MSR carbon rod reinforced landing gear + permanent 250mAh Li-Po holder
Anyone who has broken a set of landing gear on the MSR say "aye". Aye. Times four.
I am going to explain how to make your stock landing gear ten times (if not more) stronger and (optional) add a permanent 250mAh battery holder.
This mod will add less than 2g weight to your chopper (just a guess - no scale yet).
I am quite new to using carbon fiber rod but this much I know. It is strong and brittle and splinters a little when cutting it with side-cutters SO make each piece about 1cm longer than your actual finished length and use a flat file to grind down the splintered ends. Important: Each support piece you make should fit tight enough that it will hold in place with no adhesive. If any piece you make is too long you will add stress to the existing gear and if any piece you make is too short it will not accomplish anything except add weight.
For the purpose of my explanation:
- a skid is the ski that rests on your table
- a frame consists of a battery holder, 2 T-mounts, 2 frame-rails and 2 cross-members
- a T-mount is the pin + support (shaped like a 'T') that slides into your chopper's main frame
- a frame-rail is the curved plastic piece that spans T-mount to T-mount on your frame
- a cross-member is a bar that goes BETWEEN the frame-rails
- a strut is the leg that connects the frame to the skid
What I used:
- a pair of needle-nosed pliers
- a pair of side-cutters
- a flat file
- a triangular needle file
- a hot-melt glue gun
- JB weld (optional)
- a length of 1.5mm carbon fiber rod
- a zip-tie (strap width approximately 3/16")
- some foil tape
- The Force (just kidding)
How to strengthen the landing gear:
- add a cross-member just in front of the rear T-mount then glue into place (this will strengthen the rear T-mount which was the first place I ever broke my gear)
- add a strut in front of every existing strut (use your triangular file to cut a 'V' in the carbon rod so it will actually rest on top of the skid, then file down the other end so it will wedge in between the existing strut and frame-rail, then glue into place
- add a support between the two skids (make it 1 or 2 mm wider than the actual distance between the skids) and also cut a 'V' into both ends with your triangular file so it "clips" onto the top of each skid, then glue into place (if you run your finger sideways across the top of your skid it should feel sharp and this is where you should clip the new support)
How to add the 250mAh holder:
- cut a piece of the zip-tie strap about 3 inches long
- about 1.5cm from one end, make a 90 degree bend
- snug the battery against this 90 degree bend and make a mark where you need to make your second 90 degree bend, then bend (I had to bend the zip-tie strap back to itself and when it unfolded itself I was left with about a 90 degree bend)
- make sure the battery fits snugly between both 90 degree bends
- trim the second side so it's about the same height as the first (1.5cm)
- now you are ready to glue into place but this is tricky
- push the battery holder forward so that it is against the new carbon struts and release the sideways pressure so that the sideways force pushes against the existing struts, then glue only one side into place making sure that you keep the new holder vertical
- once the glue has hardened, repeat for the other side
- it is important that you do this while holding the battery in place as a guide
- it is important that as you glue the second side you put good pressure upwards to keep the battery as tight as possible
- when I glued my second side it slid down very slightly and I was forced to add 6 strips of foil tape to the bottom of my battery so it would fit snugly
- it is necessary to add quite a bit of glue to hold the holder in place as it is going to be holding 7.3g
In theory, I could join my 250 and 120 batteries with a Y-harness and have a 370mAh battery. But I do not care to put this kind of stress on my motor so I will not be doing this. But I did take some pictures with both batteries in place just for fun.
This landing gear mod does not affect the way my chopper flies whatsoever. I still get 5 minute flights with the 120's and a 9 minute flight with the 250 and added stability. I knew the flimsy landing gear could be beefed up and I needed to find a better way than velcro or a rubber band to hold the 250mAh in place. I am starting to like the hot glue gun better than the JB weld as it does not crack but it is messier to work with.