Principles of Flight presentation

Report
The Orlando Youth Aviation Center (OYAC) is sponsoring a
glider competition amongst local students. The purpose of the
competition is to give these local students the opportunity to
utilize their knowledge of aircraft design and performance and
to learn even more by designing, testing, and building gliders
and competing against other local teams of students. The rules
and design requirements for the competition are as follows:
Rules and Restrictions
1. Teams must design and build a glider from scratch. No kit built
gliders are allowed. Other than supplies from a kit, there is no
restriction on the materials used in building the gliders (see rule #2
for other materials not allowed).
2. Do not use metal (including coins), glass, spikes, rocks, gravel, or
any other hard material to construct the glider. The intent of this
rule is to prevent any injuries should the glider come apart or hit a
person. Use of these materials will automatically disqualify the
team from the competition. The Head Judge will make the final
decision as to whether the materials are not allowed.
3. Only one glider per team is allowed. Each team will consist of 3
students.
4. The payload for the gliders will consist of marbles that will be
supplied by the competition coordinators on the day of the
competition. The marbles will be 0.56 inches in diameter and have
a mass of 3.8 g (0.134 ounces) each.
5. The glider must carry exactly 16 marbles 16 marbles will have a
mass of 2.1 ounces.
6. The marbles must be kept in a single location in the glider,
encased in a single container placed in a single location in the
glider. There is no restriction on the length, width, or height of the
container.
7. In order to prevent marbles from spilling out everywhere during
a hard landing, teams are required to place all of the marbles inside
a sealed sandwich bag when in the glider.
8. The gliders will be hand launched with no power assist
(springs, bungee chords, etc.) or any other device by a team
member in an indoor facility to be designated by the
competition coordinators. The team member must have their
feet planted in a box 12 inches by 12 inches square when
launching the glider. If the person’s foot is outside the box upon
throwing the glider, the flight will have to be redone.
9. No radio control of the gliders is allowed.
10. No glider may have a total weight (including the marbles)
more than 10 ounces (283.5 grams), nor may it have a total
weight less than 6 ounces (170.1 grams). Aircraft with a total
weight less than 6 ounces or greater than 10 ounces will not be
eligible to compete. Again, the 6 and 10 ounce weight limits
include the 2.1 ounces of marbles.
11. The glider must have a minimum wingspan of 2.5 feet (30
inches). This will be measured from wingtip to wingtip with a tape
measure.
12. Ballistic entries are not allowed. In other words, you cannot
toss it like a shot put.
13. Points will be earned by the distance that the glider travels.
One point will be awarded for every foot of gliding distance.
14. Each team will be given a total of 4 flight attempts. The team’s
total score for the competition will be the sum of the scores of all
flight attempts. The competition will be held in four rounds, which
each team being given only one flight attempt per round. Hence,
you cannot fly twice in one round and not at all in another.
15. The distance glided will be measured using the nose of the
aircraft, regardless of what position the aircraft is in upon
landing.
16. Any flight that results in the aircraft breaking into multiple
pieces will be reduced by 25%. Hence, if the glider travels 40 feet
but any piece breaks off upon landing, the distance will be
scored as 30 feet. This includes the marbles, which must remain
inside the glider during the impact of landing for that flight to
count. The only exception is if the aircraft travels the entire
length of the facility being used (likely an indoor atrium) and hits
the wall at the far end of the facility. If impact with the wall
causes the aircraft to break into multiple pieces, that flight will
still count with no penalty. Any flight during which the aircraft
remains completely intact will count in full, regardless of
whether the plane reaches the far wall or not.
17. No wheels are allowed on the glider. It must slide to a halt
on the ground, not roll to a stop.
18. The distance glided by the aircraft will be measured in a
straight line from the starting point using distance markers on
the ground, as shown below. The measured distance will be
determined only by the distance from the starting point
perpendicular to the distance markers. In other words, even
though the aircraft may travel the distance shown by the solid
line below, the measured distance will be that of the dashed
line. It is up to the teams to design and develop an aircraft that
is directionally stable.
19. The competition coordinators will set up a boundary (shown by
the very thick lines below) which are guaranteed to be clear of
obstacles and people. If an aircraft strays outside of this boundary
it may hit a wall or support column and suffer damage. As
mentioned above, if any pieces break off from the glider its flight
will be reduced by 25%. If the glider does not suffer damage
outside of the boundary, there is no penalty. The boundary is set
up to define the region in which the glider is guaranteed to not be
in danger of hitting a wall or other structure. It will be
approximately 10 feet wide and again it is up to the teams to build
a glider that can fly straight and thus not stray outside of this safe
zone.
CHALLENGE
1.Participants create a glider that stays in
flight for the greatest elapsed time.
2.The glider must be designed to be
launched from a catapult that is provided
on site.
3.The design process is documented in a
notebook that is submitted for
evaluation.
• Students must be instructed by their teachers on the proper
use of cyanoacrylate (CA) glue.
REGULATIONS
A. Students are required to provide and wear safety eyewear for this
event.
B. Participants are not allowed to construct a glider without a
completed technical drawing in their documentation notebooks.
C. A standard three (3)-ring binder, with a clear front sleeve for a
cover page, is required. The cover page must include the event title,
the conference city and state, and the year. The inside of the binder
must include the following single-sided, 8½" x 11" pages:
1. Title page with event title, conference city and state, and the year
2. Full-size metric technical drawing with dimensions of the glider to
be built; 11" x 17" paper may be folded to fit in the sheet protector.
3. Pictures of two (2) test gliders will be included in the binder
4. Flight log for each pictured test glider (see Flight Log sample
below)
Materials
(SUPPLIED BY THE PARTICIPANT) (Participants may have only one [1]
of each wooden part. Extra wooden parts will not be allowed, so
wood should be chosen carefully.)
1. Balsa and/or basswood plus ballast material
a. fuselage blank, 3mm (⅛") thick x 13mm (½") wide x
300mm (11⅞") long
b. wing blank, 1.5mm (1/16") thick x 77mm (3") wide x
300mm (11⅞") long
c. stabilizer and fin blank, .75mm (1/32") thick x 51mm (2")
wide x 150mm (5⅞") long
d. wooden shark’s tooth hook, 3mm (⅛") thick x 6.5mm (¼")
wide x 20mm (¾") long, glued to the bottom of the fuselage;
a shark’s tooth cut into the fuselage will also be permitted.
2. A maximum of five (5) grams of ballast, such as clay, fun tack,
poster tack, or similar material to be used for balance trim
Tolerances are as follows:
1. Fuselage: 298mm to 300mm long
2. Shark’s tooth hook: 18mm to 20mm long x 6mm wide
Templates, jigs, and fixtures that MAY be used in constructing
gliders; these are to help facilitate fast and accurate construction.
1. Templates, jigs, and fixtures must be developed and built by
students.
Sanding blocks —These may have two (2) grits affixed to the top
and bottom; grits are chosen by the student.
4. Traction plate with sandpaper (150mm x 300mm maximum)
attached to a thin piece of rigid material, i.e., plywood, foam core
board, press board, cardboard, plastic, etc.
5. Dihedral fixture — This is an all-wood apparatus that assists in
sanding the critical dihedral joints and that secures the model as
the glue dries to ensure a precise prototype.
TIME LIMITS
A. Participants have ninety (90) minutes to construct a glider.
B. Participants are given a maximum of thirty (30) minutes for
trimming (test flights) of their glider.
ATTIRE AND SAFETY EYEWEAR
TSA competition attire, as described in the Competitive Events
Attire section of this guide, is required.
Participants are required to provide and wear safety-approved
eyewear during all phases of this event. Prescription eyewear will
need to have side shields to be considered safety eyewear. Should
a participant remove his/her eyewear during the event, s/he will
be reminded once to replace it. If there is a second infraction, the
participant will be asked to leave the competition.
Tool Box (254mm x 254mm x 508mm):
(Labeled with School Name, Address and Advisor’s cell phone)
• Cutting Devices – X’acto knives, utility knives
• Glue – super glue or cyanoacrylate (CA) glue, debonding liquid
• Fastening devices (pins, clamps, tape)
• Cutting surface
• Rulers
• Sanding paper
• Pens and pencils with sharpener
• Wax paper
• Pliers
• Safety glasses
A. Participants report to the event area at the time and place
stated in the conference program with their metric technical
drawing,
notebooks, tools, and supplies.
B. Participants use their metric technical drawing to fabricate a
glider. The technical drawing may be hand-drawn using
mechanical drawing instruments OR done using CAD.
C. Participants may use templates, jigs, and fixtures for constructing
the glider.
http://www.bsu.edu/academy/webwings/model/index.html
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E. Notebooks are evaluated.
F. Participants have four (4) opportunities to fly their gliders for
official times. The combined flight time of the best three (3) of
the four (4) flights is used to determine the ten (10) finalists.
Dihedral (courtesy divad135) http://www.instructables.com/id/How-to-Make-Hand-Gliders/step6/Adding-Dihedral/
(As said above) Any hand glider that you will ever build will need dihedral on the main
wing to stabilize it in flight, or it will nosedive.
Here are 2 basic rules:
If the plane has wingspan under 30 inches: 1degree for every 1 inch of wing span.
If the plane has a wingspan over 30 inches: 0.5 degrees for every 1 inch of wingspan.
Before considering the moment arm, however, the tail area to be used must first be
determined. On the average glider of twenty inch wing span and 42 or 45 square inches of
area, a stabilizer of eight inch span, and 14 or 16 square inches in area is most efficient. This
constitutes about 23% of the wing area and has been found to work better than any other
set-up. With this given amount of stabilizer area a moment arm of between four and six
inches has proven its efficiency.
After considering the elevator area, the next step is to find how much rudder area is required.
This usually is best found by taking approximately 14% of the wing area. By WALTER L. WEITNER
DIHEDRAL - How Much is Enough? -by Clay Ramskill
In general, the more dihedral an aircraft has, the more it will tend to self-right to wings level when upset from
straight and level flight. This little bit of roll stability makes the plane easier to fly because the pilot doesn't have to be
constantly fighting to maintain wings level. Note the top two drawings in the figure - once we are no longer level, the
lower wing is effectively a bit longer, and the lift forces forces on the lower wing are pointed more straight up. Also, since
the figure shows a high wing plane, the CG of the plane is offset toward the high wing. All these situations tend to force
the plane back to a wings level condition initially, before the plane begins turning or skidding sideways.
But the conditions described above won't last long. Also note that we now have the lift forces on the higher wing
pushing sideways; this will cause the plane to skid sideways, turn, or both. Assuming no corrections from the pilot, what
now happens is largely dependent upon the size of the rudder/fin combination! If the fin/rudder area is just right, the
skid continues just enough for the dihedral effect of the wing to return us to wings level. Too much area in the
fin/rudder, and we turn without skidding. Centripetal force from the turn negates all the self-righting effects, and we fly
in balanced flight, but in an ever increasing wing and nose-down spiral - this is called spiral instability. Too little
fin/rudder area, and the skid continues even as we pass wings level, resulting in over correction, and the plane rolls and
skids, oscillating like a drunken sailor - this is called dutch roll.
Although the above discussion is more important to glider and free-flight pilots, it brings us to look at how dihedral
affects a plane in skidding flight - and the good and bad sides of the dihedral effect. Note in the figure what happens to a
plane with dihedral when in a skid, or unbalanced flight. This condition can occur with the pilots deflection of the rudder,
or when a wind gust hits the plane from the side. The large discrepancy in angle of attack between the two wings causes
the plane to roll away from the direction of the skid.
The dihedral effect is beneficial in self righting, gives us roll coupling with rudder application, and unfortunately, also
gives us roll away from a side wind gust. Incidentally, sweeping a wing back also gives us dihedral effect - with about 5
degrees of sweep being equivalent to 1 degree of dihedral.
While roll coupling is essential to a trainer with no ailerons, its not good for aerobatic and combat aircraft. Most
acrobatic and pattern models will have no dihedral. Military planes, with swept wings for speed, often use negative
dihedral to counter the dihedral effects from the wing sweep - the Harrier, A7 Corsair, and C5 transport come to mind.
And while trainers usually have quite a bit of dihedral, and are wonderfully stable in normal flight, we've all seen
them turn vicious in a gusty crosswind, during take off and landing, and even while taxiing on the field.
How much dihedral is enough?? For most of us, then, the answer is - Only enough to give us the roll stability we need,
commensurate with our flying skills!
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