Asphalt Repair And Remarking: Fill & Download for Free

Great question, because it often goes overlooked, along with the many other components, teams and systems that must work properly in order to deliver humans or equipment to space.We’ll go through what the parts are, how they interact, and then into the actual effects, damage and repairs.Imagine, if you would, a very slow motion solid rocket booster igniting and launching into the air. The ground underneath the pad (or at the bottom) would have to be angled, so that the flames don’t “bounce” back up, and cause additional heat or vibrations to that very rocket. Notice how right away, we introduced a couple new dangers to any healthy rocket plume:We already had FLAME / FIRE / PLUME (PRESSURE!)And because of it, we must add the following two as main dangers during a rocket launch:HEAT / TEMPERATURE(To give you an idea, I’ve posted a photo of thermite. The hottest man-made substance, reaches almost 4000 °F (2200 °C), and burns through asphalt and most everything else… The Shuttle’s SRBs burned at the same or a bit hotter temperatures… more on this below)VIBRATION / SOUNDSo as we said, the first thing we need to do is deflect that mean hot flaming machine at an angle.Enter the Launch Pad TrenchThe pad’s trench was designed not only to be a stable launch platform for rockets (from Apollo to the Shuttle and on), but in being so it contains components that help maintain and improve that stability.The MFD (Main Flame Deflector): This is a ramp-like structure, at two different angles. One to deflect the Orbiter’s three SSME’s (Space Shuttle Main Engines), and the other side for the SRBs (Solid Rocket Boosters). These angles are based on studies, calculations, and the meat and potatoes of engineering, in order to help with the three dangers we’ve identified above.Here is an Apollo Era MFD:As mentioned above, the MFD photos shown from this point on will be for the Space Shuttle program, which will show one side of the Flame Face differently shaped/angled than the other.Watch NASA work super-fast at building the Shuttle-era MFD:How does the Trench and MFD look together as a whole in the pad?These are made of multi-layered reflective concrete, thermal tiles, and other materials. Of main concern is not just damage to the Trench for re-usability, but also the potential for FOD (Foreign Object Debris) or “chunks of stuff” flying out and potentially damaging the vehicle at its most critical stage.Now while that solution may help deflect the super-hot flame to the side, it sure does nothing to mitigate the pressure and sound/vibrations during the approximate four seconds that the Shuttle Assembly (commonly known as the stack) will spend in its influence.The study:After NASA failed to convince a lot of people and a few chimpanzees to stand under there with a thermometer during a shuttle launch, modifications to the MFD were made in order to be able to measure this amount of force affecting various areas of the MFD and trench.(this is probably a good time to notice the orbiter’s SSME flame face on the right, vs the much steeper angle of the SRB’s on the left). Shown also are the sensors that detected the amount of force during launch.The results were something like this.Heat rate after one second of launch (SRB’s):In terms of pressure, this is what was recorded after launch:What is 3660 psi (25.2 MPa) in terms of pressure? About 250 bars, or atmospheres. About 7 full-size elephants standing on an area the size of the palm of your hand. Except it would be 7 elephants for each time the palm of a hand fits in that center area pictured above.So 4000–5000 °F (2200–2800 °C) temperatures, 250 bars of pressure… what about vibrations?Another study tells us “Intense acoustic noise and vibration are unavoidable and undesirable by-products generated by the launching of a spacecraft, such as Space Shuttles. The generated noise during firing of rocket engines manifests itself to launch vehicle, sensitive spacecraft and launch pad in the form of airborne acoustics and structure-borne vibration. Therefore, a successful space mission requires thorough consideration of complex sound and vibration interaction of vibro-acoustics effects. The noise and vibration caused by spacecraft rocket engines on launch pads is extremely intense (approximately 180–190 dB) and produces vibration not only of the spacecraft vehicle but also of the launch tower and related support facilities. These vibration levels can be of sufficient magnitude to cause fatigue and eventual failure of some parts. The noise at launch (also during the two-minute liftoff and trans-sonic climb phase through the atmosphere from rocket exhaust and the turbulent boundary layer excitation, separated flows, wake flows and shocks) causes an hostile noise and vibration environment not only for the spacecraft itself but also for the delicate electronics and payload packages aboard. Then, the primary source of structural vibrations and internal loads during launch is due to these acoustic loads.” (Credit Revista chilena de ingeniería).Above we can see the typical vibration time history during a Space Shuttle launch.Above is a diagram describing the main noise and vibration response of pad structures induced by rocket launch.So to help mitigate some of these vibrations, the following is then introduced:The Water Sound Suppression System:Goes something like this (test, without the launch platform).Bubbles have the ability to absorb a remarkable amount of sound. As sound waves propagate through the water and encounter an air bubble, it causes the bubble to compress. The compression converts the sound energy into heat, substantially dampening the noise.NASA makes use of the effect by spraying water molecules into the surrounding air at the Mobile Launcher Platform. Similar to the compression of the bubbles, when water molecules encounter a sound wave, they begin to vibrate, converting the sound energy into heat.The water system protects massive rockets during launch. Seconds before launch, 16 nozzles create a cascade of water which absorbs most of the sound energy. The system is effective enough to reduce the noise by half. It reduces acoustical levels within the orbiter payload bay to about 142 decibels, below the design requirement of 145 decibels.At the time of liftoff, the flow rate at the Launch Pad exceeds 900,000 gallons a minute (3.4 ML/min or 57 kL/s).Repairs of the Trench after an average Shuttle launch:May, 2008. Space Shuttle Discovery lifts off on its way to the International Space Station. On the meantime, there is nothing but damage and debris on the launch pad, Complex 39A.Inspectors show up post launch to check out the trench, based on video and evidence that shows that debris and construction material flew about 1500 ft (500 m), almost reaching the perimeter fence.NASA then wrote “With its protective bricks torn away by the recent space shuttle launch, the flame trench at Launch Pad 39A will be given a new layer of protection in time for the next space shuttle liftoff.The flame trench channels the flames and smoke exhaust of the shuttle's solid rocket boosters away from the launching spacecraft.A swath of about 3,500 protective bricks tore away from the walls of the structure when space shuttle Discovery lifted off May 31 to begin its STS-124 mission. None of the bricks bounced back in the area of the shuttle. Preliminary computer models of the exhaust pattern suggest no likelihood of loose bricks coming back to the mobile launcher platform or the shuttle.Just as a swimming pool is coated with a protective layer before it is soaked, the flame trench will be sprayed with Fondue Fyre, a fire-resistant concrete, to shield it from fire and smoke. Sections of the flame trench already are protected by Fondue Fyre. A shuttle program meeting was held Thursday to solidify many of the details of the repairs.”(Above: Repaired trench, using the Fondue Fyre coating, back in 2009).They continue, “ The bricks protect the reinforced concrete structure of the flame trench from 7 million pounds (31 MN) of thrust generated from the SRBs.NASA’s Perry Becker, who is leading the engineer investigation and repair effort, said it is too early to tell why the wall came apart during liftoff. The wall was built in 1965 and has endured 82 launches, including 12 liftoffs of the Saturn V rocket.Each of the bricks weighs about 19 pounds (8.6 kg) each and the tongue & groove design allows them to interlock with each other for additional support. The force of the shuttle's solid rocket boosters carried some of the bricks approximately 1,500 feet (500 m) from the launch pad. “(credit NASA Spaceflight).In summary, after the Space Shuttle era, the trench in both Complexes 39 A and B have been overhauled to host the next generation of rockets.(The renovation of the Launch Pad Trench)I leave you with this amazing footage of Michel Mephit, walking around the Endeavour Space Shuttle, and making his way down to the trench, able to stand directly below the SRBs.Amazing!All the best,

When I took my yearly trip with my teenage kids this summer, traveling from Michigan’s west coast to Ottawa, Ontario to visit my family, the first thing my son remarked after crossing the border was how nice Ontario highways were as compared to Michigan ones we were just on.I have to agree. At least for highways. City and regional roads can be a different matter.While the amount of mileage for 400-series highways in Ontario is roughly the same as the mileage for Interstates in Michigan, Michigan highways receive a lot more punishment from much more traffic, with less funding to cover repairs. Plus I’m positive that Ontario highways are constructed to much higher quality (and cost) than they do here in Michigan. Plus they’re almost entirely asphalt, which while need to be replaced more often than the concrete used on most Interstates, doesn’t destruct like concrete will, causing that battle scar feel to most Michigan highways with broken and patched concrete. I can only imagine what kind of damage to Michigan vehicles that rework causes.

I happen to be 82 this year and I do all of my own home maintenance. But about two months ago I had to do some repair work on my large back porch the eve 24 feet of it was completely rotted out after 12 years I had built it in 2007 but I didn't get the roof on it until probably 2008 and it did not time. Even with the painting and everything a 2 by 12 fascia board completely rotted at least 70% of it I couldn't believe it so I had to take a look of course of asphalt Roofing off and replace it mainly because I didn't want to reuse the roofing you know I got it all off I had a date to eat the metal drip edging off. When I got that all done and replace the two by 12 which was a job for me at 82 I didn't have any help I was going to use felt 15 pound felt to recover that 3ft that I had to remove but then I looked at this stuff that was like five times more expensive to give you an idea or role of it was 7 / set $80 with tax and you can buy a rule felt for under 20 I decided to go to the expensive stuff I couldn't believe how tough that stuff was and it did a remarkably good job I just slid it underneath what was still on the roof let it hang over a bit put the metal strip back on my reused it all I had to buy a one section because I had to shorten the metal at Each corner in order to get it off properly without severe damage but after I got all that done got the ass Blue Asphalt shingles down it's almost done now but I would buy that new underlay roll stuff in a heartbeat it’s great stuff highly recommended spend the money. A roof is extremely important to your house no matter how you look at it! Do it right and a roll of it will last quite a while. I think there's almost 285 ft material on one roll that's a hell of a lot more than what's on a felt roll so in the long run it may be cheaper.