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The future light twin for General Aviation – it is this type of thinking that we need more of!

Aviation Thoughts 2 Comments

I recently was reading in Aviation International News (http://www.ainonline.com/), about a concept business airplane that would be part hovercraft, part corporate King Air with ducted fan technology. The airplane concept is seeking funding, and if you would have an interest in being a part of the development, just visit here – http://www.xtiaircraft.com/trifan-600/ The problem is, the reality just isn’t here in my opinion, as VTOL aircraft have been in the dreams of many, only to find that you just can’t make a practical VTOL airplane to work.  The required thrust is such that even a very efficient turbine engine isn’t going to give you the capability to make it work.  But…there are some ideas out there that SHOULD be sought after, that have real possibilities and can be put into production.  Lets take a look at this!

If you note, this subject and post is in my “aviation thoughts” category.  I am always for advancement of general aviation, I am just at the point of frustration with aviation designs that have a very poor chance of making it in the marketplace.  When it comes to the Terrafugia flying car, I like the novelty, but know it won’t make it in the marketplace mainly due to performance compromises, which will show with a lack of demand at the end of the day. If this doesn’t make sense to you, please post your comment and I will explain it – although it is relatively elementary.  The Icon-5 is another airplane design…that is cool in it’s concept, intent, and flare for automotive thought processes, but the marketplace isn’t going to support this airplane.  Why?  It is in a very narrow point of demand, just not enough people with $250,000 that want to go out and enjoy recreational aviation – the airplane just doesn’t have the performance in cruise, climb, and in practicality to make it go.

The TriFan 600 is in the same category, it offers too many compromises at a price that won’t make it in the marketplace.  I know where they are going with this, the fly-by-wire technology enables control of an airplane in the transition to and from a hover, but the necessity of fuel efficient operation isn’t part of the reality. It takes so much power to lift a heavy airplane like this will be, it will require two engines in this case, burning a lot of fuel.  There will be some who would buy it for the convenience, the imagination that goes into how an airplane with this capability is very appealing, it just has too many compromises to make it a viable airplane.  Sure, the flying model may demonstrate the technology, but when you put it to full scale – OH, OH!  I could be all wet on this, but I would hedge my bets that I am right.

Which brings me to the concept airplane that was brought to my attention recently.  It is from a designer who for all I know, doesn’t work in the aviation industry. Dragan Ristic <dragannristic@gmail.com>, the designer of an airplane two years ago, thought about a high performance twin engine “piston” powered airplane.  Thinking about it, I am sure he looked at a clean design, something that would be fast, convenient, and have a lot of utility value.  Pressurized for speed in the flight levels, easy to convert to a freighter, and economical to own and to operate. To me, these are top priorities for an airplane design.  The second priority – can it all come together to work?  Is this a practical reality, because if it is a theory, then chances are you are missing some type of physics vs. reality that one needs experience in airplane design to make it happen.

View of the Dragon twin engine concept with gear retracted at cruise altitude.

View of the Dragan twin engine concept with gear retracted at cruise altitude.

In my mind, Dragan is on to the right market, the light twin market is almost completely abandoned, but has that niche where an airplane will sell in the marketplace. A turbine offers performance, but cost a lot more to operate, especially on short hauls.  The other side of the market, is the single engine piston market, which doesn’t offer the capabilities of a pressurized twin engine airplane can, ever fly over the mountains at night?  Give me two engines please! But if you could lower the cost per mile by half over a turbine airplane, and be just as fast, why wouldn’t the airplane sell to small business owners, charter operators, and freight haulers?

The alternatives in the marketplace, and I am comparing brand new airplanes, since the design is essentially going to be brand new, we can find the price point and performance come together very nicely.  Go turbine and you are going to spend $2.3 million for a Piper Meridian, and approximately $3.5 million for an entry level jet.  You can buy a new King Air C90GTx for a nice price of $3.8 million, which if I were in the market for an all around good corporate airplane, this would be my choice…the King Air is just tough to beat for all around balance performance, safety, and most of all – room! IF you could buy a light twin that was economical to operate, and priced in that $1.5 million dollar range, the airplane would sell a profitable number of units.

So we have this void between a piston single, to the turbine powered airplane, with not many options in between.  This is why I would consider Dragan’s idea and concept, a very good market placed airplane, and if he can deliver somewhat close to the performance estimates, the airplane will do well in the market.  Although the engines appear to be a turbine, the designer is looking into the rotary engine development from Mistral Engines SA http://www.mistral-engines.com/  Check this engine out, it has potential, it obviously needs some serious capital to be continued in development, and could be the answer to the next generation of economical powerplants for aviation.

Dragan Ristic concept of light twin while on the ground.

Dragan Ristic concept of light twin while on the ground.

The airplane looks similar to a Citation Mustang with the engines replaced by these rotary powerplants, but I like the configuration because proportionally it looks right.  The rotary engines from Mistral is my concern, but THIS is where I believe more development needs to take place in general aviation!  IF you could get the engines in production like the company wants to, you have a powerplant that can run on regular pump-gas + ethanol if that is what you have at your BP or Sunoco gas station. It is a FADEC engine, with a TBO goal of 3,000 hours along with minimal maintenance, this is something I have been saying all along that is needed.

Dragan estimates performance in the area of a 300 + knot cruise at FL 250, which considering area rule for this airplane, I am not so sure is attainable.  However, if you could achieve 250-260 knots on a fuel burn of 35 to 40 gallons of regular fuel, you have something.  Anytime you are pushing the 300 miles per hour cruise speed, you can put the airplane coast to coast in a single day, and if you could do this with the economy of a “piston” powered airplane, you have something that will be very appealing to many people. Obviously the airplane would need a lot of development, the airframe is one thing, the engines would be an entirely new issue that would have to be dealt with.  Looking at the photos of the airplane, the simplicity of the renderings is one thing, tackling the cooling and the complexity of an exhaust system for the engines, you will need some serious talent to find the answers.

So what makes this airplane unique in the marketplace?  First, it is a good looking airplane, something modern that will appeal to buyers in the marketplace.  Second, the performance and efficiency will improve, based on aerodynamics and with a liquid cooled engine, you should be able to reduce cooling drag, which is critical as drag increases with the square of velocity. Included with the modern airframe, is the unique bonus of single engine safety and low VMC from the almost centerline mounted engines, which should show good behavior and performance on one engine. If the price per mile were significantly lower than the closest twin engine turbine, you probably couldn’t build the airplane fast enough to meet demand.

And this is where I am going with this, general aviation needs more investment in airplane types that would find a marketplace willing to fork over the capital to purchase the airplane.  By having an increase in performance, low operating cost, and new technology are all a combination that has proved successful time after time.  In addition, having a common fuel to the automotive world is the answer I am looking for, because the refining of fuels, and the distribution of specialized fuels, is what costs money that can’t compete with the market price of oil.

I could write for weeks about the pros and cons of a rotary engine, but believe it is a good adaptation to the replacement of the current air cooled airplane engines currently being utilized.  A rotary engine is very smooth – almost turbine like, and as Mazda has proved, they are very reliable and very low maintenance.  They can run on almost any type of fuel, which eliminates expense and the availability of 100LL in many parts of the world.  To build airplanes, you need all the combinations of price, value, safety, performance, and good looking never hurt!  If I were to invest in an aviation technology, the light twin concept that has useful load, economy of operation, and has potential, THIS would be it!

2 Responses to “The future light twin for General Aviation – it is this type of thinking that we need more of!”

  1. Ben Says:

    Totally agree. I like the Beechcraft Baron and Diamond twinstar. If economic fuel burn and affordable price point could be found it would a great plane.

  2. admin Says:

    I have always been a Beechcraft A-36 guy in the piston engine singles, and the Beechcraft P-58 in the piston twins. The Cessan 340/414A/421C are nice airplanes, I probably have about a 2,000 hours in them +, but for a personal airplane, I like the Beechcrafts. I did fly a Diamond DA-40 and liked it, visibility was outstanding, but the A36 just gets up and goes and I like the club seating.

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