Baron’s Hobbies – Online Hobby Magazine

Super Cobra Scale Conversion Kit For The Mini Titan E325

Posted on December 15, 2008 by aaronredbaron

Perhaps it’s a bit ironic that Thunder Thunder choose to model the AH-1W Super Cobra on the Mini Titan. The original single engine “HueyCobra” was the first attack helicopter to enter service, and it was based in a large part on the proven mechanics from the Bell UH-1 Iroquois (Huey). The Thunder Tiger derivative  of the newer twin engine Super Cobra also builds on proven mechanics to transform the pod and boom Mini Titan helicopter into a flyable scale model with a finished look that rivals a static model. Because of the way certain parts snap into place, it appears to this builder the Thunder Tiger engineers must have had this project in the works well before the Mini Titan was released. Unlike other scale setups that slide an existing helicopter into a scale shell, this conversion truly transforms the Mini Titan mechanics into a Super Cobra, with scale details that complete the look.

Mission: Scale Conversion

The AH-1W Super Cobra Gunship conversion kit is intended specifically for the Thunder Tiger Mini Titan E325; it would be difficult to use on a different model. Available in three pre-painted color schemes or unpainted, the conversion consists of PVC body parts, plastic detail parts, scale one-piece landing gear, all the parts to kick the tail up into the scale position, black plastic tail blades and paddles, and a new blade holder. Upon opening the box, I was immediately impressed with the quality of the paint on the body parts. My model came dressed in a dessert camouflage scheme, and all of the plastic parts are sand colored. The plastic parts trees and the detail of parts contributed to my first impression that the kit looked more like a plastic model than any RC model I have built.

Converting The Mechanics

I Choose to use my trusty Mini Titan E325 SE for the mechanics of the Super Cobra. The manual for the conversion kit did not mention the SE, but the only difference between the SE and plastic version (in terms of dimensions) is the front of the battery tray, which I later discovered would require a minor modification. As outlined by the easy to follow manual, the first step is to strip the model of some stock parts.

The landing gear, main shaft, canopy mounts, and tail boom are removed, the tail is disassembled, and the receiver tray gets cut off. With the main gear pulled out, the stub wing assembly that holds the rockets snaps into place below the servos. A new receiver tray snaps into place below the tail boom bracket, a bracket with mounts for the front and back parts of the shell plugs into the canopy mount hole, and the new landing gear is screwed in place just like the stock set. With the tail boom removed, the front boom bracket, servo mount, (1) boom support, tail case and rotor system are removed and reused for the assembly of the new tail.

Kicking the tail up to the scale position really compliments the look on this model, and Thunder Tiger did an excellent job of converting the stock mechanics. A longer belt is employed with an elbow piece to attach the two sections of the boom and support the associated mechanics. At the elbow, the belt runs through two bearing supported pulleys to make its turn, with the pulley on the inside of the belt sporting a toothed design to match the belt. Also on the elbow is a bearing supported bellcrank to turn the tail servo input up with the rest of the tail. My tail servo for 3D, the Futaba 9650, would not fit in the scale fuse, so a Hitec HS-55 was selected for the tail.

The nose of the helicopter gets a positionable Gatling gun to go after the bad guys, but after close inspection of the manual I ran into a small problem. The base Mini Titan frame allowed the gun to fit under the front of the battery tray, and with new side pieces the tray was dropped to fit the battery in the scale body. The SE comes with a one piece battery tray that already puts the battery in a good spot, but leaves no room for the gun. My simple solution was to snip off the end of the battery tray to make room for the gun, and everything lined up better than I could have hoped for. After all was said and done the mechanical conversion had already taken on a new look, and was ready for some skin.

Mounting The Body

After cruising through the mechanical conversion and no paint to worry about, I was expecting smooth sailing on the body. The rear body is separated into two halves which slide over the stub wing and horizontal fin on the boom, and gets screwed to the front canopy mount bracket and the tail boom elbow. Everything went well until I had to join the halves at the seam. A multitude of microscopic 1.2mm self tapping screws are called for to hold the seam. Drilling these holes, and getting the screws to anchor in the thin material proved to be frustrating. In retrospect, I should have drilled all the screw locations first, and then gone back to reinforce where the screws came through. To reinforce the inside, I would simply cut small 5mm square pieces of scrap sheet plastic or thin plywood and glue them to the inside of the fuse at the screw holes. Then, go back and re-drill the holes. With thicker material to bite into, the screws along the seam would not pull out as easily as I experienced in the process of assembly. I was able to complete the seam with the screws, however I was left with extra screw holes that stripped out. I also discovered the top joint along the boom is so close the screws cannot go through without hitting the boom, so I avoided using them there. For the bottom, I choose to use screws instead of tape as called for in the manual.

I completed the conversion in four hours of relaxed assembly, and I had no problem following the well written manual with good diagrams. I have avoided adding all of the little plastic detail parts such as the wire cutters and antennas for several reasons; I find they are the first things to break, and the plastic parts are not painted like the body. After close inspection of the pictures on the box, it became obvious the plastic parts were painted along with the rest of the body. It wasn’t until after I mounted the rockets I noticed how they stood out against the body without paint. For the best look, all the plastic detail parts should be painted to match. I choose to live with the landing gear, stub wing, horizontal fin, Gatling gun turret, tail skid and rocket mounts their factory molded color, and omit the wire cutters and antenna. I may go back and paint all the plastic parts and add the small details when I can paint them.

Sure It Looks Good, But How Does It Fly?

The finished product is nothing short of awesome! Even with the plastic parts not painted, the look is very convincing. On my radio, I started with my 3D setup, and tamed it down for scale flying. I removed the extra pitch and set it for +/-11°, and I reduced the cyclic travel. I also reduced the throttle curves to bring the headspeed down, and double checked my settings for the gyro with the new tail servo. I plan to fly sorta-scale aerobatics with the Super Cobra. Chuck Aaron, who flies the Red Bull BO-105 aerobatic helicopter, earned his helicopter aerobatic certificate (the only one in the US) flying a Cobra, so its not too far off. However, I do want the model tamed down considerably from its 3D incarnation, so I tamed it down accordingly for scale flying.

Already a fairly quiet model, the Mini Titan picks up a new turbine-like sound with the gear train enclosed. The flight characteristics are little changed from before, with my test flight taking place in 25° gusty weather presenting no issues. In fact, I did not have any trouble maintaining a solid hover or holding a straight line even with considerable gusts. The Mini Titan has always been a stable, solid flier. With reduced rates, extra weight and a streamlined fuse, it flies even more solid than ever. No vibrations were noted at all, and the presence in the air is superb. I plan to work my way slowly into flying aerobatics as I explore the flight envelope. The model will be flown similar to Chuck Aaron’s Red Bull flights; with loops, rolls, and other airplane-like aerobatics, I have no intentions of trying any aggresive 3D with it.

Weight before conversion: 1lb 14oz – 850 grams

After Conversion: 2lb 2oz – 963 grams

Conclusion

Thunder Tiger has made finely detailed scale bodies for their larger helicopters, but this Super Cobra conversion is their first for the Mini Titan. The conversion is a smooth process with the exception of the annoyingly small screws used to join the body halves, and the finished product is very satisfying. Flying a scale heli adds some welcome variety for 3D pilots, and intermediate pilots would appreiciate its stable feel. Beginners would be best advised to master the stock Mini Titan before taking on this conversion. But, fortuanatley the Mini Titan is a great trainer, and would thus provide a good upgrade path and some incentive for when the pilot is ready. Everything involved with building the scale conversion is manageable by the average hobbiest, everything fits well and the plastic parts are high quality. Whether you choose to build it quick and dirty like I did or put a little extra effort into painting the plastic parts, few people would gripe about the looks of the finished product. I would recommend the Thunder Tiger Super Cobra Gunship conversion kit for the Mini Titan E325 to anyone who wants a great looking 450 sized scale heli.

Contact:

Ace Hobby Distributors www.acehobby.com