Flying the alphabet

Like the thread title says, this post is about flying the same rocket over a wide range of different impulse classes. If you want to chime in go ahead. I'm going to post some graphs below.

One night while fooling around with plotting software... I started to make some interesting figures. Anyway, for my fiberglass rocket kits, the x-axis is the total N-s and the y-axis is the agl altitude.

I was excited to find that many of my birds have a linear slope. Here's the DarkStar Jr, below. Notice the coefficient (~5.9) because it seems to change (decrease) with diameter and weight.

Next up are my Competitor 3" and my DarkStar Extreme. Same basic plots, but scaled in x- and y- to fit all of the data.

The last altitude plot requires further explanation. My Intimidator 4 is a kit bash. Not every flight was the same airframe per se. For example, at LDRS 38, the Additve Aerospace camera shroud melted and so increased drag and this is not comparing apples to apples with the other flights. There were other... ehm fin glassing issues in-between flights, so I need more data to nail the slope down.



Here is the 'whole family' on a single scale. Poor Gizmo XLDD on an M2080 is all alone by himself, need to call Tim and order some L's, M's, and nasty N's to figure out his slope.

It should be feasible to fly a 54mm MD solely on Loki Reds:
g66, h90, i210, j320, k627, l1040, m1378

I just like to bring this up whenever possible. :-D

The last of my plots are, well, top secret "Dad-only" information as each reload has a price $$$ to go with it. It just so happens that the cost of a reload is roughly linear with N-s. Using that information, I will leave you with 'fuel cost' and 'cost to altitude' plots.

Enjoy.

Interesting data and nice plots. So the data is not from simulations, but actual launches?

dhbarr said:

It should be feasible to fly a 54mm MD solely on Loki Reds:
g66, h90, i210, j320, k627, l1040, m1378

I just like to bring this up whenever possible. :-D

Click to expand...

Yeah that's pretty cool! I've stuck with non-MD because they seem to last longer with me... I've crashed one or two MDs.

You get the data and I'll plot a line through it

mbeels said:

Interesting data and nice plots. So the data is not from simulations, but actual launches?

Click to expand...

Thanks! I enjoyed making them.

everything was flown. Data goes back to 2015 I launch about 5-10 rockets each year.

You could add another level of analysis, and plot the slope of those plots vs rocket weight, or vs rocket diameter (probably diameter^2 I'd guess) and see if the linear trend continues. More excuses to build and fly lots more rockets

Very cool

Good information.

We had a guy at BALLS who was doing the alphabet from I to M with a single rocket.
I would let smaller than K launch if there was a good reason.
Airframe was carbon 4" with a 3" motor mount. For smaller motors was to launch without the payload section and use motor ejection. To save time a long motor mount adapter was used so the parachute could be pre packed. Just drop into airframe, spin on the aeropack retainer, attach to nose cone and go. If I remember correctly he did I, J, K and then the weather got him. He changed out the motor coming back in truck to range head and went straight to RSO for next flight.
Planning ahead is your friend.

M

mbeels said:

You could add another level of analysis, and plot the slope of those plots vs rocket weight, or vs rocket diameter (probably diameter^2 I'd guess) and see if the linear trend continues. More excuses to build and fly lots more rockets

Click to expand...

That's another good idea.

My first thought was that the linear part of the data might tell me the drag coefficient, but it is becoming clear to me, as you suggest, that the slope depends not only Cd, but also the area (diameter^2) and weight.

I've got the DarkStar (Extreme+Jr) and Competitor 3 dialed in. So, I think that a few more 'L' flights on the modified Intimidator would be good to pin down its actual slope. BTW, I've got an L1040 and L1030 that just need a sunny day and a flight card.

If I find out my two 4" birds have a similar slope, this second level of analysis would be most interesting indeed. It would suggest, perhaps, that all WM kits built in a certain style (e.g. "Extreme") scale with diameter and weight.

When I find these new correlations, I'll be sure to post them.

-Jeb

This is very cool! Thanks!

My first thought was to look at the slopes of the regression lines of each rocket: steeper slopes would indicate more efficient rockets.

But, it appears that the slope decreases with larger rockets. Which, makes sense. As mentioned above, it would be interesting to add another variable to perhaps explain this efficiency roll off - diameter, mass, time spent transonic, etc...

I run an alphabet contest at Hellfire every year. Flying three "letters" of motors on a single rocket is fairly straight forward, four is more difficult, and five is the most I've ever seen. Your plots are good at showing what a huge range there is across these impulse classes.

Back before there were reloads and altimeters...
LOC EZI built stock, smallest motor was a F110-4, largest J100-10. Many G, H, and I motors, all with motor ejection.

I flew the alphabet last launch without leaving "A".
1/4A3-3T
1/2A3-4T
A10-3T
A8-3