My first major scratch-build - English Electric Thunderbird SAM

[BigMacDaddy]

Around 4 months ago I tried out my first major scratch-build using 3D printed parts and body tubes. I decided to see if I could do an English Electric Thunderbird SAM. I was so happy when it launched and flew stable into the sky. Accomplishing this model really changed my [nascent] passion in model rocketry -- I shifted from mainly buying / assembling kits to mainly spending time scratch building rockets (and buying body tubes, basswood sheets, other "raw" build materials, and filament). When I first got into the hobby I was surprised at how cheap kits are, but now I am even more surprised at how cheap you can scratch build rockets with 3D printed parts once you buy bulk body tubes, basswood, etc...

 

[OverTheTop]

Nice! There is one of these at the Point Cook Airforce Base near Melbourne. I have always thought it would make a great model.

 

[Funkworks]

I have one of these in the closet. Looks like fun!
https://www.fliskits.com/WPRESS/product/thunderbird/

 

[BigMacDaddy]

I have one of these in the closet. Looks like fun!
https://www.fliskits.com/WPRESS/product/thunderbird/

I not totally sure how the FlisKits version compares to my 3D printed version... I think this is the FlisKits version... I guess ratio of center sustainer tube to booster tubes is larger on Fliskits version. I actually anchored my sizes on the BT20 for the boosters (I had a bunch of cheap Viking kits) and decided to go with BT55 since it was only 4.5% smaller than it should be while the BT60 was 20% larger than it should be.

 

[lakeroadster]

Now... stuff some motors in those side pods..

 

[BigMacDaddy]

Now... stuff some motors in those side pods..

HAHA... I guess I need to start doing electronic ignition for sustainers since so many models have non-linear booster-sustainer setups... I think I could fit mini engines in those boosters and still have a bit of the look of the Thunderbird with those outward facing shrouds.

 

[Raptor 2]

Yours is a real beauty compared to the Fliskit version. Outstanding.

 

[BigMacDaddy]

Yours is a real beauty compared to the Fliskit version. Outstanding.

Thanks very much -- Looking at the Fliskit version I am thinking I should make a BT60 center tube option. I think I partly went with the BT55 to help it launch on a C-engine...

 

[BABAR]

This is your “first major scratch-build using 3D printed parts and body tubes”?
you don’t exactly start simple!

looking great! Hope it flies as well as looks!

 

[BABAR]

I’m curious about the off kilter booster cones, with the point at the lateral (relative to main tube) edge. I hypothesize the reason was that when these were burned out and released, the asymmetry of air flow “peeledl them away from the main rocket. Anybody have any inside knowledge or better guesses?

 

[BigMacDaddy]

This is your “first major scratch-build using 3D printed parts and body tubes”?
you don’t exactly start simple!

looking great! Hope it flies as well as looks!

Thanks -- It is funny because with 3D printed design it is more about specific issues related to print orientation (I do not have a resin/SLA printer so need to rely on FDM) as well as types of parts that can be readily printed vs. those that can be readily replaced with tubes or balsa/basswood/cardstock pieces. I actually started by looking at the Bloodhound but decided that the angle on the boosters as well as the other external ramjets would be too heavy. I have since designed more complex models that use more 3D printed parts so would probably be able to do this model today (might need D or E engine). The Thunderbird was [surprisingly] a pretty easy design since it relies on two main brackets to connect the 5 tubes and these can be printed flat on the print surface.



It did fly very well... Sadly I was alone (usually I draft my wife to do videos) so did not get a good video.



I have launched it a couple of times since then but one issue is that I have had a couple of hard landings -- chute has been tangled / charred / poorly packed -- and those booster mounted wings are pretty fragile. The 3D printed rear bracket gives it some good support but they flex enough to damage booster tubes / paint job. At this launch there was some confusion if the countdown was for launch or for a picture so we did not get a good video either - but a cool pic.