Article • Crop Protection, Agronomic Insights

InterLock® In Aerial Applications

Jul 16, 2021
WinField United

An FAQ

When using atomizer nozzles, compared to a flat fan, does the use pattern of InterLock change? Does the recommendation change?

No, the recommendation for InterLock does not change if you are using the rotary atomizers. Start at your initial loading rate, 0.5% volume for volume, and watch what it’s doing on your first flight passes. Normally with the rotary you will bring your rate down just a little bit. Probably looking at 0.3 - 0.4% volume for volume for the subsequent loads. But your eye will really tell you what the deposition pattern is looking like. You’ll see it as you fly back on your swath and be able to make your adjustments from there. Most of the guys I know that are running the rotaries are hovering in that 0.3% volume category. That seems to be working quite well.

What is the rate for InterLock when spraying at low water volumes?

For low water volumes, with InterLock, we are still running on volumetric basis through that aircraft. Whether you’re at low or high volume, the reason for that volumetric keeps the ratio of oil to water where we want it to be to get the best activity of the InterLock on droplet formation.

Does the temperature and relative humidity affect the performance of InterLock?

Like all spray applications, temperature has a distinct effect on the application.

  • If you are spraying at higher temperatures, say 35°C to 40°C, InterLock makes the product work because it slows down that evaporation rate we see at those extreme ranges. This is what I have noticed when I do some of my work in South Africa.
  • Coming back to normal temperatures in the northern half of North America, 27°C up to 30°C, InterLock shows good increase in value in terms of deposition.
  • Where the value really comes into play is with herbicides and fungicides in that heat, wet phenomena; humectancy. Adding InterLock into that system, under those conditions, buys us an extra few minutes of wetness that allows those pesticides to work more effectively. However, we have pretty good data showing that at the  igher temperatures, it is still an improvement.

What is the right configuration of the nozzles on my aircraft?

I’ve done fly-in clinics, where you are spending 2 to 3 days with the pilot, getting his plane configured right so you get the deposition you want out of how he flies. Changing deflection angle, changing flight speed, changing the height at which he tends to operate – all of those become variables that we can control. We need to be able to control them so he does it uniformly.

Is there any difference between heli-spraying vs. plane spraying in terms of application and things
you need to remember in terms of droplet size?

For helicopter sprayers, we configure them almost identical to the way we configure a ground rig for two reasons. First there is the newer nozzle technology; it bolts right on and is a wonderful addition to a helicopter sprayer’s boom. The AIXR nozzles are a good example. It does 2 things almost immediately. Droplet size becomes more
uniform and the small droplets that are produced by that nozzle, are significantly lower than some of the older technology (ex: the XR nozzle). So immediately as soon as you bolt on those new nozzles, you’re already doing a better job of spraying even if you stay with the same orifice size. Secondly, with helicopters the flight speed
is so slow you don’t get the wind shear like you would with a fixed wing aircraft. This allows you to configure them like a ground rig. The key on those is the boom width vs. the width of your rotor, and how high you are going to fly. 30m is a pretty common swath width.
With fixed wing we’re relying on two things to create droplets - style of nozzle, including the orifice size, and how fast you are flying. The style of nozzle will determine the initial size of the droplet produced and the speed will affect the droplet size when it hits the wind, as it’s released from the nozzle. The higher the flight speed, the more sheer you get on the droplet. This is true with the CP nozzle for example. You can change the deflection angle, which will change the sheer you get from the aircraft based on the speed. The other is the rotary atomizer. You have a nozzle that is releasing liquid and as it hits that spinning disk, the rotary, which is impacted by the speed at which you are flying. The faster you are flying, the faster it is rotating; that breaks it up into small droplets. This is what will be deposited towards your target.
The key is to remember that adjuvants work through all delivery systems, it all depends what your end game is. If you are spraying fungicides, you want thorough coverage. If you are spraying contact herbicides, you want thorough coverage. If you are spraying something like glyphosate, you don’t need to thoroughly wet all tissues on the plant, but you want to keep it on target. Questions to ask: What am I spraying? What is my goal? This will help
dictate what the adjuvant system will be to give us the best performance of those products.

Can InterLock be used with an electrostatic boom?

We have a bit of data but in general we have not gone in that direction. For the electrostatic boom, one of the theories they work on, for both ground rigs and in the air, is to generate a small droplet between 50 - 100 microns that they can impart an electrical charge to. Using the theory of positive and negative effect, those two will attract to each other and then stick. It does work for some pesticides. It will take charge and you can see these  electrostatic sprayers do a decent job. Not all pesticides can take and hold that charge, therefore it won’t effectively work. If you’re using InterLock in the electrostatic sprayers, it does the same thing as it would through other nozzles and delivery systems, and makes slightly larger droplets. Does that improve the EFS systems? We have no data that suggest we get an improvement. We don’t see anything positive when we add it to the EFS.

With the new wind tunnel for aerial nozzles, is there work being done on rotary atomizers with different screen sizes, reflector plates and blade angles?

This is in our work plan to look at those. We are going to look at CP nozzles first. A higher percentage of applicators are working with that style of nozzle and we want to improve this database first. But rotary is on the wish list. There will be nothing done in 2020 – COVID has shut down our research capability. We have been closed for 2 months and may be closed for another month or two. They are behind at least a year where they want to be.

What are the best patterns you have seen out of a 500 GA (gallon) plane? What nozzles were used? How did it compare to the CP11TT?

I have seen excellent patterns without the addition of products like InterLock on a plane that’s been well configured. When looking at the CP11 nozzle, assuming a flight speed of 120 mph, plus or minus, while holding a good height above target, I’ve seen some very nice 35 - 40 meter swaths with good deposition and no wing vortex issues. This is under normal spraying and wind conditions. Flip side, on a spray day where wind speeds are 5 - 15 km an hour, you start to get variable terrain, and when you’re not holding height above target as uniform as what we see on a flat uniform field – now those variabilities of drift and loss start to get more accentuated. With the addition of InterLock, I’ve seen some tremendous improvement in deposition as variabilities of application increase. Generally, the noisier it gets when you spray, the more evident InterLock is at keeping product on target.
 
Most common complaint – too much oil on the windscreen from doing parallel passes. This is the reason we talk about the rate of InterLock. If consistently seeing lots of oil on your windscreen, drop your rate, closer to that 0.3% mark.
 

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