Matrice 600 Landing Gear Skid Kit

[licensed pilot]

Will this DJI product increase the ground stability of the 600? This thing always "feels" like it is about to tip over...

 

[dougcjohn]

Will this DJI product increase the ground stability of the 600? This thing always "feels" like it is about to tip over...

You have a link to this piece? Can’t visualize it.

I’m a new M600 flyer, still setting up. Flown it a few time less gimbal & Camera. It is a little light on landings but figured that was due to lacking lower gimbal weight and power CG.

You expressing it continues to be light footed with gimbal?

 

[licensed pilot]

You have a link to this piece? Can’t visualize it.

I’m a new M600 flyer, still setting up. Flown it a few time less gimbal & Camera. It is a little light on landings but figured that was due to lacking lower gimbal weight and power CG.

You expressing it continues to be light footed with gimbal?

Yes. If you take time and evaluate the aircraft you will notice it is very top heavy. A police agency I was working with tipped theirs over after landing (pilot error for using CSC instead of what they were taught-left stick down). It was ugly to watch, carbon fiber pieces of propeller flew everywhere (another reason to always have a nice clear LZ). The PD's M600 is back in the air after 2 months and $2K in repairs.
If CSC is not done exactly right and the right stick is lowered a fraction ahead of the left, there's asymmetric acceleration of the motors and it will topple over. Never turn M600 motors off with CSC, always land and let it settle for a couple of seconds then left stick down and hold.

The Inspire and M200 do not sit as high as the 600 thus you will not see this issue. I'm guessing the reason for the tall legs on the 600 is for ground clearance with those big cinema grade cameras. However, DJI should offer shorter legs for XTs, Z and X family. Just looking at it it is obvious the CG is high.

I've never flown the 600 in high winds but I 'm guessing landings must be dicey!!!
Perhaps other pilots can chime in. This is only my experience.

 

[dougcjohn]

Yes. If you take time and evaluate the aircraft you will notice it is very top heavy. A police agency I was working with tipped theirs over after landing (pilot error for using CSC instead of what they were taught-left stick down). It was ugly to watch, carbon fiber pieces of propeller flew everywhere (another reason to always have a nice clear LZ). The PD's M600 is back in the air after 2 months and $2K in repairs.
If CSC is not done exactly right and the right stick is lowered a fraction ahead of the left, there's asymmetric acceleration of the motors and it will topple over. Never turn M600 motors off with CSC, always land and let it settle for a couple of seconds then left stick down and hold.

The Inspire and M200 do not sit as high as the 600 thus you will not see this issue. I'm guessing the reason for the tall legs on the 600 is for ground clearance with those big cinema grade cameras. However, DJI should offer shorter legs for XTs, Z and X family. Just looking at it it is obvious the CG is high.

I've never flown the 600 in high winds but I 'm guessing landings must be dicey!!!
Perhaps other pilots can chime in. This is only my experience.

I noticed it was a bit top heavy without the gimbal. Plus, the motor cutoff isn’t as quick as Inspires or M210.

You bring up a good point, the leg struts could be shortened & re-notched to fit the landing skids. Two carbon tubes to purchase if one wanted both standard & shortened legs. I’ll look at that next time just out of curiosity.

 

[licensed pilot]

I noticed it was a bit top heavy without the gimbal. Plus, the motor cutoff isn’t as quick as Inspires or M210.

You bring up a good point, the leg struts could be shortened & re-notched to fit the landing skids. Two carbon tubes to purchase if one wanted both standard & shortened legs. I’ll look at that next time just out of curiosity.

Just be careful; DJI should warn pilots about this tendency.

 

[dougcjohn]

Just be careful; DJI should warn pilots about this tendency.

On a plus... it’s tame compared to the Yuneec H920 Hex. It too was a large Hex, but it could be very touchy to tip. It’s motors would sometime take several seconds to shutdown and they spun just fast enough to keep the H920 light on it’s skids. The 920 took sometime to get comfortable, in comparison the M600 felt controllable & comfortable after a few landings.

Both are touchy, but the M600 is an improvement!

 

[Farnk666]

If you shorten the legs you will make the problem worse, not reduce it.
The issue here is that the AC has a tall COG and large mass yet a relatively small contact footprint in comparison.
If you shorten the legs, the footprint gets even smaller and the AC will be less steady on its feet.

The kit you posted about looks the same as the setup on the M600 Pro.

Where it can get sketchy is where you are forced to land on even slightly uneven ground - much care required to get it touching down gently and smoothly.

CSC for landing and motor shutdown is definitely not proper procedure - left stick down everytime!

 

[licensed pilot]

If you shorten the legs you will make the problem worse, not reduce it.
The issue here is that the AC has a tall COG and large mass yet a relatively small contact footprint in comparison.
If you shorten the legs, the footprint gets even smaller and the AC will be less steady on its feet.

The kit you posted about looks the same as the setup on the M600 Pro.

Where it can get sketchy is where you are forced to land on even slightly uneven ground - much care required to get it touching down gently and smoothly.

CSC for landing and motor shutdown is definitely not proper procedure - left stick down everytime!

Physics 101, a CG closer to the ground plane makes the AC more stable not less. If you are referring to the two tubes that contact the ground (the footprint) then I agree shortening them will not increase stability.

 

[Farnk666]

Physics 101, a CG closer to the ground plane makes the AC more stable not less. If you are referring to the two tubes that contact the ground (the footprint) then I agree shortening them will not increase stability.

Was more referring to the effect that shortening the leg tubes will bring the "feet" (Horizontal tubes that meet the ground) closer to the AC's midpoint and each other. This will reduce the overall 'on ground' footprint and reduce stability.

Engineering 101.

 

[licensed pilot]

Sorry, but that's just wrong. Reducing the length of of the leg tubes does not do a thing about the length of the footprint, but it does bring the CG lower to the ground plane, making the AC harder to tip.

If you push the top of each model below (in any direction), which one would you tip over with the least amount of applied force?

 

[dougcjohn]

Was more referring to the effect that shortening the leg tubes will bring the "feet" (Horizontal tubes that meet the ground) closer to the AC's midpoint and each other. This will reduce the overall 'on ground' footprint and reduce stability.

Engineering 101.

Head slap... wasn't thinking fixed gear angle, that's correct. With gear down angle fixed, as you shorten the legs the distance between the end points narrows.... smaller triangle. If gear was able to open wider, stance would increase or return to the width of longer struts or if struts were vertical stance would remain constant as CG was altered.

 

[licensed pilot]

There you go. It annoys me to no end that DJI does not warn pilots in the manual and let's them find this the hard way.

The solution is simple, offer the standard long tubes for those who need a high ground clearance and shorter tubes for accommodating the XT, X5 Z3-30 users. Problem solved.

 

[Farnk666]

Sorry, but that's just wrong. Reducing the length of of the leg tubes does not do a thing about the length of the footprint, but it does bring the CG lower to the ground plane, making the AC harder to tip.

If you push the top of each model below (in any direction), which one would you tip over with the least amount of applied force?
View attachment 20362

Not at all - if the angle of the legs remains fixed (as it will in this case) and you shorten the legs, the feet will come closer together, reducing the footprint and resulting stability on the ground.

Your example 'B' assumes that the angle of the legs changes somehow. I don't believe that is possible with the M600 pro.

 

[licensed pilot]

Not at all - if the angle of the legs remains fixed (as it will in this case) and you shorten the legs, the feet will come closer together, reducing the footprint and resulting stability on the ground.

Your example 'B' assumes that the angle of the legs changes somehow. I don't believe that is possible with the M600 pro.

"you shorten the legs, the feet will come closer together, " ????
I said nothing about changing the angle, nor the length of the footprint. Bringing the CG closer to the ground makes the AC more stable. I don't see why that is so difficult to comprehend. I give up.

 

[Farnk666]

"you shorten the legs, the feet will come closer together, " ????
I said nothing about changing the angle, nor the length of the footprint. Bringing the CG closer to the ground makes the AC more stable. I don't see why that is so difficult to comprehend. I give up.

OK, time to try again with small words and pictures. Here we have an M600 Pro with an XTr attached.
View media item 1126
Now lets measure the foot rail separation distance with standard length legs
View media item 1127
Approx 53 cm apart
View media item 1128
Now lets take a measurement from the table surface to the XT's lens while it is pointed down
to find a maximum safe distance to shorten the legs. (View media item 1129About 23 cm)

Now transfer that vertical measurement to the legs to find a logical cut point. 23 cm is close to the leg retraction clamps so we will be conservative and use a measurement of only 20 cm from the table surface.
View media item 1130
Now measure the new foot rail separation (assuming we had actually cut the legs at that point)
View media item 1131
New Foot trail separation distance is approx 40cm.
View media item 1132

So yes, keeping the leg angle the same and shortening the legs as above will bring the foot rails closer together and reduce the M600 Pros lateral footprint by 13 cm and in overall area by 24%

Is that clear enough?

 

[licensed pilot]

OK, time to try again with small words and pictures. Here we have an M600 Pro with an XTr attached.
View media item 1126
Now lets measure the foot rail separation distance with standard length legs
View media item 1127
Approx 53 cm apart
View media item 1128
Now lets take a measurement from the table surface to the XT's lens while it is pointed down
to find a maximum safe distance to shorten the legs. (View media item 1129About 23 cm)

Now transfer that vertical measurement to the legs to find a logical cut point. 23 cm is close to the leg retraction clamps so we will be conservative and use a measurement of only 20 cm from the table surface.
View media item 1130
Now measure the new foot rail separation (assuming we had actually cut the legs at that point)
View media item 1131
New Foot trail separation distance is approx 40cm.
View media item 1132

So yes, keeping the leg angle the same and shortening the legs as above will bring the foot rails closer together and reduce the M600 Pros lateral footprint by 13 cm and in overall area by 24%

Is that clear enough?

Nope; the higher the CG is, the easier the AC is tipped over.