I recently acquired a .46VF and would like some info on setting this up for stunt. Any info would be helpful as to venturi size, fuel, starting pipe lengths etc..

Thanks in advance!!

Thanks Randy!!

Hi Brett or Randy or others,

Do you know what year and issue David's set-up article was? Yesterday was my first day running the VF in the garage, all mounted and ready to go. I used a 5% Power master with extra castor to bring it up to 22%. Pipe length is about 18.5 inches, but I'll double check. Plug has an idle bar but can't recall the make of it. I had a little trouble going rich and lean.


Prop was an APC 12.25x3.75.

This is Jimby's old VF and I have a CF prop from him, but wanted a cheap alternative for the first few flights.

David

I'm gonna talk to myself for a minute, but I'd still like to see where to find that 46vf set up article. But I discovered some bubbles where the head screws on to the motor. I tightened it down and what would you know, it holds a needle setting now. I may be ready to maiden this bird this week.

   I will have to check tonight, I gave him some information and was the proofreader for that one, so I should be able to find it. I am sure David would be happy to tell you, but he might end up talking you in to helping him hang drywall in his garage.

    Brett

   I will have to check tonight, I gave him some information and was the proofreader for that one, so I should be able to find it. I am sure David would be happy to tell you, but he might end up talking you in to helping him hang drywall in his garage.

    Brett

Do you know which month/year of Stunt News contains that 46VF setup article?

........, so presumably, Nov/Dec 2009, or early in 2010........
      Brett

Yes, the copy of SN where the article appears is called "Special Edition 2009", it is the same number on which "The Stiletto Chronicles Part III" appears (Part II is in Nov-Dec 2009)
So between Nov-Dec 2009 and Jan-Feb 2010.

Massimo

Here is a PDF the 2009 Stunt News article:  Tuned Pipes for CL Aerobatics, by David Fitzgerald and Brett Buck.

Well, I made what I could out of that article. I've had about 5 flights or so, frequently ending with the engine going lean from the header coming unscrewed. I suppose I need split washers to help hold it. Today however the engine held the same speed the entire flight, but that was, I believe...too lean. It just sounded a bit lean. Additionally, I was getting about 4.5 laps. So, my question is, am I too lean, (I was also much louder than usual), or do I need a flatter prop.

I used power master 10/22, APC 12.25/3.75, 65' lines. I heard you are supposed to control speed with prop pitch, but it still seemed a bit too lean. Any pointers. Oh, and weather permitting, Nov 21 I think should be tuned pipe day at Napa...weather permitting.

     If it is both too fast, and too lean, the obvious solution is to richen it up. Unlike the 40VF, the 46VF was often run into a 4-stroke, and both the 40 and 46 have a *butter-smooth* break from 4 to 2.

     Certainly use lockwashers, but as long as you use the sealant properly and have *perfectly flat* mating surfaces, you shouldn't have much problem with the header coming loose. The 40 and 46 have ZERO TOLERANCE for leaks at the header, if they leak, they tend to run with way too much boost and break (because the pipe is no longer constraining it) and also sometimes act like they are running on suction, speeding up/going leaner throughout the flight.

    As always,

    *face off both mating surfaces with 240 grit wet/dry sandpaper and oil, taped to a perfectly flat hard surface or lapping plate* Don't let it "rock" as you push it back and forth, you much have a perfectly flat surface on both sides from edge to edge

     Clean both surfaces with lacquer thinner or acetone until it is perfectly, operating-room clean.

    Clean the screws and clean the threaded holes to the extent possible, remove all oil it is possible to remove.

    Apply silicone sealant in a thin film all over the mating surface of on the engine side (which is smaller than the header flange, no point on covering that), all around edge-to-edge. DO NOT USE A GASKET OF ANY TYPE.  I use Permetex Ultra Copper car exhaust header sealant, but just about any silicone sealant will work.

     Put the screws (with split or star lockwashers on them) through the holes, and allow just a touch of sealant to get in the screw threads.

    Without allowing the flange and exhaust to touch, start both screws a few turns.

    Push the two surfaces together then run the screws down tight. Torque them down until they are tight and read-to-go. Ignore any advice on the tube of sealant about just snugging them, waiting overnight, then hard-tightening them later to form a "cushion" of sealant. You don't want that, it might blow out, you want to squeeze it out as much as possible, leaving sealant only in the scratches made by the sandpaper.

   We have *never* had a leak doing it this way, I have them that have been mated for 25 years with no leaks. I have also seen one or both screws back off, but the header stayed on just from the adhesive with no leaks. You *can* get it off later, but it's glued on pretty good.

   And I cannot emphasize this enough, *do not, under any circumstances, use any gaskets (paper, aluminum, brass, anything)*. All that does is give something to blow out, and is definitely unnecessary to seal the joint.
     Brett

Thank you Brett, that is GOLD! I will set to work on that next chance I get.

Also, are you saying a bit of a 4-2 is okay on a 46vf? I thought I heard somewhere to just go straight 2 cycle, but perhaps I'm mixing up my LA 25 advice, which I finally bought for my black tiger, but that's a different story, and one that may be turning out with a happy ending once I replumb my tank again.

I setup  many  o f these   engines  and most everyone  ran a  fast  4 stroke with beeps  of 2 at the  top, You can even  run  a  typical 4/2  break  with the  46 VF  on pipes

Randy

   The aluminum screws are probably the problem in this case. They can expand with engine heat, especially right there at the exhaust. The silicone for loctite seemed to have worked for a while. Use steel bolts, as long as possible to grab as many threads as possible but with out bottoming out in the hole, and try the silicone for loctite again. If it comes loose again after several flights, look for the red permanent loctite and try that. If the word permanent bothers you, don't let it. You will be able to get it apart when necessary with some careful heating.
    Good luck with it,
     Dan McEntee

Hi Again,
So, I've done about five flights and everything was fine until yesterday. On my second flight the engine started going very lean again and sure enough, the header has come loose again. I'm not sure why, but I have two theories? I used soft aluminum screws to hold the header on. Perhaps a little too soft and didn't squeeze hard enough to stay locked in position? So, I'll go again with steel screws. Also, is there a super threadlock I could try on my screws. I just let a tiny bit of the copper silicone on the threads. It was the best so far, but six, actually, I think it was four flights until coming loose.

On a positive note, this is my Junar with oversized stab and I really am liking the way it flies.

Hi David
Never  us e aluminum  bolts to hold a header in an aluminum  case, Where did you get  3.5 mm  aluminum bolts  from?  Are you using  the correct bolts  for the  46VF, they are 3.5 mm  x  12 to 13mm  deep,  using  anything else  will  not work with the threads on th e case.
The 12.2 x 4.2  2 blade  works  perfectly fine on that engine, as  so many people have used that in the past, it is a close  to a bolt on and fly  as you can get.
The small Aeropipe  made  for the VF 46  VF 40 is  also perfect for that engine, and can be  made in either a  9  or  10mm  exhaust outlet, That is a standard  pipe  that has been used on 100s of VF engines, Do not believe  anyone that tells you different
You can also use a  12 inch narrow 3 blade  or  a  3 blade  standard width prop from 11.25  to 12 inch diameter  that would  just be a personal choice

Randy

Hi Randy, this is an engine that belonged to Ed Southwick. Either he, or someone else modified the case (possibly out of necessity) and it takes 8/32 bolts. For the plane it was in (an impact) it worked for years and years, but when I got it I lost the bolts (like an idiot) and substituted the aluminum ones.

Well David  if the  8/32 threads  are  still  good in the  case, you can find  steel bolts  to use, I would do that,  I think it maybe a problem with 8-32  heads  clearing  the header  so watch  for that very carefully,  Use  blue locktight  AFTER   you have  cleaned  everything
I use  duct tape  as a gasket, this is the very best thing you can use, and by duct tape, I mean  the  tape that A/C people use to seal the  supply vents,it is  a  shiny metal looking tape  with  paper on one side, You peel the paper  off, stick  the header  to the tape, cut out the  screw  and  center  holes, then  you are ready to bolt it on.
The tape  is very thin like aluminum foil so it will not  crush and let the bolts  get loose
Use  the lock tight and tighten it all up, I never  have things come  loose  using this technique

If it was Ed's  It maybe  one of the ones  I did for him

Regards
Randy

  David,
  I don't use locktite on header bolts I do however use a split washer or a star washer if it all fits I prefer external star washers for a header also check the bolt tightness after the first flight then recheck every 3 or so flights for the next 15 or so flights then every once in  a while.
  Good luck ,  John L.

Hi everyone, good news is I got to go fly today.  Good news, the header stayed attached, the engine ran even on the insides and outsides. But, it kind of chugged a bit, like it was too rich, but I'm not sure. It was more like someone was flipping a fuel switch very quickly at certain times in the flight. There was practically zero acceleration on the stunts, which was something new to me.  So, it was about 52 degrees, 76% humidity. I think Brett or someone mentioned using 5% in the winter. I was still using my 10/22. I also made 4:20 or less with 5 oz of fuel. Maybe I'm still too rich, but I thought I'd ask about the nitro.

   If you have problems, recall that it is not intended to run rich, so increasing the RPM and reducing the pitch to match will generally make it run better. What prop at what pitch, and what was the ground RPM?

   An alternative is to reduce the venturi, so you can run it leaner with the same prop. It's actually very critical, one time we were out with Scott Urabe and his 40VF. .270 venturi, and he had to launch rich enough that it would 4-stroke in level flight sometimes. .265  shifted it a bit leaner, and he picked up, and I do not exaggerate, 40-50 points in 3 flights.

   If it is too "flat" in the maneuvers and everything else is OK, push the pipe in 1/4" and try again. But the effect of a proper piped engine run will feel like that if you are used to 4-2 break engines. First time I did it, I was almost afraid to do a wingover, because if had been an ST46 (like the previous week) it would have been far too slow to make it. Point the nose up, and it slowly grinds to the top of the circle, coming down, it was like someone was riding the brakes, absolutely amazing. Welcome to a new world.

    Brett

David, if you want to try the aluminum tape that Randy mentioned, just send me your address. I'll send you a chunk. Uline sells the good stuff for about $74 a roll. Like he said, it's for sealing, so it can be pricey. We use it to seal hydraulic ports that are too large for plugs.

https://www.uline.com/Product/Detail/S-10311/3M-Single-Coated-Tape/3M-425-Aluminum-Foil-Tape-2-x-60-yds?pricode=WB0161&gadtype=pla&id=S-10311&gclid=EAIaIQobChMI2ty2peLb7QIVnx-tBh2RQAAoEAQYBCABEgIRDfD_BwE&gclsrc=aw.ds

   Never use a gasket of any kind, use the Ultra Copper silicone sealant, properly applied it will last until you intentionally break it.

     Brett

   Never use a gasket of any kind, use the Ultra Copper silicone sealant, properly applied it will last until you intentionally break it.

     Brett

Properly  applied as  I described  the  Tape  will  NEVER  leak and will stay there  until you remove it.
The reason  people get into trouble  using gaskets and the reason Brett thinks it is bad, is because  they are  thick and  crush, then the bolts get loose from the  crush, then after they crush, they leak, The  THIN metal tape  I use, and  many many other  hundreds of people  use, at my suggestion, does  NOT  crush and  , thus it does not promote leaking,
I have used this  for 3 decades  and  have  never  had  1 problem, Many others have too.
So  do not let  anyone  tell you this  does not  work great.  It does, and in my opinion  it worked  BETTER than anything  I have  seen or  heard about,  Including  any silicone or  copper  sealant


Randy

The engine is running nice and smooth. No more problems with loose headers. I leaned it out a bit and went to 5%. Still using an APC 12.25x3.75 I think.

On 5 oz I'm running out of fuel at about 3 minutes each time. Laps are 5.25-5.4, which I don't mind too much. I think I'll measure the venturi as best as I can and consider going with a smaller venturi. I also have a CF 3 blade that was given to me with the engine. PRobably the same prop Ed Southwick used on the engine. I'm just not sure why I'm running dry so quickly. Also, plane doesn't turn inside and outside equally, which is a different thread, so don't worry about that one yet.

The engine is running nice and smooth. No more problems with loose headers. I leaned it out a bit and went to 5%. Still using an APC 12.25x3.75 I think.

On 5 oz I'm running out of fuel at about 3 minutes each time. Laps are 5.25-5.4, which I don't mind too much. I think I'll measure the venturi as best as I can and consider going with a smaller venturi. I also have a CF 3 blade that was given to me with the engine. PRobably the same prop Ed Southwick used on the engine. I'm just not sure why I'm running dry so quickly. Also, plane doesn't turn inside and outside equally, which is a different thread, so don't worry about that one yet.

   What venturi and spraybar are you using?  I would have started with a .265 and a ST spraybar, but if you have a smaller OS spraybar that will be way too much. 

    Brett

So, unfortunately I built it with a 5oz tin tank. The tank runs very dry each flight.  Sorry to be old school here, but I still don't have an accurate micrometer or measuring tool. So, I'm using drill bits here. 11/64 fits, 9/32 doesn't. It has an ST spray bar. Perhaps the CF prop will help, but it needs a lot better fuel consumption. But, if 5 ounces is too small, then I already know what I need to do.

Do you mean 17/64 fits and 9/32 doesn't?  9/32 is 18/64, so that's quite a jump.

Dunno what you mean by "runs very dry each flight" -- since that's kinda the point, I'm wondering how long your flights last?

As a last resort, if you doctor up your fuel with no more than 2oz of Coleman lantern fuel (AKA white gas) per gallon, you'll get about 10% more run time -- and slightly easier starting.

So, unfortunately I built it with a 5oz tin tank. The tank runs very dry each flight.  Sorry to be old school here, but I still don't have an accurate micrometer or measuring tool. So, I'm using drill bits here. 11/64 fits, 9/32 doesn't. It has an ST spray bar. Perhaps the CF prop will help, but it needs a lot better fuel consumption. But, if 5 ounces is too small, then I already know what I need to do.

     5 ounces is too small. 9/32 is .2812, which is bigger than I would start with, particularly with such a light prop. 11/64 is only .1718, so I presume that you mean 17/64, which is .2656. So, maybe .275, which is A LOT of power on a 46VF.

    If it runs and performs OK otherwise, I would just stick enough fuel in to make it on 10%, and move on with life. But, I think you will want to at least look at getting a set. I got mine from Leonard Neumann, but I am sure Randy and Jim Lee have them or can make them.

     My choices would be .260. .265. and .270, for a starter.

     Brett

p.s. How is it running in level flight at normal speeds? I would expect it to be 4-stroking most/all of the time with that prop, OR, two-stroking but very "flat" in the maneuvers because the pipe is too long.

    Don't do anything different until you can get complete flights in, but you can play off the pipe length against the venturi over small ranges to adjust how much boost/brake you get. You can set it up to 2-stroke with a .300 venturi if you run the pipe long enough, problem is that it will be dead as a doornail in the maneuvers. Pushing the pipe in would make it run richer at the same RPM, or, allow you to run a smaller venturi at the same mixture at the same RPM.

Okay, thanks everyone. My next step is figure out how to get a bigger tank in there and order some smaller venturis.
Brett, I'm not sure I have the vocabulary for piped engines yet, running flat?

I did put it in a rich 2 cycle last time out. There wasn't a ton of authority, and seemed like almost zero surge in power. Although that was okay, it still pulled enough to do everything. But, I'll figure out the tank first. I have the pipe as long as I can get it, so hopefully I don't need to go longer. Glow plug to pipe end is about 20.25 (I think that's a tad too long.) Then I have an exhaust deflector, so 21.5.
I can't tell you what kind of pipe it is except it's CF. First one I've ever had, may or may not be the one that Ed used on the engine. My dad had about three and I just took whatever.

  "Flat" means that is has very little boost or braking action in the maneuvers. If it is running that way with an oversize venturi, that strongly suggests that you have the pipe too long. It is regulating the RPM too well. A little longer, and you will go over the top, and you will hear it slow down in the maneuvers when it is supposed to speed up. It is very surprising to me that you can run it in a 2 stroke in level flight at a reasonable speed with that prop, that also suggests the pipe is too long.

   Normally you measure the pipe length by sticking something into the front to measure where the first baffle is, that is, the one closest to the engine. That is just a reference mark, it means different things with different pipes. With a Randy pipe and an 46VF I would start at 17.5" to the first baffle and then adjust.

   What I expect to happen with an oversize venturi is that it will be too rich in level flight and also vary too much during the maneuvers, when you have the pipe length otherwise right. Since it is 2-stroking in level flight and also too flat, apparently, it acts like the pipe is too long.

   But, first things first, make a tank to get through the flight, then start messing around with adjustments. If you need to, make the tank thicker than 1" and just put the wedge, pickup and uniflow offset from the center so it lines up with the engine the same way

    Brett

So, for my last flight today I pulled out my Junar with the 46vf to see if the changes made a difference before tearing into the tank. Well, I put two ply silk over the venturi to simulate a smaller venturi. I also wondered what would happen if I turned my uniflow line around so it wasn't facing the wind. Brett, I got that idea from you when you mentioned making an air dam or something at Golden State. I still used the same APC. Oh, and I shortened the pipe, but only about 1/4 inch. Any further and I need to cut the header more. Well, it flew like magic. Okay, maybe not Harry Potter magic, more like Willow Offgood magic, but magic nonetheless. Those three little tweaks enabled me to get one lap past the clover before I went deadstick. Not only that, but I had more power than I've had before. Oh, and the tank holds more fuel if the plane is level while you fill it. I don't think I was getting the whole 5 oz into it previously. I'll be playing with it some more before I try swapping the tank (which will involve cutting out and relocating a bulkhead.

HI David
You have to know  where you are at with your setup, The pipe length is  measured from center of chamber in the engine, to the  first  reflective surface in the  pipe, or  a  baffler, In my pipes, if you have a  very  old  pipe, there should be a  white or  yellow marke near the back of the pipe, if  it is one from the past 10 years the  first baffle is  located a the  bump, near the middle part of the  largest part of the pipe at the rear,  If not  Brett told you how to find it.  Second  set it  at  17 3.4 inch  with that 2  blade, and if you run a  3 blade  it will  set at  18 to 18.5 inches.  Be very careful to NOT crush the front of the pipe, always  keep the  Zip Ties  on the metal insert and  never  on the  unsupported  part of the pipe, it will  crush and restrict the pipe.  IF you have the  system  apart,  Check to make sure  the  front of the  pipe, is  clear and  no obstructions  or  it is not  crushed down smaller
This time of  year  you should  get plenty of  power  from  5% nitro.  If you need  extra  run time, put 1 to no more than 2  ounces in a gallon of Acetone, or coleman fuel.
Let us know  what is going on

Randy

Okay, possibly my final update on this thread...(we'll see).
So, I only put in the 5 oz tank, so I was needing to replace it, but it was so close on run I decided to try the acetone in the fuel to see what happens. (Last week)  So, I searched and searched and found out I was out of acetone. Then I went to the hardware store and bought some more. I got to the field and decided to try flying off of the old abandoned road next to the soccer field I often fly on. I searched for a crack big enough to pound in my stooge stake. Finally I found an area that was pretty bad off. Next I tried to open the acetone and it was way beyond child proof. Try as I may, I didn't have the tools to open that cap. So I decided to practice with the fuel "as is." I ran out my lines, the stooge, and then I discovered I didn't have my fuel syringe. So I flew the electric and came home. (sorry to waste your time with that one.)

(Today) I mixed up the acetone at about 100:1. First flight it seemed rather anemic, barely getting through the square 8s and the clover, however I made it three laps past the clover for the first time!  Flight two: I leaned it out a bit more and it came on pretty good. Got the whole pattern in and I think 8 or 9 laps. So, no surgery to replace the tank at this time. Looks like 5 oz will do it. Oh, that includes me priming it from the syringe rather than from the tank.

With that said, thanks for all the tips, hopefully my next questions will not be related to the 46vf.