Vertipedia Notes


Vertipedia notes are brief descriptions of how and why Vertipedia works the way it does. Browse the complete list below, or search by key word or phrase using the quick seach box above.

What are Vertipedia Notes?

Vertipedia has been developed by a small team since the launch the project in Nov 2013. The purpose of the notes is to document and inform VFS members of the principles and processes used by Vertipedia. As always, the team does not claim to always have the best knowledge and where members have different views their feedback is welcomed. Note titles and descriptions are limited to 100 and 500 characters, respectively, to ensure that a note is concise and succinct.

Created 09/18/2018  |  Modified 06/08/2019

Compound terms

Compound terms in Vertipedia are only applied to helicopter and gyroplane VTOL types (with one exception). This follows the accepted practice within the industry. For gyroplanes, only the lift compound term is applied to gyroplanes with wings - thrust compounding is inherent in that class of rotorcraft. One other aircraft that is marked as having lift compounding is the Herrick HV-2 Convertaplane, which could effectively become an autogyro when the fixed wing was allowed to rotate in flight.

Created 09/18/2018  |  Modified 06/08/2019

First flight milestones

First flight milestones are recorded in Vertipedia because they provide a very tangible and unambiguous record of progress in VTOL aircraft design and development. Wherever possible, untethered flights are used as the common denominator as they represent a baseline that all aircraft have to achieve. Events such as 'roll-outs', for example, are not included because they are usually marketing driven events rather than a real measure of development progress or achievement.

Created 09/18/2018  |  Modified 06/08/2019

What aircraft can be added into Vertipedia?

Vertipedia has been built specifically to be a source of reference information. It is not a vehicle for promotional or marketing information. The Vertipedia team decided that limiting the data to aircraft that have actually flown would be an unambiguous way to limit the scope of the data included. There is also a minimum gross weight limit of 500lb. There are many important historical projects that never flew but there has to be some clear, defining rule about what to include or not.


Created 09/18/2018  |  Modified 09/29/2018

Images for prototype aircraft

Vertipedia attempts to provide detailed, specific information about a particular aircraft rather than generic information for the Type. Many prototype aircraft have features that change during development into a production standard and no prior knowledge is assumed of these changes. Because of this, if an image for a verifiable prototype is not available then, normally, no image will be displayed. The Type page shows links to images of from the series.

Created 09/18/2018  |  Modified 02/03/2019

Image attribution

Attribution of images covers both the owner of an image and the terms under which it can be used. Vertipedia aims to maintain the professional standards normally associated with VFS products. Many web sites use images that have been copied from other sites without proper attribution. This may be a breach of copyright but, more importantly, does not respect the author and their wishes regarding use of the work. This is why we ask that all images used in Vertipedia must carry proper attribution.

Created 09/18/2018

Gyrodynes versus compound/hybrid helicopters

A gyrodyne is strictly a rotorcraft that can be powered for take-off and landing with the rotor disk being level to the flight path in cruising flight, which is  similar to how a compound/hybrid helicopter works (differences are primarily in the rotor disk angle in cruise) . To avoid difficulties for users in classifying the two types, Gyrodynes are classed as compound helicopters (with thrust compounding, possibly lift compounding) in Vertipedia.

Created 09/18/2018  |  Modified 10/10/2018

Why include multiple companies for designer or manufacturer for an aircraft?

Vertipedia aims to provide an accurate historical record for each aircraft. Many companies change over time as they change name, merge or get taken over. Many times the company associated with an aircraft is only the short name (normally the brand name), which tends to get preserved (e.g. Bell). However, the actual company behind the brand name may change and we try to ensure that these details are properly captured and preserved.

Created 09/18/2018  |  Modified 06/08/2019

Classification of milestones

Milestones are classified by the type and importance of the event. The type of event provides an objective view of the context for the event whist the importance is a subjective view its importance to VTOL history. Both are determined by the contributors to Vertipedia but the latter will always be subject to discussion and debate, which is welcomed through direct participation in Vertipedia or by contacting the Vertipedia team.

Created 09/18/2018

Vertipedia versus Wikipedia

Vertipedia and Wikipedia are different tools - both have useful roles. Vertipedia is built upon relational database principles, which allows data relationships to be developed automatically and reduces the need for a large number of contributors. Vertipedia provides access to all VFS resources (documents, etc.) that are not readily available elsewhere. Vertipedia integrates all the major elements of VTOL aircraft reference data (e.g. milestones, biographies, aircraft) together, which cannot easily be done using other tools like Wikipedia.

Created 09/18/2018  |  Modified 11/26/2018

Engines and power ratings

Vertipedia enables the rating structure for an engine to be defined. The rated power for an engine is assumed to equal the maximum power, under non-emergency conditions - normally the Take-off power. All engine powers are uninstalled at SL ISA conditions. Many engines are de-rated or limited for specific aircraft installations. Where this is known, the engine is described using the name template '[Engine designation] (as used on [Aircraft ABC])'. Gearbox torque limits are not currently available.

Created 09/18/2018  |  Modified 03/12/2019

Adding Aircraft Images into Vertipedia

Images can be added directly into Vertipedia or from the VFS Gallery using the Contributor functions. Adding images from the Gallery is the easier option by far. It is important that a contributor only uses images for the exact model of aircraft in question (e.g. Bell AH-1Z rather than a generic image of an AH-1). The images section for a specific aircraft aims to provide a complete view of the key characteristics of the aircraft and there is no limit to the number of images that can be used.

Created 09/18/2018  |  Modified 06/06/2019

Linking milestones and biographies

A key feature of Vertipedia is making connections between important events in VTOL history and the people who helped to create them. Wherever possible, we attempt to highlight the most direct connection (e.g. the pilot or crew of a first flight). Some connections are more subtle but still worth recording (e.g. key people involved in creating a concept, theory or design). These connections will always be open to debate so we welcome feedback on how these connections can be improved.

Created 09/18/2018

Using the Feedback system

Vertipedia has an in-built system for providing feedback (simply select the Feedback menu option). This enables users to tell the Vertipedia team about any issue including data errors, problems using the database or suggestions for improvements. When you provide feedback the system tracks which page you are on. Your email address is requested so that we can give you a response to your query. We encourage you to use the system to help us make Vertipedia better.

Created 09/18/2018

Aircraft Types, Variants and Versions

The aircraft module in Vertipedia assumes a Type/Variant/Version structure for aircraft from the same family (or series). In many large programs the manufacturer uses this type of structure (possibly using different terms) to develop a range of different versions for different customers. A version normally defines an aircraft for a specific operator. A specific aircraft can only be assigned to one Type and Variant. Aircraft do not have to be assigned to a Type or Variant.

Created 09/18/2018  |  Modified 12/04/2018

Aircraft searches using the Filtered search

The Filtered search finds aircraft by characteristic or through a search term input at the top right of the window. If the user searches by characteristic, each selected characteristic acts as an additional filter to the others. The results appear automatically after each filter is selected. When using the text search the user should enter the minimum number of characters to maximize the probability of locating an aircraft. The required aircraft can then be selected from the list of results.

Created 09/18/2018

Aircraft dimensions

The layout section for an aircraft includes both 'Overall' and 'Airframe' dimensions. The overall dimensions define the 'box' the rotorcraft would fit into with rotors turning. The airframe dimensions are those of the airframe structure alone minus the rotors (with a few exceptions stated in the aircraft notes). In both cases the aircraft is assumed to be ready for flight. If the aircraft can be folded, these external dimensions are not currently shown.

Created 09/18/2018  |  Modified 09/27/2018

Why not use just typical data for a Type of aircraft?

Other databases (e.g. Wikipedia) tend to show typical data for one aircraft deemed to be representative of a Type. Whilst this can be informative, it implies that all other aircraft are very similar, which may or may not be true. Vertpedia allows users to enter data for any aircraft in a Type series. This is particularly useful when there are significant, or noteworthy, differences between individual aircraft within the Type and avoids someone having to decide what is representative.

Created 09/18/2018  |  Modified 11/16/2018

Why can't I find a specific aircraft in Vertipedia?

Vertipedia is being developed by a very small team of VFS members who volunteer their time to help make Vertipedia a valuable industry resource. The amount of data in Vertipedia has grown rapidly, but we always need new contributors. If you see something that you feel should be in Vertipedia, but isn't there, why not get involved and join our team?

Created 10/01/2018  |  Modified 06/08/2019

Data accuracy and completeness

Similar to most databases, Vertipedia will never be complete. The data available represents a 'snap-shot' in time. Users should always consider other resources, particularly high quality references (e.g. books, archival material, etc.) if they want to ensure the highest accuracy. Vertipedia provides a good starting point for such research but the VFS can never state, categorically, that the data for a particular subject is the most accurate or complete.

Created 10/09/2018  |  Modified 10/09/2018


Vertipedia includes a glossary, available from the built-in menus. Although most terms used in the database have a well understood definition there is always the possibility that a term used might be interpreted differently by various users from a range of backgrounds and experience. We encourage all users to use the glossary to avoid any possible confusion. Please use the Feedback option if you require any clarification or believe the Glossary should be changed in any way.

Created 10/09/2018  |  Modified 10/10/2018

Company names associated with aircraft

A number of aircraft carry associated company names that may seem odd at first. On pages related to specific aircraft the company is that of the latest/last manufacturer. On the Type page the company name is the company with the over-arching responsibility for the design of this family of aircraft (this can change over time). This approach ensures that both individual manufacturing and overall design responsibilities are properly recognized.

Created 10/10/2018

Vertipedia training requirements

Vertipedia has been designed from the outset to minimize the need for any specific training for users to either access or contribute to the database. Contributing to Vertipedia is more demanding but this is related more to the interpretation of external data before adding it to the database rather than any complexity with adding/editing data. A user guide is available from the Vertipedia team on request. We are always grateful for feedback on how to improve the user experience.

Created 10/10/2018

Resource searches

The 'Find Resources' menu option is one of the most powerful features in Vertipedia. A user can construct simple, or more complex, searches (still being developed) of all VFS resources and many high quality external resources (e.g. NASA documents, US patents). The VFS resources covered include Forum Proceedings, Vertiflite articles, VFS web pages and Journal articles not normally available from other search engines.
The search algorithm used is quite sophisticated and will return many results close to the requested search.

Created 10/10/2018  |  Modified 06/11/2019


References are an essential part of a high quality technical database. The referencing system in Vertipedia was introduced early on but needs further development. References are available for most milestones (a small number were not properly referenced during early development). In future releases, references will be available for each entry (e.g. Aircraft, Biography, etc.) and references will be provided for each data point in the Aircraft and Powerplant modules.

Created 10/10/2018

Adding and editing data and information

Data and information can be added or edited in Vertipedia using the contributor functions on the desktop version only. A user can become a contributor on request to the VFS (Betty Chen or Randy Johnson). These functions require no special training. A User Guide is available from VFS on request. Existing data modules (e.g. configuration, main rotor, tail rotor, etc. can be re-used to minimize the data entry burden when creating a new aircraft. Aircraft can also be replicated where similar.

Created 10/21/2018  |  Modified 11/15/2018

Level of detail in entries

Vertipedia sometimes lacks detail supporting a particular entry. Primarily, this is because Vertipedia data is built using a 'top-down' approach where details are expanded over time. This allows us to more quickly capture breadth as well as depth of data. The depth of data is particularly related to the number of contributors. Please contact the Vertipedia team if you think that you can help.

Created 11/04/2018

Milestone dates

Wherever possible, the exact date of a milestone is provided. In some case, the exact date is not known and only the month and year are available. Wherever this is the case the last day of the month is used with a note in the description to say that the exact date is unknown. The last day of the month is used as a conservative estimate of the actual date of the event. In a few cases, there is conflicting data regarding the exact date and a note has been added to highlight the alternative date.

Created 11/12/2018  |  Modified 11/12/2018

Aircraft and Type resource searches

For each aircraft and Type there is an automated search of available resources (documents, etc.). In most cases these automated searches produce a range of useful results. In some case the results may include many that are not relevant. This is because the aircraft or Type designation includes a common word (e.g. Model). It is difficult to define an algorithm that will counter this issue. The user can always use the configurable search from the menu bar for better results.

Created 11/21/2018  |  Modified 02/12/2019

How are 'Featured Aircraft' chosen?

The 'Featured Aircraft' in Vertipedia is usually chosen to highight the depth of data that can be available for a particular aircraft. We try to choose an aircraft that should be interesting to a wide range of users of the database. To this end, we generally cycle between historic or current aircraft but we also occasionally highlight aircraft that may be of interest to a smaller community. We try to change the aircraft on a monthly basis but there is no set period.

Created 11/27/2018  |  Modified 11/28/2018

Aircraft designations

In Vertipedia an aircraft has both a primary and secondary designation. Normally, the primary designation will be the alphanumeric and the secondary designation will be the name (e.g. UH-60A Black Hawk). Not all aircraft follow this scheme. The primary designation should also be the part of the designation that an aircraft is normally known by (which might be a name), normally the operator given designation. An alternative designation can also be added (in brackets) (e.g. a company model name).

Created 12/06/2018

Countries for Biographies

Biographies have two fields, the country of birth and the country of primary activity (as people move during their career). The reason for includng both fields is to avoid the confusions that could occur if a single field 'Country' was included. The country of birth is a fact. The country of primary activity requires subjective assessment. The Vertipedia team has made an assessment for the country of primary activity but we welcome feedback if there is any disagreement.

Created 12/06/2018  |  Modified 12/06/2018

Map locations for milestones

The aim is to provide an exact location for each milestone in the database. In many cases this is not possible and all we can provide is the nearest possible, general location (usually a town instead of a specific location). The map view provided is normally chosen to provide detail of the location as well the general area to provide overall geographical context. We always welcome feedback on the accuracy of the map locations provided.

Created 12/10/2018

Birth date milestones of VTOL pioneers

Milestones for the year of birth of VTOL pioneers are not provided in Vertipeda, although they are shown in the relevant biography. The purpose of the display in 'Milestones by year' is to provide a simple, visual timeline of VTOL aircraft development from start to the present day. This timeline comes from the milestones in Vertipedia. Birth date milestones would distort this view as the people in question were developing their careers before achieving tangible milestones that are shown.

Created 02/03/2019

Milestone title format

The title of a milestone is meant to succinctly summarize the milestone. As such, the title generally follows the following format,
Description of event (related aircraft designation)
e.g. First helicopter shipboard take-off and landing (Flettner Fl 265 V4)
The inclusion of the aircraft designation is important to help in relating an aircraft to a milestone through the Contributor functions. The details of the event can then be included in the description of the milestone.

Created 02/03/2019  |  Modified 06/08/2019

Entering text data

When entering text into any of the text fields (these are distinguished by the editing functions toolbar at the top of the field) the user should not add an extra line break between paragraphs (a new paragraph is simply the next line after the a line break is entered). This is because the displayed text automatically adds an appropriate line spacing for display). If an extra line break is added on entry this will show as a double line spacing on display.

Created 02/13/2019

Titles for milestones

When creating a milestone that relates to an aircraft it is important to use the designation of the aircraft somewhere in the title e.g. Description of a milestone (Aircraft XYZ).

This then allows users to search for milestones related to a specific aircraft, when using the milestones search, as well as searching for specific events.

Created 02/20/2019  |  Modified 02/20/2019

Aircraft images

Images for aircraft appear in two sub-sections on an Aircraft page,
- Related VFS Resources
- Images
Although some of the images are repeated, the two sections serve different purposes. The first section aims to capture any image related to the aircraft, which could be aircraft, people, events, etc. The latter section only includes images selected specifically to highlight features of the aircraft.

Created 06/03/2019  |  Modified 06/04/2019