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Old 11-26-2018, 12:14 PM   #1
AHR43
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backyard grasstrack

Spent yesterday afternoon raking the back corner of the yard in an attempt to recover the r/c crawling course for eventual re-build. Sold my crawlers, so will level it out to a rocky plateau to navigate the ST over.

During all this, got to thinking the only way I'll get any r/c in any more is to build a back yard track. Jumps and whoops are too hard to mow around and over, so settled on a grass track similar to the tracks the British developed for m/c racing:

https://en.wikipedia.org/wiki/Grasstrack

Basically a trapezoid shape, two long corners with two straights of differing lengths. With the room available, thinking a 1/10 2WD buggy is best, but will validate the build with my ST, as it is all I have at the moment. Come summer, just scalp the grass for the course and leave the rest of the yard long. That should define the course without a need for markers.

Wondering if anyone else has experience running a back yard grass track? Seems easy enough, but there are always pop-up challenges and the unexpected to deal with.

Personal note: Grass track scrambles is where I began my romance with motor sports back in the late 1950's. In a way, be like going home again...

Cheers. AC
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Old 11-27-2018, 07:46 AM   #2
Need4Speed
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Check out Trackmate for a relatively inexpensive timing system, it has stood the test of time for me and is very accurate!
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Old 11-27-2018, 11:25 AM   #3
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Quote:
Originally Posted by Need4Speed View Post
Check out Trackmate for a relatively inexpensive timing system, it has stood the test of time for me and is very accurate!
O.K., Bill. I will bookmark it as a possible. My backyard is an AT&T, electrical and natural gas easement. You can understand my reluctance to dig in the back yard to bury a timing system...

For now, looking to my old school manual stopwatch. Usual grasstrack sprint is four laps. Should give me the consistency I need to gauge improvements in lap times.

My ST's are running 4200 / 4400 Lipo's now. Thinking for a buggy on a four lap short course sprint I can drop down to a ~3500mAh, as long as I keep the C at 65 or so. Should give me the run time and punch a buggy will need for this course? What think? Maybe even lower to a 3000? Less mAh=less weight for sprints?

Thanks for looking in and commenting. Cheers. AC
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Old 11-27-2018, 01:17 PM   #4
Need4Speed
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Trackmate uses IR which is a lot less expensive, instead of burying wires, you need to build a PVC bridge to hang the IR sensors above the track, you can see my setup in this video here to get a better idea of how it works:
https://www.youtube.com/watch?v=No_nkkx3l88

I'm not very familiar with oval racing, though I have found when migrating from clay to the higher traction turf track at Thornhill, higher capacity (heavier) packs tend to provide more punch and faster lap times in the stock classes. Most folks have migrated to LiHV packs which tend to produce the lowest IR possible which yields the best performance. Most chargers these days come with IR meters to help you check the health of your cells. Most of my cells start out with a reading around 1mΩ and then performance starts to degrade after 6mo to a year when the cells hit around 7mΩ, I have seen most cells start to show signs of swelling at around 14mΩ.
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Old 11-29-2018, 08:57 AM   #5
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Paced off the track location this morning. 8 x 20 paces = ~16ft W x 40ft L. Tight track. Should make for some sideways power sliding action.

Bill, thanks for the battery walk-thru. I have a second GT10 that will get conversion to brushless. Thinking a 17.5 on 3s will give me what I need. Have a LiHV Shorty wish listed. My sources tell me I can charge a LiHV with a LiPo charger, albeit, pack voltage will be a tad down.

In keeping with the British tradition of grasstrack racing, looking to spring track opening dedication, on or about March 20, the Vernal Equinox. Looking to get some hot laps in before that, but that will be the day the Union Jack gets hoisted over the track, paired, of course, with the Republic of Texas flag.

Cheers. AC
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arnie hauswald racing 1943
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Old 11-29-2018, 09:07 AM   #6
Need4Speed
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Sounds like fun Arnie!

Something I just realized in my last response was that I used IR for 2 different meanings... when talking about the Trackmate timing system, IR = Infrared, the IR signal can pass through a clear window or light opaque colors... the IR signals have trouble going through solid dark colors on the lexan bodies.

When talking about batteries, IR = Internal Resistance. Most clubs restrict to 2S at 8.4V max and LIHV will typically offer considerably longer longevity when charged to 4.2V/cell instead of 4.35V/cell.

Instead of 3S on 17.5T, I would consider going with a 6.5T on 2S so that if you ever run at a different track, then you won't catch any flack for running something above 8.4V.
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Old 12-06-2018, 02:28 PM   #7
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Greetings, mates. Did a scalp cut with the lawn mower couple of days ago to better define what the track will look like. Pictures show a a shading difference and a slight grass berm by looking closely. Lane width is ~ 30", give or take.

Did a static throw-down today. Looks workable. Wanted to get some hot laps in with the 2s 17.5 blue/silver ST, but rain is now precluding testing. Thinking the black ST roller will go 3s 13.5, but need some 2s baseline runs first.

View from the VIP spectator seating on the porch shows good definition on corner 2. Two standing cones at entry to corner 3 mark an on-track tree root hazard; one standing and one lay-down cone on the front straight mark the off-track concrete drain spout hazard.

Drivers stand will be outside corner 3, where the two standing cones are now.

Definition cut is encouraging. Progressing nicely. Cheers. AC
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Old 12-06-2018, 03:19 PM   #8
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nice, very tempted to do this on my side yard, but wife would probably kill me if I did!
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Old 12-06-2018, 08:12 PM   #9
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Check signature block below. I did a backyard track a few years ago. Didn't do any timing system or anything , just had a blast with some friends. Used garden hoses for lane dividers and various pots as some keep ya honest in the corners devices. Built s couple wood ramps.
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Back Yard Track...Lockhart Area Grass Track
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Old 12-07-2018, 03:15 PM   #10
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How cool is your grasstrack, RockinG. It's a 'big un' too. Great vid; great action. Is it still active? Thanks for the post up.

Mine will be primarily a flat track. Am entertaining the ST option of introducing a wood lattice panel on one straight (rumble strip) and a small 4" jump on the other straight.

Cheers. AC
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Old 12-07-2018, 06:22 PM   #11
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No sir, I have since moved. It was a lot of fun though. Sure allowed me to scratch the RC itch anytime I needed to. Was only able to run it during the winter when the grass was dormant.
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Old 12-23-2018, 01:12 PM   #12
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Concept works

Put in 24 laps with the 17.5T 2S ST just now. Did a scalp cut with the lawn mower over the beta oval I cut about three weeks ago. Will need a driver stand, though. Thinking 18" height will do the trick. Will need some flex tubing to deflect the car away from the gas meter and a tree. Other than that, no other apparent obstacles of concern.

17.5T Novak Ballistic brushless and old Novak ESC both run dead cool. Gearing is standard AE nitro ST 32P. 2S x 4200mAh Lipo gives good snap off the corner. So for now set up stays as is. Will remove the ESC fan. Pine needle jammed it early on. Won't need a fan for four-lap timed events anyhow.

Pix later as it begins to come together. Cheers. AC
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Old 12-27-2018, 10:40 AM   #13
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Minor Setback

Don't these utility people understand there is a r/c grasstrack being created here? Christmas Eve day a contractor came by armed to the teeth with warning flags of various colors and designs. Marching right along the back straight they are. AT&T fiber optic feed and house power feed. And scattered about are Comcast cable feed, natural gas feed and AT&T hard line. Buy a home on an easement? Not again, thank you very much.

Good news. RFI (Radio Frequency Interference) is a non-issue from the myriad electric and electronic fields floating about the back yard. "Mark" (that's the nickname I gave the guy marking the feeds) seemed knowledgeable and conversant in RFI, so tend to believe him.

Have a residential demolition service coming to give an estimate on removing the storage shed. There are reasons for removing the shed other than creating the r/c grasstrack, so, thankfully, that will not be a chargeable expense to the track.

Cheers. AC
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Old 01-06-2019, 05:38 PM   #14
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New Year Update

Storage building is gone. The final major impediment to realizing creation of a back yard track. Freeing up a lot of space, it enables me to extend the back straight by 3ft. Short, but significant, as it allows me to by-pass a massive tree root from corner 3 coming off the back straight. And, now, more than enough space for a small driver stand and pit pop-up.

Thanks for looking in and following this thread. Cheers. AC
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Old 01-06-2019, 10:48 PM   #15
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doesn't look like very many laps have been made yet, ha!
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