Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

YS .61 & Sig King Kobra

Reply

Old 06-07-2007, 10:58 PM
  #1  
ptulmer
Senior Member
Thread Starter
My Feedback: (5)
 
ptulmer's Avatar
 
Join Date: Apr 2003
Location: Brunswick, GA
Posts: 4,867
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default YS .61 & Sig King Kobra

I picked up a Sig King Kobra a while back with a piped YS .61 in the nose. It's never been ran. All it needed was for the servos to be installed and now that's done. It's still going to be a few weeks before I'm going to be able to fly it, but am wondering a few things.

#1, would the YS .61 w/ tuned pipe fly the KK into the "Extreme Speed" range?

#2, it didn't come with a manual for the YS. Is there a special method for break-in or anything else peculiar to this engine I should know?
ptulmer is offline  
Reply With Quote
Old 06-07-2007, 11:01 PM
  #2  
ptulmer
Senior Member
Thread Starter
My Feedback: (5)
 
ptulmer's Avatar
 
Join Date: Apr 2003
Location: Brunswick, GA
Posts: 4,867
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: YS .61 & Sig King Kobra

Oh, missed one question!

#3, what prop would you guys suggest for this combo?
ptulmer is offline  
Reply With Quote
Old 06-08-2007, 02:32 AM
  #3  
myersflyers
My Feedback: (32)
 
Join Date: Feb 2002
Location: Chicago, IL
Posts: 444
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: YS .61 & Sig King Kobra

ptulmer,
Which YS .61 do you have the AR version which has a aluminum machined head or the heavier cast head?
Both are long stroke engines design to turn lower RPM's(9-10k) on high pitched props (i.e. 12x12).
The machined head 61 runs cooler and is much lighter than the older cast head.
These engine where designed to pull the older style ( early 90's) pattern birds with authority, yet VERY QUITELY.
Though not designed for speed they can be made to run well at higher RPMs.
Keep in mind that YS engine have a number of parts, including diaphram, spring and plunger on the pump
and gaskets that require maintence. You should be prepared to change the gaskets and pump diaphram
quite regularly. I would also recommend changing the bearings to BOCA ceramics for the YS61. This will
make quite a difference if you're running high R's on this engine.

I have owned a number of YS .61s and for what you wish to accomplish here are some recommendation.
I certainly am not an engine expert and others may have even better info, but for what it's worth here my
suggestions if you want speed and are not concerned about noise.

- KEEP THE PLANE WEIGHT AROUND 8.5 lbs OR LESS
- BREAK ENGINE IN WITH THE SAME PROP YOU ARE GOING TO FLY WITH
- USE 10-15% NITRO WITH 2oz OF CASTOR ADDED TO EACH GALLON
- McCOY MC9 or OS 8 PLUGS
- PROP APC 11X8 OR A WELL BALANCED MASTER AIRSCREW 11X7.5
- HATORI or MACS PIPE for .60 class engines or an ULTRA THRUST MUFFLER
- 14" DISTANCE FROM GLOW PLUG TO TUNE PIPE HIGH POINT (Hatori or Macs)
- KEEP ENGINE MORE ON THE LEAN SIDE (don't try extracting every RPM you can get) R's around 14-14.5K

Hope this helps,
Keith
myersflyers is offline  
Reply With Quote
Old 06-08-2007, 08:39 AM
  #4  
ptulmer
Senior Member
Thread Starter
My Feedback: (5)
 
ptulmer's Avatar
 
Join Date: Apr 2003
Location: Brunswick, GA
Posts: 4,867
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: YS .61 & Sig King Kobra

Keith, that was some very unexpected info! I was expecting to hear it would wind up, but that's ok. Well, not really. Exchanging pitch for RPM means losing some thrust. But I can live with it. The head is dark grey and kinda square. I'm at work right now, but could provide some pictures later.

The strange thing is the complete lack of information on the 'net about this engine. It looks like the 61 STII, but that's a 'copter engine. To tell the truth, I haven't paid a lot of attention to the engine yet. I was working my way forward. I don't remember a pump, etc, so probably need to give it a good look-over this afternoon.
ptulmer is offline  
Reply With Quote
Old 06-10-2007, 05:24 PM
  #5  
wylieruneyjr
Member
 
Join Date: Nov 2006
Location: McClellanville, SC
Posts: 80
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: YS .61 & Sig King Kobra

It,s okay fast, but not extreme. Watch your control throws, too much is bad. If it snaps out at top of loop, lower your elevator throws. Plane likes long strokes and pipes, very good choices indeed. Recommend you dont go to high on prop pitch, can cause funny things to happen. If you try to increase speeds above what it flies normally.bad things start happening. Be happy with what it does as speed is concerned and do some diving highspeed low passes. Higher rpms and lower pitch prop good , stay below 9 pitch! Enjoy the plane. It was never real fast, just fast 100 120 mph is fast enough.
wylieruneyjr is offline  
Reply With Quote

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