Delta Force Explorer 36 twin Rebuild

[mmars89]

Hello FE boaters,

I built this Explorer a couple years ago with almost no clue what I was doing. I figured it was time for a rebuild now that I have a tiny bit of a clue. The first version was a 12s beast with swordfish 240HV's and Leo 4082 1000kv motors (Later switched to TP 4060 1050kv). The power was great but it was a lot of weight for this hull and there were a few weak links with the original components I selected; The aluminum angled motor mounts would bend under the torque, causing flex shaft blow outs. And the low profile 110mm struts would bend towards each other with the rotation of the props, causing major crashes at speed. So my plan is to use the 12s electrical components in a new Mystic 114 I'm about to start building and turn the explorer into a 100mph bulletproof 6s setup.
3) props

Here is the latest version of the first build, I constantly tweaked this build as I made a lot of mistakes the first time. Personal best was 104mph with a nice set of Dasboata props. I have to give it to this thing, it took one hell of a beating and held it together. So many big crashes along the way.

https://www.youtube.com/watch?v=XEra5DuKj-o
https://www.youtube.com/watch?v=nxRVN7WQMuQ




THE REBUILD

New build will consist of;

SeaKing 180 V3 ESC's
Leopard 4074 2200kv motors
Running 6s. I have packs from 4000 - 6000 which should all fit nicely.
Reusing - TFL medium scale rudder and Power HD 15kg low profile servo w/ carbon mount.

Goal: Mid-budget, 100mph reliably and able to take a beating. I do this for fun, I do not compete.



Everything busted out


All sanded and prepped and all holes filled with carbon shavings and resin. Ready for new carbon inlay. I did a poor job on the inlay the first time, it functioned well but was ugly and heavy.


Adding carbon strips to inside corners of sponsons as the walls were very thin.


Strips cured


Transom inlay

[mmars89]

Inlay complete


Made jigs to drill holes for drives




Holes drilled


I machined a set of 110mm struts down to fit the short transom of the explorer. Here is a before and after.

[mmars89]

Machined motor mounts out of carbon plate, epoxied two pieces of 2mm plate together to make 4mm thick. I added the motor vent holes after this photo was taken.


Getting mounts lined up. Tacked in place with CA glue before final epoxy. Motors further back than previous build for better weight distribution. Also, I used 40x82 motors for this to ensure I have clearance to go up a size if need be.


First round of epoxy on motor mounts.

[mmars89]

Quick rattle can paint job. Not going for showroom finish on this one.

[mmars89]

Final epoxy on motor mounts



Fabricated a carbon bracket to hold aluminum tubes for rudder cables.


Drives mounted


Motors, servo stand and trays in for batteries and ESC's. I machined these trays out of 2mm carbon plate.

[mmars89]

Cap banks



Installing everything


Water pickups



Mounting tabs for two additional hatch bolts mid hull

[mmars89]

Nearly completed, missing weather strip


Ready to run


I made a water cooling bath integrated into the boat stand. I fill this with ice water and circulate before and after runs.


Short video of cooling system.
https://www.youtube.com/watch?v=qYwMKOFkLUU

Weighs in at 12lbs 6.4oz with all foam and 4000 packs (12lbs 14.4oz with 6000 packs). Previous build was around 17 pounds with 6000 packs... I think this build is still a touch over weight due to the previous carbon inlay, was difficult to remove all of the old material without sanding through. It most definitely would have been way easier and saved a ton of time to have just scrapped this hull and bought a new one, but I couldn't bring myself to throw it out, some sentimental value there I suppose.


Time to run!

[mmars89]

Some short clips. Sorry for the sub-par videos, I'm not much of a videographer.

85 mph run with CNC 4616DT props
https://www.youtube.com/watch?v=2TCOYAyJVTI

92 and 93 mph runs with Dasboata props
https://www.youtube.com/watch?v=HhGeBoR4mAw
https://www.youtube.com/watch?v=PT_cvn3_Te8

So far the triple digit mark eludes me. The math says this set-up should be higher RPM than the previous (12s with 1050kv motors vs. 6s with 2200kv motors). But obviously this set-up produces much less torque with the lower voltage and smaller cans. It can't maintain the RPM with the bigger props. New props are in order!

I will say though, very impressed with these components. I thought for sure I was going to be battling heat with the bigger props, but it does great. I make about 4 good pulls on a set of packs and the highest temperatures I have seen are around 110F on the ESC's, 100F on the motors and about 85F on caps and packs. Can run it like a drunk teenager with X442's on, which do around 80mph with no heat issues at all.

New props are here, will post results after I get out again.

Thanks!

[fweasel]

Nice work.

[Dirk Jan]

Very neat rebuilt, thanks for sharing

[mmars89]

Nice work.

Thank you, much appreciated.

Very neat rebuilt, thanks for sharing

Thank you and no problem. I learned most of these building tricks from this forum, thought I better share it.

[Bande1]

Do you have a data log? I bet you're voltage is sagging to under 3.4v pretty quick. that would be my guess as to why the math isnt adding up. Try to some SMC HV packs.

[mmars89]

Do you have a data log? I bet you're voltage is sagging to under 3.4v pretty quick. that would be my guess as to why the math isnt adding up. Try to some SMC HV packs.

I do not have any logs, the SeaKings are pretty basic and I didn't put any sort of power analysis components in this build to keep costs down. I agree with you 100 percent though. I'm actually in the process of ordering new packs today, I think that is my bottleneck. I have LVC set to 3.4v and it has never cut out during a run, but it has to be very close. Thanks for the suggestion, I have heard good things about those, I'm going to look into getting a couple. I know a lot of people question the Zeee packs, and I'm starting to be one of them. I would think those ESC's and motors would be pulling the extra current if it were available, like I said, I expected way more heat a lot sooner, gotta be starved for power.

Thanks!

[Bande1]

I do not have any logs, the SeaKings are pretty basic and I didn't put any sort of power analysis components in this build to keep costs down. I agree with you 100 percent though. I'm actually in the process of ordering new packs today, I think that is my bottleneck. I have LVC set to 3.4v and it has never cut out during a run, but it has to be very close. Thanks for the suggestion, I have heard good things about those, I'm going to look into getting a couple. I know a lot of people question the Zeee packs, and I'm starting to be one of them. I would think those ESC's and motors would be pulling the extra current if it were available, like I said, I expected way more heat a lot sooner, gotta be starved for power.

Thanks!

all these budget packs are good for around 15c. 20c pushing it. I know all my amazon specials behave the exact same as these Zeee in the video as well.

[mmars89]

all these budget packs are good for around 15c. 20c pushing it. I know all my amazon specials behave the exact same as these Zeee in the video as well.

Thanks for that, makes sense. I've found very similar information on the Zeee's. And good to know about the other amazon brands, nothing looked appealing that I could find on there.

I just ordered a set of these bad boys;

https://www.smc-racing.com/index.php...product_id=755

Gonna give them a try. I won't change anything else and post the results. Either gonna break 100mph or melt stuff, either way will be entertaining!

[Bande1]

ohh hell this is gonna be fun

[mmars89]

ohh hell this is gonna be fun

Lol absolutely! It's not fun unless there is a high risk of catastrophic failure!

[Bande1]

lol I hope you got 8mm

[mmars89]

lol I hope you got 8mm

Sure do, 8mm bullets on everything I have. Connectors should still be good after the ESC's explode, so that's a bonus lol

[mmars89]

Update.

I received a set of ABC 1816 props from Dasboata as well as a set of SMC SRD-V3 Speedrun 6S 5300mAh packs.

I tried the new packs with the ABC 1814(3) props which I have been running on this rig. That combo did not work well. These packs have some serious punch, waaaaaay more than the Zeee's. It didn't seem to like the 3 blade props, it was lifting the back end out of the water and skipping. Some tuning required here perhaps, maybe some more weight needed.. not sure yet. I decided to give the SMC packs a go with the new ABC 1816 2 blade props from Dasboata, before messing with any tuning. This combo worked quite well, had some skipping at first but learned to be more gradual on the throttle and once she plants and bites, she goes good.

It hit 102mph on two back to back passes. And this was with a serious mishap on both runs... I seemed to have made the water pick-ups a little too aggressive (see above posts for a photo of them). At these speeds, it blew the tubing off the pick up tubes both runs... the boat very quickly filled with water during the runs. Not good. So basically I was doing a tractor pull, the boat was getting heavier by the inch, with no cooling to boot lol. Got lucky that nothing was damaged.


I had the silicone tubing ty-wrapped onto the pick up's which are made out of 7/32" brass tubing with slight notching cut into them to act as barbs. I can't secure them much better than that, aside from using adhesive. I have decided I have to re-work the pick-ups. Going to downsize the tubing from 7/32" to 3/16" and cut less aggressive teardrops. Curious to see how much speed was lost from taking on all that water, plus will be less drag with smaller pick-ups. Stayed tuned...

https://www.youtube.com/watch?v=lKXCzI1vZgw
https://www.youtube.com/watch?v=rnq0hEY39Hw

[Bande1]

wow thats insanely fast!

a good way to flare tubing is with the harbor freight center punch set.

[mmars89]

wow thats insanely fast!

a good way to flare tubing is with the harbor freight center punch set.

She's got a little more in her I think! Those SMC packs are incredible.

I did think about flaring the pick-up tubes, I have punch sets and a brake line flare tool kit that would work. I think I just oversized them though. My thought process was maximizing flow for the best cooling possible obviously, but at those speeds the pressures are just too great from those big pick-up's, much more than needed. I'm thinking 3/16" tubing with much smaller teardrops will be the way to go. Less drag also. I am also toying with the idea of going with 6v pumps and 3/16" pickups with no teardrops for even less drag. With that, I would run an external receiver battery pack which would be beneficial to not pull power from one of the ESC's BEC. Furthermore, if I'm right about needing a bit more weight in the boat, this would help with that as well. The pump set-up does make sense to me for a boat like this, going from a stand still to flat out pull and back to a stand still.