13 August, 2015

TARC Update

It is well past time for an update on my TARC projects and general rocket related activities. 

I will start by saying that Southern Thunder was not kind to me or my rockets.

A test flight of the PMR-TARC15-EMS vehicle was conducted on 20 June, 2015 at the Southern Thunder Launch in Manchester,TN.  The result was a total loss of the vehicle due to failure of the upper gas block.
Before Flight
After "Flight"
The objective of this test was to verify stability of the vehicle and to gather data to estimate the Drag Coefficient of the vehicle.  Simulations of the vehicle in Rocksim indicated that a stable flight was likely and that a delay of 5 seconds would deploy the recovery system at apogee.  The selected motor was an Aerotech E18-7 with the delay adjusted according to Aerotechs instructions to be approximately 5 seconds.
Launch conditions were less than ideal with strong gusting winds.  The Launch rod was angled into the wind to aid in recovery and was not adjustable. The rocket achieved a stable flight, but there was significant weather cocking due to the high winds, this in combination with the launch angle resulted in a very low apogee altitude. The rocket impacted the ground without the recovery system being deployed.  Post flight inspection on the range suggests that the ejection gases may have been blocked from entering the recovery chamber, as indicated by a lack of soot, but given the design of the baffle system it is possible that no soot would have been present at that location had things worked as intended.  An additional potential failure mode would be operator error in adjustment of the delay.
After returning from the range it was determined that the ejection gases over pressured the space directly above the motor and blew out the Gas block at the top of the motor mount tube. 
This pressurized the area around the air-brake linkage assemblies and vented through the holes under the air-brakes.  The end result was the total loss of the vehicle and significant delay of the program.
In the future a full ground test of the recovery deployment system will be conducted and all components investigated for damage.
The PMR-TARC14-002 had a  parachute separate at deployment which resulted int he parachute being lost and a fin breaking on contact with the ground.  The damage is repairable but at this point I am canceling the program and redirecting resources to Geezer TARC Coming up in  just over a week.

26 December, 2014


As I mentioned in my TARC projects intro this rocket is already complete and has flown "successfully".  I am only missing two components for it to meet the competition requirements, an approved altimeter and the foam to protect the eggs.  As far as the technical  work that remains to be done, i need a reasonable estimate of the drag coefficient so that I can start to develop a model to determine how much ballast I will need to add to hit the target altitude.  I am also going to try to see if I can predict the variability of the motor based on some parameter that I can measure out in the field.
Since I am already well over a year behind schedule for this project and am running concurrently with my 2015 project the following table is quite an aggressive flight schedule based on the fact that I will probably have a whining, but cute, 4 year old dividing my attention from every thing that I am trying to accomplish. All in all I am very excited to get this project going again
TARC 2014 Planned Flight Schedule
Flight # Configuration Motor Objective Date
1 No Egg/No Alt E18 Stability Check 7/5/2014
2 No Egg E18 Estimate Cd 3/2015
3 No Egg E18 Estimate Cd 3/2015
4 Full F39 Full System Test 5/2015
5 Full F39 Qualification 1 5/2015
6 Full F39 Qualification 2 6/2015
7 Full F39 Qualification 3 6/2015
8 Full F39 Competition 1 7/2015
9 Full F39 Competition 2 7/2015

25 December, 2014


I know that it has been awhile since I posted anything here but honestly that is mostly because I have not had much going on with my rockets other than a few launches and lots of repairs and lamenting that they are incredibly difficult to store.  That has changed over the last 18 or so months after I rediscovered TARC.

The Team America Rocketry Challenge (TARC) asks students in grades 7-12  to build and fly a rocket to a specific set of requirements that changes every year.  The competition is designed to test the students ability to preform all of  the major tasks of a large scale project.  Then the participants are scored based on achieved altitude and flight duration with the winners being selected to compete for some fairly significant prizes.  So I decided to try my hand, unofficially of course, at the TARC as a new and interesting challenge and to focus my hobby a bit more than just collecting more rockets.  Plus I figure that with my education and experience with model rockets I should be able to be competitive with the top teams.

Currently I am working on two TARC projects one for the 2014 competition which has now concluded and one for the 2015 competition that Is just getting underway.  My plan is to document my projects here as they progresses. 


Length: 28 in
Diameter: 2.2 in
Dry Mass: 242.6 g
Payload: Two raw jumbo eggs 123 g
Motor Mount: 24mm
Motor: F39-6
Target altitude: 825 ft
Target flight time: 48-50 s
Electronics: The rules require a Perfectflite PNUT but I will initially be using an Estes altimeter.
Recovery: 2x  20" nylon "custom" parachute.

Some interesting features on this rocket include the fins, which I made out of plywood for strength with balsa inserts to save on weight. This will be my first use of a F impulse motor, as well as personal use of electronics.  To-date it has flown only once, which was mostly a success.  Only one chute deployed and there was no payload.  It was mostly a flight to check the stability, but I enjoyed it and nothing broke so, success.  I have lots more testing planned and am waiting on funds and launch dates to move forward, which likely won't be until spring. 


Length: 31.5 in (26.5 req)
Diameter: 2.6 in
Dry Mass: 521.3 g
Payload: One raw large egg 60 g
Motor Mount: 24mm
Motor: F39-6
Target altitude: 800 ft, 775 ft
Target flight time: 46-48 s, 45 -47 s
Electronics:  Perfectflite PNUT, Pro Micro from Sparkfun electronics, HS-55 sub-micro servo.
Recovery: Payload and booster recover separately  probably on  20" nylon "custom" parachutes.

This is by far a more ambitious project.  My approach for the 2014 rocket and indeed the approach most people use for this type of competition is to chose a motor that will get the rocket close to but above the target altitude and then add mass to adjust the final altitude.  This presents a unique challenge for the 2015 competition because when the top teams do their second flight at the finals the target altitude changes from 800ft to 775ft.  Just add weight and your good, but to be successful they will have to do more practice flights.  
So what is my plan?  I am going to scale down the Energy Management System (EMS) that the USU Chimaera Rocket team used in 2009 to win the NASA USLI competition.  The Perfectflite PNUT altimeter is capable of streaming telemetry, current altitude, to some other device.  I plan to feed that data into a micro controller and have it actuate a servo that will deploy air brakes at the base of the rocket.  While the use of the micro controller probably violates the rules i think that it will add an interesting challenge for me and if it works I won't have to add any mass to the rocket and have a perfect flight every time. 

Christmas has allowed me to start collecting parts and I hope to have this one ready to fly in time for Southern Thunder in late June. Time will tell however if this is just a pipe dream.

09 July, 2011

Spring In Rocket City USA

It is a well known fact that spring in the high mountain valleys of Utah comes later than most other places. It is also well known that in mid to late June that a very unique kind of garden begins to bloom in a certain garage at a certain address in Midway. Alas it has been several years since the garden bloomed there but I have recently discovered a very similar garden beginning to bud in a certain garage at a certain address in Huntsville, AL. In fact it is probably fairly likely that one could find this type of garden in almost any garage at any address almost anytime of the year. Yes I am talking about the rocket garden. The typical rocket garden life cycle goes from kit/parts to assemble rocket to various stages a painting to the final finished product ready to leap free from the bonds of the earth.... ish. My current crop includes a few classic varieties that are well known along with three never before seen varieties.
Some of the classic varieties include Orbital Transport, Comanche III, SuperNova, Gemini DC, The Alien Invader and the very nearly impossible to lose Mighty Moe. The never before seen varieties include the Feather Weight, Star Fighter and an as of yet un-named rocket that we will refer to for now as Leftovers 1.

Feather Weight (pictured on Right)
Length: 5.5"
Diameter: 0.736"
Altitude: 760'
Skill Level 1 and a halfish

After I built my Estes SolarFlare kit I decided that I would like to try my hand at a ring tail design and this little guy was the result. The Idea is a motor with fins and a nose cone that will be light enough to tumble to the ground instead of having a parachute or streamer. Will it work? We will See.

Star Fighter (Front)
Length: 20.75"
Diameter 1.18"
Altitude 880'
Skill Level 3 or 4

To be honest I am not sure where I came up with this one, but I like the end result. I guess it is part jet fighter part x-wing part "ooh, this would look cool" all mashed into one rocket. The hardest part of constructing this was filling in the gap between the body tube and the cockpit. But I imagine the paint around the tube fins will be a bugger.

Leftovers 1 (pictured on left)
Length: 7.5"
Diameter 0.736
Altitude 600'
Skill Level 2

This as its temporary name implies is made from leftovers of other projects. From the time I sat down with the leftover parts to the rocket in finished ready to paint form was less than 4 man hours most of which was from 2 am to 5 am when the baby woke me up and I couldn't Sleep.

14 September, 2010

If this isn't an Addiction I don't know what is.

So I got to thinking about it the other day and decided that I needed to do an inventory of my rockets. I discovered to my surprise that I have over 50 of them, yes, I said 50. While I am sure that this is not a world record by any means it is more than I expected. I didn't really believe just how many rockets I have because they are spread out all over the apartment so I decided to try to put them all in the same place and this is the result.

If this isn't an addiction I don't know what is.

12 July, 2010

A flash of inspiration

Length: 21"
Diameter: 1.64"
Altitude: 1500'
Skill Level 3 maybe a high 2

And it came to pass that as I was working on my other rockets this past week a vision was opened unto me. And I beheld a Rocket, and the rocket was about one cubit in length. And I beheld that it had thre fins upon three tubes that rested within the bossem of the rocket.

And I beheld that I had the components for such a rocket. Therefore, I did open the program Rocksim and did create a new file. And I beheld the file that it did bring exceedingly great joy to me. Therfore I began to lay out the rocket and to cut the centering rings and to trace the fin templates onto balsa. And the workmanship was exceedingly fine for it was mine, or in other words it was good enough for who it was for. Wherefore it did enter into my heart to finish building this rocket that it may one day ascend to heaven and there deploy its parachute and descend slowly again unto the earth from whence it was taken and to then rise again and again and bring joy to all who behold it. And again I say unto you that if your faithful unto the hobby of model rocketry that this rocket will bring you joy and rejoicing all the days of your life. And thus it is. Amen.

I hope that wasn't to blasphemous.

11 July, 2010


So this past Wednesday I got a package from the wonderful people at Balsa Machining Service (BSM) which contained everything I needed to build Two rockets that I have been looking forward to building for some time now. The first is the Classic Orbital Transport.

I have wanted one for along time. Orbital Transport is probably the rocket that got me interested in rockets in the first place. I used to spend hours down in the crawl space playing with my dads model and just imagining it fly. Then I found the instructions and decals for it on line so I bought the stuff my dad needed to fix his, (I was not the one that broke it in case you were wondering) printed a new sheet of decals and finally got to see it fly. Then I found out that BSM sold the fins for it laser cut and everything so I decided I would build my own. I bought the fins well over a year ago when I got the parts to build The Dart and have been waiting for the next time I ordered to get the nose cones and other things which I needed. It just didn't make much sense to pay $6.00 shipping for $2.00 Nose cones. Anyway the result is below, ready for sanding sealer and paint. The above picture is of my jig to keep the fins straight while the glue dried. I knew those old text books would come in handy.

My second project is the rear ejection design mentioned in my last post. It was a good build that I wish I had taken more pictures of because certain aspects of it would be difficult to just explain.

The first step wast to cut the tubes to length and mark them and then cut out the slits for the ejection gases. Once that was done I realized that there would be a lot more to building this rocket than I had originally anticipated. The most significant challenges was how to mount the shock cord and then there was no room for recovery wadding. So I could make the rocket go up but the landing part wouldn't be pretty.

So here is my solution put a screw eye in the forward bulkhead attach the shock cord to that and then stick a BT-5 body tube around it until it is into the recovery payload tube. The above picture shows how I used a spent 13mm motor to attach the body tube. By the way if you like to design and build your own rockets I recommend keeping your spent motor casings and investing in a miter box and razor saw. They make great centering rings and tube couplers and thrust blocks and are a lot cheaper, but I digress. I then had to figure out a way to get the thing into position without gluing the shock cord to the side of the body tube. This involved another BT-5. The recovery wadding problem I solved by using a baffle made out of stainless steel kitchen scrubby pad stuff. Again I wish I had taken a picture.

Keeping the fins on the rocket and straight has always been a challenge. Again the text books came in handy. As a random side not I used my Statics &Dynamics, Space systems elements, Propulsion, Mechanics of Flight and Numerical methods books. To mark the tube I drew the angles on a pizza box and cut out a hole for the body tube.

And here is the final product. Ready for sanding sealer and paint. All in all it was a good build and I am excited to finish and fly it.