Kit Aircraft Modifications

Hello Everyone,

News coming across the wire in the last couple of days is that David Carrigan from Prince Edward Island, Canada has flown the first RV-10 to be built north of the 49th parallel.

I had the opportunity to talk with Dave on the phone the other day as he had seen a post of mine and called to find out where I was in the construction of my ‘10. He hadn’t flown his yet when he called so I would like to publicly say congratulations to him for getting his new bird into the sky.

Dave has what I think is going to be a popular modification made to his airplane. He has swapped out the standard Van’s cowl for the new James Aircraft Holy Cowl. This is a cowl patterned after the successful designs of Ray LoPresti. It has the round inlets that have a significantly smaller inlet area. This along with the engine cooling plenum that they sell significantly reduce the drag on the airframe.

Here is a picture of Dave’s RV-10.

This cowl and plenum have just been made available for the RV-10 but they have been popular with the other models of RV. From the posts that I have observed on the Matronics RV-10 forum there has been some difficulties in getting the cowl installed and the majority of the issues revolved around the lower cowl exit louvers. There seemed to be trouble in integrating the Van’s produced louvers into the new bottom cowl. I have only got this second hand so I need to hear more information on this. I will post any comments I get to this page.

We are all hoping that the speed numbers will be better than the original and that the engine has good cooling. Dave has said that he will post some numbers as he gets more time on the aircraft.

I am working on a way to get you higher resolution photos to you. In other posts I have been able to link to another site but I received this photo via e-mail. I should have it available for you to link to very soon.

Dave

Van’s recently posted a Service Bulletin regarding the modification of RV-10 engine mounts. The problem with the engine mounts is that they will not accommodate certain variants of the venerable (I)O-540, A crossbar that runs near the induction sump interferes with certain models of cold air sumps such as those offered by Barrett Performance.

In the SB Van’s says that “it is the builders responsibility to assure that any NON-Lycoming engine (including ‘clones’) be dimensionally equal to that of the stock 260hp Lycoming (I)O-540.”

Van’s has always held firm on the insistence that 260hp be the limit for this aircraft and there have been some who have increased the performance of the (I)O-540 D4A5 engine through the addition if different ignition systems, higher compression pistons etc. I am unsure as to what the driving factor is for this close adherence to a horsepower rating. Is it weight and balance, VNE, risk of litigation?

It seems to me that the builder should have the unrestricted choice as to which power plant he/she puts in the aircraft. The rules under which we build these EXPERIMENTAL aircraft allow us to put any type of power plant in the aircraft as long as the installation meets acceptable building practices and standards.

It is the pilot who is controlling the higher horsepower engine via the throttle that keeps the aircraft under the VNE speed. It is the builder who compromises when it comes to weight and balance. The heavier engine up front will extort a price when it comes to the weight needed in the rear to balance the aircraft.

As for the litigation, I think that there have been too many instances where the spouse of a pilot/builder has brought a law suit as a result of an experimental aircraft crashing. Wasn’t that spouse in full awareness of the construction of the aircraft and the implicit risks involved? Maybe its me and I just don’t get it.

Van’s is doing it correctly when it comes to producing a kit aircraft. They should offer only one engine mount. The one for which they have done the testing prior to bringing the aircraft to market. Let the market produce the modified engine mount that supports other engines. Then let the builder do the verification testing in a 40 hour test schedule. That is what it is there for.

I am all for making modifications to aircraft. That is what this blog is dedicated to. We need to design test and bring innovative products and processes to help with the evolution of kit aircraft. We will modify them to meet a specific mission. The reality is that the mission is subtly different for every builder out there.

Dave

It is funny how you can have this perception as to how a product needs to be manufactured and then you talk to someone who offers up a completely different and better way to do it.

I had another look at my tail strobe mount ring the other day and was talking to an engineer that has experience in CNC and other manufacturing technologies. Here I was thinking that I would need to set up a bar of aluminum and have a 2 axis CNC milling machine mill the shape out. I would then take the remainder of the bar and simply cut the parts off from it using a band saw. This vision defaulted to my usual way of approaching the manufacture of things I design. High complexity and high cost.

My engineer acquaintance looked at the napkin that I was drawing on and said why don’t you just cut it out using a water jet cutter? DUHH!! Now there’s a good idea. This means that can get the parts cut out for a great deal less money and will therefor be able to pass the savings on to the people who are interested in it.

I should know in a couple of weeks where and when it will be available. I am working on getting a US distributor so that largest market is served well and won’t have to deal with the border and its shipping fees.

Happy Building

Dave

Many builders are talking about installing electric rudder trim. The RV-10 is a very capable cross country machine that could benefit from rudder trim during those long flights. The problem with a fixed rudder trim tab is that it performs best in a narrow range of speed. With the capabilities of the RVs in general and especially the RV-10 there is a need to vary the angle on the trim tab.

I initially heard about trim system that Vic Syracuse installed on the Matronics list. Vic did a very nice job of shoehorning a Mac servo into the rudder on his RV-10. I have heard that you can install this system after the rudder has been built. It takes some careful cutting and the installation of an inspection cover kit but it is definitely doable. The actual flying surface of the trim system is not all that big. It extends from the rudder trailing edge a little more than the width of half a piano hinge. It gives the rudder a more complex look with the control arm extending from the small fairing that protects the exit hole.

Vic did a great job of making it look like it was designed with the airframe. This is always the true test of the person designing a modification.

I’ll post some pictures below for you to get an idea of how it looks and functions. You should be able to click on them and you will go directly to Tim Olson’s site where the higher resolution photos are stored. Thanks Tim.

Have a great time today building and modifying your aircraft.

Dave

Hi there everyone. I would like to thank all of you who are tuning in to hear me talk about my favorite pass time. Modifying aircraft to make them more capable, more beautiful and more personal. I just came from my web statistics utility and I was pleasantly surprised at the increasing number of readers. Thank you. When I started this blog I was sure that I had an audience. I am consistently surprised whenever I check the page views.

I would like to ask that everyone out there who is reading this blog on a regular basis to please let one of your buddies know about the site. I would like to expand the readership to a broad base of pilots and owners. The more people we have reading means that there will be more and more input into the blog.

I would also like very much to hear about any kind of modification that you have made to your aircraft. It doesn’t have to be earth shattering or flashy. It just has to be something that you are passionate about. I will have it on the blog in a flash and you will have that 15 minutes of fame that you have always yearned for.

OK, enough about that stuff. Lets get into today’s topic.

Over the weekend I had the opportunity to work on a couple of things. First is Van’s wonderful, high quality, ready to install (NOT!!!!) fiberglass canopy. The second is a modification I’m making to address a weight and balance with the RV-10.

The RV-10 is a four place aircraft. This is an indisputable truth. As such, there has to be a large CG range to accommodate the range of loads from single pilot with full fuel to all seats occupied with baggage. Van’s built the compromise into the aircraft and in my opinion did a fairly good job. Every aircraft is a flying bundle of compromises.

It has been observed that the RV-10 that Van’s uses for demonstration flights usually has a bag of shot located in the baggage compartment when flying with only two pilots up front. The reason for this is that the CG is right up at the forward limit when in this configuration. It has been noted by a number of RV-10 pilots as well as Van’s itself that the aircraft tends to run short on elevator trim authority in this configuration.

Many pilots have resigned themselves to traveling with some weight in the baggage compartment when traveling light. I got to thinking about this and I just couldn’t resign myself to carrying around extra dead weight. At the same time I was reading about many pilots of RVs that have added wing tip tanks or extra cells in the leading edge of the wing. I’m not a big fan of adding extra tanks to the wing without having them re-tested.

So, one day I started thinking about putting in an auxiliary tank in the baggage compartment. Something that weighs in at about 60 to 70 pounds full would be ideal. The extra fuel weight would be beneficial when traveling with just the pilot and passenger. Something that I think I will be doing quite often.

I thought about my typical missions which will be flying the wife and kids to the cottage and using the plane to travel on business. When we are traveling as a family the tank stays empty. When I am traveling on business in an IFR environment the tank will be full.

Now, how do I do it? I decided that a tank that is in the baggage compartment would have to fit forward under the cross brace and up against the rear passenger seats. In this position, I would be able to tie the tank into the cross brace as well as the floor. I decided that there would be NO tank filling within the cabin so I designed the tank to be filled from the Right wing tank.

I initially was going to have the aux. tank filled from the Left tank. That is until I invited Tom Martin, one of my technical advisers to have a look at the concept drawings and diagrams. The first thing out of his mouth was, “Why the left tank?” I said ” I just picked it.” Tom said that because of the predominance of left hand turns in the landing pattern it would be wiser to have the ability to move fuel into and out of the right tank because it is the high tank when coming in to land. Most pilots will select the right wing tank in the pattern because they want the fuel at the pick-up when turning left.

I had to purchase an Andair fuel valve that had the AUX. position. I wanted to be able to feed the engine directly from the Aux. tank as well as have the ability to transfer in and out of it. The fuel lines run along the center tunnel up near the top and run all the way to a section of the tank that protrudes down through the floor.

I had to modify the baggage compartment floor to accommodate a removable panel that would allow access to an area under the floor where the dual transfer pumps, valves and plumbing are located. I want to be able to remove the tank easily for maintenance (15 to 30 minutes work) so I have incorporated shut off valves into the under floor plumbing as well.

This is the way I see the whole thing working. Normally, you would keep the tank full. I am going to be flying the plane solo a great deal so this is the best situation for weight and balance. If we are going to go on a trip where we are going to be loading the aircraft close to the gross weight , I will fly off the fuel from the aux. tank before the flight and we will proceed with the standard 60 gallons.

This thing is a work in progress. I have the fuel plumbing in from the valve to the floor rib at the front of the baggage compartment. The rest is on paper or is sitting on my work table waiting for my attention while I grind and file and sand the exceptional, high quality fiberglass components so that they will fit what is arguably one of the finest aluminum airframes offered in the marketplace.

I will have more commentary and some photos on this topic as I move further along.

Dave

I have been wondering what it might be like to put in a set of Precise Flight Speed brakes in my RV-10. I live in Southwestern Ontario Canada and it gets pretty cool here during the winter months. These speed brakes would let me create instant and controllable drag to get the airplane down quickly without having to shock cool the engine.

There seems to be lots of room in the bays between the wing ribs to install the two units and I imagine that it would be a fairly simple install when building either the standard or quick-build version of the wings. There would be a tremendous COOL factor as well.

I have often thought that it would also be of benefit when you are on the ground in high wind conditions. You could deploy them while taxiing to help control the aircraft better.

From what I have read there are a myriad of situations that would benefit from the use of speed brakes. Many pilots incorporate them into their checklists to ensure that they are used in a regular fashion. Most owners who install the Precise Flight system in their aircraft cannot understand why they didn’t do it sooner. Some even said that they should have put them in before other major upgrades, such is their utility.

There is a great AOPA article called “Lowdown on GO Down” that is very informative on this system as well as spoilers. I found a price on the Lancair website that show the speed brakes listed for US$ 3500.00. This is a pretty penny if you are building on a budget but so is the cost of a couple of “quicker than you anticipated” descents where you do some damage to your engine.

Here are a couple of pictures.

Dave

I came across an interesting throttle set-up installed in Scott Jackson’s RV. I didn’t see which model of RV he has but it’s a side-by-side model. It seems that there are a number of pilots out there that want this kind of arrangement because they have flown for the military.

I have always wondered what it would be like to operate the center control stick with my right hand. Having learned to fly in a Piper and then switching to Cessnas later on, I learned using my left hand on the yoke. It would be nice though to be able to control the aircraft with my dominant hand.

The more I look at Scott’s installation the more I like its simplicity. I think that I will look and see if there is room along the side of my RV-10 to install a second throttle. I will post Scott’s commentary along with some pictures.

Dave

” I’ve tried to keep it as simple as possible by making the left hand throttle connect to the center throttle right at the quadrant. This was possible by making the center-throttle lever extend below the pivot point so that it could be driven by, or drive, the left-hand throttle while the portion of it above the pivot was connected conventionally to the carburetor. Works well. Only problem to date has been a tiny bit of lost motion which I’m tracking down by bushing the pivot and clevis holes in the levers. Time will tell if the left-hand lever is too far aft-presently it’s right in line with the control stick when the stick is vertical. Since the pictures were taken, I’ve cut the left throttle lever shorter so the ex-military throttle grip almost touches the armrest.”

I have been watching in awe the accomplishments of a fellow Canadian as he designs and implements the installation of a turbocharged Subaru engine in his RV-10 project. Ross is the kind of guy that has the smarts and the where-with-all to pull of an engine conversion correctly.

He started in the game a few years ago with an RV-6. In it he installed a turbocharged Subaru EA-22. I was very impressed with the amount of detail and testing that he went through in validating his design and installation. You can see how he did it all in his RV-6A Build Log

Ross has a company that manufactures electronic ignition and fuel injection systems for the racing industry. As such, it only seemed fit that he adapted it to work in an airplane. It is simple and robust and flight proven. You can go to see his products at his Simple Digital Systems EFI home page.

After completing testing the RV-6A it seemed that Ross still had the building bug so he ordered a Van’s RV-10. I have watched his progress intently as he shares the same alternative engine bug that I have. I have especially enjoyed his development of a belly scoop where he houses the engine cooling radiator.

Ross has decided that the RV-10 needed more horsepower. To that effect he rounded up a twin turbo, Subaru EG33, six cylinder DOHC engine rated at 275 hp for takeoff. Isn’t that a mouth full. He has documented all of his fabrication and installation efforts in his RV-10 Build Log.

I would take the time to read very carefully all of the information on his site. there is a tremendous wealth of information available to the builder who is considering an alternative engine and it gives a true picture of the effort involved in creating your own firewall forward package.

Dave

Most people in the aviation community who have met me, either in person or on-line know that I am an alternative engine nut. From day one of my RV-10 project, I have been looking for an engine that would replace the prehistoric IO-540 that Van’s designed the airframe around.

As with most builders I ran into numerous roadblocks when it came to evaluating different engine options. One of the largest problems with the alternative engine market in general is the lack of a suitable firewall forward package. There aren’t many builders that want to put on the engineering hat as well.

Being the closet engineer that I am led me to start putting together a FWF package together for one of the engine / PSRU combinations that I thought would be perfect for the RV-10. The engine mount was the first piece in the puzzle.

I figured that it would be easier to start from scratch when building a new engine mount than to hack the existing one apart to modify it. It being already welded and heat relieved. I was able to get an example of an RV-10 engine mount lent to me by a fellow builder. From this we took measurements that gave us the dimensions of the mount points as well as the design of the structure that the nose gear is mounted to.

I took this information to a local aerospace MIL-Spec welding and fabrication shop. We made a fabrication jig and 2 initial units. This sub-mount is the perfect staring point for the builder who wants to install an alternative engine without having to hack apart the mount they get from Van’s. In fact you would be able to delete the mount from the Van’s Finish Kit to reduce costs.

The new sub-mount is made from the same material as the original and has been properly welded and heat treated. I think that there is are a number of individuals out there building RV-10s that are looking into alternative engines who might be interested in this product it should save them some time.

As happens in the pursuit of alternative engines for aircraft, I ran into too many roadblocks at least on the engine that I was pursuing at the time. I am currently waiting on a very new engine technology to mature in hopes that I will be able to utilize it in a totally new aircraft engine design. It will be designed to exactly fit into the space utilized by current engines and will attach to the existing mount so I have no need for these initial units.

I have 2 of the initial units available and more can be made with some notice. Here are a few pictures of them. You can contact me at davehertner@kitaircraftmods.com if you are interested in acquiring one of these for your project.

Dave

I found what I think is probably the coolest positions lights in the whole universe. Jeff Bordelon has taken some very powerful LED lights and embedded them in a plastic housing that is highly mirrored. It reminds me of the tail lights on many vehicles today.

Here is a couple of photos of the housing that holds the LEDs

What strikes me about this design is its efficient use of actual lighting to do the job. Usually you see this array of LED lights that are attached to a visible circuit board. I find that this is somewhat unfinished looking. This is the first LED set-up that I think has a purposeful design. What a bonus that the inclusion of mirroring adds to the overall efficiency.

Here are a couple of pictures of Chad Jensen’s wing tips with Jeff’s LEDs installed.

I would like to say bravo to Jeff for his fine work. He is offering these for sale on his web site http://www.jeffsrv-7a.com I think that I am going to put these in my RV-10 and there is no doubt that they would look great in your airplane.

Keep building!!

Dave