jordan ross

Davis Monthan Boneyard Tour  

By Jordan Ross 

 

As of 5-1-17 significant changes in procedure for taking the "boneyard" tour at Davis Monthan AFB in Tucson, Arizona, have been implemented.  The tours are run by the Pima Air and Space Museum (PASM) which is located next to Davis Monthan AFB.  In the past you could simply buy a ticket for the tour at the admissions desk, get on the bus, and be taken around the acres and acres of stored aircraft.  You could not get off the bus, but it was and is a most interesting tour.  

Anyone contemplating taking the tour needs to first read the information on the PASM website.

Now, when you go buy your tour ticket, the clerk will ask you to read a printout they have of the information which is on the website.  It contains information about what you need to do in order to be allowed to take the tour.  You must acknowledge you have read it and understand what it says.  

Note that tickets for the tour are sold on a first come, first served basis.  They do not sell them in advance or take reservations so the earlier you get there, the better the chances tickets will be available.  The museum opens at 9:00AM.  Check ahead to make sure they are open on the day you plan to go.  Tours are not conducted on Saturday or Sunday.

Once you have paid for your ticket, you go to another counter where a clerk will ask you for identification and your Social Security number which is recorded on a form you have to sign which includes a liability waiver.  You are then issued a boarding pass for the tour bus and assigned a number.

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You then go outside to the area where the line forms to get on the bus.  Boarding begins after the clerk who took your ID and SS number brings the driver and docent what they call "the paperwork" which they have to show to the USAF military police once you get to the base.  Side note: it would be wise to use the restroom before getting on the bus.

To get on the bus you need to again show your ID (drivers license in my case) and give the docent the boarding pass you were issued.  The bus is a very nice one.  Big, air conditioned, comfortable seats, and with huge windows making viewing and photography easy.  The docents who narrate the tour are knowledgeable and friendly and most willing to answer questions from the guests, and so was the bus driver.

The bus takes the group to the main base entrance, about a 10 minute drive from the museum.  Upon arrival the bus goes to what is called the "holding area" manned by armed military police.  Everyone has to get off the bus and take their possessions with them.  Passengers are directed into a building used to inspect vehicles.  Once everyone is in the building the doors are closed until the military police have concluded whatever passenger checking and bus inspecting they need to do.  Assuming no problems, in about 15 minutes everyone is allowed to re-board the bus and the tour begins.

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The main gate is on the far side of the base from the boneyard which requires the bus drive through the main part of the base to get to it.  No photography is allowed until the bus arrives at the start of the boneyard tour.

The tour itself is very well conducted.  The bus slowly creeps along the roads between rows and rows of stored aircraft and the docent explains what kind of aircraft they are, what role they served, and a little history about the more interesting ones.  It takes around an hour and a half to complete the tour circuit.

 

Assuming you have no problem with the security driven requirements to take the tour, I highly recommend it.   Just be prepared.  Whether you take the tour or not, a visit to this great museum is always a wonderful experience.

 

 

 

Now that you have reached your cruise altitude, you can switch off the fasten seatbelt sign and take a moment to relax. If you are in a technologically advanced airplane, or carrying a tablet, you are probably looking at multi-colored LCDs throwing all sorts of information at you. My Electronic Flight Information System has readouts of fuel flow, range, miles-per-gallon and indicated/true/ground speeds. Is there a way to minimize fuel flow, maximize MPG, and maximize airspeed all at once? Probably not, but we will explore the factors effecting each and some other performance metrics that we may not normally think about.

 

Maximum Time Aloft

The airplane's time aloft or endurance is its fuel on board (gal) divided by fuel flow (gph). To maximize time aloft, one must maximize fuel capacity and minimize fuel flow. Fuel flow is minimized by using the least amount of power to sustain flight. This is the bottom of the power required for level flight curve. On an endurance flight, as fuel is consumed and the airplane weight decreases the minimum power required will decrease and the throttle can be reduced. To fly for maximum endurance, you will be flying really slow, at or near your Vx speed, so this is rarely done in general aviation. An example of when this would be useful is on an observation mission where the airplane needs to remain on station for the longest possible time.

 

Best Miles per Gallon, Best Range Speed

This probably gets your attention because now we are talking about saving money. The best miles per gallon will result in the maximum range of the airplane. Another way to express it is that this cruise speed will use the least amount of fuel for a given trip distance. The fuel used on a trip depends on fuel flow and the time it takes to make the trip. So now we need to minimize fuel flow (keep power low) but make the trip fast enough to use as little fuel as possible (keep power high!). The middle ground is found at the bottom of the L/D curve of the airplane and is close to, if not the same as, the Vy speed. In the interest of saving fuel, we get to fly a little faster but still at a relatively slow airspeed.

 

Best Speed per Gallon

Optimum cruise speed was derived by B.H. Carson of the U.S. Naval Academy in 1980. For those of you that can remember back that far, this was after the oil embargo. Suddenly the country was focused on the fuel efficiency of cars and airplanes. Carson addressed the question of using miles-per-gallon as the optimizing metric for airplanes. He noted that for airplanes the speed for optimum fuel efficiency was quite slow and utilized only a small percentage of the airplane's available horse power. Instead he derived a new metric, the optimum cruise speed which maximizes the speed of the airplane relative to fuel flow. It is the best speed per gallon-per-hour ratio that can be achieved. The optimum cruise speed that he derived is 1.32 times the best miles-per gallon speed. It is a bit more practical than flying at best range speed.

 

Here are the V speeds discussed in this article derived from the performance charts I measured during the flight test period of my RV-10. The blue line is the thrust required for level flight and is read from the axis on the left in pounds. The red line is the power required for level flight and is read from the vertical axis on the right in horsepower. The maximum endurance speed is a very slow 70 KIAS and only requires 57 horsepower from the 260 horsepower engine. The maximum range speed is 90 KIAS and requires about 100 horsepower. The optimum cruise speed is 120 KIAS, still somewhat slow, but better, and requires around 120 horse power - still only 46% power.

 

Next month we will discuss how to determine these performance curves for an airplane through flight testing.

 

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