Was "Lofting" used in German Aircraft design?

[G Sting]

Was "Lofting" used in German Aircraft design? ... or any other country during WWI? If so, what aircraft companies used it?

From what I understand Lofting came from the ship building industry, first.
One definition: Lofting is the process of drawing the hull lines full size from the designer’s scale drawings. The intersections of the contours of various horizontal and vertical sections are measured from an imaginary “base line” using an architect’s scale. These junctions are then laid out, point by point, in their full size.

Many thanks.

[Douglas7]

I know Jimmy Wedell of the Wedell-Willams racers of the 30;s did such I see no reason why Aircraft designers of WW1 didn't do the same. I can't think of the book from which I read that...

[kristjanr]

Originally Posted by G Sting

Was "Lofting" used in German Aircraft design? ... or any other country during WWI? If so, what aircraft companies used it?

From what I understand Lofting came from the ship building industry, first.
One definition: Lofting is the process of drawing the hull lines full size from the designer’s scale drawings. The intersections of the contours of various horizontal and vertical sections are measured from an imaginary “base line” using an architect’s scale. These junctions are then laid out, point by point, in their full size.

Many thanks.

Some of them probably did, but aircraft design in WWI differed from company to company. Some companies used a rigorous engineering process while others did design work by the seat of their pants. Some manufcturers didn't even use drawings. Apparently the first proper drawings of the Fokker D.VII were made by Albatros who took a sample airframe and made drawings by measuring it up, which would be the reverse of the process you described.

[HoHun]

Hi Kristjan,

>Apparently the first proper drawings of the Fokker D.VII were made by Albatros who took a sample airframe and made drawings by measuring it up, which would be the reverse of the process you described.

Karlhein Kens and Hanns Müller describe this in a bit more detail in "Die Flugzeuge des ersten Weltkrieges 1914 - 1918":

"But starting up licence production was not as friction-free as the IdFlieg had hoped. At a time when many aircraft works still drew their designs in natural size on the floors and walls of their shops to transfer the measurements with a folding rule, no factory drawings existed at Fokker's either. His design office employed the following scheme: The design was drawn to a scale of 1:100 on millimeter grid sheets and the measurements required for production immediately transferred to the workpiece. Albatros had no choice but no purchase a D.VII from Fokker, dismantle it and prepare drawings after measuring the components. As a result, frontline units had to keep seperate stores of replacement parts for the D.VII, because the parts differed according to the factory of origin."

I have to admit I don't fully understand the processes as described, but at least the paragraph mentions lofting ...

Regards,

Henning (HoHun)

[kristjanr]

Originally Posted by HoHun

Hi Kristjan,

>Apparently the first proper drawings of the Fokker D.VII were made by Albatros who took a sample airframe and made drawings by measuring it up, which would be the reverse of the process you described.

Karlhein Kens and Hanns Müller describe this in a bit more detail in "Die Flugzeuge des ersten Weltkrieges 1914 - 1918":

"But starting up licence production was not as friction-free as the IdFlieg had hoped. At a time when many aircraft works still drew their designs in natural size on the floors and walls of their shops to transfer the measurements with a folding rule, no factory drawings existed at Fokker's either. His design office employed the following scheme: The design was drawn to a scale of 1:100 on millimeter grid sheets and the measurements required for production immediately transferred to the workpiece. Albatros had no choice but no purchase a D.VII from Fokker, dismantle it and prepare drawings after measuring the components. As a result, frontline units had to keep seperate stores of replacement parts for the D.VII, because the parts differed according to the factory of origin."

I have to admit I don't fully understand the processes as described, but at least the paragraph mentions lofting ...

Regards,

Henning (HoHun)

This is interesting, not just because of the technical details but because I didn't know that parts were not interchangeable between Albatros and Fokker built D.VII fighters. Not that I'm surprised, the Fokker company in general seems to have had the worst kind of issues with quality control and it's these kind of details that give an insight into why that was. Albatros may have been the big bad bully of the German aircraft industry but at least they had a proper engineering and manufacturing culture.

[G Sting]

Originally Posted by kristjanr

Some of them probably did, but aircraft design in WWI differed from company to company. Some companies used a rigorous engineering process while others did design work by the seat of their pants. Some manufcturers didn't even use drawings. Apparently the first proper drawings of the Fokker D.VII were made by Albatros who took a sample airframe and made drawings by measuring it up, which would be the reverse of the process you described.

kristjanr, this is very interesting. Thank you. Here, we might say that the aircraft designers were literally "winging it." (pun intended)

Joke aside (sorry, I couldn't resist ), it appears by your statement that at least Albatros used the process of lofting their designs before going to full scale mock-up or build... if I understand correctly.

"But starting up licence production was not as friction-free as the IdFlieg had hoped. At a time when many aircraft works still drew their designs in natural size on the floors and walls of their shops to transfer the measurements with a folding rule, no factory drawings existed at Fokker's either. His design office employed the following scheme: The design was drawn to a scale of 1:100 on millimeter grid sheets and the measurements required for production immediately transferred to the workpiece. Albatros had no choice but no purchase a D.VII from Fokker, dismantle it and prepare drawings after measuring the components. As a result, frontline units had to keep seperate stores of replacement parts for the D.VII, because the parts differed according to the factory of origin."

HoHun, thank you. The second sentence appears to use the process of lofting... as I understand it. (I am still trying to understand the lofting process as well... maybe a modeler can help us here.) From what I understand the lofting process came from the boat industry. Link that explains it some.

It would definitely be interesting if anyone has a drawing of an Albatros or other German aircraft with the plane, profile, or frames view... or even a photo of maybe the Albatros design process in action... if there are any around.

regards,
Mike G.
"G-Sting"

[kristjanr]

Originally Posted by G Sting

kristjanr, this is very interesting. Thank you. Here, we might say that the aircraft designers were literally "winging it." (pun intended)

Joke aside (sorry, I couldn't resist ), it appears by your statement that at least Albatros used the process of lofting their designs before going to full scale mock-up or build... if I understand correctly.

Well, lets just say that the design shop and production facility at Albatros seems to have been an environment where modern the aircraft designers and engineers who designed the F-22 and Eurofighter would feel a whole lot more at home than at Fokker. Albatros seems to have had a more formal engineering culture where drawings were an integral part of the design and production process. Mind you for all their engineering professionalism Albatros still had QA poblems since their D.III/V/Va fighters suffered from wing failures as is well known. And it really was a QA issue because Albatros fighters license built in Astria-Hungary did not suffer from this weakness.

[John McKenzie]

The answer to this cannot generalise , as lofting / multi sectional drawing is carried out ONLY for a specific reasons where it is deemed necessary "....in order to convey the relevant 3 D information to the shop floor ".
Although in certain works , ex-boat builders /woodworkers might be employed in manufacture , this is not to say that the designers or their draughting methods came from that industry also ,..in fact much engineering drawing practice came down through the infant automobile & those from locomotive practices .

Basicly , any flowing Irregular , double curvature surface will be described on a drawing by " lofting" practice ....This is simply "decribing the part in a series of grid sections " , in the 3 axis , with dimensions tabulated , simply in order more to keep the drawing Clear & free of confusion .
The draughtsman will use a variety of " splines " at his disposal , to create a flowing curve between specific points .

2 dimensional Airfoil/Rib sections ( often drawn at 1/2 Fullsize) , are normally shown with the offsets given against the dm lines ...the full size template being created from these on the shop floor ....Same with fus. bulkheads , though if of a varying curve , may be more easily tabulated as offsets horiz'ly & vertically .
Structural members are drawn in convensional 3 or more views with Section drawings as required .

LOFTING would apply only to any drawing that describes a 3 dimensional double curvature surface , such as Ally' or cold moulded pannel work ....whether this is applied to a nose shell , for example the FE2b or to the Fuselage shape for the plug for a Pfalz machine .
In each case the purpose is simply to ensure that the full size mould / egg crate jig , or whatever , that is produced on the shop floor as a prototype ,... is an exact full size version of that which was envisaged by the draughtsman , drawn in (often) a more practical reduced scale .

For the draughtsman to create drawings for a Pfalz fuselage at Full Size , would mean him being far too close to see that the lines were Fair .
Thus the primary drawing would be drawn initially at reduced scale ,..( 1/10 or 1/5 scale if metric , or prob 1/12, 1/8 , 1/6 or 1/4 if Imperial ) & then perhaps , dependant on size , transverse sections might be drawn full size in the drawing office ....OR this work might probably be left to the prototype shop floor tool room .

Examples where this would have been employed would be all streamlined Pfalz , Roland , Hawa & some Albatross fuselages etc....Along with smaller Ally' panel components or wooden cold mouldings on other machines as stated above .

The prototype Plug , as produced from the ( scaled up on shop floor to FS ) , lofted (drawn) lines , would be corrected for fairness by use of Splines , skill & "eye" & then all other production plugs would be made to these dimensions .
The outline profiles for the bulkheads frames would then be transfered at the appropriate locations to templates & the prototype drawings ammended as necessary .
.................................................. .........

Regarding Fokker ,....... or ANY manufactured machine of "Other than streamlined cold moulded, lap strake or other similar construction ",...there is NO NEED OR RELEVANCE to the use of LOFTED LINES .

If I remember , in a letter from Platz , Fokker design ( prototype) drawings such as rib profiles , were done on squared paper (sic) , at 1/2 scale , while others such as fuselages might often be at 1/10 scale for ease of transfer in the prototype shop to full size welding jig boards .
Production drawings eg, Assemblys etc. were done in the larger 1/5 or 1/2 or full scale .
There are some existant Fokker drawings that certainly pre-date the DVII , that are proper engineering drawings .

The Idea of Fokker draughtsmen doing drawings at 1/100 scale is just too silly.

Contrary to the myths still perpetrated , that surround that firm & its personnel ( intentional or not & by whom !) , Fokker did employ competent Engineers & Design draughtsmen ,.... rather than " Welder -- becomes genious designer " ....but that's another story !.

John M

[G Sting]

John M,

Very good, sir. Thank you for the detailed explanation.

If I remember, in a letter from Platz , Fokker design (prototype) drawings such as rib profiles, were done on squared paper (sic), at 1/2 scale, while others such as fuselages might often be at 1/10 scale for ease of transfer in the prototype shop to full size welding jig boards. Production drawings eg, Assemblys etc. were done in the larger 1/5 or 1/2 or full scale. There are some existant Fokker drawings that certainly pre-date the DVII , that are proper engineering drawings .

It would be nice to see maybe an example of a sub-scale production drawing from Fokker and/or Albatros. But maybe this is already published in a book or article? If so, can someone steer me in the right direction?

[Maxim08]

Hohun et al,

It is with some surprise that I read your quote from Karlhein Kens and Hanns Müller regarding separate stores of parts for D VIIs from differing manufacturers. My concern is that the authors may have taken some unattributed (in this thread) comment and applied it in a broader sense than was originally intended.

The Knowlton D VII (everyone must be getting tired of me referring to this) has control surfaces, struts, cowls and wings with eight (8) different serial numbers from the three manufacturers. This would seem to go against the non-interchangeability statement.

I do know that panels, fueling vavle assemblies, engines and components were undergoing running changes during the short life of this aircraft model. Perhaps this is what is being referred to?

Regards
John