Landing Precision

[CzarMark]

While waiting for the return of my Breeze for warranty repairs, I decided to make a landing pad. I had some 1/4" acrylic that I wasn't using, so I made (2) 24" diameter landing pads (one is intended for a friend). The first pad I painted Candy Apple Red with a White circle and White H. The second pad is Dark Green with a White circle and White H.

I got my Breeze back from the repair shop, and it works great. I decided to use my new Red landing pad because the grass is a little long and I am tired of cleaning my props of grass stains from landing in the grass. After my first flight with my repaired Breeze I attempted a landing using 'Land Now' after lining up the drone with the pad. No joy. The Breeze appeared to drift forward and landed approximately 18" from the center of the landing pad directly in front of the pad (between the pad and me). Long story short, I landed on the pad once out of thirty (1 / 30) tries! And 90% of the time, the Breeze drifted forward and landed approximately 18" from the center of the landing pad in the same direction.

I could not figure out the problem, so I decided I would try again the next day and run multiple tests with both the Red and Green landing pads. I even tested turning the landing pads over - They appear all White as I had applied a base coat of White to both landing pads. Same story - a success rate of 1 / 30 with the persistent drift problem.

The day I did these tests, the winds were calm. I tried many different methods of landing including:
- 'Land Now' from different altitudes. I did this by eyeballing the drone as it hovered over the landing pad.
- 'Land Now' from the lowest altitude I could get by throttling down (approximately 12" - 18" over the landing pad), and turning the camera straight down to try to line up.
- 'Return to Home' from different locations and altitudes. (Return to Home never landed on either landing pad).
- Attempted landings on the Red pad, Green pad, and the White pad.

A couple of questions for the community:
- Do you use a landing pad?
- What level of precision are you experiencing in landing where you took off from (proximity)?
- What is your success rate in landing where you took off from or where you intended to land?
- How close does your Breeze land to where it took off from when using 'Return to Home' (proximity)?
- Could the infra red sensor be causing a problem landing on the acrylic landing pads?
- Could the color of the landing pads be a problem?
- What else could be causing the drift I am seeing?

Any thoughts are greatly appreciated.

 

[NorWiscPilot]

While waiting for the return of my Breeze for warranty repairs, I decided to make a landing pad. I had some 1/4" acrylic that I wasn't using, so I made (2) 24" diameter landing pads (one is intended for a friend). The first pad I painted Candy Apple Red with a White circle and White H. The second pad is Dark Green with a White circle and White H.

I got my Breeze back from the repair shop, and it works great. I decided to use my new Red landing pad because the grass is a little long and I am tired of cleaning my props of grass stains from landing in the grass. After my first flight with my repaired Breeze I attempted a landing using 'Land Now' after lining up the drone with the pad. No joy. The Breeze appeared to drift forward and landed approximately 18" from the center of the landing pad directly in front of the pad (between the pad and me). Long story short, I landed on the pad once out of thirty (1 / 30) tries! And 90% of the time, the Breeze drifted forward and landed approximately 18" from the center of the landing pad in the same direction.

I could not figure out the problem, so I decided I would try again the next day and run multiple tests with both the Red and Green landing pads. I even tested turning the landing pads over - They appear all White as I had applied a base coat of White to both landing pads. Same story - a success rate of 1 / 30 with the persistent drift problem.

The day I did these tests, the winds were calm. I tried many different methods of landing including:
- 'Land Now' from different altitudes. I did this by eyeballing the drone as it hovered over the landing pad.
- 'Land Now' from the lowest altitude I could get by throttling down (approximately 12" - 18" over the landing pad), and turning the camera straight down to try to line up.
- 'Return to Home' from different locations and altitudes. (Return to Home never landed on either landing pad).
- Attempted landings on the Red pad, Green pad, and the White pad.

A couple of questions for the community:
- Do you use a landing pad?
- What level of precision are you experiencing in landing where you took off from (proximity)?
- What is your success rate in landing where you took off from or where you intended to land?
- How close does your Breeze land to where it took off from when using 'Return to Home' (proximity)?
- Could the infra red sensor be causing a problem landing on the acrylic landing pads?
- Could the color of the landing pads be a problem?
- What else could be causing the drift I am seeing?

Any thoughts are greatly appreciated.

Question: Does your craft drift when you try to land without the pads?

The simplest of theories, if it does not drift when you simply land in the grass, is prop wash coming off the pads and pushing your craft away.

Jeff

 

[ThunderChicken]

Have you taken off from the pad? What happens then?
There is phenomenon that full sized helicopters try to avoid when landing because it almost always results in a crash. I forgot what it is called. The rotor wash starts to circulate and comes back down on top of the rotor and causes a stall and the helicopter moves to one side and then lays down. There was police helicopter here that crashed this way. That might be what's going with your slick as glass landing pad.

 

[CzarMark]

Question: Does your craft drift when you try to land without the pads?

The simplest of theories, if it does not drift when you simply land in the grass, is prop wash coming off the pads and pushing your craft away.

Jeff

I can't say specifically if the Breeze drifts on landing without the landing pad, however, I did attempt a few landings to a spot in the grass. I was unable to hit the spot and I remember thinking at the time that it was due to my own depth perception as I did it off to the side.

Having said that, I do believe that prop wash is affecting my landings. I did some research on prop wash and landing on landing pads, and while I couldn't find anything specific to the Breeze, I did find that many pilots with other [higher end] Yuneec products did mention that a directly vertical landing was difficult. I noticed in discussions and videos that many pilots landed while moving forward slightly to avoid the prop wash. I don't know if this maneuver is possible with the Breeze.

 

[CzarMark]

Have you taken off from the pad? What happens then?
There is phenomenon that full sized helicopters try to avoid when landing because it almost always results in a crash. I forgot what it is called. The rotor wash starts to circulate and comes back down on top of the rotor and causes a stall and the helicopter moves to one side and then lays down. There was police helicopter here that crashed this way. That might be what's going with your slick as glass landing pad.

Yes - in all of the testing I mentioned in my original post I started by taking off from the landing pad. I don't recall any deviation of the Breeze when it took off, however, I will have to look more closely during my next session.

UPDATE: After more testing with a modified landing pad, I did not notice any deviation when taking off from the landing pad.

 

[ThunderChicken]

Louisville Police Helicopter Crashes in Eastern Jefferson County - Louisville Metro Police Department - Louisville, Kentucky - 2006-08-02
The news story does not verify the rotor wash but I do remember hearing one of the FAA investigators mention that Rotor Wash was the probable cause of the crash based on eye witness reports.

 

[CzarMark]

UPDATE TO MY ORIGINAL POST

After doing some research into prop wash based on @NorWiscPilot's suggestion, I felt this was the most logical thing to focus on. As a result, I modified one of my landing pads by drilling 1/4" holes every 1-1/4" and staggering every row. I thought this might allow the prop wash to flow through the pad and not have as much effect on landing. I then did some testing. While I did not experience great results, I was 3 times more successfully - I landed on the pad 3 / 30 times and had several 3 point landings.

I did notice a few things and came up with some conclusions:
- For comparison purposes, I began my testing with the landing pad on the ground. As expected, I went 0 / 6 as the prop wash could not flow beneath the pad.
- For the remainder of my testing, I placed (2) 2 x 4s under the landing pad (raising it 3-1/2" off the ground). After this, I was much more successful landing on the pad 3 / 24 times.
- After I raised the landing pad, I noticed that when the Breeze approached the edge of the pad, it would raise up approximately 3" - 4". I believe this indicates that the infrared sensor is, in fact, playing a role. This surprised me as it was very sunny outside.
- I suspect that my depth perception is also a part of the problem. I attempted to land the Breeze on the pad 10 times by looking at the Breeze when lining up. I was 0 / 10. To test this, with the camera facing down, I would look at the video on my phone while lining up. This proved to be much more successful - all 3 of my successful landings were accomplished in this manner.
- While the wind was fairly calm, there were occasional gusts. Surprisingly, my first successful landing on the pad was with a wind from my right. I was able to account for it and land on the pad.
- All of my tests were executed by throttling down (descending) as low as the Breeze would allow. Unfortunately, I believe this is the critical success factor in precision landing. The limitation of only being able to descend to 12" - 18" by throttling down is what makes precision landing difficult, in my opinion. Combined with the requirement to press the 'Land Now' button before touching down allows time for things to affect the landing. That time includes the time it takes to press the 'Land Now' button after lining up and the time for the command to be sent from the phone to the Breeze. I believe that if the pilot could throttle down all the way to the ground, precision landing would be much more successful.

I have one more set of tests to run. I am going to elevate the second landing pad which I have not modified. That should tell me if, in fact, the holes are allowing the prop wash to flow through.

 

[allena99]

I think the condition described in post #2 is "Ground Effect". As the rotor wash gets near the ground, the air flow reflected back has an effect on the stability. Fixed wing aircraft are affected the same way by the downwash from the wings airfoil as it gets near the runway. The more serious condition described in #3 is called VRS, or Vortex Ring State. That can cause loss of lift at any altitude and usually occurs when the craft is descending in a straight line, and at too high a rate.

 

[CzarMark]

UPDATE #2

Over the weekend I had a chance to do additional testing using both landing pads - one with holes and one without holes. Much to my surprise, I was slightly more successful (5 / 15) with the pad without holes compared to the other pad with holes (4 / 15). All tests were done by turning the camera down and watching the video on my phone to align the Breeze with the landing pad. Also, both pads were elevated approximately 3-1/2" off of the ground.

Some new conclusions:
- While prop wash still seems to have an effect, the holes in the landing pad did not mitigate that problem.
- I found that attempting to land at a slightly higher altitude (3' - 4') resulted in a higher success rate. This really surprised me. I still feel that it would be advantageous to have full throttle control (all the way to the ground), however, that doesn't seem to be as big of an issue as I first thought.

Bottom Line: Precision landings with the Breeze requires a great deal of practice. Also, at least for now, I'm not sure the time is warranted for precision landings due to the time required for lining up. That additional time is limited from the battery standpoint.

 

[domdeg]

Hello,

I am currently designing a landing pad. I want it to be the most functional, quality, etc pad to use. Does anyone have any advice/thoughts on what it should include? Size? What I should not include/watch for? Material? Etc... thanks!!!

 

[NiG]

I'm using a siliconic desktop pad 65X45 cm (different sizes are available on IKEA - product code: 667.035.00) - it's foldable, washable and heavy enough to do not be blown away by the propellers.

 

[ninjagaiden]

Matte surface - some nice high contrast stripes to help the optical flow camera.

 

[CAMXposure]

Day 2 of flying - I lean on it is a toy for the most part- a cool one at that...??

 

[CAMXposure]

A thought on a landing pad.... a open grate on a platform - if thrust wash theory is fault..???