Seagull’s MXS-R, released a couple of years ago and still available and an attractive aerobat being a cut above the .40 - .60 size sportster on which the firm initially earned its reputation.
The model is based on the full-size machine used by Red Bull pilots, the ‘R’ suffix denoting the racing version of the California-based MXS Corporation’s aerobat. Like the full-size, the model is an imposing aeroplane which, as we’ve come to expect from Seagull, is very well made using laser-cut balsa and ply, and beautifully finished in Oracover. The latter is a huge bonus, by the way; Oracover is one of the best (not the cheapest, either) covering materials you’ll find, and being polyester-based it can stand plenty of heat, so any wrinkles can easily be removed. Not that wrinkles were an issue here, the quality of the covering was second to none.
This one is for .90 – 1.00 two-stroke engines or four-stroke equivalents approaching 1.20-size. An electric conversion kit is included, too, for which the manual suggests a 50-size, 310Kv outrunner and 60A ESC, fuelled by eight cells. My version plays host to an O.S. 95 two-stroke, but whatever motive source you adopt, this is a model that’s easy to operate thanks to a large, removable top hatch that provides access to a simply cavernous interior. Moreover, the huge cowl will swallow just about any suitable engine, petrols too.

BITE THOSE BULLETS
Although I’ve great respect for Seagull’s products, and while I really like this model, I do wish they would put a bit more effort into some of the finer details, including the instruction manual. This MXS-R is undeniably well made, but ‘well made’ doesn’t mean well engineered, and although the main assemblies slot together beautifully, the niggle list is far longer than it should be. Deep breath... it’s bullet-point time:

  • Although the model has been designed for standard-size servos, the cut-outs are too small for standard Futaba and Hitec units.
  • Pre-drilled holes to accept the aileron horns aren’t deep enough. Here, then, great care is required to avoid drilling too deep and breaking through the top surface.
  • Captive nuts that sit inside the tail to retain the tail wheel bracket bolts aren’t glued in place so will most likely pop off the moment the bolts try to purchase. They’re impossible to fix after the tail feathers have been added, so be sure to fit the tail wheel first. Replace the bolts while you’re at it; they’re too long and not threaded full length.
  • It’s very difficult to get everything inside the spat without damaging the part, so I suspect many builders will enlarge the axle hole or simply cut a slot. In so doing there’ll still be sufficient grip from the axle nut to retain the spat.
  • It’s important to add threadlock when securing the axle retention nut, as vibration will loosen it. Better still, swap it for a nyloc.
  • A thin ply plate is included with the u/c parts, although this is badly illustrated and described as a plywood block in the manual. The plate sits inside the spat to protect the wall when the axle is tightened.
  • Seagull always seems to suggest using cyano to secure plastic parts to a fuselage but this is poor advice, the undercarriage fairings being a case in point. Apart from the potential for unsightly glue spills and cyano mist, adhesion will prevent trouble-free removal of the u/c should the need arise. I used small screws to keep the fairings snug, with matched Oratrim tape to blend them to the leg lower down.
  • The instructions suggest trimming the axles but don’t suggest by how much. I’d recommend 50mm.
  • Cowl-cutting confusion is guaranteed. The manual illustrates different ways of trimming the cowl at the rear according to i.c. engine size, although identical engine fit (firewall-to-prop driver) measurements are provided. In the event my .95 two-stroke didn’t require trimming at the rear so, needless to say, it’s best to fit the engine first and go from there.

Generally speaking there’s nothing insurmountable here for the intermediate or experienced builder, for whom the model is intended, and there are some good aspects worth noting. I like the spat design, which takes care of alignment, the fit of the rudder and stabiliser is sublime, and the pilot and instrument panel really do enhance the model’s appearance. The hardware is good (clevises, horns et al) and the big fuel tank ensures healthy flight times, my .95 enjoying a comfy 15 minutes.  

FIT OUT
Don’t be deceived by that racy, go-faster appearance; technically speaking this is a simple, straightforward club aerobat (albeit on the larger side) that’s easy to fit out. Standard servos suit it nicely (good analogues or sport digitals will do) and in this respect I used Spektrum DS821s alongside a spare Futaba S3152 to push the elevator. Speaking of which, it’s suggested that a single joiner block be used to link the pushrod from each elevator to the single pushrod that continues to the servo. Letting a 9 lb 4oz (4.2kg) model rely on the integrity of a single, small, grub screw isn’t my cuppa. It’s far better to let one elevator pushrod continue to a swing keeper at the servo and link the second using two tight collets bathed in cyano or epoxy.
The engine fitting process is again perfectly straightforward where, cleverly, a two-stroke installation is angled such that the silencer fills the lower air scoop. Meanwhile, the suggested C of G at 4” (100mm) back from the l.e. at the root is a good, safe, starting point, my model balancing bang on the spot first time.
Printing omissions in the manual have the potential to confuse where control throws are concerned. Although the information appears to suggest more ‘down’ than ‘up’ for aileron and elevator, ignore it for these are just the high and low rate suggestions. Experienced pilots will no doubt find the high rates pretty conservative across all control surfaces and therefore increase the throws slightly after a few flights. I’ve certainly done so, whilst adding 20 - 25% expo’ to soften the stick centres.

SMOOTH OPERATOR
Some might be intimidated by the model’s appearance, but there really is no need to be; this is a smooth and precise sport aerobat that any good intermediate or experienced pilot will enjoy. It’s very forgiving, too; far more than its looks might suggest. I pushed the boat out a bit with my choice of engine but I’ve been very pleased with the performance and reliability of the O.S. It’s a perfect match for the airframe to the extent that I’d not suggest anything less than 15cc in the two-stroke department.

Take-off is a simple affair, with practically no rudder correction required during the roll and just a fraction of elevator to hold the nose up until rotation. Climb-out is very assured, and there’s a comfortable reserve of power.
Slow speed handling is excellent, and finding the stall will be a genuine surprise. Here, a gentle wing drop becomes evident only when the machine makes notably modest headway.
This is no 3D aerobat, but if you’ve seen the Red Bull races then you’ll know what aeroplanes like this are designed to do, and I’m pleased to say the MXS-R is smooth, predictable and responds well at the suggested C of G. I see little point in balancing the model behind that suggested, although moving it forward a few millimetres will do no harm.
The model hasn’t been designed to do anything other than club-standard aerobatics, so it’s really at home carving out nice big chunks of sky. There’s a notable pull to the left through the vertical and, although this is easily corrected using rudder, I may make an adjustment at the engine mount further down the line. Fast point-rolls are straightforward, but extended knife-edge reveals a strong desire to tuck in towards the u/c, so most owners will find some control coupling inevitable. Inverted flight needs just a breath of forward pressure on the elevator at the suggested C of G, whilst spin entry and exit is straightforward enough.
Bringing the MXS-R home is another straightforward task, its safe handling characteristics offering plenty of reassurance as the speed bleeds off during the final approach. As you’ll have noticed, the u/c is a pretty meaty affair, coupled with strong spats and big wheels. It’s a truly Tonka Toys approach to landing gear, so you’ve only yourself to blame if anything bad happens when the wheels meet the ground.   

ROCKET IV?
One of my nicest flying surprises in 2011 turned out to be Seagull’s venerable Harmon Rocket III, a pleasant semi-scale club sportster that’s won many admirers over the years and reminded me that the simple combination of a .50 two-stroke and a good airframe can still offer loads of practical fun. I say that because this model reminds me of the Rocket; bigger, for sure, but the similarities are there. They’re both prettily done, are well made, rugged and offer a traditional sport aerobatic flying performance without serving up any nasty surprises.
Seagull’s MXS-R may look like a high performance R/C aeroplane, but in practice consider it a bigger-than-usual .60-size club aerobat. That’s not to take anything away from the model, it’s a really nice machine that flies extremely well and has bags of presence. It may look a bit of a beast, but it’s a delightfully friendly one.

DATAFILE
Name:     MXS-R
Model type:     Semi-scale sport aerobat
Manufactured by:     Seagull
UK distributor:     J. Perkins Distribution, www.jperkinsdistribution.co.uk
RRP:     £214.99
Wingspan:     65.4” (1660mm)
Fuselage length:     56” (1418mm)
Wing area:     5.3sq. ft. (0.5sq. m)
All-up weight:     9 lb 4oz (4.2kg)
Wing loading:     28oz / sq. ft. (8.5kg / sq. m)
Functions (servos):     Aileron (2); elevator (1);
rudder (1); throttle (1)
Rec’d engine:     .91 - 1.00 two-stroke,
    1.00 - 1.20 four-stroke, or 50-size 310Kv electric motor