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Why Are We Still Not Yet Privately Flying at Mach 3?

by Jeremy Cox 1. July 2006 00:00
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In my estimation, Friday the 24th of October, 2003 was indeed a very sad day for the entire world. This is the day that the 27 year long Concorde Program at Air France and British Airways came to an end. Even though we had crossed into a new Millennium, we took a major technological step backwards. From that day on, military personnel became the only people that are able to fly anything above Mach 1. As the Sunday Times columnist, Jeremy Clarkson put it as he was contemplating his seat on the very last scheduled flight of Concorde from John F. Kennedy, New York to Heathrow Airport, London, on that fateful October's day: "As I step off, the temptation will be strong to say ‘That was one small step for man. But one giant leap backwards for mankind.'"

Yes, Lockheed, Boeing, General Electric, Pratt & Whitney and the FAA had all worked on the development of an American, Mach 3, Super Sonic Transport (SST), starting in the mid 1950's, unfortunately however, this entire scheme was scrapped in 1965 because of the fear of the costs that would have been involved. Meanwhile across the ‘pond' in 1962, the British and French governments decided to commission the Mach 2.4, Concorde project. Additionally the Russians also built their Tupolov 144 which actually did work, but which ultimately failed due to its feeble 1,500 mile range. Also its crash at its debut at the Paris airshow didn't help either. Scheduled services for the Anglo/French Concorde began on Wednesday the 21st of January 1976. Amazingly, as Jeremy Clarkson points out: ‘For the first time, paying passengers could fly so fast they could watch the sun rise in the West (sic) and arrive in America before they left home.' For the next 27 years, the Concorde flew three-quarters full and made close to $40,000,000 a year for British Airways. With the demise of the Concorde, the Cessna Citation 750 became the world's fastest general aviation aircraft, ringing in at Mach 0.92, closely followed by the new, yet to deliver, Dassault Falcon 7X at Mach 0.90.
With the one and only SST type being grounded almost three years ago, why are there no other SST aircraft currently operating? Well before I attempt to answer this question, I will first try and provide a brief overview of the dynamics of Supersonic flight.

What is considered to be ‘Supersonic speed?'

Aircraft speeds have been defined as follows:
Subsonic Mach numbers < 0.75
Transonic Mach numbers > 0.75 to <1.20
Supersonic Mach numbers > 1.20 to <5.00
Hypersonic Mach numbers > 5.00

What is a Mach number?
Mach is the ratio of true airspeed to the speed of sound, i.e. V÷M= a

M = Mach Number
V = True Airspeed in Knots
a = Speed of Sound in Knots.

The Speed of Sound in air depends only on the Static Temperature of the air, decreasing with lower temperatures and increasing with higher temperatures. The speed of sound is 762 MPH (663 Knots) @ ISA (59°F/29.92" Hg) @ SL; 660 MPH (574 Knots) approx @ -50°F approx @ 100,000 Feet.

To actually break through the Sound Barrier and cruise at Supersonic speeds, an aircraft must have immensely powerful engines. This is why the four Rolls Royce Olympus engines on the Concorde had a system of jet exhaust nozzle ‘re-heat'; some people call them ‘after-burners.' Immense Power is needed to overcome the increase in Drag. The Drag rises with the Square of the Velocity, while the Power, which is Drag times Velocity, with the Cube of Velocity, i.e:

D = V² & P = D*(V³)
D is Drag V is Velocity
P is Power

Intense Heat is another by-product of Supersonic flight. It is actually Compression and Skin Friction which causes an extreme Temperature Rise of the Air surrounding the Aircraft. This can be illustrated by the following table:

Speed Temperature Rise
Mach 1 230°F
Mach 2 610°F
Mach 3 1,200°F

Concorde used to fly between Mach 2.2 to Mach 2.4 only, by design. This was to avoid the deleterious molecular altering effects of aerodynamic heating. This is because the temperature range at which aluminium alloys lose their strength is >250°F. This design specification thereby allowed the Angle French program to avoid the need to employ the use of expensive hybrid materials like titanium, nickel alloys, ceramics and ablative coatings, thus keeping the production costs much lower than they could have been if they had, like the Americans, attempted to operate at Mach 3.

The best known, and probably the most politically incorrect, negative side-effect of Supersonic flight are the Sonic Booms that are a result of the production of Shock Waves. Shock-Waves are technically a result of Compressibility Drag. To reduce this phenomena, the Wings generally have to have a thinner cross section, and also have a pronounced span-wise aft wing-sweep, with wing fences to delay and change the formation of Shock-Waves. Unfortunately wing sweep can accentuate tip-twist, wing tip stall and ‘Dutch Roll.' However with current aerodynamic design, now most supersonic aircraft (military) tend to generate two main shock-waves: One at the Nose (bow wave shock) and one at the Tail (tail shock.) Sonic Booms are basically caused by the folding, unfolding, refolding, and final unfolding of the air as a supersonic aircraft passes through it. The two shock-waves formed by a supersonic aircraft create this transitional folding effect, i.e. ‘compression' * ‘decompression' * ‘compression' and a final ‘decompression' resulting in two sonic booms that may be heard at ground level.

The negative effects of Shock waves also extend to the possible creation of Wing and Compressor Stall. What I mean by this is that the formation of shock-waves change the relative airflow around the aerofoil's of the wings/tail, etc. and unfortunately also the Compressor Blades in the inlet of an axial flow, jet-turbine engine. Shock-wave penetration or modification devices must be employed to change the airflow effect of a shock-wave. If you have ever looked at the complexity of the series of vanes and blocker doors that were designed into the air inlets on the Concorde, you will better understand the vital need to modify the pattern and flow of the sonic air before it enters the engine compressor. Additionally the amount of engine power output is also governed, to a certain extent, by the inlet temperature of the air entering the compressor, i.e. the colder the air is, the better the power output is. Frictional heating will have a drastic effect upon the total power output of the engine, if it is not controlled.

Finally another factor that must be considered in Supersonic operations is the quality and properties of the Jet Fuel used. Due to the extreme ambient conditions that a supersonic aircraft must operate within, the fuel must be refined and blended to an optimized performance level that provides a high BTU, a low volatility, a high flash point and a low freezing point.

So as you can see, Supersonic flight has a lot of technical obstacles that must be overcome to achieve success. However, all of these obstacles have been conquered in various ways by many multi-national aircraft manufacturers and therefore I believe that it is a valid question, when we ask again: ‘Why are we still not yet privately flying at Mach 3?'

Well hopefully we may be able to do so shortly after the end of this decade. This is because research and development in this area has not ceased. Although several companies have tried to develop their own Supersonic Business Jet designs, but have so far failed to bring an aircraft off the drawing board into the marketplace. Most notably these failures include a joint project between Sukhoi and Gulfstream with their S-21 and Dassault Aviation and Boeing separately in the early 1990's. Currently there are three companies that report that they are developing their own Supersonic Business Jet Aircraft. These companies are: Aerion Corporation; Tupolev and SAI.

Aerion Corporation is working on an F104 Starfighter inspired business jet that will carry eight to twelve passengers at 51,000 feet, just slightly below Mach 2.0. It is scheduled to deliver in 2011 and is targeted to cost $80,000,000.00 USD per copy.

Tupolev is reporting that they have developed a hybrid of the TU144, which is called the TU444 Charger. This aircraft is designed to carry six to ten passengers over 4,000 nautical miles at Mach 2.0. There is no reported delivery date or cost.

SAI (Supersonic Aerospace International, LLC) have employed the services of the Lockheed Martin ‘Skunk-works' design team that originally designed the SR-71. This group are spearheading the Quiet Supersonic Transport (QSST.) This aircraft is designed to carry 12 passengers over 4,000 nautical miles at speeds between Mach 1.6 to Mach 1.8. The surprising aspect of this design is the aerodynamically shaped sonic boom signature that is 1/100th of the booms generated by Concorde. This sonic boom suppression technology should, according to SAI, allow their aircraft to fly at Supersonic speeds over populated land areas, instead of being restricted to Supersonic flight only over the sea.

It is sad that it appears that no-one is shooting for the kind of speeds that the great Concorde used to achieve on a daily basis, but it is terrific to see that ability to privately fly above Mach 1.0 is still under development by several stalwart companies. I wonder though, if we will ultimately be prevented from achieving Supersonic speeds even if any of the aforementioned aircraft do actually make it to the prototype stage, because the draconian security people like the TSA, who appear to be imposing unreasonable and ungrounded legislation specifically against aviation, may decide ‘No' civilian Supersonic travel is too much of a security risk!?! I certainly hope not. Interestingly enough, the North American-Rockwell Space Shuttle actually re-enters the earth's atmosphere at an incomprehensible speed of Mach 25.0, so maybe we should be working on Shuttle type transports in place of the current designs in-play?

So, have you heard of any other civilian Supersonic aircraft designs that are currently in-work? Maybe you were fortunate enough to have flown on Concorde, and you have some reflections of this experience to impart to us here. Any input that you care to make will be of great interest to all of the readers here at Globalair.com. So please don't be bashful and go ahead and write your comments and suggestions here. Please don't forget that whatever you write here, can be seen publicly by everyone that visits this page, so please be funny, be inspired, but most importantly of all, please be nice. See you next month.



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Jeremy Cox

Obtaining an Exemption From a Federal Aviation Regulation

by Greg Reigel 1. July 2006 00:00
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The rules exist for a reason. So we are told. But must we always follow the rules? Not necessarily. Sometimes it is possible to receive an exemption or excuse from compliance with certain rules. In the aviation world, it is possible to obtain an exemption from certain Federal Aviation Regulations ("FAR's"). As matter of fact, exemptions are frequently requested. However, they aren't necessarily granted. This article will discuss the process for petitioning the FAA for an exemption, some of the exemptions that the FAA has granted and some of the exemption requests that the FAA has denied.

Petitioning For An Exemption

A petition for exemption is a request to the FAA by an individual or entity asking for relief from the requirements of a current regulation. Petitioners typically seek exemptions from FAR's that they feel treat them unfairly or which may be overly burdensome on their intended operations. Petitioners can be individuals (e.g. pilots, mechanics, etc.), businesses (e.g. manufacturers, commercial operators, etc.) or organizations representing individuals or businesses (e.g. NBAA, AOPA, EAA, etc.). The process for obtaining an exemption is governed by FAR Part 11. Part 11 describes the procedures a petitioner must follow to petition for an exemption and the manner in which the FAA will handle a petition for exemption.

A petition for exemption must be filed with the FAA and may be sent via U.S. Mail or filed online. In addition to the petitioner's contact information, the petition should include (1) the specific FAR(s) from which an exemption is sought; (2) the extent of relief the petitioner is seeking and the reason the petitioner is seeking the relief; (3) how the request will benefit the public as a whole; (4) reasons why the exemption would not adversely affect safety, or how the exemption would provide a level of safety at least equal to the existing rule; (5) a summary the FAA can publish in the Federal Register stating: the rule from which the petitioner is seeking the exemption and a brief description of the exemption the petitioner is seeking; (6) Any additional information, views, or arguments available to support the request. Additionally, if the petitioner would like to exercise the privileges of the exemption outside the United States, the petition should provide supporting reasons.

Within 45 days of receiving a petition for exemption, the FAA will often, although not always, publish a summary of the petition in the Federal Register seeking comment to the petition. The public typically has 20 days within which to provide the FAA with comments to the petition. Once any comments are received, the FAA will then issue a written decision granting or denying the petition, usually within 120 days. It will often then publish its disposition of petitions for exemption in the Federal Register.

The FAA has discretion as to whether it will grant or deny a petition. In each instance, the FAA will provide an explanation of its decision and its impact on the petition. It may grant the petition as filed or it may grant the petition with conditions or limitations. If it is granted, the petition is only granted for a limited time and will expire unless it is renewed by the petitioner.

The FAA may also deny the petition. If the petition is denied, the petitioner can ask the FAA to reconsider the petition denial. The FAA must receive the request for reconsideration within 60 days after it issued the denial. In order for the FAA to accept the request, the petitioner must show the following: (1) that the petitioner has a significant additional fact and an explanation of why that fact was not included in the original petition; (2) that the FAA made an important factual error in its denial of the original petition; or (3) that the FAA did not correctly interpret a law, regulation, or precedent.

Exemptions The FAA Has Granted

The FAA has granted and continues to grant exemptions from certain FAR's. As an example, over the years the EAA has requested, and been granted, several exemptions from specific FAR's including the Small N Number Exemption (exemption from FAR's 45.25 and 45.29 to allow its members to operate their historic military aircraft with 2-inch high nationality and registration marks) and the Experimental Aircraft Training Rental Exemption (exemption from FAR 91.319(a)(1) and (2) to allow members who own certain amateur, kit-built and exhibition aircraft to receive compensation for the use of their aircraft for the purpose of conducting aircraft-specific flight training and flight reviews under FAR 61.56).

And just today, the FAA published Notice of a petition for exemption filed by the EAA requesting an exemption to permit sport pilots' who have not received the required ground and flight training, and endorsements to operate within the Wittman Regional Airport (Oshkosh, Wisconsin) Class D airspace during the period July 22, 2006, through July 31, 2006, for the purpose of attending AirVenture 2006.

Individuals and other aviation organizations have also applied for, and been granted, a variety of other exemptions such as the exemption from drug testing for charitable sightseeing events and the exemption allowing a flight instructor to provide dual instruction in a Beechcraft Bonanza with a single throw-over yoke, to name a few.

Exemptions The FAA Has Denied

Not all petitions for exemption are granted. Many are denied. For example, AOPA and many individuals have petitioned for exemptions from the Age 60 Rule (FAR 121.383(c)) for many years. Unfortunately, the FAA has denied all of these requests. Another example of a denied request is the Confederate Air Force's petition to exempt its operation of its Lockheed T-33 turbojet aircraft for compensation contrary to FAR 91.319(a). These are just two of the multitude of petitions the FAA has denied.


As you can see from these examples, it is possible to obtain exemptions from some of the FAR's. However, not all petitions for exemption will be granted. The FAA places a significant emphasis on both the public benefit and safety requirements. If you are requesting an exemption, you will need to persuade the FAA that the benefit of your intended operation is worth the anticipated non-compliance. You will also need to provide the FAA with the data necessary to convince it that the intended operation can be conducted safely despite the anticipated non-compliance. And keep in mind that the FAA has discretion as to whether a petition is granted or denied. However, if you give the FAA what it wants, you just may receive your exemption.

Give us some of your examples and experiences we would love to have your input on this!  Your input could possibly help a fellow aviator out!

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Greg Reigel

Is It a Good Time to Buy?

by David Wyndham 1. July 2006 00:00
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It is said that the optimist and the pessimist agree on only one thing, "This is as good as it can be." This applies to today's turbine aircraft market. The optimist is thrilled at the selling prices they can get for their client's used aircraft, and the pessimist is proven correct when they look at the selling prices they have to pay to get their client a good used aircraft!

New or used, the overall story is about the same. A friend selling new aircraft wanted to hire a new salesperson. They couldn't because the manufacturer is sold out well into 2007. With no new planes to sell and deliver this year, they won't hire someone to sell airplanes they can't get. Many of the new aircraft available, including the nascent Eclipse and Mustang, are sold out for several years (2009 said Cessna for the Mustang). Take a number, send us a check and we'll call you.

I took a look using the AMSTAT aircraft for sale database of turbine airplanes. As of this past week, 11% of the entire active turbine fixed wing was for sale. As a rule, this indicates an overall balanced market between buyers and sellers. However, the full story is hidden.

For current production models, only 3.2% of the active fleet is for sale. This indicates a very hot market for late model turbine airplanes. This also means that there is a weak market for older aircraft. As I see it, you actually have three markets ongoing right now:

New and nearly new turbine airplanes – about 10 years and newer are very hot. This is a seller's market. Folks who can't get into new equipment right away are looking here for aircraft. Prices remain strong and interest isn't likely to wane for some time.

"Middle-aged" turbine fixed wing – between 10 and up to a maximum of 20 years of age. This is a balanced market. There are so good deals and some not so good deals to be had. Aircraft with updated avionics, RVSM, current aging aircraft inspections, and Stage 3 noise compliance are doing OK with reasonable prices if you are patient. This is a balanced market.

Older aircraft – about 20 years and older and/or non-RVSM/Stage 2 noise. It isn't doing well, hasn't been doing well, and isn't likely to improve much. Sure, there are some decent aircraft in here, but buyer beware. There aren't many buyers looking at these so either you are a bargain hunter with hard of hearing neighbors at your airport, or can't afford anything newer! Seriously, residual values of this group aren't great. Many are approaching their "scrap value" where their values are highly dependent on engine status and any recent maintenance. If they are non-RVSM, they have been sitting for sale for a while – many well over one year.

As an example for each group, I'll use the Citation family. Not to pick on them, but there are many models to choose from and production goes back quite a number of years so there are some good examples. One of the newest, the Cj2, shows 15 aircraft for sale with an average days listed of only 88 days. Go to the Citation Ultra, 22 are for sale with an average listing of 181 days. The oldest model, the Citation 500, has 75 for sale with an average days listed for sale of 761! The older models are taking much longer to sell.

So, the pessimist is right and the optimist is right. It all depends on what you are selling or looking for. If you buy a newer model, expect to pay close to full retail, but you'll be able to sell it in a few years. Buy a much older model; you'll get a bargain but plan on keeping it until the wings fall off (figuratively).

Have you or your company recently completed an acquisition?  What are your feelings toward the market trend right now?  Did you find a market that was very tight (and drove prices up) but was an older aircraft?


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