U.S. Rockets Fire and Forget

U.S. Rockets - Fire and Forget {Kit}

Contributed by Frank G. Whitby

Construction Rating: starstar_borderstar_borderstar_borderstar_border
Flight Rating: starstarstarstarstar_border
Overall Rating: starstarstar_borderstar_borderstar_border
Manufacturer: U.S. Rockets
US Rockets Fire and Forget

Brief:
The USR Fire and Forget is a small 29mm minimum diameter rocket. It is a 3FNC style rocket with trapezoidal fins. I like this styling in general and I think that this makes for and attractive rocket. It should be able to fly on anything from C to G power and USR suggests flying it on a couple of H motors as well. The rocket is very stout, considering the light weight and small size. USR calls this their "reference rocket". I have no idea what this means, but I assume that they must use this as a sounding rocket to test wind and rain conditions prior to launching any other rocket and that the altitude achieved by any other flight is normalized to that achieved by Fire and Forget. The proclamation of Fire and Forget as the reference rocket of USR seems a bit strange to me since they provide no explanation of the matter.

Construction:
The kit came with one triple-folded sheet of adequate but limited instructions, printed front and back of the paper. The instructions provide useful diagrams and details on construction and flying, along with a parts list. I discovered the kit was missing one part--1 shock cord (SC-5). The rocket uses a balsa nosecone that fit well, 3 nicely cut trapezoidal plywood fins that appeared to be of good quality, and all other components appeared to be in good shape. Despite the missing shock cord, I decided to proceed with building. I elected not to contact USR to discuss these failings.

I built the rocket as per instructions except for using 5-minute epoxy throughout construction. I tapered the fin edges as described and used my Estes fin alignment guide for fin installation. This is a minimal diameter rocket and the instructions suggested surface mounted fins. I think that this should be fine. After tacking the fins in place with epoxy, I gave them a nice fillet. I cut the ¼" launch lug on an angle as suggested and gave the lugs a fillet as well.

The recovery system calls for a ¼" elastic shock cord to be glued into the main body tube using the 3-fold paper method. I installed it as described, using 6 feet of ¼" elastic shock cord that I had lying around.

At this point I ran into what I view as a major failing of the kit. USR describes two possible methods of construction, neither of which I think are appropriate, given the parts needed and the possibility of limiting the usefulness of the rocket depending upon the path taken. Here are the 2 different build techniques in the instructions:

  1. The instructions suggest building the upper half of the rocket by first gluing the shock cord, via the tube coupler, into the upper body tube. The coupler must be friction fit into the lower body tube. Then the instructions say to also friction fit the nosecone into the upper section. This has two problems, as I see it. First, friction fitting BOTH components makes proper separation unsure--the ejection charge will cause separation of either the upper body tube from the lower tube, which is by design, or separate the nosecone from the upper body tube, which would result in a lost nose cone and possibly failed recovery deployment. If the rocket is built in this way, the nosecone really needs to be glued in place if one wants to keep from losing it. Second, this building scheme limits the usefulness of the upper section, as it cannot be used as a proper payload section.
  2. The alternate method of construction is where the two body tube sections are glued together and separation is designed to occur at the nosecone. The justification for constructing in this way is that it allows one to use a very long motor. Although this makes more sense by restricting separation to a single point, this method again eliminates the possibility of payload and assumes that you want to use an enormous motor in this small rocket.

I chose to build the rocket in a third configuration which preserves the upper section for payload and insures separation at a single point. I proceeded to make my own payload plate, attach a screw eye, and glue it into the upper section along with the tube coupler. This produces a nice payload section similar to that of the USR Miniroc 1.2 with a friction fitted nosecone. Separation now occurs between the body sections only. This method prevents you from using the largest possible motor, which I never intend to do anyway.

PROs: The kit parts are stout. Construction is straight forward and should be suitable for a beginner if it weren't for some of the failings of the kit.

CONs: The kit had 1 missing part that cost me a buck to replace. The instructions are cobbled together from those of other kits and could be edited better. The discussion of 2 alternate methods of construction omitted what I believe to be a superior third choice that would provide most people with the most versatile rocket in the end. The instructions do not include an adequate discussion of the pitfalls of construction method number one, where the rocket might separate at either of two points.

Finishing:
I did not fill the grain of the balsa nose cone. I think I would use a plastic nose come if I were designing this kit as the balsa nose cone does not seem to be made of very nice balsa and will always be prone to dings. The body tubes were very smooth so I did not consider filling spirals. I sprayed the rocket with a single, thin coat of automotive primer, gave it a brief sanding, then added a single coat of "hammered gray" automotive spray paint. I then used masking tape to add stripes with single coats of red and blue "hammered-look" paint.

The finished rocket weighed 115 grams. I perhaps added a few grams by substituting 5-minute epoxy instead of the recommended yellow wood glue for construction. The final weight listed on the kit pack is 90 grams and the USR web page lists final weight at 40 grams. I cannot explain this discrepancy, but I find the 40 gram projected weight to be impossible. This rocket is similar to Miniroc 1.2, but is slightly longer and with different shaped fins, so I expected it to weigh a little more than Miniroc 1.2. I used my alternate construction method which added a payload plate and screw eye to the parts list, adding 9 grams to the final weight. I might note that I used a much lighter screw eye than the one (part SE-0) that came with Miniroc 1.2. I feel that if I had been extremely conservative in my use of glue and paint, I might have been able to finish this rocket at 90 grams. I think that a better value can be found in kits from other manufacturers.

PROs: Painting was a snap. I chose not to follow USR recommended color scheme which is hard to visualize given that USR shows only black and white drawings and/or photos of their rockets on their website and the instructions only include line drawings of the rockets. I typically do not adhere to manufacturer’s recommended schemes anyway.

CONs: I chose not to apply the USR decals that came with the kit. I liked only one of the decals with the USR logo but I had already done some fin striping so the logo would probably not look good anyway. The final weight of the rocket as described by USR is inconsistent between kit and web catalog.

Construction Rating: 1 out of 5

Flight:
I flew Fire and Forget on a D12-7. I prepped for flight as per USR instructions (masking tape motor retention should be good) and used a 24mm motor adapter. I used crumbled cellulose insulation as wadding and packed a small nylon chute (12 grams) in place of the streamer (11 grams). One wrap of masking tape provided a good fit of the payload section coupler to the lower body tube. I added 2 wraps of masking tape to the nosecone shoulder to give a very tight fit as I did not want to glue it in and I did not want to lose the nosecone. The payload section was flown empty despite the possibility of hungry desert aliens intercepting the rocket in flight.

The boost was to quite a nice altitude. Ejection was at apogee. The motor was kicked out. The chute gave good recovery and the rocket remained aloft for several minutes. There was only a gentle breeze so recovery was only 100 yards away. Upon inspection, the rocket suffered no damage except that the shock cord clearly needs to be replaced before flying again.

Recovery:
The shock cord system clearly wants for some sort of a Kevlar® leader cord. The 3-fold paper glue-in method should still work fine though. I used 6 feet of shock cord but this is probably the minimum required in order to avoid body tube dings.

Flight Rating: 4 out of 5

Summary:
The Fire and Forget flies nicely and is built of rugged stock. Despite this, I gave the rocket a low rating because of the missing parts that typified my experience with USR. The overall shoddy nature of the kit components and instructions I think represents this kit as a poor value.

Overall Rating: 2 out of 5

Other Reviews
  • U.S. Rockets Fire and Forget By Nick Esselman

    (10/01/04) U.S. Rockets states that the " Fire & Forget is the reference model rocket for U.S. Rockets. It is a near minimal diameter rocket in 24mm mode and a minimal diameter rocket in 29mm mode. The maximum 29mm motor length is 9" (H120-12). Aerospace specification airframe tubing is used to assure high performance and high strength. " What caught my attention was " reference model ". ...

Flights

Comments:

avatar
J.I. (October 8, 2004)
1. You failed to follow instruction step #1. Sand the fins to an airfoil taper. That reduces vehicle drag 15% and improves appearance a lot and obviates the need for "clean cuts" on fins. 2. I agree it is not "typical" of USR kits since most are dual deployment capable.

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