djpacro

One of the gems is Cessna's booklet which was published back in the '70s to counter misinformation about spinning. About time that it was promoted again. https://mikeklochcfi.files.wordpress.com/2018/03/cessna-spin-manual.pdf It has much general information (obviously a lot of information speciific to the Cessna so be careful about generalising) too with information such as: "For the purpose of this discussion, we will divide the spin into three distinct phases. ..... Here, in the entry phase, recovery from or prevention of the spin is as simple as normal stall recovery since, in fact, at this point that's all we are really faced with. .... During this incipient phase, spin recoveries in those airplanes approved for intentional spins are usually rapid, and, in some airplanes, may occur merely by relaxing the pro-spin rudder and elevator deflec- tions. However, positive spin recovery control inputs should be used regardless of the phase of the spin during which recovery is initiated. .... Due to the attitude of the airplane in a spin the total motion is made up of roiling and usually pitching motions as well as the predominate yawing motions. Movement of the airplane flight controls affects the rate of motion about one of the axes. Because of the strong gyroscopic influences in the spin, improper aerodynamic control inputs can have an adverse affect on the spin motion. .... Some of the additional factors which have (or may have) an effect on spin behavior and spin recovery characteristics are aircraft loading (distribution, center of gravity and weight), altitude, power, and rigging. Distribution of the weight of the airplane can have a significant effect on spin behavior. The addition of weight at any distance from the center of gravity of the airplane will increase its moment of inertia about two axes. This increased inertia independent of the center of gravity location or weight will tend to promote a less steep spin attitude and more sluggish recoveries. Forward location of the c. g. will usually make it more diffi- cult to obtain a pure spin due to the reduced elevator effectiveness." I mentioned that effect of moment of inertia in another thread. Pilots get to determine weight and CG but, as Cessna stated above, the increased moment of inertia is independent of weight and CG. eg fuel in outboard wing tanks vs inboard wing tanks. However, we usually deal with small changes in weight and CG associated with a large change in moment of inertia. Pilots have been be caught out with small ballast weights added near the tail to adjust CG with no consideration given to the moment arm squared and the big increase in moment of inertia. What some pilots (or the accident investigators) have observed to be the result of a small CG change was actually caused by a change in moment of inertia. NB: the USA FAA supported this booklet with their bulletin to all flight instructors back then.

A spin resistance standard was added to the FAR 23 airworthiness design and testing requirements in 1991. The Columbia 300 was certified to this standard in 1998. It carries clear warnings in the POH "Do not attempt to spin the airplane under any circumstances ..... During the flight test phase of the airplane's certification, spins were not performed. It is not known if the airplane will recover from a spin." The Cirrus was certified with an Equivalent Level of Safety by having the CAPS. Perhaps considered to have a spin resistant wing design as they followed some guidance from NASA with this. Anyway, the Cirrus spin certification and some spin testing done for EASA is a longer story for perhaps another day as it is slightly off topic.

Spin resistant does not mean that it won't spin nor that, if it does, it will recover. A spin about 2 minutes into this video. Just because it recovered from this spin does not mean that it will recover from other spin modes. J

"The way in which the mass of an airplane is distributed between the wing and fuselage is the most important single factor in spinning because it determines the way in which the airplane, while spinning, responds to control movements, especially to elevators and ailerons. An airplane rotating in a spin can be considered to be a large gyroscope. Since there are mass and angular rotation about all three axes, inertia moments are produced about all three axes." Fig 3 shows the balance of pitching moments in a spin which basically determines the angle of attack in the fully developed spin. The nose down aerodynamic moments vs the nose up moments from inertia. Worth repeating NASA's statement: "The way in which the mass of an airplane is distributed between the wing and fuselage is the most important single factor in spinning ..." NASA is not referring to CG there but to the moments of inertia. "In order for the airplane to recover from the spin, the equilibrium must be broken, and this is normally accomplished by changing the aerodynamic moment by moving a control or combination of controls that can cause the greatest antispin moment. ....... The loading of the airplane dictates the control movements required for recovery. ..... Deflection of the rudder to oppose the spinning rotation directly is always recommended, but in many cases, it is not adequate to provide recovery. For the wing-heavy loadings, down elevator is the primary recovery control." "Three factors are of almost overriding importance with regard to spin and recovery characteristics: (a) The relative distribution of the mass of the airplane between the wing and fuselage, which is commonly expressed in terms of the inertia yawing-moment parameter, a nondimensional factor relating the rolling and pitching moments of inertia (b) The tail configuration, which must provide damping for the spinning rotation and the rudder power for recovery and which is commonly evaluated in terms of an empirically determined tail-damping power factor (c) The density of the airplane relative to the density of the air, which is commonly expressed in terms of the relative-density factor" We don't need to concern ourselves with effects of air density so just moments of inertia and tail design. Some aircraft types have weak nose down pitching moments so the nose up inertia moments drive them towards a much higher angle of attack in the spin. NASA has shown this for the Grumman AA-1

CASA's Part 61 MOS requires this as essential knowledge for all pilots: "Differentiate between a spin and a spiral dive in a light aeroplane and describe the standard recovery technique for each manoeuvre." Yet I regularly encounter pilots and students who do not know the "standard" recovery technique for a spin. Worse, I regularly encounter flight instructors and trainee flight instructors who also do not know the correct recovery technique - either that "standard" one or, more importantly, the one described in the flight manual of the type they fly. They are required to have a spin flight activity endorsement so a greater underpinning knowledge and competency. Recently, a flight examiner failed two flight instructor candidates on the ground component of their test because they described dangerously incorrect spin recovery technique in their theory briefing. CASA helped recently with their AC 61-16 Spin avoidance and stall recovery training The FAA's Airplane Flying Handbook, Chapter 5: Maintaining Aircraft Control: Upset Prevention and Recovery Training has excellent information. To go a bit deeper into the subject for much of the underpinning knowledge required by CASA for a spin endorsement I suggest starting with NASA TN D-6575 SUMMARY OF SPIN TECHNOLOGY AS RELATED TO LIGHT I GENERAL-AVIATION AIRPLANES by James Bowman (I worked with Jim for a while). It is engineering stuff however fairly light reading.

Not really, moment of inertia is simply a property of mass and geometry of the aeroplane. My statement was: "I can get the usually docile Decathlon to snap into a spin with little warning and be in an established, flattening spin extremely quickly ..." yes, with power and aileron - typical scenario for an unintentional spin. I wasn't referring to the normal practice spins with power off and neutral aileron. There is more that I'd like to discuss so I will commence another thread for this.

There are differences between the variants of the 172. Does any variant state "difficult to control"? At the start of the autorotation. Autorotation results in a nose up pitching moment - the greater the moments of inertia (as you stated) the greater the nose up pitcnhing moment. Yes, pilots are familiar with the need to hold pro-spin controls for their practice spins. Easy to recover like that in the early part of an incipient spin. Doesn't always happen like the usual practice spin. I can get the usually docile Decathlon to snap into a spin with little warning and be in an established, flattening spin extremely quickly - no chance of recovery by closing the throttle and centralising the controls. I would be very surprised to see the USA organisation take much of an interest.

Nothing to do with the accident, just a general comment after reading some posts here. From CASA’s Part 61 MOS for an RPL, required knowledge is: ”Differentiate between a spin and a spiral dive in a light aeroplane and describe the standard recovery technique from each.” A flight examiner told me recently that he failed two new flight instructor candidates because their preprepared briefing to him incorrectly described the spin recovery method. They obviously hadn’t bothered to look at the relevant section of the POH for the aeroplane they were flying. Nor had they taken any notice of the cockpit placard on spin recovery. They had accepted what they picked up from someone else. In my opinion one of the the best (and free) references as a source of that Part 61 MOS knowledge requirement is https://www.faa.gov/sites/faa.gov/files/regulations_policies/handbooks_manuals/aviation/airplane_handbook/06_afh_ch5.pdf

Seems to me that some would benefit by reading CASA’s AC on EFBs especially the explanation on airworthiness regulations for mounting them

I used a universal camera tube mount for my SkyEcho, worked well doing aerobatics. Now have a Garmin GTX335 transponder with ADSB out combined with a uAvionix Ping USB. Works very well.

Endurance of 5.5 hrs is 17.3 litres/hour. Quite sporting for a 150 hp Lycoming. That is much more than Pazmany claims - maximum of 4.1 hrs but only with the 108 hp Lycoming 0-235 engine fitted.

The Aviat Husky has a modified Clark Y, it works well. One of my favourites is the NACA 4412. However, at least as important as the aerofoil is the wing planform and washout etc. NASA CR-1646 A DESIGN SUMMARY OF STALL CHARACTERISTICS OF STRAIGHT WING AIRCRAFT https://ntrs.nasa.gov/api/citations/19710021678/downloads/19710021678.pdf

When Wamira was cancelled and the govt bought the PC-9 ... Well ... the Wamira story partly answers your question ... it started off as a good idea but then the RAAF kept gold-plating the specifications for their basic trainer such that the weight and cost just blew out. Of course, the PC-9 came nowhere near meeting their specs ... and it wasn't even a basic trainer - the technical selection was made by RAAF officers with nil experience at flight training. Industry knew the cost was going to blow out but just continued to play the game, earn money, as it didn't matter to them whether the project was successful or not. By the end the project had a single, nearly complete prototype at the cost where the govt expected 72 production aircraft would've been delivered. Nil risk to industry in just spending money and not having to test a prototype and produce a finished product. As part of the PC-9 deal, Australian industry was offered participation in the PC-12 program. I saw lots of analysis and PowerPoint slides showing that the PC-12 would never be viable.

The story in the video seems to have come from https://tamamshud.blogspot.com/2016/05/somerton-man-explosive-details-from_15.html This story of the Avon Sabre is also relevant https://www.key.aero/article/creating-australian-sabre Chief Engineer Ian Ring and some of the other engineers were still working at CAC into the '70s. https://www.australianflying.com.au/news/warbirds-the-turbo-interceptor-boomerang I went to a presentation by Ian Ring on all the CAC designs.

1. When doing that stuff is when full control deflection is used .... so pilots must know the associated limitations. Some obviously don't eg https://aviation-safety.net/wikibase/39811 2. As you know, G limits are generally much less in the nose down direction (negative G) so full down elevator, at an airspeed where full up elevator would not cause the positive G limit to be exceeded, will cause those negative G limits to be exceeded. Some notes on this at https://www.aviationsafetymagazine.com/airmanship/the-yellow-arc/ There is NOT a separate Va for negative Gs and the FAA didn't see it necessary to come up with a different Vo for negative Gs. eg https://www.atsb.gov.au/media/news-items/2020/flight-control-confusion

Mick is eminently sensible and an excellent businessman.

From the FAA's AC on light aircraft certification. AC23-19. "The design maneuvering speed is a value chosen by the applicant. It may not be less than Vs√ n and need not be greater than Vc, but it could be greater if the applicant chose the higher value. The loads resulting from full control surface deflections at VA are used to design the empennage and ailerons in part 23, §§ 23.423, 23.441, and 23.455." That is an important point - the engineering purpose of VA is to design the tail and the ailerons - NOT the wing! "VA should not be interpreted as a speed that would permit the pilot unrestricted flight-control movement without exceeding airplane structural limits, nor should it be interpreted as a gust penetration speed." Pilots - please note this. "Only if VA = Vs √n will the airplane stall in a nose-up pitching maneuver at, or near, limit load factor. For airplanes where VA>VS√n, the pilot would have to check the maneuver; otherwise the airplane would exceed the limit load factor.” Yep, what a surprise to pilots, VA can be more than VS√n ! Do the arithmetic on the airplane that you fly to check what you have. Don't forget to use CAS. "Amendment 23-45 added the operating maneuvering speed, VO, in § 23.1507. VO is established not greater than VS√n, and it is a speed where the airplane will stall in a nose-up pitching maneuver before exceeding the airplane structural limits." Yep, but you will only see that in new airplanes designed recently.

https://www.faa.gov/documentlibrary/media/advisory_circular/ac_43.13-1b_w-chg1.pdf

It attracted a little bit of interest when the first one appeared but …. only 3 as of 2015 indicates its relevance. My last recollection of anything about it was a fatal accident involving a well-known pilot some years ago.

Some pics from my visit to the CallAir Museum in 2013. Glen Call was my guide.

It isn’t as bad as it looks! http://aussieadsb.com/airspaces Just take the time to identify what is relevant and the lower altitude of each section of restricted area. Easier on weekends. This is old but the general explanation may help http://redcliffeaeroclub.com.au/files/AMB12nov15.pdf More info here https://www.casa.gov.au/search-centre/stay-ontrack-flying-gold-coast-region/general-military-information#RAconditionalstatuslegend Give RAAF a call at your planning stage, they will appreciate it https://www.airservicesaustralia.com/wp-content/uploads/VCA-Hotspot-Amberley-flyer.pdf I recently flew Melbourne to Watts Bridge and return. That leg was Gunnedah to Watts Bridge, however on quite a few previous trips I have stopped at Moree. Fairly straightforward from Watts Bridge part of the world to Caboolture however a busy area.

I don't believe any have come from the factory like that. After the great crew moment arm debacle https://www.bristell.com/wp-content/uploads/2022/12/BRM-Safety-Alert-001_2020_R2.pdf Prior to that the POH had a loading example with two people of my weight shown to be within the aft limit. The revised POH omits that example as we'd be way behind the aft limit. I wonder if they checked the strength of the engine mounting.

https://www.casa.gov.au/search-centre/manuals-and-handbooks/designated-aviation-medical-examiners-handbook/44-special-reports-and-periodic-tests-required-medical-certification#Designatedaviationmedicalexaminer'sreferencecharts states that “private pilots, if clinically indicated” so there must be a particular need for them to have required the tests - perhaps just the fact that you do one every two years or perhaps those test results indicated a clinical need. 116% heart rate? CASA requires 100% or 145 bpm for your age. It is counterproductive to try to impress them with any more - coast along at 100% so the results are better? I went to a Vic Aviation Medicine seminar some years ago where a CASA speaker said that they’d rather have someone die on a treadmill than in an airplane. Lots of info around on this subject, my advice is do all you can to improve the test results and ask your DAME to verify the need.

A hard landing does not result from landing with a tailwind. Same as engine stoppage (say, from carb icing, per another ATSB report) does not result in a fatal accident. That ATSB report also noted the stall/spin and the pilot's prior history of flying very close to the stall in the circuit on landing approach. Proper training is warranted. Incidentally, that modification is very complex for a retrofit.