Large Model Association Forum

Dear All

I have a request for any forum member who is a wiz with CAD.

I’ve been thinking and planning for a year or so about a project I’d like to do in retirement, still a few years off.

I have several sheets of plans for a Wittman D-12 Bonzo. It was originally built in 1934 by Steve Wittman and was a successful pylon racer. There are a couple of variants between 1937-38.

The most accurate plans I have are from the total refurbishment and rebuild from 1984. These show a very detailed drawing of all the main components, wing profile and scale.

The wing span was 17’2” , fuselage 22’ 2”on the renovation ( original dimensions ). A 1/2 scale model would be ideal.

Would anyone be willing to draw up a set of building plans, calculate the projected weight and suggest an engine size?

I would pay for the time involved. All the plans I have I would gladly copy and they would be yours to keep.I have some pictures I’ve dug off the internet and a photo of the most detailed plans. I shall post these later when I’ve reduced the size

http://www.airracinghistory.freeola.com ... 0Bonzo.htm

Spoken to all the usual people who make kits, no one can help. I’m hoping now to enlarge the 3 view drawings and take it from there.

No one with CAD ??

Cad software is free, and 2D will be easier to learn than 3D for making a model drawing.

https://nanocad.com/products/nanoCAD/

A rough estimate of my time to do some cad drawing came out at £12,000 (no vat) which is probably a bit spendy for a model plane.

Cheers Rob!

I’ve decided to see if I can get the 3 view plan blown up to 1/3 scale and take it from there.

I have a good contact who can enlarge the plan for you, does a really good job.

Give me a call
07810207875

If the CAD is being used to draw components, there's no need to blow up the plans, as they can be imported into the initial CAD drawing at any physical dimension and then the scale set by defining two points a known distance apart. This might be the actual length of the full-size aircraft, and then scaled to the required scale; or, a known distance on the model.

Either way, all that's required is a good high resolution scan of the image, the physical size of the image is basically immaterial provided the resolution is good enough. I would suggest somewhere north of 1200 dpi would suffice for most purposes. A4 scans would very likely be adequate provided the lines are suitably thin. Even if they're not, one can interpolate mid-thickness and obtain consistent results.

I am using a similar technique to construct the required curvatures of geodetic channel on my Wellington project, from basic side top and end elevations, by first generating an accurate 3d fuselage, then slicing it at 45 degrees, then using these slices as templates for curving the geodetic channel at each station. (somewhat simplified). If I haven't made a "Horlix" of it, it should result in a nice Wellington fuselage again when assembled!

Just wanted forum viewers to know Tim has come to the rescue. Thanks Tim

No problem. Any luck sourcing that high res scan?

Yes! I’m waiting for the new plans to arrive from the States. Then I can scan and send them on. Sorry it’s taking a while. I’m in the hands of others but it is in the pipeline

Recent message from Paul
“
Yeah, Peter. Sorry to keep you in the dark. Work went from zero to 60 in the last month.


The plans are at a copy place getting duplicated so that I don’t screw up the originals. I took them last Friday and in theory they’ll be done tomorrow. I should be able to send you copies of the original plates by the end of the week.

It may not be so useful to you, but I am also having a friend convert the plans to CAD so that in the future, I can just plot the drawing(s) or send out an electronic version. That, however, will take a couple weeks as she’s doing it as a favor.

Hope you’re well and safe, and I’ll send you tracking details soon.

PJS
“