109jb

OK did some digging on the internet and it seems it would be somewhere about 30 lbs weight gain, plus the cost of a new prop or at least new blades.

So bringing this one back up because I'm getting ready to do something on my 582.  I want to make sure my thinking is correct before proceeding. In this and the other associated thread there are basically 2 systems presented and I would like to discuss the merits of both. So the 2 systems I'm talking about are Chris Bolkan DIY Hacman type system and the vacuum pump system by Cowlove. Here are the links to the posts with the descriptions/plans

DIY Hacman - http://www.avidfoxflyers.com/index.php?/topic/5717-leaning-the-carbs-for-altitude-on-the-cheap/&do=findComment&comment=53166

Vacuum pump - http://www.avidfoxflyers.com/index.php?/topic/5717-leaning-the-carbs-for-altitude-on-the-cheap/&do=findComment&comment=53084

Both systems work by applying a small amount of vacuum to the carb bowl vents with the difference being the source of the vacuum. I am interested in putting something on my airplane not for high altitude operation but primarily for ambient temperature changes. I don't mind changing needles or jets a couple times a year but around my area, and I'm sure others, the temp can vary wildly from one day to the next. I plan to fly year round and in bitter cold to hot temps. Changing jetting a coulpe times a year is fine but in the winter months it could be every other week.

With the DIY Hacman system, or for that matter the "real" Hacman system, the vacuum source is the carburetor venturi, so the amount of vacuum you get varies depending on throttle position. This means that changes of throttle require adjusting the valve to again achieve the proper mixture. The instructions for the "real" system state that the valve should be closed any time a throttle adjustment is made. 

With the vacuum pump setup the pump supplies the vacuum. With a well regulated electrical supply the vacuum should be constant. So with a constant vacuum source the float bowl pressure should be constant just like it is with no leaning system. As far as I can tell, with this sytem, even with the pump on, the mixture should behave normally with throttle changes.

Getting a little more into it, the Hacman system uses manifold vacuum which is inversely proportional to throttle position. IE: low throttle - high vacuum, high throttle - low vacuum. So lets say you have the Hacman adjusted to provide good EGT at a cruise power setting. If you open the throttle the vacuum drops and the mixture gets richer. Conversely if you retard the throttle the vacuum increases and the mixture leans. The system works, but seems like it would be a pain to use for something like touch and go landing practice.

Now the vacuum pump system has constant vacuum which would not change for any throttle position. It seems that if you were doing that T&G landing practice that you could set it and pretty much forget it for that flight. Then it could also be used for leaning at altitude.

It seems to me that the vacuum pump system  would be less cumbersome to use, simpler to install, and not require any potential carb drilling. I'm wondering why this isn't the more chosen route compared to the Hacman type system.  

Am I thinking about this right? Is there something I'm missing?

I have a Kitfox IV with a 582 and warp drive prop and am thinking about what I want to do when it comes time for the 582 to be overhauled. It is actually past the 5 year limit already. I'm thinking about keeping my eyes open for a 912 nearby and doing an engine swap. So that brings up a couple questions:

1. roughly what should I expect as far as the airplane weight difference goes between the 582 and the 912 installations. 

2. Would the Warp Drive prop I have be suitable for use on the 912 or am I looking at needing a different prop. I'm not sure on diameter but it has HPL hub, 3 blades, and reduction ratio in the 582 is 3:1

Yeah if the stud doesn't protrude into the ID of the main horizontal tube, then the internal sleeve is still the way to go. Do the same to both sides as the other side is obviously bent too.

Its a homebuilt so it doesn't have to be welded by any certified weld repair station.  Their quote is just a way of saying we aren't interested in this piddly job.

Ask around and find out who in your area is a job-shop welder with good TIG welding skills and they should have no problem and it should be cheap. Ask guys who do car stuff. they will know someone. Also, do you belong to an EAA chapter? EAA chapters are a good source for people that can do a variety of things. The repair that part needs is simple for someone who knows how to weld. I know that is the problem many times but finding someone who can weld should not be that hard.

The way I would normally fix a tube would be an internal sleeve repair with rosette welds along with the weld around the break. For that geometry though, the stud will prevent an internal sleeve, so I would first get it back in shape, weld the fracture completely, dress that weld, and then make an external sleeve/reinforcement to weld on the outside. Because of the way it is bent, check the other side for cracks too. 

If you were near me I'd repair it for some chit chat and a beer.

All of the Kitfox Service Bulletins and Service Letters are at this link:

http://www.kitfoxaircraft.com/index.php/ct-menu-item-1/technical-f-a-q

Experimental Amateur-built Airplanes do not have airworthiness directives

Even without a Repairman certificate, anybody can do maintenance, repairs, modifications, etc. The ONLY thing a Repairman certificate or a A&P is needed for is the Annual Condition Inspection. That can be done by an A&P and it doesn't have to be a mechanic with an Inspection Authorization (IA). That said, I just had my Kitfox IV  Annual Condition Inspection done by an IA (owner assisted), and it cost me all of $200.

So you are either going to have to lie to the feds to get a Repairman Cert, or just suck it up and pay a little for the freedom that we have wrt homebuilding.

BTW, how do you know that there aren't feds that read this forum?? 

Been doing some flying and put a couple videos on YouTube.

Well I went out flying yesterday and flew over to a friends strip. He has a Kitfox IV 1200 whereas mine is a Kitfox IV 1050. Here is where you can't believe the internet. Everything I read online said that the KF IV 1200 tail is 10" taller than the KF IV 1050. IT ISN'T!!! I checked the two airplanes and it is 53" - 47" = 6" taller. The rudder is 2" wider as well.

So I've decided that I will make a new rudder for my airplane to try out. So that I don't have to modify the vertical stabilizer or fuselage, I will make all of the changes to only the rudder with the new rudder having an aerodynamic counterbalance to achieve the taller height. I'm thinking I will make it about 8" taller and 3" wider that the stock 1050. This will be very much like @Av8r3400 did on his "Mangy Fox" and will be a bit larger than the 1200 rudder as well.

I've seen your airplane and I'm thinking of doing similar, by just making a new rudder with a counterbalance and squaring off the top front of the vertical. Doing it this way I wouldn't have to  mess with the fabric on the fuselage as long as the post for the vertical stabilizer is strong enough to handle the taller rudder. 

No. What I mean is the airplane has what I would describe as neutral to slightly negative yaw stability.  Keeping the ball centered requires constant pilot input, especially when there is any turbulence. Flying a cross country of any distance with this type of stability would be tiring and in my view unnecessary if it can be corrected. That is my goal.

So I have a Kitfox IV 1050 powered by a Rotax 582. It flies very well except for yaw which I'd describe as manageable but tiring. It would certainly be a drag on any trip of significant time.  

I've read that the Kitfox IV 1200 had the height of the vertical tail and the rudder increased by 10 inches to help with the yaw stability. I am contemplating making changes to my vertical stabilizer and rudder this winter. This brings up a few questions.

1. Does this mod "solve" the yaw stability issues?

2. With the increased height was there an increase in wall thickness of the tail post or rudder post?

3. Is there a "better" mod to help with the yaw stability?

Thanks in advance,

John Brannen

I finally was able to get checked out in my Kitfox today. It was a bit reminiscent of my first solo 37 years ago with the instructor telling me to pull off to the side and let him out. Felt really really good especially since I have basically been out of flying for about 10 years.

I have used the Harbor Freight 20 oz gravity fed HVLP spray gun for tons of things. It is a good gun and a great value. I've sprayed primers, color coats, clear coats, latex, solvent based, 2-part urethane, epoxy, primers, high build primers, and more. It has done a great job on anything I've put through it. I used it 2 winters ago to paint the replaced rockers and hood on my truck. Used it for all primer, base and clear coats and it came out fantastic. A buddy of mine that restores classic cars still can't believe that the finish I got was done with a gun that cost me $10. 

Flanders cables

I like the horizontal shock cord idea.  I just got a Kitfox IV with the stock gear and the shock cords are good, but there is no safety cable or anything.  Can I ask the size of the cord you used and if you tested to see if it will hold a tip off of the ground?

Hello all,

I'm a relatively new member here and earlier this year bought a Kitfox IV 1050.  I had some fixing up to do on it because the fuselage bent during trailering it home.  That is all fixed now though and the airplane is flying, well it has flown twice for about 2 hours total.  I've been dormant wrt fling for several years so am working with an experienced kitfox instructor to get back in the saddle. I figure I have at least a few more hours before I'm comfortable.  I actually bought the airplane beginning of August, but had to fix the trailering damage, add brakes to the right side, fix a bunch of little things...  Anyway, here are a few pictures. One is a picture o

Hi there. I'm new to the forum having just bought a Kitfox IV. I also have a Sonerai IIL that I built and here is how I look at it.

I am listed as the manufacturer of my Sonerai. Contrary to what the pdf liability statement Allen sent out, that NEVER changes. It is in the permanent FAA records of the airplane. That alone makes this particular liability waiver suspect enough that I would not use it.

The liability statement covers (maybe) the person who signs it but probably nobody else. In reality it probably doesn't even cover that. See the EAA article linked later.

I also don't buy the whole "In most states (California excluded) the parents can sign away the rights of their children, adult or not."  I'm 54 year old and I really doubt that any court would think my 79 year old father can sign away my rights. 

Certainly if Bob buys my airplane I can have Bob sign the waiver, But being a 2 place airplane, if Bob gives Sam a ride and crashes, The liability won't help one bit against Sam. Or if Bob crashes into a schoolyard full of children it won't help there either.

The EAA may have put out that one posted earlier but it isn't the one I am familiar with. I am familiar with the one I am attaching and will say even this one is only at best a deterrent.  Iron clad is absolutely not the case here and here is EAA's position on it which is also mine.

https://www.eaa.org/eaa/aircraft-building/building-your-aircraft/next-steps-after-your-airplane-is-built/selling-and-buying-articles/part-3-waiver-and-releases-buying-and-selling-a-homebuilt

As far as "The EAA says that nobody ever won a suit against anybody else when flying an experimental aircraft.", look up the John Denver case.  Everyone and his brother was sued on that one. Although I have never seen anything saying the builder of John Denver's airplane had to pay out, Aircraft Spruce and others did, and I'm sure the builder at least had legal defense fees.

For my Sonerai which I am listed as the manufacturer will be mine until I die. You would think that my liability ends there, but my estate could then be liable. For my Sonerai, that is worth maybe $10k if that, it isn't worth it. I would cut it up and sell it for scrap or part it out before accepting the liability of selling it regardless of what the chances of being sued are.

Bottom line is if you are going to sell your homebuilt airplane it doesn't hurt to have the buyer sign a waiver, butit is at best only a deterent.

Experimental Amateur-Built Aircraft Purchase and Sale Agreement.pdf