A fairly simple, robust Catapult Launch Glider. Although the construction is within reach of 10yr olds, obviously the assistance of supervisors will be necessary and the following construction steps are split into a) preparatory work by the supervisor and b) construction steps for the beginner.
I have built a few and trimmed them - including a V tail version(no0t recommended for beginners as it is more difficult to trim), and all have been capable of 30+ sec flights in still air when trimmed.
The following build steps are taken from "Powerpoint" slides done for members of the Australian Air League.
Plan = I will forward pdf's if required on receiving addresses via PM.
John
Supervisors preliminary work and basic tools required.The Supervisor would be recommended to make a short kit as shown.
Preparing wing / tail blanks, producing a basic kit of parts.
Student's work - stage 1. shaping wing and tail.
Shaping the LE, TE is optional but is advised both to save weight, reduce roll inertia and improve the glide
Student Stage 2.
Shaping LE radius and adding dihedral.
Again shaping the LE radius is optional, but is relatively simple - (practise on scrap first) and improves the glide.
NOTE READ THIS AS PART OF STAGE 2 IN PREVIOUS POST
This is a tip on sanding the dihedral joints. With a little care it works well - use a fresh piece of sandpaper and sand slowly, inspecting often and checking the dihedral angle against the support block.
Stage 3 Tail Plane and Fin. Again it is worthwhile to spend teh small amount of time on thinning and shaping these parts.
Stage 4 - Fuselage and Fin. Note that I leave approx 1mm or slightly less of the fin protruding below the fuse. bottom.
Also be sure to place the flat side of the fin against the fuse. stick - ie curved , aurfoiled side out.
What an excellent design for introducing CLG to air-minded youth
Thanks Jeremy. I still have a few more assembly steps - having a little hassle uploading at the moment. I'll get back to it later.
John
It might be a good idea to also upload the material to the Plans Gallery
Thanks Jeremy, I will be loading the plans to the plan gallery to accompany this set of construction steps.
Step 5 - gluing wing to fuselage, wing TE gussets, sanding tail seat on fuse.
Step 6 Gluing tail to fuselage.
It is best to spot glue(if using CA) the tail on first and then check that the tail tilt is close to correct,before applying more CA to complete the assembly .
If using PVA - then the tail tilt can be carefully adjusted while the assembly is held down with masking tape.
Step 7 - Finishing Touches and Initial Trim Settings
As I am presently having issues with the uploading of the drawings for the Sparrow, i would again advise if anyone is interested to PM me with your email addy and I will forward the Assembly Dwg, and the Full Size Templates and the Initial Trim Settings - all on A4 pdf's.
However here are the Initial Trim Settings.
I have found that it is easier to trim CLG's by going almost straight into the launch trimming as soon as hand glides show that it is not diving and has a gentle left turn(right handed - catapult in the left hand model in the right).
Trim these hand glides at the specified CG using elevator changes - warping the elevator on the right tip of the elevator(up elevator should be most likely). Do not trim these hand glides by changing the nose weight and thus the CG.
Launch trimming should then be started
1. TRIM IS FOR A RIGHT HANDED LAUNCH DIRECTLY INTO WIND.
2. LAUNCH WITH APPROX. 40-45 deg RIGHT BANK ANGLE AND APPROX 50 deg ELEVATION.
3. WHILE ADJUSTING THE TRIM ALWAYS USE A CONSTANT STRETCH AND BANK/LAUNCH ANGLES. THIS IS IMPORTANT AS LAUNCH POWER AND LAUNCH ANGLES ARE PART OF THE TRIMMING PROCESS. DON'T BE AFRAID TO USE A FAIR STRETCH - I PULL BACK A MINIMUM OF 15-20". THE TRIM SETTINGS FOR THE RUDDER PARTICULARLY REDUCE AS THE LAUNCH POWER INCREASES.
4. TRIM SEQUENCE. BALANCE WHERE SHOWN.
ADD A SMALL AMOUNT OF ELEVATOR AND BUDDENBOHM GURNEY FLAP SIZE AND LOCATION AS SHOWN, ON LEFT WING TO OBTAIN SAFE INITIAL GLIDE.
THEN ADJUST RUDDER TO GIVE GOOD TRANSITION WITH MAX. OF APPROX 2/3 SPIRAL TO RIGHT. 1/4 TO HALF IS PREFERRED. THE BUILT IN RUDDER OFFSET SHOULD BE CLOSE.
IF AFTER TRANSITIONING FROM THE CLIMB TO THE GLIDE - THE GLIDER DIVES VERTICALLY TO THE GROUND - ADD MORE "UP ELEVATOR" BY WARPING ONE TIP OF THE ELEVATOR UP AROUND 0.4mm PER TRY - I USE THE RIGHT TIP . DO NOT CHANGE THE CG - IE NOSE WEIGHT.
IF THE GLIDER ROLLS TOO SLOWLY OUT OF THE RIGHT BANK OF THE LAUNCH - ADD BY WARPING THE AREA NEAR THE TIP, A SMALL AMOUNT OF LEFT RUDDER. IF IT TURNS TOO QUICKLY(MOST LIKELY DUE TO SLIGHT ERRORS IN BUILT IN RUDDER OFFSET) - WARP IN A SMALL AMOUNT OF RIGHT RUDDER. IN BOTH CASES ONLY USE SMALL WARPS PER ATTEMPT - AROUND 0.4mm PER TRY AND ONLY NEAR THE TIP OF THE RUDDER.
THE EXTENT OF THE SPIRAL TURN INCREASES WITH DECALAGE. KEEP THE UP ELEVATOR TO THE MINIMUM REQUIRED FOR TRANSITION. UNEXPECTEDLY IT IS ACTUALLY EASIER TO ACHIEVE GOOD LAUNCH TRIM SETTINGS WITH MORE POWER THAN LESS.
FINALLY IMPROVE GLIDE WITH SMALL CG SHIFTS FORWARDS OR BACK AS REQUIRED AND CHECK FOR A SAFE TURN USING WING TIP WEIGHT ON OUTSIDE WING TO OPEN TURN IF NECESSARY. THE GLIDE IS CLOSE TO IDEAL WHEN THE WINGS START A GENTLE ROCKING MOTION.
An early trimming flight at dusk - for calm conditions. Note the transition and the large turning circle.