Upscale Experts.....I need some help (Orbital Transport)

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Green Jello

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There are some really cool kits out there that I'd love to do an upscale version of. Most of them are complicated and I've never attempted an upscale of any kind. The main one I was thinking of was the Estes/SEMROC Orbital Transport:

Orbital Transport-lg.jpg
https://www.semroc.com/Store/scripts/RocketKits.asp?SKU=KV-66

My main question is, how do you guys do the calculations for the sizing of all the parts? Do you just measure the originals and do the math, or is there an easier way with some software?
 
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Oh cool. Thanks. I do have Rocksim, but I have never noticed that feature.

What kind of Excel formulas do you use? Is it just the size multiplied by a percentage?
 
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New size / Old size = Scale Factor

Helps to have two known dimensions, for rockets that's normally the diameter.

Example:
Upscale a bt-50 based rocket to bt-80.
2.6 / .95 = 2.74 <-- Multiply the known lengths and diameters from the original by this to scale up.

Or go the other way for a scale model like of a Nike Smoke using a bt-50 tube:
.95 /13.5 = .07 <-- Multiply the known lengths and diameters from the original by this to scale down.

You can automate that by putting your known lengths and diameters into a spreadsheet and applying the scale factor.

kj
 
Exactly as KJohnson said;
Up or down Scale the Orbital Transport is a great choice. Remember to give your upscales enough power to fly Safely & well. Don't overlook clustering motors as an option.

148-b2_3 OT's Pic&Flt Page_01-14-04.jpg
 
I wonder if the balsa layouts from the manual .PDF are an exact layout and can be used as templates.

I don't see why not. They are usually provided so that you can use them to cut replacements if you break a fin.

kj
 
I've decided to go ahead with an Orbital Transport. I wonder if the balsa layouts from the manual .PDF are an exact layout and can be used as templates. Has anyone done this?

View attachment 118924

I've also found from other threads that Excelsior has decals in BT-60 size and Mark at Stickershock has many sizes.

https://www.excelsiorrocketry.com/product.php?id_product=139

https://stickershock23.com/ORBITAL_TRANSPORT.html


If you go to www.spacemodeling.org/JimZ/estes/K-42.pdf and look at page 14, you'll see a different template layout then the one you've posted.

I printed out page 14 with NO SCALING and used the Booster Marking Guide to check the scale of the templates.

The Booster Marking Guide wraps around a BT-50. The diameter of a BT-50 is.976 inches.

.976 inches X PI (3.14) = 3.06464 inches.
I find it's easyer to use metric for small measurements, so....
3.06464 inches X 25.4 mm (1 inch) = 77.841856 mm ( you could round up to 78 mm)

When a metric ruler is used to measure the length of the Booster Marking Guide wrap, you come up with 78 mm. How 'bout that!

It's now known that the templates are the correct scale. You can use these templates for upscaling.
 

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I think I've settled on doing a BT-60 upscale of it.....so as far as I can tell, that is 168% or 1.68x

Main body tube in the original is a BT50 (0.95" ID) So that x 1.68 is 1.595" ID (BT-60)

The glider body tube original is a BT-20 (0.710" ID) So that x 1.68 is 1.1928". What the hell tube is that?
 
I think I've settled on doing a BT-60 upscale of it.....so as far as I can tell, that is 168% or 1.68x

Main body tube in the original is a BT50 (0.95" ID) So that x 1.68 is 1.595" ID (BT-60)

The glider body tube original is a BT-20 (0.710" ID) So that x 1.68 is 1.1928". What the hell tube is that?

Use the Outside Diameters when upscaling.

1.637 (BT-60)/.976 (BT-50) = A Scaling Factor (S/F) of 1.677254

I.677254 (S/F) X .736 (BT-20) = 1.2344589 inches. A BT-55, at 1.325 inches is the closest at nearly 1/10th of an inch (2.54 mm) larger then needed.

You could cut the BT-55 length wise and shave off a couple of milli meters, then glue the tube back together. But then you'd have to modifiy the nose cone too.

Me, I'd just go with the BT-55.

Don't round off any numbers until your ready to cut something.

images.jpg
 
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Any ideas where I can get all the original tube lengths?

I'm trying to avoid buying the SEMROC kit for $30, but I may just have to.
 
Thanks, but I meant the tube lengths from the standard kit so I can upscale them. I know the body tube is:

BT-50 18.0" ---> BT-60 30.25"
 
Thanks, but I meant the tube lengths from the standard kit so I can upscale them. I know the body tube is:

BT-50 18.0" ---> BT-60 30.25"


These measurements are from the Estes Body Tube/Kit Reference v3.1 for kit #K-42/1242, Orbital Transport

BT-50 18"
BT-20D 6.5"
BT-20J 2.75"
BT-5T (4) 1.5"
 
I downloaded the OT plans from JimZ and went to a huge Kinko's store in a nearby city to enlarge the fin plans. I think the store is now FedEx. They had a huge machine and I enlarged the drawings by a factor of 4. Jason Wares did something similar. Black and white enlargement is not as expensive as color, but it will still cost something. I would recommend the Sandman for the Orbiter nosecone. I was very happy with his product and bought two.

IMG_1632.jpg
 
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I think I've settled on doing a BT-60 upscale of it.....so as far as I can tell, that is 168% or 1.68x

Main body tube in the original is a BT50 (0.95" ID) So that x 1.68 is 1.595" ID (BT-60)

The glider body tube original is a BT-20 (0.710" ID) So that x 1.68 is 1.1928". What the hell tube is that?

Here ya go... something I whipped up a couple three years ago to make it easier to see what tubes are available and the sizes... sort of an 'integrated list" of tubes that have been produced and are/were available...

Some new ones may have come around since then, and some may be hard/impossible to get... some tubes were never offered for sale except in a particular kit (not as parts) and aren't listed...

They're listed from smallest to largest size, in order, regardless of manufacturer, and contain both the inside and outside diameters...

View attachment SemrocTTTubesizechart[1].txt

Later, good luck, and hope this helps...

OL JR :)

PS. Usually, "close enough" is good enough for most upscales-- IE if the tube is off 1/10 of an inch, you won't hardly notice it... not worth the effort to "roll yer own" to get the "perfect" sized tube, unless you're doing Internats-quality scale rockets for competition, when holding dimensions to the thousandths of an inch IS important...
 
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I downloaded the OT plans from JimEZ and went to a huge Kinko's store in a nearby city to enlarge the fin plans. I think the store is now FedEx. They had a huge machine and I enlarged the drawings by a factor of 4. Jason Wares did something similar. Black and white enlargement is not as expensive as color, but it will still cost something.

View attachment 119082

That is exactly what I am planning on doing. Fortunately, my office has a graphics department and I have many printers the size of Buicks that I can use for free.

These measurements are from the Estes Body Tube/Kit Reference v3.1 for kit #K-42/1242, Orbital Transport

BT-50 18"
BT-20D 6.5"
BT-20J 2.75"
BT-5T (4) 1.5"

w00t! Perfect. I think I have it all now. Thanks so much.
 
One more question for the Orbital Transport experts....

I see how the glider is attached with the short dowel in the launch lug holder....but what causes it to release? Is is just the jolt from the ejection charge and it always works?
 
When the ejection charge and blows the nose cone out, the relative booster motion is in the opposite direction. So, the inertia of glider causes it to slide off at the pin location. I believe that the forces for the 4x OT are substantially greater than the original model, so I added 2 more short launch-like lugs on the wings to slide into pins that are on the strut fins that support the rear of the glider.
 
For those of you who have done a specifically BT-60 upscale of the OT....what thickness balsa did you use for the glider wings? Also what engines have you used on it? I'm thinking of making the engine mount take up to Estes Es in BP or I can use my 24mm AT reloads.
 
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