High Altitude rocket using G12ST

[patbunn]

I am thinking about trying aG12st on a very light minimum diameter rocket. I will need a tracker and an altimeter for recovery.

I have done some Sims and a 29mm motor tube is probably what I will use for the body tube. Have to launch on a pretty calm day. The initial thrush kick on the motor should help.

Some sims got to 8000 feet with Gs in the 4-5 range.

 

[cwbullet]

The issue is always the recovery.

 

[heada]

https://www.radiotracking.com/transmitters
Not cheap but if you want it back, these trackers should work. They're used for tracking hawks, falcons, etc. from 10+ miles away. Small and light weight.

 

[SolarYellow]

https://www.radiotracking.com/transmitters
Not cheap but if you want it back, these trackers should work. They're used for tracking hawks, falcons, etc. from 10+ miles away. Small and light weight.

Add the receiver, that's crazy talk. Much better options from site supporting vendors that are designed specifically for rockets.

 

[Neutronium95]

I'd suggest checking out this thread. It's about building the current H record rocket, which used a H13. An optimized rocket for the G12 would look very similar.

 

[ThirstyBarbarian]

A G125 in a light rocket should teleport of the pad quickly. Push the button. POW! It’s gone. If that’s the kind of flight you like, it should do nicely.

If you are trying for maximum altitude, then a longer burn and lower thrust probably makes more sense, because less energy is lost to fighting drag at very high speeds.

Also, this won’t be an issue if you are already certified L1. But even though this post is in the mid power forum, that motor is a high-power motor that requires a certification, due to having greater than 80 N average thrust. It might not matter, but thought I should mention it.

EDIT: Oops! I guess I totally misread that! A G12 makes a lot more sense to me. Thanks for the correction.

 

[bad_idea]

He's talking about the G12, not the G125. It's a plugged end-burning SuperThunder motor like the G8 and the H13.

I have a couple of G8 motors set aside for something similar. Trouble with the G8 is that - like the G12, I believe - it is only available with a thrust ring, unlike the H13 which can be had without. The thrust ring is about 32.2mm OD, considerably wider than heavy 29mm "BT52H" motor tubing (30.7mm / 1.21" OD). Edit to add: or the 29.9mm OD of Apogee's lightweight 29mm tubes, for that matter.

Rather than live with the drag of a step at the thrust ring, I'm thinking I may just give up some frontal area and go with a BT-55 tube (33.66mm OD). Something I discovered awhile back is that BT52H is a match for the ID of BT-55 coupling.

(Off-topic, but a useful thing to know for people working with Quest tubing is that BT55 itself is a slip fit inside Quest 35mm tubing, making it a breeze to fit a 29mm motor into that size Quest tube.)

 

[patbunn]

Yep. It is a G12. Long burning . Low thrust. I have a very small
Egg Timer transmitter with GPS and an` Egg Timer simple altimeter.
The motor is plugged so I need the altimeter to deploy. I may use a streamer.
With very ,ow thrust, I am. Thinking this may look like an Estes kit. Speed is fairly slow and Gs are low .

 

[Neutronium95]

I have a couple of G8 motors set aside for something similar. Trouble with the G8 is that - like the G12, I believe - it is only available with a thrust ring, unlike the H13 which can be had without. The thrust ring is about 32.2mm OD, considerably wider than heavy 29mm "BT52H" motor tubing (30.7mm / 1.21" OD). Edit to add: or the 29.9mm OD of Apogee's lightweight 29mm tubes, for that matter.

It might be worth contacting Aerotech and seeing if sanding the thrust ring down to match the body tube diameter would be allowed.

 

[Hobie1dog]

Go Pat, you can make it happen. Make sure the launch rod is pointed away from those GD trees on the LH side

 

[bad_idea]

Yep. It is a G12. Long burning . Low thrust. I have a very small
Egg Timer transmitter with GPS and an` Egg Timer simple altimeter.
The motor is plugged so I need the altimeter to deploy. I may use a streamer.
With very ,ow thrust, I am. Thinking this may look like an Estes kit. Speed is fairly slow and Gs are low .

G12 is low thrust but has enough initial thrust to get a very light electronic-deploy rocket with a tracker off a long rail at a safe speed if built like an Estes as you say.

The G8 not so, which is why I'm looking at it as an upper stage motor. I am planning a streamer and an Estes like build for the sustainer.

It might be worth contacting Aerotech and seeing if sanding the thrust ring down to match the body tube diameter would be allowed.

I've wondered about that. Edit: Asked tfish in the Aerotech thread where he'd just replied about non-certified delays.

 

[GrouchoDuke]

Telemetrum would be nice to fly in a G12-powered rocket.

 

[Neutronium95]

Telemetrum would be nice to fly in a G12-powered rocket.

I'm actually planning on getting my HAM license so that I can get a Telemini for a H13 flight.

 

[GrouchoDuke]

I'm actually planning on getting my HAM license so that I can get a Telemini for a H13 flight.

Great!

 

[James Duffy]

Taras Tataryn did a high-altitude, long-burn, minimum-diameter F flight a couple of weeks ago using a Pyxis GPS locator device.

http://starlink-flitetech.com/pyxis.php
I was so impressed that I purchased a system for myself. Haven't had an opportunity to use it yet, though.

 

[rharshberger]

Taras Tataryn did a high-altitude, long-burn, minimum-diameter F flight a couple of weeks ago using a Pyxis GPS locator device.

http://starlink-flitetech.com/pyxis.php
I was so impressed that I purchased a system for myself. Haven't had an opportunity to use it yet, though.

That website seems to suck, and what was the cost? They also only show two dimensions for the transmitter 28mm x 5.5mm x (?) it would be nice to know how wide the unit is.

Edit: was finally able to get the documentation, the transmitter is 16mm wide.

 

[James Duffy]

That website seems to suck

Indeed.

and what was the cost?

$400 shipped for the complete system.

 

[cls]

I used BT55 for my 32mm G12 long rocket. motor retention was friction, 3M tan masking tape. it had a custom baro 1 shot altimeter for recovery. no tracker, didn't need it. loong crinkly mylar streamer, clear calm desert day. 4500 feet, about as I expected. I don't see getting 8000 feet out of a G12.

 

[Neutronium95]

I used BT55 for my 32mm G12 long rocket. motor retention was friction, 3M tan masking tape. it had a custom baro 1 shot altimeter for recovery. no tracker, didn't need it. loong crinkly mylar streamer, clear calm desert day. 4500 feet, about as I expected. I don't see getting 8000 feet out of a G12.

This is the new G12, that's a 29mm Super Thunder motor, not the old 32mm glider motor. It has significantly more impulse (144 Ns vs 87 Ns) and less frontal area. People have cleared 15,000 feet on the similar H13. I would not be surprised if the G12 eventually put the G record above 10k feet.

 

[cls]

This is the new G12, that's a 29mm Super Thunder motor, not the old 32mm glider motor.

ahhh... thanks. makes better sense now. (hoisted by our poor motor nomenclature, again...)

 

[Neutronium95]

ahhh... thanks. makes better sense now. (hoisted by our poor motor nomenclature, again...)

The nomenclature could definitely use some work. Aerotech, Cesaroni, and Loki all make a G80. Aerotech has a H123, while Cesaroni has two H123 Skidmarks. It would be nice if manufacturers could avoid using existing designations.

 

[smstachwick]

ahhh... thanks. makes better sense now. (hoisted by our poor motor nomenclature, again...)

The 32mm glider motor was designated G12-RCT, with the T for Blue Thunder as usual.

 

[Buckeye]

Mass will be the factor for this model. The tracker, altimeter, batteries, and electronic stuff will add up in a hurry.

I had a similar goal for the H13. I used a LOC Mini Magnum as the platform. Probably not the best choice, because the airframe is heavy duty, and the nose cone is ridiculously heavy. Even with 10' of Maker Beam rail for micro buttons, it barely got off the pad with enough oomph.

 

[rharshberger]

The nomenclature could definitely use some work. Aerotech, Cesaroni, and Loki all make a G80. Aerotech has a H123, while Cesaroni has two H123 Skidmarks. It would be nice if manufacturers could avoid using existing designations.

The CTI Skids are named differently...we choose only to use the H123 part

29mm 4g is 176H123-14A Skidmark
38mm 2g is 232H123-14A Skidmark

CTI's motor nomenclature is a better system IMO as it provides more information (Total Ns and average impulse) and with a simple bit of arithmatic I can know the approximate burn time.

AT just uses average thrust, if I want to know Total Ns and burn time I have to look at a thrust curve or cert document which thankfully they include on the reload packaging.

 

[bad_idea]

Taras Tataryn did a high-altitude, long-burn, minimum-diameter F flight a couple of weeks ago using a Pyxis GPS locator device.

http://starlink-flitetech.com/pyxis.php
I was so impressed that I purchased a system for myself. Haven't had an opportunity to use it yet, though.

3g is amazingly light.

 

[SolarYellow]

I have a couple of G8 motors set aside for something similar. Trouble with the G8 is that - like the G12, I believe - it is only available with a thrust ring, unlike the H13 which can be had without. The thrust ring is about 32.2mm OD, considerably wider than heavy 29mm "BT52H" motor tubing (30.7mm / 1.21" OD). Edit to add: or the 29.9mm OD of Apogee's lightweight 29mm tubes, for that matter.

Rather than live with the drag of a step at the thrust ring, I'm thinking I may just give up some frontal area and go with a BT-55 tube (33.66mm OD). Something I discovered awhile back is that BT52H is a match for the ID of BT-55 coupling.

Consider the greater surface area of the BT-55 the whole length of the rocket. I think you'd be much better off sticking with a 29mm MD tube (Apogee for this purpose) and having a slight 5-7 degree outward taper at the very back to get out to the thrust ring diameter. (If AT says its not cool to turn it down.) It might even be worthwhile to make a transition to step up in diameter with the part ahead of the engine being a 24mm tube, reducing total surface area further. Would take some sim work and validation testing.

 

[bad_idea]

Consider the greater surface area of the BT-55 the whole length of the rocket. I think you'd be much better off sticking with a 29mm MD tube (Apogee for this purpose) and having a slight 5-7 degree outward taper at the very back to get out to the thrust ring diameter. (If AT says its not cool to turn it down.) It might even be worthwhile to make a transition to step up in diameter with the part ahead of the engine being a 24mm tube, reducing total surface area further. Would take some sim work and validation testing.

That's occurred to me, but I'm not gunning for a record*, and a single diameter sustainer simplifies my life. I'm just looking to fly (or attempt) a few high flights once I get some staging experience in a larger airframe and before moving to L1.

* The G8 would be severely constrained in booster impulse for a G total impulse record, and an L0 flyer couldn't hold a record in H total impulse for long vs. an L1+ flyer who isn't limited in total propellant mass or max thrust.

 

[GrouchoDuke]

I would not be surprised if the G12 eventually put the G record above 10k feet.

Psst....the G record is above 10,000 ft.

 

[Neutronium95]

Psst....the G record is above 10,000 ft.

My memory must be failing me at the ripe old age of 27. Some of my friends have pretty convincing sims over 11k, but it remains to be seen just how high it can go I guess.

 

[GrouchoDuke]

My memory must be failing me at the ripe old age of 27. Some of my friends have pretty convincing sims over 11k, but it remains to be seen just how high it can go I guess.

Well, the 10k thing was only a year ago. 24mm vs 29mm and M1.5 vs subsonic are interesting tradeoffs. I really want a 100% crazy-long burn I motor in 38mm. Well, J, K, L, M, N & O too, in their respective smallest diameters.