Were it been land-able, this was a moment for a Blizzard. Meteorological winter starts tomorrow, today is gray and near freezing, but the wind is out of the arctic, off to see if slope soaring 22 mile away Mensfelderkopf with the high powered Easy Star and Fun Jet are possible. The wind was at forty five degrees to the slope, so without a motor (pure) slope soaring was questionable. Despite the miserable crash record of our two Blizzards, it’s time to try again.
Two weeks after it was ordered in August 2011 at the local hobby store for Euro100/$150, my Multiplex Blizzard kit arrived. The goal was a multi-purpose, all weather airplane with a cleaned up airframe and lighter propulsion components, for flying on windy days, armored so that could land on our improvised runways, using what I had around for propulsion. To my disappointment, the stock motor mount is for a larger mounting screw circle, none of my motors would bolt right in.
This is an original for the SDSFD year 2012 article. There wasn’t as much to my own airplanes construction as some other reports, check the Internet as other then taping and fiberglassing the nose I didn’t do much to improve mine. This article will cover more of the adventure of flying RC then previous articles.
Like everybody nowadays, I had read about Blizzards on the Internet and magazines. None of them includes airframe modifications, or quotes durability. About half of what was written up they were crashed within just a few flights. I saw exactly two flights, by a standard Blizzard airframe last summer. Those flights, in still air, the Blizzard wasn’t all that impressive for just flying around the patch. It wasn’t all that fast, the speed fell off quickly, it looked like it handled like a pig, it wasn’t much of a glider and it didn’t look all that agile. I’ve seen hot liners fly, that Blizzard, at least to me, didn’t qualify. On closer examination the wing’s leading edge was chipped away, the club members, mostly recent conversion combustion pilots, didn’t have a grip on matching motor/prop/battery. From watching that one and reading I was expecting more of a fast motor/thermal or motor/assisted slope flier then the hot liner they actually can be. So too was the friend that enjoys watching Internet RC videos.
The difference is speed retention when the amps are shut off, evidently a poorly assembled Blizzard quickly slows down even if it was going fast. Experiment with propulsion, get it only half right, they don’t go all that fast. But, get the airframe right and even with the standard specification power they are fast and quiet. Of the half a dozen I’ve seen on the ground, the leading edge of the wing is always beat up, even landing on club flying fields that are as smooth as a golf (igit, zu English yuck) course. My general impression is that they weren’t lasting long. Half the Internet reports include hitting the ground so hard that the Blizzard was a complete write off, and that after very few flights.
Although comparison with building an old style airplane out of sticks and covering would have the veterans laughing out loud, reportedly it does takes some constructions skills and about a dozen hours to assemble a Blizzard. Quoting from my book for mostly beginners “So, You want to Fly RC” My RC airplanes take longer to assemble, and last longer then anybody else’s, because they have to. My Blizzard took about twenty hours to get to the first flight, but, maybe three hours of that were motivated by delusions of vanity, I spent more time sanding then strictly necessary. Three times before the first flights I fiberglassed and sanded.
Speed Costs Money, How Fast Could I Go
Ever since the bottom fell out of construction 2006 I’ve had plenty of time, but a problem with cash. Even if I had money, I’d enjoy the big RC flying swap meets at Lampertheim Western Germany the first Saturday in October and February, where one of the considerations for the Blizzard was; What servos? And can I find an affordable i.e. used, motor/prop/controler. I went looking for a beat up, but complete, airplane to strip for parts. What I bought was new old stock folding propellers, lots of other bits and pieces and a Fun Jet kit for my total day’s outlay of Euro224/$314-, but no Blizzard.
You can get better servos then (8) gram HiTeck 55s, they just cost more money. That Multiplex Gemini I put together for a friend the previous spring was a turning point for both of us. We could have used HiTeck HS-55s. But, he spent the additional money for four HiTeck HS-65 (11) gram servos with their karbonite gears. What an improvement in controllability!
I secured a folding prop assembly, clearanced the nose some and we worked through the propeller selection together. Interestingly, what gave the most power wasn’t what he wanted, a little less thrust with longer flight duration from a smaller, less likely to hit the ground folding propeller was the most satisfactory. Even if the folding blades kept getting shortened on some landings (when the tips hit the concrete all weather farm road), the difficult to armor nose was treated with fiberglass and paint, and the landing tore out after forty put down landings in the long grass. What a magnificent, close in on little wind days, flyer the Gemini is! However, mid forties with a chess like office job (which ruins reaction reflexes), with the (125) gram Tuning combination and 3S 2200 mAh LiPos it’s too fast for him.
So, the Blizzard kit languished on the shelf while I fiddled with a Fun Jet Lite kit I bought at the twice a year big RC swap meet. Christened Zorg, it might as well have been named “39 and Holding” as that is what I paid in Euros ($55-) for the Fun Jet airframe kit, or less then what two good, high resolution and stronger gears servos (of three or four required) for a Blizzard would cost at Euro24/$33- each, if they were new.
The Mystery in a Used Airplane
Finally able to come to some conclusions about the Fun Jet Lite after the first wind in months, I turned my attention back to the Blizzard. I had about made up my mind to use (18) gram HiTeck HS-81 servos I had left laying around instead of buying ones in the (8-11) gram standard size. It was just a question of economy, cutting out the foam takes minutes, but HS-82 are thicker then the wing, and they would fit right into an Acromaster… Bored, at this point in the year it’s four hours between when I get up and the sun comes up (daylight from 8 am to 5 pm), I put in an Internet search for something to read, a damaged Blizzard, complete including motor/prop/controler, came up only fifty kilometers away for Euro60/$82-. Well photographed, one could conclude that the owner wanted to represent it for what it was and just wanted something back for his investment.
Although suspicious because it had been on E-Bay for two months, mid December 2011, at an imposing duplex indicating well above average financial position, within commuting range of Germany’s Banking center of Frankfurt am Main (think of a Los Angles like mix of wow and yuck, let’s get back to Wiesbaden, or San Diego as quick as we can get through traffic) and yet back against the hills (land is so expensive in Germany that a single family residence there would indicate millions), I gave the owner the asking price without bargaining. I didn’t want to insult him, that motor/prop/controler combination alone cost Euro115/$155- new. Also mid 50s, too many airplanes, the Blizzard was to fast for him, he was ok with the slower flying ARF stuff he had gone back to flying. The Blizzard must be flown faster then the previous “floater” type airplanes from Multiplex.
Back in my basement, on the first good look the single tail servos was an (8) gram Multiplex Nano-S. The Nano-S leads are longer, the quality control may be better (they all center at right angle to the case, which is not to be expected from HS-55s, none of them have ever double centered, which has in the past been encountered with HS-55s a decade ago) and they are a different color, but otherwise they are likely the same as a HiTeck HS-55s. That having just one servo hanging out in the breeze moving both of the V tail control surfaces as an elevator, instead of two separate ones so that, on separate channels with a computer radio, they can also function as a rudder, was one of the problems the previous owner reported with the airplane. The little compartment in the tail had all three ball bearing balance weights.
On pulling the motor the prop looked just fine. Gluing in the three motor wires resulted in one of them already having split insulation, another one tore on removal, easily fixed with just electrical tape. With the external “Bell” of outrunners checking if the 5mm shaft is true is partly includes observing the gap between the turning magnet housing and the fixed part, it looked perfect, the bearings turn smooth, even if the magnets have very little ,“cog” to them typical of “affordable” magnets. Some idea of production date is that May08 quality control sticker on the motor controler.
The motor controler is a simple one from Multiplex 2-3 LiPo rated for (54) amps, the latest ones with adjustable timing are better.
The folding prop assembly didn’t have a mark on it.
The canopy’s front was chipped off, the hold down clips taped on. The fuselage at the canopy was spread, the sides broken at the opening, since the fiberglass reinforcement normally runs straight and is curved, it was bent about (5) degrees up.
The wing looked ok, even if it shows a couple of landings and having one wing side nearly broken and repaired just past the front spar. To my surprise it had two of the better Nano-S Carbon servos, and at least he did a decent job of soldering them to the green connector, even if a crash had stripped the insulation of one wire.
No doubt, just as the owner described, he wasn’t flying fast enough and it stalled on landing, at least a couple of times as it had been glued back together and broken repeatedly.
Even if The Blizzard is in the transition from motor assisted thermaler to a hotliner (see the debate in the Internet) it has to be landed faster, at least twice as fast as an Easy Glider Electric.
To me a hotliner is a high speed, low drag airframe that retains it’s velocity, i.e. a pylon racer that doesn’t fit into any standard racing class. Requisite for going fast is stability, the airplane needs to fly itself, the pilot must be able to concentrate on rounding the pylons and maintaining a smooth energy efficient flight profile. By that standard the year 2000 Brian Buaas Speed 400 pylon racer in my basement qualifies as a hotliner, the Blizzard I had seen didn’t.
The Blizzard airfoil isn’t a Clark Y, it’s thin (8.5%) and must be flown fast enough to create lift. Alone of all of Multiplexes airplanes, The Blizzard is the one that can stall hard, that’s part of the aerodynamic price for a half fast, half speed retaining RC airplane. Any of you pylon racers out there have a numerical estimate of the drag cost of the truncated trailing edges, or if it’s worth the effort to balsa/fiberglass them to a knife edge? I’m flying without anything recognizable as a runway here most of the time, I need the durability of impact resistant foam airplanes, not the thrill of fiberglass fragility.
The original assembly looked competent,
until you started examining it critically. As I started sanding though the story emerged:
1 He had problems getting the fiberglass reinforcement to stay in the channels while the glue dried, it stuck up all over the place. As I pulled the decals off the wing, the blunt ends of the fiberglass stuck out. many places the stiffeners projected above the plane of the airfoil, particularly airflow disruptive, right behind the leading edge. Interestingly, not mentioned in any report, the fiberglass sands down just fine without taking out the foam at the same time. With this denser, smaller poor Elapor standard dry sanding with (180) grit (or finer) works well enough that there’s no need for inconvenience of wet sanding.
2 One thing I fail to understand, why so few “Foamie” Fliers take five minutes with a block of sandpaper to remove the casting flash from the wing and tail leading edges, this one still had them. It creates an unstable airflow, it may go over the flash, or suddenly under it, instead of the smooth curve the manufacturer intended. He must not have had many flights on it as although the fuselage under the canopy was all broken up, the wing only had a dozen notches in it. From looking at a pre-issue demonstration Dogfighter, a wing even with the ground airplane, where the leading edge was chewed up in just twenty five flights, this Blizzard had made about a dozen landings.
3 The wing had been broken past the spars and decently repaired.
4 The ailerons, out at the ends, were still almost as stiff as they came out of the molds. You have to manually flex the whole length of the control surface of foam airplanes to “pre-condition” them (all it takes for Blizzard dense Elapor is twenty up and down cycles, some other airplanes take more like a hundred times), these long thin ailerons weren’t moving much out at the far ends from the center mounted control horns. Without the elevons acting as rudders he would have lost a third of his yaw control, and another third of the roll at the ailerons.
To my surprise, the two aileron servos were (11) gram Nano Karbonite i.e. HS-65s. But the servos weren’t even glued in! Those little squares of tape included with the kit are insufficient to hold them in position over the service life of the airplane (I wouldn’t even trust them for the first flight), they were no longer in plane with the wing. That wing is slightly thinner then the servos, glue the flanges in! I am used to seeing that with Easy Stars, but…
On examination of the instructions another handling ruing error was found, the ailerons need more then twice as much up travel as down. Installing the aileron servos at right angle to the wing would give about balanced up and down throw resulting in a slewing to the reverse of the input of an airplane.
The worst flight killer, also the hardest to see, was that the cast hard plastic tail carrier and the two foam elevons were miss-aligned. The resulting unintended up-tilt of the rear flying surfaces decreased the angle of incidence (z. Deutsch Einstelle Winkel Differenz, kurz EWD) by about (2-3) degrees (intended is that the wing angle up from the tail one degree, hard to measure without form fitting tools), which must have turned this individual Blizzard into a pitching beast to fly, and a frustration to land.
I can’t confirm it, but the velcro of the broken up Blizzard to hold the battery was centered under the hatch. To get my Blizzard to balance with a (185) gram 2200 mAh LiPo required centering it under the forward wing spar about (5) cm (two inches) further back. The wrecked one may have been flying nose heavy, even with the receiver all the way behind the wing.
Although I haven’t yet experimented with the Blizzards balance point, typical, although very rarely mentioned, is that although long thing wings have better efficiency, the balance range is much narrower. Think one inch wide for an Easy Star of Twin Star II, and maybe a third of that for a Blizzard.
No, I can’t visually define just 1 degree, and I don’t know anybody that can. The determination that the two tail fins were installed angled up from intended was made by comparing them with the new parts installed deburred. By the time it slowed down enough to land, it tip stalled. For a vast majority of conventional, tail in back of the wing airplane, the tail MUST push down. Aiming it up results in an aerodynamic condition comparable to being tail heavy. At low speed you need all the aileron you can get, his didn’t have enough.
With my piloting skills I might have done better then the original owner flying it, but not much. No wonder so many of the Internet Blizzards were quickly wrecked.
The sanding and investigation took long enough to watch the movie “Back to the Future”. My Blizzard will be named Marty McFly.
Conclusion about the used airframe; For my Euro (60) and the half as expensive drive, I have a decent motor/prop/controller that goes for an Internet Euro85/$120- (previously Euro135), one modest, but durable and serviceable (8) gram servo, two much better resolution (11) gram servos with stronger gears, the wing may be reconditioned for lighter flights, but the fuselage and canopy shall be junked. The cost of the replacement parts (fuselage halves, tail plate, two tail fins, fiberglass rod, canopy and clips) so nearly equals the price of a complete kit that if I want a second Blizzard, I’d just buy another kit. I used to be employed in computer driven manufacturing (aircraft hydraulics, landing gear and pipe welding), dissecting this airplane reminded me of picking apart a sub-contractors operation, it sort of looks ok, but what are they screwing up? If he didn’t live so far away I’d go by and show the gentleman where he went wrong. He seemed like a decent sort that would have enjoyed having a couple of Biers in the basement while we put things in order.
Out of Two, Lets Put One Together
As I started putting my new Blizzard together, I had the most frustrating super glue experience of my life. Once the CA sets it holds for ever, but it can take hours to set on this dense Elapor foam! Without activator ready don’t even start, just as the Internet reports stated. What follows is where my experience deviates from the, read all about it, on the Internet.
Attempting to smooth out the used wings airfoil, I experimented with lightweight waterbase spachtel filling in at the fiberglass reinforcing. The spachtel wouldn’t effectively go into and stay in the gaps until you forced it in by mounding it up, it didn’t add much weight, and it didn’t fill in much. There are better catalytic materials, Aircraft Spruce in Corona California is a first rate source, but I’m here in Western Germany, and the good stuff never is cheap… The hard plastic center wing joiner of the used wing stuck way above the surface of the foam (about (2) mm), it was sanded down and spachteled, just to see how that went. The ends of the hard plastic sanded down, but spachtel isn’t the material for filling in that type of gap. That type of abrupt edge with the airflow going into it is very disruptive to airflow, particularly for a medium speed airplane like the Blizzard it can really slow the airplane down, it’s a place for improvements.
When I started with the servos removed from the used wing it weighed (222) grams. After three hours of sanding, spachtel, heat shrunk on packing tape over the leading edge and the gaps at the spars, and two layers of (20) gram per square meter (five ounce per square yard) fiberglass held on with hardwood flooring paint on the wing’s bottom side outboard of the servos, I had a much smother, much more durable wing that weighed (234) grams.
One of the worst moments of my handworker life was switching from construction to CNC manufacturing (cause, weak knees), the worst of it was deburing. Not only do the flying surface cores need to be de-flanged, so do the insides (the side that gets glued to the foam) of the wing joiner plate and the plate that holds the “V” tail together. It doesn’t seem like much, but those little “fins” of plastic can cause the wing joiner to flex up while the glue slowly sets, resulting in them being uneven with the wing, and no doubt are what forced the front of the rear control surfaces of the used airplane up. That’s angling the front of the tail fins up resulting in the wing flying with a negative Angle of Incidence (angle of incidence is figured with the wing as the referenced to the tail) is all it takes to convert a worthwhile flyer into a instable airplane that quickly becomes a junker.
“V” tails first came into use at Estancia in Costa Mesa about 1995 when batteries became effective enough to start flying electric powered pylon racers there. Brian liked them, me, stuck with fragile balsa, I realized that aligning them was difficult when they were new, and progressively worse as they were repeatedly repaired. Breaking the tail of a balsa/shrink on covering airplane is a routine event, I never did like building V tailed airplanes from pieces. I repeatedly trial fit the new Blizzards tail, it fits even. After deburing, my wing joiner sticks up less then half as much above the plane of the wings foam compared to what the used one did. That need to debur the hard plastic parts is something that doesn’t get mentioned in the other Internet reports, it took about five minutes. That attention to critical fit and function are why, even if my airplanes look like they were originally engaged by a Circus that went bankrupt, they fly well.
After thinking it through, as I noted in my book for beginners, you get one easy try to assemble a foam airplane, I cut up and discarded the fuselage and tail. As fragile as an individual foam piece seems, there was no way to remove the foam plus fiberglass plus glue from the hard plastic intact. The foam sticks so well to the hard plastic that, scrounger that I am, I threw out the tail joiner too. Other then the wing and nose, the original airframe was beyond economic recovery. If I want a complete second Blizzard, I’ll buy another kit.
Although the leading edge of all my Multiplex airplanes gets treated with heat shrunk on packing tape (the change to the airfoil be impeded), and every other Elapor airframe the hinges were also tape reinforced, with this denser foam of the Blizzard taping the hinges doesn’t seem necessary, I left the hinges of both the wings as they came, just flexing them enough to make them lose. It’s at this type of construction I lose faith in reports made after just a few flights, how long they will last…
One oddity, the motor is a HiMax 3516-1350 (new retail on the Internet Euro35/$50-), which although that is the current Multiplex USA offering, is not available on their Brantuas Virtual-Dyno. Hey Editor, or our ace former Portuguese Airline pilot, care to put in on your virtual-dyno? It weighs about (135) grams, or typical for the 35xx HiMax series. Current set price for the motor/folding propeller/controler is Euro85/$120- down from Euro (125).
I Don’t Know Much about Aerodynamics
Oh I know the basics included in flight school, but even though my degree in Civil Engineering from SDSU included fluid mechanics and a lab, every time I look at just airfoil design; The complexity is mind boggling, I let somebody else deal with it. But, I suspect that if we wanted to design an airbrake for this F5D size airplane, that it would look a lot like those one, or two, servos sticking out in the wind in back. As great as these inrunner motors are, I suspect that tucking the servos inside and using a smaller motor might make balance at a lower weight (even though the thrust would drop too, that could be recovered by going from 3S LiPos to 4S LiPos), to retain speed a little better. That changing the aerodynamic shape is aeromodeling. Reinforcement will be using lightweight spachtel and fiberglass to clean up the wing. Armor will be additional fiberglass and carbon fiber for the fuselage, which thanks to the used example, I now know about where it is needed.
One thing I did spot, the wings of our belly landed RC airplanes get abraded at the “touch” point where they and the fuselage meet the ground. The Blizzard’s wing’s leading edge is thickened from right there on out to the end, whereas normally fast airplanes the whole wing tapers in both width and thickness. That also way improves the resistance to being worn off by contact with weeds. See above, if I wanted a fast, fragile, F5D hotliner, I’d need a runway to land it on. If I wanted just speed, cheap and dirty, I’d build a Multiplex Fun Jet Ultra and stick this motor in it on 4S. But, that’s another project.
After thinking it over, I decided that for the fuselage to spend the Euro16/$23- for another Multiplex Nano-S servo to match the one that came with the used fuselage and go with a fully controllable tail surfaces. Without a lighter motor in front the weight in back is needed for balance anyway. Having recently acquired not just one but two (135) gram outrunners that bolt right in changed my propulsion plans. Together with the additional servo extension that made for an additional Euro20/$28- over the minimum. With a single servo a HiTeck HS-55 might have been a slight savings over a Nano-S, but the 55s often don’t center at right angles to the case making correctly installing them as a pair impossible without a computer radio that can separately zero them. While that not being a pair servos is merely inconvenient with wing servos in an airplane where you are expecting indifferent performance (you wouldn’t notice it in an Easy Star II or Easy Glider), with this V-tail it was essential the servos match. So, one tail servo in modest, but reliable, quality plus a servo extension would have run Euro18/$40-. Were I buying new parts, that would have been Euro40/$56- for two decent, they center to the case at right angles (for instillation as a pair), have long leads, reliable (11) gram servos and their required extensions.
Although the owner of the used Blizzard’s mechanical assembly skills were about average, he seemed to have a grip on soldering. I thought about installing those desirable, moderately expensive HS-65 like Nano-S Karbonites in an Acromaster, but things were already set up and soldered to the green connector, the matching fuselage side was ready, I put them in the new wing. So much for throwing an airplane together, installing the servos and taping over the channels left from the wing spars took an hour. Things like verifying that angling the servo arms forward one tooth resulted in just the (14) mm up and (6) mm down aileron travel recommended. If I trash the new wing I’ll put servos in the used one, for now it sits reconditioned but unused.
When it comes to differential, out DogFighters need a quarter more up then down to roll axially, the same for the Twin Star II. They corkscrew in the opposite direction from the aileron input without the differential, but they still fly ok even if the differential isn’t put in. That’s a Up/Down (1.25:1) ratio. For the Blizzard the ration is (2.3:1), more then usual, they would probably be a tough flying proposition without differential, even more so without being able to separately control the elevons as a rudder.
Although the fuselage equipment compartment was treated to a resin held layer of (20) grams per square meter fiberglass, that isn’t enough, the inside received a layer of (40) grams over the bottom after the halves were glued together. The outside front of the fuselage was treated to three layers of (20) grams fiberglass. Layered because that results in progressively less stiffness with a minimal transition from foam/fiberglass to just foam.
With the two tail servos finished installed, no motor or wing extension servos, the nose cone installed, the fuselage ready for more fiberglass weighed (233) grams, of which about (3) grams is additional internal fiberglass. Together with that ridged nose cone, the fuselage from the nose aft to behind the equipment compartment will be a solidly fiberglassed into a rigid foam core assembly. By layering the transition to the flexible tail avoids an abrupt change in rigidity, that would otherwise be a stress breaking line.
Wow, Better then Expected
I built this thing for windy days. That Sunday, the 22nd of January 2012, it was blowing about fifteen km (ten miles) per hour, and down slope to the adjacent hard surface farm access road at that. Off an on light rain, well above freezing, yesterdays snow had melted and soaked in. A desicion was made to not make the first flights with the friend’s new ParkMaster, but to try my Blizzard since, for the airplane, by my expectations, conditions are actually ideal.
Both of us outwardly reserved (what would you expect from a lawyer and an engineer?), we are both active in life all out of proportion to exterior behavior, or occupation, the friend and I have been flying together for a year now. Although we weren’t as excited as with his then new DogFighter last summer, we were in anticipation mode. At half amps it just flew right out at a slight climb. I didn’t even rock in the wind, no tendency to turn with it at all. A little more amps to get some altitude, four trim clicks right roll and it flew as if it always had. Even at half amps that neat Pfiffen (zu English whistling) that comes with a fast streamlined RC airplane could be heard. After a couple of short climb and turns to get the battery ready, I hit it for all it had, a measured (37) amps at (11) volts on a peaked battery on the bench at (15) C, the battery’s likely 45F temperature here and now would cut that back fifteen percent, the pa