AM Mean Machine Nitro to FE conversion

[rcflyer55]

I am starting a new thread because I did not want to hijack another thread on the Mean Machine. There a few on here that I have read and that have helped me decide to build one. I am a newbie with FE so if there is something that looks wrong point it out, hopefully I will be able to correct it on my boat, but at least it will save someone else from making the same mistake. I've asked a lot of questions from some of the members on here and received great feedback from them. Some things I am just trying to use what I think is common sense when building.




Most of the parts used were from the advice of "ReddyWatts" thread found here:
http://forums.offshoreelectrics.com/...read.php?t=751
and from the advice of "fluid". Without their help this project would have never even been started.


The first pics are of the boat as it comes. I have already pulled the
.18 and all the hardware and electronics. This left me with a hull with holes, a radio box and engine mount structure all made of fiberglass and attached to the hull.




Most of the equipment used was bought from Steve at OSE:

Feigao 10XL & ham-jack-540XL cooling jacket
M445 sharpenrd, balanced, and polished (by egneg)
Hydra 120 ESC
speedmaster hardware
4s2p Thunder Power Extreme V1 4500mA LiPos ***Replaced with 4s2p TP Extreme V2 5000's***
Hitec Fm Aggressor Srx Radio
As stated earlier ReddyWatts' thread gives a full list of the hardware.

*****Disclaimer***** The total $$ amount for my build is quite a bit more then Reddy's quote, topping 1G,
but I did buy Four 2s 4500mA Lipos, the more expensive radio, and the CC Hydra 120.

[RMZDADDY]

You should have a great time with that hull, they perform really well.
I'd never get rid of mine. Good luck with the new build!

[rcflyer55]

1st day working on the hull

I removed the radio box which was not too hard because it was not glued in too well. The engine pod was a bear to get out. I found a spot where it had a slight gap between the hull and the pod. I used a 6" steel ruler to slide in and started to pry it up. Next I used a combination of a Chinese saw and the ruler being very careful not to cut into the hull, which is not too thick. I also did not want to crack the paint on the bottom of the hull.

Next I filled the holes I would not be using on the transom with hardwood dowels and epoxy. I sanded the plywood transom and the inside hull to make everything smooth.

I measured to find the center of the hull and marked for the stuffing box(the hole that was there was a little off). I did the same to the hull on the inside for the motor mount and the transom for the strut.

I installed the strut first then the stuffing box. First I bent the 3/16" brass tubing, which was much easier then I thought it would be. I just took my time and went slowly so I did not kink it. When I was satisfied with the flex shaft running smoothly in the stuffing box I sanded the brass tubing where I was going to apply glue to give it some "tooth" as well as the hull. Then I clean everything with alcohol. I used masking tape to seal the bottom of the hull where the stuffing box would exit to keep it smooth. I used Devcon 2 ton 30 Minute epoxy mixed with ground fiberglass to install the stuffing box.

I cut the flex cable to the correct length, I bought an assembled one, with a dremel and a cut-off wheel. I smoothed the cut and cleaned it with acetone. Then I tinned around 1/2"-3/4" with silver solder. I ran into a small problem here. I could not get the flex shaft to go back through the stuffing box. It kept getting stuck unless I forced it in. So I re-heated the solder added more flux and made it flow more smoothly. The shaft seemed to suck in the solder this time. After this the flex shaft was easier to slide into the stuffing box.
That's all I got done today.

[rcflyer55]

I have a question about the strut on the brass insert piece(don't know the name of the part) should the shoulder be exposed or inserted in the strut? Because it fits inside. I was going to leave it out.

Please see attached pic

[Rex R]

a few things came to mind after looking at your pics...starting w/ stuff tube coupler alignment, from the pic it would appear that the motor could stand a tad bit more angle; you'll be wanting some bracing under the forward end of the motor; the strut bushing gets inserted flush w/ the back of the strut(otherwise the shaft would be flopping all around); I would suggest a piece of heat shrink from the stuffing tube to about 1/2 way up the nose of the strut(to keep the water out) hth
rex

[rcflyer55]

Rex thanks for the input. I see from the pics what you are talking about. The pic was taken before the final adjustment, and with a spare piece of flex shaft for mock-up. The actual shaft does slide right into the coupler now, you have a good set of eyes catching that. What type of bracing do you suggest? Perhaps you have a pic to show me what you mean.

The strut is only temporarily mounted at this point and I will use heat shrink tubing like you said.

Thanks for the info on the bushing, I will get it right during final assembly.

[Rex R]

did wonder if that was only a 'mock-up' mount pic(since I didn't see any epoxy). anyway...I used a piece of basswood for my mm(offhand I can't recall which size pipe I used as a sanding 'block'( it was either 1.25" pvc or more likely 1.5" pvc, with a piece of self stick 80 grit sandpaper)).
edit
pic shows how I did it. wood was shaped to matc the water jacket.

[Steven Vaccaro]

I did this conversion and found that the tunnel floor is very thin. Use some carbon cloth to strengthen that area like the picture in Rex's hull.

[ReddyWatts]

I did not have any carbon fiber so i used some thin hobby plywood. brushed a water sealer on it before epoxying it to the hull.

It just realized that it is hard to see in my thread photo's, since I painted the inside bottom of the hull. I better add it to the details.

[TRUNKMUNKY]

I also did this conversion and wound up laying some glass re-in forcement in the tunnel, and used an adjustable motor mount from ose for my 9xl.I love this boat and it out performs most other hulls at twice the price .Go ahead and put some power to it.!!

[rcflyer55]

More building 2nd day

The tunnel of the hull is a little thin so I added some plywood to the motor mount area as suggested. I needed a little height for the motor to line up exactly with the flex cable so it worked out well.

As before I sanded the hull lightly, cleaned with alcohol and used 30 minute epoxy so the glue would have time to penetrate the wood. I also used a "woodpecker" tool to put tiny holes in the ply. After that was set I brushed a coat of thinned epoxy(with alcohol) on the wood and on the transom making sure some got into all the holes but not clogging them.

After everything was dry. I mounted the motor mount to the wood again sanding the wood cleaning it with alcohol and making holes with the woodpecker. I also gave the aluminum motor mount a sand and a cleaning.

I used 30 min epoxy mixed with ground fiberglass to add strength and thicken it. I laid down a layer of the epoxy and pushed the mount into it and made sure it oozed through the holes to be sure it was fully bonded with the hull. I positioned the motor until I could hold the prop shaft and slide the flex shaft into the coupler easily. Then I let it set up.

I did not mention this earlier but when I installed the coupler on the motor I marked where it should be on the motor shaft when installed on the motor mount and taped up the motor and ground a flat spot on the motor shaft so the set screw would not slide. I also used Blue loctite on the set screw. Both steps are very important to make sure it does not slip.

Now I permanently installed the strut. I used clear silicone around it and on the base of the screws to insure no water would enter the hull. I also added heat-shrink tubing to the stuffing box and up onto the strut for a water tight seal.

I installed the rudder assembly the same way and added a linkage boot installed with clear silicone. I also installed a bulkhead fitting for the water inlet, again using clear silicone to seal it. The outlet fitting was already in the boat as was the antenna mount.

The building part is almost complete. I have a LOT of soldering to do, my least favorite thing. I have the 5mm bullet connectors for the motor and ESC, and a lot of deans ultra's for the Lipos. The deans are only rated for 40A so I may just use the bullets on everything. I bought a serial connector already made but the wire is only 14 gauge and I want 12 gauge. SO if I have to make a new serial connector I might just go the 5mm bullet route because they are easier for me to solder and I THINK they can handle more amps. Does anyone know this to be true?? Although I also think that 12 gauge wire is oly good to 41 amps. I am not sure how many amps I will be pulling with 4s 4500mA Lipos.

There will be more pics posted later the camera batt died. If there are any pics you would like to request feel free. I tried to take a pic of the motor shaft with the flat ground on it but it was too fuzzy even with the macro setting.

[Rex R]

deans plugs are good to about 70amps, as is 14ga wire. 12ga wire can usually handle 90-100amps(about what 5.5 mm bullets can handle) hth
rex

[rcflyer55]

I'm misinformed and that works out great. I just spent a few hours soldering the bullets on the ESC and motor, and Deans on the ESC and 3 Lipos. I'm waiting for the fourth one it is back-ordered. Looks like I am in the home stretch. Just a little ESC programming and final assembly like the water cooling lines and I hope to have it ready for this weekend. Maybe I can squeeze in a few runs on Sat. before a family party I am dreading.

[rcflyer55]

Finishing touches

The project is complete. All soldering is done. I went with the Deans Ultra's because I had them on hand. The CG was checked and it is around 9 1/4-9 1/2 in. from the back. I cut 1/8-3/16 in pieces of fuel tubing and used them on all the water fitting connections to insure no tubing comes loose during a run. I also added a small piece of tubing on the flex shaft in case it was to come out of the coupler I wouldn't loose it and the prop.

I still have to tidy up a bit put wire ties on the loose wires and put some foam around the Rx and batt and put them in a balloon and find a place to mount the switch. Otherwise it's complete. I believe if I had built a FE before I could have finished this project in 1 good days work. It took me 3 days not counting the soldering which I am slow at. It was enjoyable and relaxing unlike some planes I have built.

I plan on running it tomorrow. Although I only have 3 packs, I'm still waiting on the 4th. I will have my Hyperion Emeter and a temp gauge. I don't really expect to get to full throttle. I really want to see how the hull handles and how it is riding. It is more a a break-in run for the motor, hardware and Lipos but I'll try to get some video if I can coax my wife to come to the lake.

[ReddyWatts]

Be sure and raise the bottom of the strut up 1/4 of an inch above the bottom of the hull to start with, then maybe to 3/16 for best performance. 1 to 2 degrees up on the back of the strut.