Sailplane speed limit?

As an aircraft engineer I have deep concerns over composite and plastics used in aircraft construction. I personally don't think they can possibly last simply because repairing structural damage cannot be 100% guaranteed. Metal and wooden structures are easily repaired or replaced. Splicing and repairing plastic and composites are not so easy and expensive to do. It's often cheaper to buy a new one, which means that the aircraft will be written off rather than anyone having to guarantee any complicated repair. Metal aircraft, however, can easily be repaired given a skilled sheet metal worker and the repairs are often stronger than the original structure.
What worries me about plastic is its tendency to become brittle over time. Most of us have experienced those horrific plastic garden chairs that don't last more than a year before they break. Whilst composite aircraft are clearly of superior quality, I like to see a manufacturer who is prepared to guarantee that his composite (plastic) aircraft will not suffer the same fate over time. There was a plastic glider that broke up in the UK in the late 70s. The owner had painted a dark green band around the rear fuselage just in front of the tail. The differential heat absorption from the sun seriously weakened the area and the tail broke off in flight. No-one can tell yet what we will be confronted with in the future or what people might do to their aircraft and I predict that many will have to be retired when we find out the real lifespan when they start to fail. I personally would need a lot of convincing before I bought one.

I can speak confidently but not authoritatively on this, so let's consider this answer tentative. I would be glad to be corrected.

Military gliders were replaced by helicopters after World War II, and no one seems to have found a civilian use for large ones. Unpowered flight is a sport, now, so there don't seem to be any with more than 2 seats. The only recent exception I can think of is the Space Shuttle, which was unpowered during its return from orbit.

Older planes are usually very good purchases, IF they have been well maintained over the years. Airplanes have to be inspected annually by an A&P mechanic with an Inspection Authorization so they are usually very well maintained. Any purchase should include having an A&P mechanic review the airframe and engine logs and evaluation of the plane, including looking at how many hours the engine has since overhaul and checking compression. I had a 1966 Cherokee 140 for several years and finally sold it when I bought my current Experimental aircraft (a BD-4). It helps a LOT if you can get an A&P license and maintain you own plane though.

I recently browsed a forum where this was debated by the FE believers vs normal OE people. (Obloid Earth).
The FE'ers simply believe that photos, videos etc are hoaxes. :))

There are some speed limits for certain types of airspace. Airliners are always in contact with air traffic control and in order to keep the required separation of aircraft sometimes the controllers will ask the pilot to maintain an airspeed. More than likely you experienced a slowdown while your plane was beginning an approach, During approach controllers have to maintain specific spacing between aircraft and often must slow them down behind slower aircraft. Your plane very likely was slowing down from approx 570 knots to 250 knots or less for the approach.

Usually it is airspeed of the aircraft. Each aircraft has different airspeed requirements for operation the flaps or landing gear. Usually that speed is determined by the airframe manufacturers and the design of the flap system component. You could built it strong enough to handle any airspeed, but a plane can only carry so much weight. If you built everything to work without any limitations you might have an airplane too heavy to fly. Designing a plane is a balance between lifting capability and weight. Both of these are important design parameters.

Departure controllers have blocks of airspace with altitude limits. Chances are that there was other traffic that they needed to have out of the way so they held him at 5000 before clearing him to the next controller's airspace.

James,

There are navigation and softwares inside the cockpit so pilot can find easily as well as air traffic controllers will guide them so they can easily land there....
with regards,
jaijith

You will just have to get checked out on any aircraft that you want to fly, with a flight instructor.