Cox Engines Forum
You are not logged in! Please login or register! Guests are limited to posting in the "General Questions (Guest Posting Allowed)" section only. Becoming a member is fast, easy and FREE!


Log in

I forgot my password

Search
 
 

Display results as :
 


Rechercher Advanced Search

Cox Engine of The Month
July-2017
Mark Boesen's

Nice original Babe Bee from a Super Cub 105, late fifties.



PAST WINNERS
CEF Traveling Engine

Tach Race 2017 Updates
Ready for Tach Race 2017?
Profile Scale Reed Speed
Gallery


Win This Engine!
The Traveling Prop
World of Aviation

Cox 049 powered race boat

View previous topic View next topic Go down

Cox 049 powered race boat

Post  OVERLORD on Thu Oct 23, 2014 12:06 pm

This video was posted a few years ago by Brad I think, on RC Universe. It's a Black Widow powered boat that goes quite well. At the end, the boat turns over and the pilot gives a detailed and technical explanation of what happened exactly.



Some more pictures and info can be found here:

http://www.rcuniverse.com/forum/speed-rc-nitro-boats-117/8498373-1-2a-size-dumas-boat-club-13.html#post10369573

Lieven
avatar
OVERLORD
Platinum Member
Platinum Member

Posts : 1134
Join date : 2013-03-19
Age : 51
Location : Normandy, France

View user profile

Back to top Go down

Cox 049 powered race boat

Post  Davenz13 on Thu Oct 23, 2014 4:14 pm

The explanation may not have been in English but it wasn’t hard to translate lol!

My brother was involved in speedway for about forty years, first as a rider, then helping in international meetings. He often recounts how he found it quite funny to hear Russians Poles Czechs Danes etc gesturing and talking in their native language and then hurling the item in their hand towards the bin finishing with that universal word that begins with f understood the world over as “No longer serviceable”.

I hope I was able to present that in an acceptable way.
avatar
Davenz13
Gold Member
Gold Member

Posts : 249
Join date : 2013-11-28
Age : 61
Location : Palmerston North, New Zealand

View user profile

Back to top Go down

Re: Cox 049 powered race boat

Post  dckrsn on Thu Oct 23, 2014 4:20 pm

I thought your explanation was both acceptable and succinct Dave.

Potty mouth Bob.lol!
avatar
dckrsn
Diamond Member
Diamond Member

Posts : 1738
Join date : 2010-10-21
Age : 64
Location : Long Island, NY USA Earth

View user profile

Back to top Go down

Re: Cox 049 powered race boat

Post  1/2A Nut on Fri Oct 24, 2014 1:38 am

Jim Walker 1/2A Hydro

http://www.americanjuniorclassics.com/movies/Boats.wmv



The Famous Jim Walker starting the Miss Thritway and a run on the pond. Clapping
avatar
1/2A Nut
Platinum Member
Platinum Member

Posts : 1107
Join date : 2013-10-20
Age : 53
Location : Texas

View user profile

Back to top Go down

Re: Cox 049 powered race boat

Post  1/2A Nut on Fri Oct 24, 2014 2:05 am

http://www.dumasproducts.com/product_info.php?cPath=39_80&products_id=444



For those wanting to try a 1/2A boat.
avatar
1/2A Nut
Platinum Member
Platinum Member

Posts : 1107
Join date : 2013-10-20
Age : 53
Location : Texas

View user profile

Back to top Go down

Re: Cox 049 powered race boat

Post  OVERLORD on Fri Oct 24, 2014 2:21 am

The German boat has a flexible drive shaft. Looking a the prop, which has an M4 thread, the flex drive must be 1/8" diameter. It seems that it is not supported much by a brass tube, except maybe where it goes through the hull. Isn't there any risk of wobble? Or is the 1/8" flexible drive thick enough to remain in place. What if you would use a .098 (2,5mm) flex drive?


Last edited by OVERLORD on Fri Oct 24, 2014 3:12 am; edited 1 time in total (Reason for editing : correction)
avatar
OVERLORD
Platinum Member
Platinum Member

Posts : 1134
Join date : 2013-03-19
Age : 51
Location : Normandy, France

View user profile

Back to top Go down

Re: Cox 049 powered race boat

Post  1/2A Nut on Fri Oct 24, 2014 3:36 am

Yes the reality if used with even a TD engine a 2.5mm flex drive is enough to do the job. You could use wire drive too as an option. I prefer no drag straight drive shaft longer than what dumas sells to minimize the angle of attack.
2mm to 3mm or 1/8th in should hold up.

You can use teflon tube to protect the cable with some brass stock to protect the teflon and reduce vibrations / wobble.
avatar
1/2A Nut
Platinum Member
Platinum Member

Posts : 1107
Join date : 2013-10-20
Age : 53
Location : Texas

View user profile

Back to top Go down

Re: Cox 049 powered race boat

Post  roddie on Fri Oct 24, 2014 6:00 am

I had seen that vid before.. and marveled at it! There aren't many Cox powered "submerged-drive" boat vids out there. I've had an outrigger in the works for a while.. Shocked .. I have a similar Dumas kit to the one shown above. I'm trying to come up with a transom-design that allows for adjusting the height of the drive. I'm leaning toward a vertically-slotted transom.. with a guide-plate for the output shaft-tube, that can be raised/lowered. This is an important aspect for tuning the drive/hull. Flex drive cables are nice.. but if you make your own; you need to note the direction of the "twist" in the cable, so it doesn't "unravel" when loaded.
avatar
roddie
Top Poster
Top Poster

Posts : 4847
Join date : 2013-07-17
Age : 57
Location : N. Smithfield, Rhode Island

View user profile http://www.stilburnin.com

Back to top Go down

Re: Cox 049 powered race boat

Post  1/2A Nut on Fri Oct 24, 2014 7:32 am

Just a quick note - as about to leave to the office for the day the hydro is low lying by design and submits itself to more water tension the prop runs on the hub here is the likely on plane water line when not hoping over water ripples. Its light big plus and hops level when it does. Would have been faster if the rudder was reshaped as shown the rooster tail lets you know the prop is airing out a blade.


avatar
1/2A Nut
Platinum Member
Platinum Member

Posts : 1107
Join date : 2013-10-20
Age : 53
Location : Texas

View user profile

Back to top Go down

Re: Cox 049 powered race boat

Post  OVERLORD on Mon Nov 10, 2014 10:33 am

Interesting information, thanks guys. When reading different building threads of outriggers and other hull-shaped race boats, they are all finished with resin and sometimes also with fibreglass. In case of 049 driven boats, would iron-on covering do the job?
avatar
OVERLORD
Platinum Member
Platinum Member

Posts : 1134
Join date : 2013-03-19
Age : 51
Location : Normandy, France

View user profile

Back to top Go down

Re: Cox 049 powered race boat

Post  1/2A Nut on Mon Nov 10, 2014 3:32 pm

I have used iron covering if you overlap the seams well perhaps use balsarite to make it more sticky would be helpful otherwise the golden rule is a epoxy coat final finish as boats typically use high nitro mixes. If there is anything in the water such as twigs, sticks and the like could compromise the wood.
avatar
1/2A Nut
Platinum Member
Platinum Member

Posts : 1107
Join date : 2013-10-20
Age : 53
Location : Texas

View user profile

Back to top Go down

Re: Cox 049 powered race boat

Post  ian1954 on Mon Nov 10, 2014 3:40 pm

Don't use iron on covering. It is not tough enough and will easily tear, scratch or abrade away! It will leave you with soggy balsa.

You can get very light glass cloths 18g per Sq M. That and resin with judicious sanding won't add that much weight.

Unless you can seal the balsa very well, iron on covering is not a good choice. Even then - it is not very strong.

As in the previous post - you would me suprised what any sort of float debri can do to a balsa hull!
avatar
ian1954
Diamond Member
Diamond Member

Posts : 2417
Join date : 2011-11-16
Age : 62
Location : England

View user profile

Back to top Go down

Re: Cox 049 powered race boat

Post  1/2A Nut on Mon Nov 10, 2014 4:42 pm

On a side note I only use aircraft ply for all my boats these days. Back in the day I had some micro balsa boats that held up well with monokote only because they are so light covering to scale and weight was robust. You can use spar urethane with ply construction and only epoxy the inside of the hull but epoxy is king. If you make a balsa boat you should consider glassing the bottom of the hull for RTR boats weighing more than 10oz. There is one other trick with balsa boats applying a thin sheet of plastic to protect / same stuff used for protective covers for documents.
avatar
1/2A Nut
Platinum Member
Platinum Member

Posts : 1107
Join date : 2013-10-20
Age : 53
Location : Texas

View user profile

Back to top Go down

Re: Cox 049 powered race boat

Post  anm2 on Tue Nov 11, 2014 5:16 am

ian1954 wrote:Don't use iron on covering. It is not tough enough and will easily tear, scratch or abrade away! It will leave you with soggy balsa.

You can get very light glass cloths 18g per Sq M. That and resin with judicious sanding won't add that much weight.

Unless you can seal the balsa very well, iron on covering is not a good choice. Even then - it is not very strong.

As in the previous post - you would me suprised what any sort of float debri can do to a balsa hull!

Ian, What constitutes well sealed balsa? Will standard dope applied in enough coats do the job? Thanks, Andy

anm2
Gold Member
Gold Member

Posts : 284
Join date : 2013-03-30

View user profile

Back to top Go down

Re: Cox 049 powered race boat

Post  ian1954 on Tue Nov 11, 2014 6:24 am

I would use "sanding sealer". It is dope with fillers and additives. It sands to a nice finish.

I would apply the first few coats thinly so that it can soak a little further into the balsa.

Polyurethane varnish will also work but it can be a little thick.
avatar
ian1954
Diamond Member
Diamond Member

Posts : 2417
Join date : 2011-11-16
Age : 62
Location : England

View user profile

Back to top Go down

Re: Cox 049 powered race boat

Post  Sponsored content


Sponsored content


Back to top Go down

View previous topic View next topic Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum