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Mike Rappold

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About Mike Rappold

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    Beginner Boater

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    McKinney, TX

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  1. Mike Rappold

    Tuned Pipe Wave Velocity

    Tim, On the Eagle Tree logger, the thermocouple expansion board can handle two thermocouples. So you only need one of those. The thermocouples are up to you. I did not use the Eagle Tree ones but bought from another source. I used a thermocouple supply company. The EGT sensor with compression fitting from Eagle Tree seems to large to fit in the side of a thin walled tuned pipe - something to consider. The Cylinder head temp sensor is very similar to the one I use. The one I use is smaller in length eyelet. The cooling heads on the engines need to be modified to fit the eyelet and allow for the glow ignitor to fit around the glow plug. let me know if you need more details on this. I have never tried the pitot tube for speed measurement - have only used the GPS module. Also to backup what Lohring said about measuring EGT in the boat. I have not found EGT particularly useful as a tuning aid yet. The Cylinder Head Temp has been very useful. If I meter the water more/less to adjust the temp plus work the needle valve, this works the best. The EGT then becomes a secondary reference point - have to have the correct engine temp/needle first and then the EGT follows - if that makes sense. EngMod2T simulation program is powerful program but does have a learning curve. The program does have a glow ignition feature. I am using it on .21 RC drag car engines. Take data from the Eagle Tree logger to help feed some of the software inputs. Have not tried it on boat engines yet though. Mike
  2. Mike Rappold

    Tuned Pipe Wave Velocity

    Tim, No problem on the logger questions. Be glad to help. I do not use the real time telemetry. Instead after a run I download the data from the logger to a laptop. I then import the data file into an Excel spreadsheet that is more customized/easier to view than what Eagle Tree offers. I do not use the real time telemetry because it is too hard to watch the boat plus look down at a screen. For the engine rpm sensing, I use two magnets 180 degrees apart pressed into the engine's flywheel. With two magnets there are no balance issues. The magnets are pressed into a hole/pocket in the flywheel that is 0.125" dia x 0.067 deep. I use a small centerpunch to peen the edges of the holes in two places to "squish" the edges of the hole. This locks the magnets in place to prevent them from flying out. The rpm sensor is a hall effect senor. It is mounted in an aluminum bracket that is attached to the engine rail. The photo attached shows one of the flywheel magnets and the sensor mount. For cylinder head temp, I use a thermocouple soldered to an eyelet. The eyelet is the glow plug washer then. I wanted to get the thermocouple as close to the cylinder as possible. Using the eyelet/washer method has been a good repeatable location. For the boats the cylinder head temp has been one of the most valuable tuning aids. Changes to the cooling water amount can be measured. On the EGT, I use a brass screw/nut assembly to create a compression sleeve system to hold the thermocouple probe. The probe extends to the center of the pipe's diameter. For the logger itself, I use the logger plus the thermocouple expansion module. This is where the EGT and CHT thermocouples connect in my setup. I also have the GPS expander to measure speed. On the logger, the faster the logging rate the better - typically 20hz to 40 hz depending upon logger model used. Hope this helps. Mike
  3. Mike Rappold

    Tuned Pipe Wave Velocity

    I have my boats set up with an Eagle Tree system. I am measuring EGT and cylinder head temperature. An example using a MAC 67 with AB 67 pipe in an older 67 Eagle SG rigger running 60% Nitro I will typically see between 550 - 650 deg F EGT. This is when the boat is at wide open throttle. I am using a thermocouple located at the center of the pipe's diameter in the middle of the "barrel" section. The thermocouple is a 1/16" diameter - small as I could get to try and get a fast response. A data logger like a Eagle Tree is a great tool to learn more about what the boat/engine is doing on the water - but there is a learning curve and it does take some deciphering of the data at times. It does take the "guessing" at values away since you have actual data for items like engine rpm, temp, GPS speed, etc. Mike
  4. Mike Rappold


    What size engine are you trying to bore out? I have done a few 21 size car engines. Used a straight flute carbide drill then a small boring bar. The boring bar was tricky due to small size and wanting to chatter. Mike
  5. Mike Rappold

    Exhaust Gas Pressure inside Tuned Pipe?

    Jim, Thanks for the info. Gets me in the ballpark. What I am trying to do is figure out what range pressure sensor might be used with an Eagle Tree Data logger equipped with an analog to digital converter board. I want to measure the pipe pressure at wide open throttle and see the effects of a various stinger diameters. Mike
  6. How much pressure does the exhaust gas exert on the fuel tank pressure line? Has anyone put a pressure sensor on the tank pressure line for a 21 size engine? Mike
  7. Mike Rappold

    Extending the carb out?

    Lohring, Not sure I follow how the intake tuning formula is supposed to work. Can you explain farther? Mike
  8. Mike Rappold

    For sale ! Nitro racer must have items

    I will take the RCATs ingniter if still available. Let me know. Mike
  9. Mike Rappold

    For sale ! Nitro racer must have items

    I will take the RCATs glow driver if still available. Let me know. Mike
  10. Mike Rappold

    What is a flow meter

    Terry, Usually between 550 - 650 deg F once everything has warmed up. Mike
  11. Mike Rappold

    What is a flow meter

    Paul, The Eagle Tree logger (black box data logger version) comes with an RTD type of temperature sensor. This is intended to measure cylinder head temp by wrapping it around the head of an engine. The RTD sensor is only good to about 450 deg max. In order to measure Exhaust Gas temperature, Eagle Tree offers a thermocouple expander board. This allows you to connect a type K thermocouple - which goes up to something like 2000 deg. The expander board allows for two thermocouples. The type K thermocouples can be purchased from other companies that specialize in industrial type ones. I am using a 1/16" diameter thermocouple to measure exhaust gas temp in an 67 and 90 nitro application. The end of the thermocouple extends into the center of the tuned pipe to read the gas temperature. I have the thermocouple located right next to the tank pipe pressure tap. I have not found a smaller diameter than 1/16" that would work for the application. I am sure they exist - just have not found yet. The thermocouples I am using come from a company called Pyromation. I chose to locate the EGT sensor at the center of the tuned pipe (widest section) vs in the header to minimize flow disruptions - as you mention above. Hope this helps. Mike
  12. Mike Rappold

    Crankshaft Slug Material

    What is the best, or most economical, material to use for placing a weight slug in a crankshaft? I know tungsten is often used in full size crankshafts but looking at some of the crankshafts in 21 engines, it appears to be more like copper or bronze slug. Also how much press fit is required between the hole in the crank and the slug material? Thanks in advance. Mike
  13. Mike Rappold

    Need some CAD help?

    Terry, Inventor and SolidWorks are both 3D CAD programs. I have only looked at Inventor but use SolidWorks regularly. I have also done what you are referring to with drawing up a hull and using a CFD program evaluate. On the question of is one easier to use than another - I cannot really answer since my experience is only with SolidWorks. For SolidWorks, once you get the concept of solid modeling understood, it is then a matter of learning the program commands. Learning curve is not "hard" but long at times - if that makes sense. There are now lots of online videos that help too. Solid modeling is used for items like engines, hardware, etc. More of your basic flat surface type items. For modeling "curvy" shapes like some boat hulls, surface modeling gets used. This becomes harder and more frustrating at times. Each surface has to be drawn in 3D space. Once all the surfaces are drawn, they have to form a "watertight" object with no gaps/holes where surfaces meet. Once done, the object is converted from a surface model to a solid model and is ready for a 3D program. Probably not the best description but hopefully you get the idea. For the CFD part, I use SolidWorks Flow Simulation. There is a learning curve with CFD and I am no expert. Programs are becoming easier to use with more examples available, tutorials, setup wizards, etc. With CFD programs you can do 2D and 3D analysis. Just depends upon what you are after. 3D takes longer to run a simulation. Luckily I have access to SolidWorks and the CFD program through my work. The cost of each program is pretty significant. Same with the Autodesk products. Both offer educational versions at a much lower cost - if you are student. Be glad to answer any questions. Mike
  14. Mike Rappold

    Time to run some twins

    Julian, The 6.0V battery should help the GPS - at least that was my experience with it on my boats. Also make sure the unit is facing up as indicated on the unit. What version of logger are you using out of curiosity? I have used the Eagle Tree loggers for many years on several boats plus RC drag cars. Great tool once you start using it regularly. I did not like the Eagle Tree software's graph display so I use an Excel spreadsheet to graph it out instead. I use their software to download the run but then save if as a .cvs file to be read by Excel. This allows for more customized control. Can provide more details/examples if interested. Let me know if have questions. Mike
  15. Mike Rappold

    Time to run some twins

    Julian, Not sure of the exact issue you had with the Eagle Tree Systems GPS. Food for thought is I found the only way I could make it work was to limit the voltage it sees to no more than 6.0 VDC. If the battery pack was over 6.0V, the unit would either not work or give odd readings. To limit the voltage, I use a voltage regulator from MIP systems. Mike