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Old 09-12-2017, 06:50 PM   #1
Mmalone442
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Default S2-B weights

So I'm new to the acro scene and have been doing all the training in a 8KCAB up to now. I have the opportunity to move into the S2-B soon and at 385$ a pop I've been trying to tackle all the numbers in the POH to show up prepared. Am I misreading the numbers or is the B designed for two skinny people? It appears with barely enough fuel for an hour, two guys weighing in at 190-200 a piece, (chutes, headsets,etc) would put it over the 1700LB gross weight. Then to get down to 1625Lbs for acro you would be down to 15 mins worth of gas.

The super D is almost impossible to get out of balance and with 1/2 tanks there's plenty of time to get to the practice area, spend 45 min or so and still have VFR reserves. I was just expecting bigger numbers for a Pitts I guess. I have my sights set on an S1-S but at 190LBS I may be to heavy! Maybe its off to Jenny craigs for me.


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Old 09-12-2017, 07:20 PM   #2
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I did my initial training in an S-2B in the Denver area. The instructor and I were both big guys 200+ lb with chutes and we always flew with a full tank of gas. I never asked about our weight but I suppose we might have been over gross for aerobatics. The plane absolutely hauled @SS compared to anything I'd flown up to that point. We never pulled more than 4g so even a bit over 1625 lb we probably never approached the structural limit of 1625 lb/6g.

190 lb should be fine for a S-1S. I've got 160 hrs in an S-1S at or above that weight. My plane was 840 lb empty.

Paul


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Old 09-12-2017, 08:02 PM   #3
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If you want one that will carry 2 fat ass guys and be under gross look at the Model 12.
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Old 09-12-2017, 08:38 PM   #4
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Sean, what was your fuel burn at cruise power with the 12?
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Old 09-12-2017, 10:02 PM   #5
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Quote:
Originally Posted by race38 View Post
Sean, what was your fuel burn at cruise power with the 12?
Depends on how fast you want to go. If I remember right the low cruise power setting for the M14 12gph.
http://www.jimkimballenterprises.com...ERSETTINGS.pdf
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Old 09-13-2017, 02:50 AM   #6
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Default Weight

Probably 90% of my flights in the B were under 4G so the G load is rarely an issue. The B just doesn't need high G loads even in contest flying.
Aerobatic gross weight x 6 divided by new gross weight equals new G limit. I flew with many heavy people in the B, in most cases in the front seat but occasionally in the back. One time with a lightweight trainee in the back seat I had to put some ballast in the baggage area the get the airplane to do a sustained flat spin.
Truth be told I don't think I ever did a weight and balance on the B. If the passengers butt fit between the longeron's we were good to go. With my S1S I knew exactly what my weight was for aerobatic flights as well as cross country.
The only thing the B will not tolerate is high speed snaps and gyro maneuvers. The lightweight props will take care of the crankshaft issues. I think the factory fix for the longeron's is just a band aid. Bottom line don't snap the B beyond the published limit speed.
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Old 09-13-2017, 01:19 PM   #7
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Thanks for the replies and input. I knew there had to be more to the story on such a great airplane.
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Old 09-13-2017, 02:02 PM   #8
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Hope you don't consider this jumping your thread, but a related question that I and the OP might also want the answer to:

Does the S2-A offer any greater wt/bal opportunity for 2-person aerobatic flying than the S2-B? Or is it less?

This website http://www.pittss2b.com/aviatbrochure.pdf lists the aerobatic gross weight for the S2-B at 1625, and sample empty weight of 1155, for an aerobatic useful load of 470.

But I couldn't get the answer for the S2-A. The S2-A type certificate (reprinted here http://www.pittss2b.com/a8sopitts.pdf) shows the aerobatic gross weight for the S2-A is 1500, but I couldn't find a sample empty weight for an S2-A online. Obviously the S2-A engine weighs less.

Last edited by red&black; 09-14-2017 at 01:51 AM.
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Old 09-13-2017, 07:09 PM   #9
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All I know is, if I ever design an airplane, I will not put a dash in the model name!!!!

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Old 09-13-2017, 07:26 PM   #10
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Good thought. The A is coming up at an acro wt of 1500lbs, 125 less than the B. I guess that is about the weight difference between the two engines. Slightly less fuel burn on the A so a little more time in the practice area. Both show a standard FAA 170lb pilot and pax in the AFM.
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Old 09-13-2017, 07:30 PM   #11
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This is what my S2Ae W&B looks like
ImageUploadedByBiplane Forum1505331041.881011.jpg
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Old 09-14-2017, 03:58 AM   #12
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Thanks for posting that info, S2e. So useful aerobatic load on your S2Ae is 453, which isn't all that different from useful load of 470 on the sample S2B above.

It's my understanding the S2-Ae is the kit built model of the S2-A from parts supplied by Aviat(?). I'm guessing the empty weights for factory built S2A's are in the same ballpark(?).

Last edited by red&black; 09-14-2017 at 04:08 AM.
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Old 09-14-2017, 08:45 AM   #13
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With a Hartzel and Concord battery, my empty weight was 1,070. I'm unsure what factory S2As weighed, but that should be close. (I have one of the later kits with tall gear and wide fuselage. Symmetrical ailerons)
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Old 09-15-2017, 12:03 AM   #14
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I have owned a S-2B for ten years and have put roughly 450 hours on her. I generally fly by myself and would say that I keep it below 5g's. The weight and balance thing is a grey area, lots of people have flown them over gross and out of CG and returned to the airport. As a Pitts 12 guy pointed out, you can do that but, eventually the cumulative strain might catch up with you. There are still very few examples of Pitts structural failure. I have done all sorts of spins and I don't find that the S-2B has any bad spin issues. I have messed up hammerheads and gyro maneuvers and found myself in strange territory, the Beggs, FART, and whatever technique works. Get the power off and figure out your yaw. Over the years I have noticed that Pitts accidents are usually a spin type event, with two people aboard, or a departure from the runway on landing, just a few weeks ago a S-2B crashed in Norway, a witness said that the airplane was doing aerobatic maneuvers and at one point "stopped flying" Spin? Two people on board. I think that out of CG is a bigger issue than over gross, you might try to depart with less fuel but that will already put you further aft CG, since the fuel tank is forward of the CG, as you burn off fuel your CG goes even further aft.


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