View Full Version : 1/10 Crackerbox brushless build
OK, so I have these 1/10 scale crackerbox hulls that we are going to be building with some of the cubscouts. The boys are 8 years old and for most this is there first non-walmart electric boat. So, this is what I am looking at doing:
Edit: The ebay link got old, so here is where I have been buying them. Ebay, seller name is cyberport888 and go to his store. He has the 1700 and 3000 kv mystery outrunners with 30amp esc for $19 to $21 delivered.
Mystery 30 amp esc and D2836-1700 brushless outrunner motor for speed. On a 3s battery and a x431 plastic prop, I figure speeds should be around 20 mph or a little higher. (18,800 rpm no load)
The hulls are plastic, with a 8.5" x 11" kevlar/carbon inlay. Transom is 1/8" hard plywood and the front of the hull will be solid foam. Weight with hatch is about 12 oz.
Drive will be traditional solid shaft, but they will have a flex shaft coupler on them for ease of driveline install and to limit vibration. rudder on transom.
So, anyone offer any advice on if this will work? Locally, we will build them all the same and race them. Not out for top speed, just some fun on a 3 acre pond to teach the boys some skills. Would love some feedback. I do not know how these run with the Roar motors and 6 cells. What kind of speeds do they get verse run times. I know in race trim, blowovers are the main issue. I want them to have fun, but not be flipping them constantly.
Oh, I am donating the hulls to the other boys, should be able to keep building cost down to $100 or less with 2 batteries and a cheap lipo charger from HK. Two of the boys need radios, will be postin a WTB add for some 2ch AM radios.
Thank you to any who can offer advice,
Brian
Sounds like a great project, and I may be able to help with the 2 ch. AM radios...
Jon
bwells
02-11-2010, 11:43 PM
Good idea and you will have your hands full. Hope you will have some help if only a few sets of eyes to lookout for what can go wrong. They will be on their way to Eagle Scouts! You mentioned 3s and then 6 cell and then 2 batteries. Is the 2 batts 1 for a spare or in parallel. The 6 cell you mentioned I'm guessing NiMH as opposed to 3s in series. The ESC is 12volt so I think the 3s would be great once the kids learn to drive but maybe start them on the 7.2 NiMH to learn and then throw in the lipo and watch their eyes light up! Good luck and a good price on the ESC/motor combo. Keep us posted please
Good idea and you will have your hands full. Hope you will have some help if only a few sets of eyes to lookout for what can go wrong. They will be on their way to Eagle Scouts! You mentioned 3s and then 6 cell and then 2 batteries. Is the 2 batts 1 for a spare or in parallel. The 6 cell you mentioned I'm guessing NiMH as opposed to 3s in series. The ESC is 12volt so I think the 3s would be great once the kids learn to drive but maybe start them on the 7.2 NiMH to learn and then throw in the lipo and watch their eyes light up! Good luck and a good price on the ESC/motor combo. Keep us posted please
sorry about the confusing post.
I am planning on running these on 3s lipo. the IMPBA and NAMBA classes use 6 cell standard batteries, or 7.2v with a Roar legal brushed motor. I do NOT want to go brushed! Just wondering how fast those run in oval trim racing.
I want to build them and have two batteries, one for a spare for running time. Might need to parrallel them for ballast if needed to hold the boats down, no idea on how fast they might be.
I have plenty of 2s-2200 lipos, so for the first run or two could set them up that way, then give them thier 3s batteries!
Might have to watercool the ESC, that would be another good project for them.
Brian
damfurst
02-11-2010, 11:56 PM
Man Cubscouts was never like this when I was one. All I can remember doing was glueing burned out matches in a pattern and making something with glue and popcicle sticks. I may have a couple of 27am radios & receivers that I would donate if you need them. Just let me know.
bwells
02-12-2010, 12:03 AM
Brian, Okay, I understand. Did the crackerboxes have a turnfin in the keel towards the bow or was that the old drag boats? That might be a thought as opposed to 2 turnfins on the transom. These are flatbottoms, right?
Brian
Well, some of the boys seem to be getting bored, don't blame them really. There are all kinds of thier activities that we can center around these boats, even when it comes to safety and emergencies and how to react. Lots to teach from building models to art work on the hulls. When I showed them the boats, even thier dad's eyes sparkeled!
I have been watching and buying good 2ch am radios w/ rc for under $20 each, so if you can do that or better, I will take them.
The crackerbox is pretty flat. 6 3/8" wide with 3/16" deadrise per side. Not pancake flat, but pretty dang flat. They do have centrally mounted turn fins about midship also, nothing on the transom except basic trim tabs and a rudder.
thanks, Brian
wakeboardfusion
02-12-2010, 07:59 PM
where did you get the hulls at, or did you make them. This should be a great project. Man that motor and esc are cheap! I bet these boys will have big smiles on their faces. I remember one time we made sailboats and raced them in raingutters on sawhorses... Times have changed.
where did you get the hulls at, or did you make them. This should be a great project. Man that motor and esc are cheap! I bet these boys will have big smiles on their faces. I remember one time we made sailboats and raced them in raingutters on sawhorses... Times have changed.
I made them.
The rain gutter regata, have some of those little sail boats around still also. tomorrow is the pine wood derby race, should be fun.
bwells
02-12-2010, 09:56 PM
Use lots of graphite on those pinewood derby's
axles! Nice job on the boats, do you have any pics of the bottom?
Brian
Use lots of graphite on those pinewood derby's
axles! Nice job on the boats, do you have any pics of the bottom?
Brian
Well, cars didn't do so well. In fact, they were about 0.5 to 0.9 seconds slower this year than in the past. Worse we have ever done, but the kids had fun. Generally, one of my kids is in the top 3, but kinda waited to long to put them together, another chance next year.
Back to boats, here it is:
And how could one get one of these?? :w00t:
OK, the boys have been working on the boats a bit. Last week we cut the bottoms for the stuffing tubes and glued them in with CA and epoxy. They are 1/8" shafts with 5/32 brass bearings on each end in a larger 3/16"outside tube. To make the shafts, I threaded the prop end 5-40 for the nut, and drilled the other end out to .098 to .25" deep. I then glued a piece of .098 flex into the end so it will stick out of the stuffing tube and into the motor coupler. the shaft is located to allow up to a 35mm prop.
The motors are the mystery outrunners, 1700kv. Around 18k rpm on 3s lipo. The mount is simply bent aluminum. A turned a teflon washer to sit in front of the coupler. I may water cool the motor mount by attaching a piece of brass tubing to the bend section under the attachment bolts. It lines up nice and the flex will be nice and smooth running instead of a solid attachment or ujoint.
The esc's are now attached to aluminum plates with a water tube going through them. paste on the fets, pressed cooling plates onto that and then sealed in epoxy. should be nice and water tight. Not a whole lot of cooling, but these are not all out race boats. More of a crackerbox nascar setup!
Servo mounts are all done and ready to be epoxied into the hull. this week we should glue in the motors, the servos and hopefully we will cast the rudder brackets. I now need to vacuum form the hatches, that plug is done and hopefully works!
I have a few more batteries coming in to try out also, not sure if I will go cheap nicad or cheap lipo. Need to run one first.
the hulls are really strong with the kevlar and foam in them. Way overkill, but they are 8 year old boys!
Anyway, here are picks.
And how could one get one of these?? :w00t:
You have radios, I have an extra hull...... hmmm.......
If only there was some way to work that out.......:spy:
Brian
tiqueman
03-29-2010, 10:55 PM
Brian, now youve really got me wanting to build another one of these. I built one my junior year of high school ('92-93) as a Drafting project to enter into the state fair for the Technology Students Association (TSA) club. I found the plans in the back of a Boat Modler Mag that were about a 4"x 4" size. The project was, to learn how to accurately scale it up from that drawing and duplicate it in AutoCad. I learned how to accomplish that and built it. Lately Ive been thinking of building another as this was the first RC boat I had ever had that wasnt purchased at radio shack (or equiv.) Knowing what I know now, Id love to build another and right the things I made wrong... unfortunately, this boat took a hit while falling off a shelf years ago and cracked the port side. Theres is no glass or epoxy anywhere on it, except to glue things together.. and even most of that was just CA. I only ran it a hand ful of times before I got into gas boats.. but it was a cool little boat and I was pround of it no matter how it ran. Oh and I got 1st prize at the FL State fair that year. :w00t:
Not looking for a hull, but I will see if I can come up w/ a radio and rx to donate to the club for the kids... Ive got a lot of misc Am stuff lying around.. I will see if I can get anything to match up and work....
Keep up the good work.. I was thinking about doing a similar project in the neighborhood I live in and getting the kids to meet up at the clubhouse twice a week to build something.. probably not powered though... something they can wind race or just put a small brushed motor to a couple duracells or somethign and let it go across the pond (about 40 yrds that one is) next to the club house... I dunno, still too many thoughts before I approach the event coordinator about it......
-Scott
You have radios, I have an extra hull...... hmmm.......
If only there was some way to work that out.......:spy:
Brian
DEAL.
One radio, one hull. Two radios, hull with shaft and stuffing tube. Installation is not necessary, I know how to do that. (SORRY I still haven't looked. But I am going to first thing tomorrow... Now I have incentive)
I have a spare brushed system I could put in there.
Jon
I was thinking about doing a similar project in the neighborhood I live in and getting the kids to meet up at the clubhouse twice a week to build something.. probably not powered though... something they can wind race or just put a small brushed motor to a couple duracells or somethign and let it go across the pond (about 40 yrds that one is) next to the club house... I dunno, still too many thoughts before I approach the event coordinator about it......
-Scott
i remeber years back about hearing of a competition to see who can get a boat across a pond the quickest. Basic rules were no RC or control electronics, electric motors only, stuff like that. A simple vacuum formed v hull about 20" long would work great. A cheap brushed motor, on off switch, plastic prop, solid shaft drive, couple of batteries and a rudder.
As long as everybody is close in equipment, it can be competitive and fun.
Go for it!
tiqueman
03-29-2010, 11:45 PM
Brian, PM me your address.... nothin fancy, but they work and if the boys can use them, they are yours...
wizard122
03-30-2010, 12:43 AM
Wow I still have my MRP cracker box boat runs on 6 cell and roar brushed motor X431 prop not the fastest thing but fun to drive here are some photos. What rudder are you going to use I would use an Octra my friend had a wood home built boot that work very well with that set up he also had to add a skag to the bottom near the COG to get it to turn good also some trim tabs to help tune it better good luck can't wait to see finished boats:thumbup1:
Well, this project is centered around two principles. Do it as cheap as possible to get kids involved and to teach the boys how to make things. The cost of a RTR boat with a battery or two, radio and battery charger has to be well under $100! About $80 to $90 max.
So we are building our own rudders. I took an old bracket from a plastic rudder, might have been dpi or mrp, and it is set up to cast in RTV wednesday (my old rtv setup and got hard, so I am waiting for my next order to come in) Hopefully Thursday we will do urethane resin casting on the brackets.
We will then make the rudders. Thinking about a cast bracket with the rudder arm incorporated into it, a break away aluminum rudder blade.
Trim tabs will be simple bent aluminum sheet, two bolts each on the back. The skeg will be the same. Piece of thin aluminum through the bottom of the hull.
Should be nice boats. I want them to be slower than the ones I see racing as they are leaning to drive and I want them racing, not retrieving flipped boats. We can always speed them up later.
Help request section:
Wizard, could you post a couple of more pics on how your rudder works, it looks like it is a break away design, correct?
Tiqueman, I will definately take those radios, PM sent. Thank you.
If you decide to do a project with the boats, let me know. I can come up with a simple vee hull, glue the two parts together and they would have a blast! I will send a PM.
After this boat project, I am hoping to get the dads into a 1/16 hydro class! Set up similar with a cheap outrunner, 2s or 3s lipo, build what you want, limit the power train to a single motor and a scale solid shaft and scale rudder, small scale turn fin!
Brian
wizard122
03-30-2010, 09:01 AM
here you go hope this helps.:Peace_Sign:
peells
03-30-2010, 03:49 PM
Looks like fun for the scouts, keep them intrested
tiqueman
03-30-2010, 06:05 PM
Brian, radios have been sent... Enjoy! Also threw in a Servo Check PM for tracking.
Xfactor
03-30-2010, 07:57 PM
I have a similar task. My sister does work with foster kids and wanted me to teach a tech class to the kids. So boats is what we decided. Look at theese they just came in the mail today. Iwas worried about the quality. I recieved them today and to my surprise the were pretty nice fo 14.99 each. The only delima All the radios are on the same frequency I think. Im hoping ill be able to get away with installing diferent cystal sets in each boat. Im gonna try one and see. Ill figure something out. For mods we'll paint,step up the prop to some octura plastic ones or the other ones ose sells, change the cowls,and have fun.
xfactor, those look pretty nice. not bad for $15! i love the through bolted hardware. No need to through bolt it through stringers, just go to the hull!
For a lot of these kids, this will be great. We have been foster parents for over 5 years now, seen a lot in that time. i have learned a lot in that time :crying: Been a heck of a journey.
Thanks tiq, will get a package out to you also.
Brian
boat update:
Got the 2nd coat of epoxy on the speed controls, so they are now done and cured. Waiting for the connectors so I can do the solder work. I think tomorrow I will work on the trim tabs, center skeg and rudders some. Lots to do. Oh, I will also try vacuum forming the hatch covers tomorrow, ready to try the next plug.
Brian
OK, had a meeting the other night with the boys. One is bored already, but the dad's are interested now. How interested would the average 8 year old be in a demonstration on resin casting with RTV molds?
So we epoxied in the motor mount assembly and the servo assembly. Also got the trim tabs on. That and flashlight tag and running around. Boys that is, not the dad's.
I have decided to make our own kick up rudders. I took a bracket from a fixed one and cast it in rtv, then made new ones. Original is black, new are white. The aluminum pieces in the back are going to be the plug for the rudder mount. It will pivot on bolts in the transom bracket, the rudder will be 0.06" aluminum secured with one bolt so it will pivot if it hits something. I will post more pics when I get the next piece done.
also started to form the hatch covers and found a problem. when I form them, I get a nasty web between thier helmets. don't think I can prevent it, so I am going to glue them on the inside, fill it with 2 part foam and then trim the web out. Should look just fine.
tiqueman, got the radios, thank you. will have to get your stuff boxed up and shipped out. Don't be waiting for the UPS man just yet!
pics will be posted below, won't let me post them right now.
here are pics for last post
tiqueman
04-02-2010, 03:38 PM
tiqueman, got the radios, thank you. will have to get your stuff boxed up and shipped out. Don't be waiting for the UPS man just yet!
Glad you got em! Enjoy! :w00t:
Brian, no sweat. Take your time. I actually found a deal on a full set of SV hrdwr for it, for 35 shipped. Hopefully that will work out nicely on it. I recommend shipping it USPS.. its A LOT cheaper and just as fast if not faster than UPS. As long as the box is under, I think its 108" total dims added together, it goes standard shipping. I shipped a 32" Nitro boat w/ the outboard motor on it and electronics on a heavy wood stand in a 15x20x40 box for $17.00 to TX.... UPS wanted $85.00 :ThumbsDown01:
To control cost and minimize damage, I decided to make the rudders. Three parts: Transom bracket, pivot mount and the aluminum rudder blade that will kick up.
The transom mount is a simple casting. Drill four holes in it, two for mounting it to transom and two for the 3mm pivot screws
The rudder pivot mount is cast with a piece of aluminum in it to form the slot. The aluminum is then pulled out which leaves the slot for the rudder blade to slip into. This piece also has the rudder linkage horn molded on it. Need to drill a hole for the clevis and drill a hole down the middle of the bracket, then tap each end 3mm for the pivot bolts.
The rudder is .060 aluminum. It is slid into place and then the whole assembly is through drilled with a 1/8" drill bit. One 3mm bolt tightened down holds the rudder in place. If you hit something, it will allow the blade to kick back, but you will still have steering, just less of it.
they do need to be sanded up a bit, but I think it will work well. cost, pennies each. Just time and more time - but it was fun and a neat way to show others one solution to a problem.
Now to assemble one and get a boat running to test.
Brian
tiqueman
04-08-2010, 10:51 PM
That looks great Brian!
Rudder is on the back of the boat now. Fits well, kicks up and looks like it will work. Not sure on the urethane casting resin, seems a bit brittle. I think the stuff I am using is only 3000 psi. You can get better resins, or I could just use epoxy. Harder to do, takes longer but for the few I need to make, it would work.
Getting close to running. With a 3s-1800 battery, I am looking at a running weight of 1 lb, 13 oz and it is one solid boat with the urethane foam and kevlar reinforcement.
Brian
That looks great Brian!
I was looking at the hatch on my 18" mystic and it almost fits the 24" mono. I am going to do a cast of it and vacuum form some. I need one for mine as well as one to send with yours. The hull is ready to ship, but I want to send the hatch with it.
Trying to get some projects done and off the work bench!
Brian
tiqueman
04-08-2010, 11:55 PM
I was looking at the hatch on my 18" mystic and it almost fits the 24" mono. I am going to do a cast of it and vacuum form some. I need one for mine as well as one to send with yours. The hull is ready to ship, but I want to send the hatch with it.
Trying to get some projects done and off the work bench!
Brian
That sounds great. No rush.
Someday I want to learn how vaccum form. Actually vacuum bagging is what Id like to give a whirl. Ive got a friend trying to get me to start tryin, I just dont know where to begin. I soon hope to build a single canopy hatch for my BJ26. Theres one out that Kintec offers, but I dont really like it. Looks too "toyish". That will be my first project Ive ever built a mold, made a plug and established a part. At least, I hope all 3 steps go that well. :confused1:
That sounds great. No rush.
Someday I want to learn how vaccum form. Actually vacuum bagging is what Id like to give a whirl. Ive got a friend trying to get me to start tryin, I just dont know where to begin. I soon hope to build a single canopy hatch for my BJ26. Theres one out that Kintec offers, but I dont really like it. Looks too "toyish". That will be my first project Ive ever built a mold, made a plug and established a part. At least, I hope all 3 steps go that well. :confused1:
You can do some pretty incredible things with vacuum bagging. Keep in mind, you can get a very good layup just by hand if you take your time. I learned vacuum bagging back in 1990 working as grunt labor with the pattern model makers. Did some neat stuff for aerospace industry, LARGE molds. It is not that hard to do especially now with all the online videos available. I have made some very light boats in the past when fast electric was like our sport boats now due to battery weight and limitations.
I would like to build a larger vacuum former. Right now I am limited to 23" x 16" and that uses a 1/2" frame, so plastic is 22" x 15". Allow for a gap all the way around and 21" long is the max I can do. Just short of a 1/16 hydro :mad:
Lots of cool stuff out there to play with, just not enough time.
Brian
tiqueman
04-09-2010, 12:03 PM
Lots of cool stuff out there to play with, just not enough time.
Or in most cases.. Money
tiqueman, need to fire up the vacuum former still.
Big news, ran a cracker box tonight to test it out and it works! This is the most scratch built I have ever done. make a vacuum former, make the plugs, make the hull, make the break away rudder using a plug, RTV mold and urethane, servo mount, water proof and cool the ESC, make the drive shaft and couplers.... Wow!
Well, ran it with a 2s-2200 battery, X431 octura red prop. Ran fine, definately slower than a race set up but good for the kids. Might try a 3s-1800 tomorrow.
It ran well enough and was pulling 13 amps +/- 1 amp at full throttle, dropping off to about 5 amps as I slowed it to turn. It was running wet also, tabs were too low. Might go up to a 35mm prop also, but have to get the kids racing first!
Not bad for a $21 delivered motor and ESC! Total cost with a couple lipo's and charger, RTR with AM radio will be under $80. And about $1500 in labor! :bounce:
Brian
tiqueman
04-21-2010, 11:46 PM
tiqueman, need to fire up the vacuum former still.
Big news, ran a cracker box tonight to test it out and it works! This is the most scratch built I have ever done. make a vacuum former, make the plugs, make the hull, make the break away rudder using a plug, RTV mold and urethane, servo mount, water proof and cool the ESC, make the drive shaft and couplers.... Wow!
Well, ran it with a 2s-2200 battery, X431 octura red prop. Ran fine, definately slower than a race set up but good for the kids. Might try a 3s-1800 tomorrow.
It ran well enough and was pulling 13 amps +/- 1 amp at full throttle, dropping off to about 5 amps as I slowed it to turn. It was running wet also, tabs were too low. Might go up to a 35mm prop also, but have to get the kids racing first!
Not bad for a $21 delivered motor and ESC! Total cost with a couple lipo's and charger, RTR with AM radio will be under $80. And about $1500 in labor! :bounce:
Brian
Sounds good Brian. Thanks. I know youve been busy. No worries. Actually, Im gunna hit you up w/ a PM.. Ive got some ?s on something Im brain storming.... I think your the guy to talk to about it.
Get some vid up if you can. Id love to see one of these run!
OK, so it is a bit rough. 10 year old running the camera. At one point, he starts calling in artillery strikes..... :Praying:
QXOyF5-HHfQ
Attached is a screen shot of the eagle tree data. This is the 1700kv outrunner, 2s-2200 20c turnigy lipo and a red x431 plastic prop.
Top speed is in the 16.5 to 17.5mph range, perfect for kids learning.
amperage is spiking to 15 amps on acceleration, but bounces around an average of 11 amps it looks like. Considering the motor is rated for 28 and the esc is 3s-30, it should be a nice running boat with 3s and up to a 35mm prop. I do not know what the top speed of the roar powered boats are, but should be a good class boat.
tiqueman
04-22-2010, 03:15 PM
Brian, thats Tx looks nice! Hope everything went ok in Sector 6. :flashfire: :hide: :rofl:
forescott
04-22-2010, 10:10 PM
Still need more radios? I have a brand new am radio+receiver from an hpi savage flux I can donate.
Still need more radios? I have a brand new am radio+receiver from an hpi savage flux I can donate.
Well, epoxying the receivers I think I ruined one, doesn't power up anymore. so I could still use another radio.
what do you have and let me know how much please.
Thank you,
Brian
forescott
05-31-2010, 01:26 PM
Well, epoxying the receivers I think I ruined one, doesn't power up anymore. so I could still use another radio.
what do you have and let me know how much please.
Thank you,
Brian
PM sent
forescott
05-31-2010, 05:28 PM
Got shipping $$$ I'll send the radio tues. morning! Here is a pic.... on the waay left.
Well, we ran two of the boats tonight. I think the 7.2v nicads bit the dust, they had no power as in idle out, turn around and limp back to shore.
Went to the 2s-2200 lipo and 27mm plastic prop. Fun running, kids did fine running in the local pond at the park. Second set of batteries my oldest hit the fountain in the middle of the pond and flipped. Knocked the driveshaft loose, so his fun was done for the day as I did not bring allen wrenches.
The boats ran well, but they tend to dig the nose in some. I bent the tabs up on one boat and then it started hopping. Bent them back down and it went well. We had a ton of rain so it was a bit flooded and water was dirty. You could tell when you hit some weeds as the nose of the boat would dip and you would plow water until you stopped.
After that, I decided to try a 3s-2200 battery. CG is definately to far forward, the lipos are too light! I got it up on plane and going and then nailed it. It lept up, then the transom lifted from the prop thrust and the nose went under. In the blink of an eye it turned into a submarine!
these are great and the boys are learning. I need to teach them how to "bring it in". They would just hit the beach at full speed and it would slide 3' up onto the grass. Rudder kicks up and the skeg protects the prop. We had a chat about that!
Next time I will have to get a video. Also might try running 2p on the lipos to get more weight in the boat and cg back. Run time on one pack was about 18 minutes. Speed was about 80 to 90 mph.
OK, maybe mid to upper teens! It is only a 1700kv motor on 2s with a 27mm prop. It will fit a 35mm prop, so plenty more testing to do.
Brian
forescott
06-13-2010, 11:35 PM
Sounds cool! Did you get that radio I sent you Brian?
Sounds cool! Did you get that radio I sent you Brian?
yes I did, works perfectly. Thank you man! :hug1:
When we were running tonight, there was a guy there with his young daughter. We talked about the boats and what I was trying to do with getting a group together locally to run, build a boat for a parent child relationship builder. Talked about the boat and what the real cost was vs. what the cost of what we built. He seemed like he thought it was a good idea and walked on at the park.
As we were putting away our stuff, he came back and his daughter had a walmart $20 boat to see if she liked it. I gave him my contact info and told him she could run some of our stuff if she wanted next time to see if she liked the faster stuff. So maybe this will take off. Fostering parent relationships while building real life skills and having fun!
Brian
forescott
06-14-2010, 12:22 AM
Glad to help. I'll keep an eye on this thread and let you know if I can donate any other parts/batteries.
venom*one
06-14-2010, 09:20 PM
you have a pm sir...
Done, well, for now! Finished up the hatches tonight. I let the boys go with model paint and brushes on the hatch covers...... Yeah, gotta work on that!
Anyways, I added a strip of plastic in front of the hatch so the front end slips under it securing the front. Then, I used two servo horns with some 3mm bolts on the back to make a couple of pivot latches. Now no tape ( :banana: ) and the boys can open and close them alone. Teach them to launch and retrieve them and it should go well. Other than them being closer to the water, wet shoes, mud, falling in......:crying: What am I thinking!
I am happy how these turned out. I also think the brushless motors are going to be fantastic, and these have quite a bit of power. 2s and 27mm prop is good for them to learn on. 3s and 35mm capacity will give them plenty to advance towards and break stuff! I really didn't want a brushed motor that would have heat problems and need maintenance.
Thank you to all who have helped, supported and/or offered advice. It has been a fun start to a project that I hope takes off.
I will have to turn this into a running information thread now as we get performance numbers.
Brian and two of the four cubscouts. (Den leader with his project included as well!)
Got some more video on Saturday with the boys, will need to edit it and post some videos.
Started with some 2s-4800 lipos, still running the 27mm props on the 1700kv mystery's. Didn't work so well. The boats would run bow down and push water. Everynow and then they would start running drier and skipping, but then they would stick back down. I was hoping the weight of the 4800 lipo's would help plant the transom. Trim tabs were bent up to the point they were positive.
Brought them back in and went to the lighter 2200 packs. Ran better, but still would push a lot of water.
Then Charlie hit a cat tail underwater and busted his prop. The good news is the kick up rudders have been working perfectly! Once they kick up, you can still steer the boat since only the rudder kicks up and not the steering bracket.
So I took the old 27mm prop off and put on a 32mm prop. These are all the black plastic OSE props. Well, he put it in and punched it and almost lost the boat flipping over backwards! That definately changed things. Now it rides dry and skipping. Put a 30mm on the other boat and they had a blast, both ended up flipped a couple of times.
Now that I got the prop issue worked out, I will have to try the 2s-4800 again to see if the extra weight helps some.
Glad I went with these little cheap outrunners. Originally, someone on another forum suggested a 2860-3500kv motor on a 60 amp speed control. :eek:
I am telling you what, other than specified racing, I would ditch those brushed motors. No maintenance and they will run submerged with the epoxy sealing! :rockon2: That Mystery has plenty of power to get you into trouble. Will have to use the data logger to get rpm, speed and amps.
SzxTa0wJbbs
venom*one
06-28-2010, 12:20 PM
box headed your way...
poobs
07-24-2010, 11:31 AM
Great thread Brian ! Thanks for pointing it out to me. :)
tiqueman
07-27-2010, 10:44 PM
They look great Brian. Silly fun! Reminds me of my brushless Mini Rio... can get crazy real quick. Very well done.
poobs
07-30-2010, 08:11 PM
My son finally got to run his crackerbox today with the Ebay 1700 motor and 2S.
It has an old 431 plastic prop with a piece of blade missing.
It seemed as fast as the original car motor with 8 nicads - nice!!! :thumbup1:
My son finally got to run his crackerbox today with the Ebay 1700 motor and 2S.
It has an old 431 plastic prop with a piece of blade missing.
It seemed as fast as the original car motor with 8 nicads - nice!!! :thumbup1:
I am telling you, this motor is perfect for this boat. You can fit a 35mm prop on it also, and the motor handles it easily on 2s. heck, we were getting about 15 minutes of run time on a 2s-2200-20c turnigy, they are like $9 at HK! And if you want, bump it to 3s to really overpower it. Lots of fun for a power package of around $35! (motor, esc, bat)
You should get those couplers in a few days. Hope they work.
Brian
poobs
07-31-2010, 09:10 AM
I am telling you, this motor is perfect for this boat. You can fit a 35mm prop on it also, and the motor handles it easily on 2s. heck, we were getting about 15 minutes of run time on a 2s-2200-20c turnigy, they are like $9 at HK! And if you want, bump it to 3s to really overpower it. Lots of fun for a power package of around $35! (motor, esc, bat)
You should get those couplers in a few days. Hope they work.
Brian
I did not get that much run time out of mine but my kid loved it. Gotta check my battery and see if my one Li- po charger is working ok.
The motor was pretty hot too. :confused2:
That run time was with 8 and 10 year olds. So some full speed, some partial running, some laughing. Even at the average 12 amps at WOT, a 2200 Lipo should last 11 minutes.
I have not checked motor temps on it with my IR gauge. Will have to get back out and get some more info.
What size battery were you using and how long did it last?
Brian
poobs
07-31-2010, 04:36 PM
That run time was with 8 and 10 year olds. So some full speed, some partial running, some laughing. Even at the average 12 amps at WOT, a 2200 Lipo should last 11 minutes.
I have not checked motor temps on it with my IR gauge. Will have to get back out and get some more info.
What size battery were you using and how long did it last?
Brian
The battery that I used is a 2100Mah. 2S 20C.
Funny but it has already started to bulge out a bit :confused2:
venom*one
08-01-2010, 11:32 AM
I got mine in the mail the other day... the craftmanship on this is top notch... My first boat and I can wait to have it up and running... will post pics when its running... Thanks again Brian for a wonderful first boat...
Tj
I got mine in the mail the other day... the craftmanship on this is top notch... My first boat and I can wait to have it up and running... will post pics when its running... Thanks again Brian for a wonderful first boat...
Tj
glad you like it. I only wish it had been good enough that you can't wait to have it up and running! Or is that what you meant? :bounce:
Glad you like it, good luck and ask any questions you might have.
brian
venom*one
08-02-2010, 12:21 PM
yes that was a typo... cant wait...
First coats of paint are on... drying now...
poobs
08-02-2010, 07:37 PM
I just picked up a couple of props bym Aquacraft P/N AQUB7765
They are supposed to be 30mm x 1.65 pitch
What do you guys think of these props for the Cracker box on 2S ???
1.65 seems a bit high on pitch if it is dia x pitch. But if it is 1.65" of travel, then that is what I am running. 30mm x 1.4 = 42mm of travel or 1.65" of pitch. How about that, answered my own question.
Yep, those should work perfect. tonight the boys ran thiers again also. 2s-2200 with a 30mm x 1.4pitch (same as yours). the boats ran a nice 17mph on glass water while sipping about 12 amps at full speed. That is one nice running boat and everything is very cool when done. Not much stress for a 30A ESC or 28amp motor. Tabs were pretty level, maybe slightly down, battery all the way in back. They only flipped one boat once! Lots of potential left in the boat, but that is a fun speed for them right now.
Eagle tree graph of a couple of passes.
poobs
08-14-2010, 09:45 PM
1.65 seems a bit high on pitch if it is dia x pitch. But if it is 1.65" of travel, then that is what I am running. 30mm x 1.4 = 42mm of travel or 1.65" of pitch. How about that, answered my own question.
Yep, those should work perfect. tonight the boys ran thiers again also. 2s-2200 with a 30mm x 1.4pitch (same as yours). the boats ran a nice 17mph on glass water while sipping about 12 amps at full speed. That is one nice running boat and everything is very cool when done. Not much stress for a 30A ESC or 28amp motor. Tabs were pretty level, maybe slightly down, battery all the way in back. They only flipped one boat once! Lots of potential left in the boat, but that is a fun speed for them right now.
Eagle tree graph of a couple of passes.
That is great man!! glad you guys are having fun....
I'm dead in the water - my one and only pack got bloated and I'm trying to get it replaced.
The packs from HK have not arrived.
Hey, have you ever adjusted your Mystery speed controls for proper cut off with those 2200 packs ? http://www.suppomodel.com/ESC/escmenu.html
poobs
08-29-2010, 05:04 PM
My kid had a great time today. I packed the two boats and a tool box with jusy about everything we would need for the boats and drove a to a really nice pond that I'd seen.
We found a concrete structure on the shore and used it a s a base and launching point.
my Cracker box has the stock prop and Ebay Mystery outrunner. With two lipos it was plenty fast for him. After the 2nd pack we tried a 3S and shure enough he managed to flip it but the tape kept the expensive bits fairly dry.
There was a small gator in the water that kept peering out to see what the racket was.
adamb
08-29-2010, 06:10 PM
What motors do you run in these? I have a 20t brushed r/c car motor in mine but would like a bit more power and brushless efficiency.
adam, go back to the first link, I updated the motor source info on ebay since the old link was outdated.
Poobs, glad you are having fun with yours and your kid. I was going to go running today, but it was 95 degrees and humid today. Going to be a few days before I brave the heat after working in it all day.
I haven't tried 3s since I submarined it on launch. Charlie's is running much better since I adjusted the trim tabs back down. Doesn't do wheelies anymore.
Brian
poobs
08-29-2010, 09:27 PM
I used the motor that befu describes elsewhere in this thread.
I really like them.
What size prop are you using with the 20T ?
poobs
08-29-2010, 09:39 PM
My 3S packs are 25C and rather heavy. The crackerbox still seems to go airborne at full power.
There was a slight breeze and chop. I tried it down wind and it still felt like it would leave the water.
The same boat with nicads is fast but does not seem to leap out of the water as much.
I also ran the weird looking little boat in the pic very briefly with a 3S pack.
It was faster than the cracker box but it takes most of the pond for it to turn so I brought it back to shore...
poobs
08-29-2010, 09:42 PM
Thanks Befu
My 3S packs are 25C and rather heavy. The crackerbox still seems to go airborne at full power.
There was a slight breeze and chop. I tried it down wind and it still felt like it would leave the water.
The same boat with nicads is fast but does not seem to leap out of the water as much.
I also ran the weird looking little boat in the pic very briefly with a 3S pack.
It was faster than the cracker box but it takes most of the pond for it to turn so I brought it back to shore...
adamb
08-30-2010, 06:21 PM
Thank you!
poobs
09-19-2010, 07:54 PM
I ran the Cracker box boat again today with my kid and two of his little friends. Everything went well until I put in a 3 Cell Li-Po pack.
It seems that the sub surface drive lifts the rear out of the water and when it comes down again it walks the back of the boat to the side and that's when it flips.
We wanted to run two boats today but I only have one TX and two receivers on the same frequency. Still, the other blue and yellow boat will take the cracker box but the Cracker box will take it on turns.
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