PB666

If you run a piston engine to FL500, viability, is no longer a fathomable quality. IAS of a craft at FL500 is 43.3% of ground speed. If the Ne of the engine is say 400Mph, the highest IAS it could fly at 150 kts at 50,000 Po = 101,325 kg/square meters. at FL500 its 19,000 kg/square meter. You have to be checked out on every plane you fly, but if the plane is dramatically different from your experience level, it might be hard to insure. THis discussion has gone into never-never land.

True or not True. Dream Chaser will have a payload fairing. Centuar 2nd stage with an P&W RL10A engine Atlas V with with 2 boosters The boosters will be AJ60A. The core will have __ RD 180 engines. See nothing about Orion

So if the vehicle is unhealthy do they like call in a rocket doctor. Does he like stick a greasy latex covered Ford probe up a rocket engines and twist? What kind of medication would you prescribe to an unhealthy rocket. Anti-depressants, appetite stimulant, or a shin splint? Wouldn't save them alot of money to do the testing of the first stages at the assembly plant or recycling plant, then wrap the rocket in nice cushy reusable foam and ship it to the launch pad. Wouldn't save them on the Pad test to have a dumb mass, something the same shape and mass that could be filled with water an then drained. Seems awful expensive to do live fire tests on a full load of fuel when all you really need to do is fire for a few seconds just to make sure the engine got there safe.

He's the engine of death. As would be the case if humans went to a planet with all purple archean.

What does that mean?

Why would they make more if they haven't tested the first .. . . .they also would be wasting space otherwise devoted to F9 block 5 which is going to be 2018 genre.

Must be one of the plugins that firefox does not support.

Doesn't play

If you are in a pitch black room you will still see something, but then again nothing is there to see.

Yeah I had bought 5 disk drives at once, it think they were Fujitsu and installed them in different computers, it was something like 4 years later most of the stopped working within a couple of months.

Blame in on Elon

https://en.wikipedia.org/wiki/Pratt_%26_Whitney_R-1830_Twin_Wasp Isn't anyone going to ask what engine my Avatar is modeled after?

https://spaceflightnow.com/2017/12/29/rocket-and-satellite-preps-on-track-for-next-atlas-5-launch/ I wonder if this is going to be the ride, good deal of dressing up the mechanics on this, wonder why.

To be quite honest if you are developing an NTR, NASA is a no-go to begin with, or at least not near future in its deployment. So you might want to build the rocket for a despotic demagogue somewhere who wants to do his wild thing on Mars. The second thing is that the Uranium on NTRs is completely safe until fired, and if you are using this as a deep stage engine you are only going to want to fire it when you are well clear of Earth. Its better to have your late circularization engines to give you a apogee somewhere beyond GSO where you can fire it and no-one will really figure it out until months later. Although I must say USAF tracks every new object in space, particularly from despotic leadership countries.

My vision isn't that good, neither is the image.

Are you sure its a piston, it maybe motor driven, or pull wires on the inside.

If you are building for personal use, probably, if you are building for commercial use. . . . even the best designed planes require lots of certification. Just remember in the commercial aircraft business its NOT just being able to fly. Here are some of the qualifications 1. To fly in airspace to commercial airtraffice 2. To land at IFR approach only airports or runways in those airports 3. ETOPs. . . . . . We haven't even gotten to passenger ready certifications. IF you look on the left hand side of every Boeing cockpit instrument panel you will find something like B723-021 and some more numbers. Those numbers the FAA tracks from the time the AC is built until it leaves service in US airspace, so if you forget to do anything or are neglectful in your care, and something happens, a passenger fails and breaks their ankle, whatever, they are going to go looking for a cause. You can build an airplane from a kit (I wouldn't unless I was a certified mechanic), and with a minimal pilots license you can get it certified to fly, and as long as you stay out of restricted airspace (pretty much everything above a certain altitude and and around paved airports) you can take off from small asphault and dirt runways . . dirt country roads . . . . .VFR navigation (poor man's IFR . . . .i fly roads). They really don't care about you unless you crash near a populated area or enter restricted airspace. Again I can see the need for single engine craft . . . .manueverability (crop dusters, bush pilots), light weight (landing in unimproved landing areas, landing on water). low takeoff speed (taking off from short runways) . . . . . BUt for everything else twin engine is the way to go . . . .single engine craft are not unsafe, there is just so little margin for error in the low end market. These bush pilots are experienced pilots, even the best of these have fatal accidents through no fault of their own, the only difference is there is a good need for their skills. You can say the same thing about a DC-3, its insane for people to still be flying aircraft that are approaching a century in age . . . .but for the fact they are sometimes the best at what they can do.

Yes it does, its goal was to create a creature that build fictitious rockets and launched from fictitious planets. Whoops, I guess it doesn't have a goal anymore. Time to reboot. Flying (gliding) snakes are bilaterally asymmetric in glide. This is sort of a faux analogy, because things that don't fly are mostly symmetric to begin with. Thus they are retaining what they have. When we talking about the evolution of animals, particularly predators there was selection to move the femur from the side of the hip to under the hip and basically compress the trunk of the creature in horizontally along the midline of the body. A cheetah is an example of this in the extreme. I just want to make the point that in an emergency you don't care how the plane is pulling when in flight because you can fix that in your approach, anyway. You would care much more about not having lift than not being true on the Yaw. Once you call an emergency in flight, center will clear space around you (hopefully) so all the pilot has to do is find a vector that crosses the glide slope of a runway and turn slightly before he intercepts, if he comes in at a higher approach angle he can kill the thrust on the second engine and glide into land. Secondarily, if your asymmetrically powered craft is pulling a bit in one direction because of differential drag or thrust . . . . . Just throttle down one engine a bit . . . . .if it tilting a bit just move one elevator a bit. If its yawing move the horizontal stabilizer a bit. If you think this is a problem, a commercial Aircraft traveling above 15,000 feet can experience winds aloft at 120 m/s, if these winds are 135 and you are traveling 225 at 200 m/s . . . . . . . . . this is flying. Its why radionavigation was created. There are on most aircraft 7 control surfaces that can be adjusted 9 on the larger ones, that's not including the engines on multiengine craft that can be deferentially throttled. So why do we have symmetrical aircraft? You are on an inbound on the first of 2 stops between JFK and Denver at Cleveland then Chicago then Denver. Upon departure weather conditions in Cleveland have deteriorated and ice is now potentially forming on the runway. There is a slight crosswind and heavy gusts. The controllers in the tower are considering closing the airport to deice the runway, you have already been given clearance to land, at which point you find that your thrust diverters are not working and as you apply more pressure on the breaks the aircraft begins to turn and you are off the runway and your wingtip has just anchored itself in the mud as you spin even more feverishly. Airlines are not particularly amused with runway acrobatics, particularly when it involves the words "loss" and "airframe" when used in the same sentence. Secondarily, in the modern age airlines that profit love consistency, look at Southwest and its devotion to the 737, you don't want odd aircraft in your livery. You want a plane that can be used on any route, land at any airport, have ground crew that are fully experienced to repair . . . . . Ford produced a three engine commercial airliner, as with DC10 and DC11 and Boeing 727 (which was one of the fastest not-wide body commercial airline ever produced). But think about it the craft are symmetrical but they have two types of engines. On a twin with two slightly larger engines they only have one type to deal with. Compare the Ford triplane with either the DC3 or DC4 (both still in active use). Look at those engines for the DC3 . . . . designed to survive . . . Every airline knows that sometime in a jets life they will have to replace the engines, some of the earliest 727s have had two engine replacements, you want this process to be as trouble-free as possible. If you want asymmetry, hire Picasso for a skin job.

I was just admiring their struts. errrr guy-wires PS. whoever submitted this image . . . . nice.

Well here it is if anyone wants it, its a flow chart from hell but. . . . All you are given in this example are std gravitational parameter for an object, <P> and <V>., ">" means they are 3-D vectors. These are in R3 space. I will say with all the math it might be better to change coordinate systems and switch back when finished. The first thing that we know we have is a normal to <P> and <V> is <T> the tangent to both (we assume that no rocket can fly absolutely strait up or down. <P> x <V> = <T> [Note that when crossing vectors that crosses in the same direction are 0 so the Px * Vx = 0 x . . in the R3 universe we use right hand rule. P goes in as 1's, V goes in as 2' and T comes out as S Public Sub DefineTangent(X1 As Double, Y1 As Double, Z1 As Double, X2 As Double, Y2 As Double, Z2 As Double, S1 As Double, S2 As Double, S3 As Double) S1 = Y1 * Z2 - Z1 * Y2: S2 = Z1 * X2 - X1 * Z2: S3 = X1 * Y2 - Y1 * X2 End Sub (1) Once we know the normal we have the Equations for all points in the plane of the elliptical Tx * X + Ty * Y + Tz * Z = 0. In this way we have cut the size of the universe to ∞2/3 We can define any point ellipse by its Θ as r = l / (1 + e cos Θ). We have to realize that extraction of pXY does not suffice. Even though we know an elliptical in R3 space it is an ovoid manifold where each r is a circle about the semi-major axis only one of these planes with its velocity vectors fits the above equity 1 and only one plane has coordinates that are in the XY plane, and unless the orbit is equitorial, they are unlikely the same. As inferred above calculate l and e which immediately fall out of equations already listed above. One could use a squeeze between a recursive computational regime to get a set of coordinates whereby ||query|| = r. The equation for any point of an ellipse from its center is given by r = (a cos Φ)2 + (b sin Φ)2 https://www.mathopenref.com/coordparamellipse.html [quoted because X and Y are not in our coordinate system but in the elliptical] however we are starting from F1 and are only given a measure of distance from the center. x = h + a  cosΘ y = k + b  sinΘ  So lets review what I have F1 is on (0, 0, 0) and C is some point on the R3 that is -ea distance from 0, 0, 0 such that X2 + Y2 + Z2, <T> is tangential and is pi raidans from the periapsis. From C the position can be mapped in the elliptical. Im not going to worry about the position of the Pe for now, it will pop out later. I am just going to assume that i have. In an ellipse the X axis is defined as the semi-major axis. the F1 and C points anglular begins on the ellipse are along the X-axis with the point a that crosses the elliptical closest to F1 therefore F1 and Pe lie Θ0 direction from C and Apo. C and Apo lie Θπ from F1 and Pe. Next the angle we are give to jump to is given as a Θ, lets call it Θj (See above). We want to calculate the coordinates of this angle, the problem is that Θj will only give coordinates in the X,Y coordinate system. and to get them in x,y,z we need to use the center based program and the Angle defined by J C and F1. To do that we need the unit vectors for a [_Au below] (we already have these to get C, and if we didn't all you would have to do is normalize them), for b the is the normalize vectors of <a> x <t> crossproduct (defined above just plug the variables in _Bu). Φ is the C centered angle of J (defined above). Jx = Cx + a cosΦj xAu + b sinΦj xBu Jy = Cy + a cosΦj yAu + b sinΦj yBu Jz = Cz + a cosΦj zAu + b sinΦj zBu Finally after much work there is one half the solution. We need a velocity vector, we already have the magnitude, SME = V2/2 - PE and we know SME and PE (µ/r) so that we know V. We also know V has a negative radial velocity because it is traveling from Apo to Pe (this we have just left P or Apo and jumping to a burn point. So the magnitude of the tangential velocity to <j> is 2 * Sweep/ (r * vtan). Again this is pependicular to normalized crossproduct <J> X <T>. The remainder is the -SQRT(V2- Vtan) as Vrad and . <Vrad> = Vrad * <Ju> <--- unit vectors of J. Sum <Vtan> + <Vrad> and now <L> is known. So the last missing part of this are the Keplerian parameters that will be needed above. a = -µ / (2 * SME) Period = (2 * Pi * a ^ 1.5) / µ^2 Normalize X, Y, Z, r, Xu, Yu, Zu <===== unit vector definition vRad = DotProduct(Xu, Yu, Zu, vX, vY, vZ) <===== This is the Pu*V vTan = SQRT(v^2 - vRad^2) <====tangential velocity omega = vTan / r <==== angular velocity Sweep = (omega * r ^ 2) / 2 Area = Sweep * Period b = Area / (Pi * a) l = b ^ 2 / a e = (1 - b ^ 2 / a ^ 2) ^ 0.5 Pe = a * (1 - e): Apo = a * (1 + e) So with these defined the only thing that really remains is determining is the position of the center. We actually know sort of where the Pe is based we can figure this out also. This is rather a hard part, knowing how far Pe is from the Origin and From P. and from this we know where P is from the line F1P. This creates a circle that crosses the elliptical plane once. So that we only accept the two points that cross the elliptical. The line PF1 and that once passed its -Pu (negative of Ps unit vectors) * r where r = l / (1 + e Cos (Θ - pi)) There is also a perpendicular to <P> at 0,0,0 that is r= 1/ (1 + e Cos (Θ - Pi/2)) and so given the two closest angles to 0 it is possible to estimate since Θ is between two angles which are 90 degrees. At least we know that Z between these is not hilariously different, such as on the North and South Pole of the geodesic, and in general Z should be in a linear range. But since we can use scalars to project vectors we can project both the reversed and perpendicular and because one knows the angle one can extend them so that the line between the two is tangential to Pe and that line is being strait the Position of Pe can be predicted. So that the unit vectors of Pe, we can call Au since the are also the unit vectors of A (Needed above). Then the unit -e * a * Au = <C> thats everything that is required. Its done we jump. Note: about one thing, for P that are low Θ, ||P|| is less than L, P and the perpendicular to P at 0 can be used to perform the trig above instead of (K) The only catch here is when ||P|| = l, the <M> is Pe. For P very close to l the Z component of M can be used to estimate its contribution, then its fairly strait forward to guess PXY bases upon P lambda to the global coordinate system. The calculations will cause significant deviation if performed frequently, however during one cycle the max this is performed once to jump near Apo and consituitively jump to the burn initiation point. Looking at the figure above the spacecraft begins its burn at J and ends at P, then jumps to close to Apo, at very high ISP burns it _can_ correct Pe and then Jump to J. To precent the computer from slowing down the computer has a preset period of time that it test to see if it reaches P, it can easily do this by determining the normalized X,Y, and Z coordinates of the Jump initiation point (where P presumably is when it Jumps to J) When the normal vectors of the ship pass those points (generally going to be arccos Xu unless polar orbit) the ship will go into the above routined and warp to the next burn point.

SSME is pretty decent considering the bleed off for two the turbopumps system. Nuclear thermal rockets ISP in my opinion are poor considering the potential of fission. NTRs IMO are barely worth the effort, I guess thats why NASA talking about building a cryogenic fuel station in EM orbit. And to be frank all you really need an RL10B-2 for if you have decent solar is to push it out of Earths orbit quickly and switch on some new age solar panels and ION drive. They have a decent space engine RL10b-2, and once it is in space it performs well, it produces 4600 Ve and it weight 277 kg, The hydrogen issue is the same with NTR as with R10LB-2 so How much ISP are you willing to trade for 2T of rocket motor. Not only that but RL10b-2 is in production and is actively being used.

Ooooh a wagging finger. I have to say that the government of Antartica is definitely not producing as many rocket flights per year as Iceland.

NERVA is not in the same thrust class of engine as SSME. The SSME is a two stage active turbocharged (as apposed to passive expansion cycle engines) cryogenic engine. If you dumped that much fuel on the Nuclear reactor it would go cold in seconds. If you had a reactor that had enough fuel to heat it it would go prompt critical in seconds. If you want to compare NERVA to something use the RL10b-2.

It really depends on the load, if your close the end of the flight and your load is light, you can go down to the 2000 ft limit and increase performance markedy (unless you happen to live in Denver, in which case find a herd of buffalo and straif them. If you lose an engine on a two engine craft on takeoff at full load, of course you better hope it happens before V1 But again the Concorde had four engines which went to 3 then 2 so . . . . . My favorite piston prop is the DC7, I don't have a favorite jet. But the 747 can easily make home on 3 engines and I think the 777 has about 1000 miles on ETOPs so . . . . . . . I would fly in a twin prop over a single prop anyday, that is to say that I will never fly in a single prop. They should probably be banned except the very low end stuff. I should also point out that a fair amount of crashes in dual props occur because the pilot left his fuel at that departure airport. There's no fixing stupid. We also need to have some perspective here, because some of you kiddies don't know your history. The DC3 was first produced in 1935 as a twin engine tail-dragger. The seems to be pejorative except for the fact that after cancellation of production in 1942 . . . . . . 76 years ago (ahem when you have 76 years you can talk trash) there are 2000 DC3s still in active service. If you need something that the DC-3 does you don't complain about the little tiny wheel on the back. Some of these little, literally, flying antiques in their day were ferrying their loads to common everyday places like the South Pole during ever so slightly abnormal Southern Winter. The advantage it has over turbo props (which DC3 can be retroed with) is that the petro that DC3 can use does not freeze at as high a temperature as jet fuel. Here one of the power plants for the DC-3 The name plate is Pratt& Witney but Wright also dabbled in DC-3 engines Courtesy of Wikipedia.

you would