Madcow Rocketry - Screech {Kit}

Contributed by David Reese

Construction Rating: starstarstarstarstar
Flight Rating: starstarstarstarstar_border
Overall Rating: starstarstarstarstar_border
Diameter: 1.50 inches
Length: 40.50 inches
Manufacturer: Madcow Rocketry
Madcow Rocketry Screech

Brief:
Single-stage minimum diameter 38mm model with parachute recovery.

Construction:
My early production kit included two body tubes, three lite-ply fins, a coupler/baffle/eyebolt assembly, full recovery system with Nomex® protector and Kevlar® shock cord leader, 1/4" launch lugs, and a beautiful balsa nose cone. All parts were clearly of high quality with precise fit and a clean finish out of the bag. If so desired, this kit could be constructed in fifteen minutes or so--just enough time for the epoxy to dry on the three fins.

The high quality parts scored major points with me coming out of the bag. Madcow clearly takes care in the preparation of their kits. The small-format instructions were well written and clear, albeit intended for a modeler with a few kits under their belt. This level of instruction was appropriate, considering the abilities of the finished product.

The lite-ply fins were easy to bevel to a nice taper on the leading and trailing edges; this material is perfect for rockets of this size and form factor. For flights achieving 0.85 Mach or greater, fiberglass reinforcement is recommended for the fin can. I opted for a single layer of 6oz carbon fiber with peel ply, as I intended this to be a fast rocket.

Madcow Rocketry Screech The vehicle is designed to break at the nose for recovery, with the shock cord permanently mounted at the tube coupler via a lite-ply baffle plate and eyebolt. This arrangement typically bothers me for two reasons: one, it leaves the shock cord attachment point inaccessible in case of burn-through, and two, ejecting from the nose with a long rocket underneath adds unneeded stress to the airframe. Madcow mitigated these concerns by including a heavy-duty Kevlar® leader to be attached to the shock cord mount and keeping the rest of the vehicle light enough that zippering or crimping shouldn't be a problem.

Nonetheless, I elected to build my rocket using Stu Barrett's "Anti-Zipper" configuration with separation occurring at the coupler/baffle assembly and the nose affixed to the upper section with three #4 wood screws. I like this flexible layout as it also allows me to mount an altimeter bay underneath the nose cone for altitude recording, if so desired.

I typically replace paper launch lugs with brass lugs, as the brass is dimensionally stable, providing a freer fit on launch rods, and also presents less frontal area, lowering the drag coefficient of the vehicle. (I prefer lugs on small minimum diameter vehicles.) However, the lugs included with this kit were absolutely wonderful--thin, lightweight paper sized slightly large to ensure a loose fit over the rod. I used the stock lugs on my kit and have not regretted that decision at all.

My model was from an early production run, and thus did not include a 29mm motor mount kit. To adapt to 29mm motors, I purchased a LOC MMA-2 and epoxied three #2-56 nuts inside of the adapter during assembly. These nuts line up with three 5/64" holes directly aft of the fins, allowing me to secure a 29mm motor in the vehicle by first securing it in the motor adapter, and then bolting the adapter into the base of the rocket. With a permanent 29mm motor mount, this kit would remind me of a modernized version of the LOC Legacy.

Madcow Rocketry ScreechMadcow Rocketry Screech

Finishing:
Finishing was a breeze. The tube spirals were light and with a few coats of primer needed no filling. The nose cone was soaked in several layers of thin CA to harden it and sanded smooth. I used Krylon red on the upper sections of the rocket and painted the fin can with appliance epoxy black. The vehicle includes no decals, which is typical for mid- to high-power rockets, but may be a letdown to those stepping up from smaller models. The completed rocket looks great, and is very unique on the range. The short nose cone, long body, and sharp fins combine into a very eye-catching design.

Construction Rating: 5 out of 5

Flight:
Madcow gives no guidance on motor selection, relying instead on the modeler's skill in picking proper propulsion. Again, this decision seems on par with the skill level required to fly this rocket. My finished vehicle came in at 12.1oz. It's a little heavy for a D12, but definitely workable on most 24mm Aerotech motors, and a real winner for most 29mm and 38mm selections. I opted to fly an F40W for my first flight with a 10 second delay drilled to somewhere between a -8 and a -9.

The only downside to minimum diameter rockets is the challenge they present for motor retention. Tape fit has been reliable for me in the past, but it is certainly not my method of choice. For retaining 29mm motors, I use the aforementioned adapter. It is short enough that motors protrude from the forward end of the adapter, allowing a tape stop to be built up and prevent the motor from ejecting. For 38mm motors, a variety of options exist. The fins on Screech are mounted far enough from the aft end to allow inclusion of a commercial bond-on motor retainer. Alternatively, an internal device such as all-thread, a Kevlar® line, or a 1.5" "Cherne Gripper" attached to the forward closure could be used to maintain the sleek lines of the vehicle. Madcow only points to the friction fit method in the instructions. A few more ideas would be nice but certainly not expected.

The recovery system packed well, and I backed up the Nomex® protector with extra wadding. I coated the inside of the body tube and the outside of the coupler with thin CA and sanded to provide a smooth, dimensionally-stable fit that was easy to adjust using masking tape.

Flight on the F40 was excellent. It picked up the model nicely and sent it rail straight into the sky to a projected altitude of 2300 feet.

Madcow Rocketry ScreechMadcow Rocketry Screech

Recovery:
Deployment was slightly past apogee, but the anti-zipper design worked its magic and deployment was smooth and successful. Descent on the included bright orange nylon parachute was quick but acceptable, and the rocket recovered close by. Post-flight inspection revealed no damage whatsoever. The chute protector showed no signs of ejection residue. The brunt of the burning particles were absorbed by the half-moon baffle disc/shock cord attachment point. For future flights, I will probably include wadding beneath the baffle to protect this part of the vehicle as well.

Flight Rating: 4 out of 5

Summary:
This is a simple kit that delivers on what it promises. I was pleasantly surprised by the kit's completeness. The full recovery system and well thought out component selection made construction a breeze. I made a few modifications to suit my tastes and my flying style, but this kit could easily be constructed by someone new to the genre of mid-power without issue. The only drawbacks are (potentially) a lack of decals and difficult motor retention, however, those issues come with the territory of minimum diameter and mid to high-power kits so they do not detract significantly from the vehicle. And for the price, this kit really can't be beat. Screech was my first Madcow kit. It definitely won't be my last.

Overall Rating: 4 out of 5

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