Underpowered? overloaded.

[Igo kyu]

There were a lot of WW2 aircraft that were called underpowered, however it seems to me that that's letting off the designers too lightly. Really, the power source was more or less a given, and the designers should have based the design on the power that the engine they were going to use would produce.

I think that there's a pretty strong case to be made that what's called "underpowered" should usually be called "overloaded", or maybe even "overwinged".

[JacksonsGhost]

I see what you're saying Igo kyu. If a designer is given a certain powerplant to work with and they produce a design that is overweight for the powerplant you could say that their design is overloaded, and that may be their own silly fault.

However, in common aviation terms, if you are calling an aircraft underpowered or overloaded I believe those terms mean two different things. An overloaded aircraft is usually one which is operating above its design weight, or at least above its design weight for a given situation. In comparison, an underpowered aircraft is usually one which lacks performance at or below its design weight.

And for the latter case, the cause may well be, as you suggest, the fault of the designer. It may also be the fault of whoever insisted on adding extra weight/drag to their design prior to production. Or in some cases the engines that the airframes were designed for just didn't come up to expectations, but were used anyway until something better was available. And finally, use of the term underpowered can be a relative thing. What was considered reasonably powered at the beginning of a design process, may be considered underpowered compared to other aircraft by the time it reaches production.

Of course if you are flying an aircraft which is both underpowered and overloaded then just taking off and landing safely may be a challenge!

[Igo kyu]

Originally Posted by JacksonsGhost

I see what you're saying Igo kyu. If a designer is given a certain powerplant to work with and they produce a design that is overweight for the powerplant you could say that their design is overloaded, and that may be their own silly fault.

You are correct, that is what I'm talking about.

However, in common aviation terms, if you are calling an aircraft underpowered or overloaded I believe those terms mean two different things. An overloaded aircraft is usually one which is operating above its design weight, or at least above its design weight for a given situation. In comparison, an underpowered aircraft is usually one which lacks performance at or below its design weight.

Well, I get what you are saying with the latter, and "overloaded" may be a less than helpful word, but it seems to me that if the design was specified to use a particular powerplant, and is underpowered with that powerplant, the fault is in the design, not the powerplant.

And for the latter case, the cause may well be, as you suggest, the fault of the designer. It may also be the fault of whoever insisted on adding extra weight/drag to their design prior to production.

I am thinking that the case of people outside the designer adding extra constraints is part of the design process, the actual designer may have done the best they could with what they were given, but the design was faulty despite that.

Or in some cases the engines that the airframes were designed for just didn't come up to expectations, but were used anyway until something better was available.

There were certainly engines that did not reach their intended performance, I would not include aircraft afflicted with those among those I am talking about.

And finally, use of the term underpowered can be a relative thing. What was considered reasonably powered at the beginning of a design process, may be considered underpowered compared to other aircraft by the time it reaches production.

That is not what I'm talking about really, there is a trade-off between lift and speed, if you aim for too much speed you won't get enough lift, and vice versa which is really what I am interested in discussing. If an aircraft achives a reasonable speed considering it's powerplant, that's sort of good enough but a lot that flew early in the war didn't achieve that. It's probably more often a case of over optimistic specifications than designer incompetance, but there were a lot of slow heavy aircraft that could and should have been lighter and faster. Of course, sometimes speed wasn't important and time aloft was, and there were aircraft rightly optimised for that.

Of course if you are flying an aircraft which is both underpowered and overloaded then just taking off and landing safely may be a challenge!

Yep, though probably more taking off than landing.

[Jumoschwanz]

I don't see the point to this post. The military puts up specifications it wants for an aircraft, and then multiple manufacturers put a plane together to compete for the contract. The designers not only have to try and meet the specifications, they have to work around available materials and technology. On top of those obstacles there is always government corruption trying to give the contracts to manufacturers that do not always have the best aircraft designs.

With all that in mind, it is silly to fixate on a designer or engineer about the performance of an aircraft.

[Igo kyu]

Originally Posted by Jumoschwanz

I don't see the point to this post.

Thanks for making the response anyway.

The military puts up specifications it wants for an aircraft, and then multiple manufacturers put a plane together to compete for the contract.

In Britain it was the air ministry which supplied the specifications:

https://en.wikipedia.org/wiki/List_o...specifications

This is a partial list of the British Air Ministry (AM) specifications for aircraft. A specification stemmed from an Operational Requirement, abbreviated "OR", describing what the aircraft would be used for. This in turn led to the specification itself, e.g. a two-engined fighter with four machine guns. So for example, OR.40 for a heavy bomber led to Specification B.12/36. Aircraft manufacturers would be invited to present design proposals to the ministry, following which prototypes of one or more of the proposals might be ordered for evaluation. On very rare occasions, a manufacturer would design and build an aircraft using their own money as a "private venture" (PV). This would then be offered to the ministry for evaluation. If the aircraft generated interest in the ministry or RAF due to performance or some other combination of features then the ministry might well issue a specification based on the private venture aircraft.[1]

The designers not only have to try and meet the specifications, they have to work around available materials and technology. On top of those obstacles there is always government corruption trying to give the contracts to manufacturers that do not always have the best aircraft designs.

With all that in mind, it is silly to fixate on a designer or engineer about the performance of an aircraft.

Who else is responsible? There are problems, and compromises must be made, but in the end any particular engine can do so much and until it is redesigned no more. I'm not trying to put unfair blame on the 27th designer, but the top guy should know what's going on.

There were some outright silly designs in use at the start of the war, as well as some great ones. There were occasional aircraft that got to the prototype stage, and sometimes beyond that, and then failed.

It's fun sometimes to think of what might have been, we're all armchair generals in our own heads, I don't think there's anything wrong with that.