N727RT: Project Notebook

  Intro: Build Options

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Although the Lancair ES is a relatively simple, mature, and  complete kit, the builder is still faced with a number of design decisions regarding options, equipment, and potential enhancements.  These include:

• Engine (Aircraft vs Alternative/Auto)
• Engine (Normally Aspirated vs Turbocharged)
• Propeller
• Pressurized vs Un-Pressurized:
• One Door vs Two Doors:
• Extended Fuel:
• DeIcing:
• Brakes:
• Build Assistance:
• Avionics
• 12 vs 24 Volt Electrical System
• Other Options & Design Considerations

Click the items above to jump to the related discussion below or continue to browse sequentially.  Additional (less significant) options and design/build decisions are covered in the details of the Construction Notes pages of this site.

Engines (Aircraft vs Alternative/Auto):

After purchasing the kit, selecting and buying an engine is perhaps the next largest and/or most significant decision facing an amateur builder.  It is typically the single largest price item (unless you buy a complete professionally made glass panel instrumentation package) and it can have significant time to build, testing, performance, and safety impacts as well.

The Lancair kits (ES, IV, and Legacy) are designed for and include a motor mount for the TCM (Teledyne Continental Motors) family of aircraft engines, primarily the IO360, IO550 or TSIO550.  These are "old school" aviation engines - big bore, air cooled, opposed 6 cylinder, direct drive engines, designed to operate around 2700 max rpm.  They are capable across a wide range of operating conditions, have proven to be very reliable (when operated within limits), are popular enough such that having them serviced is relatively easy, and are relatively efficient (depending on your perspective).  However, they are very expensive.  For comparison, a new General Motors LS2 400 HP corvette motor (in a crate) is less than $10,000.  Whereas, a new 30 HP TCM IO-550 is approximately $50,000 and a new 350 HP TSIO-550 is over $70,000.

Based on the potential cost savings, it is naturally tempting to look for opportunities to re-purpose a high volume (and thus relatively low cost) automotive style engine in an airplane.  Auto engines are also typically water/liquid cooled (versus air cooled aircraft engines), which create more stable operating conditions, and thus allow tighter clearances, high compression rations, and potential economy improvements.  Furthermore, automotive style electronic fuel injection engine control units make starting easy and help ensure smooth operation.

However, there are significant challenges along with the pain/risks of going-it-alone on an alternative engine.  The challenges include: 1) reducing the rpm from the 6000'ish max car engine rpm to the 3000'ish max propeller rpm;  2) devising an efficient way to incorporate a radiator to accommodate the liquid cooling requirements,  3) working to minimize the overall installed weight, and  4) working out the inherent misalignment between the crank and propeller centerlines.  Availability of insurance and maintenance is also alternative engine considerations/challenges.  Despite these challenges, several builders have built and flown Lancairs with alternative/auto style engines, and so it is possible.

A couple builders are installing rotary engines which help avoid some of the typical alternative/auto engine issues (gear reduction, weight, and alignment) and offer potential reliability advantages based on having fewer moving parts.  However, these projects are highly experimental (personal opinion) and still include a number of challenges include the efficient radiator issue, insurability, and maintenance.

As an automotive guy, and engineer living in Detroit, I was tempted to seriously consider some of these alternatives.  However, after spending several days/weeks reading through past messages/posts on several of the popular amateur builder website forums, I decided there were plenty of issues that naturally arise (without adding more) and that part of the value of the kit approach is the insights and experiences gained from other/prior builders.  Thus, I could not come to a conclusion that it would be better to add more issues and abandon the collective experiences of other builders by choosing an alternative/auto engine path (even if it offered potentially significant savings).

Lycoming vs TCM :  Lycoming is TCM's primary competitor in the light aircraft engine business.  From an overview perspective, both companies offer similar engines with similar performance, weight, and reliability specifications.  Anecdotally, TCM engines are know to have top end cylinder wear issues, especially with valve guides.  Similarly, Lycoming seems to have had more that it's share of crankshaft problems resulting in numerous AD's (mandatory airworthiness directives).

Conclusion / Decison:  Given that the Lancair kits are supplied with a TCM ready motor mount and that most builders (80%+) install TCM engines, I've decided to following the group go with a TCM engine.

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Engines (Normally Aspirated vs Turbocharged):

TCM offers its 550 cubic inch engine in either a Normally Aspirated (IO-550) or Turbocharged (TSIO-550) model.  The advantage of the turbocharged model is that is makes 40 more horsepower+/- and can deliver full horsepower even at high altitudes.  Whereas, the normally aspirated engines make progressively less HP as you climb due to the thinning of the atmosphere.  The disadvantages of the TSIO550 are cost, weight, complexity, and fuel economy.

In attempting to compare the advantages of increased HP and performance at altitude (TSIO550) versus cost, weight, and economy (IO550) it is relevant to review the reasons for wanting to fly higher:

• Performance/speed: The higher you fly the thinner the air and thus the less drag, and thus the more speed (and range).  An airplane with a turbocharged engine (which continues to make full/cruise HP even in thin air), can travel over 30% faster at 20,000 ft than at sea level.
   

• Economy:  The aircraft (above) going 30% faster at 20,000 ft will have the same fuel burn (per hour) as the one at sea level going 30% slower, and will thus go 30% further on the same fuel quantity.
   

• Safety:  The higher you fly, the further you can glide in a potential emergency.  From 25,000 ft, an Lancair ES can glide up to (or beyond) 50 miles without power.
   

• Wind:  When the wind is going the right way (with you), winds up around 20,000 ft can often be 50mph+/- (sometimes near or over 100mph), creating an added free increase in speed, range, and economy.  When it's a headwind - stay low.
   

• Weather:  Large thunderstorms can rise 30,000-40,000 ft, higher than small aircraft (and some large aircraft) can fly and thus need to be avoided in all situations.  However, typical low clouds, light rain, and snow can typically be topped at 15,000 - 20,000ft, creating opportunities for clear-air cross-country legs, even with marginal/nuisance weather below.
   

• Terrain:  In the western US, the mountains rise to 12,000+ feet.  Due to sometimes turbulent winds in/over the mountains, it is best to clear then by as much as possible - requiring flight well up into the oxygen required altitudes (above 12,500ft).

For the advantages outlined above, I've opted for the turbocharged engine (TSIO-550).

Furthermore, this configuration (a Lancair ES with a TSIO-550) also helps reduce the performance gap between the ES (fixed gear) and the faster Lancair IV (with a retractable gear).  While the math/performance doesn't truly work out exactly, an ES with a TSIO-550 might be thought to perform similar to a IV with a normal IO-550.  Given similar cost premiums between an ES vs a IV and an IO-550 vs a TSIO-550,  one could theoretically make a decision between turbocharging and/or a retractable gear for similar cost and with similar performance.  In that case, I personally would chose the safer (but less sexy) TSIO-550 with a fixed gear scenario, which is essentially what I am building.

Conclusion / Decision:  TSIO-550.  Note: Lancair offers two cowls for the ES.  The TSIO-550 engine cowl is slightly larger to accommodate the turbochargers and has slightly larger air inlets for provide extra cooling.

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Propeller:

Generally, the propeller decision is not as critical nor significant as the engine decision, but is an area often debated amongst builders and pilots, especially when attempting to compare performance.  There are three primary manufactures of propellers for the ES: Hartzel, MT, and AeroComp.  Additionally, since all propellers for aircraft like the ES incorporate a variable pitch blade mechanism, a discussion of the various pitch systems is warranted.

Hartzel has traditionally been the most popular and focuses on aluminum bladed props.  While they have recently announced a new composite prop, it is not yet available.  They primarily make props for certified (production) aircraft, which is viewed as favorable by the FAA, and thus typically results in lower required flight test hours.  Based on the limited data/facts available, Hartzel props do seem to be 1-2 knots faster than the others, with equal or better climb rates.

MT is a large propeller company from Germany, that focuses on high-tech composite props, which incorporate a wood core.  Like Hartzel, MT makes props for the certified (production) aircraft, which must pass the FAA's stringent certification testing requirements, including props for large, high HP turbo prop aircraft.  Anecdotally, MT props are known to run smoother and quieter, due in part to the composite structure and wood core.  This is especially true of the 4 blade props which they offer.  MT props also have the advantage of being lighter.  MT also offers a "counterweighted" version/option, which results in better glide performance.

AeroComp is a newer propeller company, that focuses on composite propellers for the amature/experimental market.  Based on limited data/facts available, the aero comp props for the Lancair ES and IV's are thought to be 1-2 knots slower than the Hartzel or MT.  However, good comparative performance data is scarce and test results on other (smaller) planes have varied.  Aerocomp's strong point is the advanced method used to secure the blades to the hub.  Aerocomp's largest propeller are sized for 300-350 HP, which puts a TSIO-550 at the top of their range.

Another consideration in choosing a propeller is the variable pitch mechanism.  The most common/traditional system is based on a blade which rests in the low pitch (flat) condition (based on a spring in the hub).  Then, an engine governor uses oil pressure to adjust (increase) the pitch to maintain a selected engine RPM via a actuator/piston in the propeller hub.  Hense, this arrangement is commonly called a "constant speed prop".  The advantage of this system is it's simplicity and the fact that with a governor or oil pressure loss the prop will automatically return to the low pitch position which is safe for most all flight conditions.  The disadvantage is that in the event of an engine failure, the prop will also return to the low pitch position, which creates the most drag and hence the least gliding range.

The other common type of variable pitch mechanism is a feathering prop, which is primarily used on twin engine aircraft.  A feathering propeller essentially works exactly opposite from a normal (constant speed prop), in that the propeller normally rests in the high pitch condition, and the governor uses oil pressure to adjust (decrease) the pitch to maintain a selected engine RPM (this is also a constant speed scenario so the names can be a bit confusing).  A feathering prop has the added feature that the high pitch position is essentially "in-line or smooth" to the direction of flight - known as "feathered", which results in very little drag if/when an engine fails.  This is good for ongoing flight in a twin and/or for maximizing glide distance.  The disadvantage is that is that if the engine is working, but the governor or oil pressure pitch system fails, that the prop will automatically go to the high pitch (feathered) condition, which is otherwise unsafe for flight as no thrust is created.

A third and less common type of pitch mechanism is a hybrid of the two, commonly known as a "counterweighted" prop.   A counterweighted pro works like a feathering prop in that it rests at the high pitch position and returns there in the event of an engine, governor, or oil pressure failure, which allows for the best glide performance.  However, the high pitch position is limited so that the propeller does not fully feather.  Thus, if only the governor or prop oil pressure system fails (and the engine is still running) then some thrust (for flight) is still available.  This arrangement offers some of the advantages of both other systems.

Conclusion / Decision:  MT Counterweighted, 4 Blade with Deice Heat pads

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Pressurized vs Un-Pressurized:

Lancair offers the ES in both a std (unpressurized) model and a pressurized version.  The primary advantage of a pressurized aircraft is that it allows flight at higher altitudes without the need for supplemental oxygen (which is otherwise required above 12,500 ft). The disadvantages are added cost, weight, space, complexity, and efficiency.

Why is oxygen required above 12,500 ft? At sea level, normal air pressure (density) is approximately 14.7 psi.  The higher you fly the thinner (less dense) the atmosphere becomes, such that at 20,000 ft the normal air pressure (density) has dropped approximately 50% to around 7 psi.  As the air pressure (density) drops so does the amount of oxygen inhaled when you take a breath. A average person can perform quite normally up to altitudes of around 10,000 ft +/- (unless you're a sherpa, heavy smoker, or trying to run a marathon up there).  As you continue climb beyond that, the lack of oxygen creates a medical condition know as "hypoxia" and causes a reduction in cognitive and motor skills until eventually you become unconscious.  Down around 10,000 ft, initial hypoxia effects normally develop very slowly and are not in themselves very dangerous.  However, up around 20,000 ft a average person may only have 10-15 minutes of useful consciousness.  At 40,000 ft it's down to under 30 seconds! The preventative remedy for hypoxia is supplemental oxygen, which can delay the effect of hypoxia due to low atmospheric pressure up beyond 30,000 ft +/-.  In an un-pressurized aircraft, the inside and outside air pressure is the same.  Thus, the FAA generally requires that pilots (of un-pressurized aircraft) breath supplemental oxygen above 12,500 ft.  This is normally accomplished with a mask (or nose canulla) and an on-board oxygen tank. Supplemental oxygen is not normally required in a pressurized aircraft, since the air pressure in the cabin is maintained at a pressure similar to altitudes below 10,000 ft.  However, pressurizing an aircraft is a complex design challenge with selected tradeoffs: Even a few psi of pressure can create very large stress forces when applied over a big area like an aircraft fuselage.  Thus, the fuselage has to be made stronger (i.e. heavier). All openings in the fuselage for wiring, controls, etc have to be (nearly) air tight (i.e. more building and maintenance work). The cabin mush be sealed-off from the rest of the (unpressurized portion) plane.  In the ES this means that the baggage compartment is seperated by a solid rear pressure bulkhead and normally no longer accessible from the rear seats, which otherwise normally fold down (i.e. less useable space). A pressurization controller is required to regulate the cabin pressure and to constantly exchange fresh air for exhausted stale air (more cost / complexity). A source of pressurized air is need to feed the cabin.  This is normally bled from the engine turbo charges and thus robs some performance and/or economy (minimal). Since the turbo is the source of the pressurized air for the cabin and the turbo air is warm, an air conditioning system is often required/desirable with a pressurized system (adding more cost, weight, space, and complexity).

I do plan on flying above 12,500ft regularity to take advantage of the speed, efficiency, safety, wind, and weather advantages.  However, since I primarily live and travel in the eastern US, high altitude and/or terrain avoidance (above 12,500ft) is rarely "required".  I have used a portable oxygen systems in my current plane and do not view it as a significant inconvenience.  In fact, I've found the oxygen helps you feel awake and refreshed after the flight.  The primary disadvantages of on-board oxygen are:

1. The hoses (which can be minimized with a built-in system)

2. The mask (which can be minimized with a nose canula system)

3. Ensuring an adequate on-board O2 supply  (which can be accomplished with a large tank - enough for long round trip missions, and through the use of an economizer which only uses/delivers oxygen during your inhale cycle.)

4. The cost/inconvenience of refilling (which can be minimized with a refilling station in my hanger)

Conclusion / Decision: Thus, while pressurization does offer some convenience advantages, I feel they are out weighted by the cost, weight, space, and complexity disadvantages.  Additionally, I do not view supplemental oxygen as being necessarily inconvenient if designed and used appropriately.

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One Door vs Two Doors:

Lancair offers the ES in a standard (one pilot door) and a optional two door model.  The two door model offers added convenience for the co-pilot and perhaps some marginal added egress safety in a potential emergency.  The disadvantage to having two doors is weight, build complexity, overall fuselage strength (which is reduced by the 2nd door opening), and cost.  Additionally the two door option is relatively new and there is little collective builder experience with it.

To put the decision in proper perspective it should be noted that many small aircraft only have one door as is evidenced by the many Piper and Mooney models that traditionally and still today are offered with only one door.  Consider also that many cabin class twin engine planes and most popular biz jets only have one door.

Conclusion / Decision: One Door

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Extended Fuel:

The main fuel tanks in the ES (and other Lancair models) are integral to the wings (known as a wet wing).  In this design, the wing spar, ribs, and skin form the sides of the fuel tank and are coated with a fuel impervious sealer.  The standard ES kit comes with wing tanks configured to hold approx 95 gallons of fuel, all in front of the main spar which is located at the mid-point of the wing chord.  As an option, the fuel capacity can be increase to approximately 110 gals by including an additional partial wing bay in the tank.

In reviewing pictures of the wing design/structure (prior to taking delivery and starting construction), it seemed that the limiting factor to added fuel capacity beyond 110gal, was the routing of the aileron control rods in the wing.  Whereas, if you could enclose the aileron controls, you could wet yet another wing bay with fuel for a total capacity of approx 125 gals.  At that point, all but the outermost wing bay is wetted with fuel.

Wetting the last bay would also be possible, but that places the fuel weight pretty far outward and the wing is very thin at the tip making it more difficult to get a nozzle far enough in so as to prevent splashing during filling.  Additionally the last wing bay normally provides access for things like the heated pitot tube, AOA sensor port, and optionally a navigation antenna.

Thus, while at builders assist, I built enclosures for the aileron control rods, and added one additional fuel bay for a total of approximately 125 gals (in front of the main spar).

I reviewing the wing design/structure, I also noticed that the first three bays behind the main spar were not otherwise used for anything and didn't provide access to anything.  By turning them into additional auxiliary fuel tanks, total capacity could be increased another 25'ish gallons (12 gals +/- each side).  This is not a normal "option" offered by Lancair.

Because I am also interested in incorporating a TKS weeping wing glycol anti-icing system into my ES (if/when it is offered for an ES by TKS), I'll need a tank to store the glycol fluid.  One of these rear aux tanks would work nicely (one side).

Conclusion / Decision:  Enclose the aileron control rods and extend the normal ES fuel tanks to 125 gals.  Also seal the first three aft bays as tanks for an additional 25'ish gals which could later be used for fuel or as TKS glycol tanks.

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DeIcing:

The build-up of ice on an aircraft wings, prop, windshield, and/or other surfaces can create a significant safety of flight issue.  Ice buildups (even a thin frosting) can significantly degrade aerodynamic properties (lift) and result in poor performance and/or loss of control.  Ice can form when flying through rain or clouds (visible moisture) when the outside air temperature is around or below 32F.  Given the cold wet weather that is typical in Michigan for 4-6 months of the year, ice protection is a relevant consideration.

However, use of deicing systems for light aircraft is a controversial topic among many pilots.  To make a system that is 99.9%+ effective and failsafe is a formidable challenge due in part to the variety of potential ice phenomenon/magnitude.  The heart of the debate is whether a partially effective system is better than no system.  Certainly the debate "high ground" is that the only safe place for a light aircraft during icing conditions is on the ground.  However, it also seems reasonable to debate that "some protection", regardless of it's lack of universal effectiveness would be better than nothing during an inadvertent icing encounter.

For a good article on deicing goto the AOPA SafetyAdvisor at: www.aopa.org/asf/publications/sa22.pdf

Commercial and biz jets use heated bleed air from the jet engines to heat the leading edges of the wings where ice normally first forms.  Obviously that approach is not possible with a light piston engine aircraft.  Rather, the 5 systems/approaches below are commonly used.

1. Leading edge pneumatic boots have been used for many years on high performance twins.  They work by inflating and breaking up ice after it starts to form.  Periodic cycling is needed to keep the surfaces clear.  The system is proven and works well under normal conditions.
   
   The disadvantages are that it is not 100% effective, as an ice bridge can form over the boot, which is then unaffected during inflation, the system typically requires some level of pilot supervision/workload, the boots wear with time and can fail and/or need to be replaced, and the boots add drag during normal operation.  I do not believe boots are available for an ES, although some could likely be fabricated or retrofit.  Given the disadvantages, I am not a fan of boots.
    

2. The TKS weeping wing glycol system/approach is not new, but has gained popularity recently.  The system entails thin porous panels which are added to the leading edge of the wings and then weep glycol when engaged to prevent ice from forming/sticking to the wing.  Since the glycol runs-back, the entire wing surface is effective protected.  A full TKS system includes glycol panels for the tail surfaces and a glycol slinger ring for the propeller.  The spray from the prop tends to protect the rest of the fuselage and windshield from ice also.  An added benefit of the wing panels is that cycling the system helps remove bugs when needed during the summer.
   
   The disadvantage is that the system uses the glycol, so an an board tank and frequent refilling is necessary, adding weight and inconvenience.  A typical tank is 5-7 gallons (~50 lbs full) and can last 2-3 hrs +/-.  Also to make the system 99.9% reliable requires dual pumps etc.  Unfortunately, TKS does not yet make panels to match the ES wings.  Also the panels are sometimes fed from the rear (depending on the application).  However, the standard ES wing has an electrical conduit which runs through the leading edge of the wing and thus might impinge on the ability to easily add TKS panels. 
   
   For more information visit Aerospace Systems and Technologies at: www.weepingwings.com
    

3. Electrically heated tape from Kelly / Thermowing is a relatively new development.  A specially made "heat tape" is added to the leading edge of the wing and coupled with a high power (100 amp, 70 volt) alternator and automatic controller to prevent ice from forming.  The advantage is that the system is relatively easily to add, except perhaps for the additional alternator.  The disadvantage is that the system does not provide any run-back ice protection and is relative new/unproved.
   
    For more information visit Kelly Aerospace at www.airplanedeice.com
    

4. Electro-expulsion is another relatively new technology, where a thin electrically activated panel is added to the leading edge of the wing.  When activated with a high energy electric burst, the panel "snaps/pops" and breaks the ice away.  This system is relatively unproven.
   
   For more information visit Ice management Systems at:  www.icemgmt.com
    

5. Another method of ice protection for props are heated pads attached to the inboard 1/3 of the prop blades (called a hot prop).  Ice does not normally form on the outer sections of the prop due to the high centrifugal forces there.  The inner pads are small enough that abnormally large/special alternators are not normally needed.  These are proven and effective.

Conclusion / Decision:  If the TKS system were available for the ES, that would be my 1st choice.  Since it is not, I've opted for prop protection only, initially, but may choose to add the Kelly / Thermo-Wing tape later.  In case the TKS system becomes available and needs to be fed through the leading edge (from the back where the normal ES electrical conduit is), I added a second/alternate conduit, behind the main spar and added an extra fluid tank in the wing (behind the spar) which could be used for glycol.

I also decide to order the hot prop pads installed on my propeller.  This follows the thinking that (in an inadvertent encounter) some protection is better than none, even if it is only partially effective.

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Brakes:

The standard Lancair ES kit includes Cleveland Brakes which use organic break pads.  This has proven to offer good performance with reasonable longevity and relatively low maintenance.  Lancair offers an upgrade to Cleveland metallic pads, which provide superior performance, but with the potential for shorter longevity and/or more maintenance.  Unfortunately the calipers between the two versions are not the same so switching involves purchasing an entire new caliper assembly.

Conclusion / Decision: I opted for the upgraded metallic brakes

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Build Assistance:

I scheduled for 5 weeks of builder assist due inpart to my desire to extend the fuel, add an aft tank, and move the electrical conduit,

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Avionics:

Undecided.  The top of the line is the Chelton EFIS system.

For more information on Chelton systems visit: www.direct2avionics.com

 

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12 vs 24 Volt Electrical System:

Traditionally (i.e. back in the 70's), aircraft electrical systems were based on a 12 volt system similar to most automobiles.  Overtime, most (all?) certified (production) aircraft have transitioned to 24 volt systems.  An advantage of 24 volt systems is that more power (watts) can be created from a similar sized (weight) alternator.  This is especially beneficial for designs that have a high power draw (i.e. prop deice heater) and/or that incorporate a small 2nd alternator as a backup.  As a 12 volt unit, the backup might only typically be large enough to power the most essential minimal equipment. Whereas a 24 volt backup unit could support nearly all normal flight equipment (which is safer).  An additional benefit of a 24 volt system is that more power (watts) can be transmitted through a smaller wire, which saves weight and space.  This is especially beneficial in designs with the batteries being located in the tail of the airplane and the engine/starter located in the front (necessitating a long large battery cable), and is even more beneficial in a composite plane which also needs a separate large ground cable from the starter to the battery.

The disadvantage of 24 volts systems, is that most (relatively inexpensive) automotive style electrical components are 12 volts, and 24 volt aircraft versions of the same thing are almost always more expensive.  Additionally, some electrical items are only available in 12 volts.  Thus, 24 volt systems normally include a power converter which drives a 12 volt sub-system for the 12 volt equipment (think extra weight and/or another potential failure point).

Conclusion / Decision:  24 Volts.  Despite the cost and 12 volt power converter requirement, a 24 Volt Electrical System is safer and more appropriate for an aircraft like the ES.

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Other Options & Design Considerations:

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Copyright © 2006. All rights reserved. This site is the online project notebook of Rick Titsworth and for the purpose of sharing information and opinions related to building N272RT.  No responsibility for the accuracy or usefulness of the information is expressed or implied.  Any person using these images, ideas, and tips does so at their own discretion and risk and without recourse against anyone related to this site or the n727rt project.  This site is not affiliated with Lancair International.