Major Decision Points


Instead of having all of my decisions only appearing chronologically throughout this blog, I will attempt to catalog them here. Hopefully, this will be a concise summary of the big decisions.

1. Kit aircraft vs conventional?

This is an easy one. I’ve flown several conventional GA aircraft. Your typical pipers and cessnas. For the performance I want, they are substantially more expensive. When comparing a new certificated aircraft to an experimental you’ll discover that the experimental is substantially cheaper. When you consider the performance of many experimental planes, such as the Van’s line of aircraft, the difference is even more substantial. Many kit manufacturers have excellent safety ratings and robust networks of builders. An aircraft must fit a mission. A Cessna 172 is fantastic if you want nothing to do with maintenance and your mission is flying slow in level flight from point A to point B. If you want greater speed, higher climb rates, and aerobatic performance you have to look elsewhere.

2. Which manufacturer?

Van’s Aircraft has produced more kit aircraft than any other company because Van’s offers some of the best all around kit aircraft in the world. Van’s RVs have almost become ubiquitous in the experimental community. This popularity provides a great network of support and ensures continued parts availability. RV builders are a welcoming, supportive, and entertaining group. And so, choosing Van’s Aircraft is a no-brainer. Van’s RV’s are awesome, and are only outdone by the community around them.

3. Which model?
First let me begin, by listing out the capabilities I want.

1. Must be fully aerobatic

2. Capable of aerobatics with a passenger

3. IFR capable and able to do cross country flights with a limited amount of baggage.

At first glance only two models meet these demands. The RV-7 and the RV-8. At this point I’m fairly set on center-line tandem seating, but I am open minded to the 7. The RV-4 is also still on the list. While it doesn’t necessarily meet all of my requirements, it is the best handling and most economical to build. (My wife and I are both light and I think with the proper CG planning and a CS prop up front, aerobatics could be performed with the two of us as passengers. I’m 5’6, 140 lbs and my wife is 5’5″, 115 lbs) Looks like the 8 is probably the best choice but I really hate to sacrifice even a small amount of handling capability.

I love both the RV-7 and RV-8, but my focus is on the pilot, not the passenger, so for me it will be an RV-8. This puts the throttle on the correct side, and the pilot where he should be; on the centerline!

4. Tailwheel or Nosewheel?

I do not have my tailwheel endorsement, and I’ve never flown in a tailwheel aircraft. (No longer true, Mike Bullock took my for my first tail dragger flight) That being said, I absolutely want my plane to be a taildragger. For starters, I think nose wheel variants of the Van’s line are rather ugly. The tricycle gear completely destroys the beautiful lines and retro-fighter appearance. I want to improve my piloting skill as well and this is an excellent opportunity. While tailwheels can be trickier to land because the wheels are forward of the center of gravity, they are better suited for soft field landings.

5. Kit Options

Empennage: For the empennage there is only one kit option; electric elevator trim, and I’m getting it. A properly trimmed aircraft is essential and I want to design my controls to maximize HOTAS. I plan to use an infinity stick grip.

Wings: Capacitive or float type fuel sensors? I chose capacitive sensors. I did quite a lot of research. Some people report that the capacitive sensors are less reliable,mothers that the float type are. I’m generally inclined to trust capacitive sensor more. Regardless everyone agrees that the capacitive sensors are more accurate (provided of course that you don’t switch fuel types).  There are more options on the wings than meets the eye.  How to run conduit?  What lights and where?  Fuel tank caps?  Flop tubes?  I’ve chosen to run two conduit holes per the recommendations made by Van’s and I’ve used the standard conduit sold by them.  I returned the standard fuel tank caps for the deluxe locking caps.  The standard caps are just sub-par IMHO.  Additionally, I’ve chosen to install two flop tubes.  I see no reason why I should have to pick one take for aerobatics or inverted maneuvers.  For $30 bucks its money well spent to make sure I have fuel flow regardless of the selected tanks.  For lighting, I have not yet decided what light system I will use, however I have decided that my landing lights will be located on the leading edge.  Some don’t like the look of the lights on the leading edge and prefer only the wingtip landing lights which offer a significant reduction in performance, particularly with regards to taxiing.  I always value performance over appearance.  I plan to fly at night and I want to have the best lighting possible.  Furthermore, I don’t think they look any worse than the wingtip lights.

Fuselage: First, I decided to do my fuselage as a quick build. This saves approximately 400 hours of labor, which is a significant chunk of time. I chose to install ground adjustable rudder pedals. It will be an extremely rare event that someone other than me flies from the front seat! In addition to the ground adjustable rudder pedals, I’m installing the rear seat rudder pedals.

Finishing Kit: I excluded many items from the finishing kit. I was able to find a local builder who had multiple parts for sale, to include the stock Van’s cowling. Additionally, I left off the parts for the Show Planes fastback, the tires, and a few other odds and ends. The canopy is the stock Van’s canopy.

6. Power-plant Options

Fuel injected or carburetor-ed? 160, 180, or 200HP? Lycoming or clone? New or used? I would love the 200HP OEM Lycoming, but it is significantly more expensive than the 180HP engine. I’m not sure that the increase in performance of the 200HP is worth the extra cost. Horsepower aside, I do want a fuel injected engine. From reading several VAF threads and other websites, the fuel injected engines seem to enjoy significantly better fuel economy and do not suffer from carburetor icing. The downside is a more complex system and increased cost. I like this option, but I’m sure I can be easily convinced of the merits of the other available options. A completely rebuilt or recently overhauled engine may offer significant savings. I definitely do NOT have any interest in developing something akin to the RV Super 8. Nor am I interested in any motor-vehicle engine conversions… IMHO that is more trouble and risk than the cost savings are worth.

Fuel System:  This is a big area with many many variations possible and just as many potential ramifications.  Currently, GA generally uses 100LL fuel.  But, under pressure due to prices and environmental concerns updated AVGAS development is underway.  More important however, is the wallet to airplane performance ratio.  MOGAS is available for significantly cheaper prices.  MOGAS is not what you find at your local pump.  Auto gas usually contains ethanol which can be incompatible with aviation fuel systems.  But consider these generic numbers.  AVGAS (100LL) is currently selling for $5.81.  MOGAS (ethanol free) is selling for $4.20, and premium auto fuel (93 Octane with ethanol) is $4.00.  Lets assume 200 hours of flight at a burn of 8gph.  That works out to $9,296 for the AVGAS, $6720 for the MOGAS, and $6400 for the autogas.  The MOGAS represents a huge amount of savings.  In fact, if you multiply those savings out to a typical TBO of 2000 hours, you can easily afford a complete engine overhaul and an upgrade.  So what am I going to do? Well, the short answer is I’m going to wait. The next couple of years may see some changes in the availability of non-ethanol auto fuel and fuel systems that are ethanol compliant. In the end, I want to design my engine and my fuel system to be compliant with all three types of fuel and have the maximum allowable horsepower.  I’d rather sacrifice a little horsepower, and a little extra time and expense in the fuel system in return for what amounts to savings in the 10s of thousands of dollars over the lifetime of the aircraft.  In the end that will mean more flying for me!

So far here are my decisions:

  1. Parallel valve or Angle Valve (180HP or 200HP): Leaning towards a parallel valve from a clone manufacturer with slightly higher compression to get me closer to 200HP without the weight. 12/01/2012: I will most likely build or have built a kit engine. Jack Savage’s parallel valve IO-360 puts out 191HP, and while not cheap, offered significant savings over the more powerful and heavier 200HP. Another major contender is a IO-375, made by Aerosport Power, that produces 195 or 205HP. The IO-375 is also a great value. Another potential engine is the IO-390 by Barrett Precision Engines producing 210 HP.
  2. Carborated or Fuel Injection: Fuel Injected for negative G aerobatics, and a host of other important reasons like… Carb icing. I will absolutely be getting a fuel injected engine.
  3. Rebuilt, new, or very low hour: Leaning towards a clone rebuild or kit… we’ll see.
  4. Horizontal or Vertical induction: Prefer no snorkel, so horizontal if able. Plus my understanding is that fits with Van’s drawings FF.
  5. Flop tubes must be placed in fuel tanks for sustained inverted flight
  6. Inverted oil system to maintain oil pressure during negative g maneuvers is a possibility
  7. Hollow crank for CS prop
  8. Oil accumulator

7. Electrical and Avionics Options

Electrical Power System: Not many decisions here thus far.  I will need incorporate some level of redundancy for electrical power.  I really like the look of the Vertical Power VP-X Pro, but I’m not sure that I can justify the cost.  I’m a fan of its integration with multiple EFIS options, and its smart breakers.  For instance, it will automatically disable the starter after start, disable the flaps above a certain airspeed, or even adjust the rate of trim actuation based on speed. I’m a firm believer in ECB’s and the dual independent bus is a great built in redundancy.  Coupled with a direct backup system for the absolutely most essential systems, it is very easy to create, wire, and fully control a complex and easily modifiable system.  The design and implementation of the electrical system, avionics and “user experience” in the cockpit is by far the most exciting part of the build for me and I can’t wait to get started.

Avionics: I would like the final aircraft to be IFR capable with equipment redundancy beyond FAR minimum requirements. My primary considerations will be ensuring I have the capabilities I want as cost effectively as possible. Originally I was thinking to put steam gauges in. After a lot of reading and researching, I’ve decided to do a glass cockpit. For the better part of the 20th century avionics changed very little. In the last 10 years that has changed. Avionics are advancing at a rapid rate. Many avionic suites feel old just a few years later. Resale value would be negatively impacted by using steam gauges, and 5 years (or more) from now, the premier glass cockpits of today will be substantially cheaper. I’m really open to suggestions regarding avionics. As I progress I will attempt to clearly line out my options here.

8. Prop & Governor

Constant speed or fixed pitch? Type of prop? Since I do want to be IFR capable, I do not want a wooden prop. I’m definitely leaning towards a constant speed system for a couple of reasons. Obviously the better performance is the first, and secondly, I have more hours operating a constant speed prop than I do a fixed pitch. Again, I’m fairly open on this one and luckily I have quite awhile before I need to make the decision. More important to me than the prop itself is the prop governor system. Aerobatic aircraft will be better suited with a counter-weighted system that will cause the prop to go full course thereby reducing RPM and preventing an over speed in the event of an oil pressure loss. The downside of this system is a substantial increase in weight, cost, and complexity. My highest priority for the RV-8 is performance, specifically aerobatic performance. That being said, I do not have any desire to do aerobatics competitively, nor am I super interested in negative g advanced maneuvers. The majority of my aerobatics will be rolls, loops, half 8’s…. positive g maneuvers. However, I do want the ability to perform more complex maneuvers with minimal risk to myself or the aircraft.

9. Priming, Paint and Finishing

Priming. This is a source of never ending debate, and everyone has a differing opinion on the subject. Discussion of priming invokes such heated debates that it has almost become a tabboo to discuss (which is ridiculous). I’ve decided to prime all interior parts with AKZO two part epoxy primer. I’ve included the datasheet among the reference documents on this site. Here’s my priming process (which I’ve basically stolen from Mike at www.rvplane.com):

  1. ETCH. Some people will use an acid etch solution such as alumiprep. I simply scuff all surfaces with a scotchbrite pad. This is deemed sufficient preparation by AKZO staff, and it works well in my experience. Its also quicker and easier than an acid etch.
  2. CLEAN. There are many methods here. Many builders clean with water, then etch, then clean again with a solvent and so on. I clean the surface first with water. I use a rag and a hose. After the parts have dried I use acetone to remove all other contaminates. I wear latex gloves for handling the parts beginning with the etching process.
  3. PRIME. Mix the AKZO 50/50 and allow it to set for 30 min. Load up your spray gun, make the necessary adjustments and always perform a test spray on a non aircraft part first. Apply a thin even coat of primer.
  4. CLEANUP. I rinse the cup with a solvent and then run some solvent through the gun to remove as much primer as possible. I remove the two nozzle pieces and soak them in solvent overnight, and do a basic wipedown of the entire gun. DONE!

Why prime at all? Two reasons. First and foremost to protect your investment against corrosion especially in humid climates (I live in the Mid-Atlantic). Secondly, primed aircraft have a higher resale value, which again protects my investment. So, why AKZO? There is little dispute that AKZO offers some of the best corrosion protection available. The debate then, centers on the necessity, cost and time of its application. Is the added protection of AKZO worth the extra time and money over a self-etching primer in a can? I believe it is, and here’s why. Once the decision is made to prime the aircraft, time and money is committed. (As well as weight) For me, choosing a priming system is about optimization. I want the maximum protection for the minimum effort. This is why my process is only four steps, does not include alumiprep, and skips the alodining process altogether. Its not the maximum protection available, but its definitely better than others (whose protection may very well be more than sufficient) and for only a marginal increase in effort. BOTTOM LINE: There are many products and processes that offer varying degrees of protection for your aircraft, and in choosing which is best for you, you must consider a variety of factors. IMHO the process I’ve chosen represents the optimization of maximum protection for minimum effort.

Paint. RV’s are sort of like sports cars and they should look like it. It annoys me when people paint general aviation aircraft in colors that do not increase visibility. We’re not trying to be tactical here. The big sky little plane theory has never worked, and I want people to see me. RVs are also not Cessnas… they are sportier and should look it. Be creative, be bold.

6/8/2013: I’ve made two decision regarding paint. One, I will definitely paint the plane myself. Two, and because I will be painting the plane myself, I plan to complete the paint prior to the first flight and complete assembly. My Uncle Joe offered to help me paint (he’s got all the tools and way more experience than me)… Although I’m not sure he realized I’m totally planning on taking him up on that offer!

Finishing. Not many decisions here yet. More to come.

10. Modifications & Miscellaneous Items

Canopy Options: (I have pilfered the photos below from the internet and hope the original owners do not mind)

Standard Slider– This is the design that comes standard from Van’s. Large canopy slider with the intersection and the roll bar towards the front at the start of the instrument panel. Advantages: Standard, no additional cost, no additional work, allows for taxing with slider open, fixed windshield. Disadvantages: Reduced forward visibility (particularly annoying for formation flight), harder to access instrument panel.

Standard Tip-Over– Modify the above design to tip over vice slide back thereby eliminating the forward intersection / roll bar and increasing forward visibility. Downside, reduced “cool fighter factor” on taxi, and reduced airflow on the ground.

Fastback Slider– The fastback modification adds a turtle back behind the aft cockpit for a faster appearance. There is some data to indicate that a fastback is slightly faster. Most of that data is from an RV-4. The intersection is at the same location.

Fastback Tip-Over– This is my favored design. The RV-4 is a better looking airplane. The cowling is more aggressive looking and for some reason the slider canopy makes the RV-8 look long and awkward. The fast back brings a much more aggressive look to the RV-8. The detractors of a tip-over primarily complain about not having the “fighter” feel of taxing with the canopy open. I think we spend 90% of our time flying, and 10% of our time taxing. If the choice is forward visibility or comfort and cool factor on the ground, I choose forward visibility. I’ll gain cool points with the fastback. I intend to install the Showplanes fastback mod with tip-over canopy. I will most likely install a roll bar similar to the RV-4. More to follow on the roll bar later.