Public Missiles - Cirrus {Kit}

Public Missiles Cirrus

Public Missiles - Cirrus {Kit}

Contributed by Greg Briden

Manufacturer:

Public Missiles

(Contributed - by Greg Briden - 11/01/02)

Rocket Pic Brief:
Minimum diameter, high altitude rocket.

Construction:
Two main phenolic body tubes, piston ejection, solid resin nose cone.

This was my first HP rocket, which I used for my L1 cert. I do not recommend this rocket for any first time HP builders, and it is a less favorable cert. Let me explain; For one, its hard to find motor retaining rings for a minimum diameter rocket, but I did. The site is now disabled when I try to return to it. Anyway, 4100' expected altitude for a L1 cert is not desirable- the cert team didn't much like it. The instructions were pretty clear, though I freaked out a bit when I saw the 'shock' cord wasn't rubber, but a nylon strap. I called up PML, and they said the kit was changed to add this, (well I'm glad someone told me). The solid resin nose cone is NOT as indestructible as it looks, and doesn't hold paint well. The tip broke off when it fell over and managed to hit a rock. I had to whittle it round with my Swiss army knife. Also, there was no explicit way to attach the nose cone! I didn't want to glue it, for then I wouldn't be able to access the payload section.! In the end I put three screws in. Fiberglass: Oh boy, was this fun. I didn't have much trouble with the actual fins as I did with the cloth. The instructions said try not to get any air bubbles... easier said than done. I launched it on a RMS H73J, and put some sand in the payload section to keep it within our 4000' window. All in all, this was an enjoyable rocket. However, unless, your main goal is to achieve a very high altitude, then steer away from this skybuster.

Finishing:
It came with one decal, sporting the rocket name, but no painting recommendations. I painted the bottom 2/3 blue, and the top 1/3 gold. Sanding plays a BIG part in this type of rocket.

Construction Rating: 4 out of 5

Launch Pic Flight:
The motor mounts I used installed as follows: You drilled three hole into the tubing, then epoxied a grommet that had a hollow threaded center. You then positioned a latch- type hook over the edge of the motor, an put a screw through the other end, into the grommet. One grommet, screw, and hook per hole.

These work out very well if you can find the somewhere, they're also cheap.

You don't need a big motor, unless recording the highest altitude is your goal.

My launch went very well, it came down in the same condition it went up. Although the heavy nose cone spike itself into the ground.

Recovery:
The heavy nose cone spike itself into the ground upon landing. The recovery was took some time, but still, 4000' is a long way. A larger delay would be more preferable.

Flight Rating: 4 out of 5

Summary:
Unless achieving the highest altitude is your goal, steer clear of this well- made skybuster.

Overall Rating: 4 out of 5

Other Reviews

Public Missiles Cirrus By David Fergus
( Contributed - by David W. Fergus) Brief: This is a rocket designed to fly to extreme altitude if desired. It has a 1.6" diameter and is 44" tall with a payload bay and solid resin nose cone. It can be flown with 38mm motors; or 29mm motors with an adapter. Everything that normally comes with a PML phenolic kit is provided including a piston ejection system, parachute, and ...

Flights

Comments:

B.Q.B. (September 25, 2001)

Nice review. I certified Level 1 with a Cirrus Dart this last weekend at the ROC club launch at Lucerne Valley, California. I used an Aerotech H128 and the performance of this kit is really spectacular. I recommend it highly. As far as construction goes, I modified the kit to incorporate secure motor retention. I did this by first notching the aft, root edges of the G10 fins. After the fins were affixed to the airframe using think Cya, I epoxied drywall anchors in the space created between the airframe and fin at the aft, root edge. These drywall anchors are plastic with a metal screw and are roughly triangular in shape. Next, I epoxied some 1/4" basswood triangle stock to the base of the fins to provide some more structure for the fin attachment joint. Lastly, I glassed the fins from tip to tip over the basswood and drywall anchor. Because the drywall anchor in at the base of the fin and inline with the fin, there is no aerodynamic drag with this type of motor retention. Also, I have three metal screws holding the motor in place. After I retrieved my Cirrus Dart from its certification flight, it was obvious that the nose cone/payload assembly slammed back into the main airframe on ejection causing a large crack in the payload airframe. As a result, the nose cone was almost lost on descent. The crack was surprising in that I had glassed the entire airframe including the payload section with 6 Oz. cloth, so it must have taken a helluva knock. Next time, I will replace the stock black elastic shock cord with 10 to 15 feet of 9/16" tubular nylon. I'm fairly certain the relatively short elastic cord caused the midair collision. I was lucky I got all the parts back and the rocket was still flyable! As stated previously, this is a great kit to get started in HPR and incorporates many of the building materials and techniques needed to go on to larger rockets. A 38mm to 29mm motor adapter would be a welcome addition to this kit.

A.D.W. of PML (October 4, 2001)

The reason we provide no motor retention for this kit and recommend friction fitting is that the Cirrus Dart is intended to be a super-high-performance 38mm altitude bird, and any positive motor retention method would add drag to the rocket, reducing altitude. We also mention in the instructions that some people may not wish to mount the launch lugs. Again, this is a drag-producer, and most people with this kit are going for ultimate altitude and use a tower launcher. So, no positive motor retention is by design, not an omission. Friction fitting with masking tape works great, and adds no drag. Regarding no 29/38mm motor adapter, that is available separately as it is for any of our kits that come with a 38mm MMT. To include a 29/38mm adapter with every Cirrus would add cost to the kit for the parts, and many users would not need/want the adapter. So, we keep the kit cost to the minimum and offer the adapter separately. (No offense intended to the reviewer, just wanted to point out why we do what we do with this kit).

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