Simple formula for estimating airplane ceilings

The aeronautical engineer often has occasion to estimate the absolute ceiling of an airplane for which a detailed performance calculation is out of the question. In such cases it is customary to use either empirical performance charts or formulae. The performance charts given in several of the recent works on aeronautics are satisfactory so long as the airplane under consideration does not depart too far from the average in its characteristics. The formulae, with one exception, are no better. Given here is that exception, with indications of which terms of the formula may be neglected without seriously affecting the results, thus simplifying the task.