How to get into FE tunnel the right way.

[Bill Britton]

It may seem at first that this post should be in the FE forum but after I thought about it, I realized that it really belongs here in the O/B forum. Tunnel guys thinking about trying FE will find this info here easier than looking through the general FE forum threads.

Choosing motors and esc is not as easy as it would appear. There are volt/amperage considerations that must be thought out. Esc's have multiple parameters that can effect performance, etc. My recommendation to any tunnel guy thinking about giving FE a try is to build a spec boat first. I'll say it again, just so those who tend to breeze through a topic can see it.

Build a P-Spec boat first.

This does two things;

1, Gives you the familiarity you need to put together a combination that works and is almost bulletproof because the parts have been matched by those who are already in the know.

2, Keeps you from going straight to the 'hot' setups that will almost certainly 'smoke' if you try to build one on your first attempt.

You can blow a lot of money very quickly by jumping right into the bigger FE classes by not knowing what you are doing. Call it discipline or whatever. The spec setup will ensure that you end up with a boat that will be competitive right out of the box with little risk that you will ruin parts and call it a wasted venture. It also exposes you to the elements that need to be considered when building an FE boat, basically matching the right motor/esc/batteries together.

After my first P-Spec build, I realized that the was no mystery to FE, and that It really is an easy build. Although I do have a lot of nitro stuff in my inventory, I do not see myself running nitro for a long time, if ever at all. FE is that much easier to put together, will never blow a plug or throw a rod. Power is equal or greater than nitro. The cleanup afterwards is easy and requires nothing more than a few shots of WD-40 or Corrosion X in the motor.

I am far from an expert in this field and will open the thread to those who know much more than I. But I can almost guarantee that they will agree with the concept of starting with spec. In the end it will save you tons of grief by knowing what motor ratings can go with what esc's, etc.

Maybe Mic will chime in here and give his opinion of starting out with spec and the result of his first FE boat.

With that, lets hear from other tunnel guys who have FE knowledge to share.

 

[RonShaw]

Bill,

This is a great idea. I certainly do not know the first thing about FE Tunnels so, "I am all ears on this one." Thanks for getting this thread started......

 

[HTV Boats]

By no means do Bill and I have all the answers here, we are trying to give our experiences and results and hopefully save you a couple mistakes. FE performance can be attained different ways with motor KV, Battery voltage and propellor load. It is very easy to go up in smoke not having all 3 in harmony. For sake of argument lets say I was running an m445 prop and not heating batteries and controller over 120 degrees. Just going to an M545 a minor pitch change shot me up close to 160 degrees. A M447 would probably just gone up in smoke. This was with a 2200KV motor and 4S (14.8v). Just changing the motor down to 2000KV or 1800KV might allow the stiffer props but my RPMs would go down. No load rpm on 2000kv and 4s is 14.8 X 2000 = 29600 rpm and under load it might drop to 26000. A 2200kv would yield 32500 no load and a similar 3000-4000rpm loss in the prop load. 1800KV X 4S yields a no load 26400rpm. Somewhere in the mix combined with hull efficieny you will find the sweet spot.

Next you have amperage and its result is heat. One set up may draw x amps and the prop change over the cliff can close to double amps quickly. h34r: smoke $$$ h34r: You can up the amp rating with high buck controllers but will then find smoke in the next fuse, the motor overheats. It is a balancing act but not as difficult as it sounds if you stay in known parameters.

This is why we recomend the P spec/limited option to start. It has been done with proven components. You still can over prop but staying within what others have worked out will give you a nice running hull. What a lot of boaters have done is take the combo and put it on a boat they have laying around that is laying around because it wasn't cometative and expect big results. Crap in = crap out. I tried the P-spec on a heavier .45 hull of mine and with an GR 42X55 it pushed it into the low 40's. Same setup on a Lynx,Vision21 or Shaman and you can up to a 42X66 or M445 and see low 50's with acceleration you wont believe. Go too light like a VS-1 and you will have a rocket ship that few will be able to land. A P-spec will run all over good stocker OS's and will not give you the speed of a mod 21 but it may easily out punch it.

This brings us to well just add HP like we all think and go to a Q (22.2V) Been there and Q in a tunnel is doable but the batteries are bigger and rigging in some boats your cramped for space. The extra weight has disadvantages also. Motor working KV ranges go down in the 1100-1600KV range. 1600X22.2 = 35520 no load rpm. Another set of sweet spots and parameters to learn. One option may be just 5S or 18.5v and again its own range. I have only dabbled with both and there is more power availiable but maybe beyond some tunnel capabilities. In open class the .45's have dominated the win column with handling and resonable speed, The heavier .67's and .80's are faster in a straight line but .45's still seem to be the dominant winner over time.

That brings me back to a full "P" setup with larger watt 1800-2200kv motors. Someone correct me but I believe the Aquacraft 2030kv is around 1000-1200mw. One watt = 1000w = 1.36hp So with a very efficient NUE 1515 2200kv rated at 2500w and a less efficient Leopard 40X82 rated at 3500w at ahlf the price $200-$100 respectively "P" is worth looking into before you go off the deep end in "Q". Yes a "Q" will be faster but we feel it might be back to a .45 still beating .67. If you go the "q" route and stay disiplined in props it would be better but it is just too easy to jump speeds beyond hull capabilties. Another reason we are going to focus on "P" is then we share batteries with our spec boats and conserve costs getting started. If you have the funds and want to go big have at it. Another reason in actual testing my hull (HTV) ran 54mph on the radar and was too just too heavy. This is with the 2200kv Leopard 4082 ($110) a Swordfish 200a ESC ($100) and a M445 prop. The same powertrain on a Shaman walked all over me low and top end but was 2 lbs lighter. In rough water I would prevail and thats racing choices. These are just results with limited testing so far. I believe a full "P" is capable of 60+ mph and sub 13 second lap times. As we get into FE deeper and start using data loggers we will know exact rpm and amp draws on props and boats. Just time and money but the performance potential is addicting.

Get the basics with a P-spec Tunnel and expand from there. Many out there with more knowledge than Bill or myself will be glad to help. If I have any blatant inaccuracies here please correct me as I am learning. If you want info start reading threads on OffshoreElectics forum. Go into the charger and battery talk section and read old threads till you feel comfortable with Lipo knowledge. Lots to learn there. Their ratio of sport boaters to racers is much different than IW. We are more race oriented but they have the experience we can build on.

Confussed yep but once you start you will be "assimilated" Different tunning, no fuel mess and cost and no more glow plugs. Go vvvrrrooommm vvvrrrooomm if you need noise. There are a couple other threads here and the FE section on tunnels you should read and ask questions. Lohring and some west coast guys are doing simalar things with different but valuable approches. Many combos here to find the balance and sweet spot, back to what makes racing fun, outthinking, outengineering or just outdriving the competition.

Mic

 

[topfuel443]

Great thread Bill... I was just contemplating an Open tunnel FE build to give my 40 boat a break... I will be watching this one. How about some specifics on the boats you have built?

~ James

 

[RonShaw]

Bill/Mic,

This is all great information. This will help many of us that are just getting started. I guess one of the reasons I was thinking Q is two fold. This area is still a new area for tests and I already have a couple of 40 hulls to use for experimenting. I was also thinking a P-Special or P so after reading your thoughts above, that would be a great place to start as well. Would definitely be cheaper as a lot of the leg work had been completed. I want to thank both of you as this information will not only help me but many others that I am sure will find this thread interesting and informative. Maybe some of the other FE Tunnel guys will chime in as well................

 

[Bill Britton]

Great thread Bill... I was just contemplating an Open tunnel FE build to give my 40 boat a break... I will be watching this one. How about some specifics on the boats you have built?

~ James

Gabe

***********************************************************************************

P-Spec;

Lynx hull

Aquacraft 2030 motor $69

Aquacraft 7011 Esc $89

OSE Cooling Jacket $18

Turnigy 4S 40c 5000mah batteries $50

OS Lower unit conversion kit $35

Turnigy batteries are here;

http://www.hobbyking...idProduct=14985

Motor, Esc, and cooling jacket can be had as a kit here for $162;

http://www.offshoree...d=dh-aqcom-2030

OS Lower unit conversion kit is here. (Hyperformance also makes a kit for the lawless as well);

http://hyperprod.biz...ersion_kit.html

***********************************************************************************

***********************************************************************************

P-Tunnel;

Shaman hull

Leopard 4082 (2200kv) Motor $100 (Although a Leopard 4074 2200kv is probably just as good if not a better choice)

Swordfish 200 Esc $100

Cooling Jacket $16

Hyperion 4S 45C 5000mah Batteries $125 (you can also use the same Turnigy batteries used in the P-Spec)

OS Lower unit conversion kit $35

Leopard motor is here;

http://www.offshoree...eo-4082&cat=148

Swordfish 200 Esc here;

http://www.offshoree...hef-sword-200lv

Leopard cooling jacket is here;

http://www.offshoree...leo-4068-jacket

***********************************************************************************

Here are the threads with my P-Spec and full P.

P-Spec: http://www.intlwater...showtopic=44936

Full P: http://www.intlwater...showtopic=47010

/B

 

[ggeiselman]

How long is the shaman? I might start a p tunnel, but want to use a hull I already have.

 

[HTV Boats]

kv_voltage1.pdf

Maybe this will give you a better understanding of KV - voltage and unloaded rpm potential. Just cause you can turn 40000rpm does not mean the prop will be efficint with the same percentage of slip at higher speeds. At some point the blade speed is going to blow up in cavitation.

Another thing to consider is making power as your volts go up the amperage draw goes down so a "Q" does not need to draw as many amps to accomplish the same performace. When you get to 8S and 10S setups your controllers don't handle near as much amp loads. But weight and larger battery capacity come into play besides just cost. What we are trying to do is within 6000mah of battery to run the laps. As you prop down your lap times go up. So that big prop you can turn in a straightaway may consume your power in 4 laps. Balance of the total setup. 10000ma batteries are the max allowed in FE heat racing but over 6000 might be impractical in just size and weight in 29-36 inch tunnel. On a "P" spec you use 3500-4000 ma in a heat. Full "P" we don't know exact draw yet but may need conservative props to finish. "Q" again more weight to get more power. 2 and 4 engine dragsters never panned out.

Mic

 

[TUNLBOTR]

How long is the shaman? I might start a p tunnel, but want to use a hull I already have.

GG,

Shaman is 31.5"

 

[ggeiselman]

Ok Thanks

 

[TUNLBOTR]

Gotta get with Bill and finish the P Lynx, Next is a Shaman FE.... Can we have mod vp fe?

 

[HTV Boats]

How long is the shaman? I might start a p tunnel, but want to use a hull I already have.

Gary,

A Shaman is 31" long vs a Lynx at 29". Inches don't allways tell the tale as my 32" .45 hull has proven itself as a rough water hull against some 36" boats. Total weight is a better guage. Jay ran a "P" ltd/spec Shaman at the FE Nationals and won heats plus setting the low time on a short 8 lap course. In bigger water on 6 laps like Charleston I preffer the larger boat. Yes a Lynx will be faster but won't carry speeds through the corners and survive water that the Shaman will. My Vision is lighter and faster also but I would take the Shaman every time in a heat race. You might be surprized how little you give up on the big end to get handling. The Shaman also will work as a full "P" but your back to being careful around the course. Everyone thinks their driving skills can handle all the speed after they test and go through corners without any other boats on the course. That line of thinking keeps me racing succesfully.

Mic

 

[HTV Boats]

Gotta get with Bill and finish the P Lynx, Next is a Shaman FE.... Can we have mod vp fe?

Mod VP FE!!!!! That would be very interesting. I'm in if you keep it "P" spec.

Mic

 

[RonShaw]

kv_voltage1.pdf

Maybe this will give you a better understanding of KV - voltage and unloaded rpm potential. Just cause you can turn 40000rpm does not mean the prop will be efficint with the same percentage of slip at higher speeds. At some point the blade speed is going to blow up in cavitation.

Another thing to consider is making power as your volts go up the amperage draw goes down so a "Q" does not need to draw as many amps to accomplish the same performace. When you get to 8S and 10S setups your controllers don't handle near as much amp loads. But weight and larger battery capacity come into play besides just cost. What we are trying to do is within 6000mah of battery to run the laps. As you prop down your lap times go up. So that big prop you can turn in a straightaway may consume your power in 4 laps. Balance of the total setup. 10000ma batteries are the max allowed in FE heat racing but over 6000 might be impractical in just size and weight in 29-36 inch tunnel. On a "P" spec you use 3500-4000 ma in a heat. Full "P" we don't know exact draw yet but may need conservative props to finish. "Q" again more weight to get more power. 2 and 4 engine dragsters never panned out.

Mic

Mic,

This attachment is very helpful. Thanks.

 

[lohring]

The Top Speed 3 makes a great P spec tunnel. We ran the VS-1 and it's a little small for the current speeds. I started P spec with a Pro Boat motor and speed control on a Leecraft XTR-21. My next boat was a VS-1 with the UL-1 motor and speed control. As we pushed the boats harder, things began to overheat. First the controller was a problem. More capacitors helped for a while. Next the connectors got hot enough to soften the solder joints. At this point I run the Turnigy 120 speed control with 5.5 or 6 mm bullet connectors on a Leecraft XTR-21 wood prototype. It will easily match a nitro powered VS-1 running the OS air cooled outboard. Any speed control that can stand 100 amps continuous with spikes to 150 amps will work. That makes the motor the final weak link and I'm on my second season with the motor in my spec tunnel.

The secret is propellers. As you increase the pitch for more speed you need to do other modifications to lower the motor load. Currently I run a Grim Racer 42 x 55 detongued, back cut, and cupped up. I also have a prop with slightly reduced diameter. It's a balancing act to get the best speed without overheating the insulation. The stock UL-1 motor and speed control with bullet connectors and a stock 42 x 55 prop is a good place to start. The cost as you learn isn't too high compared to full P power plants.

Lohring Miller

 

[Mark Poole ModVP]

Thanks for this thread. This is the info I have been needing. Next tunnel is an FE. Well, I say tunnel. When I get all the things needed for the Spec set up I know where it is going....in my Mod-VP. I'm in. I will have a P spec tunnel also.

I think this could be what takes this hobby to the next level in techonolgy and participation! Not to mention that losing ponds to noise would no longer be a concern. As many of you know I keep up with lifesize racing and boating. Starting in 2013 two strokes will no longer be allowed on many fresh water lakes, which is nothing but stupid envriomental hysteria. Can't fight city hall, but looks like we have a great alternative in FE.

 

[Doug Smock]

Maybe some of the other FE Tunnel guys will chime in as well................

Ron, the advice given above was spot on. Start with a Spec./ Limited boat and go from there. Check the rules where you plan on racing as some areas limit ESCs in the limited classes. IMPBA D12&13 for example.

You can't go wrong with the Aquacraft UL-1 motor and ESC. Batteries you get what you pay for. If you are a serious about racing in the class, buy quality cells, take care of them and they will last you for a few years.

If I can help you in any way let me know.

[email protected]

Doug

PS You fellas get your Limited boats built and come chase me around the cotton field in Nov. :lol:

http://www.intlwaters.com/index.php?showtopic=47086&pid=425388&st=0entry425388

Bring your P Boats for the Open class! B)

 

[HTV Boats]

The Top Speed 3 makes a great P spec tunnel. We ran the VS-1 and it's a little small for the current speeds. I started P spec with a Pro Boat motor and speed control on a Leecraft XTR-21. My next boat was a VS-1 with the UL-1 motor and speed control. As we pushed the boats harder, things began to overheat. First the controller was a problem. More capacitors helped for a while. Next the connectors got hot enough to soften the solder joints. At this point I run the Turnigy 120 speed control with 5.5 or 6 mm bullet connectors on a Leecraft XTR-21 wood prototype. It will easily match a nitro powered VS-1 running the OS air cooled outboard. Any speed control that can stand 100 amps continuous with spikes to 150 amps will work. That makes the motor the final weak link and I'm on my second season with the motor in my spec tunnel.

The secret is propellers. As you increase the pitch for more speed you need to do other modifications to lower the motor load. Currently I run a Grim Racer 42 x 55 detongued, back cut, and cupped up. I also have a prop with slightly reduced diameter. It's a balancing act to get the best speed without overheating the insulation. The stock UL-1 motor and speed control with bullet connectors and a stock 42 x 55 prop is a good place to start. The cost as you learn isn't too high compared to full P power plants.

Lohring Miller

Thanks for adding some great points here. The GR42X55 seems to be the bread and butter prop for spec class. We have been pushing GR42X66's and M445's but I am sure at some point we will be replacing components. I don't even want to start a controller issue but some places here on the east coast you will need to run the Aquacraft 60a to be legal. Good or bad idea is another thread but just letting you know a few IMPBA districts are limiting esc's. The AQ 60a ESC has performed very well and is everything you need to know. (take it to a new thread if you want discussion as it will get heated) We here are just trying to get FE spec off the ground and open up the power progression that is sure to follow with knowledge.

Electric motors especially brushless are amazing, when the application and load are engineered correctly. Only bearings to wear out.(balanced system my word). My pool pump and or your air conditioner or furnace motor runs many hours day in a day out flawlessly. Sure you replace a few but not that often. How many nitro rods,pistons and even glow plugs do you go through? As Mark said this may be the future of our racing. Your call on what you like and I have run gas nitro and FE.

Mic

 

[Bill Britton]

You fellas get your Limited boats built and come chase me around the cotton field in Nov. :lol:

Bring your P Boats for the Open class! B)

Doug

We may just do that!

 

[HOTWATER]

I recently built up a Vision P-Spec tunnel (had to mod it from nitro to FE)...best tunnel I have ever had! Running the AC UL-1 Motor (2030)/ESC setup, OS lower with Kris Flynn's FE conversion.... and works very well!!

Click on "My Gallery" below to see my Vision build pics......

-Kent