Safety (Lack of injury and death) is my prerequisite and priority

[SSCBD]

Jethro- as I stated earlier in this post the Partenavia p68 is one of the simplest twins around engine out to fly. However, you still need to rack up quite a few hours on single engine aircraft first before just jumping in to the deep end.

 

 

[Jethro Belle]

Jethro- as I stated earlier in this post the Partenavia p68 is one of the simplest twins around engine out to fly. However, you still need to rack up quite a few hours on single engine aircraft first before just jumping in to the deep end.

Yes I am sure you have known what I posted all along SSCBD. I wanted to correct the record to avoid perpetuating an error for others reading the thread. It will be quite a while before I get any aeroplane. Getting an inexpensive local plane to build some hours and fun is the way to go for me (hiring until then). For regular Bass Straight Crossing I may wait until I can afford flying a twin.

 

 

[Jethro Belle]

Turbs, People stopped hiring them out due over runs on landing and such. The early ones had struts (I think) the wings fail in twist when the aileron is involved excessively. They are a plane that actually gets you somewhere with a reasonable load. Nev

The original pre 1961 model was effectively a retractable undercarriage variant of the Cessna 182B. The wing was completely redesigned in 1961, so it wasn't simply a strengthened 182 wing with the strut removed. My understanding is that struts provide little stiffening against twist.

 

 

[facthunter]

I would agree with you on the strut. A single strut doesn't do much for twist. It's the high speed they descended at if you didn't watch it and people flinging/rolling them into a turn when too fast. Nev

 

 

[Jethro Belle]

Regarding props windmilling or stationary, a wind milling prop if it spun freely would not cause much drag until the RPM's got right up and the tips went supersonic.

Good morning Nev,

I have been pondering and researching what actually happens in various engine out scenarios, and conclude your statement that at first seemed correct to me is in fact incorrect. I don't want to cause any flame wars like appear on other forums. Please correct my humble input if it is wrong.

 

The following diagram indicates why a freewheeling (zero or very little resisting torque on the prop) would not reach sonic tip velocity. Note: In the drag creating condition shown at the bottom the propeller foil is generating lift inefficiently 'inverted', and would stall early.

 

 

source:Drag from a windmilling vs stationary prop - Page 3 - FLYER Forums post

 

The bottom diagram shows the negative lift (drag, hereafter denoted 'lift') condition of an auto-rotating propeller I referred to in my post #99. A supersonic tip velocity would be the top diagram and that would require power input. Thus a freewheeling propeller will actually auto-rotate slower than with power applied in excess to that required to overcome all mechanical friction (an idling engine may not provide excess power for a given airspeed, and posts indicating an idling engine on approach may actually contribute drag confirm this). As suggested in # 99 a freewheeling propeller will auto-rotate itself up to the optimal 'lift' speed (worst drag) and stay at that speed. To auto-rotate with 'lift' generating consequences requires the blade set at a small beta as the RecreationalFlying diagram shows. Feathered propellers or coarse pitch like boat propellers will not generate significant 'lift'.

 

If the prop is spinning and it is driving something that absorbs a lot of power (like a failed turbine) It has the ability to absorb multiples of the normal thrust figure because of the gearing and the torque of fast turning the dead engine and compressor as well as the ancillaries driven from the engine. For this reason turbo props pretty much universally have auto feather which acts almost instantly if the torque on the drive reduces. There is a sensor that triggers the auto-feather. but it's not active at low power settings.

If what I state above is correct it is the lack of drag that a turbine creates (based on posts I read and not what I thought which inline with what Nev stated) that allows the propeller to spin up to its "barn door" drag rotational speed. It is the drag that is directly consuming most energy, not mechanical friction in the propulsion system. This friction only consumes the component of 'lift' at right angles to the the aerodynamic drag it generates, and if it is excessive it will actually reduce the propeller drag down towards locked propeller drag magnitude as the rotational speed is reduced.

 

I think it is the belief that a freewheeling propeller spins up to ridiculously high speeds that muddies understanding. Also a Windmilling propeller is not the same as a freewheeling propeller.

 

I found the Canadians to be well informed and less argumentative in their forum (than others, not this forum) Windmilling or non-feathered propellers in flight. - AVCANADA. The papers I have read tend to confuse the basic idea with complexity, but do not contradict it.

 

I had read about turbo-prop pilots 'zeroing' their props to generate high drag. At zero beta the vector diagrams above don't hold (actually it would be the bottom one with the foil cord aligned with rotational direction and a high AoA). My understanding is that the turbines are still rotating the propellers. A zeroed prop would be fully stalled creating its stopped area drag, however the influence (the pressure field around a foil extends many cord lengths) is extended to the complete propeller disk area by rotating it at sufficiently high velocity. Since a auto-rotating foil operating inverted would have a coefficient of 'lift' little greater than one, the drag would be similar to that of an auto-rotating freewheeling propeller.

 

 

[Jethro Belle]

A single strut doesn't do much for twist.

Yes I did not think of the twin strut arrangement, but that was not on the C182 or pre1961 C210.

 

 

[turboplanner]

I would agree with you on the strut. A single strut doesn't do much for twist. It's the high speed they descended at if you didn't watch it and people flinging/rolling them into a turn when too fast. Nev

This is an easy one; no need to theorise. Just plug Cessna 210 into the ATSB search, and you’ll get the Australian accident history, including pilot induced flying into storms, turbulence etc.

 

 

[Jethro Belle]

Nobody has ( in my time of 50 years) died from an anything to do with flying, well at least at Gawler .

Your response left me thinking that crash comics only focus on what people have done wrong, rather than what has been done right.

Can you identify practices and circumstances in Gawler that has contributed to this good statistic. It seems like an active club with many members, so your result is meaningful. You have the Adelaide hills, even though it looks pretty flat at the Gawler Airport. If that is you base airport it looks like the Norther Expressway has chopped through your cross-strip and put a fence at the end of you main, so although it looks great it isn't inherently safe.

 

Do you fly safe aircraft makes? Good CFI? Low risk taking community? Good maintenance practices? Good weather? No home-builds?

 

Very interested in hearing your take on it. Do you know other clubs that could contribute their reasons for low crash statistics?

 

 

[facthunter]

I wasn't theorizing Turbs. I recall instances of them shedding a wing by being overloaded in twist, when they were new(er) and I know people who have hired them out and now don't do it for the reason you stated. I don't mind the aeroplane, but it does have some landing gear extend/ retract issues. (probably maintenance related) and you have to plan ahead to slow it up. Like ANY clean plane. If you fly it as you should all is fine. NO plane is safe in a thunderstorm.. Avoid them. Nev

 

 

[turboplanner]

I wasn't theorizing Turbs. I recall instances of them shedding a wing by being overloaded in twist, when they were new(er) and I know people who have hired them out and now don't do it for the reason you stated. I don't mind the aeroplane, but it does have some landing gear extend/ retract issues. (probably maintenance related) and you have to plan ahead to slow it up. Like ANY clean plane. If you fly it as you should all is fine. NO plane is safe in a thunderstorm.. Avoid them. Nev

I wasn't theorizing Turbs. I recall instances of them shedding a wing by being overloaded in twist, when they were new(er) and I know people who have hired them out and now don't do it for the reason you stated. I don't mind the aeroplane, but it does have some landing gear extend/ retract issues. (probably maintenance related) and you have to plan ahead to slow it up. Like ANY clean plane. If you fly it as you should all is fine. NO plane is safe in a thunderstorm.. Avoid them. Nev

I understand; Just trying to make a point to save Jethro researching the 210 engineering. For a combination of Bass Strait and a learner pilot, I’d rule the 210 out.

 

 

[Jethro Belle]

I can understand your first line; if you aren't worried about it you don't feel any apprehension, and after all you can see the coast or the edge of the forest out there the horizon, and then I started reading "The Killing Zone and realized I had become an idiot, and realized it was so easy to extend my life.

While looking up where I can get "The Killing Zone" I encountered comments questioning the statistics quoted (eg:

 

[MEDIA=reddit]flying/comments/3eni9i[/MEDIA]) The FAA was prompted to publish 'correct' statistics https://www.faa.gov/data_research/research/med_humanfacs/oamtechreports/2010s/media/201503.pdf . Interesting reading, with the peak annualized non-IR GA accident rates peaking at 250 TFH and 823 TFH for IR. I always imagined it would drop off sort of linearly after the first few hours of going solo. Shows the importance of mission difficulty and misplaced confidence in determining outcomes.

 

 

[Jethro Belle]

For a combination of Bass Strait and a learner pilot, I’d rule the 210 out.

I will not attempt a Bass Straight crossing until considering myself past probationary pilot status, in any aircraft. From my previous post that will need at least 250 hrs under my belt to have 'improving' judgement.

 

This thread convinced me a few pages back: now I am just picking up pearls of wisdom and theory. Being from an Engineering background I am interested in the C210 in its own right. My dream was never about flying that type of aeroplane, but the same phsysics apply. .

 

 

[facthunter]

It's quicker and would have a very good glide angle with prop feathered and clean Gear up etc. It's probably academic. You are unlikely to be able to hire one easily. It has a weird characteristic with the gear retraction. Due to the incredible way it happens you have a lot more drag DURING the retract cycle than with the gear left down.. It's a very strange action. Quite clever but if it was really good they wouldn't have discontinued it.. IF you could devote a bit of time and cash to get one and have it in great condition it is quite economical per pax Km. You would spend time and money to get well trained. (Is there any other way?) and not get much use out of the training. If I was doing the Tassie Run, I would hire a Duchess and make sure there's no icing likely. They are a simple enough twin. Not pretty or exotic. Nev

 

 

[Jethro Belle]

It's quicker and would have a very good glide angle with prop feathered and clean Gear up etc. It's probably academic. You are unlikely to be able to hire one easily. It has a weird characteristic with the gear retraction. Due to the incredible way it happens you have a lot more drag DURING the retract cycle than with the gear left down.. It's a very strange action. Quite clever but if it was really good they wouldn't have discontinued it.. IF you could devote a bit of time and cash to get one and have it in great condition it is quite economical per pax Km. You would spend time and money to get well trained. (Is there any other way?) and not get much use out of the training. If I was doing the Tassie Run, I would hire a Duchess and make sure there's no icing likely. They are a simple enough twin. Not pretty or exotic. Nev

Yes, I remember the Cessna Cutlass (It has wing struts too ). Describes the arrangement well. First time I saw it (about 10 years old) I thought the undercarriage was falling off. I agree it is a clever design (but manufacturing quality and details seem to have caused their bad reputation, not the basic design). Service reports backed reasons are give in Cessna 172RG Cutlass RG - AVweb Features Article . Nothing that could not have been rectified, but any complex mechanical system has more modes of failure, including ability to land 'gear up'. The only 'designed in' problems I can see are that failure to lock in place will end up with wheels pulling back and collapsing, and the rearward weight-shift.

 

I have two very young children, so a 'family bus' is one option, but avoiding risk to children is why my plans are long term and for very low risk compared to other posters. I need to stay alive long past my "use by" date for their sake. I would like a 'fast' plane and observe birds fly with their gear up, but realize the higher landing speeds and difficulty that come with it, especially transiting from a drag bucket (also lower crash survivability, not bush landing ...)

 

I read about the Duchess while researching engine out characteristics. It was highly regarded as a 'safe' twin to suffer an engine failure. Very nice, but above my resources. Definitely a hire or share aircraft

 

 

[facthunter]

ALL high wing Cessna's had very effective "fowler" flaps that give slow good vis approaches but sap power and cause a large trim change when power is applied. I think most "authorities" have locked out the last stage of flap in their infinite wisdom.. There are stol modifications for most Cessna wings. They are one of the best "hot and high" (high density altitude) wings there are for getting out of short, rough strips,. where a tailwheel could be considered but the Nosewheel works but may require some maintenance. Stone chips on the oleo etc I don't think the strutless versions go that much faster. You would think they would. Nev

 

 

[Jethro Belle]

I don't think the strutless versions go that much faster. You would think they would. Nev

Yes, it does seem counter-intuitive . Same goes for retractable undercarriage. I have concluded that if the basic aircraft is a drag bucket (and most older GA I place in that category from an engineering/fluid dynamic perspective) the removal of struts and undercarriage has less effect than linear thinking hopes. Power required goes up with velocity cubed, so reducing overall drag 10% will shift cruise speed upwards only 2.15% max, but the increased weight means it is less than that.

 

Birds fly without crutches and their gear up, so we are not designing aeroplanes that clean yet. The trick is to start with slippery fuselage and low drag wings, or not bother. Slippery aircraft also mean less fuel burn.

 

Slippery aircraft should IMHO have airbrakes/spoilers fitted like gliders. More complexity and pilot skill required, but so much extra control on landing. You could fly much higher approaches and not float/overrun. (All IMHO and expect correction if pilots of both glides and GA can shed light)

 

I am sure everyone here knows it already.

 

 

[facthunter]

A lot changes once you push the above 150 knot area. Fixed U/C's are not really part of that envelope or bi planes. Flutter becomes a problem and the plane must be overall clean and well designed You get used to differential spoilers and roll rate improvement. using them easily enough but the cost is high so probably confined to jets. Nev

 

 

[Jethro Belle]

Flutter becomes a problem

That is what scares the bejeezus out of me with home build, and even some factory builds. Static G wing loads tests don't come close. I wouldn't want to be the 'test-pilot' testing Vne on such aircraft and is a major reason I would not design my own, unless there was significant reasons to do so. Impossible to build an infinitely stiff wing, and several circumstances can cause flutter. How strong the wing you test is does not necessarily mean all builds will be identical, unless you have very tight build control.

 

A good time to have a BRS, so long as it doesn't go with the wing, or get twisted in the spiral dive.

 

150 knots is around the Vne of the Sonerai which was what a starting point for me, and still have not rulled out. You can upgrade it to 185 knots Vne which is safely higher than I would ever expect to reach in worst circumstances for my non-aerobatic flying.

 

 

[crashley]

Yes, it does seem counter-intuitive . Same goes for retractable undercarriage. I have concluded that if the basic aircraft is a drag bucket (and most older GA I place in that category from an engineering/fluid dynamic perspective) the removal of struts and undercarriage has less effect than linear thinking hopes. Power required goes up with velocity cubed, so reducing overall drag 10% will shift cruise speed upwards only 2.15% max, but the increased weight means it is less than that.Birds fly without crutches and their gear up, so we are not designing aeroplanes that clean yet. The trick is to start with slippery fuselage and low drag wings, or not bother. Slippery aircraft also mean less fuel burn.

 

Slippery aircraft should IMHO have airbrakes/spoilers fitted like gliders. More complexity and pilot skill required, but so much extra control on landing. You could fly much higher approaches and not float/overrun. (All IMHO and expect correction if pilots of both glides and GA can shed light)

 

I am sure everyone here knows it already.

what a lot of rot I hope people participating in this thread are not serious

 

it started out bad and has got to the stage that I cant ignore it any more

 

There has been a few good comments but it is getting overboard now

 

to suggest that all slippery aircraft have airbrakes and spoilers just so you can have better control on landing is just ludicrous

 

and the comments about flying to tassie well it is less than 100 miles to tassie from yarram so less generally less than an hours flying do people really believe that there engine fly for an hour without failing

 

 

[turboplanner]

and the comments about flying to tassie well it is less than 100 miles to tassie from yarram so less generally less than an hours flying do people really believe that there engine fly for an hour without failing

Yes it is, but the engine isn't going to tell you before departure that it's going to fail,.

However, weather and communications are far more important.

 

His initial prerequisite (must) was no loss of life hence the early recommendations.

 

 

[SSCBD]

Crashley - an engine can fail any time, anywhere whatever you fly , and usually at the worst point - its just a matter of time.

 

However I find the thread as you state a lot of rot as well.

 

If Jethro wants to fly across to and from Tassie its his choice - but he must understand the risks of flying or get another hobby. Spend the money to get experience and /or get a twin when you have enough hours under your belt, for his comfort of his single engine anxiety.

 

A lot of paperwork will be involved if you hit the drink.

 

 

[Jethro Belle]

There has been a few good comments but it is getting overboard now

to suggest that all slippery aircraft have air-brakes and spoilers just so you can have better control on landing is just ludicrous

 

I will take that as a 'correction', as I requested for my humble non-expert opinion.

 

I meant nice, rather than should . That is the problem with thinking out loud.

 

Does anyone think having a way to wash of speed (other than side slipping) provides more landing options and control? It was a long time ago, so I may not be recalling correctly, but some KR2s were fitted with a flap under the fuselage to act as an air-brake.

 

I am not criticizing any 'slippery' planes for not having such things fitted as they add weight, complexity and additional failure modes. There seems to be continuing mentions about how pilots (not you @crashley) have difficulty avoiding not floating, overshooting etc. Obviously pilots transitioning from 'drag buckets' are in mind, but I have heard glider pilots make comments similar to mine.

 

Maybe I should qualify that by slippery I meant GA with high stall speeds (not LSA). Your RV12 looks efficient and pretty slippery, but it has RAA stall speed, so not much speed to 'wash off'. I was not meaning to imply RV12s and such must have them fitted. Such devices are probably of little use for most members.

 

PS: Yes I know: gliders generate lift more efficiently so some way of loosing it is a must.

[turboplanner]

Does anyone think having a way to wash of speed (other than side slipping) provides more landing options and control? /QUOTE]You have half your flight to wash off speed if you really need it, or you can pick a distance out slow down to gear speed, put the gear down, slow down to flap stage speed, put some flap down and you have all of Downwind, all of Base, all of Final to the round out, and even some of the strip length to slow down. Quite a choice for even the most slippery aircraft. If you get a good instructor, he will show you where to be and at what speed in the circuit, so that, from your Base turn you will not need to make anymore adjustments to touch down. He usually won't show you how he does that, but that's the optimum to aim for. If you're talking about being too high on final, that's another discussion.

[facthunter]

Be impossible to land an efficient glider without spoilers.( DRAG enhancers). Having them for roll control is another giant step. (differential action). It is in theory much better than ailerons (or wing warping) but complex and they can float. Nev

 

 

[turboplanner]

Be impossible to land an efficient glider without spoilers.( DRAG enhancers). Having them for roll control is another giant step. (differential action). It is in theory much better than ailerons (or wing warping) but complex and they can float. Nev

Where did that come from? An eagle can just turn his feathers.

You were an instructor, how would you train a student who was coming in too fast in his Sonnerai?