1: You need rules to make it fair. Have a minimum weight. If someone in your pack has a lathe they can get their rocket a lot thinner than someone with a vegetable peeler. We say you cannot be lighter than a half of an ounce. If so they have to add weight. Also I have found your kit might weigh half as much as mine, due to wood densities and variances. So if we get our rockets the same size yours will be half the weight of mine. I open all kits and weigh each half of wood and divide into 5 weights from lightest to heaviest. Then put back together a light one with a heavy one. Ex. you have 1,2,3,4,5 weight rating for each half of wood and 1 is the lightest. So I put a 1 with a 5 until I am all out and then a 2 with a 5 or 4 until all out and then finally the middle weights are put together. At least everybody starts out around the same weight.
2: You need an auto winder. We are lucky enough to have a mechanical engineer who also works for a company where he could get parts and build us a 4 rocket winder for next to nothing. Even if you have to invest in the parts for one it is well worth it. I do have plans for one that a guy on the east coast sent me. It is pricey but maybe you can do it for less with different supplies.
3: Forget about timing the race. Go with a points for distance method. This is also good if you have a rocket leave early for some reason it does not affect the results because it is for distance and not time. Here is what we have done. We went to an 8 lane 60 ft. track. Yes I said 60 ft. Believe it or not we did have one rocket hit that last zone once and many others in the zone right before it. We had colored zones on the floor (we used the cheap colored plastic table cloths from you local party store folded and taped to the floor). Each zone had a point value and the next farthest zone was worth two more points than the previous. If you were the farthest rocket in a particular zone you got a one point bonus (this was to help break up ties).
First zone was red 20' you got 1 point + a bonus point if farthest in that zone.
Second zone was blue and 10' and you got 3 points + a bonus point if farthest in that zone.
Third zone was yellow and 10' and you got 5 points + a bonus point if farthest in that zone.
The last four zones were all 5' and went up by two points accordingly and had bonus points.
Why 8 lanes you ask? The boys just want to see their rocket race and it was quite the spectacle. Plus we made score sheets for them that were color coded so they could keep track of their score unofficially of course. The official score and racing lineup was done with an Excel spreadsheet.
4: So the following are things we have done that we feel improves the racing. I have done hours upon hours of small scale testing in my garage to get results. I have an Excel spreadsheet of my results if anyone would like to see what I have done. I am no scientist or engineer just an determined dad trying to make a better derby for the boys.
Rocket display: Here is a few pics of a rocket display/holder that I built which is good for displaying the rockets after check in for the design competition and judging. It is made out of PVC,wooden clothes pins and zip ties.
Prop Holder: Because we auto wind and also stage the rockets 24 at a time (we have 24 carriers on the line at a time so we do not have to reset after each heat. They just get moved to the end of the track.) we need something to hold the prop form unwinding. You can use an S shaped piece of wire that goes on the prop and then the rocket hanger but this can cause the hanger to break free if not glued properly and is also harder to get off. We have come up with another design because I have also replaced the dowel in the back. So now we have a straight piece of wire running the length of the rocket and then bends at a 90 degree angle and goes into an eye hook at the back. See rubber band holder below.
Rubber band Holder at the back: So how many times have you wound the rocket tried to take the dowel off the winder and it slips back into the rocket. Too many and this slows down the races. So I have eliminated the dowel. We now use a cork in the back with an eye hole on the back and a hook for the rubber band on the inside. The eye hole hooks onto the winder and when done you just take off the cork and put it into the back of the rocket. No more loosing the dowel inside.
This is just to show you the size of the corks. I got these at Hobby Lobby for testing but bought a bunch online from a brew supply company for a lot cheaper.
Rocket transporters: Seeing we prewind all the rockets and then stage them we need something to hold them all and get them back to the starting gate. I have two identical transporters that hold all the rockets in their heat order and that are on casters. We change the props and bands and then wind the rockets as they come off after their heats. So this is all done at the finish line end. We have the next round/phase order already and place them in the appropriate heat and lane on the transporter. When all rockets are wound we then just roll the full transporter to the start gate for the pit crew to start staging the rockets and we roll the empty one from the start gate to the finish line to hold the next set of rockets that will be wound.
Props: They are inconsistent. I have had previous race results where the second heaviest rocket wins a trophy and the second lightest does not. I am working on this problem as I speak the only thing we did last year was we put together all props as a pack. (This also eliminates people putting them together the wrong way.) They are not in your kit when you get it. Then we randomly change props after each heat. So you will race with four different props during the race.
I have a feeling it is the shaft and the inconsistencies with it being bent over the prop.
Rubber band: The ones in the kit I feel are too long also not really consistent in size and they knot up too much. We use a 5" rubber band but its rubber is not as sturdy and only lasts one heat. Since we are changing props we also change rubber bands each heat. Goal is to find a consistent prop and quality rubber band that we do not have to change.
Carriers: So we put small eye hooks into the top of our carriers. You can bend them open with a small screw driver to get them on the fishing line and then pinch them closed with pliers. We also use small straws/coffee stirrers (not the figure 8 ones) and cut them length wise and slide them onto the fishing line and then through the eye hooks which we slightly pinch down to hold the stirrer. The eye hooks let us quickly change a carrier if needed and also as said before hold the stirrers which are sprayed with silicone spray on the inside and slide down the track really well.
5: The Track. So here is our new set up and also the type of fishing line we use.
Anchors: The ends of the track need to be anchored because of the tension that is applied to get the fishing lines tight. We use skids at each end with 5 gallon buckets filled with sand for weight. Then cargo straps are run from the skid to the ends of the track(4 total at each end (one at the bottom three at the top, both sides and the middle) to hold them in place.
Line tension: So how to get line tension is an issue. Do you run one continuous line but then if there is a break or issue the whole track has to be restrung. We do individual lines but here is how we try to get close to the same tension. The line supports at each end have eye hooks. We hook a cargo strap crank to each eye hook at one end. Then we attach fishing scales ($5 each at Walmart) to the eye hooks at the other end. We tie the fishing line onto the scale at one end and then onto the crank at the other. Then we start cranking them down until we get the desired tension on each line. You will get close on all lines but not exact.
Type of fishing line: I did hours of small scale testing last year with four different fishing lines and found a clear winner. The four types used were. Below are the types and averages for distance in inches with a new rubber band each time wound 60 times by hand for all the testing.
Avg. for line type: 30lb. Mono 123.1041667 (Stren high impact)
50lb. Braided 114.7083333 (Stealth Braid Spiderwire)
100lb. Mono 92.70833333 (Offshore Angler tight line)
80lb. Braided 140.7083333 (Cortland Master Braid)
As you can see the 80lb. braided worked the best.
Start gate: Ours is made out of PVC and can be adjusted seeing I do not glue anything in. I sometime will use some electrical tape to hold things together.
I know I am basically reinventing the kit itself but we are having great success and the boys are have a great experience. We will reuse most of the stuff so there is a one time cost to get the corks,scales,cargo straps,carriers,carrier mods and such but after that it is maybe new bands,table cloths each year which is reasonable for a derby budget.
I hope this post helps you out with your Space Derby. I know a lot of packs are not doing it because of issues. I hope our pack maybe solving some of those for you. Feel free to use or modify any idea we have come up with. All I ask is that if you find a better / another way, just post it here and we all then can benefit from it.