Looking for guidance

[synch2112]

Hello all, I'm Jim and I am a 58 year old who built more rockets (kits to be fair) from Estes and Centauri (may have misspelled that one) when I was a kid, and I am now a teacher. I do a rocket unit with my students at the end of the year that puts math and science together. We use hypsometers to estimate the rockets altitude. I know hysometers are old school, but I want the math component in the lesson. I am considering getting into higher powered rockets as a hobby, and I don't want to screw it up. I saw an ad for the Estes Doorknob, and it looked like a good entry point. I am looking for guidance on how to recover said rockets, and what sort of progression through the levels of flight some have taken. I would love to be able to launch a higher-powered rocket when I have my kids launch theirs. I use Estes Generic EX with either B or C engines depending on wind conditions for the day. I've got a nice-sized athletic field to launch from with a small town surrounding it. Is there a good GPS locator that I can use with a phone app (Android) to locate a rocket? I know I'm probably already getting too specific, but I am curious, and I have to think that many have already gone through something like this since rockets shouldn't be a one use type of item. I am a couple years from retirement, and I would love to do rocketry in my olfd age!

 

[smstachwick]

There are a number of electronic payloads available, (maybe take a look at Eggtimer’s systems), but you’re probably better off limiting your rocket’s altitude by increasing weight or drag. Short 4-inch diameter rockets can be very suitable for flights with G motors to under 1000 ft and can then be used to certify for L1 on an H motor. The larger rockets in AeroTech’s Enerjet line might be suitable, along with similarly-sized rockets from LOC/Precision (the LOC IV, for example), Apogee (the Zephyr), or Madcow.

To get there though, I think a Doorknob or similar Estes Pro Series II kit is an excellent starting point, since it has lighter construction and is designed to run on black powder motors. Give it a go on an Estes E16 to test it out. If all goes well, use the airframe to practice HPR building and flying techniques. Layering your fins with paper, working with epoxy, flying reloadable motors, or adding a payload bay are all techniques that such rockets are suitable for practicing.

My progression through this path was an Estes Star Orbiter followed by an Enerjet Astrobee D (in-progress). That Star Orbiter is an altitude demon so I think your Doorknob will be more suitable. Keep it low and slow and you’ll be OK.

 

[synch2112]

Thanks so much! We'll see how much response I get from my post. Low and slow is not something in my normal make up, but I will try to not over do. I was reading on a couple of other forums that hardwood fins might be a good thing for the Doorknob. Do the balsa fins disintegrate with higher-powered engines? And if hardwood is better, what types do you use, and where do you get it?

 

[smstachwick]

Thanks so much! We'll see how much response I get from my post. Low and slow is not something in my normal make up, but I will try to not over do. I was reading on a couple of other forums that hardwood fins might be a good thing for the Doorknob. Do the balsa fins disintegrate with higher-powered engines? And if hardwood is better, what types do you use, and where do you get it?

Some guys use 1/8-inch birch ply, it’s easier to get large chunks of this that are sufficiently durable, but it’s heavier. Flight stress won’t be a problem with BP motors but large sheets of balsa are more prone to damage from storage, transport, or touchdown.

Maybe check your local hobby store or see if anybody has any for sale in the forum’s classified section. There might also be third-party fin upgrades that are precut, maybe Vander-Burn might have one for the Doorknob. I don’t think you’ll have luck with this at a hardware store, the construction sheet plywood you see there is very different.

Others might have different answers. The newcomers forum gets a good amount of traffic.

 

[synch2112]

Thank you so much for your insight. I appreciate the help!

 

[Hobie1dog]

Balsa is such a delicate flimsy material to use especially for the fins, and I do build low power rockets using it only because cheap Estes kits give you no options, but other Rockets I usually stick with 1/8 inch thick plywood which you can buy at Walmart in a pack of 4 or 5 boards that are 3 inches by 7 in for five bucks. it's so much stronger, words cannot express how much stronger

 

[David Schwantz]

A lot of guys paper the fins. I have never but if you do a search there are a lot of posts on how to. I will second the plywood options. There is also G 10, which is fiberglass, but it is heavier. Many Gps unit are out there. People use ones that track hawks, dogs, they just have to be small enough to fit. I use the Eggtimers stuff and Rocket Hunters, but they are now closed for good

 

[tsmith1315]

I am considering getting into higher powered rockets as a hobby, and I don't want to screw it up

You don't need to overthink it. High power and complicated are often assumed to go hand in hand, but it doesn't have to be the case. A high power rocket doesn't have to be much more than an Estes-type build from heavier materials. The difference being higher altitudes are attainable, and you want to be more sure the recovery system (i.e., attachment and materials) are up to the task. Plenty of simple kits that take the worry out of it for you.

I'll 3rd opting for plywood fins on the Doorknob, if using HPR motors or if durability is a priority.

And I'll second the plug for LOC-Precision kits. They're a great value and your skills from building Estes kits will be transferred. I've seen them built during a launch, with 5 minute epoxy, and sent.

Low and slow is not something in my normal make up

Opinions vary there. It's not written that certification flights have to be low and slow. Low and fast is a perfectly viable option on a small field. As is high and fast, just keep it on the field.

Welcome to the forum and post some pics!

 

[synch2112]

Thank you all for your responses! Wow, you've already given me a good bit to digest, but if I pop for a larger system, I will definitely look for more durable fins for the beast. I am curious if there is a good on-line calculator to determine how big a field needs to be for certain levels of flight. Of course, as I type that, I am thinking I could simply search that out. Thank you for the specific names of recovery/rockets/build possibilities to begin this trip. Any other help will definitely be appreciated!

 

[cls]

I saw an ad for the Estes Doorknob, and it looked like a good entry point.

hi, Estes Doorknob is a really great kit, excellent value for the $$. My GF built one, using yellow glue, all stock. The fins are plenty strong, don't worry about that. One of the best things about the kit is the precision laser cut parts go together perfectly, and the interlocking fins and MMT rings make it super strong. Flies well on E through G motors. She left out the motor block so maybe an H some day?

The orange and whitescheme is easy to mask out and paint. The alternate blue scheme is more interesting, but looks like more work to mask and paint.

after you shred a few Estes Doorknobs, check out the LOC Precision HPR Doorknob kit!

 

[Old School Doug]

Thank you all for your responses! Wow, you've already given me a good bit to digest, but if I pop for a larger system, I will definitely look for more durable fins for the beast. I am curious if there is a good on-line calculator to determine how big a field needs to be for certain levels of flight. Of course, as I type that, I am thinking I could simply search that out. Thank you for the specific names of recovery/rockets/build possibilities to begin this trip. Any other help will definitely be appreciated!

Estes published the chart below as a guideline for field size as it relates to engine class. Obviously altitude, recovery device, wind conditions, etc are all variables that will come into play. I've had different rockets launched on the same F67 motor come down within several hundred feet of the pad or drift well over 1/4 mile. I personally use Open Rocket software to get pretty accurate predictions of descent rate and ground hit distance for anything I launch over a D motor (sometimes even with those).

 

[tsmith1315]

I am curious if there is a good on-line calculator to determine how big a field needs to be for certain levels of flight.

It's a two-fold question, really.

The two national clubs that support the hobby are the National Association of Rocketry (NAR) and Tripoli Rocketry Association (TRA). They have Safety codes that lay out the field size needed.

The Estes chart quoted by @Old School Doug is at the bottom of the NAR Model Rocketry Safety Code with those dimensions.

While on the subject, I'll give both clubs a big plug before mention the second answer to your question.
Either or both clubs are worthwhile to join. The NAR has programs to help with education, look here:
https://www.nar.org/educational-resources/
TRA is also involved in education, but is geared more towards high power rocketry.

Both club memberships include insurance ($3 or $5 million) for any launch carried out by a member who has landowner permission and follows the Safety Code.
NAR insurance
TRA insurance


The second answer to your question of field size was addressed above before I finished writing this reply. And that is to use a simulator to predict the flight and recovery of your rocket. OpenRocket is a free program (follow this link in this post to get it), it's very comprehensive and just went through a major overhaul with a year of thorough testing by forum members. Sims are only as accurate as the information you enter, but you can enter all dimensions and mass of your rocket, recovery system, and motors are pre-loaded:




You can enter current site weather info:



And your flight, both ascent and descent, will be predicted.
You can plots several different aspects of flight, this is the "Ground Track plot: