Paper Saturn V Scratch-build

While I rediscovered my rocketry hobby from elementary school last year, I also had a dozen 1/2A motors and nothing till fly them on, so I decided to try and convert a static paper model into a flying model. The idea was not to spend any money on the model.

After some browsing, I decided on the most overly ambitious and iconic model I could. A Saturn V. Here are the plans I started with. . I will try and find the link to the plans later.

After a couple of days, this is the final product. . Im using scotch tape fins to stabalize. The top section blows off for recovery. This model was a bit odd a rush job and barely paced the 5' test. I will test to see if it flies tomorrow and of it does, I plan to builds a second model with a lot more TLC.

Considering that this is my first scratch build and third paper model, I'm quite pleased with the project.

All that in two days? I am anxious to see what you can do if you take your time!
Straight Trails

Can't wait to hear the progress!

Got in two flights today. Quick Summary. It flies and it is horribly unflyable. I got in two flights on estes 1/2A3-4Ts and the rocket went unstable both times. I would judge the max altitude to be around 50ft. On my second flights the rocket had landed just as the ejection charge deployed. Given that the rocket has an 11g lift-off mass, it survived both flights perfectly. Could never fly this in dry weather.
I suspect that the main culprit for the instability is that the launch-lug is to tight restricting lift-off speed heavily. I roled it out of cellophane tape, and it is a bit to light. I plan on using a straw to test this hypothesis next. If it isn't the launch lug, I suspect that the culprit is weakness of the scotch-tape fins I'm using. I will calculate the stability margin of the rocket if the launch-lug fails to make a difference, but I would guess that it should be stable.

Any weight in the nose? I don't know how much you you know about rocketry, but you need to have the CP (center of pressure) behind the CG (center of gravity). Also important is the speed off of the launch rod. Are the fins large enough to keep the rocket stable in flight once it clears the launch rod? If this is a scale model, I doubt it. You may need to create a removable fin unit to help keep things stable.

I added fins made out of folded over scotch-tape. They are fairly fin and not very sturdy, so I think there is a chance that they don't provide enough drag to pull the CP back far enough. I eyeballed the fin size based on rockets I've built over the past year, but those have been significantly bigger and had plastic nose cones to pull the CG up.

I will run the CP calculation if I can't get a stable flight after fixing the launch-lug.

Sharpe said:

I added fins made out of folded over scotch-tape. They are fairly fin and not very sturdy, so I think there is a chance that they don't provide enough drag to pull the CP back far enough. I eyeballed the fin size based on rockets I've built over the past year, but those have been significantly bigger and had plastic nose cones to pull the CG up.

I will run the CP calculation if I can't get a stable flight after fixing the launch-lug.

Click to expand...

IIRC, on a Saturn V the CG has to be at the front end of the S-II stage for it to fly stably with scale size fins... Add noseweight to move the CG forward, or larger fins to the aft end.

A folded over pair of layers of tape isn't going to make fins stiff enough to stand up to flight forces... MAYBE multiple layers of packing tape, but that stuff isn't very stiff-- it's made to be flexible. You CAN get sheets of lexan or acetate or other types of clear material from Hobby Lobby or your local hobby shop in most cases, or order them online... probably 0.040 thick material would be thick enough, at a minimum...

You can either use added noseweight to bring the CG forward, or added fin area (with fins stiff enough to actually correct the flight direction of the rocket), or a combination of the two...

Good luck! OL JR