CRP5 Questions
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Looks like I taught myself the wrong method, would it be worth me learning the wind down method before I get to do the navigation section of my PPL? I passed the nav exam using the wind up method having spent 3 days with the Thom manual, map, CRP-5 and PPL confuser.
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SothernHighFlyer,
I wouldn't bother to change at this stage until your PPL is complete. Pass the Nav Test using the method you understand.
If you decide to progress beyond PPL, change to 'wind down'.
The Drop,
We can't find the quoted reference. We are wondering if we got the information from the CAA through an email or letter. But, as I said, I can assure you that what I said was correct. We issue the Casio fx-85WA to our students, but any inexpensive non-programmable scientific calculator will do.
Paul
[ 15 January 2002: Message edited by: Paul Hickley, Gen Nav Spec, Oxford ]
[ 15 January 2002: Message edited by: Paul Hickley, Gen Nav Spec, Oxford ]</p>
I wouldn't bother to change at this stage until your PPL is complete. Pass the Nav Test using the method you understand.
If you decide to progress beyond PPL, change to 'wind down'.
The Drop,
We can't find the quoted reference. We are wondering if we got the information from the CAA through an email or letter. But, as I said, I can assure you that what I said was correct. We issue the Casio fx-85WA to our students, but any inexpensive non-programmable scientific calculator will do.
Paul
[ 15 January 2002: Message edited by: Paul Hickley, Gen Nav Spec, Oxford ]
[ 15 January 2002: Message edited by: Paul Hickley, Gen Nav Spec, Oxford ]</p>
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Thanks just hope my instructor can cope with the wind up method when we do the navigation bit. Even if I wanted to I very much doubt the CAA would let me do much more, though I do plan to add an IMC rating eventually. If the APTL ground exams were cheaper I would consider doing them as the PPL ones were not enough of a challange.
Moderator
May I follow up on my previous post now that I have had time to play with the two devices.
(a) first I must again 'fess up to the arrogance of my ill-considered first post .. it would have been far better had I done the homework then (before commenting) rather than now .... c'est la vie ...
(b) DesiPilot was quite justified in being a little concerned and, while Paul Hickley and Send Clowns clearly understand the following, it may be of use to other readers to review the salient matters under discussion. It confused me to start with .. and I guess that there will be others in the same boat ...
My comments relate to the conventional Dalton and CR styles of computer in respect of the typical navigation solutions mentioned below. (I loosely refer to "vectors" for convenience .. not quite rigorous .. but convenient shorthand for a "line drawn to a scale speed and plotted at correct azimuth").
Dalton (E6B)
The Dalton provides a means to plot the W/V end of the navigation vector solution (navigation triangle).
The picture we get is the same as if we plotted the triangle directly onto a sheet of graph paper. The easiest way to think of it is to consider the instrument "floating" above the graph paper .. we look through the rose to obtain a view of the grid and the triangle, much in the same way as MS Windows provides a screen through which to look upon the "desktop" beneath.
The conventional solution requires that the centre of the compass rose viewer be located over the intersection of the TAS/HDG and W/V vectors. For this approach, when plotting the W/V vector, it is drawn "wind down" from the centre point.
However, because of the way the grid is drawn (r-theta, azimuth-range, angle-distance .. whatever descriptive term you might prefer) it doesn't matter if one positions the centremark over the other end of the W/V vector .. ie the intersection of the TR/GS and W/V vectors. This is what happens if the W/V vector is drawn "wind up" from the centre point .. actually it makes more sense to think of the W/V in this case as being plotted down from the end point to the centrepoint of the rose as the direction of the wind as plotted is exactly the same.
The instrument plots exactly the same triangle regardless of which approach is adopted. To see this more easily, try drawing an example on paper and then orient the paper with the instrument. To change from one technique to the other is just a matter of moving the instrument "over" the triangle to reposition the centrepoint while, at the same time, rotating it to remain aligned with the radial spokes of the grid.
The solution is read exactly the same for each case .. it doesn't matter which technique is used .. provided no careless mistakes are made, the correct answer results.
The suggestion that the unconventional technique can save a little effort is true, but rather illusory.
It may be helpful to look at the typical navigation problems which we routinely solve on the instrument.
(a) Given W/V, TR, and TAS .. find HDG and GS
The conventional "wind down" plot requires some iteration on the part of the pilot to obtain the solution. The alternative "wind up" technique gives the answer directly. Just be careful of confusing the decal markings.
(b) Given TR/GS and HDG/TAS .. find W/V
Either way works fine.
(c) Given HDG/TAS and W/V .. find TR/GS
The standard way works fine. If you use the "wind up" method, you end up having to do the same sort of iterative processing which the technique sought to avoid in (a).
(d) Given W/V and TR/GS .. find HDG/TAS
Similar to (a).
I really can't see that there is any significant advantage to be had in using the alternative method. If you take the small workload reduction in (a) and (d), you end up with the same sort of problem in (c). A matter of preference, I guess.
. .CR
The CR works a little differently .. to save size .. which offers the advantage of its being able to be carried in one's shirt pocket.
To remove the need for a bulky slide, rather than plotting the standard triangle, a line is drawn through the intersection of the HDG/TAS and W/V vectors and perpendicular to the TR/GS vector (or its extension). This results in a triangle to be plotted which is solved by a combination of figuring simple vector components (left/right crosswind and head/tailwind) and doing some basic trigonometry using the sine and cosine scales around the outside of the instrument (drift and effective TAS) .. the result is no need for a slide with the radial/range grid. It is, however, quite important to remember that we are solving a different triangle from the Dalton, although the end result is the same. A lot of people tend to get confused by this difference.
Unlike the Dalton, there is no need to plot the W/V vector as such and the idea of "wind up" and "wind down" is rather unnecessary. However, the distinction can be made by plotting the reciprocal of the conventional vector .. ie as if the wind is coming from the reciprocal direction but with the same magnitude (speed). Alternatively, this vector can be thought of in the same way as the Dalton situation in that it is just plotted, for curious inconvenience, downstream at a scale distance equal to the wind speed.
The result is that the unconventional plot ("wind down") causes the conventional CR triangle to be rotated 180 degrees about the intersection of the TR/GS and W/V vectors (the rose centre point regardless of which approach is adopted). The pilot must keep this firmly in mind .. while the resolved components of the W/V have the same magnitude the sense or direction, with respect to the instrument markings, is reversed. Provided that the pilot does not make any careless mistakes, the answers are going to end up the same regardless of which technique is adopted.
The standard problems listed above for the Dalton work fine for the CR, regardless of which technique is used. However, with the unconventional method, the mental housekeeping workload on the pilot increases significantly as does the likelihood of careless errors. For the life of me, I can see absolutely no advantage to be had in using the CR instrument in other than the conventional manner. If you want to do so, fine ... just be a little bit careful of the housekeeping workload .. but, surely, it is a bit like marching around the parade ground backwards ? .. a novelty but of little practical value.
. .So, the upshot is that the wind up and wind down approaches, for both computers, can be made to work fine for the typical problems we have to solve. I just can't see much point in using the unconventional technique for either instument, especially in the case of the CR.
. .Hopefully I haven't further confused the issues ....
Amazing, isn't it ? ... near 40 years in the industry and I had never heard of this "wind up"/"wind down" thing before reading this thread ....
(a) first I must again 'fess up to the arrogance of my ill-considered first post .. it would have been far better had I done the homework then (before commenting) rather than now .... c'est la vie ...
(b) DesiPilot was quite justified in being a little concerned and, while Paul Hickley and Send Clowns clearly understand the following, it may be of use to other readers to review the salient matters under discussion. It confused me to start with .. and I guess that there will be others in the same boat ...
My comments relate to the conventional Dalton and CR styles of computer in respect of the typical navigation solutions mentioned below. (I loosely refer to "vectors" for convenience .. not quite rigorous .. but convenient shorthand for a "line drawn to a scale speed and plotted at correct azimuth").
Dalton (E6B)
The Dalton provides a means to plot the W/V end of the navigation vector solution (navigation triangle).
The picture we get is the same as if we plotted the triangle directly onto a sheet of graph paper. The easiest way to think of it is to consider the instrument "floating" above the graph paper .. we look through the rose to obtain a view of the grid and the triangle, much in the same way as MS Windows provides a screen through which to look upon the "desktop" beneath.
The conventional solution requires that the centre of the compass rose viewer be located over the intersection of the TAS/HDG and W/V vectors. For this approach, when plotting the W/V vector, it is drawn "wind down" from the centre point.
However, because of the way the grid is drawn (r-theta, azimuth-range, angle-distance .. whatever descriptive term you might prefer) it doesn't matter if one positions the centremark over the other end of the W/V vector .. ie the intersection of the TR/GS and W/V vectors. This is what happens if the W/V vector is drawn "wind up" from the centre point .. actually it makes more sense to think of the W/V in this case as being plotted down from the end point to the centrepoint of the rose as the direction of the wind as plotted is exactly the same.
The instrument plots exactly the same triangle regardless of which approach is adopted. To see this more easily, try drawing an example on paper and then orient the paper with the instrument. To change from one technique to the other is just a matter of moving the instrument "over" the triangle to reposition the centrepoint while, at the same time, rotating it to remain aligned with the radial spokes of the grid.
The solution is read exactly the same for each case .. it doesn't matter which technique is used .. provided no careless mistakes are made, the correct answer results.
The suggestion that the unconventional technique can save a little effort is true, but rather illusory.
It may be helpful to look at the typical navigation problems which we routinely solve on the instrument.
(a) Given W/V, TR, and TAS .. find HDG and GS
The conventional "wind down" plot requires some iteration on the part of the pilot to obtain the solution. The alternative "wind up" technique gives the answer directly. Just be careful of confusing the decal markings.
(b) Given TR/GS and HDG/TAS .. find W/V
Either way works fine.
(c) Given HDG/TAS and W/V .. find TR/GS
The standard way works fine. If you use the "wind up" method, you end up having to do the same sort of iterative processing which the technique sought to avoid in (a).
(d) Given W/V and TR/GS .. find HDG/TAS
Similar to (a).
I really can't see that there is any significant advantage to be had in using the alternative method. If you take the small workload reduction in (a) and (d), you end up with the same sort of problem in (c). A matter of preference, I guess.
. .CR
The CR works a little differently .. to save size .. which offers the advantage of its being able to be carried in one's shirt pocket.
To remove the need for a bulky slide, rather than plotting the standard triangle, a line is drawn through the intersection of the HDG/TAS and W/V vectors and perpendicular to the TR/GS vector (or its extension). This results in a triangle to be plotted which is solved by a combination of figuring simple vector components (left/right crosswind and head/tailwind) and doing some basic trigonometry using the sine and cosine scales around the outside of the instrument (drift and effective TAS) .. the result is no need for a slide with the radial/range grid. It is, however, quite important to remember that we are solving a different triangle from the Dalton, although the end result is the same. A lot of people tend to get confused by this difference.
Unlike the Dalton, there is no need to plot the W/V vector as such and the idea of "wind up" and "wind down" is rather unnecessary. However, the distinction can be made by plotting the reciprocal of the conventional vector .. ie as if the wind is coming from the reciprocal direction but with the same magnitude (speed). Alternatively, this vector can be thought of in the same way as the Dalton situation in that it is just plotted, for curious inconvenience, downstream at a scale distance equal to the wind speed.
The result is that the unconventional plot ("wind down") causes the conventional CR triangle to be rotated 180 degrees about the intersection of the TR/GS and W/V vectors (the rose centre point regardless of which approach is adopted). The pilot must keep this firmly in mind .. while the resolved components of the W/V have the same magnitude the sense or direction, with respect to the instrument markings, is reversed. Provided that the pilot does not make any careless mistakes, the answers are going to end up the same regardless of which technique is adopted.
The standard problems listed above for the Dalton work fine for the CR, regardless of which technique is used. However, with the unconventional method, the mental housekeeping workload on the pilot increases significantly as does the likelihood of careless errors. For the life of me, I can see absolutely no advantage to be had in using the CR instrument in other than the conventional manner. If you want to do so, fine ... just be a little bit careful of the housekeeping workload .. but, surely, it is a bit like marching around the parade ground backwards ? .. a novelty but of little practical value.
. .So, the upshot is that the wind up and wind down approaches, for both computers, can be made to work fine for the typical problems we have to solve. I just can't see much point in using the unconventional technique for either instument, especially in the case of the CR.
. .Hopefully I haven't further confused the issues ....
Amazing, isn't it ? ... near 40 years in the industry and I had never heard of this "wind up"/"wind down" thing before reading this thread ....
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CRP5 Windarm good/bad
I got the CRP5/W awhile ago and only recently have been try to familarise myself with it. The (W) i.e the wind arm on the windscale initially seemed to get in the way and annoy me and still does abit. When your beginning to learn this I presume it is best to be able to mark in wind point however I am slowly but surely just using the wind arm, not sure if I am using it right though. I was looking in the manual and what i gathered was you use the L end of arm on the H plate and vice versa H end on L plate, however when working on problems the L end on L plate seems to get right ans??? Also To those who use it,once you mastered it was the windarm a godsent or nuisance.
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The Dreaded Windbar ?
The main benefit is speed. Once you've got it clear in your head, it seems to be a quicker method. Saves getting a felt tip pen out and then wiping off the disc. That's about it.
The main disadvantage is that if you get yourself confused, the whole thing goes out the window. I had to practice and practice to get both accuracy and solution right in my mind. Saw someone tear off the bar and revert to the pen 'cause it was causing him a nightmare on one question.
If you're having problems try this, the only advice I can give:
The L side of the arm goes against the wind heading on the H side and you read off the outer arm. You're reading off the high speed arm on the high speed side, just aligning the low speed arm against the wind heading. Vice versa for low speed.
It's easier to show someone than try and explain in text, and I apologise if you are totally confused now !
I did manage to pass G Nav and Flight Planning with a wind bar CRP-5, given the choice I wouldn't bother getting one again.
FM
The main disadvantage is that if you get yourself confused, the whole thing goes out the window. I had to practice and practice to get both accuracy and solution right in my mind. Saw someone tear off the bar and revert to the pen 'cause it was causing him a nightmare on one question.
If you're having problems try this, the only advice I can give:
The L side of the arm goes against the wind heading on the H side and you read off the outer arm. You're reading off the high speed arm on the high speed side, just aligning the low speed arm against the wind heading. Vice versa for low speed.
It's easier to show someone than try and explain in text, and I apologise if you are totally confused now !
I did manage to pass G Nav and Flight Planning with a wind bar CRP-5, given the choice I wouldn't bother getting one again.
FM
Last edited by Father Mulcahy; 20th Sep 2002 at 15:42.
TightYorksherMan
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Crp5 Cdrom
Does anyone own a copy of the Pooleys CRP5 CDrom just wondered what it was like before I decide to invest in it.
cheers
Jinkster
cheers
Jinkster
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i dont have one ... but we have used it in class.
the content seems as you would expect.
unless u really are struggling and have money to burn i would stick with the green instruction book that comes with the crap5, i think that and working rough answers out will get you through.
the content seems as you would expect.
unless u really are struggling and have money to burn i would stick with the green instruction book that comes with the crap5, i think that and working rough answers out will get you through.
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CRP5/Density Altitude Questions
A note of caution to those using the CRP5 for Density Altitude questions in the General Nav exam. After failing the above exam by one mark in the Nov. Exams I was looking at feedback questions with my son. Using the CRP5 for desity altitude problems as suggested , it was impossible to come up with an answer that conclusivly indicated one of the 4 multiple choice answers. The CRP5 just was'nt accurate enough.
My son is registered with BGS and uses their notes and there was no mention of an alternative formula in place of the CRP5.
By chance we were looking through the Pooley's flight nav manual and after getting to the bottom of the section showing how to use the CRP5 for density alt. calculations we were amazed to see underlined in bold type
Until Further Notice Do Not Use The CRP5 For Density Calculations
In the JAR ATPL Examinations. Instead Use the Following Formula:
Density Altitude= Press. Alt. + ( ISA Temp. Dev. x 120 ).
Ater trying the formula on a few feedback questions glad to report that it worked a treat and indicated the correct answer clearly. Hope this note will help a few maybe get those vital few marks. Good luck.
My son is registered with BGS and uses their notes and there was no mention of an alternative formula in place of the CRP5.
By chance we were looking through the Pooley's flight nav manual and after getting to the bottom of the section showing how to use the CRP5 for density alt. calculations we were amazed to see underlined in bold type
Until Further Notice Do Not Use The CRP5 For Density Calculations
In the JAR ATPL Examinations. Instead Use the Following Formula:
Density Altitude= Press. Alt. + ( ISA Temp. Dev. x 120 ).
Ater trying the formula on a few feedback questions glad to report that it worked a treat and indicated the correct answer clearly. Hope this note will help a few maybe get those vital few marks. Good luck.
Jet Blast Rat
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Sorry to hear someone might have failed on this point that is, in my opinion, a very silly, trivial JAA point.
I am surprised it is not in the BGS notes, which are generally very good, but your son should have been told in the groundschool segment never to use the CRP-5 for density-altitude calculations, unless it was a rushed last-minute guess narrowed down to a couple of answers. This is official advice from the CAA (and from me to any of my Nav students who read this, and I told the same thing to last week! My notes are very clear on this, and I don't think they even go into depth of how to use the CRP-5 for this, although the formula comes in that chapter). The answers are not precise enough from the CRP-5, and as far as I can see a different approximation is used by whoever set the scales, because some answers are quite different.
The correct way to answer these questions is, as you say, by using the formula (in the form others may find more familiar)
Density Altitude = Pressure Altitude + 120 × T
or the more accurate DA = PA + 118.8 T (our instrument lecturer teaches this, I don't know if the extra precision is required there. For Nav either is fine)
where T is temperature deviation from ISA, i.e.
T = OAT - (ISA temperature for that Pressure Altitude)
I am surprised it is not in the BGS notes, which are generally very good, but your son should have been told in the groundschool segment never to use the CRP-5 for density-altitude calculations, unless it was a rushed last-minute guess narrowed down to a couple of answers. This is official advice from the CAA (and from me to any of my Nav students who read this, and I told the same thing to last week! My notes are very clear on this, and I don't think they even go into depth of how to use the CRP-5 for this, although the formula comes in that chapter). The answers are not precise enough from the CRP-5, and as far as I can see a different approximation is used by whoever set the scales, because some answers are quite different.
The correct way to answer these questions is, as you say, by using the formula (in the form others may find more familiar)
Density Altitude = Pressure Altitude + 120 × T
or the more accurate DA = PA + 118.8 T (our instrument lecturer teaches this, I don't know if the extra precision is required there. For Nav either is fine)
where T is temperature deviation from ISA, i.e.
T = OAT - (ISA temperature for that Pressure Altitude)
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CRP5/E6B - Any Excel gods out there?
I don't suppose there are any excel gods out there that have managed to duplicate the wind side of the CRP5/E6B and cracked the formulas for doing the various permutations that can be made. Perhaps someone has already produced what I am about to explain and willing to share?
Basically I face a very tedious train ride each week (3 hours each way) and so thought why not use this time to hone my skills on the flight computer before my ATPL ground exams. I could setup say 50 or so practice questions in excel. The spreadsheet would have an input area that would randomise the numbers that go into the questions and it of course would need to be able to produce an answer sheet as well. To simplify the spreadsheet I guess the questions would need to be in the same order etc but that is no bother.
The overall aim would be to hit a macro button or refresh the random numbers in the questions, walk to the printer in the office and grab my sheets of questions and answers and then off on the train to practice!
Any takers/ideas/criticisms (well hopefully none of those)??
Basically I face a very tedious train ride each week (3 hours each way) and so thought why not use this time to hone my skills on the flight computer before my ATPL ground exams. I could setup say 50 or so practice questions in excel. The spreadsheet would have an input area that would randomise the numbers that go into the questions and it of course would need to be able to produce an answer sheet as well. To simplify the spreadsheet I guess the questions would need to be in the same order etc but that is no bother.
The overall aim would be to hit a macro button or refresh the random numbers in the questions, walk to the printer in the office and grab my sheets of questions and answers and then off on the train to practice!
Any takers/ideas/criticisms (well hopefully none of those)??
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As an information analyst/developer I would be able to help you with the excel but I would think that you would be better using MS access and creating a database because it has much more functionality and you could have a table with all of your questions in and design some nice reports to print them out. This could probably be done in excel but would take 10 times longer.
Unfortunately I havent started studying the flight computer yet (pre PPL) but wouldnt have a problem in helping you design something if someone could provide the data you need.
Regards
Maz
Unfortunately I havent started studying the flight computer yet (pre PPL) but wouldnt have a problem in helping you design something if someone could provide the data you need.
Regards
Maz
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i didnt really read ur post but i believe that OAT have a CRP5 instructuoinal CDROM available for sale.
good luck at staying completely sane in the next few months
good luck at staying completely sane in the next few months
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I have the basic formula for one of the functions of the CRP-5 on excel, if you need. The maths is not simple, but not too involved either. I seem to remember it is heading and groundspeed from TAS/trk/wind, but have not used it in a while - I used it for similar purpose to help me write quesions for the class. If you're interested drop me a PM with email address and I can send it on.
Send Clowns
General Nav Instructor
BCFT
Send Clowns
General Nav Instructor
BCFT
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Thanks for the offers folks.
SC - pm is on its way.
Raz - thanks for that.
Think what I will do is to crib together what I have got in my mind probably in excel since I am crap on access and then open it up for (hopefully) construtive criticism. That way Mazzy if your offer still stands you will be able to at least see what I was attempting to do and then if needed cut, paste, reinvent or whatever into a more user friendly format.
We could well be onto something here that hopefully we can all share in and pass on.
Cheers again for the offers of help.
SC - pm is on its way.
Raz - thanks for that.
Think what I will do is to crib together what I have got in my mind probably in excel since I am crap on access and then open it up for (hopefully) construtive criticism. That way Mazzy if your offer still stands you will be able to at least see what I was attempting to do and then if needed cut, paste, reinvent or whatever into a more user friendly format.
We could well be onto something here that hopefully we can all share in and pass on.
Cheers again for the offers of help.
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Square roots on the CRP5
Hi,
Just trying to get to grips with the old CRP 5 again!
Does anyone have a siple explanation how to work out Square roots with it??
Cheers
Dave
Just trying to get to grips with the old CRP 5 again!
Does anyone have a siple explanation how to work out Square roots with it??
Cheers
Dave