 Welcome to lesson two in your quest to become a PPC Endorsed Sport Pilot. This lesson focuses on getting the frame to balance properly as it hangs beneath the wing. In the doctored picture to the left, one aircraft is nose high, and the other is nose low, both of which are balance, or center of gravity, problems. The thrust lines will be off, and landing your craft safely will be a real challenge! Once again, while there are few questions on this topic on the test, the subject is critical to know and understand. While we highly recommend that you do NOT adjust the balance point without help from someone who has experience with this adjustment, the knowledge you gain will give you the information you need to ASK for help. Our intention in this lesson is to give you an overview, not step by step directions. As we we will often recommend, consult your Pilot Operations Handbook for more information. Before we turn to Mike Lersbak for this sessions Master Lesson, let’s talk a bit about the first sentence of this lesson where it says “PPC Endorsed Sport Pilot”. We will discuss requirements for your Sport Pilot License in a later lesson, but for now just know that you will be working toward a Sport Pilot License with an Endorsement that will most likely allow you to fly a square winged PPC on the land. Once you have that. you can get further endorsements for square wing water, elliptical wing land, or even fixed wing tricycle gear land or gyrocopter tractor! You don’t get a new Sport Pilot License for each kind of craft, rather, you get endorsements. For more details on this check out this FAA document.
 Birdwalk
For this lessons “birdwalk”, let’s briefly talk about Ultralights, Light Sport Aircraft, and ELSA and SLSA aircraft.
What’s the difference between a Light Sport Aircraft and an Ultralight? An ultralight is a single seat vehicle that weighs less than 254 lbs, carries no more than 5 gallons of fuel, in addition to a few other requirements of Part 103. If you want to fly an Ultralight you can do so without any instruction, test, or license. Within certain guidelines, the freedom, and the risk, is all yours. A Light Sport Aircraft requires a pilot certificate to fly (Student Pilot, Sport Pilot, or General Aviation Pilot), can have a take off weight of up to 1320 lbs, can carry all the fuel you’d like, and can take one passenger.
 Within the Sport Pilot Aircraft category there are two broad types, ELSAor SLSA. ELSA stands for Experimental Light Sport Aircraft. E-LSAs are often virtually identical to an S-LSA but are most often built by the owner/operator. They may not used for instruction or hire (after Jan 31, 2010), and may be maintained by the owner/operator. ELSAs can also include grandfathered fat ultralights,meaning an ultralight that is heavier than 254 pounds, or carries 2 people or carries more than 5 gallons of gas. Our advice is to NEVER buy a fat PPC that is not N-Numbered as an ELSA. The grandfather period is over, so if the previous owner missed the deadline thefat ultralight is now illegal. You’ll see craft like this for amazingly low prices, but don’t be tempted. On the other hand, there IS a way, but there will be restrictions, which will impact resale.
The Special Light Sport Aircraft (SLSA) is an aircraft built to ASTM specifications by the manufacturer and is delivered tested and ready to fly. SLSAs will soon be required for instruction and in rental fleets. Only a certified aircraft mechanic is allowed to maintain these craft.
Other than cost, the difference is partly paperwork, but that paperwork difference will be felt at the time of purchase AND at the time of resale. SLSAs will be more expensive to purchase and maintain, but may hold their value better, as the potential buyer has more certainty that the aircraft is safe for flight, and since the SLSA category is so new, the number of used SLSA craft is very small. We will talk more about maintenance and annuals, and the ramifications of the choice of ELSA and SLSA, in another lesson.
And finally, remember our last lesson on frames? Which of the two aircraft pictured above would you rather be in during a roll over?
Center of Gravity
On your flight test or ground test you WILL be asked about the CENTER OF GRAVITY of your PPC. It’s in the FAA test standards…
J. TASK: PERFORMANCE AND LIMITATIONS (PPCL and PPCS)
REFERENCES: FAA-H-8083-1, FAA-H-8032-29.
Objective. To determine the applicant:
1. Exhibits knowledge of the elements related to performance and limitations by explaining the effects of temperature, altitude, humidity, and wind.
2. Determines if weight and center of gravity is within limits. (SportPilotU.com Hint, check the Pilot Operating Handbook of the craft you are flying for the specifications and limits!)
3. Describes the effects of atmospheric conditions on the PPC’s performance and limitations.
4. Explains the effects and hazards of high winds, referencing the ground speed, high rates of turn, and power requirements
As you watch Mike in this lesson’s Master Video you’ll want to listen for the answer to these questions….
Questions:
The center of gravity tube is
A) lengthened for heavier pilots.
B) shortened for lighter pilots. C) lenghtened for lighter pilots.
Master Lesson Video
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1. Center of balance - Just like a teeter totter. You want balance! In this case the balance point is called the center of gravity.
2. Video #1
- Pilot is positioned forward with cushions. Note where nose of aircraft is in relation to ground.
- Cushions are removed. As weight moves back, the nose goes up.
- The moment arm is affected by how far the weight is placed from the center of gravity(COG).
3. Video #2- The effect of adding weight.
- How much weight would it take to bring the aircraft to acceptable level for this pilot.
- 28 pounds gives us 8 inches nose up, a desirable distance,though you must consult manufaturers recommendations.
- Once again, if the weight is removed, the nose rises.
- The further foward the weight is, or the heavier the pilot is, the more the nose of the craft will go down.
- Set up the aircraft with, typically, 7 to 8 inches of nose high attitude. Consult with Operating Handbook.
#4 - How to adjust center of gravity.
- Fixed wing attachment point
- More common on older craft.
- But center of gravity tube can telescope to adjust balance.
- This has same effect as moving pilot weight.
- This is set for weight of pilot in front seat. Back seat is usually at COG.
- Consult Pilot operating handbook(POH), which gives specifications and limits.
- If pilot is heavier,make tube shorter.
- A fixed bracket, with multiple holes allowing you to move wing attachment point.
- Instead of adjusting where pilot is sitting, as on COG tube, you adjust the COG balance point.
- Be sure you know what you are doing before you do any adjustments.
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