Airplane purchasing equation!

[glafaille]

I've been searching for an airplane to purchase for 5 months and I think I have it all figured out!

Airplane buying simplified!

x= Price of aircraft
y= Estimated value of avionics
z= Hours remaining till overhaul
r= TT of aircraft
t= Bladders installed
a= Vref valuation
b= Years since new paint and interior
N= Any other considerations not listed above

Suitability of aircraft for my mission at my price = N/(x+y+z+t)a^b+(z*r)b^a

As the equation approaches 1, the probability aircraft will meet my needs is 0.

 

[carusoam]

It always helps when you know exactly

- what you want

- what you can live with

- what you can't live without

- what that is worth to you (your price is not always theirs, but when it is...)

- where you are going to get its PPI done.  (Not everything passes a PPI)

- where the cash is, in hand or ability to get the loan through. Insurance ready to go.

- how you are going to get the plane home.

- what transition training you are going to do.

- what it costs to rent somebody else's plane.

- what the cost of misery is because you don't have your plane.

 

buying a plane is easier the second time around.

Best regards,

-a-

[glafaille]

I'll need to add those to the equation!

[jlunseth]

9 hours ago, carusoam said:

 

- what the cost of misery is because you don't have your plane.

Ain't that the truth.  I always get depressed when my plane is away for the annual, which it is right now.  I might not even fly it if it were home, but I would have the choice, and not having the choice is what is depressing.

Edited March 17, 2016 by jlunseth

[1964-M20E]

Look at the amount of money you have for the airplane double it and add 25% then you will have what you need for the first couple of years.

 

After that just put fuel in it and go and do not worry about money as long as you can pay the hangar rent.

 

 

[aviatoreb]

23 hours ago, glafaille said:

I've been searching for an airplane to purchase for 5 months and I think I have it all figured out!

Airplane buying simplified!

x= Price of aircraft
y= Estimated value of avionics
z= Hours remaining till overhaul
r= TT of aircraft
t= Bladders installed
a= Vref valuation
b= Years since new paint and interior
N= Any other considerations not listed above

Suitability of aircraft for my mission at my price = N/(x+y+z+t)a^b+(z*r)b^a

As the equation approaches 1, the probability aircraft will meet my needs is 0.

 

I have two questions.

1) is that a^b in the denominator?

2) Are all the parameters positive unbounded real valued numbers?  It seems as if t and N may be booleans. Maybe a could be negative?  But if a is negative then a^b may be complex valued.  Also if a is negative and the airplane was painted this year so b=0, then the second term in the equation would be undefined.  I am worried there is a problem with the equation.  Likewise you must require the constraint that x+y+z+t>0, and since I see no reason that y must be positive then it is not clear to me that this constraint will always be true.

[Hank]

Erik--why would you want to allow for both/either the value of the complete aircraft (a) or the installed avionics (b) to be less than zero? I've never seen something that I could be paid to take away, with the exception of other people's garbage. We are discussing airplanes here, not the contents of someone's trash can, although I admit the value can be much lower than the seller anticipates--that's why there are terms for Asking Price (x) and Valuation (a).

As for your concerns about recent repaint and undefined terms, I always thought X^0 = 1, and 0^X = 0. I also thought the equation should have been handwritten as N divided by everything else (silly ithingy doesn't have "divided by" symbol!), or written on a single line with parentheses as 

           Suitability = N/[(x+y+z+t)a^b+(z*r)b^a]

Similarly, I see no reason for your proposed "x+y+z+t>0" constraint, but I would support that x, y & r must each be > 0. It looks like t is binary, either t=0 for my wet wings or t=1 for someone else's bladders. Z could be anything, but it is difficult to pinpoint as some people are forced to overhaul well before TBO while others fly 20-30% or more beyond it with no condition issues. Maybe z should be redefined as "z = hours remaining to TBO" to allow for the real variation seen in overhaul times?

The difficult part then becomes assigning a value to N . . . . .

[drapo]

Since aircaft ownership isn't logical, why would you try to justify it with an equation?

Glafaille, stop trying to make sense of all this, take the plunge and enjoy the good, the bad and the ugly of Mooney ownership!

[Andy95W]

 N/(x+y+z+t)a^b+(z*r)b^a = all of your available money

[M20F]

I never understood the reason for imaginary numbers in school till I became a plane owner...

[steingar]

For me the most salient thing was that the Mooney owner wanted to trade for my airplane.  Would have had to have been a deathtrap not to go for that.

[bonal]

Glafaille, stop trying to make sense of all this, take the plunge and enjoy the good, the bad and the ugly of Mooney ownership

Agreed, if you try to approach very vintage aircraft purchase from an anal retentive point of view you will have a very long search. I based my purchase on a complete lack of anything smart, Took some doing but we are now enjoying a real nice airplane. And the last thing I think about is resale value I bought it to fly it. If we move up in performance we'll get what the market bears. Owning a private airplane makes zero financial sense because the joy of flying your own airplane is priceless.

[PMcClure]

When I bought my Mooney, I went about it a little different. I decided what I wanted - an Ovation, with less than 10 years on the air frame, without G1000, with 530WAAS, and with King autopilot and Air conditioning, in excellent condition with no history of damage or excuses. I also had an approximate budget. Then I set out to find the best deal I could find. In nearly 6 months, I found only a few planes that met the parameters but had to rule out most due to big issues - no log books, damage history, run out engine, deferred maintenance, etc.... At the end of the day, I only found one that met all of my requirements and bought it below VRef. And I am still happy!

[Hank]

You, sir, sound too organized!

i was finishing up my PPL training, flipping through magazines at the FBO and trying to find what I could afford to operate after purchasing. The fuel burn on a 182 scared me. I asked people about planes that I saw (this will carry anything the doors will close on, that one glides like a sewer lid when you pull the throttle, those parts are super high, that plane has been sitting for years, it's junk, etc.).

The FBO owner had stumbled into a killer deal on an A36, and the Mooney he had been fixing up for himself as a retirement plane was available. We went to ride, he gave me some MAPA logs to look through . . . It was very distracting with my checkride coming up, and I managed to get through that. He agreed to sell it a half at a time. I figured he had more on the line than I did, selling to a freshly-licensed former student of his FBO.

Boy, that was the best decision I ever made! Changed my life for the better in many ways. Spent almost every lunch break researching Mooney flying, information, tidbits. Got severe eyes train reading Richard Zephro's site (Mooneyland? Who can forget electric yellow writing on black for one page, the next one is red writing on a green screen, blue writing on a yellow screen and other inappropriate choices). Then I stumbled onto early Mooneyspace.

Find a plane. See if you think it's good. Negotiate a price you're happy with. Then arrange an inspection by your mechanic, or at least not thenseller's, who knows about Mooneys. If it's good, pay the man so that your fun can start. There are some good looking ones for sale here . . .

[aviatoreb]

18 hours ago, Hank said:

Erik--why would you want to allow for both/either the value of the complete aircraft (a) or the installed avionics (b) to be less than zero? I've never seen something that I could be paid to take away, with the exception of other people's garbage. We are discussing airplanes here, not the contents of someone's trash can, although I admit the value can be much lower than the seller anticipates--that's why there are terms for Asking Price (x) and Valuation (a).

As for your concerns about recent repaint and undefined terms, I always thought X^0 = 1, and 0^X = 0. I also thought the equation should have been handwritten as N divided by everything else (silly ithingy doesn't have "divided by" symbol!), or written on a single line with parentheses as 

           Suitability = N/[(x+y+z+t)a^b+(z*r)b^a]

Similarly, I see no reason for your proposed "x+y+z+t>0" constraint, but I would support that x, y & r must each be > 0. It looks like t is binary, either t=0 for my wet wings or t=1 for someone else's bladders. Z could be anything, but it is difficult to pinpoint as some people are forced to overhaul well before TBO while others fly 20-30% or more beyond it with no condition issues. Maybe z should be redefined as "z = hours remaining to TBO" to allow for the real variation seen in overhaul times?

The difficult part then becomes assigning a value to N . . . . .

Just being thorough Hank.

Yes - so you see my point - theoretically an item can become so low in value that you need to pay to dispose of it.

I had an Apple II (no plus) I brought to college and I used it for a lot of college which I got in high school mowing lawns.  I was really proud of it.  When I graduated I went to a local computer store in Berkeley and tried to sell it used since they bought used machines.  They didn't want it.  I didn't want it anymore either since I had a small car and I needed to drive across the country to grad school.  So I offered to give it to them for free.  Finally I remember I had to pay them a few dollars to take it.

Ironically, now I understand a working Apple II has some retro-collector value on ebay.

Anybody want to buy a vintage soon to be collectable Loran?  

 

(x+y+z+t>0 was so you don't divide by zero.  x^0 is fine but x^1/2 is no good if x<0 unless you like complex dollars.  0^x is fine as long as x>0.  Mostly you know I am just being silly).

Edited March 18, 2016 by aviatoreb

[N33GG]

Aviatoreb, I was waiting for you to weigh in on this one.  I think the equation is painfully simple and not realistic.  There should be some differential relationships, as well as random functions to inject the unknown that will certainly arise somewhere.

And thank goodness we have imaginary numbers like i and j, or Electrical Engineers would be severely limited.

[aviatoreb]

34 minutes ago, N33GG said:

Aviatoreb, I was waiting for you to weigh in on this one.  I think the equation is painfully simple and not realistic.  There should be some differential relationships, as well as random functions to inject the unknown that will certainly arise somewhere.

And thank goodness we have imaginary numbers like i and j, or Electrical Engineers would be severely limited.

Hi George,

Well - the lack of a differential statement alone is not unreasonable because perhaps this is the solution of some differential equation?

Yeah - I too would more so expect a stochastic differential equation where the random forcing terms would describe the economy, your changing family and job situations, and somehow I am disappointed that the phase of the Moon was not included.

I always had a problem with electrical engineers because everyone else things i=sqrt(-1).  But electrical engineers think j=sqrt(-1) because they say i is already being used for something they think is even more important - go figure - electrical engineers think current is important.

i (i'll call sqrt(-1) i since I am not an electrical engineer), could be called just a convenience as used for a lot of uses in signals because you can just skip the e^i n theta stuff and write sins and cosines.  But then you really do need the complex analysis stuff for all the contour integration would get just too inconvenient without - and how else would you get the bromwich integral?!

As for me - when I bought a mooney - I used the old fashioned eeny-meeny-miny-moe method, which never fails me when the math gets too hard for me to actually do it and a bad model would be as good as guessing.  SO I skip the model and go straight to guessing!  Moe said buy a mooney.  Eeny said buy a Bonanza and meeny wanted me to buy a Cirrus.  Guess who won?  (Bonus question - what did miny want me to buy?)

[Deb]

Just now, aviatoreb said:

(Bonus question - what did miny want me to buy?)

A Mooney Mite?

[dlthig]

Yea, well, well... My degree is in History. I think that this means airplanes are expensive. 

[N33GG]

I'm pretty comfortable with both the i and j equations, and can actually flip flop between both letters.  When I started ee classes and learned i was NOT the square root of -1, I had to chuckle.  I probably lean more toward being a mathematician than an electrical engineer.  Having a good grasp of math and abstract concepts made my ee classes a lot easier, while others sometimes struggled due to lack of math.

But I must confess, although I consider myself above average in math, I still struggle with, and have never really mastered the eeny meeny miny moe technique.  Boy, and I thought convolving integrals was hard!

When it comes to aircraft, and a lot of other things in my life for that matter, I have completely abandoned rationale and logic.  I go with gut instinct.  If I had done everything opposite than what "experts" advised when my gut instinct was screaming another answer, I would be so far ahead.

Call me crazy, but gut instinct is your brain trying to get you to pay attention to something you haven't yet quite figured out yet, for whatever reason.  At recent FIRCs, they have shown us that studies of recent accidents reveal the crew was often talking about the accident before it happened.  Eg "hope we are not on the wrong course, there are mountains in this area" etc.

They advise if while you are flying, you get the feeling something is wrong, you should act on it immediately without delay.  Or, you could work on an equation to evaluate the probability of a real problem.  Or, you could go with the eeny meeny miny moe technique.  Unlike many in the FIRC, I am good to go with gut when the need arises.

But how I wish I could master that darned eeny meeny miny moe system!

[Hank]

My biggest concern with eeny meeny miny moe comes at the end:  should it be "you are it" as the final answer, or "you are not it" for additional rounds? Stinking ithingy just introduced another problem it changed the spelling of three of the four words!

[glafaille]

Wow!

Go away for a couple of days and my "Silly/Frustration" post takes off.  You guys are certainly an attentive, helpful and entertaining lot.

Thanks to each of you for the advice, encouragement and Algebra tutoring.  Algebra was one of my "barely  made it through" classes in high school.  Then I discovered computers and realized there really is a use for that stuff!

I went for a ride with a fellow Mooneyspace member the other day in his REALLY NICE B model.  Just a quick ride around the local area then lunch in town.  This gent had been looking for a Mooney for 8 months before he came across his current ride and has owned it for many years.

Looks to me like most folks either spend many months looking for the right plane or just luck into a deal at the local airport at a time when they were not even looking for a plane.  Looks like I am in the first group.

 

[1964-M20E]

15 hours ago, aviatoreb said:

....

i (i'll call sqrt(-1) i since I am not an electrical engineer), could be called just a convenience as used for a lot of uses in signals because you can just skip the e^i n theta stuff and write sins and cosines.  But then you really do need the complex analysis stuff for all the contour integration would get just too inconvenient without - and how else would you get the bromwich integral?!

...

I resemble that EE remark and current is really important just like airspeed, ground speed, head wind and tail wind. 

 

 

Edited March 19, 2016 by 1964-M20E

[Wakeup]

Relationships are a lot like Algebra.  Have you ever looked at your X and wondered Y?

[Danb]

On March 17, 2016 at 0:00 AM, glafaille said:

 

Suitability of aircraft for my mission at my price = N/(x+y+z+t)a^b+(z*r)b^a

As the equation approaches 1, the probability aircraft will meet my needs is 0.

 

I'm quite sure Anthony has this equation.

ERIK,. HANK.  What!