what's a scratch build?

I know what it means, but what do you consider scratch? obviously putting a kit together is not, and making your own tubing, nosecone, and fins is. But where is the line drawn? for example, my L2 rocket was a rocketry warehouse DYOK, (design your own kit). I picked out a nose, chose the tube length, and cut and beveled the fins out of a sheet of G10. it's my design, it kicked butt, but I don't really consider it a scratch. or is it? here it is https://www.rocketryforum.com/showthread.php?121796-3-quot-fiberglass-build-need-some-fin-help/page2

I think an original design built from commercial parts can fairly be called a "scratch" build. I'd draw the line at anything not kitted and sold by some commercial entity. Your L2 rocket looks fantastic; nice job. And the "supermodel" picture in post #38 is priceless.

I agree with samb. It's not any different than baking from scratch, unless you grow your own wheat and then make your own flour. You get your ingredients from the store, then let your creative juices flow. I have several scratch builds from stuff I have acquired. Most of my tubes are oddball size so I have to make my own centering rings. The only thing I haven't done yet is make my own nose cones, and I'm getting ready to do that. I find a way to make stock NC's work with the tubes I have.

I agree with everyone else that anything not bought as a kit is a scratch build of some degree. You'll see people here that fabricate everything from lesser materials, but in the end I don't manufacture the plywood I make fins, CRs and bulkheads out of. Nor do I make the fiberglass cloth, formulate the epoxy, etc. I really like the previously used cooking analogy, everything can just be looked at as a matter of degrees, and the degrees don't matter...only that it flies safely.

Agreed, in my mind it's a scratch. If a "purist" said no it's not a scratch unless you roll your own, then it is just as reasonable to challenge them and say did you make your own glue, wire, etc. ...reasonably how far would someone take it.

With a kit, some rocketry vendor is basically telling you that these parts will go together and fly safely on a recommended set of motors. If you dream it up yourself, and you are the one responsible for determining its stability, safety, flight profile, motor choice, etc., I think it is a scratch build.

Based on my criteria above, is a kit bash a scratch build? Good question....

Bat-mite said:

With a kit, some rocketry vendor is basically telling you that these parts will go together and fly safely on a recommended set of motors. If you dream it up yourself, and you are the one responsible for determining its stability, safety, flight profile, motor choice, etc., I think it is a scratch build.

Based on my criteria above, is a kit bash a scratch build? Good question....

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I look at it as having two ways of being "scratch", specifically the design and the manufacture. If you designed the rocket then sourced the components to fit your design, it's a scratch build. If you "borrowed" the design but fabricated the components, it's scratch. If you assembled a kit... it's not scratch.

I have a Leviathan where I cut the body tube and added an av bay to make it dual deploy. I don't consider it a scratch build because the main design and the majority of the manufacture were the kit, even though I laid up the fiberglass cloth to make my glass av bay coupler, sled and av bay lids.

And this is a scratch build, Build Thread... as well as its OFFl conclusion

I like to differentiate scratch building and original designs.

For instance, you can scratch build an upscale or a clone of a kit, or from someone else's set of plans. While you have some influence and control of unseen details, the outside shape of the rocket is predetermined.

If the rocket is your own design that you build from scratch. that is another level of scratch building, in my opinion.

This same discussion occurs regularly in the RC aircraft hobby.

I like the term kit bash for the middle ground of building your own design or even light modifications from commercial kits.

On my recent certification form I had to choose between kit and scratch, no middle ground. I err on the side of scratch, not so much because I want to take credit for or pride in the design, but because strictly speaking there is no kit for what I built. I chose the fins and nose, and there are no recommended motors. I am wholly responsible if the flight was unstable or came apart at speed.

I think it's a bit of a gray area. Considering the amount of original work and design that needs to go into most "kit" builds, the only real difference mNy times is a kit comes with precut fins.

That aside, I'd call a DYOk scratch. You're calling all the shots, just getting it all from one vendor.

RKeller said:

what do you consider scratch?

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I don't know, but I have been ITCHING to build one!

Sorry, it just had to be done.

GlenP said:

I don't know, but I have been ITCHING to build one!

Sorry, it just had to be done.

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Ok... Scratch that one off the list.

cloning an oop Estes from a current kit - kitbash, cloning a current kit using different parts(alpha 3 with balsa fins) scratch, cloning a current kit using the same parts-why bother. think it is safe to say that most upscales fall into the scratch category, my 3" patriot could fall into the kit bash slot...if I had actually used a leviathan kit for the parts(even then you would still have to cut new fins), since I didn't I call it a scratch build.
Rex

GlenP said:

I don't know, but I have been ITCHING to build one!

Sorry, it just had to be done.

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that's a good one!

After seeing this post I now know who you are! It was nice meeting you at Fillible's Folly last month.

K'Tesh said:

And this is a scratch build, Build Thread... as well as its OFFl conclusion

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If it does not come with instructions and you pick the parts it is a scratch build.

RocketFeller said:

After seeing this post I now know who you are! It was nice meeting you at Fillible's Folly last month.

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Took me a second, but I figured out who you are too... Chester Cheetah. Your avatar was my clue.

Nice meeting you too.

Pointy Side Up!
Jim