9

A simplified analysis of column buckling shows that the axial load required for buckling is directly proportional to the second moment of area of the column's cross section: $F=\pi^2EI/(KL)^2`$`, where F is the buckling load, E is the elastic modulus of the material, I is the second moment of area, and KL is an effective column length based on the geometric ...


6

Well, I would solve with transparent Monokote if it was a model. No accounting for people's taste. Although some very early aircraft featured that look, designers soon realized that covered "slab" sides not only reduced drag, but also improved directional stability. Note that covered area aft of CG acts as an extension of the empennage, allowing for a ...


5

Yes, of course you can. However, it's probably not a very good idea. PVC pipes are pretty strong and light; circular-section PVC pipes have an excellent strength-to-weight ratio. Being strong and light isn't enough though. Construction materials need to have the appropriate properties (like being strong and light) in the right conditions. In the case ...


5

I fly part 103, specifically a Hy-Tek Hurricane. I also have a G meter on board. It is a Dynon D2, which features an artificial horizon (attitude indicator) and also a G meter. The average G's on takeoff is pretty small, usually around 1.1 to 1.2 Gs. I can also tell you it is impossible to pull anything over 2 G's during takeoff. I actually performed this ...


4

It's a 100cc engine, and it's in the Radio Control section of that web site. It's an engine for model aircraft. I suppose, technically, that's a home-built aircraft, but you're not going to sit in it!


4

Please read the answer to this question first and try to answer the questions listed there. You need to provide more information! Next, the best place to look is among glider airfoils. The Wortmann FX 63-167 is now 55 years old but still a good start. It was designed for the low speed of a human powered aircraft and has been used on gliders and motor ...


4

I would agree with @TomMcW that joining EAA would probably be a good idea. You could also join the Homebuilt Airplanes Forum. I assume you already know the basics of choosing materials. They are a balance of strength, weight, and cost. I assume your choice of PVC is low cost. So, the big question would be whether it has the rest of the required properties. ...


4

The answer depends on how quickly was this 2 m/s velocity reached. Could be 2 g if it happened within 0,2 s (9,81m/s² + 2m/s / 0,2s) Could be 1.1 g if we were accelerating for 2 seconds to get to 2 m/s (9,81m/s² + 2m/s / 2s) Example accelerometer recordings taken during the Cessna 152 takeoff (not exactly ultralight, but also a small plane). The first ...


3

You can prevent engine vibrations from being transmitted to the airframe by motion cancellation techniques. Similar in principle to Active Noise Reduction headsets that generate an inverse pressure wave to cancel sound, motion cancellation generates an inverse displacement of a mass to cancel vibrations. Sensors determine the vector(s) required, and ...


3

A simple explanation of buckling failure is a kinking of the tube wall. Force on the tube deforms it out of round. A flat side is weaker than a curved side just as a flat piece of paper bends more easily than a paper tube. With enough force the flat side folds. Filling the tube with any material that prevents the initial deformation (keeps the tube round) ...


3

The controls of any aircraft should move easily under the pilot's control. Large aircraft have hydraulic servos to assist the pilot, or even complete fly-by-wire systems, while smaller aircraft often have aerodynamic trim tabs which act as a simple assistance mechanism. On the ground, with no aerodynamic loads, the controls should move easily without such ...


3

Yes, the centre of gravity can coincide with the aerodynamic centre of the main wing, particularly because that point is rather unremarkable. For stability, the centre of gravity needs to be ahead of the neutral point, but that is the overall aerodynamic centre if both main wing and horizontal stabilizer are flying at the same coefficient of lift, which ...


3

For longitudinal stability in a conventional wing-and-tail layout, the CG needs to be ahead of the wing's AC. This causes a nose-down moment that is countered by downward lift at the stabilizer, so that the stabilizer will raise the nose as speed builds up. Thus, if the aircraft is disturbed into a dive, the nose will automatically rise as speed builds; ...


2

Strictly speaking, yes. That is not to say the airframe is dangerously unstable in yaw or prone to spinning, only that the tail boom does contribute slightly to tail volume, so, disregarding any weight and balance effects form the fairing and assuming everything else stays the same, the "naked" version will have less lateral stability. The vertical tail ...


2

First of all, lets start with a short introduction on buckling. There are two types of buckling, global (or column) buckling, and local buckling. Global buckling is what happens to long slender (thin) structures, with a compressive load. Say you take a piece of plastic pipe with a diameter of 3/4 inch (2 cm +/-) and a length of 8 feet (2.5 m +/-). You ...


2

Assuming that the same wing chord is used for both, one technical difference between the Pietenpol and the Riblett is the depth of the airfoil. The Riblett that has been used on the Air Camper is the 612 (or sometimes the 613.5), which makes it 12% (or 13.5%) deep. With a 60" chord, that's a depth of 7 to 8". The deepest section of the stock Pietenpol ...


2

As you've noted, engine mounts are used to isolate the vibration of the engine from the airframe. Another technique is Dynamic Prop Balancing - adding weights or washers to specific places on the propeller or spinner to eliminate the vibrations. It's the same idea as is used to balance car tires.


2

For a non-working prototype it doesn't look too bad - you have a bell crank connected to a control arm that's attached to the aileron. However, the devil is in the details and messing up a detail can kill you. You will want to use acceptable materials and construction techniques (See AC 43.13). You need to ensure the bell crank is the right size so the ...


1

Scale up to the DA-150L, https://www.desertaircraft.com/products/da150l. It's more mature and widely available. With a 32x12" prop it gives 82 pounds of thrust at 5400 RPM. It puts out 16 hp. The "original ultralight" Easy Riser flew with just 11 hp. So it's possible. Here's some broader discussion of more than just the powerplant: Can an ultralight ...


1

You can use any engine in a homebuilt or ultralight, including one from a Model A Ford if you want. A 10 hp RC engine that runs at 8000 rpm? Even if you were building a single seat ultralight, in most cases you'd need at least 3 to 4 of them to have any kind of decent performance, if you could stand the racket they make. For something that can carry two ...


1

Perhaps the choice of the engine helps, flat-six does vibrate less than in-line engines, also Wankel Rotary Combustion Engines have an intrinsic very low level of vibrations. Some interesting approaches were proposed, as this patent from the extinct Barcelona Based motorcycle maker: 'Sanglas'. They once prepared a working prototype for a single-cylinder, 4-...


1

Not sure what specific feedback you are looking for here, but if the question is "will this work?" or "is this a good idea?" Then the answer is probably not. If you never built a plane before and have never even seen the design before, just making it up as you go is not a good idea. If this is a toy remote control plane, then you could get away with it. But ...


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