APenNameAndThatA

5 hours ago, APenNameAndThatA said:

That is a good observation. The quoted heading is for the rhumb line between the two points, and it certainly looks a lot less that 303°

6 hours ago, Yenn said:

303 degrees seems a bit wrong to me.

The starting heading would be something less than 270 deg. and it would change as the flight progressed, I doubt that it would reach 303 deg even for the last leg.

I forgot. The bearing in the rocket box is magnetic. The OzR people promptly replied to an email I sent, and pointed that out to me. It changes with magnetic variation. So, even the rhumb line would be wavy if it was represented literally instread of symbolically!!!

51 minutes ago, Yenn said:

303 degrees seems a bit wrong to me.

The starting heading would be something less than 270 deg. and it would change as the flight progressed, I doubt that it would reach 303 deg even for the last leg.

That is a good observation. The quoted heading is for the rhumb line between the two points, and it certainly looks a lot less that 303°

The Distance to Go, and the Distance to Go (Great Circle) are stated as being the same. This is a screenshot from a trip I was planning from Brisbane to South Africa.

So, it looks like a draggy aircraft performs 10% worse and a really slippery aircraft performs 50% worse with the prop stopped vs idling. That makes sense, and is something for me to remember. Thank you for the info.

On 30/12/2020 at 10:44 AM, M61A1 said:

While I don't care too much for Boeing, this whole has been nothing more than a witch hunt, promoted by a heap of lawyers and people justifying their jobs, like many other "scandals" in current times.

It's about politics more than anything else.

The actions of the Ethiopian crew were inexcusable as the AD was released addressing the very issue  before it occurred. Finally when they got around to carrying out the correct actions and had it under control, they undid the corrective action.

It has nothing to do with what I "could have handled" and a lot to do with the fact that several other crews have experienced it and and it was a minor occurrence, including the previous crew  prior to the crash on the same aircraft.

Pretty much the whole emphasis on airline safety is organising it so that if the crew stuff up the plane still doesn't crash. The crew is dead, so they don't need to be excused. It is no coincidence that modern risk management began with airlines. The usual response after something goes wrong is to punish/sack/sue the person who did the wrong thing. With airlines, the person who would have been punished was already dead, so they needed a new procedure.

It is *inevitable* that pilots will make mistakes. At the moment, there are three fatal accidents per million departures. To have an accident rate that low means that systems have to have been in place to pilot errors. I head once that pilots make about 1.3 mistakes per flight. On a separate occasion, I heard a flying examiner say that they had never examined a pilot and found that they made no mistakes.

Blaming pilots is not how aviation safety works.

Don't get me started on Bowing. Bowing, and the 737 in particular, had a fantastic reputation. I'm not sure how long its going to take for them to get their reputation back, but I can say that my view of Mercedes Benz is still coloured by their period of bad quality in the early 1990's. F-ck you, Mercedes Benz.

31 minutes ago, old man emu said:

It stands to reason that if you stick a long, broad planks on the sides of a fuselage, it's going to take a lot of effort to push them over the top of the fuselage, so a slower roll rate. If you simply want to prevent too much roll if the aircraft is upset, then dihedral is the easiest thing to build in.

 

Wouldn't it be more useful in a fighter to have it somewhat unstable in the roll axis so that the aircraft would enter the manoeuvre a lot quicker? Trade off , trade off trade off.

Yes.

On 11/01/2021 at 12:33 PM, old man emu said:

T

 

Units should not be stated as part of formulas.

On 10/01/2021 at 11:39 AM, old man emu said:

That's 1920s - 30s expectation, when all engines - aircraft, motor vehicle and marine - were not as accurately made as they are now. The materials were not as good. The oils were not as good. the petrol was not as good and the ignition systems were not as good. And engines failed. Nowadays an engine failure still remains a 100% possability, but the probability could be thought to be well below 5%. Telling a student pilot to EXPECT and engine failure is scaremongering. Advise them that it could happen, but not that it must happen.The same goes for most things students are told will kill them - stall/spins at below 2000' AGL excepted.

The above conflates expectation with respect to preparation with expectation with respect to probability. The reason that it is important to expect an engine failure is as follows. It takes about three seconds for someone to respond to an engine failure on takeoff. During that time, the aircraft can go from Vy to below the stall speed. In addition, there is a temptation to pull the stick back. That means that the pilot needs to be ready to push the stick forward quickly.

About the probability of an engine failure being "well below 5%". Rotax engines have a failure rate of 15 per 100 000 hours. If you assume that flights are one hour long, and that *all* the failures are at takeoff, the probability of engine loss at takeoff is 0.015%.

I got some push back on this forum a while ago when I suggested that RA-Aus flying seemed to be safer motorcycle riding but more dangerous than driving. According to FlightSafety magazine, the former chief commissioner of the ATSB said that private pilots were dying at the same rate as motorcyclists. That means that RA-Aus flying is not a low-risk activity by normal measures.

All this means that there is genuine utility in pilots both expecting and engine failure on takeoff, and, at the same time, the same pilots knowing that an engine failure on takeoff is very unlikely.

3 hours ago, old man emu said:

Wouldn't small tails make lessen the aircraft's stability around the yawing axis, which would give better maneuverability is combat? 

 

Here's a quote from this research paper: https://www.fzt.haw-hamburg.de/pers/Scholz/Aero/AERO_TN_TailSizing_13-04-15.pdf

 

In the case of the tail, decreased stability would not help in maneuverability. It would decease ability to maintain co-ordinated flight with rapid turns. When maneuvering aircraft vigorously, rudder input is *increased*, so you need an effective rudder. It would not make adverse roll and Dutch roll worse. It would make the aircraft less stable, which would make it less useful as a gun platform.

This issue is different with dihedral, where stability acts against the ability to roll the aircraft.

The camo might be so that he is not spotted being where he is not supposed to be - rule breaking.

On 10/01/2021 at 4:56 PM, Garfly said:

I don't see any "hold my beer" type attitude in what we see here.  That trope evokes drunken idiots who are all ego and no skill.

 

I reckon if all pilots were required to attain that level of skill before they get a licence, then aviating, in general, would be a far safer proposition.

 

To me, this guy's in less danger of his engine failing in those valleys than we weekend-warriors are during any of our conventional departures.

 

(Precisely because we're clueless about low level manoeuvering.)

 

It is often said, here, that a lack of low-level training is a real problem in recreational flying. I'd agree, but maybe it's discouraged due to misplaced prejudice; its association with hooning.  Sure, there have been heaps of 'hold my beer' low level tragedies but that has nothing to do with what we see in this video.  Quite the opposite.  I'd be very surprised if this pilot ever spins in on base-to-final at a regular airport.

 

Contrary to the saying, "There are old pilots and bold pilots, but there are no old bold pilots," I think that there are skilled pilots who are bold. To my mind, this fellow is skilled AND he is deliberately flying in a way that challenges his skill, and is therefor putting him at risk. I didn't notice him pushing a rock out of the way, but I did notice the wind coming from the right wing push some branches out of the way.

I have not gone through the list of dangerous flying attitudes, but I do note that having a camouflage-coloured aircraft is consistent with a macho attitude. The bent-prop thing suggests that he does not think that it could never happen to him.

39 minutes ago, old man emu said:

I have now struck through the obviously offensive words in my original post in the hope that the discussion can now be centred on the theme of the thread, a discussion of whether or not knowing the mathematical description of lift generation is of greater value to the average pilot than learning by experience the simple fact that as the nose of an aircraft goes up beyond a certain angle, the wing is unable to produce sufficient to "Lift" cause the aircraft to be supported at a constant altitude?

 

And can we keep the discussion within the usual envelope of the majority of pilots who don't have teh need to cross the boundaries of the envelope of enjoying a flight?

 

Wrong *again*. There is no angle above which the nose goes which results in a stall. There is an angle of attack above which a stall will occur, but that is a different angle. 
 

And *again*. A wing does not have to be stalled to no longer be able to keep the aircraft at a constant altitude.  
 

And *again*. Your original post was about physics and now you are talking about maths. You can understand the basics of the physics without doing the maths. 
 

And *again*. When you make a post that is about two subjects, it is about two subjects. It’s not like you get to say silly things and then get to have them ignored. When you go around saying that a spirit level can do the same thing as an angle of attack meter, someone might believe you.
 

My guess is that it might have sunk in that you can’t use a spirit level on a stationary airplane to measure the optimum angle of attack, and that it might be sinking in that you can’t use a spirit level to measure angle of attack. So I suppose that’s a plus. 
 

But, hey, I can pick holes in other things. Technically, the *subject* of a thread is what the thread is about. The *theme* of a thread is what the thread ends up saying about the subject. For example, one subject of this thread is: discussion of whether or not... One of the themes of this thread is: nope,... 

J160 has lower max weight so I would have thought it would stall slower. Sure about the figures? I am NOT an expert on Jabirus. 

1 hour ago, old man emu said:

Not bizarre. The problem is with the inability of a certain person to think outside the box, or to have any experiences outside their restricted world.

 

This is what is commonly called a builder's spirit level This spirit level can be used to lay out lines in the vertical and horizontal planes as well as a line which is at 45 degrees to both the other two planes. Silly me assumed when I was talking about using a spirit (bubble)level that the reader would have had experience of using one. Obviously, in one case, I was wrong. Unfortunately, I initially chose the wrong item to illustrate what I meant by a bubble level. Consequently, I removed that image and replaced it with the image of something pilots would recognise. Unfortunately, I failed to remember that some people can only read the words and see the pictures, but cannot comprehend their deeper meaning.

 

So let's go into an explanation of how one would buy a slip indicator and apply it to be used as an AoA guide.

 

An aircraft has three planes of symmetry - vertical (yawing plane), longitudinal (roll) and lateral (pitch). A spirit level can be used to align the aircraft with reference to any one of these planes. For example, when taking measurements for the weight and balance of an aircraft, the longitudinal axis of the aircraft is aligned to the horizontal  and lateral planes. When an aircraft is aligned to those two planes, it should be in its straight and level configuration. At that time, a "slip indicator" can be fitted to the instrument panel aligned to the lateral plane. This is the usual way one of these devices is fitted and used.

 

However, a slip indicator can also be aligned to the longitudinal axis of the aircraft. In this configuration it becomes a "pitch" indicator. To turn it into an AoA indicator, the aircraft would be lifted by the tail until the chord line of the wing was aligned to the longitudinal plane (usually about 4 degrees nose down-tail up). Once that alignment was made, the slip indicator can be fitted to the aircraft so that the bubble is centralised. The aircraft is then returned so that the longitudinal axis is aligned with the horizontal plane. At this point the bubble should be off-centre by the same angle as the chord line is to the longitudinal axis of the aircraft. The position of the bubble can be marked on window of the indicator. This would indicate the position of the bubble when the aircraft was flying at the best AoA for Lift generation. The aircraft can then have the nose raised until the chord line of the wing is at 15-16 degrees above longitudinal plane. The location of the bubble is marked. That mark shows the position of the longitudinal axis of the aircraft when the wing will begin to stall.

 

So, does that clarify the use of a spirit level as a tool to monitor an aircraft's AoA ?

 

Can we now get back to the discussion of whether or not knowing the mathematical description of lift generation is of greater value to the average pilot than learning by experience the simple fact that as the nose of an aircraft goes up beyond a certain angle, the wing is unable to produce sufficient to "Lift" cause the aircraft to be supported at a constant altitude?

 

No. The best angle of attack will be whatever it is when the aircraft is at max weight and is flying at Vx or Vy. Most people would choose Vy as best, when total drag is at its least. This has nothing to do with the alignment of the airplane, although if the aircraft was designed well, they would coincide.

A spirit level cannot do the same thing as an angle of attack indicator because the the spirit level cannot take into account acceleration of the aircraft. If a spirit level was useful for determining angle of attack, the people would use them instead of a commercial angle of attack meter because they are far cheaper. 
 

Just to reiterate, the best angle of attack is at Vy, where drag is at its lowest. That’s how come Vy is published and airplanes don’t come fitted with slip indicators aligned with the aircraft.
 

The best angle of attack for lift generation is however much lift you need, up to a maximum, at about 14° angle of attack.   
 

The position on the spirit level will not show when the aircraft is about to stall as when an aircraft is about to stall, it will likely be accelerating and the spirit level will no longer be accurately reflecting the angle of attack. For example, if someone is recovering from a spiral dive, the aircraft could be 10° pitch up and have an angle of attack of 18° and be stalled. 
 

Likewise, if someone is climbing or descending, the slip indicator would not reflect angle of attack. Likewise, if the aircraft was speeding up or slowing down the slip indicator would not indicate the angle of attack. It would only reflect the angle of attack in straight and level flight where the aircraft was not speeding up or slowing down - not the time when aircraft stall. 
 

If you want to know when the aircraft is about to stall, you can mark a particular amount of control movement of the rudder (for a particular flap position).

4 hours ago, Jerry_Atrick said:

I think where OME may have originally wanted this thread to go is, is the theory syllabus for gaining the requisite flying qualification required to the extent it currently is:

 

etc.

 

The presentation of using a spirit level and a bank angle indicator, although worthy of discussion, narrowed the discussion somewhat  - although @old man emu - please correct if I am wrong.

 

In what way is discussing using a spirit level or a slip (not bank) indicator worthy of discussion about angle of attack? Particularly if said discussion says that they have anything to do with each other. As far as I can tell, OME *still* thinks that you can tell angle of attack with a slip indicator. Also, a slip indicator will not tell you your angle of bank, unless you are not turning. This is just bizarre.

2 hours ago, spacesailor said:

OME, thanks for your idea,s that spirit level is almost the same as old navigators used for taking star-site fixes..

I was questioning "stall" and angle of attack, surely it differs for greater speed over the wing.

Even F111,s don,t stall at maximum velocity when gaining altitude? .

I could be wrong. But all those rockets don,t seem to have a stall speed UNTILL spent.

spacesailor

The stall happens at the critical angle of attack (about 16 degrees) regardless of the velocity.

The spirit level won't show you the angle of attack. For example, if you are flying steadily nose up 20 degrees with a two degree angle of attack, the spirit level would show an angle of attack of about  20 degrees. If you were pulling out of a dive, with the aircraft level, the spirit level would probably show about a zero angle of attack, but you might be about to stall.

The idea of a spirit level showing angle of attack was so silly, I really thought you might be joking. I didn't comment about you saying you might "write a paper" because I thought that you would just say that you were joking. Looks like you weren't.

It seems to me that everyone else is too polite to explicitly correct you. It's not trolling if it stops someone from reading what you write and thinking it might be true, and it's not trolling if you learn that you cannot use a spirit level to determine angle of attack.

Experience is not the issue. Things like force and velocity vectors, and mass, force and acceleration are dealt with in high school maths and physics.

2 hours ago, old man emu said:

I was wondering how long it would take you to start flaming me, yet again. I'm sick of your trolling.

 

Once again you ignore the content of the discussion to incite trouble. You don't contribute in a meaningful way to any discussion of topics I post. And yet you are able to give a sensible response to Spacey.

 

So I used an unusual illustration. Too bad you don't have enough experience to recognise the type of spirit level it was. Just for you, I've replaced the image with something familiar. 

 

Now, if you can't make a sensible input into the discussion, why don't you jump in your widdle planet and see how long you can fly a course of 090T.

The spirit level won't show you the angle of attack.

1 minute ago, spacesailor said:

I Did say "near vertical " as I don,t think they did vertica takeoff.

But very steep up to target, then power off to turn downwards for another shot at their target, and glide back to base.

spacesailor

Okay. If you are flying near vertical, and the airplane is pointing in the same direction, OME's PAAM will show near 90 degrees. If you were flying a little inverted, say at 100 degrees pitch up, OME's patented angle of attack meter would indicate that you were flying a little backwards.

5 minutes ago, facthunter said:

Hanging in the harness straps upside down in a Tiger Moth didn't do much for me. Even though a canopy doesn't do much it's psychological. Later in life, speaking to  "other" pilots (as one does) I found I wasn't alone with that fear.. I'll be thinking of you tomorrow as I do an MRI and an ultrasound.

  Over the years, I've had a few passengers really suffering from fear of flying and the flighties would bring them up front and we'd try to look super relaxed, and that we wouldn't fly anything with something wrong with it because we wanted to spend our "super". (Joking) and the plane was (starting with B) the safest there is  and we are highly trained , cars are less safe. etc etc.. SOME really do suffer and I really feel for them.

 When I'm down the back, (hate it) and something like alpha floor goes off I just get a deep feeling of resignation  and dread and think "is this meathead going to be the way I go out after all  I've been through, and survived.?  THAT's NOT irrational fear. Nev

After I did the thrill rides with my eyes closed, I did them with my eyes open. Then, I did them without hanging on. That taught me to not be afraid to trust harnesses to hold me in place. That helped with aerobatic flight, where you have to have a soft touch on the controls and trust the harness to hold you in place.

16 minutes ago, spacesailor said:

Exerllent idea !.

BUT if the angle is near vertical, and your Big powerful motor, keeps your speed greater the the stall speed of said " rocket ",

Would you still stall ?.

German " Komet " rocket plane in mind.

spacesailor

 

If your airplane is flying straight up and pointing straight up, the angle of attack will be zero, and OME's patented angle of attack meter will show an angle of attack on 90 degrees.

You put the pic, and idea, of the bubble level as a joke, right?

A while ago, you posted a video about the Lindberg Reference. A while ago, the same person who produced the video posted that it was not necessary for a pilot to know about the theory of how an an aircraft works, and that a pilot only had to know that a particular inputs produced particular results.

7 hours ago, shafs64 said:

Hi.

 

Over the years I have struggled with my confidence as a pilot . And have not made the progress i would have wished somebody suggested a aerobatic flight a long time ago and i thought no way. but ten year later on the 4/1/21 they will be putting me and the phone pole i am holding onto in a aircraft with Colin Appleton.

 

Wish me luck. 

I wonder if you mean confidence or fear? I was too scared to do stalls. Did the scary rides at Dreamworld about 90 times. Then did a couple of aerobatic sessions in an Extra 300, including recovery from inverted spins. Problem solved. So, if the aerobatics is too scary to cope with, do the thrill rides and go back. Good luck. 

1 hour ago, spacesailor said:

SEE

Everything I was told in training was wrong !. LoL

spacesailor

We've all been there. I was told that in a stall it is okay to lower the nose and apply power at the same time. And I repeated that on this forum! (You have to lower the nose first, because adding power might pitch you up and yaw you to the left, which is not what you want to do if you are stalled close to the ground!)

17 hours ago, Yenn said:

The statement that the rudder does not turn the aircraft in co-ordinated flight sounds suss to me.

Set yourself up in a co-ordinated turn, which will mean using rudder to centre the ball. Then change the setting of the rudder. Do you not see a change of turn rate or bank angle?  If you do then something has caused that change and the only change you made was to rudder position.

The statement that elevator causes the turn is also suss. No matter what you do to the rudder in level flight it will not cause you to turn, unless you pull it so far back that you stall and spin.

What the elevator does is control your attitude, which is not necessarily the same as Angle of attack.

Angle of attack is a great concept, but most of us have no way of working out what it is at any time, but we can check our attitude so long as we are VFR.

If you are in a coordinated turn and then change the setting of the rudder, you see a change of turn rate - but you are no longer in a coordinated turn.

About the elevator not turning you in level flight: that's true, but you can't do a coordinated turn if you are in level flight.