WORLD WIDE WEB — It all began with an on-board video displaying a rocket's fluttering fins, but the offspring it produced would make any Frankenstein fan sit up and take notice. The brain-child of Drake "Doc" Dämerau, "Sense Ability" is a data acquisition rocket sporting more sensors than most lab projects.

Dameräu works at the Scranton Army Ammunition Plant, in Pennsylvania, which is operated by General Dynamics. There, they make artillery shells for the U.S. Army, Navy, Air Force, as well as NATO. As the chief metallurgist and laboratory director, he specializes in failure analysis, but is also responsible for all material specifications and testing.  As a Level 3-certified rocketeer, his career often crosses over into his hobby.

Detailed drawing of the extensive movable motor mount assembly which will house a pressure transducer and a load cell, measuring motor thrust through Mach transition.

"It started with an on-board video I saw of some unbelievable fin flutter," Dämerau said when asked about the birth of the project. "I immediately thought it would be cool to put strain gauges on the fins. With that, it would be interesting to be able to plot that flutter against something like airspeed acceleration through Mach transition."

The more Dameräu thought about the idea, the more he started looking into what it would take to do such a project.  "As repair techs and calibration personnel came into my lab, I picked their brains about the idea," Dameräu stated. "From that came all of the sensors I have now."

Dameräu has spent over three years collecting the sensors and transducers needed to build his data acquisition project.  "I'm getting close to acquiring all the big ticket items," Dameräu said while discussing all of the pieces it would take to put something like this together.

"One recent donation to the project was two on-board self-contained 6 channel temperature logging units that retail for over $8,000," Dameräu said. "With these units, I can measure motor case temperature, fin leading edge temperature while going through Mach transition, and of course, ambient temperature."

Most of the design of the rocket has already been completed, and the remaining parts are being collected to put it all together. One of the more difficult aspects was making a high-quality quick change motor mount assembly that could take any length motor, yet still house a pressure transducer and the load cell to measure motor thrust through Mach transition.

The only major components missing now are the regular rocketry parts, such as centering rings, airframe tubing and a nose cone.  Any individual or company interested in contributing these components should contact Dameräu directly, and sponsors will be recognized in the resulting analysis and reporting.

Dameräu is documenting the project on his website, RocketMaterials.org, the high power rocketry strength of materials testing website he operates to help fellow rocketeers understand how the components they pick can affect the way their rockets perform.  You can find the project online at: http://www.rocketmaterials.org/research/datarocket/

08-17-2008 08:57 PM  #1
UhClem Certified Level Three   Joined: Oct 2006 Posts: 192	Re: Article: Data acquisition rocket project making great strides $8,000 for temperature loggers? I guess I shouldn't explain just how cheap it would be to add thermocouple inputs to a Log-O-Matic.

08-18-2008 05:42 AM  #2
Doc L3CC Member   Joined: Sep 2006 Posts: 250	Re: Article: Data acquisition rocket project making great strides Quote: $8,000 for temperature loggers? I guess I shouldn't explain just how cheap it would be to add thermocouple inputs to a Log-O-Matic. It's not just logging numbers. These things are truly remarkable. The 8k is what both loggers cost. However, if you can add a thermocouple to the Log-O-Matic, we need to talk. The DataPaq loggers can only do type K thermocouples. I would like one channel to do a Type C Thermocouple. If it can, we can measure the motor exhaust temp. Type C goes up to 5,000°F. Doc

08-18-2008 09:11 AM  #3
GTpyro New Member   Joined: Aug 2008 Posts: 1	Re: Article: Data acquisition rocket project making great strides What other data logging options are out there aside from the RDAS units? I've been looking for several weeks and have not produced any fruitful results. I need something that will record at least 6 analog channels, but would prefer more.

08-18-2008 09:20 AM  #4
UncleVanya If pigs had fins...   Joined: Sep 2007 Posts: 3640	Re: Article: Data acquisition rocket project making great strides Quote: What other data logging options are out there aside from the RDAS units? I've been looking for several weeks and have not produced any fruitful results. I need something that will record at least 6 analog channels, but would prefer more. Read this thread it goes into great detail about the data logging rocket. In that thread there are a number of ideas for data logging tossed out. Note by Steve Shannon: At this point in the thread a discussion of fin flutter ensued. I moved that discussion here.

08-18-2008 06:45 PM  #5
Doc L3CC Member   Joined: Sep 2006 Posts: 250	Re: Article: Data acquisition rocket project making great strides Two of the fins going on the data rocket will have strain gages in a full Wheatstone bridge configuration. One will be a "control" fin that is designed to do well over Mach. The other fin with the strain gages is designed to flutter at a given speed and will be replaceable. If the fins bend backward on themselves, or even twitch, we'll record it in real time. I hope that this will prove/disprove any/all theories on HPR fin flutter and fin shreds. Doc

08-18-2008 07:48 PM  #6
UhClem Certified Level Three   Joined: Oct 2006 Posts: 192	Re: Article: Data acquisition rocket project making great strides Quote: It's not just logging numbers. These things are truly remarkable. The 8k is what both loggers cost. However, if you can add a thermocouple to the Log-O-Matic, we need to talk. The DataPaq loggers can only do type K thermocouples. I would like one channel to do a Type C Thermocouple. If it can, we can measure the motor exhaust temp. Type C goes up to 5,000°F. Doc If you can drill holes in an aluminium block and weld thermocouple wire to copper wire, you are in business. The "trick" is to embed the TC wire to copper transition inside a block of aluminium along with an absolute temperature sensor. The block keeps things at pretty much the same temperature which is why it is called an iso-thermal block. Feed the TC voltage to an instrumentation amp and the absolute sensor to another input and you are done. Multiple TC wires can be terminated in a single block of course. Much handier than dragging a beaker of ice water around with you. The welding is typically done using the same type of spot welder that is used to weld TC wire together to make sensors. Other connection methods are OK but welding is preferred. Care must be taken to insulate the wires and a high thermal conductivity epoxy to hold everything in place would be nice as well.

08-18-2008 07:49 PM  #7
Art Upton Space Cowboy   Joined: Aug 2006 Posts: 102	Re: Article: Data acquisition rocket project making great strides Quote: Two of the fins going on the data rocket will have strain gages in a full Wheatstone bridge configuration. One will be a "control" fin that is designed to do well over Mach. The other fin with the strain gages is designed to flutter at a given speed and will be replaceable. If the fins bend backward on themselves, or even twitch, we'll record it in real time. I hope that this will prove/disprove any/all theories on HPR fin flutter and fin shreds. Doc Hi Doc, That is a nice setup, I'm sure you will get to the bottom of these issues.

08-19-2008 05:27 AM  #8
Doc L3CC Member   Joined: Sep 2006 Posts: 250	Re: Article: Data acquisition rocket project making great strides Quote: If you can drill holes in an aluminium block and weld thermocouple wire to copper wire, you are in business. The "trick" is to embed the TC wire to copper transition inside a block of aluminium along with an absolute temperature sensor. The block keeps things at pretty much the same temperature which is why it is called an iso-thermal block. Feed the TC voltage to an instrumentation amp and the absolute sensor to another input and you are done. Multiple TC wires can be terminated in a single block of course. Much handier than dragging a beaker of ice water around with you. The welding is typically done using the same type of spot welder that is used to weld TC wire together to make sensors. Other connection methods are OK but welding is preferred. Care must be taken to insulate the wires and a high thermal conductivity epoxy to hold everything in place would be nice as well. I think you are talking about a cold junction here. I have Type C thermocouples (with cold junctions) so I don't need to make one. Type C are made from Tungsten with a splash of Rhenium to reduce the brittleness. One leg has more Rhenium then the other, producing the voltage. My problem with using the logomatic was not collecting the V out. It is with the nature of the output of thermocouples. They are not even close to linear. We would end up with a table of voltages, and no way to accurately convert them to temperatures.

08-19-2008 07:21 PM  #9
UhClem Certified Level Three   Joined: Oct 2006 Posts: 192	Re: Article: Data acquisition rocket project making great strides Quote: They are not even close to linear. We would end up with a table of voltages, and no way to accurately convert them to temperatures. I don't see how that is a problem. All of the data has to be converted from the raw ADC counts into engineering units and this is only slightly more complicated. Omega has a nice table of voltage to temperature (C or F) which can be used for the conversion. Or if that seems too old fashioned it can be fitted to a polynomial and that would be used for the conversion. http://www.omega.com/temperature/Z/pdf/z239-240.pdf http://www.omega.com/temperature/Z/pdf/z198-201.pdf

08-19-2008 07:53 PM  #10
Doc L3CC Member   Joined: Sep 2006 Posts: 250	Re: Article: Data acquisition rocket project making great strides Quote: I don't see how that is a problem. All of the data has to be converted from the raw ADC counts into engineering units and this is only slightly more complicated. Omega has a nice table of voltage to temperature (C or F) which can be used for the conversion. Or if that seems too old fashioned it can be fitted to a polynomial and that would be used for the conversion. http://www.omega.com/temperature/Z/pdf/z239-240.pdf http://www.omega.com/temperature/Z/pdf/z198-201.pdf How silly of me. ...and this is something we can do? (...and by "we" I obviously mean you)

08-19-2008 09:47 PM  #11
UhClem Certified Level Three   Joined: Oct 2006 Posts: 192	Re: Article: Data acquisition rocket project making great strides Quote: How silly of me. ...and this is something we can do? (...and by "we" I obviously mean you) It is something you can do. Record the data in ASCII mode, import into your favourite spreadsheet, mangle all you want. I prefer working in C but that is probably because I have been using it for 20+ years.

08-20-2008 04:46 AM  #12
Doc L3CC Member   Joined: Sep 2006 Posts: 250	Re: Article: Data acquisition rocket project making great strides Quote: It is something you can do. Record the data in ASCII mode, import into your favourite spreadsheet, mangle all you want. I prefer working in C but that is probably because I have been using it for 20+ years. OK, I CAN handle that. I can work in Q Basic.

08-20-2008 04:57 AM  #13
Doc L3CC Member   Joined: Sep 2006 Posts: 250	Re: Article: Data acquisition rocket project making great strides Quote: I don't see how that is a problem. All of the data has to be converted from the raw ADC counts into engineering units and this is only slightly more complicated. Omega has a nice table of voltage to temperature (C or F) which can be used for the conversion. Or if that seems too old fashioned it can be fitted to a polynomial and that would be used for the conversion. http://www.omega.com/temperature/Z/pdf/z239-240.pdf http://www.omega.com/temperature/Z/pdf/z198-201.pdf OK, so I'm looking at those Omega data sheets again. It shows Type C thermocouples going to 4208 °F. I know for a fact they are good to over 5,000 °F. The polynomial equations are not shown for Type C thermocouples. I can ask my guys at Datapaq if they have the data in the upper limit of a Type C thermocouple.

08-20-2008 07:25 PM  #14
UhClem Certified Level Three   Joined: Oct 2006 Posts: 192	Re: Article: Data acquisition rocket project making great strides Quote: OK, so I'm looking at those Omega data sheets again. It shows Type C thermocouples going to 4208 °F. I know for a fact they are good to over 5,000 °F. The polynomial equations are not shown for Type C thermocouples. I can ask my guys at Datapaq if they have the data in the upper limit of a Type C thermocouple. I checked the NIST web site and they have nothing on type C thermocouples. But if you can find tabular data for the temperature range you want, fitting it to a curve isn't hard to do.

08-20-2008 10:17 PM  #15
Sono_6 Certified Level Three   Joined: Jul 2008 Posts: 404	Re: Article: Data acquisition rocket project making great strides I'm way out of my league here, but I only see type C thermocouples rated for a Vacuum Atmosphere to 4200 degrees.??? http://www.omega.com/ppt/p...ref=XTA-W5R26&Nav=tema06 http://www.elettra.trieste...pectroscopy/docs/WRE.pdf Given the amount of smoke generated wouldn't it be carburizing/reducing? Or does the AP make it oxidizing? It's sure not a vacuum! A little bit here about approximating the readout beyond 4199f... *edit* So maybe this equation helps???? ftp://ftp.hartscientific.c...ts_and_thermocouples.pdf Jim Urrata -Data N00b-

08-21-2008 05:13 AM  #16
Doc L3CC Member   Joined: Sep 2006 Posts: 250	Re: Article: Data acquisition rocket project making great strides Quote: I'm way out of my league here, but I only see type C thermocouples rated for a Vacuum Atmosphere to 4200 degrees.??? http://www.omega.com/ppt/p...ref=XTA-W5R26&Nav=tema06 http://www.elettra.trieste...pectroscopy/docs/WRE.pdf Given the amount of smoke generated wouldn't it be carburizing/reducing? Or does the AP make it oxidizing? It's sure not a vacuum! A little bit here about approximating the readout beyond 4199f... *edit* So maybe this equation helps???? ftp://ftp.hartscientific.c...ts_and_thermocouples.pdf Jim Urrata -Data N00b- These are the ones I have in stock: http://www.omega.com/ppt/p...p?ref=T5R_T3R&Nav=tema02 The spec page says "All three thermocouple calibrations can be used to 2760°C 5000°F) in hydrogen or inert gas atmospheres and in a vacuum. " Yes, I know they will be toast. I hope to get one good full motor burn out of each one. Type C is the highest rated thermocouple I've seen.

08-21-2008 05:39 AM  #17
Doc L3CC Member   Joined: Sep 2006 Posts: 250	Re: Article: Data acquisition rocket project making great strides Quote: The spec page says "All three thermocouple calibrations can be used to 2760°C 5000°F) in hydrogen or inert gas atmospheres and in a vacuum. " OK, here's a stupid question: Does anyone know how hot a motor burns? If it's less than 4,200°F, the conversion problem is non existent. Doc

08-21-2008 10:02 AM  #18
rocketguy101 Frustrated Aero   Joined: Aug 2006 Posts: 38	Re: Article: Data acquisition rocket project making great strides Quote: OK, here's a stupid question: Does anyone know how hot a motor burns? If it's less than 4,200°F, the conversion problem is non existent. Doc Well if its any help, the Shuttle SRB burns 6000 deg F according to this presentation -- at least I hope thats the right link, as it keeps timing out on me--but I have looked at it (or similar) before, and that is the spec for the nozzle.

08-21-2008 11:45 AM  #19
aerostadt Certified Level Two   Joined: Feb 2007 Posts: 56	Re: Article: Data acquisition rocket project making great strides Shuttle propellant burns at about 5600 Deg.F or about 6100 Deg.R. Doc's idea on strain gauges sounds good. It will be interesting to get actual deflections, modal shapes, and frequencies. I found it hard to believe that G10 fins with short spans and long root chords with good fillets are leisurely flapping like flags in the breeze. Bob

08-21-2008 07:05 PM  #20
UhClem Certified Level Three   Joined: Oct 2006 Posts: 192	Re: Article: Data acquisition rocket project making great strides Quote: OK, here's a stupid question: Does anyone know how hot a motor burns? If it's less than 4,200°F, the conversion problem is non existent. Doc I know what you are asking, but it isn't the right question. The purpose of the nozzle is to convert the random thermal motion of the exhaust gases into something a bit more ordered. In the process the temperature drops. Dragging a random example from Rocket Propulsion Elements pg. 56 (sixth edition) T2 = T1 * (p2/p1)^((k-1)/k) p2/p1 (exit plane/combustion pressure) was 1/811.3, k (specific heat ratio) was 1.3, T1 was 2,800K and T2 was 597K So hanging a thermocouple in the exhaust will measure a temperature lower and potentially much lower than the combustion temperature.

08-21-2008 07:13 PM  #21
rocketguy101 Frustrated Aero   Joined: Aug 2006 Posts: 38	Re: Article: Data acquisition rocket project making great strides Quote: I know what you are asking, but it isn't the right question. The purpose of the nozzle is to convert the random thermal motion of the exhaust gases into something a bit more ordered. In the process the temperature drops. Dragging a random example from Rocket Propulsion Elements pg. 56 (sixth edition) T2 = T1 * (p2/p1)^((k-1)/k) p2/p1 (exit plane/combustion pressure) was 1/811.3, k (specific heat ratio) was 1.3, T1 was 2,800K and T2 was 597K So hanging a thermocouple in the exhaust will measure a temperature lower and potentially much lower than the combustion temperature. Yup, look at slide 28 of the SRB presentation I posted above the temp exiting the nozzle is about 2400 deg F

08-21-2008 08:21 PM  #22
Doc L3CC Member   Joined: Sep 2006 Posts: 250	Re: Article: Data acquisition rocket project making great strides Quote: Yup, look at slide 28 of the SRB presentation I posted above the temp exiting the nozzle is about 2400 deg F Hanging a thermocouple in the exhaust may not work very well. What I had planned on doing was having one in the motor case at/near the core near the top grain.

08-22-2008 10:17 AM  #23
jsdemar NAR/TRA L3   Joined: Oct 2006 Posts: 358	Re: Article: Data acquisition rocket project making great strides Quote: Hanging a thermocouple in the exhaust may not work very well. What I had planned on doing was having one in the motor case at/near the core near the top grain. I doubt the thermocouple will survive. The combustion gases are highly corrosive compared to measuring a latent heat source or a mild flame. I don't think there's much value in knowing the internal motor temperature. The outside case temperature near the nozzle/liner overlap is typically the hottest point with the greatest potential for damage to the case (and motor mount). -John D.

08-23-2008 05:38 AM  #24
Doc L3CC Member   Joined: Sep 2006 Posts: 250	Re: Article: Data acquisition rocket project making great strides Quote: I doubt the thermocouple will survive. The combustion gases are highly corrosive compared to measuring a latent heat source or a mild flame. I'm sure you are correct. I was just looking for another area to generate data. Thanks (to you and everyone that spoke up) for discussing this issue. Quote: I don't think there's much value in knowing the internal motor temperature. The outside case temperature near the nozzle/liner overlap is typically the hottest point with the greatest potential for damage to the case (and motor mount). -John D. This area will be well covered. I have a few channels dedicated for this very purpose on the DataPaq temperature logger. I will be recording the following temps: Ambient temperature - as a baseline Leading edge fin temperature - to record Mach heating Leading edge rail button temperature - to record Mach heating Three points on the motor case - to record case temperature Doc