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Best angle proceedure

'tis true...I've always settled on "about" and when I count out loud, figure it's a bit slower than an actual second.

Point is...it gives an approximation and that's a good starting point. I've flown over gravel bars and counted to 4 and flown away many times, thinking NOPE!!!

Steve
 
I can barely count to five. Guess that’s why a cub is about all I can fly worth a damn;-)
 
Getting better Performance with PSTOL flaps is just like VGs or most any other mod. If the pilot does not adapt his/her flying to the modification don't expect to see any noticeable change. I went 35 in Bushwheels last summer and I still have not figured them out completely. I know several pilots that have PSTOL flaps and they are not taking them off. But they said it took a lot of landings to figure out how to properly slow them down. Usually 3 MPH was what people feel they gained. The big draw that everybody loves is the improved visibility and ability to hit your spot. I don't think I have ever gotten myself into a strip that I would have to climb out of at 45 mph, everybody should know what how far off your airspeed is in slow flight and be able to adjust for it.
DENNY
 
Here is a good article on short field ops. Sadly, the images/graphs have expired, so only the text remains.

https://www.avweb.com/features/pelicans-perch-22short-and-soft-field-takeoffs-faa-vs-reality/

It has been stated in couple ways already, but may not be getting enough coverage: Best performance speeds depend a lot on how much performance you have. When weight and density altitude go up, performance goes down and it becomes very, very important to reduce drag if you want to climb. Nose high with lots of flaps is fun when light, low and cold (ignoring for the moment the problem of sudden power loss). It is a recipe for disaster when heavy, high and hot.
 
If the Super Cub stalls with full power and full flaps, it will snap to the left! A climb out at 45 with full power and full flaps is a dangerous maneuver! Try this at altitude...pull it up till it stalls...see what it does...not good at 100' AGL!
 
So far most of this discussion has centered on aircraft performance and speed related to Vx with or without flaps. Recognize that Vx is a function of Excess Thrust and Vy is a function of Excess Power. Everyone has concentrated on flaps and slats which impact L/D, very little has been said about propeller impacting the available thrust or the available power (they aren't the same). For each aircraft configuration (flap position, slats, CG, weight) there will be a specific L/D curve. In that configuration you will get the best performance at L/Dmax. The problem here is that at L/Dmax for a given configuration your propeller may not be providing maximum thrust so you either sacrifice a better L/D or available thrust. The only way to know what your best Vx is would be to go out and test each configuration to see what actually works. Then to throw a monkey wrench we could argue that a zoom climb might be better than a climb at Vx to clear those trees!
 
One thing Denny touched on, I'd expound on. My 35" AKB's, are safety equipment in my opinion...are as my Slats...so, my opinion has changed over time to realize that I still go most of the same old places I went with my Husky, or other less capable aircraft than my current ride...but I go these days with layers of better safety in the form of better equipment. I've only flown the Pistol flaps once and I liked them for all the stated reasons above.

The whole goal here...is to get to do what you like...again tomorrow, or next week. So try to do whatever you're doing safely and wisely!!


Steve.
 
f the Super Cub stalls with full power and full flaps, it will snap to the left! A climb out at 45 with full power and full flaps is a dangerous maneuver! Try this at altitude...pull it up till it stalls...see what it does...not good at 100' AGL!

My buddies bought a Cub from a guy who swore this would happen. I got the job of checking folks out in the beginning, and insisted that everyone see the deck angle and climb rate at full power full flaps just before stall, and that they then induce a stall. Not a big deal; the aircraft shudders, then stalls straight ahead. And this is an aircraft that could use a bit of wash-in adjustment. Heavy 160 Cub with VGs, weird wingtips, and flaps to the fuselage. Useful load 410#.

I also do it at flight review time.

Understand, if you start at level flight and yank it up into a stall, it indeed will snap. My advice - the Cub does not like snap maneuvers. I won’t even do snaps in my. Decathlon - I will do them in yours, if you want. With chutes.
 
Bob,
you're dead on...I was warned about this with the Husky...(it doesn't do it). I've been warned with the Supercub...(doesn't do it). Been warned about it in a bunch of high performance planes...(they don't do it). Yes, you can precipitate a wing drop...but with your feet keeping the ball in the middle ALL the way into the Stall...THEY DON'T JUST TUCK OVER AND SPIN!!!

Not in a SuperCub, Not in an RV-4 and not in the Pitts or Eagle...now that being said. Bad technique, and quit your feet flying (keeping the ball centered) and you can induce a spin. In all truth, it's a pretty extreme set of circumstances to make it happen.

I'm with you though...chutes, altitude it's good to see how extreme things really have to get, in order to cause a problem.

Steve
 
I've seen lots of airspeeds that show the plane is already flying (forward or backwards) when sitting on the ground. Needle pointed to anything but "0". Had folks tell me about and have experienced static leaks, static errors plumbed to cockpit, pitot leak downs, and all manner of low airspeed errors. The real STOL op: "My plane says it's still flying at 20!". If I expected to use a Vx departure I'd sure find out if my airspeed was worth looking at when climbing that slow.

Gary
 
BC12D-4-85 said:
I've seen lots of airspeeds that show the plane is already flying (forward or backwards) when sitting on the ground. Needle pointed to anything but "0". Had folks tell me about and have experienced static leaks, static errors plumbed to cockpit, pitot leak downs, and all manner of low airspeed errors. The real STOL op: "My plane says it's still flying at 20!". If I expected to use a Vx departure I'd sure find out if my airspeed was worth looking at when climbing that slow.

Gary
Click to expand...
Gary,
Thanks for bringing this up. I am about to start a mini test program so we can measure the effects of certain mods on a cub. Have you heard of a vaning pitot tube, that removes some of the errors from being at high angles of attack? Some folks said they have used them for flight test in the past but I haven't been able to track anything down .

Sent from my SM-G970U1 using Tapatalk
 
Maybe others like Skywagon will respond. Steve Pierce here has recently certified a prop. I assume the FAA had him install a better probe in front of the wing. At the least the front pitot opening might be reconfigured to an equivalent vertical slot? Or as you suggest ( I assume) a sealed pressure source that's vertically sensitive via sourcing into relative wind? There's lots of Internet ways to calibrate indicated airspeed via a pressure manometer made from looped tubing filled with liquid. Go search.

Gary
 
Vaning Pitot tubes have been used for years in flight testing. Boeing even uses one on a Helio Courier in Everett. You won't find much on the internet sadly, but all they are is about a 3 foot long probe, that has an axle slightly ahead of the center of balance, with a couple tail fins at the aft end and more of a bullet type nose extending clear of the wing area.

The vanes on the tail end, keep it aligned with the relative wind. the ones I have seen are pretty heavy duty, which I would assume is to keep flutter at bay...

Perhaps a better testing tool would be a towed array like Dick Johnson has utilized for Sailplane analysis...a drag rake, if you will...something you can extend out the window and retrieve upon completion of testing.

S.
 
This is an angle of attack boom. Notice the angle of the air flow in relation to the leading edge varies as much as two feet ahead of the wing. Notice also the yarn which is attached to the pitot tube. It is flowing straight aft. With the pitot installed in this location, that yarn flows the same at all speeds and angles of attack. This pitot was flight tested and calibrated at all speeds from stall to 150 mph. There were no errors at all speeds except below 35 mph where there appeared to be a 5 mph error. Since the yarn angle didn't change, I attribute that 5 mph to instrument error. At the low end, very few of the ASIs are accurate.

20210711_094512.jpg

If you wish to make one of these probes, make certain the pole is very stiff. This is the second one. The first (pvc pipe) wasn't as stiff and had an airspeed indicator mounted on it. It fluttered so bad, I thought it was going to break off.....at low speed.

On one twin engine STOL airplane which I flew a lot, I was able to hang it on the props with full flaps when lightly loaded and watch the airspeed needle actually move to a negative position of about 5 mph. It was shaking and vibrating a lot, but did not stall. This airplane did not have slats or Vgs. The airfoil was similar to the one Piper used.
 

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The Kid said:
My Pstol flaps say use the same figures that are in the super cub book for a normally flapped super cub according to AA. I haven't flown a lot of planes but the ones I have flown, other than the SC, say best angle is with partial flaps. SC says full flaps which is good from a landing standpoint and the whole basis of my question. Coming into land with full flaps on a one way short strip and an elk runs out in front of you. Either maybe hit the elk or try a "go around". So now the cub is already set up for VX. My question is "do I get maximum benefit at 45 mph indicted or do I literally hang it on the prop to clear those trees that forbid a go around and am below 45 mph indicated and if your tube isn't the same angle as mine, to the wing, they aren't going to read the same anyway? I was hoping the answer would be simple like, yes 45 or no just hang it on the prop. As I remember VX goes up with DA and VY comes dn? Then there is the weight of the aircraft. I think it's just simpler and safer to just hit the elk.
Click to expand...

We still havent really answered your question about hanging it on the prop or fly 45mph. I think thats because we dont really know. Piper tested 45 but its hard to know if they added margin to account for pilot variation. You would have to test and for sure it would be pilot technique and plane dependent.

I still stand by the best angle being achieved without flaps. Piper didnt break the laws of physics. Either that particular piper manual was in error or, more likely, it included assumptions that weren’t explicitly stated. It likely assumes you are doing a takeoff with an obstacle immediately at the end of the runway/gravel bar. In that case I would agree because full flaps would get you airborne earlier to start the climb. At some point, and likely not far from the point the plane is airborne, the clean plane’s flight path will overtake the flight path of the plane with full flaps. Curiously earlier version of the pa-18 manual shows Vx as 45 and clean. Also the cc-18-180 manual says 60mph clean is best angle. The cc-18 manual says thats at 2300 lbs and speed is lower for lower weights as expected. Just like you wouldnt extend flaps to increase your glide range, you wouldnt extend flaps to climb up and out of that box canyon. IMG_6658.JPGIMG_6660.JPG

Its also important to keep in mind that the procedures are written to accommodate pilots of all skill levels and not necessarily achieve the maximum capability of the airplane. For example retracting flaps at touchdown or popping flaps on takeoff definitely increase performance but there is a lot of risk with both maneuvers.


Sent from my iPhone using SuperCub.Org mobile app
 

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I have no idea whether there was any difference in testing requirements between CAR 3 and FAR 23, but the CC-18-180 is a Part 23 airplane. And they didn’t do any testing they didn’t have to…..example: Most production CC-18-180s were not certified for night or IFR.

MTV
 
BC12D-4-85 said:
Which is advisory versus mandatory: The Owner's Handbook (note the initial disclaimers), or the TCDS' required FAA approved Flight Manual? In my experience advice is worth considering, but like a**..... well you know the rest. What does the Approved FM say re the Vx procedure?

Gary
Click to expand...

Performance data such as Vx or Vy as well as all the data in performance graphs, are informational, not regulatory. Certainly if you hit that tree, and survived, an FAA Inspector or an NTSB Investigator might ask you what speed you used, and why, but I seriously doubt that choosing a different speed or configuration for Vx would precipitate a violation. Hitting the tree might.....

And, in these older designs, certificated prior to the standardized POH (which contain the AFM data), this information may be found in either or both the Owners Manual or the AFM.

MTV
 
Vx & Vy are determined as a result of performing a sawtooth climb flight test. These published numbers which are being discussed may just be the end result of Piper's testing. They are not regulatory and may not even be wise numbers to shoot for. They just happen to be the end result of the tests. Here's an article on performing the tests: https://www.kitplanes.com/sawtooth-climb-performance/
Learn the limits and best performance of your particular airplane by burning gasoline until you can wear it like a glove. Don't become fixated on a particular number on an airspeed indicator. Don't ask me what speeds I use, because I can't answer the question. What ever feels best at the time. I have had success with students who were having difficulties by completely covering the instrument panel. Miraculously, they had no more issues. They learned to fly with eyeballs, sound and feel.
 
For a very long time I agreed 100% with supercub83a's analysis. I think I could again agree, because I have seen the climb angle diagram many times in the past, and even used it a couple times.

One of my very smart friends (one of those guys with his name in the "who's who book of the National Academy of Sciences) convinced me that the Super Cub was a special case. However, he never showed me any math, or a modified climb angle diagram.

Most pilots are not scientists. A lot of pilots think flaps make you go up better. I think I shall re-join 83a's school of thought. Next time I do a Super Cub flight review we will study deck angles before stall for full power flaps up.
 
BC12D-4-85 said:
Which is advisory versus mandatory: The Owner's Handbook (note the initial disclaimers), or the TCDS' required FAA approved Flight Manual? In my experience advice is worth considering, but like a**..... well you know the rest. What does the Approved FM say re the Vx procedure?
Click to expand...

Dunno about the supercub, but the AFM for my Cessna 180 doesn't say anything about Vx or Vy.
It's mainly just the operating limitations, plus required instruments, G limits, CG range, etc.
I'm guessing the Piper AFM is similar.
 
The question that was raised here is whether or not to follow Piper's advice in the Owner's Manual, and perform Vx with full flaps at 45 IAS. The Flight Manual says nothing re Vx. As planes, engines, and instruments age is Piper's advice sound and safe for all pilots? Then, the OP adds PSTOL flaps to the combination and asks is it the same procedure?

Gary
 
Gary, I think it's always good to circle back to the root question...My opinion and solely that, is that full flap takeoffs do work, at times and not good practice at others. As pilots, we are the determining factor. My absolute best advice, would be to GO TEST YOURSELF and Your plane, and act accordingly.

I don't buy in that full flaps make a noticeable difference other than for a moment when you may not need to pop the tail quite as low to break ground. I can't speak for anyone else, but I have yanked my plane off the ground many times and accelerated away, raising flaps (mine are electric) for a variety of seemingly un-important reasons ( excess mud, bumps, cow crap, soft sand, wet...whatever...) and visibility over the nose, is...again, my opinion only...WAY more important.

I don't think Pipers advice, makes sense for all pilots, in all conditions and individuals planes. I do think Pipers advice might induce some pilots to think its normal operating procedure and that could be very bad, in certain cases.

As far as...Is Pipers advice sound and safe for all pilots??

Not Possible.


Steve
 
Frankly, the essential that one should take away from this discussion is the each of us needs to practice these kinds of performance maneuvers, in OUR airplane, at altitude, then conclude for ourselves if the recommendation of the manufacturer is safe and functional in THIS airplane.

Thus, if the situation arises where we are looking at trees in the top of our windshield, we won’t be playing test pilot.

As a flight instructor, I am often stunned to fly with someone in their plane, ask them to perform a simple maneuver, only to find out this is the first time they’ve stalled this plane…….seriously. I once flew in a brand new aircraft with a dealer. I told him I was going to stall the plane, when I did, the plane promptly got on its back. Dealer was having a cow “what did you do to my plane?”. I replied, okay YOU stall it. Same result. This guy had flown this brand new airplane half way across the country and around the backcountry, but had never stalled. The mechanics rigged it.

Whatever configuration and speed you decide you want to use, practice it, then calibrate your expectations appropriately when getting into tight places.

MTV
 
Bump: Next week I will get a chance to check angles in a 160 Super Cub. It is only slightly modified - Thrustline and Micro - but has mis-matched ailerons, which will put me on my back if I yank too hard. Cruise prop, which may make a difference.
I will mark the left window with lines at 30 and 45 degrees, with respect to the longeron under the window. I will be solo, but with full tanks. I promise to report back with flaps up climb angle. I will do the full flap climb as well, so I am comparing with the same airframe.

Climb angle - deck angle, really, is not the "up" path, since we are at roughly 14 degrees alpha flaps up (not sure what full flaps does to that, but probably significant).

I think it would be neat if another forumite would try the same thing. I will report back at the end of the month.
 
bob turner said:
Bump: Next week I will get a chance to check angles in a 160 Super Cub. It is only slightly modified - Thrustline and Micro - but has mis-matched ailerons, which will put me on my back if I yank too hard. Cruise prop, which may make a difference.
I will mark the left window with lines at 30 and 45 degrees, with respect to the longeron under the window. I will be solo, but with full tanks. I promise to report back with flaps up climb angle. I will do the full flap climb as well, so I am comparing with the same airframe.

Climb angle - deck angle, really, is not the "up" path, since we are at roughly 14 degrees alpha flaps up (not sure what full flaps does to that, but probably significant).

I think it would be neat if another forumite would try the same thing. I will report back at the end of the month.
Click to expand...

Actually, you can have a significant deck angle and not really going up much. I’m not sure deck angle means much when trying to climb over an obstacle.

MTV
 
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