs to be installed before gluing the halves together. In fact, gluing the body halves together is the last thing you should do.

Before that, it's a good idea to test fit the BCX guts to determine where you need to cut holes for the main rotor & servo arms, and the battery access. As you can see from figs A1 & A2, the mounting holes are marked for drilling. I found them to be reasonably accurate, but had to fudge one hole to make the two halves line up. An option for this prospective problem is to do like E-Flite does, with elongated slots and grommets.

Installation of the side tail fins caused a little bit of confusion because the fuselage halves are marked with bumps... but one is further back than the other. I don't know if this is deliberate, but even if it is, I didn't want mine to look like that. I cut symmetrical holes in the fuselage and mounted them from the inside, just like I'd done with the front winglets.

I should mention that to assemble this kit, you'll need to deal with the issue of gluing. The kit is vacuformed with a very tough plastic that trims well without being prone to tearing. All the Sharpie marks that I've drawn can easily be removed with alcohol. However, it's a tough plastic to glue. As recommended, I've used CA glue (Zap-A-Gap "Superglue"), but it doesn't set up and bond very quickly, like it does with other plastics (styrene & some clear packaging materials). In many areas, I had to use Zip Kicker to force it to set. This naturally produces a frosted, crystaline mess. It's not the strongest bond, but seems sufficient to hold the parts together. This does bring up the question of the finish though, which I'll address later. Obviously, I'll have to do something about the front windshield which has an ugly, frosty seam running through it. It would have been nice if a separate single piece windshield had been provided, but I don't think it will be too difficult to make one.

I decided to use the stock skids instead of wheels simply because they seemed more practical and functional: The skids are connected to the airframe, where all the weight is. Recognizing that hard drops are a fact of flying, I didn't want that weight-inertia transferred to the mounting rods, through the body, through the winglets, and to the wheels. The only way I'd mount wheels is if there were a solid & sturdy support extending from the battery box/frame and through the winglets. What can I say? I wasn't a fan of the show so fidelity isn't an issue, but I think the killer whale-like curves of the copter look very neat.

The incidental benefit of using the skids with this model (versus E-Flite's body) was that I could just do a single bottom opening for the skids and battery access. Because the Airwolf body is wider than the stock BCX body, there's no reason to drill separate holes for the skids; therefore, body removal is actually easier than the stock body... if you do like I did.

Body removal was a big deal for me. I knew that if I built it as intended, I'd probably be too lazy to switch it out-- you have to remove the main blades to fit the guts through the bottom access hole. So, I could either turn this into a dedicated shelf queen and buy a second BCX, or destroy all my hard work when I eventually did something foolish and reckless at flytime. Therefore, I decided to follow E-Flite's example and turn it into a two-piecer.

The front canopy is fairly light, so it's mounted with velcro instead of the rods. Ideally, it should break away instead of splintering on frontal impacts, but doesn't provide any protection for the bare-nekkid 4-in-1 board-- I may have to do something about that, or rethink the mounting method. But it does make body removal quick and easy, and gives quick in-the-field access to the swash plate and the trimpots on the 4-in-1. The main downside of the two-piece fuselage is aesthetic-- the seam doesn't look very attractive, and this will be more obvious once it's painted.

I did some flight tests in this unpainted state, and it performed well. Without the front canopy, it was extremely nimble and stable, with more pep than the stock BCX (not surprisingly). With the front canopy attached and the battery in standard position, the forward/reverse trim needed to be adjusted full back, and handling was a bit more challenging.It's clear that the controller and battery were working hard to keep this fatty up in the air. The weight will increase slightly once I paint it and add a light kit, which will slightly shorten flight time. As long as it still flies, I can accept the that. I don't expect great performance from this, since the purpose of this mod is to make a purdy copter. For lightweight performance (and onboard video), my BCX wears Stersman's graphite tailboom, and for general bashing and night-flying, it wears the Li Glow-equipped E-Flite ensemble.

 

PAINTING FOR THE IMPATIENT With the clear body, the seams and crazed CA glue looked terrible, and I wondered if I'd really blown it. There was a noticible problem with the fit at the tip of the nose, where both halves had a bit of wrinking from the vacuforming process-- this kept them from a close fit. Since the seams looked so bad, I was distracted and didn't work very hard to force a better fit at the nose, which in retrospect, was a mistake.

It was impossible to tell how all this would really look until it was painted. I wasn't striving for perfection: The fact that this would be a flying model meant that I wasn't going to use any putty to fix seams, because that adds weight. Besides, putty is rigid and tends to snap off if the part is flexed.

To paint this kind of plastic you use a special kind of paint formulated for Polycarbonate/Lexan, which is available at hobby shops in the RC car section. Normally, RC car shells are painted from the inside so that they'll appear super shiny on the outside. This also protects the paint from scuffing. In this case, because of the glue seams, I painted it on the outside and dulled the shine with a mist of Testor's Dullcote. The paint sticks really well and tolerates flexing.

I did this quickie paint job because I'm horribly impatient and needed to satisfy my curiosity. As you can see, the seam doesn't look bad at all, being comparable to the seam on the stock BCX body. The replacement single-piece windshield helps to draw focus away from the seam. Unfortunately, the misalignment of the halves at the front is pretty obvious, and I wish I'd done something about it, early on. Oh, well... Life goes on, imperfections and all. Nevertheless, I think it looks pretty darn kewl! And now that I'm okay with it, I'll be making another CooP Debbil Gal decal for the nose. That oughta improve performance and...uh... keep it up longer!

15 second video, 700Kb, .wmv format

 

OBLIQUE OBSERVATIONS Throughout this article, I've pointed out some of the kit's "rough edges". I've done that mainly because such things might come as a complete surprise to a naiive customer, who expected a Tamiya-like model kit. To put this in perspective, it's important to realize that is a cottage industry kit, graciously made available to a small niche market of hobbyists. If there were a sizeable market for this kind of thing, you can bet that the big production guys would be all over it, pouring megabucks into producing snap-together RTF versions at bargain basement prices. But they're not. In a hobby like this, it's the rare hobbyist who recognizes a need and acts on it, because it's something that they want. If we're really lucky, they share the results of their labor and talent.

Yes, this kit has some rough edges, and that's not surprising given that it's extremely difficult for a one-man shop to do it all. And I mean all-- the documentation, the business end, the shipping, the customer service, the production... I've been a "customizer" for quite a while, done my share of vacuforming, resin casting, etc., etc. Many years ago, after a brief initial stint selling resin castings, I swore I'd never do the biz thing again. Besides the odious bizstuff, there was waaaay too much time-consuming finish work to do before I'd feel comfortable shipping-- and it was the kind of stuff that I'd normally be willing to do once, for the prototype. Doing it 2 or 20 times is a real downer. Clearly, you can't take this kind of approach if you want to stay sane and have a life. If I'd taken the sanity-saving approach and produced vacuformed kits of my knight's armour for dolls (as someone once suggested), you can bet that it would have been 1000x cruder and even less dot-to-dot than the Airwolf kit... and all my time would have been spent dealing with customer service. Not a winning trade-off there...

I'm extremely grateful that Manrow has provided 95% of the work that goes into making a unique and desirable alternate body for the Blade CX. The quality of the wooden form that he created is excellent (very symmetrical & graceful), and the vacuformed pulls show great detail for such a tough, resilient type of plastic. It's a good choice of plastic: I'd much rather have the durable body than the greater detail that fragile styrene allows because I intend to fly my bird! (carefully, though.)

Check out the Airwolf and Mike's other BCX bodies at his website.

11/16/06

 


 

FAMOUS LAST WORDS

"I'd much rather have the durable body than the greater detail that fragile styrene allows because I intend to fly my bird! (carefully, though.)"

Even better, just give me one of those "Undo" buttons that you can press after you've done something stupid.

I'd spent a couple of hours masking and painting to give it a more Airwolfy look, and even cut vents to help out with heat buildup. In the back of my mind, I was concerned with the "fatty" problem-- the controller's red LED indicated that the battery and motor were working much harder than normal to keep it aloft. Although this body does weigh more than the stock BCX body, it had flown very well without the front canopy. The front canopy doesn't add that much weight. The longer front canopy does change the center of gravity, so it's expected that the forward/reverse trim would be affected... but I don't think that's the full explanation.

I took some ballpark measurements with my triple-beam scale (grams):

item
BCX body
Airwolf body
TAIL
14.3
21.2
LIGHT KIT
4.0
0.0
CANOPY
7.2
10.5
BODY WT., TOTAL
25.5
31.7
GUTS
157.0
157.0
BATTERY
43.5
43.5
TOTAL WT.
226.0
232.2
As you can see, there's not a huge difference in weight. However, there's a huge difference in performance. The BCX flies as if it were half the weight of the Airwolf.

My theory is that the length, width, and flat contour of the canopy deflects a good portion of the rotor wash sideways, instead of downwards where it would provide lift. The BCX has fairly short blades that only clear the front of the canopy by about an inch. The portion of the blades' rotation over the front of the canopy would probably be wasted energy: ergo, the motor has to work harder to stay aloft. In contrast, the stock canopy is narrower and slopes downwards at a sharper angle, so there's more clearance between the lower blades and the canopy at the widest part of the blade. I'm not an engineer, but it seems like a reasonable theory... although there's not much to be done about it if you want your Airwolf to look like an Airwolf. The blade length is probably matched to the motor and controller, and using longer blades would probably burn something out.

Nevertheless, I had to play with my theory, and after a quick flight to verify that the fatty problem was real, I removed the canopy and hit the throttle. I forgot to adjust the trim. Ooops! To avoid getting speared in the chest, I dropped her and she plummetted, tail first. Not a pretty sight! The tail fin section had broken off into two large pieces, but there were about ten tiny eggshell-like fragments scattered at the crash site. It's depressing when stuff like that happens, but it's even worse when it happens right after you've painted the mofo.

I try not to dwell on failure and was determined to salvage whatever I could-- knowing that it would be more difficult than regular modeling, where weight isn't a factor (read: no putty fixes to make things pretty). I inserted a rolled plastic sheet between the busted tail and tailfin section, and tried to puzzle together all the little pieces over that. I used tape to fill in the missing sections, and touched up the paint job. Yes, the repair looks like crap, but you really can't tell if you keep your eyes closed. Even though it's repaired and still looks pretty neat overall, I've lost interest in installing the light kit. I'm saving that for E-Flite's alternate military-style body for the BCX2.

So what happened to the sturdy plastic? It's probably a combination of factors. The tail is steep and tall, so the vacuform process draws the plastic pretty thin there. It's reinforced by a face piece, glued around the edges. Superglue is a very rigid glue, and when you kick-cure it, it looks crystaline. I'm thinking that it makes flexible plastic more rigid, and perhaps more prone to cracking than bending (which gives that telltale white stress mark). It's a little after-the-fact, but if I had this to do over again, I'd try assembly with contact cement. Contact cement doesn't provide as strong a bond perhaps, but it's tenacious and has a lot of flex. I used it to attach the bottom edge of the front windshield which is flexed to conform to the curvature of the canopy. It's held up better than the tape I initially used. There are also some really tenacious double-sided tapes used in commercial packaging-- I don't know where you get the stuff, or what it's called, but it seems to do a good job of joining smooth plastics while remaining flexible.

I don't give up easily: I shortened the Airwolf canopy by about half an inch, but it didn't improve performance significantly. As much as I like the way the Airwolf body looks, I prefer the way the stock BCX body handles. If I were more daring, I'd risk my controller and motors with a 3-cell LiPo: The higher voltage would probably make a world of difference in performance. However, that would only mask the issue of efficiency for a while, until it came time to replace those abused parts.

11/18/06

THE FINAL WORD(S) Yep, I don't give up easily. This time, I took the canopy apart and trimmed approximately a quarter inch along the center to make it thinner with a more rounded frontal profile. It's also mounted a bit lower at the front, which creates a greater slope angle away from the rotor and therefore, more rotor clearance. The canopy looks like hell with extra drill holes, glue marks, and trimmed away areas but that's to be expected from trial-and-error mods. The verdict:

Unfortunately, the fix makes it look less Airwolfy, at least from the top and frontal view. Non-coaxial RC copters are probably better suited for the true Airwolf canopy profile because they have longer rotor blades. Unfortunately, the working area of the Blade CX's short blades is smaller and closer to the center rotation, so what's directly under it greatly impacts the blades' efficiency. Therefore, if you want a good-running BCX, your choices for alternate body styles are limited, compared to those for single rotor copters.

11/20/06

1:26 minute video, 3.6Mb, .wmv format