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07 Nov 2006
 A friend of mine bought a TRAXXAS Nitro Vee and
we decided to get some experience with this model. And we had lots of
problems...
The fun part...
This boat returned from the dead. The beginning was terrible. Lack
of experience and some basic mistakes on the design of the boat, almost made us cry and
scream...
What we know after 24 (yes, that's twenty four) hours of running time
Now, after all the run time accumulated by the .12 engine we can take some
conclusions about all the modifications made to the boat.
| 1. |
Good cooling helped this engine survive 24 hours of
run time. The first piston and liner only lasted about 1 hour of running at higher than
adequate temperature. After a run, a drop of water would evaporate immediately. Now we can
touch the head after a 20 minute run.
The cooling capacity just wasn't enough with the very thin tubing installed on the kit.
Changing this is an absolute necessity.
See Tips. |
| 2. |
The Octura propellers are much more efficient than
the plastic prop included on the kit. Whether you have the .12 or the .15 engine you'll
get more performance from it with an X440 or X442 prop. However, higher the speed, bigger
the problems. The boat can start to show some handling problems when turning to one side.
Spins can start to happen.
See the outdrive effect. |
| 3. |
The exhaust tubing will burn close to the metal
manifold. It collapses a little bit and the gas temperature is very high on that location.
There is no solution for this other than changing the tube with a more resistant one. We
changed it for high temp silicone tubing for tuned pipes. It lasts a lot longer and it
doesn't collapse as much as the original. |
| 4. |
The fuel tank lid will crack. Have at least one
replacement at hand. Nothing is more frustrating than returning home just because that
little insignificant part doesn't work anymore. The price is low and you'll be prepared. |
| 5. |
Some cracks will start to appear below the muffler,
caused by the high temperature. Just try to keep the hull in one piece. A layer of epoxy
below the muffler will avoid severe cracking. Or you can just put a tuned pipe on the boat
and see it fly... Chances are that you can cause cracks somewhere else on the hull :-) |
| 6. |
The little engine is resilient. It only shows some
erosion of the chrome layer on the liner close to the exhaust port. This is perfectly
natural for this run time. This running time would be equivalent to 144*10 minute flights
on an airplane engine (if it doesn't fall from the sky long before...) with the rpm on the
10.000-13.000 range, usually at half throttle most of the time and only the good ones show
some health with this kind of use. It's really a pretty good engine. |
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After some modifications, the boat became an incredible speed
demon. We are running it on the limits. The steerable outdrive and the speed will make it
spin if we don't take care. But in the end, we can get 20 minutes of running at full
throttle and lots of adrenaline. What is amazing with this boat is the fact that it was a
slow and sluggish boat with the standard propeller. An OCTURA X440 turned it into a fast
and fun boat. No more launching to reach plane. It will plane with no help in just a
couple of meters. However, the outdrive effect is amplified with the higher thrust we get
from the prop.
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On a monohull
which banks when turning, a steerable outdrive will point downwards and lift the back of
the boat, causing it to spin out.
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And now the problems...
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Day 1 |
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The engine wouldn't rev up. The problem was related
with the waterproofing we did. It was so effective that the engine couldn't breathe. Some
isolation was removed and it started to accelerate OK. |
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Day 2 |
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The engine would stop dry for no apparent reason.The
muffler was loose. The screws that hold the muffler are to short, about 3mm. They were
switched and larger screws now hold the muffler. The engine stopped because the pressure
on the tank fell to a level in which the carb couldn't get any fuel. |
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Then the pull starter recoil got loose.
We put it in place but know we have to be extra careful because the cord is a little bit
shorter. |
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Day 3 |
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The pressure tap got loose. |
Here we started to understand that we have to check all
the screws before going to the water.
 This is the boat at full speed with the original propeller. Below is a photo of the
boat with the OCTURA and you see the difference... |
The first 3 days
As you can see our first three days at the lake were not very
rewarding. We had all sorts of problems because of inexperience and mechanical failures.
The boat seems to be almost tuned, but we will only know when everything is checked and
rechecked.
This boat made me think that this kind of hobby can be very disappointing.
And it was...
The reason for these problems was very simple. The cooling system
had very thin tubing, and on the first day we inflicted damage to the piston and liner
equivalent to a complete year of use. The engine stopped over and over due to overheating.
A complete remake of the cooling system was enough for longer and cooler runs.
Can you tell the difference
looking at the pictures below? Do you see what a good propeller can do?
|
A new piston and liner revealed what we already knew. They were
ruined!
Now the boat is fun ! It gets on plane easily and the speed is much higher than we ever
saw (even on the first day).
However the original propeller cavitates enough to overheat the
engine when trying to get on plane. An Octura X440 cured this.
A TRAXXAS .15 is waiting to be installed. When the .12 dies.
The marketing guys (I've been one of them for a couple of years, and I knew
how to turn serious shortcomings into thundering victories) never cease to amaze me: TRAXXAS
says that they put the best propeller on the boat...(look at the pictures and
judge for yourself) I don't think so. The original propeller is really bad, and makes a
fun boat become a nightmare. The expense that my friend had with the boat was enough to
buy a first class hull and engine. If only the cooling system and original propeller were
better, we would never had the idea that the boat is worthless. For a couple of dollars
more TRAXXAS is ruining their own reputation.
When I read the reviews about the boat I wonder if we are special
(accident prone) or if the reviews are biased to please the maker of the boat. The last review I saw had only good points and no inconvenients (I
wonder how they did it). The rec.rc.models.water guys have very different
opinions.
Tips
 Substitute the cooling system tubing
 This is
probably the most serious shortcoming of this boat. If you run it for some time, with a
leaner mixture than the ideal is almost sure that the engine will overheat. If it does,
your piston and liner will be ruined pretty quick. In our case it just took a couple of
hours. After that the engine would not rev up and the carb settings were impossible to
adjust.
The plastic pickup tube was switched for a brass tube (4mm inner diameter) mounted on the
same plastic base. Just cut the old plastic pickup and drill a hole a little bigger than
4mm on the plastic base. Insert the 4mm brass tube with a 45º cut on the lower extremity.
Change the tubing for a larger diameter silicone tube and you're done.
There was another modification we made on this - The hot water now leaves on the side of
the boat instead of traveling to the rear of the boat. Less tube, less friction = more
water traveling on the system = more cooling capacity. Now the water is ejected about 40
cm to the left side of the boat when running at full speed. Even with the RTS system
running some water passes through the head.
Change the propeller
If you want good performance, you need to change the original
propeller. This boat had a molded propeller impossible to remove from the shaft. 2 new
shafts were made on a lathe - one for 1/8" propellers and other for 3/16"
propellers. Because we use OCTURAS above X435 we just use the bigger one. I understand
that OCTURA makes an adapter for this boat - PN
OCGCSS
(I suspect that someone at OCTURA tried the boat and found the same problems we did).
Change the turning fin (if you want that little extra
speed)
We got rid of the turning fin. It makes the boat unstable when
turning right. It's not placed correctly (perpendicular to the V and aligned with the hull
strakes) and causes the curve radius to be too big. When we force it the boat spins and
leaves plane.
Additionally because of incorrect position causes drag making the boat turn right. We have
to adjust radio trim to the left and instead of having a perfectly aligned thrust line,
we have opposing forces instead of forward thrust. A new Prestwich Model turn fin
will be installed correctly (perpendicular to the V of the hull).
Review
| I like |
| |
The boat comes assembled and almost ready to run. This version is
the basic version without radio, the complete version comes with a TRAXXAS 2 channel AM
system, and that's the only difference between the two versions. Excellent decals. |
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The total time spent for finishing was around 3 hours. |
| |
The appearance of the boat and all the details reveal a well thought boat. The
shaft is lubricated with oil from the exhaust, the motor mount and all the interior of the
boat has small details that really pleased me.
The best feature is the RTS (Return to Shore System).If you get stuck in the middle
of the lake, you just switch it on and calmly return to shore. All the nitro boats have
this disease sometimes... |
| What I didn't like after
running it... |
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The propeller is bad. It cavitates too
much and the engine can easily take a larger one which will stop cavitation due to a much
higher efficiency. |
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The cooling system has very thin tubing that will surely cause
overheating, with the results described earlier on this page (piston and liner completely
ruined) |
| In conclusion |
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As you can see, if you change this couple of things before running
the boat, all the problems that we had will never happen. If it is your first boat, is
almost certain that you have the same problems before experience helps. It can be too
late, so please beware. |
Present config.
| Motor |
Traxxas .12 |
| Fuel |
10% nitro, 12 % synthetic oil, 4% castor |
| Propeller |
OCTURA X440 (surface piercing) |
| Receiver |
Multiplex UNI 9 |
| Throttle |
Multiplex MS 12 |
| Steering |
Multiplex MS 11 |
| Radio pack |
Dry Cells with voltage regulator
(Home made) |
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The MULTIPLEX MS11 and MS12 servos Size HxLxW [mm] 36x40x19
Weight 44 g
Torque [Ncm] 26
Rotation Speed to 40° [sec] 0,21
MS11 is waterproof and MS12 is not. If the servo (MS12) starts to
behave strangely, is almost sure that it has water inside. Keep an hair dryer at hand...
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