ROG Ramble
The information below is subject to change as
more event tips and details are included. Please monitor this page
regularly.
Faculty coordinator: Dr. Andrew Tomasch [atomasch@umich.edu].
Event Description:
Teams of two students construct two simple rubber-powered model airplanes from inexpensive commercial kits. Points
toward the team's final score are awarded for a quiz and for flight performance. One point is awarded for each second that a
model is in the air and the sum of the two longest flights achieved, in seconds, comprises the flight score for the event.
The fifty-point quiz is designed to test basic physics concepts related to flight. The event score for a team is the sum of
the quiz score and the flight score in seconds, with fractions of a second dropped. In the event of a tie, the highest quiz
score wins. If a tie still exists, the team with the fewest flights attempted during the flight window wins.
Event Location and Time:
Math Atrium. The available obstruction-free floor area measures approximately 43 feet by 50 feet.
10:30AM - 11:50AM and 1:00PM - 2:50PM
Apparatus and Materials:
Prior to the competition:
Two "Peck R.O.G." model airplanes may be entered by each team. Kits for the model can be obtained from Peck
Polymers (http://www.peck-polymers.com ) for $4.99 each, or at
other online stores [e.g., http://www.towerhobbies.com]. If the model is out of stock,
seach for "Peck R.O.G." to find other suppliers. Make sure you get the correct model identified in the picture above.
Each model should be clearly marked with the school and team name and should bear the number 1 or 2 at least one half inch in height.
The surfaces (wing, stabilizer and rudder) must conform to the kit outlines, but the models may be otherwise modified as desired
so long as only the materials provided in the kit are used. No material may be substituted or added to the kit contents
other than cement, thread, wire, tape, rubber bands and weight for balance and trim adjustments. The one exception
is that strips of 1/16" square balsa wood may be substituted for the curved laser-cut ribs found in the new version of this kit,
at the team's option. This is the original wing configuration for this model and is easier to cover with paper because
it is flat, but the curved ribs of the updated version may provide better performance. Both the curved-wing and flat-wing
versions of the model will be allowed for this competition. Paper or balsa trim tabs may be added to any of the flight
surfaces as desired, but no tab dimension is to exceed one inch.
Rubber bands: There is no restriction on the type or amount of rubber used;
contestants are to supply the rubber to power their models. The rubber motors used to power the models may be lubricated.
Support Equipment during the competition:
Contestants may bring any tools, equipment and supplies they wish to support their models.
No support equipment or materials will be provided. Tools, equipment and supplies may be brought to the flight area and staged
before the official flight window begins. No additional tools or materials may be brought to the flight area once the flight
window has begun.
Event Rules:
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Teams: Each team shall have two members.
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Quiz: Prior to the start of flight competition each team will take a written quiz worth 50 points,
equivalent to a flight score of 50 seconds. The time allotted for the quiz is 15 minutes.
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Starting Time: Each team shall be assigned a starting time at random prior to the start of the flight competition.
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Ready Area: The team next in line to fly will stage their models and equipment in the designated ready area.
- Flight Area: All flights must be launched from the designated flight area established by the contest officials.
Additionally, all flight-related preparation must take place within the flight area. Only team members and officials are
allowed in the flight area during the competition, and no outside assistance or advice may be given to a team during the
flight window. Any team receiving outside assistance will be disqualified.
- Flight Window: The rubber motors for both models must be in an unwound condition at the start of the flight window.
The contest director will announce the start of the flight window. Once the flight window is open the team may make as many
attempts as possible to launch one of their models into flight. Both models may be used to score flight points and the parts
of both models may be freely interchanged at the team's option. The models must be released from rest on their landing gear and
"Rise Off Ground" (ROG) from a three-point stance on the floor of the flight area. The timekeepers will time each model while
in flight and record the score for each flight in seconds. Flights of less than five seconds duration shall be scored as zero.
Flights which do not properly ROG ("take off") from the floor of the flight area will be disqualified and the time
achieved will not be allowed to contribute to the final team score. Should both models be airborne at the same time,
only the time for the first model launched will be recorded, and no credit will be given for the flight time of the second
model until it has landed and been re-launched. Flights must be launched from within the designated flight area and during
the flight window for the time aloft to count toward the final score. Flights which land after the flight window has closed
will count toward the final score if launched during the window and not otherwise disqualified. One team member at a time
may leave the flight area to retrieve models but one team member must remain within the flight area at all times. Team
members may ask the contest officials for the time remaining in the flight window. The suggested flight window is five minutes,
but may be modified at the option of the Contest Director to accommodate the number of teams entered in the competition.
- Timing: The official time for each flight is defined as the interval from when the model rises off the ground under
its own power until it either touches down on the floor or otherwise ceases motion due to contact with an obstruction.
Additionally, the timekeepers will record the number of flights attempted during the flight window.
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Repairs: Models may be repaired as required during the flight window, but no additional time will be allotted for repairs.
- Impound: Both models and all rubber motors will be turned in to the contest officials at the end
of the flight window and impounded until the end of the competition. This is to prevent multiple teams
from using the same models and rubber. All models and rubber motors will be returned to the teams at the close of the competition.
Judging Criteria:
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Total Score: The time for each flight will be recorded to the nearest second, with all fractions of a second dropped.
The flight score is the sum of the two highest flight times achieved during the flight window provided that the flights were
not otherwise disqualified. The total team score is the sum of the flight and quiz scores.
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Ties: In the event of a tie, the team with the highest quiz score shall be declared the winner.
Should a tie still exist, the team with the fewest flights shall be declared the winner.
- Awards: Gold, Silver, and Bronze medals will be awarded to the teams with the highest three scores, respectively.
Hints and Tips for Competitors:
Improving Performance: There are many techniques which will improve the performance and longevity of rubber-powered model aircraft.
These include:
- Light Weight: Lighter models fly longer, but are more easily damaged and may suffer in performance due to drafts in the room.
Experiment to find the best compromise between light weight and robustness. Considerable weight can be saved by scraping the plastic
propeller with a razor blade to remove a major portion of the plastic material. This approach can also be used to reduce the weight
of the plastic wheels.
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Safe Storage: Preserve your models in good flying condition by storing and transporting them in a box,
such as a cardboard or plastic household storage container.
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Lubrication of the rubber motor: Commercial lubricants are available, or a good lubricant can be made by mixing glycerin and "tincture
of green soap" in equal parts. Both of these can be purchased at drug stores. Allow the green soap to stand open
for a day or so to allow the alcohol to evaporate and then mix the lubricant and store in a sealed container.
A small squeeze bottle is a handy storage container since it makes it easy to dispense small quantities of lubricant for use.
Lubricating the propeller bearing with light oil also improves performance.
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Mechanical winders: Models can be wound quickly and more turns put into the motor using a mechanical winder.
These come in a variety of types, but the least expensive ones with a 6:1 gear ratio are appropriate for this event.
The winder will put six turns on the rubber motor for each turn of the winder handle. Higher ratio winders are also available.
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Contest Rubber: Using contest quality rubber strip will dramatically increase the performance of any rubber-powered model.
The most suitable size of rubber for these models is1/16 to 3/32 inch wide rubber strip. Be sure to experiment with
the length of the motor. Generally, the longer the motor the better, since more rubber stores more
energy and permits more turns and hence a longer powered portion of the flight. The goal is to have the model touch
down with the propeller still turning and only a few turns remaining on the rubber motor.
friction needs to be minimized. Lubricating the axel supports / bearings with light oil improves performance.
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Trim and Practice: Obtaining good performance from any model requires that it be properly adjusted or "trimmed" for flight. This means
practicing with the model and adjusting it for the best performance. Schedule time in the school gym or other large room and work with the
models until they really perform. Adjust the models so they fly in a smooth circle with a diameter of approximately twenty to thirty feet.
The easiest way to make gentle flight adjustments is to put small amounts of weight on the wingtips, nose or tail of the model. Modeling
clay, available in art supply stores, is particularly useful for this. Adjust the models to fly in a left hand circle and control the
size of the circle by adding small amounts of modeling clay to the left wing tip. Some models will insist on flying in right hand circles,
and if so, then adjust accordingly, but a left hand circle is preferred since the torque exerted on the model by the rubber motor naturally
imparts a left hand turn. If the model stalls ("gallops" nose-up then nose-down) add weight to the nose. If it dives, add weight in small
amounts to the tail. Also note that the thrust line can be adjusted by bending the prop bearing, particularly to the right or left to aid
in obtaining a proper circle. Finally, more drastic adjustments can be made by attaching paper trim tabs to the rear edges of the model
surfaces, but this should be done sparingly, since these adjustments depend on the flying speed of the model and are much harder to control.
Practice and experiment to get the most out of the models.
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Research: There is extensive information available on the Internet related to the subject of obtaining maximum performance
for rubber-powered models. In particular, search for sites related to the Science Olympiad program, which includes the "Wright Stuff"
model airplane event. Much of the information available is directly applicable to this event, including additional specialized
equipment and techniques to increase performance.
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Keep Records: Record flight data in a notebook so that improvements in performance can be tracked and reproduced.
Suggested data include motor dimensions and weight, number of turns, final motor torque and flight duration, along
with notes and observations.
Sources for Supplies and Materials :
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Peck Polymers: The primary source for kits, winders, lubricant and contest rubber strip.
http://www.peck-polymers.com/
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Ryder's Hobby Shops: The Rider's Hobby chain of hobby shops stocks a good selection of materials and supplies including
Peck ROG kits, adhesives, rubber and winders. They carry the Peck Polymers line and can special order these products.
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Indoor Duration: A web site specializing in high performance indoor duration models.
http://www.indoorduration.com/
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National Free Flight Society (NFFS): This is the national organization representing all aspects of Free Flight
Model Aviation. Free Flight means that the models are flown without wires or radio control equipment, and
so are truly free when launched into flight. The site contains much generally useful information, suppliers
and links to Science Olympiad information, including excellent instructions for basic construction and trimming techniques.
http://freeflight.org
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The Internet: The above sources will provide good basic information for this event, but there is much more available.
Research the topic on the Internet. Good key words to try: Science Olympiad; Wright Stuff; Indoor Duration; Indoor Model; Free Flight.
