Umm, calculate performance much?

poadeleted21

poadeleted21

Touchdown! Greaser!
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Aug 18, 2011
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my understanding is there is nothing to calculate with most ag planes. there really isn't an official max gross. its whatever you're willing to go with.
 
There are a lot of eyeball calculations being made in that type of flying. "Give me 1" of fuel", "Fill the hopper to about the top row of rivets", "Make sure not to fill me past the BOTTOM of the cross-member in the hopper - not the TOP of the cross-member" (btw - the cross-member was a 1" stainless steel tube, so 1" made *that* much difference - really). I have personally been told all of those things when loading ag planes.

That retardant must be some really heavy stuff. I've seen an AT802 take off of 2300' grass with a slight incline with full (300+gallon) fuel, and full (790ish gallon) hopper. Of course, this was just at the crack of dawn, so DA was low, and he had a valley he dropped off into after getting to the end of the runway, but he did clear the powerlines across the road from the end of the runway.
 
tonycondon said:
my understanding is there is nothing to calculate with most ag planes. there really isn't an official max gross. its whatever you're willing to go with.
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We have an official max gross on our 1965 model PA-25 (Pawnee), but we don't have any runway required or climb performance data.

It's hard to believe that a modern AirTractor would not have Max GW limits or some type of takeoff data.
 
BillTIZ said:
We have an official max gross on our 1965 model PA-25 (Pawnee), but we don't have any runway required or climb performance data.

It's hard to believe that a modern AirTractor would not have Max GW limits or some type of takeoff data.
Click to expand...

hmm I would have figured that would be required reading info, I see the folks in question were only 80% full we're not THAT high IIRC about a 4000' long rwy at 3600' elevation or so, a HIGH DA is 7000', I can guess withing 100' of where I'm going to break ground in my PA28 given my loading situation, I guess the loads are drastically different though.
 
bartmc said:
Maybe this is status quo for air tractor drivers?
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It's apparently more widespread than that. I have it on pretty good authority that FAA enforcement is beginning to look more closely at W&B violations (and the related performance hits).
 
bartmc said:
Maybe I'm being hard on them but twice this week airtractors have had to dump their load to keep from smashing into a small hill at the end of the runway. I've got 60 or so T/O at this airport in all sorts of conditions, they must have been REALLY HEAVY. The hill is a non issue, supposedly. Maybe this is status quo for air tractor drivers?

http://missoulian.com/news/state-and-regional/article_341752f4-d448-11e0-a07c-001cc4c002e0.html
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Look, they need to get out of there with as much load as they can, sometimes they go over. It's retardant, not pesticide. This stuff isn't hurting anything. If he can't fly out, he dumps 75 lbs off and goes. Big deal, now he is flying with his maximum load he can haul to the fire that trip. Better than taking not enough and wasting time and fuel at a fire.

This is Utility work. Hell, at least with fire bombing you have the option to shed weight quickly. This isn't a big deal.
 
Henning said:
Look, they need to get out of there with as much load as they can, sometimes they go over. It's retardant, not pesticide. This stuff isn't hurting anything. If he can't fly out, he dumps 75 lbs off and goes. Big deal, now he is flying with his maximum load he can haul to the fire that trip. Better than taking not enough and wasting time and fuel at a fire.

This is Utility work. Hell, at least with fire bombing you have the option to shed weight quickly. This isn't a big deal.
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I was treading lightly and not accusing because I thought this might be the case. One thing is for sure, they got a bigger set of them than I do.
 
bartmc said:
hmm I would have figured that would be required reading info, I see the folks in question were only 80% full we're not THAT high IIRC about a 4000' long rwy at 3600' elevation or so, a HIGH DA is 7000', I can guess withing 100' of where I'm going to break ground in my PA28 given my loading situation, I guess the loads are drastically different though.
Click to expand...

We have AirTractor or Dromadary single engine turbine fire bombers out here. They use every inch of 4500ft runway at 2800 MSL on 90F+ days. Luckily we are out in the flat of the valley with no trees or poles around.

Our 1965 250HP Pawnee is "Restricted" category with no data other than MaxGW and what is required to compute CG. Things were a lot different in 1965.
 
BillTIZ said:
We have an official max gross on our 1965 model PA-25 (Pawnee), but we don't have any runway required or climb performance data.

It's hard to believe that a modern AirTractor would not have Max GW limits or some type of takeoff data.
Click to expand...


In Restricted Category, Manufacturers GW isn't really binding. The planes I was flying had gross weight upgrades penned into the logbooks by pilots, and they were legal.
 
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