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Small 29mm Rocket at 5,000 ft = lost?

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DTH Rocket

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My latest project is to build G-motor powered rockets that go supersonic, but there isn't a good way for me to find them again. I will lose a lot of money on this project if I can't find a relatively cheap, simple and reliable system to track them again. I can't very well fork out $399+ for a receiver and transmitter, are there any lower cost solutions?
 

n5wd

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My latest project is to build G-motor powered rockets that go supersonic, but there isn't a good way for me to find them again. I will lose a lot of money on this project if I can't find a relatively cheap, simple and reliable system to track them again. I can't very well fork out $399+ for a receiver and transmitter, are there any lower cost solutions?
Sure, if you already have some of the other needed components. For example, the only thing I've needed to buy to track my rocket is a Beeline transmitter. $85 for the tranmitter and charger. Of course, I already had a suitable receiver and yagi antenna that I used for other things in amateur radio before I needed to track a rocket.

Used hand-held FM receivers or transceivers can be had for anywhere from $50 to $150. Add a home-built antenna (Google "WA5VJB Cheap Yagi") and you could get set up for a little less than $400 total (including the $89 for the Bee transmitter). You do need an amateur radio license, though, before Greg will sell you the transmitter.

And, if you're handy with building your own, you can save a few bucks by building your own transmitter.

There are other tracking transmitters out there for about the same price or a little more, but most of 'em use the 219-221 MHz band and are CW mode, and you won't find a used receiver that covers that band/mode, much less one for $150. Figure $400 for that receiver, plus the antenna.
 
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Marsman

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You need a Ham Radio licence to use the beeline right? Do GPS trackers require them?

As to the original poster's question, what about optical tracking? Put some brightly colored powder near the parachute and look for the puff in the sky. However, I've never actually used this before, as my foray into supersonic 5,000 ft. projects was lost on it's first flight. I was counting on being able to see a relflective streamer in the sunlight. No chance.

My advice: build it cheap and use a single use motor. Then if you don't get it back, it's not a huge loss.
 

MarkM

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You need a Ham Radio licence to use the beeline right? Do GPS trackers require them?.
Yes, because most (like the Beeline) still use the 70cm band which requires a Ham license to operate. I'm unaware of a GPS system that can be legally operated without a Ham license.

Another possibility is to try a sounder, like a personal alarm, that is activated when the drogue chute/streamer is deployed. Most of these are relatively loud and can be heard from a good distance -both horizontal and vertical - which may allow you to identify the rocket's location during the decent by "tracking the sound." It's not perfect, by any means, but it is cheap. It may help.
 

bobkrech

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AFAIK the OOP 24 mm Vaughn Brothers Extreme and the OOP 24 mm Rocket Vision Machbuster http://www.rocketreviews.com/reviews/all/oop_imp_mach_buster.shtml launched on the OOP 24 mm AT G55 (aka Rocket Vision G55) are the only G-impulse model rocket kits that were capable of exceeding Mach 1, and that's because they were only 24 mm in diameter.

I managed to launch my Machbuster twice on a F72 simply due to chance. A soccer player found and returned it from the other end of the launch field some 3500' from the launcher. I wasn't so lucky on the second flight.

Even if you could, your apogee will exceed 5,000 feet if you break Mach, and it is unlikely that you will be able to see the rocket at apogee. You may see deployment if the chute is illuminated just right, however adding the weight of a tracker or other device may reduce the T/W enough to prevent you from reaching Mach 1.

It will be difficult to verify that you broke Mach without launching an accelerometer to determine the peak velocity because the rocket is small, and even if you generated a shock wave, it will likely be drowned out by the roar (shock waves) generated by the motor.

The maximum velocity of a rocket is ultimately restricted by the instantaneous thrust and the instantaneous drag. The drag of a minimum diameter "29 mm" rocket is 42% greater than a minimum diameter "24 mm" rocket. If both rocket weigh the same, the T/W of the larger rocket must be 42% greater than the smaller rocket to achieve the same velocity.

What motor are you planning to use? I'm pretty sure you can't do it with current production 29 mm G-impulse model rocket motors due to the drag of the 29 mm rocket body restricted to an 80 N average thrust.

Bob
 

DTH Rocket

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My advice: build it cheap and use a single use motor. Then if you don't get it back, it's not a huge loss.
True, that is what I'm planning on, but I'm testing nosecone shapes vs. Mach number and I'll need to use electronics that I don't want to lose.

What motor are you planning to use? I'm pretty sure you can't do it with current production 29 mm G-impulse model rocket motors due to the drag of the 29 mm rocket body restricted to an 80 N average thrust.

Bob
I'm using the 137 N-sec G80. I'm almost positive it'll do it, RockSim predicts Mach 1.6 max, but I have to admit that's a bit optimistic.

And I'm not expecting to hear the sonic boom.

By the way, the Apogee Aspire 29mm kit breaks mach. Also, I've heard that the LOC Aura can do it. It just takes lightweight yet robust building techniques.
 

DTH Rocket

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Another possibility is to try a sounder, like a personal alarm, that is activated when the drogue chute/streamer is deployed. Most of these are relatively loud and can be heard from a good distance -both horizontal and vertical - which may allow you to identify the rocket's location during the decent by "tracking the sound." It's not perfect, by any means, but it is cheap. It may help.
This sounds like a good idea... do you have any suggestions for personal alarms that work good with rockets?
 

Adrian A

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True, that is what I'm planning on, but I'm testing nosecone shapes vs. Mach number and I'll need to use electronics that I don't want to lose.



I'm using the 137 N-sec G80. I'm almost positive it'll do it, RockSim predicts Mach 1.6 max, but I have to admit that's a bit optimistic.

And I'm not expecting to hear the sonic boom.

By the way, the Apogee Aspire 29mm kit breaks mach. Also, I've heard that the LOC Aura can do it. It just takes lightweight yet robust building techniques.
The G80s will definitely get smallish 29mm rockets well past Mach. I did a similar project to look into the drag of different nosecone shapes. I used a Beeline transmitter and (naturally) a Parrot altimeter. Here is a plot of Cd vs. velocity based on the measured accelerations during the coast phase:



A thread about nosecone shapes, including this data, is here:

http://www.rocketryplanet.com/forums/showthread.php?t=1644
 

n5wd

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You need a Ham Radio licence to use the beeline right? Do GPS trackers require them?
Yep, the B and the B/GPS both require a ham license.

Marsman said:
As to the original poster's question, what about optical tracking? Put some brightly colored powder near the parachute and look for the puff in the sky.
If you can see a puff of tracking powder at a mile high, then your eyes are much better than mine! :shock:

Marsman said:
My advice: build it cheap and use a single use motor. Then if you don't get it back, it's not a huge loss.
Yeppers.
 
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jcsalem

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The basic Beeline is great and fits in a 29mm tube. Unless you're in a hilly area where the signal is likely to be blocked, I think the GPS version needlessly takes more time and $$$.

I've never lost a rocket equipped with a Beeline (well, except for the one where I forgot to enable the electronics -- ugh!) To save money, buy a used hand-held transceiver (I got my FT-50 used for $125 a few years ago and it's still working great). I made my own Yagi at first (which worked well) but later switched to the Arrow-brand 5 element yagi which was more rugged.

For cost, it's hard to beat the Loc8tor tracker (reviewed on TRF v1) but the range is very poor (often < 100' on the ground).

Jim
 

hardinlw

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I built several 29mm G-powered rockets. On a clear day, I could optically track them to apogee but never found one on the ground by walking to where I thought it landed. I saw one drift away on a streamer because of strong high altitude winds and one I found the next day (at Geneseo) while looking for another rocket. I used SU G80s and one G125 which both simmed to supersonic, but I never heard a sonic boom. The boom will not intersect the ground near the launch point. At Mach 1, the shock wave is a plane which will never hit the ground. As the Mach number goes up, it wraps back around the nose cone as a conical shock, so the point at which it intersects the ground will depend on Mach number and altitude. Where the boom can be heard will be a ring some distance out from the launcher and may not be very wide if the rocket does not stay supersonic long, so you may never hear it.
 

bobkrech

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The G80s will definitely get smallish 29mm rockets well past Mach. I did a similar project to look into the drag of different nosecone shapes. I used a Beeline transmitter and (naturally) a Parrot altimeter. Here is a plot of Cd vs. velocity based on the measured accelerations during the coast phase:



A thread about nosecone shapes, including this data, is here:

http://www.rocketryplanet.com/forums/showthread.php?t=1644
Nice work Adrian. You have indeed shown that if you pay attention to the details the way you did and work hard to get the Cd as low as possible that you can break Mach with the G80. Your flights however do have the advantage of starting from a base altitude in excess of 1 mile and that helps significantly since the density at one mile up is only 85% that of sea level so you automatically have 17% lower drag loses than us coastal folks. I personally don't have a simulator I trust to do the transonic drag corrections properly, so I'd be curious how your rocket would perform starting at sea level.

I'm happy to see that you have also demonstrated to the hobby community that the conic shaped nose cone is not the lowest drag high speed nosecone. The professional aerospace community has used the von Karman shape for quite a while when drag minimization is important. I motivated the Sugar Shot Nose Cone study and and the VK design nets us a full 10% greater altitude that the original conic NC would have provided.

Bob
 

Adrian A

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Nice work Adrian. You have indeed shown that if you pay attention to the details the way you did and work hard to get the Cd as low as possible that you can break Mach with the G80. Your flights however do have the advantage of starting from a base altitude in excess of 1 mile and that helps significantly since the density at one mile up is only 85% that of sea level so you automatically have 17% lower drag loses than us coastal folks. I personally don't have a simulator I trust to do the transonic drag corrections properly, so I'd be curious how your rocket would perform starting at sea level.
Thanks, Bob. Recently I've made my own Excel-based simulation so that I can plug in my measured Cd vs. velocity from my last 38mm shot to make my own predictions. It would be pretty straightforward for me to modify the inputs for a 29mm bird with the same drag characteristics and a G80 motor to see what happens for different base altitudes. I need to make some progress on my new altimeters at the moment, but maybe later I'll give that a try. Certainly it also helped to have only 18 grams for the whole av-bay, including tracker and deployment batteries.

I motivated the Sugar Shot Nose Cone study and and the VK design nets us a full 10% greater altitude that the original conic NC would have provided.

Bob
Are you sure it was a VK design? I thought I remembered the hypersonic optimal or paraboloid won the trade. Better than a cone though, in any case.
 

dave carver

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A lot of hardware stores and bike shops sell strobe flashers of some sort. If you wait until dark lost rockets are easy(generally)to find
 

bobkrech

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Are you sure it was a VK design? I thought I remembered the hypersonic optimal or paraboloid won the trade. Better than a cone though, in any case.
I went back and checked the last design and it does appear that a 5:1 fineness 3/4 power series hypersonic optimum to have been the one modeled with the lowest drag for the MiniShot vehicle (shown below) however it does not appear that the Haack series including the VK was included in the study.



I know that in the early days of SS2S I strongly opposed a 3:1 fineness Conical NC profile because is is not very good, especially around Mach, and the drag down velocity between the first burn cut-off and the second burn ignition needs to be minimized. Since the Isp of candy propellant is horrible, you can get to 100 km unless you use a single stage burn-coast-burn propulsion sequence. The original plan was to burn for 7.5 second and after reaching M~1.6 to cost through the lower atmosphere from ~10,000' or so to 25,000' or so, and then to accelerate from M~1.2 to M~5.5 from ~25,000' to ~40,000'. This implies that the absolute drag in the Mach 0.8-Mach 2.0 region must be minimized to retain as much velocity and momentum as possible and the cone is the worst shape for this region. Most aircraft use a VK or modified VK NC in the region to minimize drag in the transonic region, however the power series is pretty close and may be easier to make. The VK however has a bigger internal volume for payload IIRC.

In any case, we will be conducting drag studies in the MiniShot flight test to make sure we understand the NC drag before we move on the the 60% scale vehicles.

Bob
 

dave carver

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Another budget thing to try for sighting the rocket on the way down is to use a Chrome Mylar streamer, the reasons are obvious.
 

DaveHein

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I suggest using the BeeLine transmitter. That's what I did, and its helped me find my minimum diameter 29mm rocket a few times. The ham license isn't too hard to get, but you do have to study a bit before taking the test. There are online sample tests that you can practice on. After a few hours you should be ready for the test.

Dave
 

Handeman

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I was able to borrow a Walston transmitter on one of my flights. If you know someone that has one, that is an excellent method of getting the rocket back. Baring that, a mylar streamer that was mentioned before, with some tracking powder and a good pair of binoculars will allow you to track some pretty small rockets to some pretty good altitudes and back down.
 

Estimado

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A question regarding the Apogee Aspire. ?s it possible to use a parachute with this rocket? I have a large area to launch in. I would like to avoid using a streamer on this model, if at all possible (more for aesthetic reasons than anything else).
 

deandome

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I would like to avoid using a streamer on this model, if at all possible (more for aesthetic reasons than anything else).
Umm...how on earth does streamer recovery vs. chute affect the aesthetics of a rocket? ANY rocket?

I know it's not super cheap. but I'd think the best high-altitude, single deploy option w/out a tracker would be Wildman's new Blackhawk: http://wildmanrocketry.com/default.asp?groupid=1&groupid1=612121482&prodid=345226331032419

Unshreddable, even w/the biggest 29mm out there, it'd be practically indestructible on landing w/even the smallest streamer. It was DESIGNED for what this thread is all about!!
 

Estimado

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Umm...how on earth does streamer recovery vs. chute affect the aesthetics of a rocket? ANY rocket?

I know it's not super cheap. but I'd think the best high-altitude, single deploy option w/out a tracker would be Wildman's new Blackhawk: http://wildmanrocketry.com/default.asp?groupid=1&groupid1=612121482&prodid=345226331032419

Unshreddable, even w/the biggest 29mm out there, it'd be practically indestructible on landing w/even the smallest streamer. It was DESIGNED for what this thread is all about!!
Hi Deandome,
Thanks for the reply. I was speaking about the aesthetics/beauty of the rocket recovery itself, not the rocket. It's just my personal preference to see a rocket coming down on a parachute rather than a streamer.

The Blackhawk looks like a great rocket. I'll check it out. thanks for the link.
Rich
 
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