National Association of Rocketry

Electronic Rocketeer—What's Happening in Rocketry

Message from the NAR President

Fellow NAR Member,

As wildfire season is upon us in a lot of the US, please be mindful of burn bans, hazardous conditions for wildfires, and do not launch when it is not safe to do so. Also, remember to have all firefighting equipment in good working condition and available.

I am just returning from the World Space Modeling Championships that were held in Zrenjanin Serbia this past week. I had the honor of being the US Team Manager and am proud of our Team. We had 13 total medals – 9 Junior and 4 Senior. Of note, Chloe He, our youngest member won a gold medal in streamer duration, and the Junior Team Coach Robin Houston won a silver medal in the same event.

S1A (altitude) Senior:
Emma Kristal Female Bronze

S3A (parachute) Junior:
Kelsey Ellison Female Bronze 

S6A (streamer) Junior:

Team Gold Medals to Chloe He, Michael Wen, Carl Schurke, Henry Dai, Camille Harris

Chloe He Individual Gold
Chloe He Female Gold
Camille Harris Female Bronze

 
S6A (streamer) Senior:
Robin Houston Female Silver

S8D (RC rocket glider) Junior:

Team Silver Medals went to Henry Dai, Bella Dai, Davud Akcin, Ryan Stenberg
Henry Dai Individual Silver
Bella Dai Female Bronze

 

Team Manager medals went to:

Steve Kristal S6A Junior

Brandon Ren S8D Junior

 

Most of our medals were awarded to first-time competitors on the world stage. The success of our team, particularly the junior team, is due in large part to the coaching by Robin Houston and Steve Kristal and the dedication of the members who spent much time over the past year bonding as a team and practicing their events. Congratulations to the entire US Team and our Supporters.

A reminder to our members, we no longer send out paper notices in the mail about upcoming membership renewals. Please make sure we are not blocked by spam filters in your email system.

I am heading to Black Rock for over a week of flying rockets for the ARLISS Project and will get in a few flights just for fun. ARLISS is a great project where student teams design payloads to achieve goals like rovers and other harsh environment tasks. The NAR is a supporter of ARLISS and we provide launch vehicles for the projects. Under the supervision of Becky Green, a former NAR board member, about 30-40 dedicated volunteers spend a week at Black Rock providing support to this endeavor. While Black Rock is a challenging environment with often harsh conditions, I have found this to be a great group to work with and look forward to traveling there each year.

Until next month, be safe, have fun and pay it forward.

John N. Hochheimer

NAR President

NAR 74537 L3

🚀 National Sport Launch East—2025
With a Side of Turkey & GRITS!

Southern Area Rocketry (SoAR), NAR Section 571, proudly invites you to NSL 2025 East with a side of Turkey & GRITS! Traditionally held as a regional launch, Turkey & GRITS has become a staple event for SoAR each year—so when the opportunity to host NSL 2025 East came up, combining the two was a natural fit!

This exciting launch will be held under NAR rules and is open to all certified flyers. Tripoli (TRA) certifications are welcome; however, all TRA members must fly under NAR guidelines (no research motors). Please contact your certifying organization for insurance-related questions.

Flight Info:

• Altitude waiver: 17,999' MSL

• Flight ceiling: 15,000'

• Recovery area: 1 square mile of cleared terrain, with 4 total square miles including wooded zones

 

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Check Out the Website and Register Today!

National Sport Launch East—2025

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Model Rocket Parachute Sizing 

I was recently leafing through a Model Rocketry magazine from June 1970. A nomograph in the article “Simplified Parachute Duration Analysis” indicated that one ounce of weight for every 44 square inches of parachute area was a “NAR minimum”. In my 50+ years as a NAR member I was never aware of any NAR mandated parachute size versus weight requirement.  A little research showed, in the Handbook of Model Rocketry, Seventh Edition, that this formula was a basic rule of thumb. Since rocket design programs often calculate and report the rocket descent rate, I took a stab at calculating what this rule of thumb means as a target rocket descent rate.

 

For a steady state descent the weight of the rocket will equal the drag force provided by the parachute. The drag force equation is F = W = C_D x A x .5 x r x V² where F is the drag force created by the parachute, W is the weight of the rocket (0.625 pounds force in this case), C_D is the drag coefficient (assumed to be 1.0 in this case), A is the reference area (in this case the parachute area or 44 square inches), “r” is the air density (0.00238 slugs/ft³ at sea level and 59 degrees F), and V is the velocity in feet/second. I will leave it to the reader to rearrange the equation to solve for V but the answer is 13.0 feet per second or about 9 miles per hour.

 

Thirteen feet per second is a ballpark number with several variables affecting the actual rocket descent rate. Local air temperature and altitude affect the air density; hot temperatures and high altitudes reduce the air density and increase descent rates. A parachute C_D of 1.0 is very conservative but was the value used in the original Model Rocketry article. As an example, Fruity Chutes states a C_D of 1.5 to 1.6 for their semi-ellipsoid parachutes. The higher the C_D, the slower your rocket’s descent.

 

In summary, there is no current “NAR minimum” for parachute sizing. The one ounce per 44 square inches of parachute area remains as a good rule of thumb.  As a Range Saety Officer, the generally acceptable final descent rate for model rockets is 15 feet per second or less. The term “final descent rate” is used because larger model rockets may utilize chute releases or two stage recovery to minimize the rocket’s descent footprint. Faster final descents present a safety risk to personnel if the rocket should land in occupied areas. Model rockets are generally built with lighter materials and without certain ruggedness features, e.g. through the wall fins, and are more susceptible to landing damage at higher descent rates.

 

Steve Lubliner

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