• Frequently Asked Questions.
• Frequently Asked Questions. You're a small company, can we trust you?
How reliable are your aircraft data, and how do you get them?
What about the methodologies? Is Piano a 'black box'?
So if we get the code, does this mean we can add our own methods?
Will Piano handle supersonic aircraft?
Will Piano run on Windows PCs?
Could you tell us who are your competitors?
Is it possible to buy your data on just one aircraft?
I see Piano can handle environmental emissions. How about noise?
Is Piano easy to learn and use?
Is there anything you're not telling us about Piano?
What does "Lissys" stand for?
Lissys was originally short for Lisp Systems (Lisp being the software language). It's pronounced with a short 'i', like 'miss'. It also happens to be the Greek word for 'solution' (the spelling is of course different, but phonetically it's the same), which starts with the letter lambda, hence the logo.
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You're a small company, can we trust you?
Evidently, yes! Lissys has been going strong for 18 years plus, and the customer list speaks for itself. Small means dedicated (to the point of obsession) and gives a naturally integrated product that no corporate philosophy can match. In this particular game, size is almost inversely proportional to stability and quality. If you'd like to contact some users for their opinions, just ask.
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How reliable are your aircraft data, and how do you get them?
The data come from all sorts of sources, both private and public. As is always the case, experience and connections help. No information provided confidentially to Lissys is ever disclosed. The database is not endorsed by any manufacturer, and is clearly identified as being Lissys' best estimate, not a reflection of guaranteed specifications. But be sure that a lot of work goes into it. Summary notes are associated with each file, giving an indication of its calibration status. Lengthy notes imply very good fits.
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What about the methodologies? Is Piano a 'black box'?
Piano's underlying methods draw from many different industrial and academic sources. They are derived partly from first principles (e.g. performance calculations), and partly from the kind of classical, semi-empirical, semi-theoretical work familiar to any good old-fashioned aeronautical engineer. When possible, references are included in the interactive version of the guide built into Piano. Subject to a confidentiality agreement, the actual source codes are supplied to customers with the 'Industrial' option. They are directly accessible from inside the guide, searchable, and automatically cross-referenced. The implementation is fairly English-like, and can be sufficiently understood by a user willing to put in some effort. Nevertheless, there is no complete answer to your question. Piano is indeed a complex system covering a vast multidisciplinary subject. But its architecture is the total antithesis of a 'black box', and industrial customers with support contracts will find Lissys entirely open and helpful in all areas. Otherwise, Piano's gradual development would have been impossible.
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So if we get the code, does this mean we can add our own methods?
Tough question. In principle, yes (strictly for internal use). In practice, it's non-trivial: First, you'll need some knowledge of the underlying language. Secondly, you run the risk of conflicting with future Piano developments. Lissys may sometimes be able to add modifications for you. If your methods are strictly confidential that may not be acceptable, although one solution is to leave out some vital pieces of code (e.g. constants) that can then be 'patched in' by the customer in-house through a simple mechanism. This has been done before, for example with internal DOC methods. But no general answer is possible, it all depends on your specific needs.
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How accurate is Piano?
In terms of preliminary design, it's as accurate as the best tools available anywhere in the world. This doesn't mean that Piano claims the same depth of analysis as, for example, preliminary design procedures that Airbus or other major manufacturers might use internally. But such procedures require a far greater level of detailed input, and time, and often involve several departments. They are of course better matched to the techniques and specific market of the particular manufacturer, which also implies they may not perform as accurately when examining the products of others. For the typical number of inputs that Piano uses, it can model an enormous range of types (from a tiny Eclipse to an A380) better and faster than anything. Hard numbers depend on specifics (a 'percentage game' is all too easily played without clear reference baselines). Nonetheless, as an example, the best globally-applicable wing weight predictions tend to have mean errors of the order of 9% rms, which is as good as possible considering the wealth of design approaches used in wing construction. On the other hand, in terms of pure in-flight performance prediction Piano will do substantially better than 1%, say for a detailed range calculation. If everyone uses the same aerodynamics and engine, and the same flight rules, yet some other predictor differs from Piano noticeably more than that, then that predictor is wrong.
In terms of the database, each individual aircraft is typically adjusted to match some significant numbers quoted by the manufacturer (e.g. MTOW, OEW, design range) either precisely or nearly so. This is not difficult and can be done through many different parameters.
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Will Piano handle supersonic aircraft?
No.
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Will Piano run on Windows PCs?
Amazingly, yes. Piano has now been ported to Windows.
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Could you tell us who are your competitors?
Sure! Because, in all seriousness, there are no competitors to Piano. There are other well-known tools for aircraft preliminary design such as Darcorp's AAA and Dan Raymer's RDS. Both promote their claims to analyse a variety of configurations ranging from unmanned military drones, bombers and fighters, to general-aviation aircraft and multi-surface configurations. But it is precisely by focusing exclusively on conventional commercial subsonic aircraft that Piano is able to deliver an outstanding product instead of a jack-of-all-trades, as evidenced by its list of customers and its database of more than 400 calibrated aircraft models. If one is looking for a supersonic stealthy crop-duster, Piano is certainly not the answer.
At the opposite end, there's PACE from Berlin, which was originally limited to performance evaluation with no design capability. Assuming you possess all aerodynamic and engine data from the manufacturer, PACE is geared to batch-like airline route analysis. And although Piano is not tailored as an everyday route planning tool, it can address any flight performance issue that PACE can, and does so from one single menu and dialog (see manoeuvres and sequences). PACE (who advertised a design capability in a brochure showing a white airliner with vertical lift-fans at the wing roots) claim that they can 'process Piano data'. That's sweet, whatever it means, because they never asked me!
Finally, there is ACSYNT. There is 'something of the night' about that one. When I visited a NASA research center in the 1980s, I was shown a pile of fortran printouts and told it was Acsynt; but nobody was familiar with it and its originators already appeared lost in the mists of time. Subsequently, a graphical interface was bolted on top. It does pretty rotating 3D views of combat aircraft, but beyond its apparent military intent I've no idea about it.
So, if you seek to venture into the dark side, here are links to Darcorp, Raymer, Pace, Acsynt. May the force be with you.
Now, one might question my objectivity at this point! So maybe someone wants to arrange a fly-off: Say we all meet for a day in front of the customers, give presentations, then sit down and model a real aircraft completely from scratch, and see how far we get. Or maybe they'll put up reciprocal links to piano.aero.
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Is it possible to buy your data on just one aircraft?
Yes, you can now purchase Piano-X files individually.
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Do you do consultancy?
Please enquire directly, with a brief indication of your requirements.
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I see Piano can handle environmental emissions. How about noise?
At the moment there is no explicit feature for noise. However, the 'manoeuvre sequence' feature can readily produce very detailed outputs from any arbitrary LTO cycles you care to construct. This will give you tabulated histories of time / distance / altitude and thrust levels, which can then be used as input to an INM (integrated noise model) or similar footprint-producing tools.
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Is Piano easy to learn and use?
Yes, scarily so (as you may prefer not to let just anyone run it). How effectively and meaningfully you use it depends on your background experience in this field. You will quickly get a natural feel for its interactive philosophy. It's easy to set up a first design from scratch, as explained in the guide, or just experiment with the database. The system is designed to be played with. A 3-day familiarisation course will give you a chance to ask direct detailed questions in any specific areas you want to focus on.
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Is there anything you're not telling us about Piano?
Clearly you have run out of serious questions. You should definitely not look here.
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