Wednesday, January 26, 2011

Review: Qmodeling Stiletto

This is one of QModeling's Mega Retro Series (MRS) kits. It's a 1.68:1 upscale of the classic Estes kit and flies on 24mm motors. It is a great looking kit and the parts are of exceptional quality.



Construction:
The kit came nicely packaged with most small components in their own bags (e.g. all motor mount components bagged together). It appears that some of the components have been changed since the previous review was posted. Product improvement is a good thing. The major components per the provided checklist include (apparent changes in bold):

* main body tube, BT-60 white glassine and pre-slotted for main fins
* foil lined BT-50 engine tube
* launch lug/standoff package
* laser cut balsa raceway
* nose cone, conical with a cylindrical base, thick molded plastic
* nose plug, lite-ply
* fin package (all fins are laser cut from 1/4" balsa):

* 3 primary fins
* 3 secondary fins
* 3 thrusters

* instructions, 23 pages of illustrated instructions
* decal set, waterslide
* 6 cardstock body wraps
* engine mount package:

* 4 balsa rings
* 6 balsa panels
* thrust ring
* long motor hook
* rear paper centering ring
* forward centering ring, lite ply

* parachute compartment ring, keeps chute at the forward end of the body tube
* parachute package:

* 18" rip-stop nylon
* 5" x 5" Nomex® protector
* 9' of 200lb Kevlar® string
* screw-eye
* snap swivel

The instructions provided with this kit are excellent. They are detailed, have clear drawings, provide warnings to keep you from messing up, tell you when to do the finishing, and provide 5 views so you can get the decals right.

You can access the full instructions online at the QModeling MRS-Stiletto page. So you don't have to go there mid-read, the following exploded view should show how this kit goes together.
(Image used with permission from QModeling)

My experience with the motor mount was the same as the previous reviewer. All the interlocking pieces fit together nicely and I didn't run into any snags. The mount seems quite sturdy and almost begs for more motor when combined with the thick through the wall fins. I was contemplating modifying the engine hook to allow longer motors such as the Ellis F20, but I decided to build it stock as there are plenty of motor choices at this length.

After the mount is complete, the instructions say to install it in the tube. This requires dry fitting the mount with the fins and tacking it into position. The fins are removed until later in the build. Everything fits well and this process is easy.

Next came the marking for the various components using the included guide. Installing all the outer components were straightforward. The separation rings are built up from two layers of cardstock strips. The quality of the wood in my kit was excellent and required little filling. Elmer's Fill ‘n' Finish was used to do this and was applied before assembly. I found it odd that the instructions didn't say to round the edges of the thick fins. I decided to just take the edge off. With them being so thick and perfectly square, the fins were easy to install.

The nose cone seems nice and sturdy. I found the seams very easy to sand down. It almost seemed like a gel coat material instead of plastic. I found the tip was not perfectly pointy, looking like it chipped off in the mold. I rounded it a bit and it looks fine now. The nose plug didn't fit easily but once in, it is good an snug. The instructions said to trim the end of the cone flush with the plug, but I opted to leave it and add an epoxy fillet.

The recovery system is top-notch, including Kevlar® twine, Nomex® pad, rip-stop nylon chute, and a swivel. The chute is removable and can be transported to other rockets.

Finishing:
The instructions say to prime the model and to paint it gloss white. I used Krylon paint. The nose cone and top of the body tube were then painted copper. It just so happened I had Testor's copper paint from my 58mm JATO. Luck? Fate? I don't know, but the rocket was painted the proper color! As mentioned above, there are plenty of diagrams to position the decals. I personally don't worry about being perfect in this regard but tried to be close. The decals are easy to work with. A couple had a few imperfections, which were fixed with a Sharpie pen.

Flight/Construction:
Prep was easy with the provided chute pad. I didn't have a D12-3 so I went right to the E9-4. The wind was dead calm and the boost was arrow straight. I lost the rocket in the haze and missed where it ejected. I have no doubt that this model could handle an F motor with no problem.

In the earlier review, it appeared the recovery components were oversized. It appears they have now been sized for a better fit. There is also a ring to keep the chute near the top of the rocket. In the calm conditions, the rocket landed nicely about 50' from the pad.

For the second flight, I loaded up an E9-6. It must have ejected fast or hard since the screw eye pulled a plug of wood from the nose cone bulkhead and the chute pulled the hook on the swivel straight. One fin also broke as the body was in free-fall.

Lime Stiletto
When you rebuild a rocket, you can try to restore it back to the original design, you can remodel with conventional parts, or you can go odd-roc on it. I had this plastic lime juice bottle that was looking for a home, and didn't feel like ordering a 'real' nose cone, so...

The base of the bottle was pretty close to the diameter of the BT and I happened to have a piece of junk tube that was the same diameter as the Stiletto. It was too flimsy and of too poor a quality to use as a stand alone rocket body, but was perfect for this application. I cut off the bottom of the bottle and slid the tube in until it touched the inside of the neck. I also have a bunch of thick, short tubes that can be sectioned lengthwise to make couplers and one of these became the shoulder of the new nose. I made a bulkhead from scrap 1/4" balsa and epoxied some elastic to the side of the shoulder. After the first flight, I should have added a few feet of elastic. This probably would have saved the Stiletto's nose and 'chute and eliminated a few minor zippers to boot.

The CP/CG relationship is still about the same, so the Lime-Stiletto is ready to go. I'm still thinking of a better name, but for now, that will do. Nose cones are the easiest mods. If I change my mind, I can always buy a real cone.

Flight/Recovery
I have flown this configuration four times on E9-6's.  Ejection was a tad late in each case but recovery has been successful.