The first line in the flight manual should read: "You will crash".

The stock landing gear on my 3DR hexacopter are fine for experienced pilots, but while learning to fly, you will crash.  At the very least you will make hard landings.

I removed the surviving polycarbon landing gear and replaced them with much more forgiving parts.

I Ty-wrapped three 1/2-inch foam pipe insulators purchased at our local home improvement store.  Then I cut the top of three Easton 9-inch practice balls and shoved them into the "T".  While this photo doesn't show it, one of the Ty-Wraps goes through the ball to help keep it secure on the insulator "T".

Do not try to use the hard plastic Whiffle balls from Target or Wal Mart.  They are not flexible and difficult to work with. The Easton practice balls are pliable and can be cut with scissors.

Note also that I painted the outboard balls black and left the "forward" ball in its native fluorescent green.  This really helps with my orientation of the copter in flight.

These are temporary while I learn to fly proficiently.  The balls are in the direct down-wash of the propellers and have to be contributing to my yaw problem.  I suspect that this is because the training wheels are on the arms for all of the CCW props, and the CW props are not similarly compromised.

I plan to soon add a camera gimbal, and the balls are too low to the ground, so another solution has to be engineered.

Views: 1236

Comment by Christopher Cooper on September 23, 2012 at 4:02pm

I consider my landing gear to be completely sacrificial. They are just lengths of 1.5mm thick aluminium strip bent into shape.

They have a lot of give and soften the blow of harder landings (see below).

After such a landing I can bend them back into shape and be back in the air in less than a minute.

I'll invest in some prettier, lighter landing gear when I gain a bit more confidence in my landing abilities.

Chris

Comment by Jesse on September 23, 2012 at 7:41pm

Hi Stephen, I tried a similar tactic with my jDrones Hexa, but they rotated around the arms in a hard landing and fairly effectively removed the props... :-(

Have you done anything with the stock PID's for your drone?  I have similar yaw issues when I started out, but I later found a good starting point with the PID's published on the jDrones website, I imagine that they would be close enough to get you started with your 3DR hexa as well

Comment by Stephen R Mann on September 24, 2012 at 7:23am

Mine did rotate at first, but the Ty-wraps need to be at the crook of the "T", tight, and passing one through the ball.  I have made many 2- to 3-ft drop-ins and there's no problem with them rotating on the arm.


Distributor
Comment by Dany Thivierge on September 24, 2012 at 8:42am

your foam seems to touch your motor.. :( will not really help you to fly better but will sure take the blow of the fall! :) 


Developer
Comment by Rob_Lefebvre on September 24, 2012 at 8:45am

Christopher, I really like your landing gear design.  Simple and effective.  I think you could make those out of spring-steel, and then they won't need to be sacrificial anymore.  If you could find the right raw material, it wouldn't weigh much more than those for the same effectiveness.

Comment by Guy Van Rentergem on September 24, 2012 at 9:40am

Here is my solution. I use big cable ties. Can adsorbe quit a shock. But when it is freezing outside the nylon become brittle and break.

Comment by Stephen R Mann on September 24, 2012 at 11:54am

Danny - you are right.  I use the foam as a carrying "handle" and it slid into the motor.  Good catch.

Comment by Craig Fraser on September 26, 2012 at 10:26am

Right now I use booties made out of pool noodle, half a ~2" cross-section tightly cable-tied to each foot. The ends of the 3DR legs really grab/stick into stuff too easily, I can't use them plain stock when learning, because when a foot grabs even slightly it wants to tip the whole beast over. Even though these booties are tiny and look like nothing, when I drop my 3DR-B onto concrete from a few feet up, it still bounces...so lots of cushioning without much weight/aerodynamic penalty, disposable and cheap too.

But I had another idea before that that I think is "better" and more durable but I have to refine it, and maybe you guys can help. It is similar to Guy's but should be OK in cold weather. It is using the PVC (I think it is) gutter (eavestrough here in Canada...) available at the likes of Home Depot for cheap, like $10 for 10' or such (yeah, you have to buy a full length). Check out the cross-section of that stuff, imagine a 1" section of it bent (shown ty-rapped, somewhat how I had in mind): decent spring, smooth so it won't catch on stuff, very strong for its light weight. Here are pics of the materials. Keep those ideas coming...

Notice the extra padding around "expensive stuff" on my quad, there's even more when I fly!

Comment by Stephen R Mann on September 26, 2012 at 11:12am

Might work.  But would it give you enough clearance to protect the props if you don't come down square?

I like your CD case cover.  How do you attach it?

Comment by Craig Fraser on September 26, 2012 at 12:10pm

Which one might work? The PVC? It would add a few inches to stock leg height. The booties work fine so far, but I don't fly over concrete. Believe it or not, I actually did my first test flights over concrete/asphalt...convenient but dumb. It is very hard to fully protect props from unlevel landings with just leg height, higher allows more tipping though. Longer arms past the motor mount would help a lot, but worse for other stuff. Putting legs under the motors helps too i.e. the wider the leg stance the less the chance of tipping, but not good for prop performance. Compromises... Props running into grass is not a big prob for me yet.


I do not use the stock quad "stack", except the base plate as a wire cover for the PDB which is getting crowded on mine (I use multiple BEC outputs, plus an accessory connection to the main battery). I do not like how you have to undo the whole stack to make changes/adjustments down low. I think the hex isn't like that. Plus for some stuff, easier to just have the stack on my desk instead of the whole quad. So I made a new base plate that mounts to the stock base plate on four ~12mm brass 3mm-threaded spacers. There are rubber "anti-vibration" spacers under the brass ones too (Dany has new rubber 12mm spacers that combine both these features, but I built this before he had them.) The bottom of the DVD case fits in between the top of these 12mm spacers and the new fiberglass (Cu on bottom) base I made. IOW bashing the case on the outside doesn't directly transfer to the stack/electronics, it just transfers to the flexible DVD case bottom. But there's more lol. There is a hard plastic outer case that is strong enough I can stand on it (when not on frame). I use that by itself or over the DVD case (which is light), gives a convenient carry-strap too. Gotta protect the electronics until I'm more confident...

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