maxtorc Posted February 14, 2005 Author Report Share Posted February 14, 2005 Thanks for your input CAP, was looking for just that, anything I have not heard before or simply things I have forgotten. Was recently in a discussion about point of no return and it led us to suns true bearing and onto the use of astro compass. I found it amazing how much you forget when you don't use it. I have a database of tips and rule of thumb, but I just wanted to send this out and see what I was missing, as it has been a while since I have used some, (GPS how wonderful). So if anyone can help would be appreciated! Quote Link to comment Share on other sites More sharing options...
Winnie Posted February 14, 2005 Report Share Posted February 14, 2005 I was kinda looking for something regarding Critical point and PNR too, anybody have those memorized? Quote Link to comment Share on other sites More sharing options...
cap Posted February 14, 2005 Report Share Posted February 14, 2005 maxtorc -------you bet "you loose it if you don't use it". May I assume that you are also aware that Ottawa doesn't publish "Navigating By The Sun's True Bearing " anymore? If you didn't, then consider you copy of that manuscript as a rarity. Their reason....get this......."with the proliferous use of GPS, the demand for this document had lessened greatly and therefore any further publishing will cease". Winnie------better explain further what you're looking for because I don't think you are looking for the answer I have in mind.......or maybe you are. Quote Link to comment Share on other sites More sharing options...
Winnie Posted February 14, 2005 Report Share Posted February 14, 2005 What I'm looking for are "simple" formulas to calculate Point of No Return (PNR) and point of Equal Time (PET, also kown as Critical point or Radius of action). I need it in a simple format, so that I can punch the numbers into my calculator and come out with a good/correct result. I have a deal for my E-6B, but it is hard to memorize, and they won't let me bring the sleeve in to do the test (written on the sleeve). Cheers Winnie Quote Link to comment Share on other sites More sharing options...
RDM Posted February 14, 2005 Report Share Posted February 14, 2005 PNR........ E X O X H ________ H + O E = Endurance O = Normal GS out H = normal GS home PET..........(or distance to Critical point) D X H _____ O + H D = total distance from dep to des or....Time to CP CP = D (distance to critical point) ______________________ O (full groundspeed out) ....hope it helps, got more if ya want'em. Quote Link to comment Share on other sites More sharing options...
maxtorc Posted February 15, 2005 Author Report Share Posted February 15, 2005 Cap last time I saw that publication was nearly ten years ago, in all places Red Deer. I think they are available online through an American government pulication. Not sure if they are still available as I found them about three years ago. Quote Link to comment Share on other sites More sharing options...
Winnie Posted February 15, 2005 Report Share Posted February 15, 2005 That RDM is EXACTLY what I was looking for. You got more you say? I'm trying to study for my ATPL and IR these days, so anything you think is useful... Cheers Winnie :up: Quote Link to comment Share on other sites More sharing options...
advancing blade Posted February 15, 2005 Report Share Posted February 15, 2005 Just as a slight variation to what RDM wrote You can drop the last H in the PNR depending on wether you want the result in time od distance. The current ATPs also talk of PSR (point of safe return), in which the E for endurance time is reduced by your minimums, so you don't plan to arrive dry tanks. Also for multi eng heli. PNR / PSR OEI problem Fuel flow out + Fuel flow home (OEI) Gnd speed out Gnd speed home (OEI) = X Available fuel X =Distance to PSR/PNR Distance over Gnd speed out = Time to PSR/PNR Rate of descent..... Glide path angle x Gnd speed[/u] 60x60 x 6080 max radar range............ constant (1&8 zeros meters per second) 2 x pulse repition frequncy Obviously I use these every damned day. post if you have any particular needs, got loads of silly formula A B Quote Link to comment Share on other sites More sharing options...
Phil Croucher Posted February 15, 2005 Report Share Posted February 15, 2005 Current ATPs..... don't arrive dry tanks..... Yikes, I was teaching that years ago! The PNR is the same as radius of action, where the edge of the radius is your limit to use the same fuel to get back to base, useful in the Arctic, over water, or in similar hostile territory. If you have to calculate PNR after an engine failure (in real life, not the exam), calculate the Specific Ground Range and add the fuel used per mile out and back together. Then divide the result into the endurance. Don't forget that the CP has nothing to do with fuel, so just because you have one, it doesn't mean you have the range. You can do CP (and PNR) on the whizzwheel by placing the groundspeed home on the inner scale against groundspeed out on the outer scale. Then look for two numbers which, when added together, comprise the distance or Time To Turn, as appropriate. Other essential formulae (yeah, right) include the output of an AC generator: Power factor = KW ÷ KVA Or the one for calculating VHF line of sight range: NM = 1.25 X <sq root>Height AGL (height is both antennae) Time to station: Time (mins) = Mins x 60 ÷ Degrees Distance: Time (mins) = Mins x GS ÷ Degrees ADF bearing to station: MH + RB = BTS DMA Slant rage: Range = Time (ms) ÷ 12.4 and Doppler shift: fD = fT x V ÷ C where V is aircraft speed in metres/second. Oh yeah, the most useful, density altitude: DA = PA ± (120 x ISA Dev) Phil Quote Link to comment Share on other sites More sharing options...
treetopflyer Posted February 16, 2005 Report Share Posted February 16, 2005 Hey guys, Here is one that I actually use if fuel is becoming a concern. Fuel burn in lbs/NM = Fuel Flow in lbs/hr divided by Groundspeed in NM/hr Try it at a few different torque settings and use the one with the least fuel burn per nautical mile. Also range is improved by increasing cruise speed into wind and decreasing it downwind. Later, ttf Quote Link to comment Share on other sites More sharing options...
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