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Home✈️Aircraft🚁Helicoptere-AlignOther › T-Rex In-flight data video
07-21-2006 02:50 PM  14 years ago
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KamikaziRcPilot

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Cincinnati, OH

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T-Rex In-flight data video
I have the Eagle Tree Micro Power data logger. I purchased all of the sensors to go with it. I used a small piece of foam and a tie-wrap to secure the temp probe to the side of the motor. The foam keeps the ambient air away from the probe, so it's a good assessment of the motor temp. The RPM sensor picks up the main rotor speed. I flew it last night while my son video taped. I then captured a small video of the data captured and inset that into the flight video. It's neat to see what's happening to the heli during flight.

Here's a link to the video:

http://www.youtube.com/watch?v=AmR0oGtvT08

I set the zoom level before handing the camera to my son, so the smallness of the heli is my fault. I also need to experiment with different settings on the data capture so that it's more clear. I'm going to work heavily with it this weekend.
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07-21-2006 05:52 PM  14 years ago
glucoseboy

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Looking forward to seeing the video. I've had my eye on that eagletree logger for a while now.

Are you using magnets or optical to get the headspeed readings?

Was it easy to install?

Thanks!
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07-21-2006 06:02 PM  14 years ago
KamikaziRcPilot

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I purchased both rpm sensors but mounted the magnetic one on the T-Rex. The optical sensor needs whatever surface you're pointing the sensor at to be 180 degrees of black and 180 degrees of white. I've heard of some guys painting half of the top of the main gear, or glueing a ring of stiff paper to the top of the gear. That seemed like too much of a hassle, plus I read reports of certain lighting conditions causing it not to work properly.

I used a small piece of clear plastic packaging, like the type used to package cell phone accessories that you have to cut the welded seam off to get it open. I made a tiny mount and Shoe-Goo'd the sensor to it. I mounted it using an existing screw on one of the servo mounts. The sensor needs to be within 1-2mm of the magnet, which I mounted in the extra hole in the aluminum collar on the main shaft. I lightly enlarged the hole just deep enough for the magnet. I removed as little of the aluminum as possible so as not to weaken the collar.

My first capture of data contained a lot of really high spikes, but a recent firmware upgrade resolved that issue. Eagle Tree has been great to work with!
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07-21-2006 06:16 PM  14 years ago
glucoseboy

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Thanks for the detailed mounting instructions. I was leaning towards magnetic sensors as they seemed simpler to install and less prone to error.
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07-21-2006 08:28 PM  14 years ago
KamikaziRcPilot

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I just posted the video on "YouTube". Try the link above now...
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07-21-2006 09:09 PM  14 years ago
glucoseboy

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OK, I'm sold! I love how you overlayed the display onto the video of your flight. In addition to checking out how well component set ups work, seems like a great training tool to learn better collective management skills.

Now, where did I put my credit card???

Thanks for posting!
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07-21-2006 10:15 PM  14 years ago
ptarp

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Can anyone post a picture of how you installed the RPM sensor?
Philip
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07-21-2006 11:13 PM  14 years ago
Boidman (RIP)

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The Home Stretch

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Poor quality images, but may shed some light on one method.

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07-21-2006 11:53 PM  14 years ago
colin8

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Phoenix, AZ

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I recorded the data and provided a graph of my T-Rex with a Hacker A20-6XL here: http://www.runryder.com/t266853p1/

I didn't buy any of the sensors, was just interested in the current draw during flight. I did find it interesting in watching your video that the temperature of the motor steadily increased throughout the flight and there were no significant drops in temperature even during low loading of the motor.

These data recorders provide a lot of good info. Thanks for posting your data. BTW: What motor, battery and pinion are you running?

--Colin--
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07-22-2006 12:17 AM  14 years ago
KamikaziRcPilot

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Cincinnati, OH

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I'm running the Medusa 28-32-3400 with a 13T from a TP1320 3S pack.

After doing some research, I'm thinking of switching to a 12T or even 11T pinion and increase the throttle, as I'm only running a max of 80% in my thottle curves. This means that the mosfets are doing more work than they should. The closer to 100% you can get, the less the mosfets needs to switch to limit the current. With running TP1320's, they can't put out the juice as readily as the 2100's, so I don't plan to take the headspeed above 2700 or 2800 rpm's max.

I never expected the motor temp to decrease during flight. The Medusa 3400 is a sealed motor, lacking the vents the Align 430L has. I picked up a second Align gold heat sink. I'm going to modify the two sinks so that they'll both snap onto the motor. I'll snap them on from the sides rather than front and back so that the longer fins are sticking out the side of the frame for added cooling. I don't know how much difference it will make, but I like to experiment.
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07-22-2006 01:51 AM  14 years ago
ptarp

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Boidman: Is the sensor magnet on the bottom of the swash? Did you put a counter-weight on?
Philip
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07-22-2006 02:12 AM  14 years ago
Boidman (RIP)

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The stock mainshaft retaining collar is below the swash and directly above the upper bearing assembly. The empty screw hole side of the collar is visible in the picture. A second collar is just below the upper bearing and can be seen where the line from "collar & magnet" points down and to the right. The magnet is in the unused hole opposite the set screw. The mass of the magnet or set screw is so small and so near the center of rotation of the main shaft as to be insignificant, just as it does not matter that the upper collar is commonly retained with only one screw.
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07-22-2006 10:04 AM  14 years ago
TomRex

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West Palm Beach Join Date: 12-28-2005

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Comic kazi,
Try and put your tail servo on the other side of the boom and your gyro under the boom even if you have to flip the rear block over to avoid any servo/gyro damage/loss when you crash!
Ignorance is the absence of facts.Stupid is lacking the intellectual capacity to comprehend the fact
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07-22-2006 11:28 AM  14 years ago
gt900uk

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Scotland

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Looks good. Whats the thing with running 100% throttle curves though i just got a medusa motor and in the instructions it says to alter the pinion to get the HS you want at 75% throttle. Is this bad advise then?This Heli Will Self Destruct In Five Seconds!!
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07-22-2006 03:29 PM  14 years ago
KamikaziRcPilot

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Cincinnati, OH

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TomRex:

My tail servo's on the port side. I want to use a 3mm CF tube for the tail control rod to that I can eliminate the guide on the tail boom support. I just haven't gotten that far. Same deal on the gyro. Unlike the majority on these newsgroups, RC is but one small part of my life. I play a lot of soccer, do a lot of cycling, and roller blade as much as I can. My job is very demanding, so I just can't devote the time that others can. If you could figure out a way to add another 6 hours to each day, I'd greatly appreciate it!

GT900UK:

I'm not looking to run at 100% throttle, just closer to it to see if things run any cooler or more efficient. The thing I love most about this hobby is the chance to experiment and learn. One of the biggest things I've learned about T-Rex's, is that no two are alike. I tried a number of things recommended by others and received different results. I've only been in the RC hobby a couple of years, and I'm constantly reminded of how much I don't know...
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07-22-2006 05:07 PM  14 years ago
KamikaziRcPilot

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Cincinnati, OH

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Also, I believe the "75%" guideline is for if you're planning to use governor mode. I tried the governor mode on my CC35 with the 3400, and it would occasionally pulse the motor at times like it was hitting the low-voltage cutoff, but it wasn't, so I went back to using curves.
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07-23-2006 12:29 AM  14 years ago
Raptor3DPilot

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North Las Vegas, NV

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Yes definitely need to add a data logger to my wish list.. thanks for the video!Remember when flying inverted that down is up and up is EXPENSIVE!
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