S5 – Scale Altitude
- Flying scale model of a real rocket to the highest measured altitude
- Juniors fly S5B (A motors in each stage), Seniors fly S5C (staged B motors)
- Score is the sum of static judging score (max 600 point) and altitude (in meters)
- Altitude is measured using an electronic altimeter
- S5B dimension requirements: min length = 500 mm, min diameter = 40 mm for at least 20% of rocket length
- S5C dimension requirements: min length = 650 mm, min diameter = 50 mm for at least 20% of rocket length
- Three flight rounds, with altitude score based on best altitude of the three rounds
S5 (Scale Altitude) is a challenging event that combines the points achieved for static craftsmanship on a scale model with the altitude achieved by the model in flight. Static judging is the same as S7 (see S7 rules). Top static scores are usually in the 300 to 400 range. The altitude achieved in meters is added to the static points to determine the overall score. The objective is to gain as many points possible between craftsmanship and altitude. This can be a trade-off.
The judging rules for S7 have changed in the 2013 edition of the FAI Code (see the S7 page for additional details). The effect for S5 is that the maximum number of static points has decreased to 600. Of those 600, 40 points are allocated for prototype uniqueness, and 40 points are allocated for accuracy of the third stage. Since it is very unlikely that competitive S5 models will be unique or have a third stage, the maximum number of static points for S5 has likely been reduced to 520. This makes the altitude portion of the S5 score even more important than before.
There has been some discussion about defining a minimum diameter for upper stage, which would likely eliminate the current advantage of the Bumper WAC. However, no changes will be made until after the 2014 World Spacemodeling Championships.
S5 models must be representative of an actual flying rocket. To achieve competitive scores while satisfying the dimension requirements, the model must be flown as a two stage model with a large booster and a small upper stage. Therefore, the selected prototypes are high altitude sounding rockets.
S5 has evolved to where prototypes fall into three groups: 1) Nike-Apache (or similar Nike sounding rocket); 2) Taurus Tomahawk; and 3) Bumper WAC. Generally, the Taurus Tomahawk gets the highest static score, followed by the Nike Apache and Bumper WAC. However, the upper stage of the Bumper WAC will be very small and light, so the Bumper WAC will achieve by far the highest altitude. After summing the static score and altitude, the Bumper WAC is the superior entry. However, the small WAC upper stage is very difficult to see during ascent and descent. Recovering the upper stage is a major challenge, even with a large recovery team.
An assessment of recent S5 candidates and performance is attached.
If you’re going to spend months crafting a competitive S5 model, remember that, once you ignite the motor, it’s just an altitude model! Don’t begin by building a scale model without thinking through your flight strategy. Build numerous “boilerplate” models, and test fly all aspects of your flight, most importantly staging and recovery techniques. If they should fail, you will be DQ’d, and that is an awful feeling after having traveled half way around the world. Test flying and data acquisition could occupy most of your modeling time, but can also be the most fun and rewarding.
Select a competitive prototype that can be easily documented for scale. Obscure rockets like the UTE-Tomahawk might be very efficient and adhere closely to established minimum size constraints, but documentation and color photographs may prove extremely difficult to locate. Have the minimum data on a number of prototypes and possibly locate a bit more before selecting the one you wish to model.
These “scale” models cannot be built “heavily” to survive numerous flights and still be competitive. Most winning S5 models are altitude models in disguise, they merely appear to be a scale model on the outside.
Begin by designing an altitude model and figure out how to add the detail to it. But, “lightest” is not necessarily better, either. There will be an “optimum” weight for each stage and configuration and that can best be determined using commonly available altitude prediction programs for your PC or Mac. Many European modelers have sacrificed scale detailing to increase altitude potential. By omitting projections on the surface of the sustainer to reduce drag, much higher altitudes can be achieved. With proper considerations this can sometimes be an even more than reasonable trade for the loss in static points. There is a saying at the WSMC that “he who places first in S5 static, never wins.” Many times models ranked in the middle third of the static scores will actually win the contest by posting superb altitudes. Your static score should be reasonably good or better, but to win consistently takes a very good “altitude” potential.
If possible, models should be built to be flown as both single and multiple staged. If weather conditions are poor, it may be necessary to make a low altitude flight to avoid flying into clouds, making it nearly impossible to recover the sustainer stage. Practice flying even in bad weather conditions, and expect to loose a number of your boilerplates. Remember, it’s OK to ruin boilerplate models; the knowledge gained could save you from disaster in a competition that is held only once every two years.
Use a piston launcher (with a tower) to make the most of your booster motor power. Weather and tip-off are factors to consider if you have a heavy booster like the Bumper WAC. You may wish to have different combinations of motor impulse and delays available, each suitable for different conditions.
|2012 WSMC S5 Review 100513||May 28, 2014, 3:14 am||376 KB|