This is where I see the general problem with interest rates in AS:
In AS, interest has to be paid on a weekly basis, calculated on the loan remainder. We've 260 interest periods for aircraft bound loans and 50 periods for unbound loans.
This vast number of periods is what makes loans so expensive in AS.
Just for comparison:
A real loan often has a duration of 12 years, with monthly installments but interest paid annually. That makes 144 installments and 12 interest periods as opposed to 50 or even 260.
Now let's do a quick calculation (please report possible errors as I'm writing this down quickly):
Say we buy an aircraft on loan for 100m$, interest is 1.5%, 260 periods:
The total interest is (100m/2)*0.015*(260+1) = 196m$ - that's twice as much interest as the aircraft itself would cost us if paid "cash".
Initial weekly charge: 100m$/260+100m$*0.015 = 1,884,615$, average weekly charge: 1,135,573$
A 100m$ airframe on lease would cost you 500,000$/week - the extra 635k$ can hardly be considered self-supporting.
Now let me try a different approach with the following suggestion:
Let's adapt the real business model of 144 installments and 12 interest periods => 144 weeks with interest only maturing every 12 weeks.
Again 100m$, interest 1.5%, 144 installments, 12 periods:
Total interest: 9,75m$
Initital weekly charge: 100m$/144+100m$*0.015/12 = 819,444$, average weekly charge: 761,686$
We're fairly close to the leasing costs here and rising or decreasing interest rates have a much lesser effect.
Bear in mind that all this has to be considered with reagards to a balanced gameplay, neither favouring lease nor loans! But the above example looks fairly close to this approach IMO.
Martin, sk? ;)