S7 – Scale
S7 is the most challenging of the spacemodeling events held on the international level. Not only must the models be precise replicas with enormous amounts of detail and flawless workmanship, but they also must be mechanically complex enough to perform many “special effects” during flight in order to score high flight points. Special effects points are awarded for dropping boosters, heat shield separation, payload fairing jettison, deploying a payload, radio control, or similar operations performed by the original vehicle. Bonus flight points are also awarded for staging and clustering, as well as for multiple parachute deployment. To implement these capabilities in a model and still maintain scale quality requires a great deal of planning, testing, and ingenuity. The maximum flight score is 300 points, out of 900 points possible for the event. It is not uncommon for the top few places after static judging to be separated by only a few points. The competition is only half over after static judging, and the top places can change dramatically between static and flight judging.
While it is paramount to have a full flight profile that performs according to plan, it is the static score that provides the bulk of the total points awarded. The importance of a good static score cannot be overlooked. In fact, a static score can win or lose a place for a model that does not have all the bells and whistles of the more complicated models.
What does it take to earn a high static score? A model that is accurate, exhibits quality workmanship, and is highly detailed. The level of detail on the top models must really be seen to be appreciated; photographs usually do not begin to capture the surface detail that is added to the top models – rivaling the detail on a good plastic model airplane kit.
Static judging points are awarded as follows:
- Adherence to Scale = 200 points (160 points for dimensions, 40 points for colors and markings)
- Workmanship = 250 points
- Degree of Difficulty = 150 points (110 points for degree of difficulty, and up to 40 points for model uniqueness)
- Flight = 300 points
A data package is required to document the model, even though no points are directly awarded for the quality of the data package. Only details and features (rivets, doors, etc.) that are documented in the data package will be awarded points under Adherence to Scale, Workmanship, and Degree of Difficulty.
The data package MUST include stability (CG/CP) and flight performance calculations for the model. The omission of the stability and performance calculations may result in a DQ. The data package must also include a “workmanship drawing” that documents the dimensions of the prototype and the ideal dimensions of the model. The workmanship drawing may be of any convenient size (i.e., it does not need to be 1:1 with the size of the model).
Dimensional score is determined by the accuracy of the following six items:
- Overall model length
- Nose cone length
- Greatest measurable diameter
- Length of first stage
- Fin span (individual fin, or tip-to-tip)
- Selected dimension greater than 10 mm (second stage length, diameter, etc.)
Each dimension has a maximum score of 25 points. The score reduces 2 points for every 1% error.
The contestant’s FAI number must be on the exterior of each stage of the model. The lettering must be 4 mm tall or greater. Unlike NAR scale model competitions, no points are subtracted for neatly-done contestant numbers interfering with the scale appearance of the model. Similarly, launch lugs on FAI models do not detract from the static score.
The list of highly competitive prototypes for the S7 Scale event has traditionally been fairly limited. The Saturn 1B is a popular prototype. The Apollo 7 Saturn 1B drawing by George Gassaway is a great example of the “workshop drawing” that must be included in each scale documentation packet. Other popular prototypes include Ariane 3 and 4, and the Soyuz. The Soyuz by Alexandr Levikh of Russia (pictured above in flight) has won S7 at many world championships. It has multiple operable stages and about 20 different component parts (stages, booster strap ons, etc.) that separate with their own recovery systems. The Saturn V has also been popular in recent years.
The Space Shuttle or Energia/Buran would appear to be great candidates for this event. However, they have yet to be proven in competition. They are very difficult models to fly in a manner consistent with the prototypes.
Many other prototypes — Nike Hercules, Little Joe I and II, Long March 3B, and more — have been entered at world championships. However, these models generally do not do well. They may be perceived by FAI judges to have a lower degree of difficulty compared to a Soyuz, Ariane, or Saturn.
To encourage more diversity, the 2013 FAI Code introduced 40 points for “originality”. A model will receive 40 points if it is a unique prototype, 20 points of two models of the prototype are entered, and zero points of three or more of the prototype are entered.
The basic strategy for S7 is quite simple: build an exquisitely detailed scale model that is within 1% accurate in all the required dimensions, is flawlessly finished, and executes a flight profile with as many effects as possible. Simple strategy, but extremely challenging to execute!
Within the basic strategy, here are some points to consider:
Prototype Selection. The first step is to select a prototype to build. Be sure to pick a prototype that you enjoy, that will score well, and is within your modeling abilities. It is a good exercise to estimate static and flight scores for candidate prototypes to help with your selection decision. Annex 1 (“Space Models Judges’ Guide”) in the FAI Code contains a detailed breakdown of the judging algorithm and points allocation. Going through the judging steps can provide a pretty good estimate of how candidate prototypes will score, as well as for the specifics of how many points can come from time spent on various aspects of the model’s construction.
Pick a prototype that offers sufficient avenues for special effects. An Ariane 3 can have an advantage over a Saturn V in that it can drop its boosters in flight. An Ariane 4 is even better. Don’t forget to consider future growth of your flight profile. Start out simple and “complexify” as you gain experience.
Once you select a prototype, stick with it! Only by building successively refined models of a prototype can you hope to attain the detailed data, construction jigs, and techniques to build a first-class model.
Model Accuracy. Make sure that your model is accurate in the required dimensions to within 1%. Don’t spend needless time getting the tiniest detail dimensionally accurate, as they won’t be measured. As long as details look about right, dimension-wise, that is sufficient.
At the contest, do not be afraid to check the judges measurements of your model – mistakes are made.
Details. Add any details that you can handle and have even the weakest documentation for. In general, judges seem to favor lots and lots of details. Include small details somewhat oversized if needed rather than leaving them out. Judges seem to like to see lots of detail, even if it is somewhat oversized to make it visible and build-able. Make sure that all details are neat and well done. Many (most?) judges do not look favorably on poor-quality workmanship, even if that is how the prototype looks. For example, a “neat” V2 model will probably get a higher score than a model that includes more realistic buckled panels, unless meticulously documented.
Painting. Painting is by far the quickest way to ruin an otherwise great model. Practice painting on scrap pieces before you even think of pointing your airbrush at your model. The type of paint to use is an individual choice. Acrylics are good because they resist yellowing. The Testor’s Model Master “Acryl” line seems to be a good formulation. Like most acrylics, the first few coats should be dusted on or beading will occur. Tamiya acrylics are another excellent choice. Enamels (such as Testor’s Model Master enamels) are OK but can take a long time to fully dry. Again, practice beforehand, and make sure there are no incompatibilities with undercoats or overcoats.
Boilerplates. Well before the WSMC, get plenty of flight experience by flying a boilerplate model. The boilerplate should be the same size and scale as the final scale model. It is very important to add ballast to the boilerplate model to make sure that it represents the weight of the final scale model. This will help verify flight characteristics including any special effects such as clustering, staging, jettisoned components, and recovery systems.
Develop a checklist that lists every step required to prep and fly the model. The checklist will be very helpful when flying under high pressure conditions of the WSMC.
Schedule. Early on, develop a schedule for construction and flight testing. Don’t procrastinate and wind up building at the last moment. (This is SO much easier said than done!)
Flight points can account for up to 300 of the maximum 900 points for S7. Only 60 of the 300 points are for the basic flight (nice liftoff? stable? weathercocking?). The remaining 240 points are awarded for staging, clusters, special effects, and recovery. The flight can also lose points for launch misfires and cluster misfires. The complete list of flight points is provided in Annex 1 of the FAI Code.
The highest points or unusual issues are discussed below.
- Special Effects (0-60). Separating boosters, radio control devices, prelaunch smoke/motor, ejecting satellites, deploying shield, scale launcher, gliding recovery, or other special effect. Special effects may only emulate the actions of the prototype. Maximum of 15 points per effect. Simple effects (like prelaunch smoke) will not be scored as highly as complex effects (SRM jettison, etc.).
- Staging (0-60). Add 30 points for each successful stage separation. No points for a single stage model.
- Clusters (0-30). Add 5 points for each engine that ignites up to maximum. No points for single engine models.
- Staging and Cluster Misfires. Subtract 15 points for each engine that fails to ignite. (0 or minus)
- RC Gliding Descent (0-50). If the actual prototype has a gliding portion (Space Shuttle, Buran, X-37, etc.), you can get up to 50 points for “stable gliding, realism of gliding descent of the prototype, and safe landing without damage.”
- Recovery – 1st Stage (0-20). You get 10 points per deployed parachute. This applies to a single stage model or the first stage of a multistage model.
- Recovery – Upper Stage(s) (0-20). You get points for each parachute (10 points each) and streamer (5 points each).
- You can get a maximum of 30 points for clustering. You won’t get more flight points for clusters with more than six motors. However, 15 points are subtracted for any cluster motor that fails to ignite. Therefore, clusters with more than six motors (Saturn IB, Little Joe II, etc.) should be used with caution.
- Cluster points are awarded only for motors that are installed at the correct locations on the prototype. Any motors placed adjacent to nozzles — rather than at the nozzle location — will not be awarded cluster points.
- If your model uses a cluster, you must present your model to the scale judges after flight to show that all of the motors ignited. One other post-flight item might be a demonstration/verification of in-flight on-board special effects (altimeter, cameras, etc). However, the issue of post-flight inspection of in-flight on-board special effects has not yet been demonstrated at a WSMC.
- An important difference for FAI S7 rules compared to NAR rules is that there is no deduction for flight damage under FAI rules. This may influence how some parts of your model are constructed – or at least provide some relief if your flight doesn’t go perfectly.
At the WSMC, enlist the help of a “prep buddy” to assist you in getting the model ready to fly. There are many steps to getting a competitive S7 model ready for flight, and a helping hand is extremely useful. The “prep buddy” can also help make sure you don’t miss a step or do something stupid. Be sure to follow the checklist that you developed when flying the boilerplate model.
Do as much flight prepping as you possibly can the night before. It is a good idea to have your model transport box set up so that you can have all the motors loaded in the model before you get out to the field. During S7, flying the time will disappear very quickly.
Always “go for broke” during the flight. Do not hold back some effects on the first flight with the idea of simply getting a qualified flight, then going all out on the second flight. There is a real danger of running out of time for the second flight.
A somewhat overlooked challenge is that scale models can be very difficult to transport on an airline half way around the world. Take time to plan and design a safe means to transport your model. Ideally, having the model transported in carry-on baggage would be safest approach. However, that probably isn’t feasible for larger scale models.
Pack your model to survive the rigors of airline baggage handling and access/inspection by TSA agents. Pelican-style cases (often used for shipping electronic equipment) are very rugged. If feasible, select cases that do not incur oversized baggage charges (check with the airlines to confirm allowable sizes). Cases with wheels are especially handy. Try to avoid using hand-made wood crates or cardboard boxes for checked luggage. Airlines are very reluctant to accept items that aren’t standard luggage due to liability issues.
Remember that you will need to transport your own ground support equipment. This is critical if your model uses a long launch rod or rail, or if you’re bringing a launch controller tailored for cluster ignition.
A good exercise is to perform a “practice run” with your boilerplate model while participating in a team practice launch. This will demonstrate if your model and equipment will pack and transport well or if there are any special issues that arise.
A GREAT ADVENTURE
A final thought: this is the ultimate event for people who truly love scale model rockets. Although the WSMC S7 event is a competition, in many ways it’s more like a convention, a gathering of the finest spacemodelers in the world. These master modelers build to the very best of their amazing capabilities and then gather for one week every two years to show and fly their models for the most knowledgeable and appreciative audience in the world. You don’t have to win a medal to win at this event. Representing your country, placing your model on the judging table next to the finest models in the world is an incredible honor. Flying your model for a crowd of people who truly understand the effort, commitment, and love of the hobby it takes to do this is an incredible thrill. If you truly love building scale model rockets, this is the event for you.
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