Close look at an aerial applicator plane

[Cap'n Jack]

I didn't know that (at least) some of them used a turbine driven pump to deliver the cargo. I suppose it makes sense since the amount delivered is proportional to the plane's airspeed. I suppose if the pilot is flying a little fast, this system compensates by dropping more so the whole field is evenly covered. This was parked at Lincoln, NE.

 

[CJones]

I used to tell people that the little propeller under the belly was for when they had really heavy loads and needed a little extra power to get off the ground. You would be amazed at how many people just said "Oh." and went on their way before I had time to clue them in. hehe

As far as the pumps themselves go, some have adjustable pitch controls in the cockpit while others are ground adjustable. Some run constantly as long as their is sufficient air flow and others have electric brakes that allow start-and-stop the pump from the cockpit. If you have the 'always running' style pump and you lose one of the blades in flight, it apparently shakes the whole plane enough to make a pilot willing to land with a full load on a short strip rather than work through the vibration to lighten his load.

The flow is mostly controlled by either an electronically controlled inline valve or a manual valve controlled by the pilot. A certain boom pressure with a certain nozzle configuration yields a certain dropplet size and flow rate at a certain speed. The trick is balancing all of those variables while flying 10' off the deck at 140 mph dodging powerlines and making sure to not spray the wrong field.

 

[Cap'n Jack]

Chris, thanks for the additional information.

 

[jesse]

AFAIK they all have a propeller driven pump. My dad and grandpa once just finished rebuilding the engine on an A-9 Callair. My dad took it up for a test flight and after awhile got bored and started doing wing overs and whatever else. Suddenly there was a major vibration that shook the hell out of him. He shut the engine down and landed in a plowed field.

They spent the night looking over the engine and finally ripping apart the constant speed prop trying to figure out what went wrong. No dice One of them finally realized laying in bed that the damn spray pump's brake was letting loose and was the culprit behind the vibration.

 

[Cap'n Jack]

Thanks, Jesse- this was the first real close look I've been able to get of one of these planes. I would have liked to have inspected it more closely but the owner/pilot wasn't around.

 

[CJones]

Thanks, Jesse- this was the first real close look I've been able to get of one of these planes. I would have liked to have inspected it more closely but the owner/pilot wasn't around.

Be 'careful' when poking around cropdusters on the ramp - other than the nasty chemicals they are coated with, the FBI has a close eye on them. At least they did the last year I worked with them (about 3 years ago). We would get at least one and sometimes several phone calls per week from the FBI asking where our planes are located and if they are secure.

Oddly enough, though, when working at a middle-of-nowhere airport a few years ago, two middle-eastern guys approached me while I was loading a plane and asked if they could take photos of the cockpit. I said no b/c of all of the chemicals but that they could take pictures of the plane from a distance. Something just didn't seem 'right'.

 

[Henning]

AFAIK they all have a propeller driven pump. My dad and grandpa once just finished rebuilding the engine on an A-9 Callair. My dad took it up for a test flight and after awhile got bored and started doing wing overs and whatever else. Suddenly there was a major vibration that shook the hell out of him. He shut the engine down and landed in a plowed field.

They spent the night looking over the engine and finally ripping apart the constant speed prop trying to figure out what went wrong. No dice One of them finally realized laying in bed that the damn spray pump's brake was letting loose and was the culprit behind the vibration.

The Cessna 188 series use a hydraulic driven pump, outside of those though, you're pretty much correct.

 

[gprellwitz]

Be 'careful' when poking around cropdusters on the ramp - other than the nasty chemicals they are coated with, the FBI has a close eye on them. At least they did the last year I worked with them (about 3 years ago). We would get at least one and sometimes several phone calls per week from the FBI asking where our planes are located and if they are secure.

Oddly enough, though, when working at a middle-of-nowhere airport a few years ago, two middle-eastern guys approached me while I was loading a plane and asked if they could take photos of the cockpit. I said no b/c of all of the chemicals but that they could take pictures of the plane from a distance. Something just didn't seem 'right'.

Dang. I'm not typically paranoid, but that raises even my neck hairs!

 

[Cap'n Jack]

Be 'careful' when poking around cropdusters on the ramp - other than the nasty chemicals they are coated with, the FBI has a close eye on them. At least they did the last year I worked with them (about 3 years ago). We would get at least one and sometimes several phone calls per week from the FBI asking where our planes are located and if they are secure.

Oddly enough, though, when working at a middle-of-nowhere airport a few years ago, two middle-eastern guys approached me while I was loading a plane and asked if they could take photos of the cockpit. I said no b/c of all of the chemicals but that they could take pictures of the plane from a distance. Something just didn't seem 'right'.

I pretty much took my snaps and walked away pretty much for the reason you described. The TSA doesn't seem to come over to the GA side of KLNK and I don't want to give them a reason to have a presence there. We seem to have missed out on all the badge nonsense that exists at other class C airports- I think the commercial jets are too small.

 

[taters]

AFAIK they all have a propeller driven pump.

http://802u.com/ where is it on this one ?