A new project - Scarab 55

[David Hajj]

Mono, 55" length, 14" beam, 24 degree vee Scarab offshore design hull. It will be powered by Plettenberg 370BM/50 A1 "S", 3/16 flex cable through a stinger surface drive system, Schultze 40/160 ESC, IB4200 SHV sub-c power at 24 cell voltage in parallel / 48 cells total to a X452 prop to start. Lipo is the final power source with two 14.8 volt X 2 = 29.6 volts total 4S/5000mah 150 amp (30C) packs. The packs will hold 3.5 volts per cell at 100 amps constant!

The hull is 5.5 lbs with hatch and 1/4" transome plate installed. All up weight of hull ready to run minus battereis will be 10.5 lbs for a running weight of 13.25 on Lipo power and to 16.75 lbs on 24/2P 48 cell NIMH cells. At 16.75 lbs and 26% cg (24/2P NIMH) the hull sits just above it's displacement water line. At 13.25 lbs (LIpo 29.6 volts) the hull is very light and sits just over 1/4" above it's proper water line displacement. I expect it will be a hand full on Lipo and just right on NIMH.

We shall see how it goes.

David

[Peter Zicha]

Right on David , join the club...you and harry will have fun running together , I'm really looking forward to harry's vids at full steam ahead

[David Hajj]

Well getting started, t-6 aluminum mount, roughed in to start. Would prefer to cad design and water jet it but I think making it by hand will do fine. It will sit between 3" spaced rails with an aluminum servo mount attached to one rail. I like simple, clean "less is more designs". I thought about using carbon but weight is not a much difference and the cost / health risks working with it are not good. The mount will be cut down and drilled quite a bit more before done. Besides I am a sucker for polished aluminum!

David :cool:

[Ralf M.]

hi,
great project and good setup.
why don`t you use a 1/4" flex cable? 3/16" is critical, we killed every one of this with the 370 ;)

Regards

[Old Sloppy]

I would like to see a 1/4" cable with a 3/16" turned down propshaft.
I have one in my OPS .80 Nitro Cat. I was snapping the 3/16" cables if I jumped down on the throttle suddenly, otherwise they held up .

[David Hajj]

I selected 3/16th since I like to run the most pliable cable for the power. Racers from europe that have vast experience with the 370 tell me 1/4" is what I should use to handle the power output. On a mono with such a short shallow bend stuffing tube, 1/4" should be no problem at all.

1/4" it is.

David

Below is a finsihed gas version of the hull I am building.

[David Hajj]

Not much has gotten done. Hardware installed and some interior setup. I hope to have everything all sorted and epoxied in first of the week.

For now setup will be 24 cells 2P total 48 cells to a Plette 370/50 A1, 40/160 ESC, 1750, X455/3 to start at mid 40's speed for 5+ mins around 90 amps constant. A PropShop 4 or 5 blade clever would be interesting down the road.

David :cool:

[Old Sloppy]

I like the twin rudders.

I can't wait untill the stringers are finished.:yeah:

[Peter Zicha]

She's looking real good David

[David Hajj]

Not much more has been done, work takes all my time these days.
The setup is complete, just finishing the hatch setup this weekend.

Waiting on parts from Germany as well.

David

[Old Sloppy]

I like the way you included the ESC shelf in the stringer system.:yeah:
Very well done indeed.

Harry:)

P.S. From what I have seen you may want a x457/3 to start.
That Plett may over power a x455/3.

[K.R.Joye]

DAVE i think your going to find you will need at least 32 cells/ 2P to motivate the big Plett BL. You'll have plenty of room to add more, 40 MPH on 24 will be a challenge. I haven't seen anyone (in FE) break a 3/16 flex yet the 1/4 will last forever. Good luck with your project!

[David Hajj]

Ken,

Thanks for the info. It has been mentioned around 818 rpm/volt at 29 volts and 50 amps but who really knows. To start 24 volts at 100amps for about 2200 watts output in the X648 area of props.

This is the fun part.

David

[Peter Zicha]

From plettenberg....RPM with no load / volt: 815 1/min
current with no load about 11 V: 4,4 A

Even thou I am going to run my 57' Apache on 2 x 40 cells I think the very first run will be 4 x 20 cells just to get the feel for the boat , like I have mentioned on my preveous posts this is by for the largest and most expensive model that I have ever built ....So I for one fully understand you going the 24 cell route for the first few runs

[David Hajj]

Max,

Oh I forgot you did have info for the Plette 370, Thanks for reposting that.
My bad memory. I am with you on the early stages of running. It's a learning curve but a fun one.

David

[Old Sloppy]

To start 24 volts at 100amps for about 2200 watts output in the X648 area of props.
David


I have got to get your x648 prop back to you...:)

Harry

[MPR Arthur]

What kind of lipo's are that by the way?? 30 c sounds sick!

[MPR Arthur]

I still really like to know!

[David Hajj]

Arthur,

Here is the link to Tanic, these new cells will be appearing in other brands as well. We are getting close to a good replacement for the old Sub-C.

David

http://www.tanicpacks.com/catalog/index.php?cPath=78&osCsid=4eb61733787d000edf952a7a6c613bed

[MPR Arthur]

Thanks David, I'm impressed! I think you guys are are further with testing lipo's then at this side of the lake! The performance looks really good on paper.

[Jay_Limn]

Not much has gotten done. Hardware installed and some interior setup. I hope to have everything all sorted and epoxied in first of the week.

For now setup will be 24 cells 2P total 48 cells to a Plette 370/50 A1, 40/160 ESC, 1750, X455/3 to start at mid 40's speed for 5+ mins around 90 amps constant. A PropShop 4 or 5 blade clever would be interesting down the road.

David :cool:

Hi Dave, the twin rudder is awesome, beautifully crafted. Where I can get those? I am planning a similar setup.:)

James
Sunny In Singapore

[David Hajj]

The rudders are two Speedmaster 60/90 blade assym's with 4" extensions. I cut 1" off the bottom of each rudder, then cut the left CNC control horn off and machined it smooth. Drilled and tapped two 4/40 holes in the top of the rudders. used two Dubro hiem pivots with a Titanium left/right thread RC car adjustable steering link rod. Now it's easy to trim/adjust the rudders.

I have two 5" extentions if the rudders need to go back further but I set them with the leading edge even to the drive dog/prop. A good well proven setup to start.

Below are some figures I am working on. They will be repainted and detailed, just fitting them for now. Also a pic of a early single rudder setup I was not happy with.

Update: The last pic is my final rudder setup with water exit exhausts and cross brace. With the dual rudders I have separate water cooling systems, ESC and motor. Everything should stay cool enough even if I loose one system. Running 75 to 105 amps constant for 4 to 5 mins heat needs to be removed. Next stop, 10S 30C lipo's.

David

[David Hajj]

You are so right, the setup looks good on paper!
Just have to see it it is real and works for real.

Cheers,

David

[Jay_Limn]

The rudders are two Speedmaster 60/90 blade assym's with 4" extensions. I cut 1" off the bottom of each rudder, then cut the left CNC control horn off and machined it smooth. Drilled and tapped two 4/40 holes in the top of the rudders. used two Dubro hiem pivots with a Titanium left/right thread RC car adjustable steering link rod. Now it's easy to trim/adjust the rudders.

I have two 5" extentions if the rudders need to go back further but I set them with the leading edge even to the drive dog/prop. A good well proven setup to start.

Below are some figures I am working on. They will be repainted and detailed, just fitting them for now. Also a pic of a early single rudder setup I was not happy with.

David

Dave hi,

Thanks for the lead, nice work on the rudders.
James

[David Hajj]

Well I finally finished the 55" Scarab. First runs last Sunday. No pictures yet, maybe this weekend. Harry nor I brought a camera. I just can not take pictures running solo at the house.

First setup very conservative, very slow speed (37, 38 mph): Plettenberg 370 A2, 40/160 ESC, 10S 5000 mah lipo, X457 prop. Around 60 amp draw for 5 mins with 2200 mah left in the batteries after 4+ mins runtime, no heat at all anywhere. All up weight at 10S lipo is 11 lbs even.

Second run: Plettenberg 370 A1, 10S2P 5000 mah Lipo, X646/230 prop
No GPS data but conservative mid 50's mph for a easy 4 Min's with 1900 mah left in the batteries after 4 min runtime. Drawing about 110 amps, not bad. No heat in the battereis, barely warm motor and ESC. All wiring is 5.5 mm plugs with 10 guage or double 12 guage wire. With no rain tonight more testing. All up weight on 10S/2P lipo is 14 lbs even.

Big boats are cool

David

[Peter Zicha]

David could you post some picture of the inside of the boat , the inside setups are as interesting as the outside , thanks :) :)

[David Hajj]

I have a whole theme and graphics setup for this hull, drivers, air intakes and such. All that comes after setup and tuning is complete. I have always thought it better to complete the setup before the graphics, kinda the cart before the horse otherwise. With this hull everything is new but the same old process still exists. :confused:

Here are a few crude pics. I am not a great photographer.

Harry and I ran yesterday. The boat ran very well. Stiff cross wind and 6 to 8 inch crop with 12 inch plus rollers from the ski boats running back and forth. This hull eats rough water with ease. Harry took some shots and not sure maybe some video. The boat is fast, may get some GPS data today if water is smooth enough.

Setup for now:

Plettenberg 370 BM50 A1
Schultz 40/160 ESC
Tanic 5S/2P 5000 mah Lipo
3/16" flex shaft
All Speed Master hardware
prop testing X646, 230, X450, X648, X548, X547
All up weight on 5S/2P Lipo is 14 lbs

David :cool:

[Old Sloppy]

Harry and I ran yesterday. The boat ran very well. Stiff cross wind and 6 to 8 inch crop with 12 inch plus rollers from the ski boats running back and forth. This hull eats rough water with ease. Harry took some shots . David :cool:


I got video (Quicktime) need help with posting.
If some one will P.M. me, I will email the video to them & maybe they know how to post it.
Here are some pix for now..
Harry S. :)

[Dan]

David,Glad you got a chance to get out on the water!! Hope you had a blast!!:yeah: talk to you soon.

[David Hajj]

Yea it is great to be back out, way to long for me. Harry and I will run after dinner today to let the wind die down. Test a new battery pack I built for Harry and get a speed and prop test on my Scarab.

Can not wait until you get your monster running. :eek:

David

PS: The mono is great but "Cats" is were it's at! :yeah:

[Dan]

The monster will be built over the winter for next season.I have the Team USA cat on the bench rite now,just waiting for my contractor to finish my shop.he'll be installing the sheetrock and tape this week.A couple weeks,and it will be open for projects.I should have the USA ready for water hopefully by the beginning of October.
A couple pics here: http://community.webshots.com/myphotos?action=viewAllPhotos&albumID=553528532&security=JrgvuO

[David Hajj]

Harry and I went out yesterday. One GPS run in high wind went 49.8 mph.
Kinda slow but still impressive to watch and hear run. Trimmed out
it should be mid 50's. A little chine walk with a side wave or wind gust
at full speed. Nothing to worry about just keep the power on full to
drive right through it.

The hull has excellent rough water handling and Tom at Expresscraft did a beautiful job building the hull. Best American built RC boat hull I have ever owned.

Running trim is still with the nose pinned down. It turns on rails, no turn fins needed at just 75% steering dialed in. A good racing setup. The Plette 370/50A1 howls like a banshee at high rpm.

I have used a Octura X648, X646/3 with this motor. Testing with a X450, S230 Stainless and cupped cut 1650
that I have on order. So far the X648 is looking good all round. About a 8 foot high wall of water off the prop, reminds me of my old nitro racing hulls.

Setup for now:

Plettenberg 370/BM50 A1
Schultz 40.160 ESC
Tanic 5S/2P 5000 mah Lipoly batteries
CG is set at 21% and runs with the nose down and level
Pulling about 109 amps at steady full load
Prop speed just about 24500 rpm
Cell temp 95 degrees
Motor temp 140 degrees
ESC temp 91 degrees
Run time 6 mins with 2100 mah left in each 5000 mah pack or 4200 mah left in the 2P config of 10000 mah total
Voltage per pack 19.46 volts or 3.892 volts per cell after run
Maintaining 3.43 V per cell at 109 amp load, 54.5 amps per pack 2P config
Cells 5000 mah 100 amp sustained load, 150 amp short duty

Harry ran his Apache on a new set of 40 4200 IB SHV's. A big improvement over the old GP 3300's and IB 3800 cells. We had a ball running with full size boats in their wakes and racing each other. It just does not get much better than that.

Anyone else please chime in with experience running FE setups in large hulls. The more I learn the more I know what I don't know. :confused:

Big boats are cool. :cool:

David

[BACKEMF]

It's hard to see on this narrow 32" boat. I did this to mine as well. Dual rudders.

Altough the boat handles better the hull itself (Graupner Arrow) is over powered.

What do you think if I use these on a Titan 29"?

Sorry to highjack for one question but duals rudders are just something I winged.

I also used the Titanium turnbucle, slightly different Dubro link though and I used an extra rudder arm and extened the 3/16" pins.

http://www.rumrunnerracing.com/feforums/attachment.php?attachmentid=9111&d=1148005927

[David Hajj]

Thats a heap of rudders you have on that hull. Your work looks great Ray! :yeah:

Honestly I would just go to the Titan 40/33" hull. Unless you want to run over 50 MPH (80.47 Kph) all the time. I like the larger hull much better. The 33" tends to "fly" near or over 80 Kph, but what smaller hull doesn't?
Ask me how I know this. :eek: I fished that hull out of the drink a bunch but it was one of the most fun hulls I ever owned. Small (fits in your back pocket) easy to deal with, fast and fun.

David

PS: Here is a pic of the Supercat M1 I PM'd you about rudder setup. Also a pic of my old Titan 40. :yeah:

[BACKEMF]

Thats a heap of rudders you have on that hull. Your work looks great Ray! :yeah:

Honestly I would just go to the Titan 40/33" hull. Unless you want to run over 50 MPH (80.47 Kph) all the time. I like the larger hull much better. The 33" tends to "fly" near or over 80 Kph, but what smaller hull doesn't?
Ask me how I know this. :eek: I fished that hull out of the drink a bunch but it was one of the most fun hulls I ever owned. Small (fits in your back pocket) easy to deal with, fast and fun.

David

PS: Here is a pic of the Supercat M1 I PM'd you about rudder setup. Also a pic of my old Titan 40. :yeah:

It fits in your back pocket huh? right... You have big pockets! :eek:

The Maritimo is the biggest I will go and I will most likely get the Titan 40, even though a close buddy said I should put all the stuff from my Arrow into a 29" Titan. A 12XL Feigao, and 18 cells....I have a gearbox.

Do you make those inline rudder extensions for anyone?? For the Maritimo that is...

[David Hajj]

It fits in your back pocket huh? right... You have big pockets! :eek:

The Maritimo is the biggest I will go and I will most likely get the Titan 40, even though a close buddy said I should put all the stuff from my Arrow into a 29" Titan. A 12XL Feigao, and 18 cells....I have a gearbox.

Do you make those inline rudder extensions for anyone?? For the Maritimo that is...


Hey, I was a pullin your leg about "fits in your back pocket" :moon:

I will make you brackets if you want some. The 29" is a great hull I just like the 33" a little better. The hatch is easier to deal with and I like the dual canopies on that hull. Your setup will work well in either hull. Hey I ran mine on just a MEGA 22/30/4 direct drive on 24/26/28 cells, it was fast. Ask Hugh he owns it now.

Take care,

David

[Old Sloppy]

I will most likely get the Titan 40, A 12XL Feigao, and 18 cells....I have a gearbox.
Do you make those inline rudder extensions for anyone?? For the Maritimo that is...


Ray,

I have the pair of inline rudder extensions David H. made, I will check with him if they can be sold...

I would recomend the 33" hull for you (Titan 40) Your 12XL will push it very well.

David's boats fit in the bed of his pickup truck...L.O.L.

Harry :)

[jevmax]

Hey David,

Did you ever get that M-1 SuperCat XL together and on the water?

Jim V

[David Hajj]

Funny you mention the Supercat XL, I was planning it to be the next project. :yeah:

I have the interior gutted and ready for reassembly. I am vacillating over a 3060/80 single or twin 370BM50 A1's on 10S lipo per motor. I have thought of a single 370 50 A1 but not sure how well it would propel the 7 lbs hull. My Scarab 55" is 7.5 lbs and runs 50 mph nicely.

If I run twins I was thinking of your configuration in the Aeromarine Avenger Pro on the tunnel not in the sponsons as the twin 2280's were previously in the Supercat XL.

I hear there are two new "cats" in town for Paul. You know they will be fast.

I hope to have the Supercat XL running soon. New job right now, no vacation but the money is good. :D

David

[BACKEMF]

Ray,

I have the pair of inline rudder extensions David H. made, I will check with him if they can be sold...

I would recomend the 33" hull for you (Titan 40) Your 12XL will push it very well.

David's boats fit in the bed of his pickup truck...L.O.L.

Harry :)


Just put a hold on them Harry, I might just get the H&M if the Egessa doesn't come in a natural Finish.

It's for the Maritimo, I thought the strut/rudder inline assembly I have from H&M was correct but it's a size under.

H&M and the Egressa Price is about the same, and H&M takes paypal now too.
The only thing is I have to modify the strut bearings for 3/16" stub... But it's sooo nice.:yeah:

[David Hajj]

Who is Egressa? :confused:

David

[BACKEMF]

Your hardware modified from The Egressa:

[David Hajj]

Oh well duh, a blonde moment for me. :eek: :doh:

David

[BACKEMF]

LOL... I'm trying H&M First, a rudder and strut will cost me $E 78.00 before shipping, not too bad.

[David Hajj]

Thats a good deal for the H&M setup. easy to convert to SAE and very good quality. Heck Speedmaster stuff in the states cost that much for a whole setup. Go for it.

David :yeah:

[David Hajj]

I have finally gotten a little time to work on the details of my Scarab. here are a few pics, not great but you get the idea. Still cockpit detail to do and a host of little things but the big stuff is done. New Lipos, a different motor, some new props and maybe everything will be ready for next weekend.

David

[David Hajj]

There are two drivers but a pic of one for now.

David

[Peter Zicha]

David your boat looks awesome , excellent choice of color and detail

[Old Sloppy]

David,
Looks great.
I can't wait to see it in person...
Harry :)

[David Hajj]

I missed you Sunday, I hope you got to run. Give me a call.

David :wave:

[G B.Robbins]

Dave/old Sloppy: From the pics did you decide to eliminate the dual rudders. I am in the process setting up the Fountain 41. It already has dual rudders, speedmaster etc. why did you change the rudder setup. I'l post some pic, if I can every get the hang of posting pics. :confused: :confused: I am only planning on sport running. Decided on a Graupent 820turbo with 20 cells.
GB
:D :D

[BACKEMF]

I would like to see your dual rudders.

NOW, in the book "Advanced RC Boat Modelling" on page 59 it shows a gas boat with dual rudders. It's a very shallow Vee boat but you can see this person has decided to angle the rudders to be at 90 degrees to each side of the Vee.

Just like turn fins, (forget that it's dual drive too for a second) and I thought I might try this. If you think about it each rudder will be like a turn fin in the corners and not creating any lift, in theory...

In the straights it would cause lift though wouldn't it??? I'm just tossing ideas around, go check yer books...!

[David Hajj]

I ran the dual rudders and yes they look cool and turn great. But this hull turns soooo well I needed to take rudder off because it turned to tight. Not hooking but this hull turns better than any mono I have ever had and no turn fins needed. So I tried removing one rudder. Still turns on rails. So I cut 1" off the 60/90 Speedmaster rudder, still turns on rails with no turn fins. That is were I am now, it is more controllable turns great, less weight, drag and simplicity. I have the rudder 1 3/4" off center with the 3 1/2" extension. I tested left single and right single and opted for the right to run on a race course. Turns right and left equally.

I have new Lipos that saved 1.25 lbs over the Tanic Lipos and the scale details, driver figures and such now make the hatch weigh 14 oz! Still the all up weight ready to run is 14.25 lbs and she sits on her waterline, rear chines just touching the water. Because of this the hull will chine walk a little hitting a wave but never gets severe and only at high speeds. Kinda nice to have to add weight for stability for a change.

Still more trimming to do but the big stuff is out of the way so I added the scale details, paint and such.

Ray - How is the Maritimo coming? :confused:

GB - Can not wait to see your new project. :yeah:

David

[David Hajj]

Nothing compaired to Eddieh's work but they give a fair representation.

David

[David Hajj]

I ran the Scarab for the first time after rebuild from painting. it ran perfect. The wind was about 15 mph with gusts and rough water but she ran great. The pics are not very good. I forgot to check the quality, had it set to low. :doh: I also was running the boat and taking the pics, no easy task. The new lipo's work well, went easy breaking them in first run. Timed run of 12.5 mins on the water, 5.47 mins throttle time. Voltage after run 3.803 per cell at 90 degrees with motor shaft at 123 degrees. Hit full throttle two times, caught a cross wave and barrel rolled the boat. Landed perfect right side up and kept going. Complete luck and a heart stopper. Just the drivers got soaked, poor guys I should treat the better.

The Plettenberg 370 has plenty of power, no more is needed unless you wanted to just race. In current trim it runs around 52 or so and to much for scale water conditions of true offshore running. I hope to get some video if Harry can help. (HINT :) )

Thank you to everyone whom has helped me with this project. I could not have done it with out the help. She is truly stunning to watch run at speed across the waves. :yeah:

David

[Peter Zicha]

David watching a video would be cool , your pictures are nicer than you give your self credit . I hooked up the water cooling on mine today while I watched out the window as it snowed :( :( . the water you are running your boat in looks good enough to jump in and do the nestea plunge

[David Hajj]

Some asked to see the interior, here it is.

David

[eddieh]

david the boat looks like it is a 1:1 scale!! very nice I like the nice neat layout inside too, I have done similar with my 1/8th... your drivers look excellent, your being too modest LOL... great job, and I second that video request!! :wave:

[David Hajj]

Thanks Eddieh, if the weather will come around this weekend maybe Harry and I can get together to run and get some video. He is pretty darn good with a camera. Maybe we can get some video of his Apache and the Scarab together.

I am cutting new closed cell foam for the arm fillers in the sleeves. They had open cell in them and my guys stay wet for ever. I will take apart a shirt and make patterns for new jackets in a different color, out of quick dry material. I found a cheap pair of running shorts on sale, $5.00 for material. :eek: I also made new shields for their helmets out of thin black plastic sheet. The originals were some acetate clear junk that the sun warped, not good.

David :)

[eddieh]

That makes very nice 1/8th drivers..... they are resin on the outside and foam on the inside, LOL... they love getting wet... just in case you lose any...:yeah:

[David Hajj]

I will use your drivers for the Hydro for sure, such great work.

David

[Old Sloppy]

your drivers look excellent, your being too modest LOL... great job,

I have seen that boat in person and it looks better than in the pictures.

David has a way of understating his results.

That boat could win a Concours award.

Harry