When I was a kid my Dad’s plane rental operation had a couple -180s. When the FAR came in requiring a separate training program and endorsement for “complex” airplanes, we had to add a 28R-180 to the fleet to cover that need. Which did have a constant speed prop in addition to the retractable gear.
Wiki pretty well implied the answer, but I had to go photo hunting to be 100% sure.
Cheers.
The blue knob is the prop control then?
I had the privilege of flying the newer-style Cherokee Archer II a couple times this year. This one, to be specific. They call it a PA-28-181, actually, just to be different. No blue knobs in that one. I guess they put a 181-HP engine in it.
Okay, now that I have this thread open, it occurs to me to ask this:
Does anybody know where I can find a trove of W&B calculation practice problems to, y’know, practice with? I’m especially interested in glider-centric exercises, but not necessarily.
Are there any books with whole pages of exercise problems, like you would find in a typical Calculus textbook? Most of the books I see will have, e.g., just one fully worked-out W&B problem and maybe one more for the student to work out. I want something that more resembles a college Calculus textbook. Maybe I should write one myself.
Yes, although the color coding of black=throttle, blue=prop, & red=mixture, each with a differently shaped knob is a mid-late 1960s invention and took some years to flow through to all the manufacturers.
In case you didn’t notice, I’ll point out the knobs are designed in order of increasing discomfort to grasp. The throttle you use a lot is smooth, the prop knob you use some is partly bumpy, and the mixture that you touch only once in awhile and carefully at that is sharp & pointy.
In earlier eras on earlier types the three knobs may have been the identical shape & color. As were switches like gear and flap retraction. :eek:
Ergonomic design for error reduction is a surprisingly modern idea.
The Piper PA-28 Cherokee - Wikipedia shows that over the umpteen years the various incarnations of the Piper company have made the various incarnations of the baseline Cherokee design, the -180 or whatever suffix sorta corresponds to marketing horsepower except when it doesn’t. New and Improved for 1968! often requires a new dash number for marketing reasons even if the engine is the same.
I poked around a bunch online looking for sample problems. As you say there aren’t many.
This Weight and Balance has a real nice 1-page capsule summary of all a pilot needs to know.
Broadly, there are two ways GA aircraft present the data. One is to give you the arm/station value for each location, e.g. front seat occupants, fuel, luggage compartment, etc. That leaves you to do the multiplications spreadsheet style to figure out the moments.
For that style of problem it would be very easy to create an Excel spreadsheet that would generate problems using plausible random numbers and have you hand-calculate and enter the answers, then reveal its calculations for comparison.
The other style of data presentation is where the manufacturer gives you a graph with diagonal lines where you enter with the weight, go up or right to the diagonal line for whichever station, then go left or down to read off the corresponding moment. In effect the slope of that line *is *the arm.
Those would be much harder to create a generator for since most of the exercise is then in graph reading, not so much in arithmetic.
My overall take is W&B is hard if you (any you) is memorizing a rote recipe. There’s too many steps for that. But armed with a bigger picture understanding of what you’re trying to accomplish and why, it becomes simple multiply and add, multiply and add for at most a half-dozen pairs of numbers.
We were hiking on part of the AT, specifically at Pulpit Rock. I had my camera in hand, looking around, hoping to catch some of the soaring (birds - which I ended up getting at the next lookout, the Pinnacle). I look out & there is something soaring right towards us, a sailplane. He went close by, but not dangerously so. I did get some great shots of him, including a few that you can see the pilot looking at us. Obviously I can read the N-number & looked that up. I was able to find contact info for the owner, which from the photo was definitely the pilot. Would it be creepy & stalkerish to call him up & offer the mid-air shots or do you think it would be appreciated?
In the event of an emergency landing, is there any regs about how clear the runway needs to be? We did a balloon festival recently where we launched in the grass between the runway & taxiway. The airport was open to helicopters & emergencies only. They had cones out & an airport employee strictly monitoring that no one went on the runway (except for at least one flight were a few people holding crown lines were a few steps onto the runway). However, if a balloon is fully cold inflated or even still on the ground but already hot inflated it’s going to take 10 mins to get that down flat before we can walk away from it. One flight was light & variable winds which at about 150-160°, when the runway is 180°; it took a good 10-15 mins to get to the fence line on the far side.
Say it was a gear indicator so you’re not sure the plane will go straight upon touchdown. Must the grass be sterile? Will ATC clear the middle of the taxiway to prevent obstacles if the landing doesn’t go straight down the runway?
If it was me, I would appreciate being contacted and offered photos, but that’s me.
As for emergencies, once you’ve got a true emergency you are free to operate outside the regs to the extent necessary to stay safe. That said, the only emergency I can see requiring the use of an aerodrome that is effectively closed is one where it is simply not possible to land somewhere else, e.g., low fuel, fire, or failure of all engines. If one of those things had happened I’d expect ATC, if present, to do what they can to clear the airfield but the plane’s going to be landing there regardless. For something like a gear failure I’d be expecting the pilot to go and land at their intended destination.
Sailplane revenge porn! Post those pics where the whole world can see, and tell us where!!!
I estimate the probability at about 1.000 that he will be tickled pink to hear from you and see your pics. He was probably just showing off to you anyway. And they all know that their aircraft registration information is all over the web for anyone to see.
(ETA: If he lives anywhere near you, ask him to take you soaring with him. (Assuming he has, or can borrow, a two-place glider.) If all the stars align properly, there’s a high chance he will.)
Look up the YouTube videos by Bruno Vassel. He does things like that. If he’s soaring along a ridge and he sees hikers, he does loops in front of them. Here’s a video, if it’s the one I think it is, of him doing that, about 5 minutes long:
Glider Looping Near Mountain
Here’s another one, about 3½ hours long if you like watching this stuff:
Gliding Over Uinta Mountains - with loops for the hikers
When he sees a hiker encampment along a trail on a ridge, he likes to buzz them.
Yeah, this is the style of problem I need practice with. I’ve only had two available to work on: One practice problem from the book, and one real-life problem the instructor made me do before one of our lessons.
Note, by the way, that the whole computation is nothing more nor less than a plain old Sum-of-Products weighted-average computation — exactly the same sequence of steps you did when you were figuring your grade-point average. Then, if the CG turns out to be out-of-bounds, you have some extra steps to do, to figure out what adjustment you need to get the CG where you want it.
Here is the first shot I got of him; not quite dead on, but I was the first to spot him so it was, “Holy shit…INCOMING!”
Once we got to the Pinnacle, probably 45 min to an hour later there was a glider at elevation; too high to tell if it was still him or someone else. This is what I was hoping to get & why I had my camera out. The background is a little busy but it’s not every day one gets a good topside, closeup view of feathers.
From the balloon festival:
Sat PM flight. The near paving is the taxiway & the far one is the runway. If you look under the turquoise balloon (starting to lay down) you can see one person standing on the runway, one person taking pictures, & to the right, one person standing there just a step onto the grass. The balloons went out fairly low over the end of the runway. I certainly wouldn’t want to be any part of an emergency inbound at that moment.
Runway marker light @ sunrise, straight from the camera; unedited.
Since nobody at all has asked, I’ll just go ahead and weigh in here (heh) on W&B:
This is one of those chores that was meant for computers. It took 80 years or so, but we are now able to do W&B through automation, as god intended. I don’t say this lightly (heh, again!), I’m not usually someone who looks for technology to provide a quick fix, and very often I find a pencil and paper is the right tool for many tasks.
But not for this one.
Give me an app for this kind of thing any day. It’s one thing if you’re flying a small GA plane and not loading it to the gills. Especially a Piper, because their manuals use the graph method which is at least visual. But if you fly charter, as I do, and doing paperwork for every leg, goddam do I want it automated. Especially because, in this business, it’s always, “Oh hey, one more bag”, or “Oh hey, two more people”, or “Oh hey, one more bag, two more people, and can we change seats?” Ugh, iPad please?
I feel similarly about charts. Back when I first got into a Navajo we were using paper charts, and I remember thinking how stupid it was to unfold a huge enroute map that took up the entire cockpit to find a fix along an airway. Or dig through a book to find the approach plates. When iPads came into use for charts I thought, “Yes! This is how we should have been doing this all along. What the hell were we thinking these last decades?”
Like pilotage / ded reckoning flight plans, manual W&B calculations should be taught in training so pilots are aware of the underpinnings of the planning process. But after that, go to some reliable software.
End of rant. This was a heavy topic (heh!).
Since you’ve grokked the big picture that it’s just a weighted average, I’m not sure what more there is to practice.
Sure, you can always find a way to futz up multiplying 800# by 27.5". But I’m not sure how much you can practice that and get better at it. 40 years later I’m about as good at that as I was in high school and less good than I was in grade school. 
Ref Llama just above, I flew Navajos in Part 135 ops for a few months. We at least had a simple paper spreadsheet to fill out & a plain 4-banger calculator to do the multiplies & sums on. If I had to do one today by hand I’d start by making a paper grid of boxes for weights & arms then fill in the raw numbers, then whip out my phone’s 4-banger app. That’s using the equivalent of a 1990s supercomputer to emulate a 1980s cheapo giveaway calculator to make 4 and 5 digit basic arithmetic easier for a multi-trillion unit ultra-low-power-consumption parallel processor (me). What a silly world we live in.
Anyhow …
Ref my earlier post, it would not be hard to create an Excel spreadsheet that generated random plausible numbers for empty weights, front and rear seat occupants, fuel or ballast, etc., which you could work out on a homemade paper form to come to your answer. Then you scroll or flip or whatever to a different section of the Excel spreadsheet to see its W&B calculation starting from the same random inputs. If your answer matches its, you’re golden. If not you can compare your intermediate work vs its until you see where you went wrong. Then hit recalc to generate some new random data and do it again.
Lemme know if that’s more advanced Excel than you’re used to & I can probably whip something up in half & hour & send it to you.
Knew a guy who flew a Leastar 500, an old Hudson Bomber with R-2800’s on it. He had a mid-sized briefcase that had a diagram of the airplane and many dials. All seats, fuel tanks, oil tanks, etc…
Fuel quantity, oil quantity, # of pounds in each seat, cargo weight & location and it was all wheels, string and a total weight window and CG window. Just dial the numbers in and the total weight & CG position was right there. Never ever had a battery failure with this device. It was bigger than a handheld computer but this was before the HP43 was invented. I thought I could have used one on a lot of different aircraft I was flying at the time.
That was one cool little case. 
@Gus: Thanks for sharing that trip down your memory lane. That sounds like a really cool gizmo.
Now check this stuff out: Librascope weight and balance computer. But don’t click unless you’ve got a couple spare hours. You have been warned.
@Senegoid: I did find this generic W&B calculator: General Weight And Balance Demonstration Training Calculator
You could make up problems of your own using plausible weights and the arms for your relevant airplane(s), then work the problem yourself to get an answer. Then key the same info into this page to check your work. Having a Excel spreadsheet might be easier, but then you have to spend the effort to create the spreadsheet.
@LSLGuy: I just took a quick glance at that W&B calculator I linked. It’s noted there that it’s done in JavaScript.
I only need a much simpler version, just for gliders. If I wanted to get really ritzy, maybe I could include water ballast in the wings or tail.
It’s been 15 years since I took that Excel class. If I choose to do it that way, I could use the review. Or maybe I could try it with JavaScript. I’ve got a superficial bit of JS skill, probably enough to do a grade-point average or W&B script if I brush up on it a little bit.
(Actually, I’m using an old Linux system that comes with some of the OpenOffice apps, so if I try doing a spreadsheet I’d be working with that. I’ve also got Apache Web Server running locally so I can self-host little web sites to play with. Allegedly there’s some way I can make that available to the outside world, but I don’t know how to do that.)
I get parity errors every time I try that.
Just from a purely practical point of view, if you have a simple aircraft with few possible load variations, you can just do a W&B for some edge cases (heavy dude and bags in the back, light up front and vice versa) then just make sure you don’t exceed the known numbers. When I was doing commercial ops in a Pitts Special, I had a load sheet for me alone plus minimum fuel and another for me plus a 110 kg passenger and full fuel. Those two scenarios covered 99% of our flights. The CAA were quite practical and didn’t have a problem with it.
I like the idea of complicated setups that are only good for specific functions. Kind of the opposite of a tablet. A bit like a watch with lots of complications.
Edit: Just looked at LSLGuy’s link. That is some seriously cool kit!
I want one.
I like this thing too.
http://www.airwaysmuseum.com/EN%20ACC%201946%20Rodoniscope.htm
If you only have 4 factors (empty aircraft, front seat person, back seat person, & wing ballast) then you just use the first 4 lines of that web calculator. Leave all the other weights at zero and forget them. If you’re problem is real simple with just a single fixed sort of aircraft and one occupant, then just use the top 2 lines. There’s nothing magic about the names of what each line represents in their hypothetical aircraft; you could type any data on any row and get the same final answer.
The point being you can have a programming project or you can practice W&B. Both can be fun, but one may be mission creep vs. the other.
For sure I’ve often recommended the process of writing a program or a manual recipe as a way to cement student understanding or to get them to explore the corner cases of both the problem and of their understanding. It’s a variant of “you never know how well you *don’t *know your topic until you try to teach it.” For the folks who know how, programming is a form of teaching to an exceptionally dull but insanely persistent student. By the end of a quality programming project, you *do *know your problem space cold.
But you seem to have that pretty much cold already.