R/C airboats

microflitedude wrote:

mitchg95 wrote:what is "coFg"? center of fricken gravity?

CofG = Center of Gravity.

ok, i got confused because of the "f" in there. cg is how far back on swamp boats?

ok cg is 33% back from the "transom"
what is the the transom?

The Transom is the flat far back end of the boat, usually where the engine is mounted.

microflitedude wrote:The Transom is the flat far back end of the boat, usually where the engine is mounted.

oh ok, with a 12'' model boat and a peewee how close to the back should i mount the motor?

I'm not sure, I haven't worked with small boats. Just really big sailboats.

microflitedude wrote:I'm not sure, I haven't worked with small boats. Just really big sailboats.

yeah, im thinking maybe 2-3'' from the back?

Funny "land lubber" discussion above.

That's OK boys ya' gotta learn somewhere. Recommend a nautical dictionary.

dinsdale wrote:Go and have a look over here. http://www.rcairboats.net/phpBB/viewforum.php?f=6&sid=4839e0c268c3e5a5bdcdab245c6d1301 There really is a lot more to it than one would think at first glance.

i just joined there site, now i will be able to learn more on rc boats

mitchg95 wrote:what is "coFg"? center of fricken gravity?

Ouch!!

Do treat everyone helping you like that? I think you'll see that I used the standard abbreviation for centre of gravity - CofG, not coFg.

mitchg95 wrote:
oh ok, with a 12'' model boat and a peewee how close to the back should i mount the motor?

Any more and you'll have someone else building it for you. 33% is 1/3 or one third. You have to position all your stuff to have the CofG (correct abbreviation) about 33% in from the stern, or 66% back from the bow. If you don't understand some words, Google is your friend.

mitchg95 wrote:
i just joined there site, now i will be able to learn more on rc boats

You're not a big reader either, are you. The site is RC Airboat World. You were asking questions about building an airboat.

You are shaping up as a particularly rude individual. If you didn't want help, why did you ask?

Dins:

For your information Mitch is a teenager in Colorado that we've been helping along with his various ideas for about a year. Personally I believe you are being harsh with him because he used a slang word that most of us find unacceptable too. I know Mitch well enough through PM's to know that he won't be using "friggen" again.

FYI, Colorado is mountainous, land-locked, high altitude state more famous for skiing than boating. Denver, Colorado is billed as "The Mile-High City"

E'nuf said.

SuperDave wrote:Dins:

For your information Mitch is a teenager in Colorado that we've been helping along with his various ideas for about a year now. Personally I believe you are being harsh with him because he used a slang word that most of us find unacceptable too. I know Mitch well enough through PM's to know that he won't be using "friggen" again.

FYI, Colorado is mountainous, land-locked, high altitude state more famous for skiing than boating. Denver, Colorado is billed as "The Mile-High City"

E'nuf said.

I spent a month in Colorado - his manners are still abominable.

"Fricken" doesn't worry me at all. His attitude towards someone trying help him is what I'm incensed about. As an airboat builder for about 15 years I have some knowledge which he asked for. As a result his bad attitude was given back to me.

A genuine apology is due.

I seen the word "fricken",,but no bad attitude twoards you Dinsdale. I reread all of that several times and didn't see any bad attitude in the posts.

Dinsdale, i did not mean to be rude. im sorry if you think i was, what i meant on my comment on CoFg was just trying to be funny i was not trying to be rude

mitchg95 wrote:Dinsdale, i did not mean to be rude. im sorry if you think i was, what i meant on my comment on CoFg was just trying to be funny i was not trying to be rude

Apology accepted.

dinsdale wrote:

mitchg95 wrote:Dinsdale, i did not mean to be rude. im sorry if you think i was, what i meant on my comment on CoFg was just trying to be funny i was not trying to be rude

Apology accepted.

thanks man

Here is my Dumas Lil Swamp Buggy. Custom built .049, fed off of a Sullivan 1oz tank. Cox 5x3x3 prop. Traxxas 27mhz radio set with standard servos. I think it's too heavy though; I will weigh it when I find the scale.

I am going to use one of those rectangular heat sinks used on some of the Cox cars.

Just a few thoughts Matt, hope you don't mind.

If your fuel tank is not glued into that box, you might want to add some foam insulation on the bottom and sides, a couple rubber bands to hold it in place. It's like a big tuning fork on top of that engine mount stand. I built a box like that also on my original boat, and ended up trimming off the sides with a dremel and just having the bottom piece to support the tank.to save a bit of weight, vibration and so that spilled fuel or water didn't weight that box down.

Some grease around the throttle servo horn, to keep water intrusion from seeping down the servo splined output shaft. take a good look at all of your electrical stuff that is exposed to water, make sure it cant intrude into that system anywhere. A couple of really hard turns at speed and and you might get the deck awash with water,,or if it flipps over.

You already have quite a bit of weight to the rear of the boat, which makes it harder to get "on plane",,on top of the water. You might have to give it a hearty throw across the water to get it planeing, and then keep it throttled up. The original plans just call for a 5cc tanked engine mounted to that stand back there,,and nothing else. Everyone adds a fuel tank,,I did also, you just have to keep it really simple back there. Time out your fuel tank at full sing on the dock, and set a timer, that way you dont run out of fuel out in the middle of the lake or pond. Give yourself about a 40-50-60 second "reserve" to get it back to the dock.

A tennis ball tied to fishing line on a fishing pole to be able to cast over the boat and drag it back in if it is close enough. Run the line thru the ball. Just a tennis ball, don't get tricky with some 3 pronged trebel hooks on the ball, you could flip the boat over with the hooks if you snag the engine stand up high, been there tried that,, Easy retrieval as you pull it in,,might take more than one cast to retrieve.

Thanks for the tips.

I may get a 2.4 radio set for $25. Much smaller RX. Maybe a smaller servo for the rudder? a standard seems a little big to me. I guess I should probably take the heat sink off. I built the box with very thin ply. I don't have any foam at the moment, maybe a shop rag will work.

I built a switch harness for it, which worked great while dry-fitted. Once I soldered it together, it stopped working. I need to find my multimeter.

We bought two Swamp Buggies at a Hobby Shop once. The bigger one used a .25 Magnum. The engine ran like crap in a plane. We put it in that and blasted through the water. After that the engine ran great. Guess it just needed broke in. The smaller one called for an .049. It came with an Enya .09. That one had a ton of leaks and we could never get it sealed good. It went into the water once. Then went on a shelf. They are a ton of fun.

Rolla

microflitedude wrote:Thanks for the tips.

I may get a 2.4 radio set for $25. Much smaller RX. Maybe a smaller servo for the rudder? a standard seems a little big to me. I guess I should probably take the heat sink off. I built the box with very thin ply. I don't have any foam at the moment, maybe a shop rag will work.

I built a switch harness for it, which worked great while dry-fitted. Once I soldered it together, it stopped working. I need to find my multimeter.

You might have heat soaked the switch during soldering and melted the contact stands inside. See if you can get it working smoothly again. If not, dump it and get another one. No worse feeling than seeing your boat take off on a cruise of its own desire. Airtronics makes a brutally tough switch. I have used them for years in RC panes and rugged offroad racing exclusively with no failure or glitch to this date. A chunk of party balloon sandwitched between switch cover and switch thru the hatch for waterproofing.
http://www.amainhobbies.com/product_info.php/cPath/1574_136/products_id/4099/n/Airtronics-Standard-Z-Connector-Receiver-Switch-Harness-with-Charging-Connector

When I first put mine together, I used a standard sized futaba for the rudder, a 4 cell AA pack, and a standard sized reciever from that stick radio kit I had (still do). I ran the stock 5cc tanked Babe Bee. Eventually I bored a hole in the 5cc tank and made a remote tank connection like you did to a wedge style 1 3/4 oz tank mounted in between the engine mount struts on a wooden stand I made to get the pickup point close/higher to the needle. Little did I know at the time that the tank pickup was still well below the needle. But it ran fine and would jump right up on plane after a short distance,,just setting the boat in the water.. That was the best nitro configuration for it, out of all the configurations I did to that poor little boat. It was a simple setup, fairly light, and it had plenty of run time.

I used a tank very very similar to this. I think I still have the tank somewhere. I used a piece of about 2" diameter wooden coathanger dowel and glued it to the bottom of the tank and then to the deck of the boat to get the elevation of the tank pickup higher.
http://www.ebay.com/itm/FT30-Kap-Pak-T8-1-Oz-Wedge-Fuel-Tank-NOS-/300757437082?pt=Radio_Control_Parts_Accessories&hash=item46068a4a9a#ht_858wt_1271

I would keep your standard servo for the rudder, pull the throttle setup off of engine and boat. If you need to slow the boat down, a few turns will drop the speed, once the speed is bled off enough, then you can waggle turn it back and fourth back to the shore and on to the bank at your feet. No heatsink is really needed, it will live just fine. Insulate your tank with the shop rag if that's all you have. A pusher config is pulling air past the motor for cooling, and then once you get it moving it gets a bit more cooling. My Babe Bee lived for years like that and many quarts of Cox fuel.

Would you mind if I tested it first before pulling the RC assembly off? I love throttled engines, and am more relaxed when running them vs wide open the whole time. Noise is also an issue where I live. But if it won't get up on plane then I guess I have no choice.

I switched out the servo plugs on the receiver and it worked. They were plugged in the right way, doesn't make sense. (Futaba connectors won't go in the wrong way)

It was too late though, I had already chopped up the harness again. I am now using a switch like the one you linked to. I ordered a silicone boot to waterproof it.

How/where would you put the charge lead for the RX battery? I don't want to take the screws out after every session to recharge it.

In October I'll take it to my club's float fly.