What constitutes an aircraft type?

[Stephen B]

 

I would like to ask for your opinions.

 

Reading a thread elsewhere which asks the question 'what have you flown in?' Set me thinking. What constitutes an aircraft type?

 

Clearly a Spitfire is not a Hurricane. But is a Spitfire mk22 the same aircraft type as Spitfire mk1?

 

Things are even more complicated if you look at the Airbus A320 or Boeing 737 families.

 

Someone suggested to me that it was a separate type if you needed a seperate type rating to fly it. But this throws up anomalies since the Boeing 757 and 767 had a common type rating.

 

What about licensed built aircraft that are modified to suit local conditions such as the Bucker Bestmann and the Egyptian built Gomhouria?

 

Is a DHC Beaver landplane the same type as it seaplane brethren?

 

How about aircraft which are extensively modified from another type, such as the Thruxton Jackeroo and Tiger Moth?

 

What about the Cessna 150  and 152?

 

And does all this really matter?

 

What are your opinions please?

Edited April 27, 2023 by Stephen B

[Dave Swindell]

50 minutes ago, Stephen B said:

 

Clearly a Spitfire is not a Hurricane. But is a Spitfire mk22 the same aircraft type as Spitfire mk1?

Depends who you're talking to and why

To the CAA both Spitfire and Hurricane are high powered, tail dragging low wing monoplane warbirds, but to Supermarine, the Sptifire Mk I was the Type 300, and the Spitfire Mk 22 was the Type 356.

[pigsty]

1 hour ago, Stephen B said:

Clearly a Spitfire is not a Hurricane. But is a Spitfire mk22 the same aircraft type as Spitfire mk1?

You've almost answered your own question there.  In one sense, a Spitfire is any aircraft so similar to another Spitfire that it can't be mistaken for a Hurricane.  Two Spitfires may have a lot of differences, but they're still Spitfires if you look at them and think, Spitfire.

 

And this also illustrates how arbitrary it all is.  Spitfires are famously the same length from the firewall to the rudder post, but almost nothing else is the same from one end of the range to the other.  Yet you can trace the evolution along that line, you know they were all designed by Supermarine, and so they must all be Spitfires.  Except that some ended up being called Spitefuls.  That raises the question, just how much change do you have to apply before you're forced to admit it's not the same thing any more?  And the answer is, it's different every time.  Look at the F-86: the radar-equipped version was originally ordered as the F-95, but became the F-86D to make it easier to get the orders through the system during the Korean War period.  So was it a new aircraft, or was it a swep-up version of the F-86A?  No-one knows.  An F-84F Thunderstreak isn't an F-84E Thunderjet, and the USAF reflected that in its supply chains and maintenance manuals - yet they're also just variants of the basic F-84 design.

 

Something similar happens with cars.  Motoring journalists are fond of claiming that the Toyota Corolla is the most popular car ever because millions of them have been sold.  They haven't.  Eight or nine cars that Toyota chose to call Corolla have sold millions between them, but the only thing common between the first and the latest is the number of wheels.  They share nothing at all when it comes to design and engineering.  It's marketing that gives the false impression of a single type soldiering on for decades - that, and others' carelessness.  You really notice how false it is when you spot that the latest Corolla replaced the Auris, which (a few versions back) replaced another Corolla.  Are we really going to believe that the new Corolla's sales figures extend the Corolla "legend" while all those Auris have to be ignored?

 

So I think the answer is, it depends.  Which leads me to your other question: nah, it doesn't matter.  It's a good philosophical exercise, though, like Theseus's Ship or Trigger's Broom, only more so.

[Giorgio N]

It is not easy to define what an aircraft type is without first defining the scope of the classification into different types. As mentioned in a previous reply, the USAF used the same F-84 designation for both a straight wing and a swept wing aircraft even these were quite different for the reason that it would have been easier to get funding for an improved variant of the same aircraft. At the same time the Regia Aeronautica named the Mc.202 and 205 as different aircraft types even if one was actually little more than a re-engined variant of the other.

That is the problem with official designations, they can vary or stay the same for the most diverse reasons, some of which may make sense from a technical point of view and some of which are related to administrative or budgetary or even PR decisions: when Northrop developed their F-20 this was initially named F-5G as of course it was an evolution of the existing F-5E and the company believed potential customers would have liked the idea of a modern variant of an aircraft they knew well (same reason why car names often stay the same). Later however they realised that to compete with other options on the market it would have been more useful to state that this was a new aircraft from a new generation, so they requested the F-20 designation to emphatize the modernity (first of the 20-series figthers etc.).

And these are only the official designations, then there are the various manufacturer internal designations that can vary even with relatively minor modifications!

 

As an enthusiast in general I personally tend to consider a particular aircraft a variant of something if this retains a certain degree of commonality in the main structural parts, at least at exterior level. So a Spitfire XIV to me is still a Spitfire as afterall retains the same fuselage and wing shape of the original Spitfire I. Even if actually the internal structure of both is quite different ! That is something we often forget, we consider for example the Mk.VIII and the Mk.IX as variants differing in details only while in reality the internal structure was quite different. That is something that muddies the waters even more.

For this reason I also consider the Macchi 202 and 205 as basically variants of the same design as both aircraft share most structural elements (so much that a number of 202s were converted in hybrid 202/205 with DB.605 engines).

That of course means I consider the F-84G and F-84F as different aircraft types since the main structural elements are different in both wings and fuselage...

I also consider the Kfir as different from a Mirage III, since while the two look very similar in reality the fuselage sections are quite different in several areas. And so on...

Speaking in modelling terms, if I can easily enough convert a type into another one by replacing only a few selected parts, I tend to consider one type as a variant of the other. If the number of parts to change and/or modify is beyond a certain threshold, I tend to view this as a different type.

 

My approach sounds simple but of course there are situations where it gets more difficult... one is the Spitfire Mk.22 mentioned above: is this a Spitfire or something else that retained the Spitfire name ? Clearly there are parts in common between this variant and the original Spitfire I (really most of the fuselage between firewall and tail) but at the same time other important parts are quite different. Mind, the Mk.21 was already considered different enough that a new name was proposed (Victor) but in the end the name Spitfire stuck. A new name was probably justified.

Similar problem with different results: are the differences between a Lancaster and a Lincoln more or less pronounced than the ones between a Spitfire Mk.I and a Mk.22 ? Probably they are of the same level, here however a new name was chosen and I personally would consider them separate types.

And then there are airliners and general aviation aircraft where things get even more confusing... really I feel that with some types here we have to talk from the start about "families" of aircraft as the number of variations on the same base design is such that the members at the extremes may end up being very different. This is why I tend to throw all the various Airbus 320 variants and derivatives into the same pot, to me they are members of a family with clear common aspects but also specific features in each member.

 

The Cessna 150 and 152 ? I don't know much about these types, my answer would be that if the 152 retained the main structural components of the 150 then it's a new variant, if the main parts are very different then it would be a new type.

[Alan P]

Aircraft type isn't the same thing as a type rating. The type is defined by the manufacturer series or model number. The type rating is decided by the certifying regulator and is subject to negotiation. 

 

The sharing of aircraft components, parts, engines and instrumentation etc don't necessarily make them different types, but large differences in handling, performance and flight characteristics might cause a manufacturer to issue a derivative as a separate type even though it may operate under a common type rating.

 

Very similar, simple piston engined aircraft aren't covered by individual type ratings but under class ratings, e.g. Cessna 150, 152 and 172 are flown under the Single-engine piston class rating, although in type terms the 152 is a derivative of the 150 type but the 172 is a different type under the 17 model classification vs the 15 of the smaller type.

 

And outside of regulatory requirements, air traffic separation rules and airspace usage fees, it probably doesn't matter!

[Slackbladder]

Having flown Cessna 150s, 152s and 172 these would all be considered the same type. I've also flown the float version of a 172 and obviously needed float plane training for this but once in the air it's the same aircraft. I've flown low wings as well such as the AA-5 Cheetah and PA-28s and they behave much the same, only the view is different due to the position of the wings obviously.

Edited April 27, 2023 by Slackbladder

[dov]

May I say:

Look at the flxing envelope! If this differs, it is a different type.

Logicaly many versions are different types!

Happy modelling 

[wellsprop]

4 hours ago, Dave Swindell said:

Depends who you're talking to and why

To the CAA both Spitfire and Hurricane are high powered, tail dragging low wing monoplane warbirds, but to Supermarine, the Sptifire Mk I was the Type 300, and the Spitfire Mk 22 was the Type 356.

 

I think this is the best answer you'll get! 

 

Unfortunately, there are types and there are also other types. There's really no definitive answer.

 

Engineering-wise, a type is any variant of a model. Flying-wise, a type is something sufficiently different to require extra training. Broader, a type is an all-encompassing term when only using a few categories to differentiate aircraft roles.

 

As an example,

 

A Pa28 Warrior III is a different engineering type to a Pa28 Warrior, but in the eyes of the licensing bodies they are both the same. However, a Pa28 Arrow is different to both of those in terms of licensing (complex with undercarriage and wobbly prop), but they are all the same type (general aviation) in a broader category. 

 

So in other words, a type is whatever you want it to be, depending on what you define a type as 🤔

[ckw]

 

4 hours ago, pigsty said:

You've almost answered your own question there.  In one sense, a Spitfire is any aircraft so similar to another Spitfire that it can't be mistaken for a Hurricane.  Two Spitfires may have a lot of differences, but they're still Spitfires if you look at them and think, Spitfire.

 

I would say that the variations between a Seafire and equivalent mark Spitfire are much less that that between an early or late mark Spitfire. I imagine the Spitfire name was retained for so long in part for PR purposes. 

 

But for my purposes (i.e, whether to add a type to my collection), I let someone else worry about it and defer to the listing of types according to my preferred reference books.

 

Cheers

 

Colin