Saturday, December 18, 2010

Review: Odd'l Rockets Wedgie

The Odd'l Rockets Wedgie is a tetrahedron (3-sided pyramid) that flies on 18mm motors and recovers via a rear-eject streamer. I want to thank Chris for letting me test out this cool oddroc kit. Mine is s/n #2!

The Wedgie comes professionally packaged in a plastic bag with the cover of the instructions visible. The small parts were separately bagged. The body is formed from 6 pieces of laser-cut balsa. Its motor mount includes a two-part motor tube, two laser cut centering-triangles, a motor block, a cardboard plug, and two 'standard' centering rings (BT-20 to BT-50 sized). Recovery parts include an elastic shock cord, swivel, and crepe streamer. Miscellaneous parts include a 1/8" launch lug and clay nose weight.

The instructions are detailed and well illustrated. Don't let its 'odd' nature fool you. This is a builders kit and I recommend you actually read the instructions thoroughly before beginning. It is rated as skill level 3, and I concur with this rating.

You start by building the two-part motor mount. The upper part will eventually be attached to the body while the lower section is free to eject and deploy the streamer. Construction is straightforward and all the parts fit perfectly. The key points for the mount are making sure the centering-triangles are installed perpendicular to the motor tube(s) and at the prescribed locations. An attached photo shows the mount being constructed with fillets drying.

The body assembly is a bit more difficult. Here, you begin by gluing the 2 halves of each of the three faces together. It appears this was to alternate the grain directions and add strength. Next you sand the joint flat. Easy so far.

Now for the hard(er) part - beveling the edges to allow them to fit well. A sanding guide is provided, but this step strained my clumsy building skills. I cracked one as I was sanding and would recommend doing the beveling before joining the pieces. Easily fixed.

The faces are supposed to be joined with CA. Instead, I used Titebond molding and trim glue. This is thick and tacky and let me put the three pieces together rather easily. I taped the corners and top while the glue set. Later, I reinforced the joints with thin CA. There is a template to locate and cut the hole for the launch rod. If I were to do it again, I'd also cut this before the faces are joined.

Next, you install the clay nose weight and install the upper motor mount. You have to make sure the clay doesn't interfere with the launch rod. I also had to extend the opening a tad further down the body so the launch rod would clear.

The shock cord is attached to the inside base with a strip of balsa that is provided. (see photo) You are instructed to notch the middle so the elastic cord will fit under it. This was challenging since the strip is only about 1/16" thick to start.

Odd'l provides several skins that you can download, including a blank one. I finally decided on 'The Point', which is themed like the classic cone rocket kit of the same name. I printed three copies of the template and sealed them with a clear coat before starting. The instructions say to use spray glue. I dread using the stuff, but it is about the only choice for plain paper like this. I was pleasantly surprised that the skins stayed on the rocket and not the builder.

Overall, this was a fun and slightly challenging build. I'm happy that Chris's parts were so precise. Everything fit as advertised and the skins are nice. I'd suggest tweaking the steps to bevel-before-joining and to cut the launch rod hole before assembling the body.

Prep is conceptually simple - fold and pack streamer, install motor by taping it to the lower motor tube, install igniter, and launch. I found that packing the streamer and getting the motor to stay in place took a tad of fiddling. My main concern prior to launch was the shock cord attachment. Will it hold? Will the exposed elastic get burned by hot gasses trapped in the base?

Well I flew the Wedgie twice. I used Quest Q2G2 igniters, which are nice because the long leads make it easier to connect the clips.

It was quite windy for the flight on a Quest 'long burn' C6-3. It weather cocked a lot but still attained a nice altitude. Ejection occurred as planned and it recovered well. The only damage, if you will, was the tip of one of the skins peeled back as it poked into the sod. This was easily fixed with some cellophane tape. In fact, I recommend you add some preemptively.

I flew it again on a Quest B6-4. The winds had died down a bit and the boost was a lot straighter. Recovery was a bit late but was still in plenty of time. This time, the crepe streamer was singed a bit. It turns out that I didn't use a square of wadding as directed in the instructions (it's even underlined for emphasis). D'OH. I guess that's what happens when you read, build, put on shelf for a couple of weeks, and then rush to the launch.

The third flight was on another Quest C6-3.  This time, the Wedgie went unstable!  The winds were lighter than the prior QC6 flight so I was surprised. However, we suspect this is due to the lower thrust on the Quest "long burn" motor.  Odd'l is now recommending that only Estes C6's (see comments below).

I love oddrocs and I like the way this one flies. Its prep is easier than a 3/4FNC in some ways (no wadding) and harder in others (more dexterity required). The only down side I see is that the streamer may need to be replaced after several flights (or maybe not if you follow directions).

06/10 - "I agree after it was attached, it seems plenty sturdy. If I had known it was limewood I might have used it to stir my rum and coke instead! (P.S., Typos on the review have been fixed.)" (D.S.)

06/10 - "Quote: "The shock cord is attached to the inside base with a strip of balsa that is provided." The shock cord attachment strip is actually Limewood. While it looks like balsa, it is much stronger. After dozens of Wedgie flights, I have yet to have the Limewood strip pull off or fail." (C.M.)

06/10 - "You're welcome and thanks again for the opportunity to build and fly it! I actually don't think the Quest C6-3 is that bad. It is very common for saucers, cones, etc. to weathercock a bit and it was very windy for the first flight!. It is not like it was a scary flight or too low an ejection. However, it may be safer to at least be on record about the issue. " (D.S.)

06/10 - "Thanks for the great review Dick! As with most Odd-Rocs, it is best to fly them in calm or low wind conditions. We do recommend flying the Wedgie with the Estes C6-3 engines. We don't recommend the Quest C6-3 in the Wedgie. The Quest C6-3 is a longer burning, lower sustained thrust engine. The Quest C6-3 has its place but not in a higher drag Odd-Roc like the Wedgie. In regards to the streamer singe, the instructions do say to drape a square of wadding over the rolled streamer." (C.M.)