|Nov 21, 2009, 02:12 PM|
Joined Nov 2006
My grass field is too rough and the prop too close to the grass with my new Appreentice 15e from eflite, to land,taxi, and take off properly....especially with a field which is just a farm field mowed with a lawn mower.
It took me about 9 or 10 different attempts to modify the apprentice (which flies exceptionally well..good power, good stability.. good everyting in the air) to land taxi and take-off on my grass field. I should note that the plane as supplied did just fine on black-top strips in dead calm weather. It did not do very well on the local RC CLUB grass field which is VERY smooth as fields go.
WHAT DID WORK WELL: (i'll tell of all the failures at the end)
pic #1 shows plane with new grass gear that works great for me. The lower end of the prop (standard prop that came with the arf plane) is 3 1/2 inches above the floor. The tip of the elevator (neutral position) is 4 3/4 inches to floor. For all of you who worry that the angle of wing attack might be too great (as I did), no problem works just fine and prop cuts less grass.
pic #1 & #3 Show the 3 1/2 inch light flite foam wheels (Dave Brown I think) which are used on the nose and main gear. NO***!!! 2.5 , 2.75, 3, 3.25 DID NOT work....I tried them all ..yep that's 8each wasted wheels to purchase!! I also bought a set of 4inch which I did not need and returned for refund unopened. (It is a good 80 miles round trip to my local RC Dealer)
pic #5 & #6 Show bends in 5/32 nose gear: 1 1/8 " from end of wire to start of flat for screw, 1/4" flat, 1/2" to first edge of steering arm (used as spacer at the moment ..right up aganist coils of gear) From other edge of steering arm(against coils) up to right angle bend is 4 inches, 2 1/8" after rt angle bend(where wheel mounts). When making nose gear, slip the steering arm on the short end of 5/32 wire up against the coils..measure 1 7/8' down from the stearing arm and cut off wire ( I used dremel cut off wheel). THIS must be no longer than 1 7/8" because it goes into openiing where power wires are for the motor**!*. http://www.hobbypeople.net/gallery/566935.asp (source for nose wire).
pic #4 Shows nose gear mount (origional) drilled out with #17 drill..must be sharp...set screw for gear must be removed conpletely... drill all the way down through the bottom of the polycarb bulk head (to give better leverage on rough landings) ***DO NOT DRILL too far ..just through the bottom... because you are drilling into the hole with the motor power wires***. Obviously check that wires are out of way when drilling. Run drill up and down several times to get proper clearance with #17 drill bit. Drill slowly on first pass ..clearing drill many times to prevent breaking the origional steering arm.
I used my dremil cut-off wheel to grind the 1/4" long flat for the set screw... had the motor parallel to the wire and lightly ran the grind wheel up and down the center of the wire between marks (not too deep) to give a concave flat which worked well.
pic #2 Shows control rod modification insid plane. After I had broken the little plastic tit off the clevis on 5or6 of them (landing), I cut the end off a spare aileron control rod for my typhoon-2, attached it to the existing control rod with 2each 1/8' brass collars (could adjust but a bit stronger then the plastic thing) ...left the wing off while adjusting this to taxi properly. This is another reason for the new external steering arm shown in the other photos... I purchased a second rudder servo and Y-harness.. expected to need to mount this servo rear of the battery box benind the foam bulkhead and run a stronger metal rod outside of battery box up to the steering arm..so far have not needed it (but did not return the servo).
pic #3 & #6 Not too well shown but it is very important that the tip of the wheel which touches the ground ... be directly in line with the 1 1/8 inches of the gear wire which mounts in the plane. This gives the least torque aginst the servo on landing. pics #5 & #6 show how the long end of the 5/32" wire was bent out just a bit (a couple of inches from the coils) and then over-bent at the 90 degree bend ...to make the axle perpendicular the 1 7/8' mounting shaft... and still have room to center the 3 1/2' tire.
|Nov 25, 2009, 09:30 PM|
Joined Nov 2006
15E APPERNTICE GRASS LANDING GEAR things that didn't work
First one more of the things that did work: Main gear OK as is.. just replaced the little wheels with 3 1/2' "Lite Foam Wheels"
1st failure: straightened out the origional gear so a larger wheel would fit...still prop cut too much grass.
2nd failure: un wound one turn of the origional gear to give more clearance...nose wheel bent back on each grass landing.
3rd failure: unable to find the origional metric size piano wire...I ground down the end of 1/8" piano wire to fit in the poly-carb mount, & wound 4 coils and made new front gear.(happened to have a lathe with tool post grinder)..this gear just bent where it was ground down to metric size..upon landing.
4 thru 6 failures: drilled out the poly-carb with #17 drill, & used a generic 5/32 front gear (much like the one that worked finally) however these were all improperly centered ..& gave too much torque when landing.. broke away from servo arm.
[Well that is all the story] (So far 3ea have been made and used successfully myself and 2others)
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