Same 30"cat, limited experience

[CornelP]

Hello there,
I am new here and in this field generally, so be patient with me... I am building the 30"cat and I am looking for some info on the hardware to install. As you can see in the pics, I am almost finished. I started with hand cut balsa (lasercut had a crazy price...), CA in place, epoxy on the internals. The nose was filled with pool noodles, sealed shut. To make more room, I cut two of the sections, as I will cover in fiberglass or silkspan. The very tips of the nose were carved in balsa, as I did not manage to get the right curve :unsure:.
The main idea of the final shape is: F-14 Tomcat tribute! The profile is good enough, so I will go for a long canopy, as close as possible to the plane, a couple of the signature tails and a proper paint job ( F-14D Tomcat VF-31 Tomcatters). I usually do scale models (mainly aircraft), so this will be the easy job.
The main problem is hardware: what would you recommend? This means motor, battery, esc, strut/rudder, etc. I was looking on a couple of websites for ideas, but I cannot find all the stuff in one place and with some decent prices... plus, as I live outside the US, I try to buy all in one place because of the transport fees...:smile:
To get an idea on my experience, I completed a 1/10 Baby Bootlegger (Andy's one) and converted a px-16 on RC Groups. Both are brushed motors, Nimh, Futaba and Hitec systems.

[Norman2]

Hi CornelP, I built a similar cat and use a UL-1 Brushless motor and ESC. I got
these from Offshore Electrics. Hardware is from Offshore electrics. You can find
a lot of information on 30" Cat builds in the thread titled 30" Scratch Built Cat.
Hope this helps. Attached photo. Regards
Norman2

[Jesse J]

Welcome to the forum!

This ought to be a cool build, like the tomcats too. there is a wide range of hardware, depending on how much you want to make yourself - Simon O is the master of "make my own hardware" - or you could spend over $150 on hardware if you want.

Details you will need to provide to get useful feedback are:

motor you want to run, dual/single, speeds - I assume sport
batteries you want to use
and any other set up ideas you have/ limitations economically etc. or components you want to use (i.e. is this a ground up hardware, motor/esc set up or do you already have a motor or other).

[CornelP]

Well, I was looking around a little bit, and I would be tempted by the solution that Norman2 went for (single motor). Definitely Brushless, Lipos, the strut I was looking at was this OSE http://www.offshoreelectrics.com/proddetail.php?prod=tfl-502b15, as it comes with most of the necessary fittings... I have no clear idea on what components I need for such a setup, my previous experience was threaded plastic props, universal joints...
I already made some hardware, but the strut was without bearings, just a 4mm ID aluminum tube with a Robbe flex shaft (see photo). Is there any Hardware for dummies shopping list / thread?:tongue_smilie:

[CornelP]

One more thing: budget will be around 150-200$ overall (I have the radio/servo)

[CornelP]

Ok guys, I got an idea for the home made hardware, see pics. Just a sketch for now, no dimensions, but I will come back later on with a proper drawing... I have no access to CNC or any fancy machinery, so it will be done by file, Dremel... the hard way:cursing:. Water pickup will be done as in the previous post. Still waiting for ideas on motor/ESC/batteries :help:
The hull is getting fiberglassed today, so I will have the first pics up tomorrow.

[Simon.O.]

Ok guys, I got an idea for the home made hardware, see pics. Just a sketch for now, no dimensions, but I will come back later on with a proper drawing... I have no access to CNC or any fancy machinery, so it will be done by file, Dremel... the hard way:cursing:.

For all of my builds the only power tools I use is a cordless drill and a cheap copy dremel. I do have a lot of good files and handsaws.
I have a cheap 50W soldering iron for wire work and use a butane pencil torch for the bigger brass to brass work.

Patience and time with hand tools will make some fantastic hardware.
I am no master or even a craftsman but I have time to do it and am not keen to pay for postage of gear from overseas for things that I can make myself.

[CornelP]

Well said!
My humble opinion: THIS HOBBY IS ABOUT MAKING THINGS, NOT ASSEMBLING!:)

PS: an assortment of VERY good glues helps a lot...

[CornelP]

I got a fantastic offer for a Feigao 540-10XL and I could not resist... so I have a starting point.

[Eodman]

May I ask ... and by no means am I master builder, but is the water return the only thing on that strut?

If it is - have you considered attaching it the back of one of the sponsons and eliminating a little weight also a little less more drag! If you cut your brass tube on an angle you won't need to flare the end as you have!

[CornelP]

Thought about it... will consider that. The flaring was a suggestion from somebody else, based on the fact it is placed in the spray.

[CornelP]

Got some of the materials today. Will start fabricating the hardware... I also got a couple of TRex 4/7mm bearings. Is it worth installing them on the strut, instead of the brass bearing?

[CornelP]

First pic after a polyester primer/filler... This will get sanded down almost to the fiber layer... it's a nightmare, but worth it:biggrin:
Canopy is on its way, had to blow up measurements from a Hasegawa kit I finished some time ago, so it should turn up quite accurate. I HATE carving in foam...

[Eodman]

This going to be one nice looking cat when you're done! Wish I had the patience to scratch build!!!!!

[CornelP]

Well, put it this way: no patience - minimum 200$ for a beautiful hull (in Europe); patience: 25$ to this stage...

[CornelP]

First glance at the canopy. It looks small, but it is ok with the scale of the build. It will make a better impression with the anti glare paining around and the vertical fins...:bounce: I also found the paint scheme... and name: VF-101 Grim Reaper:rockon2:

[CornelP]

Parts are almost ready, just have to send the dwg to the lathe guy... I will go for a 2mm wire drive (perhaps too big, but easier to manufacture).
I also got a deal on some 4600 and 5000 mA 2S2P 20C and 35C Lipos, but they are all 7.4V. Can you actually put them in series?:help:

[CornelP]

Got the motor and ESC, waiting for the mechanical parts...
Motor: Feigao 540 10XL
ESC: Seaking 60A (120A burst) watercooled
Battery: 2x 2s2p 4000mAh 20C

If I keep the prop small for now (33 to 38mm), is it ok to use this ESC? I will order a bigger one at some point, but for now, am I safe?

[CornelP]

Still no answers to my questions, but I am stubborn...:tt2:
Anyway, latest progress: NEVER say you've done a good sanding job until you paint gloss black....:crying: but it will be a good base for the paint I am going to: bare metal finish...:buttrock:

[Norman2]

Cornelp, Looking good, I would suggest you use a heavy filling sandable primer
which will also show the imperfections. It is a long tedious job but worth it. Your setup looks ok but I would go with a 40MM prop. Make a run, check temperatures
and if too hot go to a 38MM prop as you stated, I have a UL-1 motor and esc and
run mine with an X640 Octura prop. Temps are fine and top speed I have achieved
is 45.6 MPH which I am more than happy with. Do not get discouraged. Regards
Norman
PS I run 2S1P 25C 5000 MAH Lipos

[CornelP]

For now I can only go on carbon filled plastic props, as there is no Octura dealer around here... and shipping for a couple of props is around 40$. Once I refine this enough, will order some and upgrade...

Cornel

[Norman2]

CornelP, Carbon Filled props are fine just do not go over 40MM Regards
Norman

[CornelP]

One more question: there are a couple of posts about motor timing. My Seaking ESC has 0 as default. Any point in playing with that? I would rather not...

[CornelP]

Sorry, looked in the manual: 15 as default and a cell cutoff of 3.2V

[CornelP]

Finally getting an idea of this build!! Still on the to do list: internals, canopy (silver), vertical tails and clear coat allover...

[CornelP]

Rudder is ready, just need to adjust lengths when I get the parts for the strut. What do you suggest: behind the prop or offset?

[CornelP]

Rudder/strut mounted! Still waiting for the lathe guy with the linkages...
How deep should the rudder be? The pic is way out of focus, but you can get an idea.:help:

[Rumdog]

Looking sweeeeet! I like the theme!

[CornelP]

More of the insides ready. I had to do surgery and make a hump for the steering arms... later realized I could have done the F14 beaver tail...:doh: Maybe next time...
I just love the shine of this acrylic lacquer (dual component automotive, tough but flexible when dry...)

[Jesse J]

Rockin build, are you gonna put tail fins on? I like I like!

[CornelP]

Just waiting for the spray filler to harden... and find a safe way to mount them in a removable way. ;)

[CornelP]

THERE SHE IS...:banana: still needs a clear coat on the wings and the custom grip reaper decal and the hardware (will be in tomorrow :biggrin:)
I sandwiched the hull between a piece of ply and one aluminum, fixed 2mm bolts and inserted in the wings 2 pieces of Al tubing (tight fit). They are solid enough for cruising but easy enough to remove for transport.

[CornelP]

Got the wire drive parts today :banana:.Wire is glued with Loctite 648 (extra strength). Will assemble and test in the next couple of hours...

[CornelP]

And parts installed. I drilled a small access hole for oiling, should be useful...

[Simon.O.]

And parts installed. I drilled a small access hole for oiling, should be useful...

Interesting idea. I see your shaft has the nose cone fitted. This will mean the stut has to be removed to remove the shaft. Do I see this right ??

I have looked at that idea before, the nose bullet will preven the tail shaft being lost in the event of a wire fail.
I went the other way and have a nose bullet with a recessed grubscrew that grips the 062 wire. If I blow a wire then I keep the tail shaft and prop.

I can also pull my shafts for cleaning and relubing very quickly.

[CornelP]

Yes, you are right, unfortunately.... I did not see this until I fixed the stuffing tube... without it, you disconnect motor coupler, slide it back on the wire, lift e voila... but not anymore. I am now thinking to upgrade the shaft fixing with an M5 (more solid) and an easier to remove nut.
I will probably look into your idea, it makes more sense.
Anyway, the lathe guy sent me 4 sets instead of one... he must have been bored on the job :), but that is no major problem.

[Simon.O.]

Yes, you are right, unfortunately.... I did not see this until I fixed the stuffing tube... without it, you disconnect motor coupler, slide it back on the wire, lift e voila... but not anymore. I am now thinking to upgrade the shaft fixing with an M5 (more solid) and an easier to remove nut.
I will probably look into your idea, it makes more sense.
Anyway, the lathe guy sent me 4 sets instead of one... he must have been bored on the job :), but that is no major problem.

Dont get me wrong there is nothing wrong with the setup you have. When I get a lathe I will be machining that type of shaft.
All you need are two things.
1. Scribe marks on the strut once the best position is found
2. A board or table to ensure that the strut is set correctly prior to a days running.

I do this anyway.

If you have more questions on wire drives and tail shafts and do not wish to clutter a fine build thread then please PM me, I am always happy to help.

[thegreat1]

cornelp were you in 31? im in vfa-86. 31 makes me laugh now because they are the tomcatters but they fly rhinos

[CornelP]

@ thegreat1: OH HOW I WISH I WAS.... not even the right continent, sorry...
But I know what you mean... that's a pic I did for a pal:laugh:

[CornelP]

Ok, back from holidays, got the new ESC. The Seaking 70A could only move the motor for about 5 sec, then it stopped. I found a Himodel 125A for a very good price, modified it for watercooling and waterproofed with acompound called PLASTIK70, a PCB protection spray. Should be able to get what I want: maiden voyage!!!
One more thing on the list: a new radio... the Futaba I was counting to use was shorted last week... kids with wet hands on the beach...:cursing:
Anyone used the Spektrum DX5E?

[CornelP]

Just did the first wet test (bathtub...). It floats ok (2400 grams fully loaded), no leaks.
Did the mistake to try full throttle... lucky for me I was in the kids' bathroom... one wall got soaked. It was a 45mm CF prop.
This week i definitely have to take her out...

[CornelP]

Tested it today... The glued connection wire/strut failed, just as it was getting up... will retest asap...

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

[CornelP]

Finally got to run it today... 40-50kph, quite slow as I was afraid to crash:unsure:
I am still an absolute beginner in controlling these things...
Need a bigger rudder for sure, but for the rest, the ride was smooth...:banana:
Setup is Feigao 10XL, Hitec125A ESC watercooled, 4s Lipo.

http://www.youtube.com/watch?v=vK5_6PxiDnU

[Karfrik]

nice to see it flying above the water!!!.............congratulations!!,.........Al bert/karfrik

[CornelP]

Thanks a lot, it was a fun day, ran the EWT, Bootlegger and cat, all performing better than I thought... especially the cat. I know I can get more of this hull, maybe a 45mm prop (ran it on 43ish) and 5S or 6S instead of 4S2P... the esc can take it no problem. Everything was barely warm after 5min, so the Feigao cooling did its job, as well as the brass one I did on the esc.

[Simon.O.]

Finally got to run it today... 40-50kph,
That speed looks nice for that size pond
quite slow as I was afraid to crash:
Being cautious is good, rebuild a hull is bad
I am still an absolute beginner in controlling these things...
You are learning faster than I did.:thumbup1:
Need a bigger rudder for sure,
I am not so sure you need a bigger rudder at all,


Cornel.
The rudder on my Cat is quite small, It is less than 1 prop dia below the prop which is a common guideline. Mine will change direction like a pinball at anything other than wot.
Your steering issue could be one of a few things and my main suspects are.

1. Rudder too large
2. Too much throw on the rudder from servo to the rudder. 30deg each way is lots.
3. Too much steering input from the driver.

I have a very basic Hitec FM pistol handset but I can alter the steering rate/throw with a thumb wheel. I use this to adjust the "sensitivity" of the steering of my boats.

Have another look at you whole steering setup and if you want to put up a few pics of the steering end of the boat and I am sure there will be some positive and helpful comments.

You have done well so far. I bet you are well happy with that !!:banana:

[CornelP]

Ok, here is the new rudder setup. A lot fore solid than the first version... Still need to make some space for the prop...
Anyway, take a look at the size, which one would you recommend in the last pic? Both are 1mm stainless steel.
Base for this rudder is a Graupner rudder, and it seems slightly wobbly... that is it will have a 1 degree deflection... on both axis... probably a washer will cure it, but is this normal?

:help::help::help:

PS the biggest problem I had was that in a straight line WOT I had to correct with 30% rudder to keep it straight. Somebody also suggested the servo is not strong enough...

[CornelP]

Finally got a decent run out of this hull...:rockon2:
No radar today, but a number of calibrated eyes on the pond suggested top 70s (kph). I will confirm next week, if we have a radar... This is a run on 6S, with a 45K prop, perfect combination... the only thing that got hot was the coupler and shaft, as the power was too much for my homemade ones... lost one prop and reconnected coupler 3 times. Once I settled everything, it ran stable until depletion of batteries... around 6min in total (2x3S 4200 20C series)

http://www.youtube.com/watch?v=S0Keo1CsoEU

[norbique]

Very nice cat Cornel! Good job! The wire drive is nice too. I like it a lot. I just watched the videos, and I think you should get a GPS unit to confirm speed.
I'm building a slightly bigger cat which I want to power with two motors. It came to my mind not to bother with right and left handed flex shafts, but make it a wire drive, but dropped the idea cause I haven't seen one in action until now. Now started thinking of it again. So I'm learning from you ;) Keep on!
Norbert

[CornelP]

Ok, after the "powerflip" last week (WOT, a bit windy, batteries too far back), it flew 5-6m at an 'altitude' of about 1m, I had to redo the strut, rudder mount and drive...

So this time I went a bit heavier: the aluminum angle is 3mm thick, the rudder mount is about 5mm. Total weight 170g, so i had to move the batteries 5mm further up front to get to 30%.
The wire is now glued with Loctite and fixed with 2 x 3mm blind nuts.

Should be solid enough... next flip will probably break the transom (although I also added some more ply...):bounce:

[Karfrik]

I believe you are gonna have to start taking flying lessons.....:thumbup1:.Please take video of your next launch.....:cool:,....Albert

[CornelP]

You just tell Houston to be on standby.... ;)

[Karfrik]

Ok!!!...just don`t want to hear that famous phrase said by an astronaut in the Apollo 13 and i quote: "Houston...beep...we have a problem"......lol
Please take video..........we love videos.
By the way,go to RCG and see my latest on my CenGT 775!!!,........Albert

[Jeff Wohlt]

Your ESC cooling set up is excellent. With tubes directly on the fets you are cooling much better than plates with water tubes on the edges. You may want to shrink wrap it to keep those tubes in place...unless you epoxied them on there. Is that a plate you made for the cooling tubes?

To me you can't do a better job of cooling and that is what I will be doing with some lower amp ESCs with single layers of fets.

I wonder if you could run the tubes longer to also cool the caps on the front of the ESC...they get hot and are usually the first to go.
Nice work...I love 6S set ups. Plenty of go-go juice.

[CornelP]

The cooler is actually made of two layers of copper sheet. The top one was hammered into shape, then the tubes were soldered on the ends. The whole cooler is soldered...
I will try a set of 6 x 1000mF extra caps, with a watercooler around them, will post pics when it is ready.

[CornelP]

Excellent day out! The cat was superb, I need to go to a bigger pond... We had no radar gun today, but a couple of pairs of trained uncalibrated eyes estimated it around 80kph... and I was not able to go full throttle.
Just two problems: I connected the steering with 1.5mm steel wire and it was wobbly, I have to go back to the 2mm and get a stronger servo... or reduce the rudder size. The second one was... the wire snapped on my last run. I was afraid I donated another prop to the pond gods... but it was just the wire, easy to replace.

http://www.youtube.com/watch?v=0z7ApjNxZbw

The fast runs are not on this video... :cursing: my son was sleeping on the job... next time no mp3 on the pond.

[norbique]

Hi Cornel!
What do you think why did your wire snap? Did you tun across something floating in the water?! how many cells in series did you use in the last video? And did you fit the new caps on the ESC?

[CornelP]

Well, the wire probably snapped because with the new strut the angle is a bit steeper... I should have changed the position of the tubing going through the hull. All it needs is a bit of heat on the epoxi.
I ran it on 6S, standard, the new caps were not ready... untested yet.
I need a bigger pond, to be able to reach full throttle and stay there for more than 1sec........

[CornelP]

Just because the rudder was a bit wobbly, I decided to redo the hinge... and came up with this! It should be more than enough...

[norbique]

I don't get it :confused2:

[CornelP]

The short part will have the rudder blade attached... the long one is connected to the transom.

[norbique]

OK! I got it, he he ;)

[CornelP]

New hardware is a lot more stable, it was easier to keep it straight, so more time to accelerate on this small pond. I did a nice flight ('bout 10m in lenght), but everything was ok...
See the pics, I just love the way it sits on the water... next week: bigger pond.

[Karfrik]

Where`s the hatch/canopy? at the bottom of the pond?......running nice!!!......Albert

[CornelP]

For the test runs I just got an ABS flat cover, easier to remove/check temperatures... next week will do some runs with correct canopy, wings and all. I might go on a bigger pond, where I can keep full throttle for more than 2 seconds...

[CornelP]

Guys, HELP!
Something wrong with the setup... when I increase throttle, it begins wandering left or right like crazy and stabilizes only after a couple of seconds... The rudder is solid, no real play there, just maybe the stainless rudder a bit flexible. What is a good width for a rudder? It is now about 1 inch and it somehow feels too big... maybe it is flexing. Anybody had this issue before??????