RC India

Broke the ones that came with the frame, so made new ones :)

Kept the length to a bare minimum so the CG remains low also because of its Metal nature, weight had to be in check ...

Nice, is that a wheel below ?

yup :)

had an engineering set, use it for structural purpose :)

Nice, i have also done same but they bend when crash. Add U shape piece under top screw so that when it land - gears will not move upward. Same happen with mine it works, 5-8 landing
;D

This quad gets confused when landing... :-D

@teamnamibia, what you mean ?

I wasnted to put some PVC based small sheets folded to 'U' form and put at the base, but couldnt find any with a medium structural density. If someone has some alternatives to it. Let me know ? It would be better in so many ways and easlyli handle crash landing without breaking anything :)

If you want another fail proof landing skid, You can use two plastic hangers, refer my build log for details.

will increase weight by a lot i guess ?

also, dynamic skits looks more awesome :D

No the plastic hangers are extremely light weight, but is strong.

so 'coolness' factor to them XD

yeah, this wont be aesthetically good. still they do the job!

they do but then again.... no coolness factor :D

btw, what do you suggest, if 2 servo's were to be taken:
2KG quads weight
15cm Shafts length.

How much servo's stall torque should be enough ?

It also depends on the weight of the skids. Do you mean that you are using 2 servos for all 4 retracts?

1 for 2 feet and other for another 2 .

I am not sure how that would work. How can 1 servo retract 2 gears that are at an angle? Anyway, what is the weight of each set of landing skids?

I have a mechanism in mind.
Landing skits wont weigh much, umm 20g ..

parichya, those servos should be of high torque metal gear ones.
and did you changed plans? (from 4 servos to 2 ???)

will bring the cost down XD

I really need some more details of the mechanism to calculate the necessary servo torque. Anyway, from what I just read, it is advisable to use dedicated retract servos for this to avoid damaging your servos. Most retracts for warbirds are air powered and use canisters of compressed gas to provide actuation (controlled by a servo). All the torque calculations I learned in physics class (9th and 10th grade) involved moments of forces (torque) about massless bars or bars of uniform weight. Thus, to even try and calculate what you need, I would need details of how far from the COG of each retract you plan to mount the push rods (if you are using them) and other such details. Otherwise, you could follow a TLAR  (that looks about right  ;D ) approach. Just google DIY Quadcopter Retractable landing gear and maybe follow some of those instructions. I found this video (haven't watched the whole thing) http://www.youtube.com/watch?v=rY_srq0Ox-U#ws (http://www.youtube.com/watch?v=rY_srq0Ox-U#ws)

well 2KG on two servos , huh ???
and 15cm is the length of pull roads, then the stall torque is, atleast 15Kg/cm (assuming 1Kg weight on a servo).
but this set up is nowhere comparable to retract landing skids, they don't use normal servos, those are servos designed to match the criteria.

I have a different mechanism in mind, it will take the load away from the servo when on the ground. but just in case of structural failure it should withstand it. I calculated a bit and it seems that servo with a stall torque of 18.7KG-> take it as 20Kg should do the trick.
How much will those cost ? Metal geared ones.

As per this site: http://www.servodatabase.com/servos/power-hd?page=2 (http://www.servodatabase.com/servos/power-hd?page=2) each servo will cost you $62 and weigh 52 grams. Look at this: http://www.amazon.in/Hitec-RCD-HS-5765MH-Voltage-Metal/dp/B005H5TA4U?tag=googinhydr18418-21 (http://www.amazon.in/Hitec-RCD-HS-5765MH-Voltage-Metal/dp/B005H5TA4U?tag=googinhydr18418-21)

Alright ..

sooraj ?

Well, thanks for waiting,
Here is a mind blowing auction deal,
10pcs of special landing gear servos :
http://www.ebay.com/itm/Hitec-Servo-HS-75BB-retract-quantity-10-/381073939809?pt=Radio_Control_Parts_Accessories&hash=item58b9c6dd61 (http://www.ebay.com/itm/Hitec-Servo-HS-75BB-retract-quantity-10-/381073939809?pt=Radio_Control_Parts_Accessories&hash=item58b9c6dd61)

how much will it cost ?

and these are nylon geared ..

sorry, that one shipping not provided, :banghead:
I will get back to you later.

ph, ok