1/24th scale flying THOR MISSILE-prototype

[AX'E]

OK, I'm going to start something really radical, before I change my mind.
I'm Eric Truax- the one who created the scud missiles and other card rockets and scale static card models available at:

https://www.dpileggispicks.com

I’ve had a bit of a love/hate experience here on TRF over the last few years, but have made some cool friends, and gotten to know others online as well…..
I thought I’d try something new...
As the SCUD models s are now becoming a bit mainstream, it’s time to kick things up a notch or 2!
Before I lose my nerve, and change my mind, I’m posting that I'm coming out of hiding, and going semi public for a bit, here, on this forum, to do a building as I go thread on a new project:

A flying 1/24th scale model THOR variant missile.
Maybe 2 versions. One with the warhead nose, and an XSM prototype?

This is going to be a mid-power version. Quite large, and possibly very ambitious for a flying rocket made from cardstock.
Of course, I tend to think I can do anything till Mother Nature, physics, or the 'LAW' prove me otherwise.

….I laid out the basic plan for a finned final production test type in ROCK-SIM. The first real trouble I am having, is that I cannot input a WEDGE fin shape into the program. So if someone knows how to do this, it would help with preliminary data.
Of course many things I do tend to send these programs into fits, and I end up having to ‘best guess’ and flight test models till I get them right!
….especially with something the MMX Regulus flyers.
SO HERE I GO! (I think…....)

 

[powderburner]

Just to get rocsim running, can you put in the fins as flat plates? The aero-drag difference (and the flight performance impact) should not be huge and you could at least get the sim started....

 

[BobH48]

Hi Eric,

Good to see you're still around.

If you want my 2 cents, I've seen some large cardstock models fly just fine on midpower motors. I fly my Maxus 1-B on E9's all the time and I wouldn't hesitate to put something with more power in it if I thought I would get it back.

I would use 110lb. cardstock and make it double thickness. The layer of glue between the outer and inner tube adds a lot stiffness to the tube.

So, I say.... GO FOR IT!!

 

[AX'E]

HI Powder, Hi BOB!

I have the fins laid out as flat, airfoil, with the tickness of the widest part.

110lb- Yeah, I was thinking of trying single thickness, and beefing up the body with eh...what's it called, I bought at Michaels and have had stiing around for 3 years.... X-ACTO Sturdy Board?
The parts already take up a full sheet of cardstock, just for half the diameter of the body, splitup into 3 vertical sections. I guess I could overlap them at halfway points, and see what takes place... I'm concerned about weight. Cardstock is cool, but can get heavy really quick!
I tried doing that ring spacecraft EMRR had on their challenge several months back, but found it to be a 'sinking fox' for cardstock. The more i used to hold the shape, the bigger motor was needed, that I thought would have ripped it apart in flight.
....So i stopped work.

Here's another SIM I worked out....

Eric

 

[BobH48]

Originally posted by AX'E
110lb- Yeah, I was thinking of trying single thickness, and beefing up the body with eh...what's it called, I bought at Michaels and have had stiing around for 3 years.... X-ACTO Sturdy Board?

Were you planning to use a central tube and support the outer skin with rings like you did on the Scud?

If so, you could probably get away with single thickness.

Heck, I know people who use single thickness all the time without any problems so maybe I'm just overbuilding.

 

[AX'E]

Something like that, although plans are 'OPEN' which is one reason I wanted to do this thread. I was thinking of centering rings, around a cantral ube, with using vertical support pieces between rings to support the outer skin frame as well....

 

[Stymye]

this is cool and a 4" diameter cardmodel definately has my interest.

 

[teflonrocketry1]

Originally posted by AX'E
HI Powder, Hi BOB!

I have the fins laid out as flat, airfoil, with the tickness of the widest part. [Snip]
Here's another SIM I worked out....
Eric

Eric,

I think what you are doing is the best way to simulate the fins; their frontal surface area determines most of the drag.

You need to set the static margin reference in your simulation file to the maximum frontal diameter. This gives you less of a static margin 0.84 with a D12 motor and 5 ounces of nose weight. If the parachute and shock cord get pushed aft the margin could be as low as 0.55 calibers.

I also noticed the weight of the fins was way too heavy, I set these to be equivalent to two thicknesses of cardstock (0.0031" or 0.0127 ounces). If you use a BT-50 stuffer tube (instead of the BT-80) most of the way up you will eliminate quite a bit of aft end weight, giving stable flights even with the F12 motor.

Take a look at the attached RockSim file and see what you think. The only motor it might not be stable on is the G55 with a stability margin 0.59 calibers.

Bruce S. Levison, NAR #69055

 

[mike_bar]

Hi Eric,
Your getting great advice from some excellent modelers here.
Good luck.
Regards,
Mike


PS: Don't forget this is a scratch =Scale= project for all you scale modelers!

Edit: Add scale tag.

 

[AX'E]

Thanks Bruce, I'll look at the data over the next few days.
Mike is doing a beta build of a 1/96th XSM-75 version of the THOR NO.101. It a mesh of mine and Niels's work of our THOR projects.

https://www.geocities.com/nielspapermodels/

The 1/24th scale as it is right now, is strictly 'in the white' and a parts layout, with no details laid in yet. Another mesh of mine and Niels's work from our 1/96th scale static models. Lots of details to add at that scale!

Right now, my focus is on the flight engineering and construction to make it work. Making it pretty comes later!

For those interested:
I use Metasequoia LE, a freeware cad program, for the majority of my scale layout work, and Pepakura Designer to unfold the cad image into parts. I 'm using Paint Shop Pro V-7 to correct layout positions, make things pretty, and later on- add all the details.
I'm not sure what all Niels uses, we just do our own things, mesh it together, and create the versions- such is international paper modeling's gift from the internet.

....this size rocket will take awhile to add all the details for this model at this scale...!

 

[SteelyEyed]

Hey Eric,
Good to hear from you again. Hope all is well with you and yours. Interesting project. Keep the updates coming.

Best regards,
SE

PS - In case you don't remember me, I'm the guy with the full-sized SCUD missile at the office.

 

[jjnodice]

Hey Eric!

Great idea for a project, man! You'll get lots of good tips here (as you already have).

I think this is your first build-thread, isn't it? Most of the time your designs mysteriously appear on the web somewhere. It will be nice to see you work through the details and issues as they appear.

Keep us up-to-date!!!

btw, I see Rocsim files, but WHERE ARE THE PICTURES!?!?!?!?! I won't believe this is a real project until I see some paper cuts!!!

Jason

 

[AX'E]

....HA....HA.........yeah it's worth one more... HA!!!!

I'm looking at, and changing data right now;and yep! this is my first build thread...

I already have a few basic goals, but they generally involve the aesthetic appeal of the model.
One of the biggest grumbles I got about the scuds, was the seam lines. I’m going to try to eliminate those. I want to build a stalwart frame as the actual rocket, probably out of the foam board?
I would like the cardstock to simply be a wrapped skin on at least the lower 2 sections. This way I can eliminate seam lines, and also the hassle of trying to properly size the under layer to fit inside the out layer. Although it will cut down on the amount of glue used for a stronger double layer method; Hopefully it will be easier to easier and better looking to construct. That’s because I have a habit of making things available to folks over the net, so the easier the better! Not one person who has contacted me ever built that base display piece for the scud!
Maybe one day I’ll re-evaluate that…but not here, as it’s not really rocketry applicable.
The weather is supposed to be nasty most of this week, so aside from finishing a large shed I’m building; hopefully I’ll get to start putting things in order…FOR PICTURES!

 

[mike_bar]

Originally posted by AX'E
The weather is supposed to be nasty most of this week, so aside from finishing a large shed I’m building [Snip]

Is that a shed or a high power motor storage facility?

 

[AX'E]

Actually, and semi confidentially…

Bunny (my other half) and I were considering painting it like a WW-2 Bunker, and putting a large phony rotating radar dish on the top, controlled form the house... just to totally annoy and freak out the neighbors
We so bad.....

 

[AX'E]

Well, after a few off post letters and much looking at data, once again, ROCK-SIM is going to be mainly used to record what I'm doing, as I make the build. I'm going to have to put in centering rings how, and where I need them, as I need them. Cardstock is different form solid tubes, because of the areas where connecting tabs are placed to join sections together. Go. On model this large, stock paper size used determines where the breaks are, as well as the model design itself. Since this model will be made for 'LETTER' sized cardstock, and not the giant ‘A2/US C’ type paper, rings will have to go, where they go.
I’ll plot them as I go along in the Rock-Sim, and whatever additional, if any, weight it needs, will just have be added.

I decided for motors, I'm looking st ones that will 'push' the model up, rather than kick it in the ...tail. Ones that give an acceleration rate of about 70fps. seem appropriate enough.

And with that…it’s on to printing out the lower stage layout, to see how flimsy it will be, and then I'll decide where to go form there...

 

[AX'E]

Here's what I'm talking about when I say ROCK-SIM only works as a basic guide for modeling a cardstock rocket, and has yet to be correct with it‘s own calculations:
This is the 3 main parts of the lower (main) section split to fit 'letter' sized paper, and also on the naturally occurring seam lines of the actual missile.
Rock-Sim calculates 'paper' mass for this at 2.926 grams/.1032 ounces.
In the photo you can , well you can’t really see my mail scale weighing the parts at about 1.15-1.17 ounces- with 'glue tabs’ (vertical pieces) holding each section part together) 'connectors' hold the individual sections together. That’s roughly 10X’s heavier!
SUGGESTION! It might be a really good idea for a future upgrade to ROCK-SIM, or SPACE-CAD, to actually include sectional density for 110 cardstock, as most rocket folks seem to prefer that. Though 65-67lb would be nice to see too, for those of us that aren't stuck on a 'bigger, thicker, stronger is better' mentality.
ANYWAY- I'll manually be punching in the weighed component mass measurements.
UH- almost forgot, for those counting...and I imagine that's everyone? So far, it's 4 sheets of 110 cardstock, to make the parts seen, in single thickness.

 

[AX'E]

then again.. maybe there aren't enough of us weird eggs making flying toys from cardstock, this large, to bother?

 

[mike_bar]

Oh boy, build pics too. You will fit right in here Eric

I like the paper modeling not the computer modeling

I'm no RockSim expert so I will read the replies as they come in.

It looks like a fun build, good luck.

Regards,
Mike

 

[AX'E]

It occured to me that for those who aren't familiar with the THOR misile, or the early prototype test vehicles; maybe you want to see a couple of pictures?
So, here is one picture of what I'm trying to build:
The XSM-75/XPGM-17 final form missile, in test phase, that still used the fins.

 

[AX'E]

....and this one:

 

[AX'E]

ok...after much thinking, I came up with an idea, that a paper cone flush with the bottom of the rocket, fitted around a 24mm motor sized tube assembled using the dry glue/iron method; with a thick centering ring on top, pressed down and glued to force the cone out. I though this would hold the lowest part of the main body where the fins would go, rigid. I was 1/2 right...
...The cone idea seems to be working with good glue adhesion using plain old white Glue. (Elmer's in this case.)

 

[AX'E]

Using a 1/2 inch thick foam insulation material from DOW, which is really cheap and available at the major stores like Lowe's, and home Depot; held in place with a paper inner ring 'seemed' like a good idea....
....but getting the body tube not to budge out when it's only a single sheet of 110 cardstock proved a problem, as did glue adhesion

 

[AX'E]

....and, here's the view from the top.

 

[mike_bar]

Originally posted by AX'E
[Snip] I'm going to have to get radical in my approach to this, and remake a few parts.
...try try again!

Very nice design Eric. The cone should work to transfer thrust from the central (25 mm) motor tube to the outer 4-inch skin.

One small suggestion regarding strengthening the outer skin near the fin-can area: Gussets.

See the following article for contruction tips.
Regards,
Mike



Paper Centering Rings for HPR
Apogee's Model Rocketry E-Zine
Issue #63 (09/26/01)
By Tim Van Milligan

 

[AX'E]

this thread is closed for me.... I need to seriously re-think a few things. I'm not giving up, This CAN be done. I'm going to experiment, and then I'd rather show what I did that worked... THANKS FOR THE SUGESTIONS ALL!
...back into hiding