forum.ww1aircraftmodels.com
WW1 Aircraft Modeling => WW1 Aircraft Information/Questions => Topic started by: ALBATROS1234 on July 10, 2015, 03:18:09 PM
-
i often study aircraft drawings.sometime to check certain dimension sometimes for scratch or modification projects. i often find discrepencies. i wonder what is the proper way to measure dimensions on a drawing. usually i start at the tip of the cowl and go to the far end of the rudder,or should i include the prop. what if theres a spinner? or is it from the tip of the cowl to the end of a/c structure? as in exclude the rudder? wings are easier just find the longest point right? does that include or take into account dihedryl? as in say a wing is supposed to be 7m span but theres a considerable dihedryl , is it the actual length of the wings or do you have to draw an imaginary right triangle from the lower connection of the wing to the tip and measure on a horizontal plane?its confusing? any ideas of the correct way, because i take actual dimensional data and divide by the scale 32,48 or 72 and it never matches up. sometimes closer than others. even with so called big boys of the aero drawing world does this happen. help!!!!!!
-
When I do my scratch builds I use plans that come from a book or from the net. The overall length of the aeroplane includes all extremities, the furtherest point on the rudder to the most forward point up front, this might be the front of the propeller, the tip of the spinner or any landing skids that protrude past the propeller. The wing span is just that, the total width across the wings. The best way to take dihedral into account is to measure the wings from the centre line to the wing tip taken from the front elevation, this will negate the dihedralm as you are measuring the wing as seen from the front, double the measurement to obtain total wingspan. Same applies for the undercarriage struts, measure them from the front which will take into account the splay of the legs. It can get confusing at times but a little bit of pre-planning can save a lot of headaches later on.
Des.
-
Correct me if I am wrong but I do not think wingspan measurement includes balance type ailerons if they extend past the wing tips. Seems that way on Fokker drawings.
-
To the hopelessly dopey, like me, it's a minefield. Due to my own carelessness last year, I found that I needed to replace struts that ran from tight in at the wing root up to the wing. I measured with such precision from my Datafile, but stupidly used the side rather than the front elevation and thereby failed to take count of the angle at which the struts were set and it left them far too short.
Best wishes
Nigel
-
I used to scale the drawings up and down with a copier until.... I discovered that the wings of my hanriot in 1/32 scale were completely off.
One thing to check is at least the inner consistency among the views.
If you take some drawings of the last generation sometimes there is a discrepancy of nearly an inch between the front view and the plan view due to differential scalinig betweeen the two directions during the printing process.
You can correct this distorsion importing the drawings in a graphic package and applying a differential scaling.
-
Ditto to Ermeio. When I prepare three view drawings for creating 3D models I superimpose the three views on separate layers in Photoshop. Then i nudge, rotate and scale until the basic dimensions of the major components agree -- but there are always discrepancies that require fudging.
-
Wingspan is the distance on a straight line from wingtip to wingtip. Measure it from above. It has no relation to the actual length of the wings themselves. As you stated, dihedral will lessen the apparent wing length if viewed from above so if it's wing length you require, you need to measure that from the front!
Ian
-
thanks guys, this is helpful. i havent ever considered that reducing/enlargeing may reduce or enlarge in diff proportions in the x and y axis. i just find always issues for instance i was thinking on the sikorsky s-16,using the fmp sikorsky s-16 book as a ref i found there were diff models the 154,155,156 then there was the s-16ser then the s-16a and s-16(3) the book shows drawings for the (ser) but changing these to 1/32 if i got the wingspan right the fuselage was off,even if i measured with or without the prop etc. so i goto my other source "imperial russian air service" book and theres drawings of what is called a s-16,it looks like sn 154 from the other book but those measurements are further off and the dimensions given earlier in the book are different and these drawings were by ian stair who is known to have done quite a few drawings considered accurate.
this isnt the first time this has happened,its a nightmare. i compare given dimensions with drawings in windsock datafiles as well as many other reputable reference sources and i rarely works out right. that why i wanted to see what is the proper way to measure.
-
its a miracle any model company ever gets anything remotely right. do they? drawing rarely barely sometimes kinda match models. if they do is it even right? whats right? are the drawings in our refs this skewed. should you just get one dimension close and then go with that? if so everything we do is out of scale in some way.
-
It's not that difficult to get an accurate measurement for a model if there is an actual full size aircraft still in existence. Many model companies will measure and photograph a real aircraft as well as use actual builders plans. But this data isn't always available so it is approximated from the varied sources, hence the discrepancies. Newer models such as the Airfix kits are created by first scanning the aircraft and creating a computer model that is accurate to less that a millimeter. I'm sure Wingnuts kits are developed using the same plans that TVAL uses to build their reproductions.
George
-
It's not that difficult to get an accurate measurement for a model if there is an actual full size aircraft still in existence. Many model companies will measure and photograph a real aircraft as well as use actual builders plans. But this data isn't always available so it is approximated from the varied sources, hence the discrepancies. Newer models such as the Airfix kits are created by first scanning the aircraft and creating a computer model that is accurate to less that a millimeter. I'm sure Wingnuts kits are developed using the same plans that TVAL uses to build their reproductions.
George
Do you have a 3D scanner to scan real aircraft?
And if you do have, do you have the historic aircraft at hand?
And if you have them, do they let you measure them?
The "it is not that difficult" is rather questionable.
You can measure aircraft with the right instruments, but probably you won't reach the needed accuracy.
Photos can help here.
I measured a bleriot, and a spad VII some thirty years ago and a gabardini replica three years ago, but I was lucky to find fellows modellers mounting the guard there.
Last week I went to the Italian Aviation museum, but the climate was so hot that I had to go out in half a hour before my brain evaporates...
You will find any sort of difficulties in measuring aircraft...
Moreover, many designers work from their home, and so it is mostly a research work not an empirical work...
-
I was referring to big model companies using scanners. Scott stated that it's a miracle any model company gets anything remotely right. Of course the bigger model companies have advantages we don't have. We often have to rely on other people's measurements and photos. Ultimately, all models are an approximation because of scale tolerances and material thicknesses, etc. But I do think with the available info on the net and the aircraft in museums it is possible to get reasonable accuracy. Take, for example, the Mercedes D.III engine parts Bo has created for 3d printing. He's used measurements and photos taken from actual engines to make what is probably now the most accurate versions available, and he's not a big company with deep pockets. He's an independent modeler like the rest of us.
But, ok, getting proper measurements is not always the easiest thing to do, but it's not a "miracle". :D
George
-
well said george
-
I was referring to big model companies using scanners. Scott stated that it's a miracle any model company gets anything remotely right. Of course the bigger model companies have advantages we don't have. We often have to rely on other people's measurements and photos. Ultimately, all models are an approximation because of scale tolerances and material thicknesses, etc. But I do think with the available info on the net and the aircraft in museums it is possible to get reasonable accuracy. Take, for example, the Mercedes D.III engine parts Bo has created for 3d printing. He's used measurements and photos taken from actual engines to make what is probably now the most accurate versions available, and he's not a big company with deep pockets. He's an independent modeler like the rest of us.
But, ok, getting proper measurements is not always the easiest thing to do, but it's not a "miracle". :D
George
Yes, George, but like most of us they go the easy way, unless they are headed by modellers and have museums at hand, like WNW eduard and airfix.
There is still a gap around to fill before new technologies can enter mass modelling market.
Your position is not different from mine. Bo took plans, photos and measurements and produced 3D models for printing.
Going to measure on site would cost much more and it wouldn't have been sustainable for a single person or organization.
We must not forget that modelling research is a collective effort, like any kind of research and this is the added value of communities like this one.
Like Des said, it is a learning experience.
-
You and Des are right, Ermeio, it is a learning experience. I think a lot of us here really like that aspect of this hobby. We're not only modelers, but history buffs too. Is great that there is a collective community here that understands and appreciates doing things well and trying to get things as accurate as possible. Maybe it's not always attainable, but with our group, we are at least striving to improve the overall quality. Our knowledge base keeps growing and growing. I couldn't build half of what I model without the help of the people on this forum and the information they share.
George
-
A great discussion. I have to say although I try very hard, I am more than a little uncomfortable having my stuff being held up as a paragon of scale accuracy. :o :)
Ermeio is 100% right that my efforts are completely dependent on others who did the original research! measuring, drawing, etc.
Moreover I cannot claim my parts are perfect 1:32 scale replicas of the originals. For one thing the parts they are intended to replace or supplement are not 100% true scale -- usually slightly undersized for well known reasons. Second, there are all kinds of fudging that has to be done to get contradictory source info to resolve. Even in cases where very complete dimensional info is available there is still guesswork / interpretation / interpolation involved when it comes to things like fillet radii and so forth...
Cheers
-
Sorry, Bo, I didn't mean to make you uncomfortable. :-[
I guess, in the end, we're just doing are best to make a good looking model to our eyes. It's very subjective though and like I said, it's an approximation and we have to make certain compromises. :)
And now I'll just zip up my mouth. :-X ;D
George