Multiplex Blizzard

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Multiplex Blizzard

The Blizzard is sleek, efficient, high performance model; designed for slope soaring or high speed flying. The powered version will climb vertically rapidly, but reaches maximum speed (100mph+) in a dive with the motor off and the prop folded. It makes 'The Whistle' characteristic of a moulded glider as it glides past at speed.

Like most Multiplex models, it is made of Elapor, which is similar to EPP. The Elapor in this model is a lot harder and stiffer than Multiplex’s other models, with a smoother surface. The toughness of the Blizzard is seen as a big plus for those who slope soar and who lack a soft landing space. Apparently the same foam beads are used as for other multiplex models but more are used so there is less room for them to expand in the mould and the result is a denser foam.

Span is 1380mm span, which is sufficient to give it stability, yet small enough to facilitate a fast roll rate and make it easily transportable, even if the wing is left attached.

POWER TRAINS

Multiplex suggests two

  • Himax HC3510-1100. 250 watt Electric RC Brushless Motor: KV: 1100, Weight: 89g (3.18 oz)
  • Higher specification motor - Himax 3516-1350 350 watt: KV 1350, Weight: 134g, (4.7oz).

Both use a 9x6 folding prop with a 40mm spinner. The spinner has a hole in the front to supply the motor with cooling airflow (there are also exit holes in the fuselage under the wing)

Other motors that have been used successfully:

  • Scorpion 3014-16
  • Turnigy AerodriveXp SK Series 35-36 1400Kv / 470w (with the Multiplex 9x6 folding prop, this pulls about 280W from a 3 cell pack, which is enough for vertical climbs)

The model is marketed as being for 3 cell lipos, around the 2100 to 2500mah size, however some people are using 4 cell packs and up to 600W motors. The fuselage will fit a 35mm wide battery between the canopy latches or about 40mm if the latches are removed. There is about 30-40mm of height for the battery, depending how the wing servo plug is done. (see Building, below)

HOTLINER, WARMLINER or SPORTLINER?

The multiplex advert for the Blizzard describes it as a hotliner, which has provoked heated debate because although this model is designed for rapid climbs and very fast, power off dives (just like a hotliner) the foam construction is not as stiff or as clean as a (more expensive) moulded composite model. A number of people with the Multiplex 'tuning' power set or their own heavier set up, have experienced serious flutter in steep dives from over 500 feet, often when pulling out sharply. Fortunately this does not cause structural failure and so far has not caused the loss of a model.

The foam construction does have advantages over composites, it's cheaper and less prone to damage during difficult (or just bad) landings, and is easier to repair.

If the Blizzard does not truly deserve the title of 'hotliner', it fits into the 'warmliner' category, although Multiplex prefer 'sportliner' (a title not used by any other model!).

HARDWARE

The hardware supplied is excellent and nothing needs to be replaced. The kit does not include the prop or spinner (which is part of the power kit) or the multiplex connector that is used to plug in the aileron servos when the wing is attached. When fitting this connector, the pins should be bent flat, to allow the battery to slide back past the connector. (Unless you plan to remove the wing a lot, it's probably best to just use servo extension leads.)

BUILDING

Building the model is quite straight forward, simply read the plans 2-3 times, with the bits in front of you, then start building, ticking off each step as you do it. All the foam and plastic pieces fit well and are easy to align

The instructions suggest the purchase of a Multiplex 6 pin plug-set to fit into wing and fuselage. In fact this is not essential and it is possible to get away with using normal extension lead ends, with the extraction of a little Elapor from the top of the fuselage above the plastic section that’s mounted in the fuselage. If you are not constantly removing the wing then there are no issues with this. Some who anticipated rough landing on rocky slopes chose to not to use the Multiplex plug, as they felt it would cause damage if the wing bolts were sheared. One person has even converted his Blizzard to rubber bands and dowels, for rough landings.

Some who used the Multiplex 6 pin plug found the need to bend the pins at the bottom, to allow more room for the battery. Using the extension lead method above would allow more room for the battery and even more could be available if one was to cut back the plug-holder sticking down into the battery cavity, before gluing it in.

The cockpit is 35mm wide between the canopy latches, or about 40mm if the latches are removed. The canopy hold-downs are similar to other multiplex models and are easily broken but can be replaced with Velcro at the place where it meets the wing, which is easy and works well. Alternatively magnets, tape or a rubber band can be used.

There are 3 steel ball bearings provided to use as a tail weight to correct for centre of gravity. These can be put in after building, by removing a hatch in the tail.

The Velcro supplied with the kit has extremely good adhesive, and does not peel off the Elapor.

SERVOS

Various servos have been used successfully.

Hitec HS55s fit perfectly but some of us are not happy with their strength and reliability for this sort of application. For a little extra money you can get the HS56s or, even better (same weight and similar money) the HS65bbs.

SG90 or HXT900 9gram servos are roughly equivalent to the HS56.

IN THE TAIL – ONE SERVO OR TWO?

One decision you will need to make before you build is whether to have one servo or two in the tail. Two servos will allow you to use rudder (using v-tail in your transmitter or, if your transmitter does not have that facility, requiring a separate v-tail mixer in the model ). The rudder is not really required to fly this model, as it is not a floater (which would thermal better if the wings were kept close to level). It is a fast flyer and putting it into a bank and pulling elevator is just fine, and quite fun.

However fitting two servos halves the load and provides some redundancy; if you have a servo failure the other was likely to allow you to land safely – and there is no extra weight as without the servo you would need one of the ball bearings in the tail anyway. Using a second servo in the tail requires a second lead to come up the tail, which requires a little soldering or digging out of the route for the leads, but this can be done easily.

It is possible to add the second servo post-build, provided it does not interfere with the wire of the first servo you put in, and you don’t mind cutting a slit along the fuselage for the wire of the second servo (or running the wire on the outside).

The tail servos stick out of the fuselage and cause drag. They could be fitted in the rear of the fuselage cavity under the wing, and push-rod 'snakes' lead through the channel in the fuselage.

SOLDERING

Some soldering of servo extension leads is suggested as being required, however you can get away without it if you simply have the right length extension leads and you dig holes in the Elapor for the plug/socket joins. This allows post-build servo replacement to be done without having to re-solder.

Unless you are happy to have your receiver not be accessible after building, have the servo leads that go in the fuselage long enough so they can reach the receiver at the canopy hatch. Then push the receiver all the way back behind the wing. There is a hole in the bottom of the fuselage for an antenna to exit.

GLUING IN THE FIBREGLASS RODS

Some people say the gluing in of the short fibreglass reinforcement rods onto the wing was difficult but it's not too hard with the correct technique - it does however take an hour or two. Use medium CA (thick CA is too thick and thin CA is too runny). With the leading edge of the wing towards me; put the medium CA in the groove, put the cut piece of fibreglass in the groove and press down it down at the LEADING EDGE with an implement such as a screwdriver or the back of a knife. (NOT fingers or they will stick!). Then use an EYE-DROPPER to drip one drop of accelerator onto the fibreglass at the LEADING EDGE ONLY end. When that hardened a little hold the other end down with a screwdriver and apply a second drop of accelerator, at the far end.

It is VERY important that you do this work with PLENTY of ventilation.

After the carbon spars are glued in, you can run some thin CA along them to ensure the sides are securely glued to the wing - this improves the torsional stiffness of the wing.

Build Photos

Blizzard8.jpg Cutting out the cover for the second tail servo. Blizzard14.jpg Tail servos fitted in place.

Blizzard9.jpg
Fibreglass rod reinforcement of the cockpit sides - multiplex have obviously learnt from all the EasyStars that have broken here - but note that the rod ends at the corner of the canopy hole, creating a stress concentration. It would be better to fit a longer rod (there is plenty of spare length in the pack) that continues an inch or two behind the leading edge.
Blizzard10.jpg
Soldering the servo extensions to the wing joiner plug. Note that the plug halves are connected - this helps to keep the pins aligned, incase excess heat softens the plastic.
Blizzard11.jpg
The plug fitted into the wing retainer plate. Unless your soldering is very neat, it may be better to glue the plug into the plate before you solder the leads. The circular moulding on the left is where the metal nuts that retain the wing should go. The nuts must fitted before the fuselage is glued together.
Blizzard12.jpg
The plate fitted in the fuselage - don't forget the nuts!
Blizzard13.jpg
Receiver fitted in the rear of the fuselage - note that this installation will not allow the receiver to be removed and refitted! There is a hole in the bottom of the fuselage for long 35/72MHz antennas.
Blizzard16.jpg
Extension leads for the tail servos. You will have to dig holes for the plugs, and may have to widen the slot if using two cables (if you're soldering, you could use common power and ground wires)
Blizzard17.jpg
The receiver, snug at the rear of the fuselage bay. Note the white plastic covering the green plug at the top, and that the pins have been bent to give more battery clearance.
Blizzard18.jpg
The fuselage halves joined together - note the gap at the top front - don't attempt to glue this together or the blue nose cover won't fit (or the motor!). Also note the moulded gap at the bottom for the motor wires.

Blizzard19.jpg The blue plastic nose cover, which adds a lot of strength and spreads the load from the motor. Blizzard20.jpg

Tail

Blizzard21.jpg Large plastic part that makes aligning the V-Tail pretty easy. Blizzard22.jpg Glass fibre rods in top and bottom of the tail halves. Blizzard23.jpg V-Tail assembled.
Blizzard24.jpg The small compartment for tail weights.
Blizzard25.jpg The glass fibre rod on the bottom of the fuselage continues into the plastic tail support.
Blizzard26.jpg And the rod on the top continues over the tail halves.

Wing

Blizzard27.jpg Wing halves joined (top surface)
Blizzard29.jpg bottom surface
Blizzard31.jpg Carbon spars added to the bottom (Note they don't fill the holes, as there is a tiny mount of dihedral)
Blizzard32.jpg Glass rods parrallel to the spars, and in short diagonal slots for torsional stiffness - top and bottom.
Blizzard36.jpg Plastic plate on the top, to spread the load from the wing bolts
Blizzard39.jpg and support the other half of the servo plug.
Blizzard40.jpg Aileron servo, with the nice new, two sided multiplex control horn.

Motor and prop

Blizzard45.jpg All 4 holes are the same distance from the centre, so only two bolts fit this motor.
Blizzard46.jpg A vented spinner is a good idea for this model, the standard Multiplex one is blue plastic.
Blizzard47.jpg Make sure the ESC and wires are fix out of the way of the spinning motor!

CENTRE OF GRAVITY

The diagram shows the CG 50-60mm back from the LE and elsewhere states 70mm, which is about half the chord (!). Many people have tried 70mm and reported that it correct; at this point the model still needs down elevator to fly inverted and gently pulls out of a dive.

Control throws

5mm of elevator travel in each direction is plenty.

POST BUILD MODIFICATIONS

Almost anything in this plane (possibly excluding the servos) can be easily changed post build. This includes the whole power train, adding or removing tail ballast, strengthening the wing and even adding flaps.

ERADICATING FLUTTER

It is important to note that some flyers have not had problems with wing flutter. You may choose to do nothing until after a test flight. I suggest you test fly BEFORE you paint, so that any tape you put on can go onto an unpainted surface. (However put some coloured tape on the wings tips before first test flight to ensure you don't lose the plane in the sky. When it's white, it's VERY easy to lose.)

There have been suggested methods of minimising or eradicating flutter by using cross-weave fibreglass packing tape on the wingtips and there is now an additional sheet produced by Multiplex and put into their kits showing how this can be done.

See http://www.rcgroups.com/forums/showthread.php?p=11035499#post11035499

A problem with this suggestion is the strapping tape will very perish in the sun and the tape will need to be removed, the wing cleaned and the tape replaced. Covering the fibreglass tape with heat-shrink covering film is likely to be a good solution but as yet there has only been a very small amount if discussion about this suggestion. (Most films require more heat than the foam can withstand)

However Reflex1 (see his succinct post http://www.rcgroups.com/forums/showthread.php?t=814980&page=52 post number 766) says he’s solved the problem of wing flutter with NON-reinforced parcel tape.

Flutter has only been reported by power fliers - it does not seem to be a problem in slope use.

COLOURING / COVERING / TO BE SEEN AND MAKING IT SLIPPERY

The model can be easily painted. I simply used domestic spray paint cans from my hardware store, allowing thin applications to dry before applying another, to ensure the paint does not run.

I strongly recommend painting or covering using strong colours as it can be VERY easily lost in the sky. I also recommend making the top and bottom different shapes, to help with instant recognition of orientation.

One contributor advised he covered it with heat-shrink film.

I strongly suspect much of the noise it makes when flying fast is from the lumps and bumps of the herringbone fibreglass reinforcement and other spars. I suspect that heat-shrink film may make it more slippery, quieter in the fast fly-by and possibly allow greater energy/speed retention because of less drag at high speed.

If you have any experience in this regard, please share it.

Flaps

Spoilerons (i.e. both ailerons switched up) can be deployed to slow the model down, and this is sufficient speed reduction for some flyers.

Here is a modification for crow (or butterfly) braking, i.e. central flaps down and ailerons both up. This is achieved this by taping on some 0.5mm aluminium sheet flaps, without having to cut flaps into the wings and potentially weaken the wing structure. This was extremely successful. See http://www.rcgroups.com/forums/showthread.php?p=11054457#post11054457

Another underwing flap mod can be seen here: http://www.rcgroups.com/forums/showthread.php?t=814980&page=68

SO SHOULD YOU BUY ONE?

This plane fills a gap between the EasyGlider and moulded models, it flies like a rocket and (with flaps) lands like an Easy Star.

RECOMMENDATION

Consider what it is you are seeking.

  • If you are after a plane that will fly gently and catch light thermals, this isn’t it.
  • If you are after the fastest hotliner about, this isn’t it.

It lies between the two, but much closer to the hotter end. It is robust, relatively easy to build and flies well if your reactions are good and you keep your wits about you.

It will be more forgiving (and a little less hot) if you use a light power-train, and the good news is you can easily upgrade this later. If you do upgrade it to hot performance it may be necessary to beef up the wings.

If you are a capable flyer and are looking for a speedy but robust model that can grow with your abilities and won’t break the bank then you won’t be disappointed.

If you are looking for the very best / ultimate performance in a hotliner, and have the skills (and environment and luck) to keep a fibreglass model unscathed, and possibly don’t mind spending a bit more money, then go for a fibreglass model. Comparable fibreglass models are the FVK Bandit (see http://www.fvk.de/Englisch/Bandit.html) and the X-Models Mini Blade Electric (see http://www.south-coast-sailplanes.com/planes/minibladeelectric.asp

The controversy over whether the Blizzard is a poor hotliner or a good warmliner has over shadowed the many good reports from those who have flown it as a slope soarer.

See Also