Cavatation??

[M.M.]

Well this past weekend was the maiden voyage of my DF copy. I was happy with it but there was one major problem. I could not get the boat to "bite" the water. It would not get on plane so i had to push it, once it was going it was alright but with more prop i feel it would be mucho faster. :w00t: So do i need more diameter or pitch or both?

What would be some good cheap props just to test with for now? Preferably plastic just untill i find what works well, then ill get a S&B.

The boat is a 25" mono, powered by a 2881kv 380l sized motor. It also has a turnigy 120A speed controller with two 3s wired in parallel. None of the electronics were even warm after the run either. :help:

[M.M.]

Well i am thinking of trying an octura x435, and x632

anyone?

[M.M.]

Nobody has any prop suggestions??:doh:

[Diegoboy]

How about a picture of the business end of your boat. There may be more than just a prop issue. It'll help get more participation when we can get a better idea of the situation.

[M.M.]

here ya go:

http://img.auctiva.com/imgdata/3/2/9/7/6/4/webimg/167702851_o.jpg

[Jesse J]

what prop were you using that caused the prob? That motor seems a bit small for that hull too. I would go with a 540L can if possible, or try 435, 438 and 440. I bet a 440 will get you out of the hole.

How were speeds once up?

[M.M.]

The prop i beleive is a 430, and when it was trying to get on plane it would just barely move, but you could hear the motor revving like crazy. Yes i know, but i want to run his motor till it dies then i will probably get a 13xl. :thumbup1:Once i pushed it and it got up on plane it moved ok, but seemed to top out fast. So i think i definently need some more prop.

So for testing how would a x435, and x632 work?

[Punisher 67]

This is just an observation but your tabs look to be angled down , Check that . Also we were having issues getting more speed out of a DF29 so when Ken (KSM2001) REMOVED the tabs altogether his gain was almost 20 more miles per hour with a slightly larger prop . Ken is getting 57mph out of his DF29

[Diegoboy]

...see? A picture is worth 1000 words. :thumbup1:

[Meniscus]

Depending on the manufacturer of the 380L, you could also try advancing the timing up a notch after you try the suggestions above.

Personally, for the size hull, I'd try an x432 if you have one, but I admit, I don't have any experience with this hull, rather I have read a lot about hulls in this range and many folks have success with that prop. However, with the lower KV motor, the x432 may still be small.

[HOTWATER]

The strut and drive dog are too close together...you need to have about an 1/8" gap between them. When the motor spools up, the flex cable will get tighter and the drive dog will be drawn into the strut! Whith that note...you should check and make sure your drive dog is still tite and not spinning on the stubshaft...did you grind down a flat spot on the shaft for the drive dog grub screw to bite on?

Also, you should put a zip tie or a peice of fuel tubing around that water line/ fitting on your rudder...:thumbup1:

-Kent

[Meniscus]

The strut and drive dog are too close together...

Good call Kent, I didn't even notice that. :laugh: I was too busy looking at the other hardware and the angle of the trim tabs.

They also have spring loaded fuel line clamps that Diego found at the LHS. He may be able to provide the manufacturer's name. I'm thinking it's maybe Dubro, but I don't remember off hand.

Ben

[M.M.]

The way my set up works is that the flex cable is squared on the end, which then slides into the propshaft. So when the flexi cable shirinks it slides within the coupling. (kind of hard to explain, but i know that its not that)

I beleive that it is a 1/8 shaft so the 435 seems to be a good choice so far, and i was thinking a 632 would also give me some more pitch. This way i can figure out if i need more diameter or pitch.

So what is the view on trim tabs? Are they neccesarry? Should i remove them?

[HOTWATER]

Good call Kent, I didn't even notice that. :laugh: I was too busy looking at the other hardware and the angle of the trim tabs.

They also have spring loaded fuel line clamps that Diego found at the LHS. He may be able to provide the manufacturer's name. I'm thinking it's maybe Dubro, but I don't remember off hand.

Ben

Hey Ben!

Those spring clamps would be great to have! LMK where Danny found them...

Ahh...square drive...not sure on that...but I would still check out that drive dog...Just to make sure it's not spinning on the shaft...Just trying to help on some small thing that can make a world of difference...:thumbup1:

Also, I would keep the tabs...they will be a huge help later in dialing in your setup...

-Kent

[M.M.]

Yes there is a notch that was ground into the propshaft so that the drive dor will not spin. However, one problem i was having was the flexi cable spining inside of the coupler, but some wrenches took care of that:thumbup:

How should the strut be adjusted? for example when should i move the angle up or down?:huh:

[Diegoboy]

Those spring clamps would be great to have! LMK where Danny found them...

-Kent

Here (http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXK141&P=7) ya go. They are made by Great Planes. I love these things!!

[HOTWATER]

Yes there is a notch that was ground into the propshaft so that the drive dor will not spin. However, one problem i was having was the flexi cable spining inside of the coupler, but some wrenches took care of that:thumbup:

How should the strut be adjusted? for example when should i move the angle up or down?:huh:


When you angle the strut down, the front of the boat will drop down (up will lift the boat up)...How is the boat running? Flat? Bow up? down?

As someone here suggested, you should try and set you tabs level with the bottom of the boat...for now...just get the boat planing the way you want it to run FIRST, then try some tab adjustments. Adjust ONE thing at a time with SMALL increment changes...

[NativePaul]

In plastic I would go for a Y534p, if that works out OK an X435 is probably the way to go.
I spun a x431p on 3000kv 3s on a 30A controller with 43A peaks average about 30A, an X632 was 56A for peaks and I didn't do enough testing with it to get an decent average as I didn't want to blow my 30A ESC, this was in an 18" 730g cat so your amperages will probably be higher despite the slightly lower KV. The X632 offered higher speed and better acceleration at speed but also a deterioration in the hole shot, which was no problem for my little cat but is not what you want so go with diameter instead of pitch.

[HappyOne]

I have the same boat (running an Ammo 36-50- 2300 on 2 x 2s in series) and have just started to play with the setup. The boat came to me with a two blade prop and the trim tabs were down a bit plus the prop was angled down. The SuperVees put it to shame - even when I could get it to hook up.

So far we have changed to the 3 blade SuperVee prop, brought the trim tabs up to neutral and angled the prop up a bit so she won't run quite as wet. Hooks up right away and throws a heck of a rooster tail now :laugh:

More work to be done in the set up.

Where are you putting the batteries? They seem to need to be down the sides of the hull, on either side of the motor or else the hull runs too wet.

Also, the tray that comes mounted in front of the motor seems to be a better place for the ESC than the batteries.

[bustitup]

I just want to give my input on your boat MM.....its a fantastic and proven contender.....lots of guys have had great success with that hull....when you get things ironed out you will love it

when you mentioned "squared end"....are you talking about the prop shaft where the squared end flex plugs into it?.....if so I was thinking that should be soldered or jb welded somehow....but i don't know..I have almost the same boat I am building and need to know this also

also if that is the same flex and prop shaft I have..the prop end of that prop shaft has no threads and the bullet is just held on with a grub screw...seems like a problem spot to watch out for

GL man

[bustitup]

This is just an observation but your tabs look to be angled down , Check that . Also we were having issues getting more speed out of a DF29 so when Ken (KSM2001) REMOVED the tabs altogether his gain was almost 20 more miles per hour with a slightly larger prop . Ken is getting 57mph out of his DF29


Peter do you have a picture of a propper starting point for turn fins....I have mine angles back a little bit...should they be way back?

[HOTWATER]

Here (http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXK141&P=7) ya go. They are made by Great Planes. I love these things!!


Thanks Danny!

[B-DAWG]

I have the same boat. My set-up is 3S 6500 30C, cc hydro 120, Medusa 028-056-2800V2, Octura X440. My boat puts the supervee to shame and the Miss Elam also (nether boat can catch it)! Temps are a little high for my liken so I'm going to prop down one size to X438. My strut is all the way up and trim tabs are at neutral. Once you get a better motor she will get all the way out the water and still handle a 100 times better than the supervee. What batteries are using. I also have my batteries in front of the motor I need the weight up there.

[M.M.]

Well i am running two 3s 2200 25c lipos in parrellel on either side of the motor. Right now i have my trim tabs flat with the bottom of the boat, the turn fins are swept back a bit, and i have the strut angled up a bit. Eventually i plan on changing the motor, and i want to go to a piano wire drive. :thumbup:

[HOTWATER]

Well i am running two 3s 2200 25c lipos in parrellel on either side of the motor. Right now i have my trim tabs flat with the bottom of the boat, the turn fins are swept back a bit, and i have the strut angled up a bit. Eventually i plan on changing the motor, and i want to go to a piano wire drive. :thumbup:

Here you go Jeff W....the stage is yours...

[M.M.]

Oh yeah, and i have decided to just get regular props rather than plastic.

[B-DAWG]

Is there any binding on the driveline? When I first got mine I had sand the strut smooth (knock the paint off) so it would turn smoothly and grease everything. Have tried to stack the batteries up front? Post some pic's of the inside. Sorry hotwater just trying to help out.

[HOTWATER]

Is there any binding on the driveline? When I first got mine I had sand the strut smooth (knock the paint off) so it would turn smoothly and grease everything. Have tried to stack the batteries up front? Post some pic's of the inside. Sorry hotwater just trying to help out.

No worries! You are a good man for trying to help out!!:thumbup1:

-Kent

[M.M.]

Is there any binding on the driveline? When I first got mine I had sand the strut smooth (knock the paint off) so it would turn smoothly and grease everything. Have tried to stack the batteries up front? Post some pic's of the inside. Sorry hotwater just trying to help out.


Well i have not tried to move the batteries much, because i had them set so the boat is almost perfectly balanced front to back. And i have not noticed any binding, and i lubed up everything. :cool2::rofl:

For some reason i am having trouble with pics, i will get them up later.

[B-DAWG]

Here some vid of mine with the stock FSD motor and stock prop (S&B). I had the 3S 6500 mAh 30C and cc hydro 120 esc in there. I get around 9 min. of run time.


http://i204.photobucket.com/albums/bb187/bobbyr76/th_004-48.jpg (http://s204.photobucket.com/albums/bb187/bobbyr76/?action=view&current=004-48.flv)

[HOTWATER]

Cool Rooster tail B-DAWG! She looks good!

-Kent

[RPC1]

X632, Y534p, X435, X438. I would try the X438 or the X632. The X438 would be better to get your boat out of the water. I have a 21" Scat Cat with a Feigao 380Xl on 3s with a GrimRacer 36 x 55 http://www.offshoreelectrics.com/proddetail.php?prod=dh-aqub9700.

[Jeff Wohlt]

Bigger motor-- L series around 2700 kv, bigger Dia prop (438), pull trim plates all the way up to start out with. Install 1/16 wire drive...run 3S and at least a 90A ESC and fly.

Should be ballistic.

[M.M.]

theonly eason i am running 3s right now is because of the motor. When i get my 540L or XL i plan on running my 5000mAH 2s in series. So what Kv motor would work well with both sets of batts?

[Jeff Wohlt]

You are just asking too much out of the 380. The 540L would be great and if you are running the 3S2P then you should be fine as well even with the 540. The reason is the 438 is still pretty small for the hull yet the 540 will have no problem spinning it with much more torque. Probably can move to a 440 after you see how the runis.

It will boogie and then you will use your tabs to get it to stay on the water and not have any chine walking.

With 4S you will want to stay around 2300 KV or less. Same prop....438 but the 5 series is a good one.

[Punisher 67]

Peter do you have a picture of a propper starting point for turn fins....I have mine angles back a little bit...should they be way back?

No I don't sorry but from his picture the turn fins look to be where I would have them also , I am no expert but the way I see it the more they dig in the sharper your turns , angle-ing them way back may lessen the boats turning ability . once again I am no expert here . setup at times is still a mystery to me........:tongue_smilie:

[785boats]

M.M.
I too have this little Hull & have put it through a few different setups of motors & props after ditching the original 2700kv out runner that came with the boat from R2 Hobbies. All on 4s lipo.
Sv 27 package with X645, Ammo2300 with X440 & Grim racer 40mm x 52mm/3blade, Feigao 8XL with X645.
The best speed of 45mph was with the Ammo & the Grim racer prop.
watch the square socket in the stub shaft with increased power plants. I've split three of these & the flex spins in the socket. Two in this boat & one in a cat.
I've replaced the stinger in this hull & soldered the one in the cat which is the same strut setup as yours.
This is what seems to be the best setup in my boat if it's any help.
Trim tabs level.
This hull has a hook built into the hull so use a straight edge long enough to reach the front of the hull or you will end up with the tabs angled down.
Strut angled up about one, to one and a half, degrees if you have the batteries beside the motor.
Turn fins.
With the hull sitting flat & level on a bench The tips of the fins are about 3/8" off the bench.
This keeps them out of the water on the straights & dips them in on the corners.
Here's the boat with the Ammo in it on an X637 prop.
http://www.youtube.com/watch?v=WNhjkAXMxlM

Hope this helps a bit.
Paul.

[HOTWATER]

Hey Paul! That thing is dialed in just great! Very good advice on the subject too! :thumbup1:

-Kent

[M.M.]

:thumbup1:Thanks for the info Paul.

[785boats]

No problem M.M.
Thanks Kent.
Of course every boat is different & you'll still need to play around with the settings a bit.
All the best.
Paul.

[M.M.]

How would this motor work on 3s and 4s? With a turnigy 120A ESC.
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=6678

or this?

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=6679

[ozzie-crawl]

wouldnt touch them motors would go with the proven ammo 2300 on 4s or if you want a real missile a 8xl

[M.M.]

Really? One of the ones i posted was a 9xl. I have heard that they are good motors, and the only thing you have to do is glue the endball on.