6s OBT motor feeler thread

[David Kingston]

Just a feeler thread to see what people might run with a 6s OBT.

Hull is a Vision 40.

MGM 250amp (3-8s) ESC

Lawless 7.5 lower modified my Kris Flynn.

6s/1p lipo setup...

My motors that i have for testing are.

1527/1y

1527/1.5d

1521/1y.

Open for other motors other than Neu.

Needs to run the full mile oval, or here in Aus its 1500m oval

Would like to use props that are already suited to 45 nitro OBT's - 47 - 50 odd millimeters.

I have already good some good tips from other boaters but would like to also hear others thoughts.

Regards

Dave K

 

[HTV Boats]

David,

Look forward to hearing any results you get in testing. The 40 Vision is a very capable hull. In running mod 45 nitro tunnels we spin 47-50mm props at 24000-28000 rpm with nowhere near the torque you have in your Neu motors. 45 tunnel design with current nitro power is pretty close to maxed out for speed and handling. You can hit the 60 mph range but handling deteriorates as speed goes up. A 6S FE will push the envelope even further. I think a 4S will power most 45 tunnels comperable to existing speeds.

Using a 1500kv motor at 22.2v you get no load prop speeds at 33300 rpm. Spin a X450 or 1450 with some load loss and your still 5000 rpm above present nitro speeds. Can you make it handle? No harm trying. You might consider just going to 5S with these motors bringing down rpms and less likely to overpower. I am starting to lean twords 1200-1300kv range with a 6S. With my limited testing of a 1400kv motor I don't think 48-50mm props will work well. Depends on the hull and setup of course. I know I am going back to 4S for a bit and see what happens from there. FE just has a lot more power than I though it would. Going to be interesting and I hope a few more tunnel heads will share their data.

Mic

 

[lohring]

David

See the discussion on proposed electric replacement for 7.5 nitro tunnels. We're running 6S power with limited current to keep things inexpensive. The boats are just as fast as the 7.5 nitro tunnels with the same props.

Lohring Miller

 

[Jim Caldwell]

On 6s the Nue 1527 1y is the choice for 50 mm props.

On 4s the 1521 is the one.

the D winds are harder on ESC's

 

[lohring]

Your Neu motors with a high current ESD will seriously overpower a 40 tunnel. We use a Turnigy 180 and keep the currents around 100 to 150 amps. The Scorpion outrunners seem very durable so far, unlike some less expensive motors.

Lohring Miller

 

[HTV Boats]

Your Neu motors with a high current ESD will seriously overpower a 40 tunnel. We use a Turnigy 180 and keep the currents around 100 to 150 amps. The Scorpion outrunners seem very durable so far, unlike some less expensive motors.

Lohring Miller

I totally agree that these motors are overkill but if someone wants to power up at least it's usable data. May be one reason .60 - .80 tunnels don't always dominate open tunnel is there just are not bulletproof hulls that can handle 60+ speeds around a course.

The Leopards were using are also relatively inexpensive. Lohring, where are you getting the Scorpions and does someone make cooling cans for them. looking at the specs I really like the cans are not all that long. The 1521 and 1527 are 84 and 101mm tall. My leopard at 82mm I want on a 45 lawless to lay it down a bit. Kris Flyn needs to make a mount kit with shorter cable like he's doing insetting the motor coupler down into the lower.

Hoping we can find motors that will allow using the T-180 and Swordfish 200 controllers that are relatively cheap.

Mic

 

[David Kingston]

This boat wont be a ballistic missile.

It will be propped so its fast but also stable, regardless of motor.

I know from testing in 6s sport hydro a 1527/1y can pull 55mm prop and thats over kill for speed with a PTSS45 hull.

I am limited to what size diameter i can run with the motors. The neu motors are 40mm dia, and i can only fit about a 42mm dia motor on the 45lower.

As for racing - this will race yes. It will compete agains 45 OBTs and twin 21 OBTs in the 45 class. The only other 6s OBT that is currently being build in Aus is Kris Flynn's. Doing it cause we are both nuts on OBTs. (kris maybe more :blink: )

Ive got a mate who i will be doing some testing with in a weeks time and he has several other Kv motors we might try on there. I will definatly post a report on it then. I only just finished the ESC and Servo setup in the hull, so all i have to do now is select a motor and prop and go test....

I like your feedback guys. Keep it coming. I will get around to taking some pics of the boat today and post here.

oh and last reson it wont have to much Amp draw and be a ballistic missile is im using Flightmax turnigy 5800 6s lipos. Not the best but they were cheap enought for me to give them a go and so far they have held up ok in my other 6s setups.

Dave

 

[lohring]

The full discussion with pictures, specs, and sources is here:

http://www.intlwaters.com/index.php?showtopic=46440

Brian Buaas' tunnel runs in the high 50 to low 60 mph area on 1450 props.

Lohring Miller

 

[David Kingston]

thanks Lohring.

Are you guys running 1p or 2p with your tunnel setups.

Mine will definatly be a 6s/1p setup.

Any how, by this time next week i should have it tested....

Dave

 

[lohring]

David

We're running 1P. I used 2 3S 5000 packs because Hobby King was out of 6S at the time.

Lohring Miller

 

[David Kingston]

Finally got the boat on the water last weekend.

Didnt get to test with the setup that i wanted to but never the less.

Setup was

1527/1.5d

4s

x646/3 prop

Speed was really good. Cells warm, ESC cold - just had fan cooling on it, motor COLD as. Need to settle it down a bit if i was to attempt 6s on it. Definatly going to run a 1521 with lover KV - help with the weight and the make it run nice on 6s.

Very please with the running of the boat even though i did only run it for a few minutes.

Just have to decide on motor.....

1521/2.5D 1,200kv

1521/1.5Y 1,050Kv

23-26000 RPM so what nitro motors do and props will be the same wich makes life that bit easier also since i have that size to test.

Well it will be a while before i get it on the water with a different motor and 6s but i might try 1527/1y and a baby size prop on 6s before then. Dial it in a little more.

ROCK ON

Dave

 

[HTV Boats]

David,

Good info and I am sure you have more power than you need. On the 4S I would try a M447/2 or even a M or X445. Or a Grimracer 45X68 as it will probably settle it down more than an X series. With 2300KV and availiable hp overkill it should be into the 60mph range easily as your not going to load that motor much. I have never had good luck with 6 series props on larger tunnels. We will be running a Nue 1515/1Y 2200kv this weekend and with the shorter lighter motor we will see what it will turn. Hoping to get some lap times on a course.

As for the 6S I like the choice of a 1521/2.5D. Don't be affraid of the "D" motor winds. Just more torque on less timming. Should pull the larger props easily and your boat is not heavy or large enough that it should overload a 1521. Keep working and thanks for sharing info.

Mic

 

[lohring]

More rpm on a smaller prop might be good. I tried slightly larger props on my setup and the boat couldn't handle the torque. It's marginal with 50 mm props. I considered the Leecraft XT-460 to be the right size boat for the NAMBA P (4S) tunnel class. It only needs a little off the sponson tips to make the length limit and can handle the power of a full P setup. Fortunately, everyone is running P spec tunnels in my area so the traditional 3.5 size hulls work well. This was an attempt to test lower cost power plants for the larger tunnels. I don't know what rules you run under these days, but I'm interested in ways to directly control actual power, volts times amps.

Lohring Miller

 

[HTV Boats]

I really like the simplicity of the proven "P" spec or OPC class setup. I feel some of the .21 hulls are marginal with power availiable. As a full "P" many 45 hulls will work. The lenght rule in Namba for tunnels is skewed as many needle nosed hulls have sponson lenghts that could be easily trimmed. My own hull does as well or better in rough water than many 34-36" hulls and it's only 32". Just wider shorter sponsons. Cutting sponson tips would also not ruin handling on many hulls. As for limiting power not sure what is the answer. To get a larger FE class here we are going to just run it as P-Q combined and I don't see any large advantage for quite a while. Only needing "P" 14.8v packs and be able to compete in 2 classes might be a draw. 1515 Nue is under $200 and will work with a $100 T-180 or Swordfish 200a. Even in an open FE tunnel class going to an 8-10S will need a lot more cash upfront and with the extra weight much like gas tunnels their performance won't be all that great as hull technology isn't there yet. How many people are going to spend all that to compete against "P-Q" boats.. 3watt/3000w limit motor and 200amp controller would keep anything over a 1521 Nue out. Or make it an advertised less than $200 motor and $100 ESC class and review for inflation yearly. Put the manufacturers/dealers into competition keeping these costs availiable. FE tunnels are going grow here in the east sooner than people think. Hearl already coined the term "Sparkie boats".

Mic

 

[TinoAlmanza]

Hearl already coined the term "Sparkie boats".

Mic

Maybe he could name his next boat "Aye Poppie"

It's great news that the FE tunnels are going to take off, thank you all for the great work.

 

[lohring]

Brian Buaas ran his P powered Top Speed 3 tunnel well over 70 mph at Legg Lake and he thinks 80 mph is possible with full P power. That's with a 30" boat. I heat race against that same boat with a P spec power plant and get soundly beaten. I'm running a stretched out (29") wood Leecraft XTR-21 prototype built with frames from Mike Hughes. So far the new Top Speed is the boat to beat since the VS-1 can only run as fast in perfect conditions. The P spec power plant is becoming a great 3.5 substitute. P spec riggers are now running over 60 mph and I can keep up with Jerry Dunlap's VS-1 powered by an OS air cooled outboard. Propellers are the secret and Brian is the master of electric props.

I would like to see the spec concept expanded and more classes running the P spec power plant. P spec sport hydros ran at the NAMBA Nationals and I think P spec monos would make a great class. The secret to electric cost control is higher voltage with lower currents. So far the answer to restricting current is a $60 fuse (the UL-1 motor). Does anyone have a better system?

Lohring Miller

 

[Mike Luszcz]

Not sure what your speed goals are, but holy crap, you are talking 65 to 75 mph setups on 6s. I have been 72.5mph with a simple castle 1520 1y on my QS370 and that was full speed for only half the traps. 5s is really all a 36-38" tunnel needs, you will spend more time upside down than finishing heats. Just giving my opinion as I have spent a lot of time working with tunnels in the 4s to 10s range. Mike

 

[Mike Luszcz]

Another thing to expand on is prop diameter. David, I saw you asked how the boat will handle prop diameter with FE power. The problem I was having with the larger props is the heavy amount of torque roll big props cause. They will lift one sponson and make transitioning from low speed to top speed very difficult. I usually like following Doug Smock's rule of low pitch- high diameter in FE applications to reduce amp load, but the big power tunnels have not responded well to that roll effect, so its going to be best using 1.6 pitch low diameter props. 6s, in a tunnel, believe it or not, is very violent, 10s is just balistic and unessessary, believe me, I have experienced it! Haha. It will be interesting how the Q setups blend in with the .45 nitro counterparts. The P-limited tunnel class really is the best balance for heat racing. Its fast and stable. Anyways, hope this helps some, Mike

 

[David Kingston]

Well ran the tunnel for second time on weekend.

First time was with 1527/1.5d on 4s and 646/3 prop. Was good. Yesterday I ran 1527/1y on 6s with a mild prop for this motor... A x448

Really happy with the boat. Speed is great. Ran well in the rough water and great speed. Very easy on gear also. The MGM 250 amp never broke a sweat. Cells cold. I also tried a x450/3 prop on it. Off tap!!!!! Very fast boat which is one for prefect conditions only. Did some nice aerobatics on back straight. Prop change back to the 448 and boat was happy again.

Boat could do with slightly less motor rpm but whe. Propped accordingly it is fine. Im defiantly keen to get the boat back out on the water and do some more testing. Id like to try the 1527/1.5d on the back again with the 448 and see what it can do. Considering it only is a 2 minute job to change things over. 2 motor bolts, coupler, and 3 power wires.

Tunnels rock - very happy with the vision 40.........

I would like a 33inch and perhaps a 38-40inch one...

Dave

 

[HTV Boats]

David,

Sounds like your doing pretty well with lower KV's and larger props. I have been running a 1520 Castle 1600kv on 5S with a m445. Turns an m447 easily buy with battery space limited to a 5300ma battery to make a full 6 lap heat I am staying down on prop. Will actually run it in open tunnel next weekend and will see how much battery if any are left after a heat. In just making laps not on a course 3 miniutes of run time took the 5300 battery down to 15%. What are you using for batteries and with a 1527 can you make 7 laps? one mill and 6 to finish. No doubt performance is good but now we have to transfer to actual heat racing.

Mic