Go Back  RCU Forums > RC Boats > RC Airboats
Reload this Page >

Cobra plans underway

Notices
RC Airboats Discuss R/C Airboats here!

Cobra plans underway

Old 07-04-2017, 02:39 AM
  #76  
davidmc36
 
davidmc36's Avatar
 
Join Date: Dec 2016
Posts: 31
Likes: 0
Received 0 Likes on 0 Posts
Default

Looking through some motors here I was telling you about the other day. A couple Scorpions come to mind.

Scorpion 3032-10 brushless outrunner motor

Not exactly the 3026 I have but close:

https://hobbyking.com/en_us/scorpion...___store=en_us

50 amp ESC looks a little small, I have a few of those. 80amp High Voltage or 100 ICE is overkill.

I'll keep looking for ESC.

I found two 550 cans and a couple Princess Auto generics too for the Jeep.
Old 07-06-2017, 01:39 PM
  #77  
vintageshack
Thread Starter
 
Join Date: Feb 2012
Location: Appleton, NL, CANADA
Posts: 80
Likes: 0
Received 0 Likes on 0 Posts
Default

Nice! That with a coarse pitch prop should make it go pretty good! It's been so long since I started this project, it would be nice to actually see it go!
My son is going to be excited about the jeep motors too!
Old 02-25-2018, 07:01 PM
  #78  
vintageshack
Thread Starter
 
Join Date: Feb 2012
Location: Appleton, NL, CANADA
Posts: 80
Likes: 0
Received 0 Likes on 0 Posts
Default

Just a little teaser! Got a couple gifts from davidmc36! It's still slow going but at least there's progress...
Attached Thumbnails Click image for larger version

Name:	20180225_210112.jpg
Views:	81
Size:	1.52 MB
ID:	2256131  
Old 02-26-2018, 03:25 AM
  #79  
davidmc36
 
davidmc36's Avatar
 
Join Date: Dec 2016
Posts: 31
Likes: 0
Received 0 Likes on 0 Posts
Default Video will be required!

Warm up the camera when you get that ready!
Old 02-26-2018, 03:37 AM
  #80  
vintageshack
Thread Starter
 
Join Date: Feb 2012
Location: Appleton, NL, CANADA
Posts: 80
Likes: 0
Received 0 Likes on 0 Posts
Default

Oh I'll make sure I do!! Still looking for a prop tho!
Old 02-26-2018, 03:46 PM
  #81  
davidmc36
 
davidmc36's Avatar
 
Join Date: Dec 2016
Posts: 31
Likes: 0
Received 0 Likes on 0 Posts
Default

How much room did you have for prop?
Old 02-26-2018, 07:55 PM
  #82  
vintageshack
Thread Starter
 
Join Date: Feb 2012
Location: Appleton, NL, CANADA
Posts: 80
Likes: 0
Received 0 Likes on 0 Posts
Default

I might (emphasis on might) have room for a 10 inch prop..
Old 02-28-2018, 07:16 AM
  #83  
davidmc36
 
davidmc36's Avatar
 
Join Date: Dec 2016
Posts: 31
Likes: 0
Received 0 Likes on 0 Posts
Default

I put a calander note in my phone. Will poke around when I get back south.
Old 03-03-2018, 07:33 PM
  #84  
vintageshack
Thread Starter
 
Join Date: Feb 2012
Location: Appleton, NL, CANADA
Posts: 80
Likes: 0
Received 0 Likes on 0 Posts
Default

Motor mount is done. There is a 5 degree (ish) offset and drop as per the instructions. I made one of the mounting holes slotted so I can adjust it if that is too much offset. I alodined it for a bit of corrosion protection (and to make it look nice of course) I am in the process of sourcing a propeller. The coarsest pitch 3 blade 9 inch I can find is 7, but I can also get a 9x9 2 blade. I will probably get both of these and see what works best.
Attached Thumbnails Click image for larger version

Name:	mount 1.jpg
Views:	72
Size:	718.0 KB
ID:	2256762   Click image for larger version

Name:	mount 2.jpg
Views:	56
Size:	1.34 MB
ID:	2256763   Click image for larger version

Name:	mount 3.jpg
Views:	45
Size:	1.31 MB
ID:	2256764   Click image for larger version

Name:	mount4.jpg
Views:	46
Size:	1.32 MB
ID:	2256765  

Last edited by vintageshack; 03-03-2018 at 08:51 PM. Reason: spelling
Old 03-06-2018, 03:25 PM
  #85  
davidmc36
 
davidmc36's Avatar
 
Join Date: Dec 2016
Posts: 31
Likes: 0
Received 0 Likes on 0 Posts
Default

Sounds like a couple good ones that will be just a wee bit different for adjusting what U like. 7 pitch will launch and lots of top end with the 9 inch. Probably a couple battery choices are applicable for even more prop choices.

I probably have something in an 8 inch pitch in The Tickle Trunk.

Scorpion looks good in there.

Last edited by davidmc36; 03-06-2018 at 03:27 PM.
Old 03-07-2018, 02:19 AM
  #86  
vintageshack
Thread Starter
 
Join Date: Feb 2012
Location: Appleton, NL, CANADA
Posts: 80
Likes: 0
Received 0 Likes on 0 Posts
Default

Yup, the scorpion sits there like it belongs!! I can't wait to try it out! In the meantime, here is a little sample of what I am doing with it right now.. Still very rough,, lots of touch-ups to do on it yet!
Attached Thumbnails Click image for larger version

Name:	20180307_043854.jpg
Views:	50
Size:	1.35 MB
ID:	2257952  
Old 03-07-2018, 03:39 AM
  #87  
davidmc36
 
davidmc36's Avatar
 
Join Date: Dec 2016
Posts: 31
Likes: 0
Received 0 Likes on 0 Posts
Default

Like some of the old War Planes, cool.
Old 03-18-2018, 02:59 PM
  #88  
davidmc36
 
davidmc36's Avatar
 
Join Date: Dec 2016
Posts: 31
Likes: 0
Received 0 Likes on 0 Posts
Default

You probably have better props than what I found. 9X7.5E was the only thing that looked interesting. Not a lot of high pitch used for planes unless you are in to pylon or something.

That three blade to get a feel for it then run the 9x9 and see what it will do.
Old 08-10-2019, 02:34 AM
  #89  
vintageshack
Thread Starter
 
Join Date: Feb 2012
Location: Appleton, NL, CANADA
Posts: 80
Likes: 0
Received 0 Likes on 0 Posts
Default

So, after much delay and gathering of dust, I've finally decided to pull out the cobra (no pun intended) and get it finished! I have the motor and ESC hooked up, and I am hoping when I get home to have it in the water! I still need to finalize a battery, but for testing purposes, a 12v lithium ion drill battery will do.. Here is a short video of the motor test on 12v.
Old 08-10-2019, 03:51 AM
  #90  
davidmc36
 
davidmc36's Avatar
 
Join Date: Dec 2016
Posts: 31
Likes: 0
Received 0 Likes on 0 Posts
Default

Just be careful to keep part throttle tests on bench to a minimum. That's when the ESC will get the hottest. Full bore is just passing power to motor. Part throttle modulates and extra power is bled off as heat. Needs air flow.

Can't wait to see it go!
Old 08-10-2019, 11:48 PM
  #91  
vintageshack
Thread Starter
 
Join Date: Feb 2012
Location: Appleton, NL, CANADA
Posts: 80
Likes: 0
Received 0 Likes on 0 Posts
Default

Good to know! I shall keep them to a minimum. While we are talking heat and airflow, do you think I will need to make a vent for the esc? It is in the section just behind the motor.. some air will get pass the motor, but if I make a vent on the side (maybe similar look to a cowl flap) the airflow would be much better.. Just wondering if you think it would be necessary?
Old 08-11-2019, 01:16 AM
  #92  
davidmc36
 
davidmc36's Avatar
 
Join Date: Dec 2016
Posts: 31
Likes: 0
Received 0 Likes on 0 Posts
Default

I think the blurb says 5 mph airflow is required to run up to max current spec. Even a small scoop directed at the heat sink will cool it a lot. It doesn't take much to equal 5mph in free air with a small ram air duct.

How much goes past motor? What's the cross section look like?
Old 08-11-2019, 10:26 AM
  #93  
Got RPM
 
Got RPM's Avatar
 
Join Date: Nov 2006
Location: AZ
Posts: 774
Likes: 0
Received 5 Likes on 5 Posts
Cool

I run a Castle ICE100 air controller sealed inside one of my airboats, it gets warm but hasnít overheated. But then, I am not propping for a high amp power level. The problem with air vents is that when the boat flips (and it eventually will if it has any speed) all the electronics get soaked. They may work again when they dry out, or they may not.

I run a very similar motor in one airboat, a Scorpion 3026/1090 on 4S. It runs mid-30s with an APC 8x4 prop averaging 40 amps, but becomes unstable at higher speeds with a 9x4.5 due to the hull design. I suspect that your stated prop choices will not work very well, for several reasons. First, the amp draw will be high and the controller might overheat. You may not want to run a coarse-pitched prop on most airboats, they will stall at 0 speed and the thrust will be very little. The Cobra is a bit tough to plane off anyway due to the prop location and the hull design. Best to not go much more than 50% of the diameter at first. You need thrust to move the boat, not theoretical mph.


Old 08-14-2019, 09:16 AM
  #94  
vintageshack
Thread Starter
 
Join Date: Feb 2012
Location: Appleton, NL, CANADA
Posts: 80
Likes: 0
Received 0 Likes on 0 Posts
Default

I have a 9x6 on it now, I don't plan on running the bag off it right away, but I may pick up a couple finer pitch props for later. I will leave the venting for now, but I will keep a close eye on the temps. Nice boat btw!
Old 08-15-2019, 05:43 AM
  #95  
davidmc36
 
davidmc36's Avatar
 
Join Date: Dec 2016
Posts: 31
Likes: 0
Received 0 Likes on 0 Posts
Default

What r u running for radio? Do u have telemetry to hook up temp probe?

Or what about the ESC. You have the little interface to download the data after a run?
Old 08-16-2019, 10:38 AM
  #96  
vintageshack
Thread Starter
 
Join Date: Feb 2012
Location: Appleton, NL, CANADA
Posts: 80
Likes: 0
Received 0 Likes on 0 Posts
Default

I'm running a pretty basic Flysky GT2B 3 ch radio.. so no temp probe hookup.. I think the interface hookup will help for sure tho! I would be home by now, but I came to work late so I have to make up some time.. Tuesday tho! I'll have it in the water then!! ... After catching up on household projects... Well, maybe a quick run to the lake first!
Old 08-22-2019, 06:06 AM
  #97  
vintageshack
Thread Starter
 
Join Date: Feb 2012
Location: Appleton, NL, CANADA
Posts: 80
Likes: 0
Received 0 Likes on 0 Posts
Default




I just realised I don't have any completed pics of the boat on this thread yet! Anyways here are a few I took last night.. I haven't had a chance to test it in the lake yet.. Did a quick test in the kids pool, noticed I didn't seal up the skeg! (oops) good thing I found out before a proper lake test! I may have to mess with center of gravity a bit.. I think battery placement should be enough to balance it out
Old 08-22-2019, 06:21 AM
  #98  
Got RPM
 
Got RPM's Avatar
 
Join Date: Nov 2006
Location: AZ
Posts: 774
Likes: 0
Received 5 Likes on 5 Posts
Cool

Love the pics. Where were you planning to set your CG? Is there an exit for the cooling air from the motor nacelle?

Don’t forget to tape the hatch seams.

.

Last edited by Got RPM; 08-22-2019 at 06:23 AM.
Old 08-22-2019, 07:11 AM
  #99  
vintageshack
Thread Starter
 
Join Date: Feb 2012
Location: Appleton, NL, CANADA
Posts: 80
Likes: 0
Received 0 Likes on 0 Posts
Default

The C of G according to the plans should be just behind the split in the fuselage just ahead of the cockpit.. I will try to get it as close to that as possible and go from there.. I don't have any vents yet.. I won't be doing any really long runs just yet.
Old 08-22-2019, 02:30 PM
  #100  
davidmc36
 
davidmc36's Avatar
 
Join Date: Dec 2016
Posts: 31
Likes: 0
Received 0 Likes on 0 Posts
Default

Looking real nice. Don't forget the video when you get floating.

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.