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Engine basics => Engine set up tips => Topic started by: Joe Messinger on July 23, 2006, 09:53:22 PM

Title: Super Tigre NVA
Post by: Joe Messinger on July 23, 2006, 09:53:22 PM

I've been back at c/l flying from the 60"s for only a short time (about two years) and am trying to catch up on what's what.

It seems that ST nva's are favored by many.  My question is: "What is the reason for this preference?"  I'm not "doubting" anything.  Just would like to know the particulars.

As a casual observation, it seems that the 90* bend on the end of the ST needle is more likely to cause someone to turn their knuckle(s) into the backside of a spinning prop.  Seems safer to "twist"  a knurled cap than to "turn" the "L" bend on the needle.

Thanks,

Joe

Title: Re: Super Tigre NVA
Post by: john e. holliday on July 23, 2006, 10:00:12 PM

It doesn't matter which type of needle I use.  Somehow I usually get the back side of the spinning prop.  Remember to be behind the engine when adjusting it.  DOC Holliday

Title: Re: Super Tigre NVA
Post by: Steve Helmick on July 23, 2006, 10:11:32 PM

I kinda like the K&B Universal NV assembly for sport models, tho when I crash, the needle survives, but the spraybar breaks. To get sorta serious, I much prefer the PA (aka Randy Aero) Needle Valve Assembly. It's like the ST, but has a plastic cone instead of a split collet design. The difference is very apparent when using it. The nut can be very tight, but the needle can still be turned, a good thing. You can get them from Randy or Leonard.  y1 Steve

Title: Re: Super Tigre NVA
Post by: Alan Hahn on July 23, 2006, 10:13:41 PM

I am guessing it is because a lot of the engines are RC conversions, so one looked for a NVA to use. OS is somewhat expensive--at least compared to the cost ($9)  I paid for ST assemblies from Tower. I think the OS's go for ~$15.

When you are learning, and flying profiles where the needle is pointing straight up, it is amazing how many $9  ::) inverted landings you make!

Title: Re: Super Tigre NVA
Post by: Bill Little on July 25, 2006, 08:15:29 AM

I only get PA needle valve assemblies from Randy at Aero Products now.  He has them made for all size engines.

They have all the features of the ST, but like Steve pointed out, they have a nylon cone in the needle locking nut.  That allows the nut to only be finger tight (my fingers) and the needle will not turn unless you turn it.  The nylon cone also insures there are no air leaks there.

The needle locking nut on the ST NVA can get loose after a while and tightening it enough to keep the needle from turning while the engine is running gets to be a pain.

Bill <><

Title: Re: Super Tigre NVA
Post by: Dick Fowler on July 27, 2006, 11:54:48 AM

What is the spraybar O.D. of the PA needle valve assy.?

Title: Re: Super Tigre NVA
Post by: RandySmith on July 27, 2006, 12:50:47 PM

Quote from: Dick Fowler on July 27, 2006, 11:54:48 AM

What is the spraybar O.D. of the PA needle valve assy.?

.157  same  as  a  ST   or  the   OS  FSR  NVA , the only  exception is  the   SS  FOX  PA  style  it  tapers  down to  127   same  as  a  FOX

Regards
Randy