Many times people get frustrated with performin' t' various mathematical functions needed t' scale down images o' real rockets and missiles. With t' correct software, t' task is quite easy.

Although t' majority o' builders probably wont have direct access t' t' required software, most o' us can use some creative resources t' find somebody that could spend a few minutes formattin' t' image for you.

Additionally, with some additional steps, these tasks can be performed with some low-end shareware or "paint" programs. Arrr! Blimey! My instructions will be based on usin' AutoCAD 2006 based program called Architectural Desktop. Begad! Blimey! Again, t' same techniques can be employed by many other programs.

Step 1: Insert t' Image

For this example, me bucko, I’m goin' t' scale down web-based images o' a Raytheon RIM-66 Standard missile. Begad! Images and scale data for this was very easy t' find usin' Google. With t' best image and a few key dimensions, I can get started.

A new drawin' is created in AutoCAD, shiver me timbers, and t' image is inserted usin' "image manager". Don’t worry about a scale factor yet. Avast, me proud beauty! Be sure your "image frame" is left on; otherwise changin' t' scale will be impossible.

T' RIM-66 is 14’-8" long, and 1’-1 ½" diameter. Draw a rectangle this size above t' image. Begad! Now, grab a corner grip o' t' image and stretch it t' about t' right size. Begad! Don’t worry about bein' exact. Avast, me proud beauty! Just close will be fine. Ya scallywag!

Step 2: Scale t' image t' "real life"

Draw a straight line from t' tip o' t' nosecone t' t' back o' t' rocket. You may need t' do some research t' determine what t' data considers "length". Query t' line you have drawn for its "X delta" or length. Now we can do our math.

Convertin' t' inches, me bucko, 14’-8" is 176 inches. Ahoy! Our line measures 172 3/8" inches. Avast! So divide 176/172.375 t' give a correction factor o' 1.0210.

Now scale t' line and image by this number. Avast, me proud beauty! Blimey! Query t' line again. It should be very close t' 176. Some roundin' error may occur. Ya scallywag! Blimey! Now draw a line across t' diameter o' t' rocket. Avast, me proud beauty! Blimey! Query it. It should be very close t' 13 ½". Don’t be alarmed if it is not. Arrr! Blimey! Most photographs will have some distortion in their axis relationships. Begad! Blimey! If you have Photoshop or similar raster imagin' software available, you may chose t' correct t' image t' a proper ratio.

If you have a significant error in you diameter measurement, me bucko, you may want t' consider usin' t' scale correction method t' get this dimension correct. Ahoy! Blimey! Be aware that doin' this will alter t' length! Blimey! Unless you correct t' raster image, one dimension will be wrong!

Step 3: Chose your scale

Now its time t' decide what scale your rocket will be. Aye aye! This is almost always determined by available body tube size. Typical outside diameter Estes body tube sizes are shown below:

• BT-5 .544"
• BT-20 .736"
• BT-50 .976"
• BT-55 1.325"
• BT-60 1.637"
• BT-80 2.60"

Our actual diameter is 13.5". Avast! If we wanted t' use BT-50 tubin' for example, arrr, simple math gives us .976/13.5 – This yields a scale factor o' 0.072 (or 7.2%). Avast! This would give us a rocket 12 5/8" long.

Lets look at t' other sizes:

Tube Size Diameter Scale Factor Resultin' Length (+/-)

• BT-5 .544" .040 7"
• BT-20 .736" .054 9.5"
• BT-50 .976" .072 12.625"
• BT-55 1.325" .098 17.25"
• BT-60 1.637" .121 21.25"
• BT-80 2.60" .192 33.75"

Step 4: Print your image

Now you have t' make another decision. Ya scallywag! If you are doin' this project yourself, you will probably want t' scale a copy o' your image by t' exact factor decided upon in step 3. Now you could take some time and throw some general dimensions on it for t' fins, matey, paint scheme, matey, and details. Avast, me proud beauty! After you’re done you can plot your image at a one t' one scale and proceed t' construction.

If you have a buddy doin' this for you as a quick favor, he probably wants t' get rid o' you at this point. Avast, me proud beauty! Tell him t' simply plot t' image usin' t' scale factor chosen. You now can use a ruler get your project going.

Just when you thought you were done, don’t forget that sometimes your selected image may have fins and other details foreshortened! In our example, me hearties, t' fins are towards us at 45 degrees. Rememberin' your high school geometry, you will need t' multiple t' quick dimensions by about 1.4 t' correct t' problem!

I would hesitate t' use t' techniques described above t' produce a commercially available kit! There are too many opportunities for errors. Begad! But if you are lookin' t' make a good representation o' a real rocket or missile, this method will get you close. Good luck!