Scale 101

[sandman]

So...you want to build a scratch scale model rocket?

You've built an Estes Black Brant II, a Mercury Redstone...maybe even a Saturn V so now you think you're ready.

Go out and buy Peter Always' Rockets of the World. I recomend the spiral bound edition so you can leave the page open on the work bench.

Also get Peter Always' "Scale Bash" if for nothing else reference. Both books are great for scale "shopping" when you're looking for that "special" model to build.

Once you decide on a model, you have to start scratching your head some more.

What will you fly it on? 18mm, 24mm, a cluster?

How big are you going to make it?

Does the rocket have stages or transition of different sizes?

What scale are you going to use?
Actually THAT is an easy one. Start by deturmining what size the "main" body is going to be.

Here is how you do that. Go to the Ninfinger site and download the Estes/Centuri body tube sizes.

Down load the chart and make a few copies to keep around. I keep at least one at my workbench and one at my computer.

Also go to Totally tubular and download his catalog. He has some "in-between" and plus sizes that you may need.

Get a pretty good calculator...at least a $5 one!

Now in Peter's book You will see a symbol next to the body that I can't reproduce here. it's a "O" with a "/" through it. This is the actual diameter of the model.

Example: a Little Joe II main body is 154" in diameter.

Now deturmine what size body tube you want to use. For the Little Joe II I used a BT-101 which is 3.938" in diameter.

Now divide the main body tube size 3.938/154= 0.0255714

0.0255714 or easier 0.026 is your scale factor. Refer back to Peter's book and find another prototype real worls dimension...let's saythe diameter of the escape motor which is 26".

multiply that 26" x the scale factor 0.0256 you get (26x0.026=) .676" or .68" this is the diameter of the models escape motor 0.68".

What I am trying to explain is the fact that you are not building it to a 1/24th or a 1/48th or a 1/50th scale...that is totally irrelavent.

You are scaling it to the main body tube that you want to use.

The scaling factor is very easy to use...it is just a multiplyer and it works on all dimensions! Like the fin thickness is 15.6", times .0256= 0.39936~~0.4"...easy!

Next class...material aquisition. (where to get stuff)

sandman

 

[Fore Check]

Material acquisition - now we're hitting the hot button of the topic.

 

[hokkyokusei]

Originally posted by sandman
Now in Peter's book You will see a symbol next to the body that I can't reproduce here. it's a "O" with a "/" through it. This is the actual diameter of the model.

Here's the symbol sandman is describing: Ø

 

[powderburner]

Originally posted by hokkyokusei
Here's the symbol sandman is describing: Ø

show off

 

[Micromeister]

Great Lead in sandman!
Fore Check: Material acquisition is a great topic. it as with most other items in Scale modeling must go back to the planning stage. If your doing a standard or even LRM scale for competition the darn 1500grams Lift-off limit must always be in the back of your mind. Your overall weight limit will likely dictate to a degree what materials will be useful on your project.
It is usually a good thing to Closely inspect all the detail photos and/or full size vehicles manufacturer's detail drawing you can get your hands on before deciding the extent of detail to be attempted on the Scale you are contemplating.
A good rule of thumb concerning detail, You smallest Detail must be larger than your Largest blemish or mistake.
I'm sure it's a no brainer that the larger the overall Scale of the model the easier the fine detailing will be. While true, larger scales can also be a curse in never allowing enough detail without going over the contest weigh limits or creating endless challanges varifing the detail on your prototype. This could include things like internal staging mechanisms, recovery hardware and systems, Payloads of any. and other non-visible structures necessary for a scale flight. Some of the FIA Scale models have machined aluminum hardware (all non structural parts) that can easily add big time to the LOwt.
Once you know these limits, you can begin to gather materials and Techniques necessary to build and detail the model.

 

[flying_silverad]

Great thread sandman. I would add the BMS catalog as well for a good source of items and sizes. There are some items in the catalog that are not listed on the site.
BMS .pdf catalog

 

[flying_silverad]

Go out and buy Peter Always' Rockets of the World. I recomend the spiral bound edition so you can leave the page open on the work bench.

I only see the regular bound edtion on the website. Am I missing something?

 

[hokkyokusei]

Originally posted by powderburner
show off

...and there's me thinking I was helping!

For those that are interested, I used the iso8859-1 entity name to specify the character. You type these in as &name; where 'name' is the description of the character you want. In this case Oslash.

You can also use the numeric code: &#number; but for me the entity names are more memorable.

There's a list of them here:
https://www.ramsch.org/martin/uni/fmi-hp/iso8859-1.html

 

[Stymye]

I have a hardcover also , still works fine,I know some earlier versions were spiral .I'm sure Peter can clarify things
In my opinion,for scale builders, it's the bible
"Spaceship handbook" is annother great read and source
I'm looking forward to the second edition of that as well !

thanks for starting the topic Sand !

 

[Micromeister]

Yes: Everyone who want's to build scale models should have at least one copy of ROTW and the suppliments. But they are ONLY a starting point. While it is possible to use a single page from ROTW for sport scale documentation it is not by any means ALL the info out there on just about any of the prototypes listed. Peter will tell you this himself. There are thousands of Scale documents out here and a lot of them either ADD to the information in ROTW or point out errors or varients not shown. There are tons of books on missile systems, "Janes" manuals, and histiorical books like "Rockets & Missiles of world war III" by Gunston that are crammed with good accurate info and more important those illusive Color photos we all would like to include in our data packets.
Rockets of the World is a Great place to START your prototype data research, not the end.

It is also a real trip to set up permission to go to a site to physically measure a prototype. Especially if it's the last remaining example of the vehicle or a well known varient, like the Iris w/out booster at Goddard space flight center, the last know Farside in the Richmond Va. Museum of Science, or the recently restored Navaho at the Cape in fla. Got some really niffty "durning renovation pics of the Navaho Sometimes the museum or collector will help with access & equipment for taking measurements to protect both you and the artifact. They may also offer other data & documents they have on the vehicle. Even if you're only allowed to photograph the real thing, it helps with fine details you might overlook in a book picture or drawing.

 

[sandman]

OK, now that you finally decided on a scale project you have to start looking for "stuff".

My wife sews so I accompany her into various sewing stores like Joanne's Fabrics and I browse looking for rocket supplies and special parts.

I do bring my cheap plastic calipers and a calculator with me on these "shopping trips".

Example; I was looking for the ring on the Apollo capsule just below the escape motor nozzles. The actual size of the prototype ring is 25.5". I multiplied that out by the scale factor (.0256) and got .65".

Looking around the store I came upon the knitting section and saw plastic rings". I have no idea what they are used for in knitting…but I don't care. They were 19mm in diameter…hmmm…too big…19mm is about 0.75"…

Looking deeper into the rack…I see 16mm rings…a quick conversion and I get 0.63" is 16mm (well, close enough!), Viola!

This is just an example…I found the exact part I needed just by keeping my eyes and options, open. I was also surprised to find 1/16" basswood in the craft section on clearance for $0.25 a sheet! How serendipitous!

My point is, keep your eyes and your mind open for locations to find "scale" parts. Other locations include auto parts stores and my favorite…Dollar stores!

For the basics tubes your best source is Totally Tubular.
https://www.buyrockets.com/buyrockets/tt.html

Check out his plus sizes(+) and the Centuri sizes for getting that perfect dimension. My Saturn 1B model uses the Centuri 2.04" tube for the main body, the Estes size BT-5 for the tanks and a 29mm motor tube for the service module.

For the fins and surface detail, spend a lot of time (with a caliper and calculator) hanging out at the Plastuct display at a hobby shop. Make sure you check different hobby shops...they don't all carry the samer stuff!

Online stores are a whole other source but it's very hard to check the actual sizes.

Here are some more places to check:

https://www.balsausa.com/wood/?shopperid=

https://www.plastruct.com/Home.html

https://www.midwestproducts.com/

https://www.balsamachining.com/

I left out a bunch I'm sure so if you guys want to add to the list go ahead.

Next "chapter" Documentation.

sandman

 

[BlueNinja]

I may be missing it on his website, but how much is it? I may need to do a little scale modeling.

 

[sandman]

Blue,

Missing what on who's website?

sandman

 

[BlueNinja]

ROTW on Peter's website. I finally found it though.

 

[sandman]

Gotcha!

sandman

 

[flying_silverad]

I placed my order via e-mail tonight at Saturn Press and will call the CC # in tomorrow. Now I have to find a small book case!

 

[Micromeister]

Originally posted by flying_silverad

Now I have to find a small book case!

[/B]

It won't help Flying: I built what I thought would be more book case than I'd ever need, 6 x 8 5 levels... It's CRAMED, overflowing, books everywhere. but worth every penny

Scale modeling Hint/Tip:
Spend some time in the Used Book stores... millitary history and flight sections...Sometimes they'll have a Space Section but not often. Amazing what you can find. Example hardback copy of G. Harry Stines book "Sounding Rockets" WOW! loads of obscure books with TONS of Scale data and those needed photos. Don't be afraid of the "Antique Book stores" but be careful on the prices.

 

[sandman]

Man, have i let this one get old...sorry gents.

Let me do some research so i get the names and emails and web addresses right and I'll get back on this!

Sorry!

 

[astronboy]

And... do not be dismayed if you need decals. Just email me, I may be able to help.

I will be introducing some new scale decals this week. No, they are not goony, but they are a kit-bash!!

Phred