How to Slowing Down My Vector?

[Kafin Noe’man]

After more flights with my Vector powered by ENYA 35X with 10.5x4.5, I conclude this engine will run happy (steady and consistent) if I set the RPM above 11,000 with the needle position more or less on the ‘lean area’ — in my case less than 1 full turn from the full close.

If I try to go richer, the engine is running erratically and not good.

However, with the happy engine run setting above, the lap times is just too fast around 4.6 with 60 ft lines.

I was thinking of slowing the lap times with trying different line lengths, but the only available ready to use line here in Indonesia is 70ft lines. So without changing any engine setup, is it safe to try the 70ft lines coming from 60ft lines?
(Note: I’m not confident enough to make my own lines)

Based on math, the 70ft lines will put me in 5.3 sec/lap range which is supposed to be fine for flying stunt.

Any thoughts or ideas?

[Ken Culbertson]

No way should a Vector be flown on 70' lines.  You need to learn how to wrap lines.   It is really quite simple and after you have done it a couple of times you will ask yourself what you were afraid of.  It is the same as wrapping loadouts only easier.

Ken

[Kafin Noe’man]

No way should a Vector be flown on 70' lines.  You need to learn how to wrap lines.   It is really quite simple and after you have done it a couple of times you will ask yourself what you were afraid of.  It is the same as wrapping loadouts only easier.

Ken

I see, should I try another prop first?
11x3 perhaps? In theory, what will the 11x3 or 4 give coming from 10.5x4.5?

[Dick Pacini]

I would go the other way.  Try a 9X5 or a 9X6 prop. 

[C.T. Schaefer]

consider a smaller venturi and no longer than 60 ft.  Vector flys good at about 5.0.

[John Skukalek]

Seems like many of the experts say once you get the needle setting right to adjust speed with propeller pitch.

[Dennis Toth]

Kafin,
The simple answer is adjust the pitch. Based on your numbers drop the pitch to 4.25" should get you around the 5.0 lap time at 11K. If you don't have a pitch gauge to do the heat re-pitch try a stock 11x4" wide blade (like the old Top Flite or BY&O's) will need a bit more rpm (~12K). You didn't say what fuel N% or venturi but as CT said smaller venturi or add an inlet filter (could be just some old nylon stocking material a few layers will effectively change the venturi size smaller).

Best,   DennisT

[Peter in Fairfax, VA]

You should be able to wrap your own lines.  The technique shown in the video below is good, though I find the jig not needed.  I hold the thimble in my non-dominant hand, then wrap with the other.

[Ken Culbertson]

I see, should I try another prop first?
11x3 perhaps? In theory, what will the 11x3 or 4 give coming from 10.5x4.5?

Yes, I am not familiar with Enya's moods and cravings but if you have in running in it's comfort zone then the prop followed by the venturi.  The one I used for a season was electric so speed was a timer setting but the 5.0 lap time on 60' lines is perfect for a Vector.  I flew mine at 5.1 on 60' eye to eye lines.

Ken

[Dan Berry]

Cut 1/2" off the prop.
Put two layers of panty hose over the venturi.
Get the engine happy. Loose mounting makes the engine unhappy.
Once the engine is happy prepare to shorten the lines to 59 feet.

[Kafin Noe’man]

I would go the other way.  Try a 9X5 or a 9X6 prop.

Is it because with smaller diameter prop, we can get higher RPM without pushing the needle to the lean side?
There was a time when I accidentally ground or broke off the prop by 1” making it a 9.5x4.5. Somehow it mase the launch RPM to be around 11,200 and engine sounded happy, lap times was 5.15 sec/lap

[Kafin Noe’man]

Kafin,
The simple answer is adjust the pitch. Based on your numbers drop the pitch to 4.25" should get you around the 5.0 lap time at 11K. If you don't have a pitch gauge to do the heat re-pitch try a stock 11x4" wide blade (like the old Top Flite or BY&O's) will need a bit more rpm (~12K). You didn't say what fuel N% or venturi but as CT said smaller venturi or add an inlet filter (could be just some old nylon stocking material a few layers will effectively change the venturi size smaller).

Best,   DennisT

Hi Dennis, I can only find APC 11x4 here. Would that be working?

[Colin McRae]

Kafkin, I am curious what your Vector 40 weighs. My Vector is 'really heavy' at around 64 oz w/ a corresponding high wing load. (I did not build it so did not have control over the weight.) I am working away at how to trim and fly a heavy model. My Vector needs a low pitch prop spinning fast for power.

I am currently running a stock OS 40LA but have a 46LA in my back pocket if for more power is needed. I originally tried a 11-4 wood BY&O and am experimenting with APC 11-4, 11.5-4, 12-4 and 12.25-3.75.

I would keep the pitch at 4 and try different diameters and ground rpm to see how the model flies. And lap speed is one thing. How does your model do in the maneuvers and corners? If heavy like mine, you might need to fly it fast so it does not stall in maneuvers.

[Colin McRae]

Hi Dennis, I can only find APC 11x4 here. Would that be working?

I would surely try the APC 11-4.

[Kafin Noe’man]

Kafkin, I am curious what your Vector 40 weighs. My Vector is 'really heavy' at around 64 oz w/ a corresponding high wing load. (I did not build it so did not have control over the weight.) I am working away at how to trim and fly a heavy model. My Vector needs a low pitch prop spinning fast for power.

I am currently running a stock OS 40LA but have a 46LA in my back pocket if for more power is needed. I originally tried a 11-4 wood BY&O and am experimenting with APC 11-4, 11.5-4, 12-4 and 12.25-3.75.

I would keep the pitch at 4 and try different diameters and ground rpm to see how the model flies. And lap speed is one thing. How does your model do in the maneuvers and corners. If heavy like mine, you might need to fly it fast so it does not stall in maneuvers.

Hi Colin, my Vector weighs around 45 oz

[Colin McRae]

Hi Colin, my Vector weighs around 45 oz

WOW! Is it a Brodak Vector 40 w/ a 50.5" design wingspan, or some other version? Does that weight include 'everything'? I have never heard of a Brodak Vector 40 being that light. Is it an ARF?

Mine was not an ARF and professionally painted. Just goes to show you how much paint can weigh!!

[Ken Culbertson]

This is starting to remind me of an experience I had with an OS46FX.  I built a profile around it after just returning to the sport after a long pause to raise 2 girls. It was moderately large about 650 sq and light for it's size 54oz.  The FX ran beautifully in it's proper envelope which was a wet 2 stroke.  The problem was a 4.2 lap time on 63' lines on an 11 x 4 prop.  Nothing I could do made the motor want to perform slow enough to be usable without a pipe.  I ordered a header and a pipe in 2018.  Still waiting for it.  In the meantime, I pulled the FX and replaced it with an LA and had a plane that performed well even against full fuselage PA planes.  The ball bearing "X" motors are mostly high-performance RC motors designed for 3D or helicopters.  I checked the RC sites and the ENYA 35x is just that.  If an 11 x 3 or 10 x 3 (which are extreme compromises) doesn't work, you may need to consider a less aggressive engine.  I will leave which one to the engine experts among us, which, I am not!

Ken

[Brett Buck]

Hi Dennis, I can only find APC 11x4 here. Would that be working?

   That would be an excellent choice. Your current problem is *too much pitch* but more-or-less illustrates how I recommend these engines be run stock.

    Brett

[Doug Moisuk]

You should be able to wrap your own lines.  The technique shown in the video below is good, though I find the jig not needed.  I hold the thimble in my non-dominant hand, then wrap with the other.

I was told never to epoxy or solder the ends  I also put a piece of heat shrink tubing on the line before I start rapping. I make one red and one black to make hooking up to the plane easier to get it right. Of course I put the heat shrink on the braided lead outs coming out the wing as well.

[John Carrodus]

If all else fails Kafin, tow a combat streamer from it or an RC glider

[Kafin Noe’man]

Smaller venturi or add an inlet filter (could be just some old nylon stocking material a few layers will effectively change the venturi size smaller).

With the pantyhose, it will drop the RPM at my current setting, right?

So if my best needle position now is around 1 full turn and it gives me 11,000 RPM, when the pantyhose is installed, the RPM should drop to around 10,000 RPM, right? It’s like dropping RPM without having to set the mixture richer, isn’t it?


Best,
Kafin

[Peter in Fairfax, VA]

Doug,

Yes, no solder or epoxy, as it creates inflexible stress points.  Just the line, the thimble and the brass or copper serving wire.

thanks,

Peter

[Kafin Noe’man]

Or should I switch back the tongue muffler into the stock (tube) muffler?

[Brett Buck]

Or should I switch back the tongue muffler into the stock (tube) muffler?

  I don't have any specific information on this particular engine, but running the *stock* muffler (and everything else) is an important key to all the similar engines I have tried. That is probably why it is unstable, the same thing happens on the 20FP, 25FP, 25LA, and to a lesser extent, the 46LA.

    Brett

[Steve Helmick]

Experimentation is in order. Try the same prop with one, two, or three layers of panty hose material over the venturi. This will effectively reduce the venturi size, so the same NV setting will likely be richer.

I'm a big fan of APC propellers, but think it's a shame that folks don't more often work on these to adjust diameter and blade shape. For my OS .46VF/pipe model, at one point I was recarving a 12.25 x 3.75 APC to 11.5" diameter. Blade shape is much like an APC 11-4. I subsequently changed to a 3 blade Brian Eather CF 12-4UC trimmed to 11.5" and pitched at about 4" with more pitch toward the tips. Probably not optimal, but better than previous props.

You might get lines of 64' eye to eye to work, but not likely for a .35, and certainly NOT longer. I found that a foot longer or shorter makes a big difference in getting steady line tension, and STEADY line tension give a better result than slower lap time. I flew my 50 oz. Twister on a Magnum XLS .36 and had better results changing from 60' to 59', for example. Line length is pretty much dependent on engine size and propeller diameter. Speed and weight increases line tension.

Assuming you are flying CCW, do you have some right thrust in it? Paul says 1.5 degrees. Remember that prop and line size and length are all part of TRIM. I suspect you will have other trimming adjustments to make. Trimming is NEVER done, but always be able to put it back the way it was if the new adjustment doesn't help.  Steve   

[Kafin Noe’man]

This will effectively reduce the venturi size, so the same NV setting will likely be richer.

So the pantyhose will drop RPM without me having to set the mixture richer at my current happy NV position/setting, isn’t it? And it somehow ‘widens’ the optimal stunt range NV position making it more ‘tolerant’ needle setting, right?

[Brett Buck]

So the pantyhose will drop RPM without me having to set the mixture richer at my current happy NV position/setting, isn’t it? And it somehow ‘widens’ the optimal stunt range NV position making it more ‘tolerant’ needle setting, right?

  Yes - to a very limited degree. Two layers of panty hose is not much of a change. I would much recommend returning to the stock muffler first, because assuming it runs like all the other FP/LA engines, it will be much more stable with the stock muffler with no other changes. This means you don't lose much power in the range you can use.

    Brett

[Kafin Noe’man]

  Yes - to a very limited degree. Two layers of panty hose is not much of a change. I would much recommend returning to the stock muffler first, because assuming it runs like all the other FP/LA engines, it will be much more stable with the stock muffler with no other changes. This means you don't lose much power in the range you can use.

    Brett

Hi Brett and all,

I have been busy with works lately, and I just got the chance to fly last Sunday. So, I just wanna give you some updates on my journey to trim my Vector.

My previous problem was dealing with the fast lap times, thus one of the possible solutions is to 'detune' the engine.
In order to do that, I decided to return to the stock tube muffler and adding some exhaust deflector. These two parts really did rob some power of my engine.

I did three flights in total,
the first and second flight:
- Stock Tube Muffler + Full Length Exhaust Deflector
- Launch RPM 10,150 -10,200ish
- Wet 2 cycling
- Lap Time 5.6 - 5.8 sec range (previously, I was always on the 4.7 - 4.8 sec range). However, with this 5.6 - 5.8 sec range, I was having some trouble to do the Wing Over, it felt like I didn't have enough power at the peak and I felt the line was losing its tension.

the third flight:
- Stock Tube Muffler + Shorten (by 1") Exhaust Deflector
- Launch RPM 10,280 -10,350ish
- Wet 2 cycling
- Lap Time 5.3 - 5.45 sec range. With this lap time, I felt like I was having better overall experience and I could do better Wing Over but I didn't think it gave the optimum output I was hoping for.

My next plan is to fly more with the latest (third flight) setup to see more and make the conclusion. If it still feels a bit lack of power, I'd start to shorten the deflector by half-inch and see the difference it'll make.

But in general, I'm quite happy that going back to stock tube muffler (whether with the additional exhaust deflector or not) turned out to be working good and put me in a good ballpark.

Thank you so much for your inputs and suggestions.


Best,
Kafin

[Dan McEntee]

Hi Brett and all,

I have been busy with works lately, and I just got the chance to fly last Sunday. So, I just wanna give you some updates on my journey to trim my Vector.

My previous problem was dealing with the fast lap times, thus one of the possible solutions is to 'detune' the engine.
In order to do that, I decided to return to the stock tube muffler and adding some exhaust deflector. These two parts really did rob some power of my engine.

I did three flights in total,
the first and second flight:
- Stock Tube Muffler + Full Length Exhaust Deflector
- Launch RPM 10,150 -10,200ish
- Wet 2 cycling
- Lap Time 5.6 - 5.8 sec range (previously, I was always on the 4.7 - 4.8 sec range). However, with this 5.6 - 5.8 sec range, I was having some trouble to do the Wing Over, it felt like I didn't have enough power at the peak and I felt the line was losing its tension.

the third flight:
- Stock Tube Muffler + Shorten (by 1") Exhaust Deflector
- Launch RPM 10,280 -10,350ish
- Wet 2 cycling
- Lap Time 5.3 - 5.45 sec range. With this lap time, I felt like I was having better overall experience and I could do better Wing Over but I didn't think it gave the optimum output I was hoping for.

My next plan is to fly more with the latest (third flight) setup to see more and make the conclusion. If it still feels a bit lack of power, I'd start to shorten the deflector by half-inch and see the difference it'll make.

But in general, I'm quite happy that going back to stock tube muffler (whether with the additional exhaust deflector or not) turned out to be working good and put me in a good ballpark.

Thank you so much for your inputs and suggestions.


Best,
Kafin

    I think you are starting to get the idea on how venturi sizes and exhaust can affect engine performance. keep doing what you are doing, and keep track of fuel usage also. If you restrict the exhaust too much, it will rob power and fuel used per flight will go down. The rubber exhaust deflectors are VERY restrictive and I always caution people to experiment with sizes and lengths just like you are doing. keep up posted on specifics of amount of fuel, and run times also if you can.

    Be advised that out National Championships are just starting here in Muncie, Indiana, and most of the guys that you are used to hearing from are there. I think everyone is there but me!! Again, keep doing what you are doing,  and let us know all the parameters of each flight, like amount of fuel, prop sizes, lap times, length of the run time, venturi size you are using, line length. It sounds like you are seeing some good results.
  Type at you later,
   Dan McEntee

[Steve Helmick]

What Dan said! But I'd also recommend going over to the Engine Tuning forum and read through Randy Smith's multiple articles that are pinned at the top of the forum. LOTS of good tips in there. Read them often! 

One of Randy's statements that I keep in mind is that changing the size of the muffler outlet gives much the same result as a similar change in venturi size. I like to always have at least a single layer of pantyhose mesh over the venturi just to help keep less dirt/sand from going through the engine, so that's where I start. If adding an exhaust deflector (aka Rubber Ducky) reduces power too much, then add Nitro or change to a bigger venturi.

I like to leave the 'rubber ducky' as long as I can stand, or for certain, long enough so it can be pinched closed. When you need to shut down the engine ASAP, pinching the rubber ducky closed does it faster than any other way. Putting your finger over the outlet also works, but then you'll have a burned finger...don't ask me how I know! Not that I regret getting burned in that incident, because it was really an urgent situation, but pinching the rubber ducky is not painful at all.  Steve