Vx, Vy, and turnbacks

[Russ]

Blong...........why the "funny".....???

 

nothing funny about getting a "picture" in ones mind that at xxxx height, i can achieve xxx site, at xxx speed........i don't think "funny" is warranted, but that's just me. Grrrrrrr

 

 

[facthunter]

To take up Russ's point on cooling, when you fly at minimum speeds with full power the engine temps will rise fast. Not only do you have less forward speed to force air through the cowling, the angle of the intake openings and undercowl exit become less effective, due to the higher angle of attack (relative airflow.) Nev

 

 

[Head in the clouds]

I don't think overheating was Russ's concern, I think he is asking about shock cooling of the engine caused by reducing power to flight idle.

 

Certainly air-cooled engines don't like rapid power reduction and it can have bad consequences for the cylinder heads in particular. Lycomings and Continentals tend to have cracking issues between the valve seat inserts when those engines are frequently reduced to low power, skydiving ops without CS props comes to mind.

 

That is one of the benefits of liquid cooled heads such as Subaru and Rotax 912/4, it prevents shock cooling and the engines can be idled for long periods even in a cool climate.

 

I think the best idea might be to ask Jabiru themselves for their opinion. If there's nothing forthcoming from them I would suggest cooling the engine down gradually by reducing power progressively and keeping an eye on the CHT to see that it doesn't drop off too quickly. Once you're established idle gliding and temps have stabilised again it should be OK to idle for an extended period while you conduct your exercise. Bringing the power up again should be done progressively too.

 

 

[Russ]

thanks hic ( headincloud).......that's exactly what i'm chasing.......shoving throttle to idle, and gliding at idle

 

 

[facthunter]

Well from say 5,000 feet with colder air your motor will be quite cold in the areas that have lots of fins It's about 5 minutes to ground level from that height . Cowl gills can help prevent that and reduce cooling drag in other situations where full airflow is not required. Smaller motors don't have quite the problem bigger ones do with cracking but it's still undesirable. Piston clearances at colder temps are excessive. A two stroke with premix doesn't get much oil on closed throttle either. Most careful operators do a descent with some power still on and use the potential energy to fly a bit faster and save a bit of time. Vne permitting Nev

 

 

[Ada Elle]

Hi there Ada Elle, what is your profession and back ground ? You come across as being very clinical and analytical .I think Head in the Clouds may be someone you can learn from.

When I first started in spent too much time worrying about what was happening below the windscreen rather than looking through it.

I'm a medico - so clinical pretty much sums me up.

 

I wonder where I can find a flight instructor with a physics degree.

 

 

[Geoff13]

I'm a medico - so clinical pretty much sums me up.I wonder where I can find a flight instructor with a physics degree.

I would be more interested in finding one with experience rather than pieces of paper.

 

 

[Ada Elle]

I would be more interested in finding one with experience rather than pieces of paper.

That's how you get people who don't understand aerodynamics teaching people how to fly.

 

 

[djpacro]

That's how you get people who don't understand aerodynamics teaching people how to fly.

How about experience as a flight instructor plus experience having worked as an aerodynamicist?I don't have high regard for a physicist regarding aerodynamics of aircraft.

And, it really doesn't need a high level of knowledge of aerodynamics to be a good flight instructor.

 

 

[facthunter]

Instructors don't need to be able to design aeroplanes to be a good instructor. Also experience doesn't ensure you are a good instructor but you have to have enough across a varied base and be a competent and confident pilot . (It might surprise some that a few instructors and senior pilots are not that basically confident and you notice this at times.). Most importantly you must be able to impart the skills and knowledge effectively. I have done tertiary studies and taught physics and use it a lot in my flying but that doesn't suit everybody. Not all students have done much of it but they can get past with a solid elementary knowledge of basic Newtonian Physics. It strikes me that you personally may like more explanation than many do. That is OK if you can find the right source but don't over complicate matters. Understand but get your priorities right. Nev

 

 

[Ada Elle]

I'm really grateful for my flight instructors who have given me excellent instruction that has probably saved my life at least once. I'm currently doing tailwheel conversion with someone who is extraordinarily experienced. but if I want to ask questions like these, it's hard to find instructors that give can give me a why with an explanation detailed enough.

 

 

[kgwilson]

Just had a read through all this & there is a lot of good information posted. Personally when the fan stops on climb out I am not going to work out the mathematics of what is the best option because I don't have the time. I'm going to land straight ahead or thereabouts unless I have at least 1000 feet above take off or it is straight into giant redwoods or something similar.

 

Every time will be different depending on wind speed, direction, temperature, altitude AMSL, QNH/pressure, aircraft load & type & a bunch of other factors including human ones. I am also going to fly the aircraft at its best performance/maintenance factor as has been indicated by others. I practice engine failures along with many ( should be all) other pilots but it never really prepares you 100% for the real event.

 

 

[poteroo]

I'm a medico - so clinical pretty much sums me up.I wonder where I can find a flight instructor with a physics degree.

40 year career as an agric scientist. My flying specs are on this site. happy days,

 

 

[Guest Andys@coffs]

Its well and good to talk about what happens when the fan stops, but the original question was about putting yourself in the best position prior to that happening. Ive been in a for real EFATO and I never in the seconds I had before I was landing across the cross strip glanced at the ASI once, but equally before the failure it was just another normal takeoff, one which after the event I identified a couple of things I could have done better and lifted my chances of success. The main fault was that I did an intersection departure so didn't have the option to land ahead where if I'd started the roll from the runway threshold I probably would have had that opportunity. It wasn't a true EFATO in that Id just turned crosswind so the impossible turn was only half of the real "impossible turn" but was still impossible with the height I had available at the time in that I couldn't dog leg back onto the main runway, I was still offset to the side.....

 

I'll bet that an intersection departure has a much greater affect on your height than determining which of Vx or Vy is the most appropriate....use all that is provided, that which is in front is potentially usable, that which is behind to all intents and purposes may as well simply not exist.

 

 

[Aldo]

Re-posted from where I had it yesterday

 

The trouble with over educated people is they over complicate things, I have seriously intelligent engineers work for me but have to teach them what to do to get the results I need, if I left them to their own devices all I would have is 10,000 pages of calculations and nothing I could sell to anyone.

 

I'm really grateful for my flight instructors who have given me excellent instruction

Ada

 

Just listen to what your instructors tell you, follow the rules and listen to good information passed on by people with lots of experience and you will have a long and enjoyable flying career/hobby. You don't need to know the in's and out's of a rats backside to be a very competent and capable pilot.

 

By all means if aerodynamics is what turns your crank go study it to your hearts content but stick time will count ten fold when the noise up the front stops.

 

Aldo

 

 

[Aldo]

Re-posted from where I had it yesterday

 

The trouble with over educated people is they over complicate things, I have seriously intelligent engineers work for me but have to teach them what to do to get the results I need, if I left them to their own devices all I would have is 10,000 pages of calculations and nothing I could sell to anyone.

 

I'm really grateful for my flight instructors who have given me excellent instruction

Ada

 

Just listen to what your instructors tell you, follow the rules and listen to good information passed on by people with lots of experience and you will have a long and enjoyable flying career/hobby. You don't need to know the in's and out's of a rats backside to be a very competent and capable pilot.

 

By all means if aerodynamics is what turns your crank go study it to your hearts content but stick time will count ten fold when the noise up the front stops.

 

Aldo

 

 

[ayavner]

if aerodynamics is what turns your crank

I think you'll find its internal combustion...

 

 

[ayavner]

if aerodynamics is what turns your crank

I think you'll find its internal combustion...

 

 

[facthunter]

Even humans are internal combustion. Training of the right kind is what makes the day in aviation The element of management is far more critical than driving a car or riding a bike. Instinctive reactions play less of a part. Preparation, Planning and prioritising in an emergency or abnormal situation feature high on the list of must do's. Often the disaster takes time to develop and is the cumulative effect of a number of bad decisions or events or lack of awareness. You are remote from help and master of the vessel, no matter what the size of the plane. Nev

 

 

[facthunter]

Even humans are internal combustion. Training of the right kind is what makes the day in aviation The element of management is far more critical than driving a car or riding a bike. Instinctive reactions play less of a part. Preparation, Planning and prioritising in an emergency or abnormal situation feature high on the list of must do's. Often the disaster takes time to develop and is the cumulative effect of a number of bad decisions or events or lack of awareness. You are remote from help and master of the vessel, no matter what the size of the plane. Nev

 

 

[diesel]

I remember a mathmatician trying to put formular to turbulence as he flew. Awfull pilot.chas

 

 

[diesel]

I remember a mathmatician trying to put formular to turbulence as he flew. Awfull pilot.chas

 

 

[Gnarly Gnu]

Hey don't knock mathematicians, it's a useful piloting skill for navigation in particular. I wonder how many folk fiddle with the whiz wheel or poke at the GPS without knowing much about how the numbers are arrived at.

 

 

[Gnarly Gnu]

Hey don't knock mathematicians, it's a useful piloting skill for navigation in particular. I wonder how many folk fiddle with the whiz wheel or poke at the GPS without knowing much about how the numbers are arrived at.

 

 

[Ada Elle]

The trouble with over educated people is they over complicate things, I have seriously intelligent engineers work for me but have to teach them what to do to get the results I need, if I left them to their own devices all I would have is 10,000 pages of calculations and nothing I could sell to anyone.Just listen to what your instructors tell you, follow the rules and listen to good information passed on by people with lots of experience and you will have a long and enjoyable flying career/hobby. You don't need to know the in's and out's of a rats backside to be a very competent and capable pilot.

By all means if aerodynamics is what turns your crank go study it to your hearts content but stick time will count ten fold when the noise up the front stops.

Over-educated pretty much describes me.

 

I'm sure that a lot of people in Sydney will know who my ab initio instructor if I say that the first page of my logbook consists of hundreds of circuits, almost all glide approaches. This was good for me - it turned me into a safe pilot - but not into a confident pilot. I was scared of steep turns, of incipient spins, of flying out of balance more than a ball's width. Add to that three years away from flying, and when I came back to flying I was a very nervous pilot, with my head in the cockpit - flying speeds, and watching the AI, etc.

 

Gliding, and doing some proper spins/unusual attitudes and discovering just how hard it is to spin a lot of aircraft, has given me more confidence in flying nearer to the edges of the envelope. But it's also led me to realise that lots of instructors have been teaching time honoured techniques without necessarily understanding the basic sciences and why. In my day job I love thinking about how to translate basic science knowledge into understanding what is going on with the patient, and I've been blessed with many good teachers who both know their basic anatomy and physiology really well, as well as having good technical and patient skills. But I can't expect flight instructors to be surgical professors!