You know, on the face of it any reader of an aeromodelling mag these days could be forgiven for thinking that world domination was being sought by the manufacturers of electric powered models. The advance of ARTF kits and brushless motor technology certainly caters to the whims of many, but what about died in the wool petrol heads? There are still aeromodellers that actually like to get oily and go home stinking of burnt Castor you know! Well CML stepped up to the plate and sent in a true slimers model for review and it's no diddy little .40 powered sportster neither I can tell you.
The Top Gun Javelin 90 is a big model. Granted it's not in the league of a 1/3 scale aerobat, but for a sportster it's plenty big enough.
Here's the full spec:
· Wing Span: 61 3/4in (1570mm)
· Wing Area: 721sq in (46.5dm sq)
· Weight: 6.8-8.5Ib (3.5-4.1kg)
· 2-Stroke Engine Size: .60-.90
· 4-Stroke Engine Size: .90-1.20
· Radio: 4 channel (5 servos)
· Length: 67in (1700mm)
When I first saw a picture of it in the CML catalogue, to be honest I wasn't impressed. The photograph was taken at a peculiar three quarter view angle and I glanced past the model dismissing it as some variation on a large 'Astro-Hog' type aircraft. However what I now know of course is that the catalogue photo belies the truth.
The Javelin 90 is a true 'Patternship' styled model, manufactured in Thailand under the name of the Topgun range by the miniCRAFT Co. Ltd, it is a model in much the same vein as the prolific Majestic design of Christophe Paysant Le Roux that made so much money for Kyosho a few years back. Shorter in the moment arm than a true F3A machine with control surfaces large enough to hint at some possible 3D performance, but billed as a sports aerobatic model.
The wing is balsa sheeted over a white foam core and the fuselage is constructed from high quality balsawood and ply with a foam 'turtle' deck at the fore and aft of the cockpit.
The fuselage is very deep and accentuated even further by the large belly pan which brings the wing up into a mid mounted position rather than slung underneath. If ever there was a model for the knife edge fiends out there.....
Although one piece when built, the wing is fairly easy to transport around with most of its large area coming from the broad root chord rather than the 1570mm span. The fuselage on the other hand is a fair chunk longer than the wing and with the big tail feathers in place you have to consider the size of your car! The heat shrink film covering is excellent save for the usual ARTF practice of using said film and not sticky trim for the trim lines (more on this later) and the fibreglass cowling and spats are certainly robust enough for the job and very well finished. There are bits of hardware individually packaged all over the place. The engine mounting is cast Aluminium alloy and is truly exceptional for an ARTF. As is the spinner assembly with its machined backplate. The main undercarriage is a two piece affair again from heavy alloy and a tidy moulded bracket is provided for the sprung tailwheel assembly. On the face of it the Javelin 90 certainly 'feels' like a quality bit of kit, this even despite the fact that the 8mm square pushrods supplied in my kit were made from soft, useless and very bendy 8mm square balsa!
As is common these days I was able to dry assemble the model on the coffee table within minutes of opening the not inconsiderable box. It certainly looks the part and I'm a great believer in the adage "If it looks right it will be". If only CML hadn't used that dodgy picture in the catalogue I might well have had one of these sooner!
That said, sometimes looks can be deceptive and I soon began to wonder what usual ARTF problems and shortcomings lay in store for me. The vague English in the Thai instruction booklet was enough to get me wondering and as the build progressed it was clear that the instruction booklet was going to be about as much use as a snooze button on a smoke alarm! Let's be honest though, when you've hung a few ARTF models together (and the Javelin is certainly no beginners tool), do you really need them save for a few dodgy dimensions and the CG? On this model I found it was best to consider them as 'suggestions' rather than 'instructions'!
Construction starts with the wing and with a quick splash of Cyanoacrylate you've only gone and stuck the Ailerons on.
Servo choice needs to be considered carefully. This is not a small aeroplane and the control surfaces are quite large. Couple that with a motor at the higher end of the range providing increased speed and aerodynamic forces and you will need something a little hotter than stock on your wiggly bits. I used Futaba 9202's in the wings which have never let me down with their 7.7kg/cm torque at 4.8 volts.
A short extension is required to reach the servo box via the built up balsa channel through the wing.
Having removed the covering from over the wing servo boxes I discovered that there was nothing in there to mount the servos to! This was contrary to those instructions I mentioned earlier so I had to add some spruce bearers to screw the servos in. Later in the build whilst fitting the tail, four pieces of ply fell out of the fin packet which were obviously the bits that should have gone into the wing boxes. Too late then though and with no picture of these bits in the kit contents photograph I'd advise you to check yours carefully before you start. Well, more carefully than I did anyway!
The wing is joined by a very large hardwood dihedral brace which was a disappointingly slack fit into the pre-formed wing boxes. I considered shimming it on the top to make up the difference but as there was a set amount of dihedral to add I eventually chose to just 'pot' the joiner with epoxy to take up any float. This took almost 10cc's of glue on each side to get a fit I was happy with so shim away if you're using small tubes of glue. The wing root alignment could have been better as well and there was quite a gap to be filled with further epoxy mixes after joining. Nevertheless, when complete the wing joint is very strong and with the plywood wing bolt reinforcement plate, front wing dowel and built up belly pan in place, work here is done. The belly pan fit and that of the wing to the fuselage wing seat were lets say, a little draughty, with more epoxy required to close up the gaps left behind.
When mounting the wing to the fuselage I again ran headlong into the poor instruction booklet. This advises you to drill through the holes in the wing bolt plate onto the recipient plate in the fuselage, thereby marking out the position of the captive nuts. However the nuts are already in place and do not tie up with the suggested position for the placement of the wing bolt holes in the wing! Very bad this one. Measure yours twice carefully before proceeding or you'll cock up the wing mounting.
Work turns to the fuselage and fitment of the tail feathers is first. After the fun and frolics of the wing this turned out to be a breeze. Just make sure everything is square or you'll defeat the object of having a 'Patternship' in the first place. Again all hinges are cyano wicks and with a little wire bending for the tailwheel, the empennage is completed quite quickly.
The undercarriage fits very nicely onto the pre-drilled holes and captive nuts but fitting of the spats was a challenge that the Krypton factor would have been proud of!
There is simply no way that the parts supplied in the kit go together in accordance with the instruction booklet. The only thing the spats in the kit have in common with the ones in the construction photographs is that they are White! Those pictured include a recess for the u/c legs and different axle fittings. Even the instructed drill sizes are wrong so check carefully before drilling!
In the end I had to carry out quite a modification to the spats in order to use the supplied hardware and even then I had to add a couple of bits. The resultant mounting is very robust but I tore some hair out over this one and I don't have much left to spare if anything else crops up!
The front end is pretty much dependant on engine choice. I mulled this over for quite a while. With the model dry assembled and a couple of aeromodelling mates round for a beer one evening we unanimously decided that this was quite a big model and a .90 might look a little lost in the nose of such a machine. We ran the whole gamete from the Super Tigre 23cc glow mentioned in the blurb with the kit to the Moki 1.35 alternative right down through the OS BX 1.08 and ASP's copy. Any of these would do the job well enough but I was tempted away from the larger cc's when I unfortunately found some de-lamination of the balsa wing skin towards the tips. Not enough to ruin the model and fair play to CML they did offer me a replacement wing straight away, but it was enough for me to draw a line through the Moki 1.35 and look at the smaller motors. In the end I plumped for a brand new OS 0.91FX having regretted selling mine in a 15 foot span Grob 109 many years ago.
The engine mounting holes are already drilled into F1 for you and the captive nuts are once again in place. These days I am more and more convinced that ARTF installations from Asia are done with perceptibly quieter four stroke motors in mind. The problem, and it is only slight, is that once mounted, the silencer of this very popular OS motor totally fouls the channel cut into the underside of the tank bay along which it is supposed to run. The wood in this area is solid block and it's an easy enough job to cut it away to clear the silencer. Nevertheless, fussy beggar as I am, I did a little geometry to reposition the mount so it lined up. Then knocked out the captive nuts and replaced them into the new holes. Perfick!
No so perfick however is the fuel tank installation. Once again the supplied 16 fl oz tank was different to that pictured in the instruction booklet. A long skinny affair is provided and I had it assembled and in before I realised that no amount of bodging was going to shave the 35mm of the back that was now obstructing the wing! I had to replace it with a 16 fl oz Kavan tank which required the removal of a bit of former to facilitate. Sometimes the smallest things are the most annoying......
Cowl fitting is my forte and I love dressing out the fibreglass for a good fitment. No need for one of those useless clear plastic jobbies here. The cowling is a bucket and it's a simple job to sort it out. I do have another niggle here. With the aforementioned four stroke issue in mind, miniCRAFT have already cut some holes into the cowling for you. Unfortunately one of these is in the front 'air scoop'. Generally desirable to have it removed except that here the standard OS silencer intrudes into this area and you end up cutting further into the already large hole provided. This presents the image of a 'cock up' which resulted in an over large hole at the front. As other parts of the cowling have to be cut out by the builder anyway I can't see the point of the makers doing this bit for you. That aside, the method of cowling mounting is excellent and about the best I've seen on an ARTF with machine screws passing through rubber grommets and proper captive nuts. Very tidy.
The radio bay is cavernous and my JR digitals soon had a home to flap the back end around. The crappy pushrods were ousted in favour of a 6mm carbon job for the elevators and a heavy closed loop for the rudder. I really don't know what the makers were thinking. A .90 powered patternship with bendy matches keeping it up there? Come on!
I tidied up the pre cut holes with proprietary pushrod exits to finish up the job nicely.
I'd got the Multiplex IPD receiver on it's plate and the 1100mAh battery as far back as I could go without cutting another hatch but even then, with the smaller motor as well, the model needed almost 3oz of lead up the chuff to balance her out at the recommended point. No doubt a wooden prop instead of my APC 15x8 would have helped a little and at £14 a pop for the APC it would be a cheaper option too! Nevertheless the model is easily capable of taking the weight and with final checks made it was off to the flying field for some running in before the off.
With a tank through the ringed motor and the needle set just shy of peaking out she was off. Tracking beautifully and sitting at just the right attitude the Javelin flew straight from the floor rather than rotated. Very silky. Straight away it was obvious that the barn door Ailerons were very responsive and I'd not enough expo (you either love it or hate it) for the throw. Totally flyable though even with the mental roll rate! A few beeps of this and that had her straightened up and there was clearly more than enough power in the 0.91 FX to keep even me happy. The Elevator and Rudder throws were nicely balanced, despite the up trim I visibly ended up with. I made a mental note to check the incidence of the wing as the CG passed the dive test first time. There is some rolling against the Rudder in knife edge flight indicating a lack of dihedral and although it's a compromise a simple mix could take care of it. It does excel at knifedge requiring very little rudder indeed. A better pilot than I must easily manage a knife edge loop without bottling on the downward bit or cheating with a flatter wing at the round out.
The model tracks really well and has a totally benign stall. It's a total patternship. It has a lot in common with my Kyosho Majestic except that the tail doesn't sweep as large a cone through snaps and spins. It's much more akin to a F3A machine and it's 3D performance is clearly limited. Still it's not billed as that and a fine sportster it is.
Exits from spins, snaps and blenders is immediate. The preset side and down thrust is spot on for this prop and I only had a little skewing problem from the lateral balance. Even though not yet run in, the OS could take the model vertically from a stalled start up to at least 1000 feet before the grunt ran out. This begs the question as to why you would want to fit a huge motor in the first place. Especially when you consider the tail weight I had to add. Honestly a 1.08 2 stroke / 1.40 four stroke would be as big as I'd go. She settles down very nicely on finals and cruises marvellously down to the minimal flare required for a three pointer. You can even over pull it for a tail wheel first touchdown without a hint of wing rock. The big Rudder and steerable tailwheel makes ground handling a doddle and if your club rules allow, you can easily cruise her right back to your pit area looking as cool as a cucumber. Nice as pie as we say up 'ere!
Now to that damn trim....
The model is very well covered in a high quality heat shrink film. So far as I can tell it's Profilm (Oracover) and that in itself is not the problem. Unfortunately the excellent trim patterns are also made from iron on film and with no 'Prymol' type treatment of the wing covering it just does not stick. The first Blue stripe came of the side with the draught from the first run of the motor. The second piece, a Red bit off the Elevator, was hanging off as I landed from the first flight. The Blue points on the tailplane lifted as the model was wiped down so it was no surprise that a couple of landings later some of those were missing too. Also there was nothing supplied with the kit to carry on the Blue trim line over the cowling to finish this off.
Two things are possible as I see it. Replace the trim with something sticky backed instead of iron on, or do as we used to of old and run around every edge with a clear fuel proofer to resist the still inevitable lifting. I'd obviously prefer it if the former were done for you before shipping. The Javelin 90 flies like a dream but this trim issue along with the other silly 'instruction' clashes along the way do accumulate to spoil the build of a very nice model. I trust CML are in a position to make these simple changes to future kits so that the quality reflects more closely the £189.99 rrp.
The Javelin 90 is distributed throughout the UK by CML Distribution Ltd and is available from any good model shop.
Andy Ellison