|Wing Area:||Not specified but measured ~330 sq in|
|Weight:||11.5 ozs to 13 ozs|
|Wing Loading:||~6.1 oz/sq ft|
|Manufacturer:||Hacker Model Production|
|Available from:||Air Craft World|
|Motor:||Model Motors Axi 2212/26|
|Esc:||Castle Creations Phoenix 25|
|Battery:||Poly-Quest 1500 3s|
|Servos:||3x Hitec HS-55|
The electric 3D flying scene has become very popular now, thanks to the advancement of electrics as the planes are light, designed more precisely, and the power setups are progressing at an astonishing pace. Precision foamies are making it possible for the inexperienced 3D’er to teach themselves in small open areas like parks, cul-de-sacs, and even back yards without having to worry about smacking the ground once and a while. When the chance came up to review a plane that satisfies two of my favorite interests (epp foam and 3D) I had to jump at it.
The Zoom Zoom 4D is designed by Czech National Champion David Kyjovsky. David has designed other aerobats such as the “2 Cool Bipe”, the “Microbat”, and the Bambula. Air Craft World Japan is celebrating their two year anniversary supplying the electric flying world with many new products and services. Owner David Radford (known to all of us on RCGroups.com as NipponDave) has done a tremendous job keeping up with the rapid pace to bring us the latest products. Air Craft World is one of the premier vendors in the hobby and their service & support is outstanding! Thanks to David for supplying the Zoom Zoom 4D and miscellaneous hardware for this review.
The kit arrived in a long thin box and since it’s made of epp foam it can take the occasional shipping punishment while still maintaining its integrity. ACW’s shipping is really quick in spite of coming from half way around the world. I live in the Chicago area and usually receive my orders within 5 business days. The fuselage, wings, & ailerons are made from high density lightweight epp foam while the tail pieces are 6mm Depron, which is very rigid. The foam comes nicely pre-painted in three different color schemes – pink, green, and yellow. Other hardware included in the kit is the motor mount, control rods and servo horns, hinge tape, and landing gear with wheels.
The builder will be responsible for providing:
The recommended power set for all-round indoor/outdoor performance is an AXI 2212/34 OutRunner brushless motor, Castle Creations Phoenix 10 esc, APC SlowFly 10x4.7 to 11x4.7 prop, and Poly-Quest 3s 1100mah lithium polymer battery pack. For high-power outdoor, I opted instead to install the AXI 2212/26, Castle Phoenix 25 and Poly-Quest 3s 1500mah li-poly pack.
For radio gear I chose 3 Hitec HS-55 micro servos and a GWS 4 channel Pico receiver. I’ve always had good luck with the GWS rx’s and since this will be a close-in flyer, range is not important to this installation.
This is a VERY well-built ARF and I won't bore you by covering every step of its assembly. Instead lets look at the highlights and a few minor changes I chose to make.
The construction of the Zoom Zoom 4D is very easy and can be completely built in an evening, both because it’s an ARF and because it’s a foamie. The control surfaces are pre-cut into the foam and all hardware is nicely cnc cut fiberglass which is light and strong. I found the instructions very detailed in Czech and English with a picture for every step, a nice touch.
I joined the wing panels together using hot melt glue. I used hot melt glue because of my past experience building with epp foam. Hot melt glue on epp, if used sparingly to watch the weight, gives one of the strongest bonds I’ve seen; it also flexes with the foam, and dries in seconds.
Next I used a straight edge to cut a slit across the wing to accommodate the spar. I deviated from the instructions here and used a ½” flat carbon fiber spar installed perpendicular in the wing rather than the thin aluminum rods supplied with the kit. The carbon spar is very strong but let me stress here this is a personal preference and not a “must do”.
When using the stock aluminum rods, it is important that you make sure you scuff the rod first for good adhesion, then glue the entire length of the rod using foam safe CA. If the rod is properly glued its entire length, the foam will be very rigid and bending is almost impossible.
There is not much preparation on the fuselage other than to install a spar, just like the wing. Again I opted for flat carbon fiber but the stock aluminum rods are just as sturdy. Make sure you glue the rods completely with thin foam safe CA and use activator. (Did I say this already? Can’t be too sure!).
The kit came with strong adhesive hinge tape which is a sort of clear “fabric type” tape for attaching the ailerons to the wings.
The tail pieces are the only part of the kit that is made from 6mm Depron. I fit the horizontal stabilizer into the fuse and squared it up before gluing.
The large rudder hinged to the rear of the fuse, as there is no separate vertical stabilizer. A nice little fiberglass hinge set and rod was supplied with the kit, but I cut some time here and just hot glued regular CA hinges instead. (It works!)
At this point the empty airframe was complete.
The kit supplied a cnc cut fiberglass mount that directly bolted to the little Axi outrunner motor. After ca’ing it together I decided I was going to deviate from the instructions a bit here to install a round 1/16” ply mount instead. The fiberglass mount is light but I was concerned that a nose-in or prop strike may knock it loose. The ply mount is a proven one as I used it to mount many Axi motors on my fan fold foamies.
I carefully aligned the thrust for zero up/down and a few degrees of right thrust, and hot glued it in place. Most overpowered 3D planes need a little right thrust (I didn’t say overpowered did I?).
I recommend temporarily taping the radio gear in place with the battery pack you are going to use to get the CG correct prior to cutting out the portions of foam where the gear will be installed. One bit of advice here is that I think the recommended CG is very conservative (read "nose heavy"). In fact I originally thought it needed to be about 1” behind recommendation but after flying the plane quite a bit I prefer it 1-½” behind. I’ll explain this later but for now be prepared when building. Always build your model to the stock CG placement, but be prepared to be able to move equipment, should you find you prefer your Zoom Zoom more tail-heavy, as I do.
If there is one caveat on this plane its battery pack placement. I can’t imagine the battery pack placement where the instructions indicate (in the nose of the fuse) as I would never have been able to balance the plane correctly. Originally I installed it under the wing using Velcro, but I kept moving it aft to find the CG that fit my flying style. I eventually ran out of space as it was in the way of the aileron control rods. Then I moved it to the underside of the fuse until I found my desired CG. (This was all during the flying stage; you may want to do the same until you are sure of what you like.) I ended up cutting the pack into the fuse between the ailerons.
The supplied fiberglass control horns could be installed easily into the foam surfaces with hot glue or CA. The aileron servo required a larger than stock control horn to achieve the desired throw. I used one from another kit I had laying around but you could also extend a stock horn with a piece of 1/16" ply and CA it in place. I installed the servos as indicated. With the HS-55’s I needed about 6” of servo extensions to reach my receiver. You could slit the epp along the fuse to “hide” the radio wiring.
I taped the motor wiring and esc to the side of the fuse rather than cutting the foam and burying it. I did this because I frequently move my motors and esc’s to other airframes.
This completes the building stage of the Zoom Zoom 4D, now that was fast wasn’t it?
The instructions recommend the CG at 105-110mm (4.13" to 4.33") behind the leading edge of the wing. As mentioned, I found this was too nose heavy for my flying style. After experimenting I think moving it back 25mm (1") is still conservative. Always start with the manufacturer's recommendation, but if you find it too nose heavy for your style also, I suggest starting at 1" behind.
For 3D I like as much control movement as possible, especially the elevator and rudder. Always start at the manufacturer's recommended throws:
Recommended Control Throws:
I turned my throws to the maximum available, and used quite a bit of exponential on my radio for 3D planes with lots of control surface area, somewhere around -70%.
My final AUW was 14 ozs using the Poly-Quest 3s 1500’s, 13 ozs with 3s 1100’s. I was hoping for 12.5 ozs but looking at the large wing area and overall size of the airframe it’s not a bad final weight.
Thrust tests in the workshop were measured at 22 ozs, weight is 14 ozs for a 1.57:1 thrust to weight ratio, excellent! It sure felt like it when holding the plane while throttling up. It was time to take the Zoom Zoom out to the field.
I hand-launched the Zoom Zoom first and it took off vertically, no surprise to me as I knew the Axi would perform like that in a plane at this weight. As mentioned above, initially I found the CG too far forward. Trimming the plane indicated to me the CG discrepancy as I could see the elevator in the “up” position as it flew. Trial and error found the CG back about 1" from recommendations. After trimming somewhat correctly I tried some moves; first hovering, very tight loops, a quick roll rate with the large ailerons, and knife edge, which I noticed immediately had very little tuck coupling.
The Zoom required a lot of up elevator to hold a hover initially which again indicated a nose heavy condition.
Hovering the Zoom is quite easy, I like the larger airframe for that reason. With a little right thrust, it required very little right rudder to hold it, it’s pretty stable. Vertical punch out of the hover is just awesome with the Axi 2212/26.
Parachutes are great but with a forward CG they tend to not end up in a hover, more like 45 deg. This depends what you like, as some people like to end up that way. Once I moved the CG more aft the plane ended up more vertical or basically into a hover, the way I like it.
Harriers are done relatively easy without much rocking and little aileron correction is needed. Rolling harriers are excellent as well.
Waterfalls initially were more like tight outside loops until I went to a more extreme CG, then it handled them nicely. Consecutive waterfalls are no problem at all.
Knife edge loops with the Zoom Zoom are great with very little correction as it has almost no coupling as mentioned earlier. A good power system like the Axi makes it struggle free. I still need more practice on them but now I have the plane to practice on!
The Zoom Zoom 4D is not your typical foamie arf, it comes with all necessary hardware and the paint scheme gives the plane a finished look. It would make a great 3D trainer and even sport flyer if you don’t like to 3D. The final cg I like is about 1 ½” behind recommendation on cg (basically at the leading edge of the aileron) but for most flyers that may be a tad tail heavy. The Zoom Zoom 4D flies very well at a slow speeds, a good quality foamie to have in the 3D hangar.
|Dec 08, 2005, 07:19 PM|
Great choice on the motor mounting system.
Looks like a better way to do it than what kit instructions say.
|Nov 05, 2007, 12:52 PM|
how did you avoid coupling in KE flight? My zoom is useless at the manoevure, then again my battery is held directly on the bottom of the fus.
Should I cut away some fus foam to get the battery flat against the wing as possible?
i.e. my batt is too far away from the centre of the wing?
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