Comparison

Curvature vs pippyg

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Curvature

This app provides advanced tools for calculating and visualizing earth measurements, including curvature, horizon distance, and drop distance. It features a redesigned interface with precision mapping, data persistence, and a knowledge hub with research resources.

Highlights
  • Advanced Earth Calculators
  • Graphic Result Visualization
  • Precision Mapping Tools
  • Data Persistence with SwiftData
  • Expanded PDF Library
  • Universal Unit Converter
  • Save & Export Calculations
Features
Read full description

Curvature is a geometry and visibility toolkit for anyone who wants to test what a curved or flat Earth would predict, with every formula documented and every assumption stated. THE CALCULATOR Enter observer height, target height and surface distance. Curvature returns the surface horizon, tangent-plane drop, midpoint bulge, horizon dip, surface tilt and the hidden and visible portions of the target, in metres or feet, kilometres or miles. Choose refraction off, four published coefficients or your own k from 0 to 0.5, and compare any result side by side with the pure geometric case. Drag the observer, target and distance directly on an exaggerated profile, or switch to a true-scale view with a magnified detail inset. Uncertainty ranges recalculate across your stated input tolerances so you can see whether a sighting is robust. THE MAP Drop rulers and points of interest on standard, satellite or hybrid maps. Rulers report geodesic surface distance and initial bearing in degrees or NATO mils, search for places, fit the view and send endpoints straight to the calculator. Optional terrain lookup prefills ground elevations from SRTM data with the datum and limits spelled out. THE 3D MODEL EXPLORER (NEW) Explore three scenarios with the same observer, date and time: the classical north-polar disc, a south-polar projection comparison and a WGS84 reference ellipsoid. The globe uses dated geometric ephemerides from the open-source Astronomy Engine, including sidereal rotation, precession, nutation, seasons, real Earth-Sun and Earth-Moon distances and lunar illumination, validated against JPL Horizons and US Naval Observatory data. Place the observer anywhere, read elevation, bearing, slant distance and angular diameter for the Sun and Moon, then open the observer sky to see both at their calculated angular size. A comparison sheet lists all three models for the same inputs. Each scene labels what is sourced, what is an app assumption and what is not simulated. REPORTS AND ANALYSIS Export an illustrated PDF report with inputs, coordinates, assumptions, uncertainty bounds and the calculation version, or copy a structured text summary. On supported devices, Apple Intelligence can draft a plain-language analysis that never alters the calculated numbers. REFERENCE LIBRARY Read bundled historical and technical PDFs with page bookmarks, find and go-to. Browse fifty curated web links covering tools, research, forums and video from every perspective, plus references, worked formulas for the calculator, map and explorer, and an indexed glossary of more than eighty terms. YOUR DATA Saved observations, rulers, points, links, imported PDFs and reading positions sync privately through iCloud on signed-in devices, with portable backup and restore. No account, tracking or advertising. Curvature does not tell you what to believe. It shows what each model predicts, how that was calculated and where the model stops.

About

pippyg

Configure your bat recording devices remotely using your phone. Set device IDs, wake/sleep times, and location data. The app uses your phone's microphone to transmit settings to the recorder.

Highlights
  • Configure real-time clock
  • Set device ID
  • Define deployment latitude and longitude
  • Set wake and sleep times
  • Configure PIPPYG bat recorder
  • Configure π•pistrelle bat detector
Features
Read full description

This tool gives you a convenient and reliable method to set the real-time clock, device ID, deployment latitude and longitude, and wake and sleep times for the PIPPYG bat recorder bat detector, in the field, using just your phone and the PIPPYG's onboard microphone. To use the app, set up the configuration you want in terms of Device ID and sleep/wake times, turn your phone volume up to between 1/4 and 1/3 full volume and place your phone's speaker about 4 - 6 inches your PIPPYG's microphone. Now press the Configure / Deploy. SInce the PIPPYG red LED responds to sound after power-up, it flash when your phone makes the "triple chirp" sound. If the LED flashes just when it is responding to the sound, the PIPPYG did not successfully decode the data packete encoded into the chirp, so you need to try again - try changing the phone volume (typically quieter is better), adjust and the distance from the microphone, or positioning the phone more carefully relaive to the PIPPYG - it helps if you point the phone's bottom speakers right at the microphone hole, from a few inches away. If the PIPPYG's red LED flashes 8 times in rapid succession, you have successfully programmed your device, and it will enter a wake/sleep cycle, recording bats (or birds) when it is awake. Note that this app works with both self-build PIPPYG units and with commercially-produced Apodemus PIPPYG and PIPPYG2 devices.

Screenshots

Curvature4 screens
pippyg2 screens

Verdict

The call

The clearest difference is price: pippyg at Free against Curvature's $1.99. pippyg also leads on update cadence (every 2 months vs every 5 months) and iOS requirement (15.6 vs 17.6). Curvature's advantage is rating (5.0 vs 3.7). On ratings volume, ads, in-app purchases and device support there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

pippyg is free to download; Curvature costs $1.99 up front. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

Curvature holds the better App Store score, 5.0 against 3.7. Both are backed by a comparable volume of ratings — 2 and 3 respectively.

UpkeepUpdate frequency

Curvature ships an update every 5 months, pippyg every 2 months. The most recent releases landed on November 6, 2026 and November 3, 2026 respectively.

Scorecard5 real differences · 5 level
Curvature versus pippyg: the parameters behind the verdict, then further details
ParameterCurvaturepippyg
Price$1.99Free — better
Rating5.0 (2 ratings) — better3.7 (3 ratings)
Positive reviews100.0% of reviews—
Number of ratings23 — better
Update frequencyEvery 5 monthsEvery 2 months — better
AdsNoNo
In-app purchasesNoNo
MonetizationPaidFree — better
DevicesiPhone, iPadiPhone, iPad, iPod — better
Requires iOS17.615.6 — better
Further details — not scored
Size116 MB3 MB
Age rating4+4+
DeveloperSteven WilkinsonPhil Atkin

Customer experience

Curvature

All ratings2 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews2 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

pippyg

All ratings2 ratings
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

None

Curvature

No in-app purchases

None

pippyg

No in-app purchases

Questions

Is Curvature free?
Curvature costs $1.99, with no in-app purchases.
Is pippyg free?
pippyg is free to download, with no in-app purchases.
Which has better reviews, Curvature or pippyg?
Curvature is rated higher. Curvature averages 5.0 out of 5 from 2 ratings, while pippyg averages 3.7 from 3 ratings.
Do Curvature or pippyg have ads?
Neither Curvature nor pippyg shows ads.
Which is updated more often, Curvature or pippyg?
Curvature ships an update every 5 months, and pippyg every 2 months. Most recently, Curvature was updated on November 6, 2026 and pippyg on November 3, 2026.

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