Kitfox IV Questions

[EDMO 1078]

It would sure be nice if you can record your speeds without the VGs, and then again after you put them on.

Did you read the post about putting VGs UNDER the wing for better cruise? It is way down below in "files", I think - Posted by Doug A+. This is supposed to add 10 mph cruise to undercambered airfoils.

ED in MO

I forgot that this is a 4 - don't know if the VGs under the wing will have any effect on the flat airfoil - I was thinking about the earlier Eppler airfoils.

Still, a report before and after would be interesting.

Ed in MO

[EDMO 1078]

What are the round objects above the IP, with a tube? running down each side?

Ed in MO

 

They are backup emergency panel lights, the are flexible and run on watch batteries.  They actually work quite well.

Interesting - had never heard of them before - LEDs, I guess?

Ed

[Mendlerr 4]

No they actually use a standard small bulb, like an automotive interior bulb so they arent the brightest but they do work. 

 

After searching I have found no clear articles on VG's and Kitfox's.  I think I may experiment some and use my Contour cameras to record the data.

 

So I'm holding off on installing the VG's and I'm going to do some testing on the upper and lower surface of the wing and flaperon. 

 

It will be a few months though, so don't hold your breath for too long

[EDMO 1078]

No they actually use a standard small bulb, like an automotive interior bulb so they arent the brightest but they do work. 

 

After searching I have found no clear articles on VG's and Kitfox's.  I think I may experiment some and use my Contour cameras to record the data.

 

So I'm holding off on installing the VG's and I'm going to do some testing on the upper and lower surface of the wing and flaperon. 

 

It will be a few months though, so don't hold your breath for too long

I don't plan on leaving the country soon - so will be waiting.

Thanks, ED

[Mendlerr 4]

Does anyone know of a good tailwheel CFI in the mountains of Western NC or Eastern TN?

 

My normal go to guy ole Johnny White is out of town for the rest of the month and no one else fly's tailwheels anymore.  It sucks.  I'm the only tailwheel aircraft on the airfield other then a Maule Orion.

[dholly 718]

Richard (right?) -

 

Couple thoughts...

 

If you haven't found it yet, the history of Service Bulletins and Letters is on the KitfoxAircraft.com website. ie. Service Letter #47

 

Also, look on YouTube for stall tuft tests w/ and w/o VGs. Can't recall if it was an Avid or Kitfox or what model, but it was an interesting video. Everything I've read suggest that VG's on the underside of a flat bottom KF4 or Avid Speedwing are ineffective. They do appear to provide some benefit under the early KF1-3 and Avid under cambered wing, but not so much on the flat bottom airfoils. I spent a great deal of time reading the various Kitfox forums and speaking directly to the owner of the manufacturer who supplies the VG kits sold by Kitfox Aircraft: Pacific Northwest Aero (I found an error in their install instructions!) before sticking them on my KF4. I put them on the upper surface of the wings and lower surface of the H.S. My chosen location was not per the manufacturer's instructions however, after multiple conversations with them, they agreed my placement might provide better results on the model 4 Riblett airfoil than their 'standard' application instructions. I put them on right when I got the plane so I did not get 'before' comparisons. I've pasted a testimonial below from another KF4-1200 owner w/ 912ul and Warp taper tip (same setup I have) that helped convince me to buy them. Might want to check this thread too if you haven't already >>> http://www.avidfoxflyers.com/index.php?/topic/1222-best-way-to-measure-for-vg-placement/

 

Hope that helps.

 

The vg's that come from Kitfox come with everything you need, right down to a little tape measure. They have vinyl decal material that is a template that you apply to the wing. It makes placement really easy. As far as placement, they're installed further apart near the wing root so that the inboard will stall first and the stall will progress outboard. I installed mine at 8% of cord after talking with the owner of Pacific Northwest Aero who is the owner of the company that the Mcbeans get them from.

Some people don't have much good to say about the vg's, but they made such a dramatic difference in slow flight. The plane is rock solid with very little mush. If you power off stall, with the stick all the way back, the airplane stalls then breaks, and instantly recovers without ever letting the stick forward. Power on the break is more abrupt with little warning. You used to be able to spin mine without much trouble, just stall it uncoordinated. With the vg's, it took three attempts before I could get it to spin. I would stall it uncoordinated and as the wing would drop a little bit it would recover. I've never flown something where you could stall it with the stick back and the ball off to the side and it wouldn't spin, or at least spiral. The plane just kinda slides off to the side, stalling and recovering. I was finally able to get it to spin by stalling it then kicking the rudder abruptly.

I like my vg's

Nick W.

 

[EDMO 1078]

No they actually use a standard small bulb, like an automotive interior bulb so they arent the brightest but they do work. 

 

After searching I have found no clear articles on VG's and Kitfox's.  I think I may experiment some and use my Contour cameras to record the data.

 

So I'm holding off on installing the VG's and I'm going to do some testing on the upper and lower surface of the wing and flaperon. 

 

It will be a few months though, so don't hold your breath for too long

Richard, Not sure what bulb you have, but have seen lots of LED replacement bulbs for auto bulbs, interior and ext - should make your batteries last longer if you ever need to replace a bulb.

ED in MO

[Mendlerr 4]

The dial is for the mikuni fuel pump. I'm not sure what it should be flowing, I've only used it to start the engine. I haven't needed to use it in flight

 

I found some issues when i pulled the carbs off a few hours ago.

 

For starters, the oil injection is setup wrong. At idle (3,000rpms) or with the throttle completely closed, the alignment marks are completely off.

 

The cable which actuates the lever is way too short and has no more adjustment to it. Hence the lever alignment marks not aligning properly.

 

The oil injection lever does not move smoothly and it will not return to the idle position on it's own, it requires manually nudging it with your finger to return it to the idle setting. The return spring has very little tension to it.

 

Pulled the plugs out, they arent horrible yet but they have around 3 hours on them and have some signs of fouling, probably because the engine is getting way too much oil.

 

This is the injection lever at full idle cutoff. The alignment marks are off. When the throttle is set to actual idle of 3,000RPMS this mark is way off.

 

Here is the linkage at full throttle, it hits the cable mount slightly, it will not return to idle completely when I pull the throttle back.

 

Here is a plug I pulled after idling, taxing and doing a runup to 6,200RPM's

 

Fuel pump adjustment, wish I had some more info on what the settings are.

 

This is the oil bath level after I leave the airplane alone overnight. I have to top it off before I start the engine each day. If I run the engine it doesn't affect the level, only when the engine is cold and has been sitting for a day or two.

[akflyer 1427]

You need a new cable for the oil injection pump.  If the cable is kinked, it will not return right on its own.  I have had to replace the cable on mine a couple times in the last 500+ hrs.  The oil from the RV tank can only leak into the crank case if the inner seals are gone.  This will give you a rich burn also and foul your plugs.  That oil has to go someplace and it will be right out the exhaust.  The dial on the fuel pump regulator is the rough PSI setting.  So you are putting about 3.5 PSI to your carbs.  This is about right.

 

The only way to do a good plug reading is to warm the engine up good with old plugs, pull the plugs out and install fresh plugs then fire it up and go WOT with it for 30 seconds or so, pull it to an idle and shut it down immediately.  Pull the plugs and see what they look like.  You will get plugs fouling a bit at idle and especially at a cold start up.  I don't see anything wrong with your plugs.  I like mine a tad on the fat side because I would rather change plugs every 25-30 hours versus leaning it out and trying to find a place to pull over cause I burned it down.  It sucks to find parking spots in a lot of the areas I fly so a little on the rich side is OK with me.

 

Second thought on the RV oil... is there any trace of oil in the coolant?  It could be leaking into the coolant when there is no pressure on it, or when the engine cools down and the coolant pulls a vacuum on the system.  When the engine is running, it could be creating enough pressure that the seal is being pushed in by the coolant and its not leaking coolant into the oil.  Normally when that seal on the RV shaft goes, you WILL be getting coolant into the RV bottle, or oil in the coolant system.

 

[Mendlerr 4]

there is no oil in the coolant or vice versa.  thank you for the very informative post as i am still a newb to 2-strokes.

 

I am getting a 50/50 reaction asking friends and airport bums that run 2-strokes and 4-strokes regarding premixing and injection.  I hear good and bad arguments for both.  in my mind premixing is the way to go.  but tell me what you guys think.

 

any good source for those cables? 

Edited 19 Apr 2013 by RMendler

[akflyerbob 41]

I can see possibly two problems. either

1. The crank case is leaking psi into the pump shaft chamber causing the shaft seal to leak

    oil into the rotary valve and the oil being sucked into the engine and burnt.

2. The seal itself is leaking oil under gravity into the rotary and also being burnt in the engine.

 

As for mixing thats not going to fix your leaking seal problem.

The seal is not going to "heal up" and guit leaking.

The oil inj system its self is not your problem, its the cable or the ajusting housing on top of the pump

where the cable housing fits. Should be seated and safetyed so it can't come out when slack.

As said before, the pump is designed to vary the oil to the engines RPM, throttle setting.

When Mixing, the engine always runs at 50-1. Harder on plugs, rougher idle, more vibration.

Rotax oil pumps have failed but I think it was the older ones driven from the recoil. Mostly not

the pump failed but the pump drive.

[EDMO 1078]

Richard / Doug,

After months of indecisions, I have finally decided to add the Ribblet mods to my undercambered ribs, after extending the leading edge 3 3/4 inches, and not ready to cover yet.

- Mine wont be exactly what he showed, because there would be an interference in the rear strut bolt attachment if I go by his drawings, so I modified the rear part, and ended the addition of the lower capstrip at the rear spar, and will just have to see how it acts in comparison with standard stol wings. This wont cost as much as adding the VGs under the leading edge, but I can also try that later on if I am not happy with cruise improvements. He says there will be little difference in lift, and I have long runways down here anyway. Hope to report someday.

Can post photos when done.

ED in MO

Edited 19 Apr 2013 by Ed In Missouri

[Mendlerr 4]

the oil bath seeping oil is due to a lower seal, I had it looked at and was told it would be no issue.  when the engine is under load and warmed up it seeps no oil, only once it cools down and sits on the tail for a few nights.  I was told as long as the level is checked before each flight I should have no issues.

[Mendlerr 4]

After speaking with a couple of rotax engine builders I was convinced to call Lockwood aero and get their oil injection delete kit(not on their website). It was $17 bucks and some shipping. I was also advised by them to use a 40:1 mixture instead of the factory listed 50:1. Apparently testing has showed that it help the lower bearings and low throttle setting lubrication.

[akflyer 1427]

at 40:1 keep a spare set of plugs in the plane.  When she starts popping and chugging and running rough when you pull the power back find a spot to land and change the plugs.

 

Joey has been running Amsoil 100:1 and has put alot of hours on his 2 engines so far on long CC trips and short local trips with no issues.

 

I am still a little old school and like to trust mine to quanitiy not chemistry

 

[Mendlerr 4]

opinions on how to run a 2-stroke varies so greatly.

 

I just met a few gents running twin engine air cams here.  They use 2 Rotax 582 pushers.  some of them had 1200+ hours on these engines.  They told me to use Phillips 66 2-Stroke oil at 50:1 and 1 ounch of Marvel Mystery Oil per 5 Gallons of fuel.  Apparently they have been very successful using this, the leader of the group, David, is a Rotax rebuilder and he also recommended this.

 

Talk to Rotax and they will tell you NO ADDITIVES!

 

Ask on the forums and they say 70-100:1 and you should be fine.

 

It's hilarious.  Idk what to believe, I'm not a 2-Stroke guys and I'm not sure what to do.  I did drain my wing and header tanks and remixed the fuel 50:1 with Penzoil AirCooled Oil.  I hope to burn this off in the next 2 days and put some fresh gas in it.  I hate to let it sit with fuel premixd in the tanks

[Mendlerr 4]

i have a corporate account with amsoil and I'm thinking of buying a 30 gallon keg or a 55 gallon drum but thats a big investment.

 

if i could really run the amsoil at 100:1 with no issues then this sounds like the way to go.  less ring sticking, fouling, carbon and consumption.  Sounds like a win, win, win to me.