Rocket for live telemetry

Hello,


this is my first post on your forum, so hello


I'm currently building a radio telemetry module for use in a rocket - it'll transmit x/y/z g-force and barometric pressure - I'll then be able to model the flight afterwards - I'll get it to log the data on-board, too, in case the transmission fails.


What I need next, though, is a rocket to put it in. I've used very small rockets (...by the standards of this forum! I've used up to D motors...) in the past, but haven't launched anything for over ten years. I'd like to re-start with something that'll give me more height and payload than a "starter" kit, so I'm looking at either the Estes Ventris or the Estes Ascender. I'd also like to start flights using Cesaroni motors. I'm building my own launch platform based on the designs here (I'd happily buy one from them, but shipping to the UK would be very much "think of a number and add a few zeros) and I'm building a launch system based on the design here.


Obviously, this is a bit of a step-up from a starter-kit with a D motor in the back of it, so I'd very grateful for any advice. I was worried that I might be trying to start "too big", but, having read three posts here about getting rockets beyond mach 1 and over 3 miles high, I'm now a bit worried that nobody here will take me seriously!


Any advice/guidance would be very welcome - the nearest launch-site/club to me is half a days drive away, so I'm figuring this all out with only google for support


Thanks,


LTR.

Welcome to the forum, LTR.

There are a lot of "higher and faster" flyers here and they are quite vocal but there are lots of "low and slow" advocates, too. Personally, I can't be of much help to you as I've only flown a few mid-power rockets and haven't designed any of my own. I think your choice of CTI products is a good one.

If you could supply the size and weight of your payload, some folks here should be able to give you some useful advice. I know some flyers in my clubs have done live telemetry in the past and with equipment that isn't as small as you can get now.

At some point, getting with the club you mentioned would be a good idea. Maybe someone in the club lives closer to you and could give you some guidance.

I hope you get some good info here and complete your project.

Hey, welcome to the forum. I will speak from the standpoint of someone who was out of the hobby for a while and got back into it this last summer, with level 1 as my goal. I found building a few basic kits to be helpful remembering a bunch of stuff, and also working with new techniques and materials. While the premise hasn't changed a ton in 10 years, I found there are some very useful techniques being added to kits that I hadn't been exposed to yet. Finishing rockets (paint) was never my strength, so it was also nice to practice on the smaller stuff where I didn't care as much. So it might be worth your time to build one or two low power rockets, of which you can probably find some fun payloads.

I agree with Kenn that CTI is a good choice. I found them to be very simple to work with as a new high power flyer, and it took a ton of the intimidation out of reloads. Size and mass of your project would be very useful for people to give a more in-depth answer as well. It sounds cool, and hopefully you will do a post about it so others can learn from what you are doing.

The last thing I found really important was setting up and using a simulator. I use openRocket, but there is also rocksim.

Really nothing special about mid-power rockets. You will use the same basic techniques from LPR. I agree that if you've had a 10 year gap you may want to do 1 or 2 smaller ones to "get your feet wet".

I also mostly fly CTI for its simplicity and think it is a good choice

Do you have any info on the weight of your telemetry package (including the battery)?

The largest diameter of the Ventris, including nosecone is 2.5" which is not that ideal for payload. Also, if you think about the extra weight you need something to get that rocket off the pad quick, like a G80, I don't know what the CTI equivalent of that is. How big is your payload, could you possibly post dimensions here?

Hello all,

thanks very much for all your advice and thoughts.

I'm still building/testing my payload, but it's going to use the following modules:

IMU
Pressure Sensor
433MHz Transceiver
Microcontroller
LiPo

I'm estimating the all up weight to be about 85-100 grams (about 3~3.5 oz) - the dimensions are a bit of an unknown at the moment, but hopefully it'll all fit inside a cylinder 30mm in diameter, 75mm long (about 1 3/16" x 3").


I haven't tried RockSim, but I've been designing rockets in OpenRock for a few weeks - I've modelled the Ventris and got about 350m (1300') out of it on a G80 motor (CTI 29 equivalent) with my 100g payload - for fun, I tried a 2-stage setup with 2x G80 motors (a pricey launch!) and got 925m (just over 3000') out of it!

I'm still at the stage of testing my payload on the kitchen table, trying to get a reliable radio link working, but whenever I get it ready to fly, I'll post some details

Thanks for your help

Super cool project that you are working on! Welcome back to rocketry, and I look forward to following this

I hope you know how to keep the RF out of the rest of the circuitry. Looks like a fun project!

What are the dimensions and weight of your electronics?

RocketryBill said:

The largest diameter of the Ventris, including nosecone is 2.5" which is not that ideal for payload. Also, if you think about the extra weight you need something to get that rocket off the pad quick, like a G80, I don't know what the CTI equivalent of that is. How big is your payload, could you possibly post dimensions here?

Click to expand...

I always recommend a Leviathan. Thicker body tube than the Ventris, very easy to overbuild it for a L1 attempt. Easy enough to make an av bay for it too.

Barkley said:

I always recommend a Leviathan. Thicker body tube than the Ventris, very easy to overbuild it for a L1 attempt. Easy enough to make an av bay for it too.

Click to expand...

Exactly what I was thinking. They stopped making Leviathan's, but you can still buy them at supply stores like AC Supply. An even better option would be a Aerotech G-Force or Sumo, just make sure to use a high power rocket motor like a H or I.

LTR said:

Hello all,

thanks very much for all your advice and thoughts.

I'm still building/testing my payload, but it's going to use the following modules:

IMU
Pressure Sensor
433MHz Transceiver
Microcontroller
LiPo

I'm estimating the all up weight to be about 85-100 grams (about 3~3.5 oz) - the dimensions are a bit of an unknown at the moment, but hopefully it'll all fit inside a cylinder 30mm in diameter, 75mm long (about 1 3/16" x 3").


I haven't tried RockSim, but I've been designing rockets in OpenRock for a few weeks - I've modelled the Ventris and got about 350m (1300') out of it on a G80 motor (CTI 29 equivalent) with my 100g payload - for fun, I tried a 2-stage setup with 2x G80 motors (a pricey launch!) and got 925m (just over 3000') out of it!

I'm still at the stage of testing my payload on the kitchen table, trying to get a reliable radio link working, but whenever I get it ready to fly, I'll post some details

Thanks for your help

Click to expand...

Sounds like you are headed in the right direction: A) you have modelled and simmed the rocket in OR (its nearly on par with Rocksim IMO), B) As long as the dimesions are close both in size and weight a Ventris would be a fine choice, C) Staging APCP composite motors requires electronics as they don't work the same as BlackPowder (BP) motors, but as you said that was for fun idea. Make sure and check in with some of the UK rocketry clubs as they can give you specifics related to flying and the laws of your country, and better yet join one and go fly with them most rocketeers I have ever met are helpful to fellow fliers and are always willing to share advice (usually you have to ask for it though).

Welcome to TRF!

Hello all,

again, thanks all for your enthusiastic input!

I've seen the "Leviathan" on a few forums etc, but haven't yet found it for sale - if it's been discontinued, that's probably why. I'm finding that rocket availability on the UK is rather more limited than in the US... I'm starting to see that L1 certification will be something I'll need to consider, probably sooner(ish) than later(ish)...

On a project update note; I've got my radio link working and am currently transmitting+receiving relative and absolute air pressure as well as relative and absolute altitude - quite pleased to have got that far in a weekend!

There's a rocketry event "near" me later this year (give or take 200 miles...across mountain roads) which I'm planning on going to - hopefully I'll know what I'm talking about when I get there

Thanks for your advice again

A footnote to the above that I thought might amuse/shock those of you viewing this from "across the pond":

I really like the look of the Aerotech G-force, but...

US Price : 103.48USD + 0.00USD Delivery

UK Price : 290.57USD + 9.41USD Delivery

...guess I'll be sticking with Estes for the time being!

LTR said:

A footnote to the above that I thought might amuse/shock those of you viewing this from "across the pond":

I really like the look of the Aerotech G-force, but...

US Price : 103.48USD + 0.00USD Delivery

UK Price : 290.57USD + 9.41USD Delivery

...guess I'll be sticking with Estes for the time being!

Click to expand...

Ouch!

LTR said:

A footnote to the above that I thought might amuse/shock those of you viewing this from "across the pond":

I really like the look of the Aerotech G-force, but...

US Price : 103.48USD + 0.00USD Delivery

UK Price : 290.57USD + 9.41USD Delivery

...guess I'll be sticking with Estes for the time being!

Click to expand...

Damn.. and I thought 90 bucks was expensive here so I was waiting until it went back down to 60...

You could scratch build a nice 3-4" diameter rocket.

Estes Partizon.

LTR said:

Hello all,

again, thanks all for your enthusiastic input!

I've seen the "Leviathan" on a few forums etc, but haven't yet found it for sale - if it's been discontinued, that's probably why. I'm finding that rocket availability on the UK is rather more limited than in the US... I'm starting to see that L1 certification will be something I'll need to consider, probably sooner(ish) than later(ish)...

On a project update note; I've got my radio link working and am currently transmitting+receiving relative and absolute air pressure as well as relative and absolute altitude - quite pleased to have got that far in a weekend!

There's a rocketry event "near" me later this year (give or take 200 miles...across mountain roads) which I'm planning on going to - hopefully I'll know what I'm talking about when I get there

Thanks for your advice again

Click to expand...

Go on the estes website, buy a scion and a 3"x10" fin tube and an extra 3" coupler. Leviathan is yours for under 40 usd and you have an extra BT to extend it and done stage / av bay. You will need L1 motors though. Finished one today.

For a payload the size you're talking about, the Ascender, if you convert the upper red section into a payload section (put a ply bulkhead in the middle of the coupler that joins it to the white lower body instead of gluing the two together as the instructions call for) would work. Someone above mentioned the Partizon. That would work. So would the Argent. The Argent already has a payload compartment that's 2 inches in diameter and has a free length of about 9.5 inches (after taking into account the shoulders of the transition below and the nose cone above). I think it's the same nose cone as the Ascender, just molded in white vs. the Ascender's black.

And of course the Ventris as you've already determined, or making a Leviathan out of a Scion, as has also been suggested would work as well.

Actually, to just prove the concept, again with a package the size you're aiming for, just get an Estes Vagabond or QCC Explorer and convert the upper section to a payload compartment as I suggested for the Ascender. Fly it on 24mm motors (Estes D12s and E12s, CTI 24mm 1 or 2grain motors, Aerotech SU E20s or F44s). Then you can go bigger.....


Added: actually - the package you describe could (barely) fit in a BT-55-based model. I don't know if they're still available on your side of the pond (another model discontinued) but an Eliminator or Eliminator XL could have a payload section added with a coupler and a ply bulkhead as well. Quick, simple, and pretty cheap. This one is set to take 24x115mm motors (Estes black powder Es).

BTW, except for the Ascender (haven't built the one I have on hand) I've done the payload section conversions on all the others I've suggested so I know it's very straightforward. I did a similar conversion on the upper 6 inches of my Leviathan as well - I LIKE flying altimeters .

Let me be the first to recommend a fiberglass rocket with a 38mm motor mount. A 2.1 or 2.6 inch airframe would fit your payload easily. Properly built, the rocket will take literally years of abuse, and if you make it long enough you will be able to launch higher and higher for simply the cost of more propellant. For your weight class, I think this is the best route to spend more time thinking about flying and payloads and less time thinking about rockets and motors.

The one catch here is properly bonding and building with fiberglass. However, with a little care, cleaning, and sanding, it is no worse than building with cardboard and wood. I have even seen it done with Bob Smith 15m epoxy over a weekend, for a rushed L2 certification. Scrub all parts before you start, and sand any surface to be bonded, before it gets glue!

The Cesaroni 38mm motors, in particular, are so incredibly easy, that literally the biggest problem people have is spacing out completely and trying to fly the reload directly in the rocket while forgetting to use a case. Meanwhile I have dug out lawn dart recovery failures and flown them with no repairs needed. Spend a week building a rock solid rocket, then forget about it entirely and simply use it as a tool for your payloads and electronics work.

The Ventris works great for payloads like this, it's got a pretty big payload bay if you cut the bottom off the nose cone (since you don't need the shock cord loop). If you're just doing testing and you're not chasing altitude records, 29mm motors are the way to go... you can go all way from E to I impulse, and the new DMS G80's will get you plenty of altitude and acceleration for testing your electronics.

I'm with Cris (cerving) on this. The Ventris is cheap and easy to build. It was the gateway drug that got me back into this hobby. If you have built Estes-style rockets in the past, you will have no problem assembling it in a few hours, and you will have plenty of fun flying it. Its payload section is perfect for what you are trying to do: just wrap your system in bubble wrap and send it up.

Please share some of the details about your telemetry system when you have it finished. I'd love to see how something like this is built.

Hello all,

thanks for all the info! There's quite a bit to think about, now...

I'll let you know which way I end up gong...

I gather you are in the UK. AFAIK, you can't buy from the Estes Website, so do you have access to the kits? Does L1 certification apply in the UK?