Go Back  RCU Forums > RC Airplanes > Giant Scale Aircraft - 3D & Aerobatic
Reload this Page >

Bridi Big Kaos engine choices???

Notices
Giant Scale Aircraft - 3D & Aerobatic Discuss all your 3D & Aerobatic giant scale airplanes right here!

Bridi Big Kaos engine choices???

Old 04-09-2012, 04:13 PM
  #1  
Scota4570
Senior Member
Thread Starter
 
Join Date: Jan 2009
Location: Salinas, CA
Posts: 841
Likes: 0
Received 0 Likes on 0 Posts
Default Bridi Big Kaos engine choices???

I am about to start a Bridi Big Kaos kit,
http://www.bridiairplanes.com/hangar/bigchaos.html
They are suggesting 90-180 glow. IMHO they tend to be conservative on engines. The wing area is 1140. The weight is suggested at "11-Lbs w/o the engine.

I have a conversion engine just like the one linked next,
http://tech.flygsw.org/OPS.htm
It weighs about 2000 grams or 4-pounds with the muffler. It produces 4 HP at 8300 rps (18x10 prop at 8300)

I looked up some engine specs:
OS AX120 produces 3.1hp for 870 gm
OS BGX 3500 4.04 hp / 1340 gm
ST G2300 3.7 hp/ 1077
Moki 210 3.3hp/ 1275
Moki G180 3 / 1200

I want as much power as the airframe can handle. I also do not want to use an engine that is so heavy as to destroy the handling qualities. I am not interested in glow engines, only gas need apply. From what I am gathering I will be increasing the all up weight by about a pound, all else remaining equal, IF I use my OPS.

Anyone have any help they can give me on the suitablility of my OPS engine?
Old 04-10-2012, 04:23 AM
  #2  
grant118
My Feedback: (26)
 
Join Date: May 2003
Location: Mount Pleasant, SC
Posts: 332
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Bridi Big Kaos engine choices???

That looks like a great engine. I have a RC Showcase 180 gas engine that is similar and would work very nicely. The RCS may be a littly bit lighter though. Look at the spec for the RCs and it should give you an idea of the thrust/prop to use and you could check the thrust to weight ratio for your set up. The Moki would give you the most power but I know you want to stay with gas. Keep posting your build picks.
chris
Old 04-10-2012, 08:43 AM
  #3  
Zippi
My Feedback: (10)
 
Zippi's Avatar
 
Join Date: Jun 2004
Location: Evansville, IN
Posts: 4,977
Likes: 0
Received 1 Like on 1 Post
Default RE: Bridi Big Kaos engine choices???

OS AX120 spinning a 17X6 prop.
Old 04-10-2012, 08:56 AM
  #4  
Sport_Pilot
 
Sport_Pilot's Avatar
 
Join Date: Jan 2002
Location: Acworth, GA
Posts: 16,916
Likes: 0
Received 1 Like on 1 Post
Default RE: Bridi Big Kaos engine choices???

I think the OS FX 160 is the most common engine used and should be used for comparison.
Old 04-10-2012, 07:52 PM
  #5  
Scota4570
Senior Member
Thread Starter
 
Join Date: Jan 2009
Location: Salinas, CA
Posts: 841
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Bridi Big Kaos engine choices???

OS 160 SPECIFICATIONS

Displacement: 1.60 cu in (26 cc)
Bore: 1.32 in (33.6 mm)
Stroke: 1.16 in (29.6 mm)
Practical rpm: 1,800-10,000
Output: 3.7 hp @ 9,000 rpm
Engine weight: 32.6 oz (925 g)
Muffler weight: 9.7 oz (275 g)

That would make my engine 1.7-pounds heavier. Would 1.7-pounds turn a nice flying aiplane, of this size, into a pig?

Old 04-11-2012, 04:09 AM
  #6  
Sport_Pilot
 
Sport_Pilot's Avatar
 
Join Date: Jan 2002
Location: Acworth, GA
Posts: 16,916
Likes: 0
Received 1 Like on 1 Post
Default RE: Bridi Big Kaos engine choices???

I doubt that would be significant on this sized plane, but maybe if you could shorten the nose you could remove weight from the tail. I would ask this question on the classic pattern forum, I am sure sombody there has one.
Old 04-11-2012, 08:53 AM
  #7  
MetallicaJunkie
 
MetallicaJunkie's Avatar
 
Join Date: Sep 2006
Location: Donna, TX
Posts: 5,464
Received 1 Like on 1 Post
Default RE: Bridi Big Kaos engine choices???

do you have pics... id love to see a giant Kaos.... a buddy of mine keeps saying he wants to blow up a kaos to 50cc size
Old 04-11-2012, 04:00 PM
  #8  
Scota4570
Senior Member
Thread Starter
 
Join Date: Jan 2009
Location: Salinas, CA
Posts: 841
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Bridi Big Kaos engine choices???


ORIGINAL: MetallicaJunkie

do you have pics... id love to see a giant Kaos.... a buddy of mine keeps saying he wants to blow up a kaos to 50cc size
The Bridi Big Bee has a simmilar wing as the Kaos. The airplane is larger. A 50cc, is about perfect. I would lighten the fuse a bit, it is lite ply and a little beefier than necessary IMHO. I have one and like it very much. The BME 50 has been the best match so far. I am now flying it with a 65cc conversion. I first flew it with a Zenoah 41cc conversion. The plans suggest a G-38. Flip the fuse over and make a low wing Big Bee and I think you will be close to your 50cc Kaos.
Old 04-11-2012, 04:01 PM
  #9  
Scota4570
Senior Member
Thread Starter
 
Join Date: Jan 2009
Location: Salinas, CA
Posts: 841
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Bridi Big Kaos engine choices???

nm
Old 04-11-2012, 05:36 PM
  #10  
Texastbird
 
Texastbird's Avatar
 
Join Date: Jul 2002
Location: La Porte, TX
Posts: 1,217
Likes: 0
Received 2 Likes on 2 Posts
Default RE: Bridi Big Kaos engine choices???

Big Bee has a 96" wing compared to 80" on the Kaos.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

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

Copyright © 2023 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.