Overbuilding is underwhelming

Over on rocketrycenter.com, a thread introducing Binder Design’s very cool looking new Terrordactyl has veered off into a discussion on the relative merits of various materials and construction techniques. One user professed lack of interest because the Terrordactyl uses a cardboard tube and plywood fins, and said user builds only with fiberglass.

This despite the fact that, as Binder Design owner Mike Fisher writes,

Kits have flown on up to and including L motors with no glass reinforcement of the airframe although we recommend K maximum unless glassed.

The fiberglass person said,

I’ve seen other beutiful [sic] rockets built from these materials fly on L motors and they performed great, but over time they wear out easier. The cardboard can get warped or dented, and the ends can fray, and it’s really sad to see on a very nicely built rocket.

If you would consider kitting one up in fiberglass I would consider buying and building it. But until I move out of my parents house, my collection can’t grow any larger :/

and I was amused by Robert DeHate’s rejoinder,

Ahh, and there in lies the quandary doesn’t it.
A fiberglass rocket is almost guaranteed to last 10 years.
Your [sic] out of room so can’t build another rocket for 10 years Sad
And who doesn’t retire a rocket way before then anyway.
That’s where cardboard rockets shine, you build it, fly it and you can enjoy building a new one to replace it because it might have frayed ends or dents.
With fiberglass rockets your [sic] stuck with it for 10 years and how can you justify to the significant other buying a new kit when the others are perfectly flyable??
Why you can buy 2 or 3 kits for the cost of one fiberglass kit.
So it’s really all in personal preference.
If you hate building and just want to fly then fiberglass is perfect.
If you like to build and fly then perhaps a non fiberglass kit is the way to go. You can show it to the significant other and say, “Look how sad this rocket is.”.
To that they will say, “Yes, that looks so sad. You should go buy a new rocket.”
Or something like that.

But more seriously, Mike said,

Robert has some good points, although I do happen to have some Binder Design rockets built in the early 90’s in perfect shape. They will last a long time if you don’t screw up.

One of my pet peeves is people who build L1 and L2 rockets to survive ballistic impacts. That’s not really the point to being a good rocketeer. If you screw up, you pay the price and buy a new one. Being able to pull it out of the ground and reload it should not be a goal but I hear people brag about doing it all the time.

Build your rockets light while planning for all normal flight forces and you’ll fly faster, higher and be a better rocketeer.


And, Mike says,

It lowers your cost per flight. All things being equal, you can fly as high on a J as an all fiberglass rocket on a K. Be advised that an all fiberglass Terrordactyl will be triple the weight and the G-10 fins will be more susceptible to fin flutter than aircraft ply fins.


Look, I will admit to not being the lightest builder on the face of the planet. And I’ll admit I’m hilariously overbuilding the Scion, with big milled fiber reinforced epoxy external and internal fin fillets, and so forth — for a rocket that’ll probably never see anything above a G80 motor. (Why? Good question. I yielded to the impulse to do it that way.) But in the future I’d like to build lighter versus heavier, generally. Spending less money on rockets, and less on motors, to fly higher and faster; why would you not? Sure, an all fiberglass rocket built like a tank will last longer, but given the higher cost of the rocket and of the motors to fly it, how much are you really saving?

Besides, there’s just nothing elegant about overbuilding. Anyone can make a heavy, bombproof rocket, but building a featherweight bird of the same size that’ll stand up to normal flying and outperform the boat anchor — or a rocket just as heavy but twice as large — shows real skill.


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