October 28, 2007 at 8:52 pm #662airtrampParticipant
There was a recent question from Benzin on why we want to have a bell shaped power curve which caused me to think about putting the answer in a format that may help others like myself that find it easier to learn with visual signals better than words.
Following are some cooked up numbers to demonstrate the rational behind a bell shaped curve being better (more shots) than a constantly falling curve. Iâ€™m using some assumptions also :
1. A constant string of 5 shots for each scenario.
2. Precedent and subsequent shots will vary by 2 fps each.
Bell Curve . . . Falling Curve
1) 890 . . . . . . . 920
2) 892 . . . . . . . 918
3) 894 . . . . . . . 916
4) 896 . . . . . . . 914
5) 898 . . . . . . . 912
6) 900 . . . . . . . 910
7) 902 . . . . . . . 910
8/ 904 . . . . . . . 910
9) 906 . . . . . . . 910
10) 908 . . . . . . 910
11) 910 . . . . . . 908
12) 910 . . . . . . 906
13) 910 . . . . . . 904
14) 910 . . . . . . 902
15) 910 . . . . . . 900
ES = 20 . . . . . . 20
The constant velocity section is when all the variables of the pcp action are at the optimum.
You can see that both curves have an extreme spread of 20 fps but the shot counts are quite different.
Often, a falling curve may not even have a noticeable constant velocity section and if the curve is steep, you will see a POI shift every 5-6 shots if you are shooting anywhere beyond 40-50yd.
Some well engineered pcp like the Air Arms can get a relatively long constant velocity string (i.e. more than 5 shots) so they will have a useful total shot count of 30-35 within that 20 fps range.
If the above is all BS, don’t hesitate to let me know. I’m just hoping to help other newbies like myself to get a better grasp of the science of the dark side.November 13, 2007 at 5:42 pm #27590walkonkingParticipant
Thanks for that post. I dont know how I missed it before.
Nice work and a good numbers to work with.November 13, 2007 at 8:47 pm #27600yParticipant
Thanks for explaining that so well Tramp…November 14, 2007 at 11:19 am #27630poiParticipantquote AirTramp:
I hope you don’t mind if I post this somwhere else as well, with full credit of course. Well said!November 14, 2007 at 5:04 pm #27640airtrampParticipant
Hey POI, not at all. The whole idea is to help others so feel free to post anywhere you want.November 14, 2007 at 10:10 pm #27645anthony266Keymaster
Great job Tramp.
Thank YouNovember 15, 2007 at 12:54 am #27654bodhisdadParticipant
This is the perfect setup, but requires the right balance of hammer weight and valve spring compressive weight. I’m going to mess with this issue this winter as work gets slow. WIll post what i find, definately an advantage to have a slight curve as posted. I’m not far off and just have to try a couple of combinations as well as the time. Its doable and the POI wouldn’t suffer, it will be a fun experiment.
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