Mach 2 attempt

Onebadhawk
eggtimer rocketry
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teepot said:
Interesting name. I also have a Don't Blink. a 29mm MD I built for a G80-13. ThrustCurve says 6000'. It's going to have a tracker though.
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That’s really interesting because I launched this same rocket on a g80-13 twice and it was projected to 6000.
 
Hey boss, the margin for mach 2.01 is pretty small so if you really want to be sure that you broke mach 2 I would aim for at least 2.05 and most likely 2.1. If your sim weights are super accurate alongside launch conditions (temp, altitude) then your sim should be pretty spot on unless your motor underperforms by alot. The one thing you can do to hit this speed is reduce fin size or upper airframe length (or a combination of both). That should get you into the comfortable area of well into mach 2. Just make sure you do good building techniques!
 
charrington said:
Hey boss, the margin for mach 2.01 is pretty small so if you really want to be sure that you broke mach 2 I would aim for at least 2.05 and most likely 2.1. If your sim weights are super accurate alongside launch conditions (temp, altitude) then your sim should be pretty spot on unless your motor underperforms by alot. The one thing you can do to hit this speed is reduce fin size or upper airframe length (or a combination of both). That should get you into the comfortable area of well into mach 2. Just make sure you do good building techniques!
Click to expand...
Yea it really all depends on the conditions that exact day. If the humidity is low enough it will be as high as Mach 2.12 but with the projected humidity for those couple days it looks like around Mach 2.05 which is sorta hit or miss. I’m gonna be there all 3 days helping with volunteer stuff and other people with finding lost rockets and of course flying my own.
 
Joey Draney said:
Yea it really all depends on the conditions that exact day. If the humidity is low enough it will be as high as Mach 2.12 but with the projected humidity for those couple days it looks like around Mach 2.05 which is sorta hit or miss. I’m gonna be there all 3 days helping with volunteer stuff and other people with finding lost rockets and of course flying my own.
Click to expand...
Meant to switch those. Higher humidity and heat would mean faster and lower and colder would mean slower.
 
I have built several MD rockets with ttw fins. You just need a normal fin slot and glue the fins into that slot. Makes a h3ll of a difference. I like to use an old motor case with mold release on it inserted into the MMT. This keeps your fins from blocking motor insertion.
 
David Schwantz said:
I have built several MD rockets with ttw fins. You just need a normal fin slot and glue the fins into that slot. Makes a h3ll of a difference.
Click to expand...
That's how I build them too. Makes for a stronger fin attachment. You are not relying on peel-strength for fin retention.
 
Here's a project I've flown several times - the Double H-Bomb.
100515-double_h-bomb_at_da.jpg
I fly it out of a tower, mostly at Black Rock, using an H268 staging to an I200. When everything works, it goes about 11k feet.

I used fiberglass tubing throughout, thick fillets, and fiberglass on the fins - don't remember how much.
One key ingredient is a low-profile 29mm aft closure, manufactured briefly by Tom Rouse and Monster Motors. I'm trying to find more.
I use apogee ejection and tracking by Walston/Merlin tone tracker.
Exciting as hell and difficult to get right.
 
ROhmen said:
Here's a project I've flown several times - the Double H-Bomb.
View attachment 582056
I fly it out of a tower, mostly at Black Rock, using an H268 staging to an I200. When everything works, it goes about 11k feet.

I used fiberglass tubing throughout, thick fillets, and fiberglass on the fins - don't remember how much.
One key ingredient is a low-profile 29mm aft closure, manufactured briefly by Tom Rouse and Monster Motors. I'm trying to find more.
I use apogee ejection and tracking by Walston/Merlin tone tracker.
Exciting as hell and difficult to get right.
Click to expand...
Looks like an awesome build! Do you have any video of it? I’d love to see it.
 
Joey Draney said:
I can’t measure the speed with anything because it would add to much weight to put any sort of electronics in it. This is sort of just a yolo flight.
Click to expand...

Joey:


Some inputs:

1) Others can confirm, for supersonic rockets my RASAero II software is more accurate than RockSim. For a "yolo" or "bragging rights" flight, if you are not taking any in-flight data, you should run the rocket on the most accurate software, because that is the Mach number which you are going to claim for your rocket. RASAero II is free, and it can import RockSim files, but since more details on the rocket have to be inputted you'll have to spend a little time converting your rocket file.

2) I'd really encourage you to put at least a simple barometric altimeter on the rocket. Others here can recommend some units, but they are quite small and would not really decrease the performance of your rocket by much. From this you would get the apogee altitude of the rocket. Why is that useful? If your RASAero II predicted apogee altitude is very close to the barometric altimeter apogee altitude, then you can be reasonably confident that the RASAero II predicted maximum Mach number is probably very close also. Just this one piece of additional information will tell you a lot about how the flight went. Without it, you just shot a rocket off, and then exclaim "it went Mach 2!".

3) I would not use the velocity from the barometric altimeter, because it is not hooked up to a calibrated pitot (air data) system. But it will take accurate altitude data through apogee, as the rocket is flying at very low velocity through apogee. (As a note, combining an accelerometer with a barometric altimeter is a powerful combination, the accelerometer provides the best data during boost and early in the coast, the barometric altimeter provides the best data through apogee.) Many of these small barometric altimeters just record the apogee altitude, and then they beep it out when you recover the rocket via a series of beeps. Again, they are small, they will have little impact on the performance of your rocket. But you will have to get your rocket back, the data is stored on-board the rocket, not telemetered to the ground. Thus, see item 4).

4) Since you have to get the rocket back to get your flight data, depending on what kind of field you fly from (grass or a dry lakebed), for this type of small rocket you likely want to put a beeper in the rocket (others can recommend units) that lets out a shrill beeping sound to help you figure out where the rocket has landed. Your rocket will be flying high and fast, and since you have made it as small as possible to maximize performance, you are likely going to have a hard time finding the rocket.


By the way, this is very doable. For STEM classes I've thought of similar just over supersonic rockets using smaller motors using similar instrumentation.



Charles E. (Chuck) Rogers
Rogers Aeroscience
 
Chuck Rogers said:
Joey:


Some inputs:

1) Others can confirm, for supersonic rockets my RASAero II software is more accurate than RockSim. For a "yolo" or "bragging rights" flight, if you are not taking any in-flight data, you should run the rocket on the most accurate software, because that is the Mach number which you are going to claim for your rocket. RASAero II is free, and it can import RockSim files, but since more details on the rocket have to be inputted you'll have to spend a little time converting your rocket file.

2) I'd really encourage you to put at least a simple barometric altimeter on the rocket. Others here can recommend some units, but they are quite small and would not really decrease the performance of your rocket by much. From this you would get the apogee altitude of the rocket. Why is that useful? If your RASAero II predicted apogee altitude is very close to the barometric altimeter apogee altitude, then you can be reasonably confident that the RASAero II predicted maximum Mach number is probably very close also. Just this one piece of additional information will tell you a lot about how the flight went. Without it, you just shot a rocket off, and then exclaim "it went Mach 2!".

3) I would not use the velocity from the barometric altimeter, because it is not hooked up to a calibrated pitot (air data) system. But it will take accurate altitude data through apogee, as the rocket is flying at very low velocity through apogee. (As a note, combining an accelerometer with a barometric altimeter is a powerful combination, the accelerometer provides the best data during boost and early in the coast, the barometric altimeter provides the best data through apogee.) Many of these small barometric altimeters just record the apogee altitude, and then they beep it out when you recover the rocket via a series of beeps. Again, they are small, they will have little impact on the performance of your rocket. But you will have to get your rocket back, the data is stored on-board the rocket, not telemetered to the ground. Thus, see item 4).

4) Since you have to get the rocket back to get your flight data, depending on what kind of field you fly from (grass or a dry lakebed), for this type of small rocket you likely want to put a beeper in the rocket (others can recommend units) that lets out a shrill beeping sound to help you figure out where the rocket has landed. Your rocket will be flying high and fast, and since you have made it as small as possible to maximize performance, you are likely going to have a hard time finding the rocket.


By the way, this is very doable. For STEM classes I've thought of similar just over supersonic rockets using smaller motors using similar instrumentation.



Charles E. (Chuck) Rogers
Rogers Aeroscience
Click to expand...
Thanks for all the Tips! I definitely plan on implementing most of these in the future. This weekend I just hope to gain some knowledge from everyone I can and will decide whether or not it makes sense to launch it. If things are looking good and I decide to launch it I will. Bragging rights will not be included with this flight just because it’s more of a prototype that I’m testing without electronics to make sure my building methods are up to standards. Once I know that it is or isn’t I will implement those things into the next version confidently. I fully understand the risk that It is going to be extremely difficult to find a rocket so small after such a high flight and I’m accepting those risks for this flight. I have the building materials to make another one however I would love if I could get this one back. Thanks Again.
Joey
 
Meant to do an update on this thread. During the building process I had later notice one tiny bubble in the fiberglass about half way up the tube but didn't quite realize it untill putting it on the pad and didn't think much of it. The launch went really smooth until about 80 percent through the burn when I suspect it hit max q and sure enough it shredded right at that little bubble and then into another piece because of the forces on the rocket. Amazingly enough the fins held on going sideways at somewere around mach 1-1.6 and then the lower section of the rocket continued going up because the fins were still held on. It hit apogee and went in ballistic somewhere about a mile away. And somehow someone found it and took it to lost and found. Amazingly again the fins were still intact. As if things couldn't be more surprising the other 2 pieces of the rocket came to lost and found and I was able analyse what had happened. The fiberglass motor had completely snapped in half from the impact which tells you it was coming in pretty hot. Not the most successful flight but definitely not a failure. Learned a lot about building technic and I'm already working on don't blink 2.0 which should have an altimeter and possibly a radio tracker
The photos below show the damage. Upper section is what broke off above mach and all of the damage seen on the lower section was from the ballistic impact.
 

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Joey Draney said:
Meant to do an update on this thread. During the building process I had later notice one tiny bubble in the fiberglass about half way up the tube but didn't quite realize it untill putting it on the pad and didn't think much of it. The launch went really smooth until about 80 percent through the burn when I suspect it hit max q and sure enough it shredded right at that little bubble and then into another piece because of the forces on the rocket. Amazingly enough the fins held on going sideways at somewere around mach 1-1.6 and then the lower section of the rocket continued going up because the fins were still held on. It hit apogee and went in ballistic somewhere about a mile away. And somehow someone found it and took it to lost and found. Amazingly again the fins were still intact. As if things couldn't be more surprising the other 2 pieces of the rocket came to lost and found and I was able analyse what had happened. The fiberglass motor had completely snapped in half from the impact which tells you it was coming in pretty hot. Not the most successful flight but definitely not a failure. Learned a lot about building technic and I'm already working on don't blink 2.0 which should have an altimeter and possibly a radio tracker
The photos below show the damage. Upper section is what broke off above mach and all of the damage seen on the lower section was from the ballistic impact.
Click to expand...
good try..

remind us how your body tube was made? Glass (what weight # of layers?) over card ? what epoxy?

Tony
 
Hmmm. At Mach 2+ surface finish becomes critical, and those fins look pretty rough. I would definitely work on getting a very smooth, even finish, all the way around.

Of course it’s unfortunate the airframe failed, but getting it all back was a big win. It’s hard to figure out what wrong when you don’t have anything to analyze.

I agree with your sentiment that the flight was not a failure, in that you clearly learned a lot and can put those lessons to use on your next rocket.

Good luck!


Tony
 
tfish said:
good try..

remind us how your body tube was made? Glass (what weight # of layers?) over card ? what epoxy?

Tony
Click to expand...
It was two layers of 8.9 ounce glass on the fin can with west systems epoxy slow cure. And the body tube was 2 layers of 1.5 ounce glass. I might switch to just one layer of 4 ounce glass in the future
 
manixFan said:
Hmmm. At Mach 2+ surface finish becomes critical, and those fins look pretty rough. I would definitely work on getting a very smooth, even finish, all the way around.

Of course it’s unfortunate the airframe failed, but getting it all back was a big win. It’s hard to figure out what wrong when you don’t have anything to analyze.

I agree with your sentiment that the flight was not a failure, in that you clearly learned a lot and can put those lessons to use on your next rocket.

Good luck!


Tony
Click to expand...
Yes thank you I completely agree and that is another thing I am going to try and improve in the next rocket
 
Joey Draney said:
It was two layers of 8.9 ounce glass on the fin can with west systems epoxy slow cure. And the body tube was 2 layers of 1.5 ounce glass. I might switch to just one layer of 4 ounce glass in the future
Click to expand...
Like plywood..the more thin layers make fiberglass things stronger. Not that this video talks about or shows that..maybe it will be helpfull.



Each tube you make gets better..

Tony
 
tfish said:
Like plywood..the more thin layers make fiberglass things stronger. Not that this video talks about or shows that..maybe it will be helpfull.



Each tube you make gets better..

Tony
Click to expand...

Thanks Tony. I definitely have gotten better at it since. I'm currently building a 20 year old BSD 3 inch Thor and I've fiberglassed all of the tubing for that. Should have a build thread soon.
 
manixFan said:
Hmmm. At Mach 2+ surface finish becomes critical, and those fins look pretty rough. I would definitely work on getting a very smooth, even finish, all the way around.

Of course it’s unfortunate the airframe failed, but getting it all back was a big win. It’s hard to figure out what wrong when you don’t have anything to analyze.

I agree with your sentiment that the flight was not a failure, in that you clearly learned a lot and can put those lessons to use on your next rocket.

Good luck!


Tony
Click to expand...
The SR-71 guys would run a felt eraser (for those who remember such things) over the surface to detect any imperfections.
 
Buster said:
The SR-71 guys would run a felt eraser (for those who remember such things) over the surface to detect any imperfections.
Click to expand...
I wasn't born for such things unfortunately however I've heard the work they did was pretty impressive. Which makes sense it's Lockheed.
 

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