RC Boatworks Top Gun

[oscarel]

Last month I thought I'd buy myself a new toy for my bday and I ended up buying this beauty (http://www.rcboatworks.com/RonBucktopgun_II-3.jpg) in all yellow. I figured I could run a Neu 1527 1.5Y on 10s to be in the mid 50's since it wasn't much longer than the old Hydro Sport I had. Well, the 1527 looks tiny in this thing and I was reading FighterCat57's build thread from last year on a Sprint Cat this same size and I'm rethinking since I also have two 1717's left from the Castle sell and I'll run them on 6S2P per motor starting with CR X447's. All help is appreciated and here's my shopping list.

RC Boatworks Top Gun 42" X 16.5"

2 Castle 1717
2 Swordfish 240hv
2 3/16 Speedmaster stinger struts
2 .078 wire drives with 3/16 shaft will swap out for .093 when couplers arrive
1 Speedmaster 40 rudder w/ 5" setback
1 Hitec HS-5805MG - now using Hobbico CS-170 smaller size same torque
Motor mounts will have to be made

So here are the first couple of questions I have, for the struts is 3.25" long enough?

[oscarel]

That's a HOTR 32" cat sitting on top if it! These are with the 1527 in there.

[oscarel]

And this is with the 1717 in the sponson and 4 3S batteries behind and ESC on side. Motor is centered on the 30% mark and it balances with the batteries where they are minus struts and rudder.

[RandyatBBY]

It reminds me of my 41 inch Striker cat. i race it on 10S with a 2230 1Y, lots of fun! I was real surprised with the 1527 1.5Y it pushes a 1/8 scale hydro real well.

[oscarel]

Well, I went ahead and started with the twins so that I wouldn't second guess myself later. I'm sure I'll find something for the 1527 later. What does your Stryker weigh with the 2230? Are you running 1P? Also I think I'm going to go with a 6S3P setup paralleled to both motors to try and save on a set of lipo's.

[oscarel]

Struts and rudder came in today, mocked up. I went with the 3/16 struts since OSE only had 1 of the 1/4.

[RandyatBBY]

If I remember right it it was in the 16 pound range. I ran it on 10S2p. Speeds were in the high 60ties.

[Brushless55]

I dig the looks of this hull.. :thumbup1:

[oscarel]

Thanks Brushless, I'm hoping it runs which it should with these motors. I've got the struts and rudder in and one CF mount made. Boy cutting this CF sucks! I burned up a Dremel tungsten bit and a scroll saw blade. I ended up just using a metal cuttoff wheel and free handing it.

[oscarel]

If I remember right it it was in the 16 pound range. I ran it on 10S2p. Speeds were in the high 60ties.

Wow, that's not bad! This hull weighs 10lbs empty so I'm sure I'll be close to the 20lb mark once it's done. I'll be more than happy if I get to those numbers!

[oscarel]

Got a lot done today, stuffing tubes in, motor mounts in, incoming cooling lines done, steering servo mounted. I got a little carried away with the hot glue gun on the rudder and I'll go back and clean it up later. 1 esc mounted with velcro.

[ctstike]

nice boat! how can u build boat i mean wer i can find the scorpion out runner and turnigy lippos 7s?

[oscarel]

Well, you find the boat you want, search here to see what others have used, buy what you can afford then start building. www.innov8tivedesigns.com sells Scorpion or you can google search. Hobbyking.com sells Turnigy.

[oscarel]

Maiden run today wasn't that great. First I had issues with the set screw couplers but I got that fixed. Now it runs extremely wet and I've got the batteries as far back as I can, so I'm going to move the motors back a few inches. When I originally set it up I marked what was suppose to be 30% but I got my math wrong so now I'm setting it up so that with the batteries all the way back it's at 25%. Eagle tree showed speed of 37 so I've got a lot of work to do, this thing should be at least 20mph faster.

[keithbradley]

How are your temps/current draw? I wonder if a prop up would help get it out of the water and moving...
What was the COG at when you ran it? You said it was supposed to be 30% but it sounds like you are implying that it wasnt.

[oscarel]

It was 35%, not sure what I was thinking but my math turned 1/3 into 30% somehow and adding receiver battery (2200mah 3s lipo) and Eagle tree equipment didn't help either. Temps on the motors were cold, as they were when it went out. ESC and batts were only slightly warm. I didn't have a current sensor hooked up but I will next time. Yes, bigger props are also next, since I'm running wire drives I don't necessarily have to run CR props, I'm thinking of running dual 447/3 since I've had good luck in the past with this motor and that prop. I tried trimming up but it didn't help at all.

[Jeff Wohlt]

You do know those couplers I sent were .093...correct? I see you posted 078 wire above.

That would not be good.

[oscarel]

Yes, I need to update. I have one .093 and a temp .078 that I'm using. Once the couplers get here I'll swap out the .078. Thanks for sending them!

[Jeff Wohlt]

Should be there today. Were sent priority on Tues.

[Fluid]

It was 35%.
My Stryker F-41 didn't run well at all until I had the CG between 32-33%. With the cat flat on a flat table, where are the struts? They should be either flat on the table or better raised at least 1/4" to 3/8" above the table. You can keep raising the struts until the props "blow out" or fail to hook up. Angle the struts up at the prop end 1 to 2 degrees. All the above will help to get the bow up and the hull running cleaner.


Temps on the motors were cold, as they were when it went out. ESC and batts were only slightly warm.
How long were you running? What was the ambient temperature? No temp gun? "Cold", "warm" and "hot" are terms so relative they are really meaningless.


I'm thinking of running dual 447/3 since I've had good luck in the past with this motor and that prop. I tried trimming up but it didn't help at all.

With twins you normally run a larger prop than you do with the same motor in a single application. Rather than x447/3 props try CRx457s. If they are too much, cut the diameter down to 55 or less. The prop walk you will get from two LH props will probably be terrible.



.

[oscarel]

Another run today with current sensor, the 447's are not enough as it was only pulling 140 amps combined.



My Stryker F-41 didn't run well at all until I had the CG between 32-33%. With the cat flat on a flat table, where are the struts? They should be either flat on the table or better raised at least 1/4" to 3/8" above the table. You can keep raising the struts until the props "blow out" or fail to hook up. Angle the struts up at the prop end 1 to 2 degrees. All the above will help to get the bow up and the hull running cleaner. .

I set them between -2 degrees and +2 degrees with no change.


How long were you running? What was the ambient temperature? No temp gun? "Cold", "warm" and "hot" are terms so relative they are really meaningless. .

Approximately 5 mins on 6s2p paralleled to both motors. I do have a temp sensor that I'll hook up next time. I'm in the DFW area so ambient temps are around 70.


With twins you normally run a larger prop than you do with the same motor in a single application. Rather than x447/3 props try CRx457s. If they are too much, cut the diameter down to 55 or less. The prop walk you will get from two LH props will probably be terrible..

I bought a set of CR x457's today and I'll get them balanced and sharpened and go from there, thanks for the advice!

[oscarel]

Should be there today. Were sent priority on Tues.

Thanks Jeff, the showed up today!

[oscarel]

Fluid, what motor and prop did you end up with in your Stryker?

[Fluid]

I run a Lehner 3060/10 on 10S2P/9000mAh. I've run several props, the best were an x460/3 and an x465.

How high were the struts above the table? If they are too deep the strut angle will do nothing.

Watch the motor and ESC temps with the x457s until you know they are safe.



.

[oscarel]

The bottom of the struts are 1mm from the bottom of the hull. I started with the ends of the strut touching the table as seen in this photo.

[oscarel]

fluid I just reread your post and the stingers are fixed at the transom, they can't be adjusted up only angled.

[Fluid]

I forgot you were using stingers. :huh: Not much you can do to adjust the prop depth without a lot of work. You'll need to move the CG back...why not just temporarily put the packs in the rear of the sponsons just to see if that gives you enough movement of weight. That or stack them crosswise on the tunnel two high. That will move the weight back too. Just be careful when testing to see if that frees up the hull. The bigger props may help too. I don't know of anyone who has used this hull for FE. I almost got one instead of the Stryker.



.

[oscarel]

Well X457's made a huge difference. I saw 54 with a lot of porpoising so once it's trimmed and settles down it should do just fine. I ended up breaking the .093 shaft due to too sharp of a bend so I'm going to go back to the .078's for now and see if I can smooth out the prop shaft. I left the eagle tree turned on and lost all data, but after the first 2 min run which was not all full throttle the motors showed 90 degrees, I have the seagull unit so I didn't need to download the data. And of course I didn't look at amp draw...

[oscarel]

Quick update, due to the angle on the shafts I've switched to .187 flex which just came in yesterday. Also I've switched to Turnigy t180's and they seem to have a little more punch than the swordfish, also there are more timing options so I'll start playing with them once I make sure I can keep the shafts together.

[txboatpilot]

Sounds good Oscar! Cant wait to see it on the water.. :thumbup1:

[oscarel]

Yeah, I wanted to get a good run in before calling you... I'd hate to get on the water and something else happens.

[oscarel]

Finally got a good run in today. Eagle Tree recorded speed of 65.83!!!!!! This is with 6S2P and CR X452/3's. Amps show one motor pulling 285 amps but I'm not really sure of this number because after 4mins of running packs were at 75% left. So far the .187 shafts are working but I've really had to torque down the collets. Also I lost yet another prop yesterday with one of the nuts coming off, so now they're loctited down good. Running CR 457's I had top speed of 59 with amps showing 305. I think for regular running I'm going to only run 5S2P since 65 is way too much for now...

[Fluid]

Great speed, that is right in line with the motors and props you are using. The amp draw is more problematic. If you really ran for 4 minutes and only used 2500 mAh then your average amp draw was under 40 amps. Something isn't right here unless you were off the throttle a lot more than you were on it. I assume the 285 amp reading was a peak reading? Those motors won't pull that kind of amperage running 65 mph.

And what prop nuts are you using? You should never need to use Locktite on a prop nut! Good staked nuts like Zuber nuts will last a long time and you won't lose a prop. Some cheap staked nuts (from China???) are loose and will back off.


.

[txboatpilot]

Good new! We will be at the pond around 10am tomarrow,, hope you make it out with this bad boy!!

[oscarel]

Great speed, that is right in line with the motors and props you are using. The amp draw is more problematic. If you really ran for 4 minutes and only used 2500 mAh then your average amp draw was under 40 amps. Something isn't right here unless you were off the throttle a lot more than you were on it. I assume the 285 amp reading was a peak reading? Those motors won't pull that kind of amperage running 65 mph.

And what prop nuts are you using? You should never need to use Locktite on a prop nut! Good staked nuts like Zuber nuts will last a long time and you won't lose a prop. Some cheap staked nuts (from China???) are loose and will back off.


.

I'll post the eagle tree data later today, it was late and I with the time changing I ran out of time. It was 4 1min runs since I'm down one cooler so they were SAW type runs. The prop nuts are ose-8135, there are a few things that normally wouldn't have been done, but to save losing parts I've had to do. At this point I'm just estatic I was able to get a few mins of run time without spending any more money.

[oscarel]

Good new! We will be at the pond around 10am tomarrow,, hope you make it out with this bad boy!!

I'd love to but there's too many people off this weekend. I'm going to see if I can schedule next month off.

[oscarel]

Here's the eagle tree data , I have it stop when full so I didn't get the last few runs. So just to show the eagle tree is off it shows 3400 mah used and I just completed charging the lipos and I put in 2800 with balancing. I'll get video later in the week.

[Fluid]

Your average amps is closer to 130-140 which is more like it. The 295 was a maximum, but all those max values seem on the high side to me. You would not expect to have the mAh from the Eagle Tree match the charger value exactly - but that is a ways off.



.

[Brushless55]

Your average amps is closer to 130-140 which is more like it. The 295 was a maximum, but all those max values seem on the high side to me. You would not expect to have the mAh from the Eagle Tree match the charger value exactly - but that is a ways off.



.

2800mah burnt in 4min is more like 40-45 cont.

[oscarel]

So if I highlight the first 55 secs it shows avg 93 so X2 would be, if this thing is reading correct, 180 amps average.

[Fluid]

2800mah burnt in 4min is more like 40-45 cont.
Read post #33 buddy, then read the graph. We want to know what the combo pulls, not how including how much time he spent off-throttle. That's why we use data loggers, otherwise all we'd need is a stopwatch and a charger. His average on-throttle draw is about right for the boat and speed, perhaps slightly on the high side. The spikes are quite high but may be okay considering the size and weight of the boat to get on plane.


So if I highlight the first 55 secs it shows avg 93 so X2 would be, if this thing is reading correct, 180 amps average.
No, I was looking at the amp curves. You were on and off so much you can't really use the program's "average" function. With my Castle ICE controllers I download their data into an Excel program and find best-fit curves graphically. Here I had to eye-ball it.





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[Brushless55]

Read post #33 buckwheat, then read the graph. We want to know what the combo pulls, not how including how much time he spent off-throttle. That's why we use data loggers, otherwise all we'd need is a stopwatch and a charger. His average on-throttle draw is about right for the boat and speed, perhaps slightly on the high side. The spikes are quite high but may be okay considering the size and weight of the boat to get on plane.


.

Ok buckweed
:roflol:

[Fluid]

Ah well, yet another rocket scientist for the ignore list.



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[Brushless55]

Ah well, yet another rocket scientist for the ignore list.



.

:iagree:
:roflol:

[oscarel]

I was able to get in another quickie today, this time in a bigger part of the pond and without on/off the throttle as much. The amps this time are from the other motor and they are running about the same. I was able to pick up a couple more mph, 67.9. I had my youngest attempt to video, but she got more sky and shoreline than the boat.

[Brushless55]

The speeds are awesome man!
And I'm blown away by the amps this thing burns..

[oscarel]

Thanks, I'm gonna back off now before something blows up.

[oscarel]

Here's a video from running this morning. I moved the timing down to 11 degrees just to see if it would make a difference and it didn't. Still showing spikes around 300 amps. Motor temp after 4mins was 91 and top of one cap was 107, top speed 66.6. There's a good almost flip around 50 secs and the battery came unhooked on the motor with the amp sensor, no other damage luckily.

http://www.youtube.com/watch?v=lC8EP8JOcxo

[millzee]

nice, I think I'll use the stinger struts as you have, thanks for the advice

[Jeff Wohlt]

My word for the day.

Pretentious >>>>>

displaying a self-image of being "special", "intelligent", and "different". Not content with being average, speaking in cliches. having no humility or originality.

[millzee]

My word for the day.

Pretentious >>>>>

displaying a self-image of being "special", "intelligent", and "different". Not content with being average, speaking in cliches. having no humility or originality.

Huh,???????

[Brushless55]

My word for the day.

Pretentious >>>>>

displaying a self-image of being "special", "intelligent", and "different". Not content with being average, speaking in cliches. having no humility or originality.

hmmmmm :spy:

[Jeff Wohlt]

Sorry.... It has to do with these special, stupid, childish lists. Was just the best word I could pull out of my a$$ at the moment.

But.... love the boat and run. Nice job!!

[6sHyper]

so your pulling those amps with your T180's???? man those things must be underrated!!

[oscarel]

The T180 is rated burst of 380, so it's within specs.

[Brushless55]

so your pulling those amps with your T180's???? man those things must be underrated!!

I think they are :rockon2:

[oscarel]

I had monojeff make up these graphics to match the boat from the rcboatworks page. They turned out great!

[monojeff]

Looks great nice work!!

[oscarel]

Update. I swapped out the 1717's for Turnigy TP5692 1340kv's and went up to CR X257's. I'm able to run 6s1p with these with speeds at 60mph and amp per motor average of about 80.

72434

[lenny]

Very nice job on this,:tiphat:
Looks like things are getting better for you.:beerchug:

[oscarel]

Thanks Lenny. Yes, I feel a lot more comfortable with the lower amps. But the 1717's and T180's are still going. I'm going to up the voltage and see how it does. I'm going to replace the T180's and step up to 7s.

[oscarel]

Here's a short video my daughter took.



http://youtu.be/WeaWiMj_oUg

[jcald2000]

To help avoid those high amp spikes use slower thoddle roll on when starting up or accellerating from lower speed, instead of banging on full gas.

[oscarel]

Yep, that also helps avoid wheelies.

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