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barefootcyborg5000
barefootcyborg5000 PowerDork
3/24/22 5:03 p.m.

I still haven't taken the plunge, but I still generally take out little bros car when I visit. From the last outing:

Just not sure the expense would be worth it since I tend to lose interest in things pretty fast. 

RedGT
RedGT Dork
3/24/22 5:13 p.m.

Buy a used one and it'll resell for 'about what you paid' if you lose interest.

adam525i
adam525i Dork
3/24/22 11:19 p.m.
RedGT said:

I figure this could use a bump.  I got back into RC in 2020 when i bought a used slash and discovered the current state of the hobby with brushless/lipo technology.  WOW.  Ran that intermittently for about 2 years and it has taken a TON of abuse like a champ.  Then this winter i started going a little further down the rabbit hole - my daughter now has a rustler she loves, I have rehabbed a few cheap marketplace cars, built one for a friend's kid, and bought a Miata-bodied touring car to build a clone of my autox car.  It's been relaxing working on something small, contained, cheap, and not-rusty.  Being able to just buy whatever parts I want/need without breaking the budget is a nice change of pace from real vehicles.

 

Then I dug my old 1999 Rustler out of the basement, bought the cheapest used 4000kv motor & 3s ESC that i could find, and started seeing how fast I can get it going by doing a speed run, seeing what the limiting factor is, and only addressing that issue as cheaply as possible.  I started with the car exactly as i had put it away back in like 2002.  Only fix the current limiting factor each run.  Rinse and repeat.  It has actually been really fun taking this approach, not to mention a challenge getting a floppy 2wd open-diff non-TSC car up to speed in the first place.  To make a long story short, after a few iterations, the project is currently sitting at 64.9 mph and I am working on aero solutions because that's when it achieves liftoff.  Also I only ponied up for (2) modern belted tires for the rear and might have to give in and buy fronts too but I have a few more old ones to test first.  The ballooning is hard to manage.  But, in line with the philosophy, it's not the limiting factor yet, the 'taking flight' part is so i'll address that first.

My first RC car was a Rustler VXL with the stock brushless system (still have it, but I did a chasiss stretch and now it is a short course truck) so I could run my 3 cell Lipo's that I had for my heli in it. It was crazy how fast and uncontrollable it was lol. A tight body like that should really help at high speed, maybe run some velcro along the bottom edge to keep it from flaring out and catching air?

RedGT
RedGT Dork
3/25/22 7:00 a.m.

In reply to adam525i :

Good idea on the velcro, will try that next if it's a problem.  However for this current iteration... i might have gone overboard on the front downforce.   

slefain
slefain PowerDork
3/25/22 9:21 a.m.

In reply to barefootcyborg5000 :

The Ridgerock is a perfect crawler for someone who just wants to muck about. I picked one up for $100 a few years ago and it is awesomely capable. I let my kids drive it, but when I want to try some technical stuff it is impressive. I may slap a different body on it one day, but for now it is perfect stock. I run a 3000mAh battery in mine and only have to recharge it every few weeks of play.

RedGT
RedGT Dork
3/25/22 2:33 p.m.

Downforce is great.  Possibly too good.  It's much more stable now, and hit a new 'high score' of 66.2 mph.  Also those tires were glued 20 years ago and around 65 mph they flew off the rims.  Acceleration plateau'd more heavily in the mid 60's than before - unsure if there's too much drag for the motor's torque now or if that was a side effect of the tires preparing for departure.  Re-glued the tires but ran out of time on a quick lunch break.

 

Appleseed
Appleseed MegaDork
3/25/22 7:14 p.m.

In reply to RedGT :

You need foam tires and a full body. Open wheels are drag monsters. I believe you're hitting open wheel terminal velocity. Which in its own way,  is rad.

barefootcyborg5000
barefootcyborg5000 PowerDork
3/25/22 7:19 p.m.

Sounds like an RC centrifuge. Math out that 62mph with those 2" tires and the speeds are gonna be gnarly. I don't know the fix. I do remember a neighbor with a 2 speed jobber that ran on nitro from a can and it would do a claimed 80mph. Not sure what that setup was, other than really cool when I was 15. 

RedGT
RedGT Dork
3/25/22 9:41 p.m.

The rear tires are belted and supposedly good for 90 mph.  Nothing else on this old truck is though.

 

You can plunk down $500 and buy a new rustler that 'does 70+ with optional gearing!!!11' so i figure there's a little more speed to be had with the open wheels and a truggy body.  Or maybe the marketing is a sham.

adam525i
adam525i Dork
3/26/22 8:53 a.m.

In reply to RedGT :

My experience with the 'does 70+ with optional gearing!!!11' was that the car was in the air long before it got there with the stock setup but that was part of the fun (and traxxas plan to sell you replacement parts lol).

RedGT
RedGT Dork
4/5/22 2:12 p.m.

Got to 68 mph and it seems like the 4000kv motor on 3s with 100mph gearing is stagnating around there, whether due to motor RPM limit, battery discharge rate or simply not having enough torque to push the wings through the air.

I had not previously tried the buggy body and lowered stance without wings - went straight from the stadium truck body to buggy body w/ aero.  So I ran it wingless today to see if the aero was overkill.

No, the aero was not overkill.  The aero was very much still needed.  While it didn't take off and fly like it used to, it did get the nose in the air enough to enter a flat spin and caught a small tree while out of control, breaking lots of stuff.  Oh well, that means it is time to use the parts truck i bought about 20 years ago and never did anything with.  How convenient!

Since this also means the aero is needed, the limiting factor appears to be the motor's torque so I ordered a chinese 2250kv motor.  Have a 6S battery and appropriate speed control that were with a parts truck I bought recently so the GRM challenge style budget for this stupid project remains under $200

RedGT
RedGT Dork
4/11/22 10:13 a.m.

6s / 2250kv.  76.6 mph, still pulling, and then a delrin trans gear blew up.  Rebuilding with all steel.  That will be more mass but hopefully also more durability.

Found a better section of pavement to run, cleaner with more grip.  Acceleration is till tricky but the grip will support around 3.7 second 0-60 times now and that is hamstrung by having to be so gentle on the launch.  30mph-60mph (autocross benchmark i have a ton of data on) is now faster than a C6 Z06 on hoosiers so that's neat.

stroker
stroker UberDork
4/11/22 10:31 a.m.

Way, way back in 1977/78 I bought an eight channel radio control intending to get into R/C.  I never did.  I have an electric car of some kind (240z?) that I've never run.  I think the brand of the radio was a "Royale"...?  Would that have any value in today's market?  

RedGT
RedGT Dork
4/11/22 10:59 a.m.

That's old enough it may have vintage/collector value.  Pics would be really cool to figure out what exactly it is.

stroker
stroker UberDork
4/11/22 11:20 a.m.

In reply to RedGT :

I bought it used, so it wouldn't surprise me if it's late 60s vintage but I don't think the technology was up to that level then...

 

RedGT
RedGT Dork
4/18/22 10:17 a.m.

83.5 mph.  I thought this was cool...the little steel pins that hold the axle stub shafts into the plastic driveshafts started walking outward (see white stress mark, that's the pin trying to escape thru the wall) from the centripetal force of this whole thing, allowing the axles to fall out:

I drilled the axles and shafts to accept some extra wheel hex pins and went back for a few more runs.

But later in the day it had gotten really windy and the car kept getting blown off course around 80 mph until finally it almost took out my ankles and the RX8 at 81 mph and I called it a day.  Panic steering inputs from the near miss resulted in a barrel roll so there's also some damage repair to do.

fatallightning
fatallightning Reader
4/20/22 11:41 a.m.

That's brisk. A couple buddies have built no prep drag cars ostensibly Traxxas Slash based, but it's definitely a scene.

tuna55
tuna55 MegaDork
4/22/22 5:29 p.m.

 

Yes it's a screenshot. I'm not putting the movie up just yet.

 

I finally got this thing in the air today a few times, I've owned it since 1999 or so. It's powered by an os 40, and really only briefly. I spent 45 minutes trying to get the thing to run and maybe five in the air through a few flights.  The engine cut out three of four flights. 

 

What's the hot ticket for a cheap electric conversion? Can I buy take off stuff from a guy upgrading to brushless or something?

 

 

tuna55
tuna55 MegaDork
4/25/22 10:01 a.m.
tuna55 said:

 

Yes it's a screenshot. I'm not putting the movie up just yet.

 

I finally got this thing in the air today a few times, I've owned it since 1999 or so. It's powered by an os 40, and really only briefly. I spent 45 minutes trying to get the thing to run and maybe five in the air through a few flights.  The engine cut out three of four flights. 

 

What's the hot ticket for a cheap electric conversion? Can I buy take off stuff from a guy upgrading to brushless or something?

 

 

The cameraman (Tunakid #2) didn't get a great video. I can post some of it, but it doesn't show much. Mostly his running around and looking at the ground, making wiseacre remarks.

Flight #1 was decent, after fiddling for a long time (15 minutes) with the engine. I flew it around, and it porpoised pretty badly. It was really happy level and turning left once I got it trimmed nicely. The engine died, and I got it down. The propensity to be way happier turning left than right made it hard to hit the runway, so I set it down pretty decently in the dirt. Flight #2 was much more solid. I still noticed the right/left disparity, but did OK with it. This time it wasn't the engine's fault as I flew it behind the car trying to line up the runway, so it gently settled in the dirt once again. Flight #3 maybe wasn't a flight, as the engine died on rotation, and I only maybe got all three wheels off the ground. Flight #4 got it 20 feet up and then died, coming down hard and ending the day.

 

So... what's the cheap ticket for electic conversion?

 

The last flight
 

 

tuna55
tuna55 MegaDork
4/25/22 10:57 a.m.
tuna55
tuna55 MegaDork
4/25/22 11:28 a.m.
Appleseed
Appleseed MegaDork
4/25/22 1:22 p.m.

I would Google .40 brushless conversion. You can't be the only person converting.

If you get that sorted, and are looking for batteries ,  I found a cheap place. RCBattery.com. one of the guys who started HobbyKing ventured out on his own. Batteries are very inexpensive. The 1300MaH 3 cell lipos I got for my Slowstick were about $50-$60 10 years ago. Same size batt is $9.

tuna55
tuna55 MegaDork
4/25/22 1:39 p.m.
Appleseed said:

I would Google .40 brushless conversion. You can't be the only person converting.

If you get that sorted, and are looking for batteries ,  I found a cheao place. RCBattery.com. one of the guys who started HobbyKing ventured out on his own. Batteries are very inexpensive. The 1300MaH 3 cell lipos I got for my Slowstick were about $50-$60 10 years ago. Same size batt is $9.

I tried just randomly googling, but found outdated and expensive nearly exclusively. I know GRM is better than anyplace else, so I hoped someone had an idea here.

Appleseed
Appleseed MegaDork
4/25/22 2:18 p.m.

Use that old info to see if you can narrow down what size motor. Then take that size and shop around. Most places that sell motors also have appropriate speed controls that can be use with them. Once you get that, then you can size your batteries.

From what I can tell, you need a 800 watt brushless. I, personally, would buy from a North American outfit. Direct from China might be cheaper, but if there is any kind of issue you might be up the creek. E-Flight, Hobbyking or Tower Hobbies is probably a good place to start.

adam525i
adam525i Dork
4/25/22 10:59 p.m.

I'm pretty outdated at this point but all of my stuff (Heli's and Airplanes along with cars) was all brushless running Lipo's and that is the way to go for an electric airplane. Hobbyking was my go to for all of that back then, looks like RCBattery could be a good place for just the batteries and chargers. Keep in mind that it is a system you are putting together, the motor needs to be sized for the power you need but the also for the voltage (number of cells) of the batteries you plan on using. The brushless motors are known as outrunner motors as the coils are stationary and mounted in the middle with the outside casing spinning with permanent magnets mounted on the inside of it, it's kind of like an inside out normal motor but they deliver even better torque to spin over a prop without any gear reduction (I'm commissioning a farm right now that has fans that use this same concept at a much larger scale with a 51" diameter fan blade directly mounted to a large DC brushless outrunner motor).

I think a good place to start to give you an idea on sizing is to look at the ready to fly offerings of a similar size and weight and see what motor size (size and kv), ESC size (amps and number of cells they are rated for) and the recommended battery size should give you a good place to start. 

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