'11 U-88 Degree Build up-CF nitro hull convert to FE, cosmetic & performfance mods

[nichismo]

Hey guys! Just decided to share my current project (or one of them I guess...) as I had recently started taking alot of pictures and had been making alot of progress for the first time since recieving the hull some time back last year. Ive actually got quite a bit of content and material to share and talk about right out the gate, so forgive me for its length, and thank you to anyone willing to take the time to read and critique, as this is basically my 2nd build of any kind... ever. haha

First I just want to provide a little background info on a few things. Given my small amount of experience thus far (however learning A TON in this time frame), in the amount of time I waited to get this hull after paying for it, some of my goals and desires had changed a little bit, and then this was slightly accentuated when I actually recieved it and discovered a few things im not necessarily too keen on. Being that I was still working on my T5 at the time and far from completion, I ended up shelving the build and subsequently lost interest in it for a while. Even recently after making alot of new progress that ive been very happy with, I still had been considering that I would sell the hull to invest in new projects ive become interested in.

So with that being said, and also stating that im very happy with where the hull sits now and ill most likely be keeping it, id like to touch on the cosmetic mods ive been doing/will do (VERY extensive with this hull, as the real boat was a rather unique design by Ron Jones Jr. for Billy Schumacher), and also performance mods as well (namely, the entire bottom side to me is very bizarre to me and not exactly what I would consider sound, to put it lightly.....), and lastly the necessary steps taken to convert the hull to electric. The last one I feel is extremely important and something I feel like most people here on OSE in general should absolutely need to understand if they are interested in FE scale hydros, as the task needs to be acknowledged and understood as to what it entails in performance and setup.

Since I have alot of pictures already to share and only 5 can be inserted in a single post, ill address each of the things I talked about respective to the photos. So to start, heres a few pictures of the real boat, a picture of the hull early on before any real work was done, and where the hull basically is now, and the components and hardware ill most likely be using, or at least testing with!

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[nichismo]

One thing I had confirmed upon recieving the hull, and was actually a concern for me beforehand as I was told by a few that this was the case, is how HEAVY these hulls are! I mean being carbon fiber and such, its incredibly robust and rigid, I mean certain areas even on the top deck that would normally bow and flex with slight pressure feel rock solid.... But that doesnt really matter to me as its obviously adding useless weight! So this frustrated me quite a bit, as it was so substantial that I felt discouraged. But after looking around a bit more and gaining some resolve, I decided to tackle the issue.

That being said though, when I recieved the hull, I was very impressed overall with the quality of the "fiberglass" work. Compared to a couple other epoxy hulls/parts ive gotten, this one was alot closer to being ready for primer and paint than the others. Not completely loaded with tiny pinholes and the seam was done very nicely, inside and out.

Obviously this will be a goal that will last the entirety of the project and its not necessarily hit or miss in terms of success, but im pretty happy at this point with what ive accomplished so far.... It started with the engine tub and the floor in it. The entire hull itself is rather thick and I know Steve adds some extra reinforcement on top of that in the engine well....and as if that werent enough, theres TWO sheets of 1/16" ply laminated into the hull. I thought there was just one, but theres actually 2, with one extending a little farther foward into the cockpit. I figured that, combined with the wood blocks that are in place underneath more and more layers of CF, were probably pretty heavy..... and boy was I right. After tearing out most of the floor, what you see in the picture is basically the floor from the "radio box" to where the turbine tray would start... and guess what? that alone weighed a whopping 20 oz!!! I couldnt believe it.... and now I had this huge gaping hole in the floor. I proceeded to grab some poster paper and trace the cutout onto it, and then I cut out a piece of wood with that paper as a template. Then I sort of cut a U-like shape from the wider top portion, which was to accomodate the belly pan/cockpit running down the underside. From there on was pretty simple, I just stacked some ply and sanding each side down to blend in with the hull, and mixed some west with 406 silica to fill in any gaps between the wood and hull. Since then I fiberglassed the inside, with 2 layers in the engine tub, and just epoxied the outside and started glazing and fairing over it. Its turning out great, and the hull is already so much lighter with all that material removed!

So with the original wood blocks gone that were intended for a typical CMB or .67 nitro engine to be mounted, along with the "radio box" wall in front of the cockpit removed, Ive already started converting the hull to FE. Ill get back to this in a moment, for the next post id like to touch on the cosmetic/aesthetic scale modifications ive done/started.

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[nichismo]

When I first recieved the hull from Steve, it was basically an all CF version of his T6 with a couple small changes. He had already started work on the drop sponsons for me, and he used some foam, ply, and epoxy mixed with graphite powder to extend the back rear shoes so I could cut and sand them down to look more like the real boat. I have always thought Steves T6 looks very well proportioned and mirrored of the real thing, apart from the underside of course. But in this case, if I wanted to be satisfied and invest in this hull to be the Schumacher team boat, then it was going to need ALOT of work...

To start, I felt like aside from the fantastic cockpit, the cowling needed to change. The shape and size were all correct, but the point in which the air scoop began and where the cockpit ends was far too large, and the air scoop itself was also far too high. So I cut and seperated the cockpit from the cowling, and then cut and trimmed off about a 0.25" or so around the bottom of the air scoop. Then I proceeded to remove alot of material from the front of the scoop as well, so it could be scootched foward and rebonded with the cockpit. However, actually rebonding the two ended up being rather difficult as there wasnt much surface area to work with and the air scoop bearing over the bond area also made it cumbersome.... So I shaped a piece of foam to act as a bridge for the epoxy. You can also probably tell from the pictures I posted of the real boat, that I am fond of the saltwater snorkel... So clearly I had to have one for the scale version! Steve provided me with this as well, but I could tell when I got it that it was modeled after the slightly longer, flat faced one that the Oberto would use so often. This was an easy fix, as I just cut the front to be at an angle parallel with the cowling, and then angled it axially also to accomodate the aerodynamics in turn. Looks far more like the full size snorkel now.

The pink/light purplish stuff on the port sponson, is foam with west and 407 filler over the top. Im still working on this modification, but im basically adding some height to the top of the deck in that area, as the downward sweep on that sponson on the real boat wasnt virtually nonexistent beforehand. The dropdown before seemed to just begin at the front of the sponson, and stayed level all the way to the back, whereas the real boat has a very pronounced "V" like shape to the angle of its drop. The port sponsons is much more apparent in this feature and its important to me that I get this part of the boat correct. I still need to add a little more height to the front tip of the sponson, and a little bit more to the middle, but i just got the 410 filler and I havnt tried it yet so ill use that this time as its supposed to be much easier to sand. in addition, ive noticed that as a result of the dropdown mod, the curvature of the deck starting from the back of the sponson to the transom has a very "sunken" like shape to it and its really distracting to me. So I have gone and skinned over that area with some balsa to fair down to the angle i wanted. Ive got it looking much better now, and I also used a few coats of west, in combination with some fairing fillers and graphite tow (tow not shown in pic yet) to strengthen it and blend it back into the hull

I wished I hadnt gone and epoxied the ram wing into place already. I didnt realize it at the time, but the ram wing included with the kit is massive! Looking at photos of the real hull, the wing is much smaller in comparison, and is a much more teardrop-like shape overall. Hopefully I can remove it cleanly, as I dont want to have to remove the carbon fiber rod underneath it.

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[nichismo]

So now ill get into some of the stuff I have been doing to accomodate the electric conversion.

I been feeling really good about the progress I have been making here, but I still got a huge amount of work to go even before testing. The sub hatch setup took me a while to plan out, or rather decide with how I was going to go about it. The last one I did for my last build gave me alot of trouble in all honesty. Its a simple concept but too me its very important, and a critical part of converting the hull from nitro to brushless. I see alot of guys whom have done FE builds in nitro hulls in the past, and for this aspect, they simply take a couple basswood sticks and glue them to the engine tub wall edges and call it good. They just throw a makeshift piece of lexan on it before hitting the water and then wonder why their ESC suddenly crapped out or their batteries dont stay warm, etc. At this point though, Im really happy with how my hatch came out.

Alot of people dont even consider a classification or designation with hulls in this sense with their builds, but with scale hydros in my opinion, its critical to the design from the start. I really wanted to have the lip all around be as flat and level as possible, and for the actual hatch to sit as tightly and flush as possible too. I ended up incorporating the sidewalls of the cockpit area into the lip to help achieve this, and overall it came out pretty well I think.

Also I made my own motor mount and ESC setup, pretty simple but I hope it should get the job done. Originally I had the idea of having the motor flat and parallel with the floor and running an S curve with the flex shaft, although that leads me again to wonder about the driveline and flex shaft setup. I know it may be against typical setups with scale hydros and perhaps against conventional wisdom, but I am thinking ill probably run a teflon liner inside the stuffing tube this time, as the idea of not having to constantly oil and grease the flex shaft really appeals to me. Ill be drilling out the slot and epoxying the motor mount and other component accomodations tonight, and then ill be sealing up all the wood.

I sanded out the inside walls of the cockpit to the best of my ability, as the inside seam had a huge gob of epoxy running all around and it actually probably gave me a good quarter inch or so of extra width up front once I removed it. The packs in the picture are 4s, 5500mah packs, and I have the same ones in 5s as well. I feel real good about where the COG is at this point, and theres plenty of room for even bigger capacity batteries, hopefully I wont have to add more than 10oz total of lead in the front sponsons before testing. Ive actually been really interested in vacuum forming a bit lately too, and ive nearly finished making my own little mini vacuum forming device, I just need to get some pegboard from somewhere and i can finish it Ill be making some of my parts with high impact Styrene, like perhaps the rear wing set and canard, and possibly the ram wing. Its nice because I can get the styrene easily from Tap plastics here in seattle, cut to any size in 1/16" and 1/8" thick, and they form splendidly. These should make the pieces really light, and theyll be extremely easy to prep and work with, all while saving some weight im sure

Recently I bought the HET motor in the picture off the marketplace on OSE, as it was a very very good deal that I couldnt pass up. This model motor is actually legal in some races here but not in this KV version as this is 1170 and they only allow the 840kv model. Since I have seen alot of guys running their 8th scales with the 1Y wind NEU (1250kv I believe) on 8s, I figured this 1170 would be just fine.I

more to come!

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[nichismo]

UPDATE: Post 1/2

Got enough content for an actual update now, yay ^_^

I also finished the reshaping of the port side non trip I discussed in the last post, im pretty happy with how it looks now, and overall the dropdown on the sponson from the front of the boat and all the way to the back looks alot more like the full size boat now. I just need to add the small sloped bulge at back of the sponson deck now. In addition, I did my best to sharpen the edges of the deck and sides of the non trip, as the real boat in general from all angles just seems to have crisp, streamlined surfaces and seams, and Steve adds alot of thickened epoxy to all these areas for strength, so ill be doing ALOT of sanding (and filling??) all around the hull to recreate that look. Aside from the dropdown in the sponsons themselves, this is one of the biggest things I like so much about the U-88/U-37, but as far as actual aesthetic modifications to the hull, im getting pretty close to wrapping it up.

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[nichismo]

UPDATE: Post 2/2

Elsewhere, im getting pretty close to finishing up most of the component mounting and internal accomodations. I decided to scrap that makeshift motor and ESC mount I fabbed up (or tried to) and just ordered a more standard 40mm sized motor mount from OSE. Should be here in a day or two at the most, and then after I get that glassed in, ill figure out how ill be mounting the ESC (most likely the same, with a plate positioned above the motor). Ive glassed the outer stuffing tube into position, epoxied the lot of it and subsequently faired over and cleaned up the surrounding areas too, as i needed to do this before I started on mounting anything else, im really pressed for room at this point. Thankfully its worked out alright so far though, as I have the servo mounted and in position, along with the other radio gear as I originally planned. Now I just need to secure the lipo packs in the cockpit (most likely with simple wrap around straps) and the electronics box will be pretty much finished!

Next im going to close up the inside of the engine well. Since removing so much of the original tub walls and floor has altered the overall structure of the hull, im a little concerned about the flex in the top deck. So im probably going to drill a couple holes in the bottom of the hull and run a dowel vertically through each to reinforce the top deck, epoxy them into place and then cut and fair afterwards. Perhaps ill use some 5/16" carbon rods or tubes. After this, ill close off the tub again with a little bit of pink foam for the sides of the e-box, and some G-10 the rest of the way. After I finish all this, ill setup the points for securing the cowling, setup the rudder pushrod assembly, and then finally create a system for mounting the dummy turbine and tray.

try to get more soon!

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[nichismo]

UPDATE POST 1/2:

hey guys, have an update for this build if anyone is still interested would love some feedback and constructive criticism!

Ive gotten the motor mount glassed into place and driveline setup nearly squared away, I just need to figure out exactly what kind of strut ill be using. Ive actually started contemplating where and how ill be "mounting" the ESC however. Originally I planned to work in some sort of plate that would bolt in overhead of the motor that I could run straps through to secure the ESC, but I was worried about the subsequent protrusion on the sub hatch and whether it would fit underneath the cowl. So you can see a chunk of the deck is missing in some of the pictures, I may just remove a portion of the radio box wall and create a side pocket, similar to where a fuel tank would be and just put the ESC in there.... not sure yet entirely though.

I also got alot more cosmetic work done on the hull, and im really liking the way the hull is starting to shape up. I mentioned earlier in the thread that one of the things I really like about the aesthetics of this hull is the sharper, crisp lines and streamlined details, and its important to me to try and mimic this the best I can. Being an epoxy hull, obviously most of the edges are rather rounded, and even with plenty of sanding, they will only get so sharp. One area in particular thats been bugging me is the inside walls of the sponsons, and basically the entire picklefork area in general looked nothing like the real boat. So ive removed the ram wing entirely and ill be making my own thats more accurate, just havn't decided how exactly ill be doing that. After I did this, I cut out a couple pieces of 1/32" ply and shaped it to cover the inside wall of each sponson, plus extend a small portion foward of where the curve of each sponsons tip begins, so that there was basically a gap there. I then subsequently glued the plywood pieces into place, and filled in the remaining gaps and edges with thickened epoxy, and sanded it all to blend in and sharpen the deck seams. Im pretty happy with how it looks as a result and im thinking by the time the boats ready for primer and paint, its going to be a big addition towards the scale look of the boat. If you compare previous shots of the hull to the ones in this post, you can see what I mean.

I dont think ill be doing any more major cosmetic changes to the hull at this point, as I feel anything else would be overzealous or simply not worth replicating. I still need to do the rest of the transom work, extend the rear end of the cowling back a bit, and figure out how ill be finishing the rest of the engine tub and the rear tray setup, and im confident that once ive figured that stuff out along with whatever other smaller finishwork I have to do, that the hull will be adequate in serving as the U-88 :) hopefully! Its a little odd, as overall this boat is not really drastically different from other typical unlimiteds on the circuit in the past decad.... and aside from the drop sponsons, there isn't many glaring aspects of its design that differentiate it. However, despite that, its general form and essence still seem to embody a very different look overall. So now ill be moving on to the changes/additions I have been wanting to do to the bottom of the boat, namely adding some depth to the rear shoes and non trips, and the rearward sponson pads as I think this hull will need it badly.

[nichismo]

UPDATE POST 2/2:

Im also going to be trying a few other somewhat unconventional techniques for this build, sort of like an experiment in one aspect, but hopefully still successful enough to use long term.

Rather than glassing in an 11/32" sized brass tube for the shaft log, I instead glassed in a 3/8" tube, in order to run an 11/32" tube for my actual stuffing tube. This is because I wanted to give running teflon liner a try despite using a .250 sized cable, I havn't been keen on greasing the shaft in my T5. As a result, Ill be applying a few more items that I hope will be key in accomodating the teflon setup to work successfully:

- I tried to make the angle of the driveline as subtle as possible
- I will only be using teflon for perhaps 2/3 - 3/4 of the actual length of the entire shaft, specifically in the bent areas of the stuffing tube, where friction and rubbing would normally be taking place and then the rest of the shaft will have breathing room to spin freely. Hopefully, this will in theory keep the liner from getting worn out faster than it would if it were occupying nearly all of the space inside the stuffing tube.
- Rather than a more conventional collet or coupler between the motor shaft and flex cable, ill be experimenting with a square ended cable setup there. This way, the shaft will still be moving "freely" rather than being fixated with the motor and not necessarily generating as much torque when its being yanked as RPMs rise.

Ill still liberally grease the entire thing before I set it up for good, but I think ill most likely be CA'ing the teflon on each side as opposed to having it glued to the inside of the brass tubing. Not entirely sure about this yet however, still need to give it some thought and research. Im excitied though to see how it works out!! Lets just hope it doesnt backfire...

heres some more shots of the boat, the last 2 are actually from a week or two ago, basically after I finished shaping the deck to get the dropdown angle on the sponson correct.

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[jhl1963]

Cool project - any update?

[nichismo]

Wow, I completely forgot I had made this thread. Its certainly time for an update!

Ive done even more modifications to the hull since the last post here, and despite really feeling overwhelmed at one point for getting quite a bit overzealous with my changes to the hull, ive now started sanding the entire hull with 220 grit in prep for my first coat of primer. However, ill be mainly using this as a sealing coat of sorts, to get the hull all one color and protect some of the filler ive applied. Ive got some Klass Kote epoxy primer that ill be brushing on in an effort to reduce wasting it, and also to help fill some of the smaller imperfections and contour the surfaces of the hull. I expect to block sand majority of this coat off, obviously. After this ill take the boat for a test run to see how it performs so that I can make any more changes to the ride surfaces if necessary before I begin the actual finishing work and prep for paint.

I wish I would have taken more pictures of certain key points during the mods, but I didnt so I want to start by attempting to list the changes ive made since last posting here.

probably the largest change is that I removed the entire cockpit section and moved it backward about 1.5 inches. I had noticed the cockpit on this particular hull was too far forward even before I recieved my hull just through pictures I had seen, however I didn't feel like changing it because I felt that it enabled me to place the batteries farther forward and thus, less weight would need to be added in balancing. But obviously I changed my mind and im amazed at the overall aesthetic change since. In addition, this was the perfect time for me to replace the carbon fiber tube running between the sponsons for the ram wing, so I epoxied this into place with a steel 4-40 rod inside of it.

Ive made extensive additions to the entire underside of the hull. Ive added about 1/8" to both the sponson ride pads and the rear shoes. The ride pads on the sponson were also widened and the angle of attack changed, now they are much more profound in definition and very sharp :)

Accurately reproducing the transom of the U-88/U-37 has been very difficult, alot more than I at least anticipated, and thats even with a certain noteworthy characteristic on the real boat being omitted. I had trouble deciding if I really wanted to leave it out, and now im glad I did as that would have been just a mess of work and stress! At this point, ive added a little bit of balsa thats been glassed over with 3.7oz cloth to get the correct shapes. Im still concerned about the corners though, theres really just alot of sharp edges on this boat!

But thats certainly one of the reasons I like the full sze hull so much, it just has such a cool, streamlined and cutting edge design in its appearence. The mods I did to the deck and inside of the sponsons walls are almost complete, and im really happy with how they turned out considering the amount of work I had to put into them. The shape of the sponson tips and getting the top edges of the inside walls sharp like they are now has really improved the look of the boat form the front. The drop down on the port sponson is at an angle thats much similar to the real boat, and im happy I went through with this change.

I only have a few crappy pics at the moment so ill post them, but im going to get more uploaded ASAP that detail the work ive discussed above. Thanks!