Beta Test Request - MyCloudBase iOS App for Glider Pilots

[Matt Herron]

Here's a beta tester brief for your glider group:

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What if you could point your phone at a CU and determine its distance and how much altitude you would lose getting there?

Fellow soaring pilots,

I've been working on an iPhone app called MyCloudBase that does exactly that. It's sort of a "one trick pony," but it might be a pretty good trick for cross-country flying.

What it does:

• Point your camera at a cloud base
• See real-time distance and altitude loss calculations
• Uses your glider's L/D ratio and current altitude
• Shows a "reachable terrain" overlay based on your glide performance
• All calculations use the phone's sensors and camera to measure angles accurately

How it works: The app uses your phone's accelerometer to track the horizon and calculates the angle to the cloud base. Combined with the cloudbase altitude and your current altitude, it gives you horizontal distance and expected altitude loss. It's been calibrated with laser levels for accuracy.

Why I need your help: I'm vibing this code (learning as I go!) and would really appreciate feedback from experienced pilots. I'm particularly interested in calibration results for different iPhone models - if you find the horizon line doesn't track perfectly with a known level reference, let me know your calibration values and iPhone model so I can build them into the app.

Beta Test Details:

• 25 slots available via TestFlight
• IMPORTANT: You must click this link FROM YOUR IPHONE (not desktop/iPad) or you'll only get a simulator version
• TestFlight Link: https://testflight.apple.com/join/YGt7njS4

Quick Start Guide:

1. Install the app via TestFlight link above
2. Allow camera and location permissions when prompted
3. Set your glide ratio:
   • Tap "Glide Ratio" button at bottom
   • Spin the wheel to your typical L/D (e.g., 35:1 for a typical sailplane at cruise speed, minus any safety margin you want)
4. Set cloudbase altitude:
   • Tap "Cloudbase" button
   • Spin the wheel to estimated cloudbase in feet MSL
5. Point at a cloud:
   • Aim the crosshair at the cloud base
   • Green box shows reachable terrain area
   • Distance and altitude loss appear when crosshair is above horizon
6. Capture the reading:
   • Tap the capture button at bottom to save the measurement

Tips:

• The black "Horizon" line should stay level with the real horizon - this is key to accuracy
• If the crosshair shows an up arrow, tilt the phone upward
• You can toggle distance units (sm/nm/km) and altitude units (ft/m) in Settings
• For expert calibration adjustment, enable "Show Horizon Calibration Controls" in Settings

What I'm looking for:

• Does the horizon line track accurately when you tilt/roll the phone?
• Are the distance calculations reasonable/useful?
• UI feedback - is it usable in the cockpit?
• Your iPhone model and any calibration adjustments needed
• General bugs, crashes, or weirdness
• Ideas for improvements
• best use case or target audience
• suggested price point

Looking forward to your feedback! You can reply here, or use the feedback feature in TestFlight after using the app.

Clear skies and happy soaring,

Matt

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P.S. Remember to click the TestFlight link from your iPhone, not a computer!

[Matt Herron]

Hi beta testers,

Thanks for trying out MyCloudBase! Here's how to calibrate the horizon line for maximum accuracy. Your calibration values will help all future users - I can bake them into the app so everyone with your iPhone model gets perfect accuracy right out of the box.

---

METHOD 1: Using a Distant Horizon (Easiest)

Best for: Ocean, large lake, flat desert, or any clear distant horizon

Steps:

1. Enable calibration controls in Settings → Advanced Settings → "Show Horizon Calibration Controls"
2. Point the camera at the distant horizon
3. Adjust the OFFSET slider until the black "Horizon" line in the app aligns with the true horizon
4. Tilt the camera upward so both the true horizon and the app's horizon line are visible near the bottom of the screen
5. Adjust the SCALE slider until the horizon line stays aligned with the true horizon throughout the tilt
6. Check the offset again and adjust if needed
7. Note the values (Portrait Scale and Portrait Offset numbers)
8. Tap "Save"

---

METHOD 2: Using a Laser Level (Most Accurate)

Best for: Indoor calibration, or when no distant horizon is available

Important setup:

• The laser must hit at least two surfaces at different distances (like shining through a doorway down a corridor)
• This creates a visible laser line you can use as a reference

Steps:

1. Enable calibration controls in Settings → Advanced Settings → "Show Horizon Calibration Controls"
2. Set up your laser level horizontally
3. Shine it through a doorway or across multiple surfaces so you can see the laser line at near and far distances
4. Point the camera at the laser line
5. CRITICAL: Move the camera up or down until ALL visible laser reference points line up in the camera view - this ensures the camera lens is exactly on the plane of the laser
6. Adjust the OFFSET slider to align the black "Horizon" line with the laser line
7. Tilt the camera upward while keeping the laser line visible near the bottom
8. Adjust the SCALE slider until the horizon line stays aligned with the laser line throughout the tilt
9. Note the values (Portrait Scale and Portrait Offset numbers)
10. Tap "Save"

---

What to Report Back:

Please post your results with:

• iPhone Model (find in Settings → About → "Device")
• Portrait Scale: (e.g., 0.917)
• Portrait Offset: (e.g., -3 pixels)

Example:

iPhone 14 Pro Portrait Scale: 0.943 Portrait Offset: 14 pixels

---

Why This Matters:

Once I have calibration data for various iPhone models, I can build those values into the app as factory defaults. Future users with your phone model will get perfect accuracy immediately - no calibration needed!

So far I have calibrated:

• iPhone 15 Pro
• iPhone 13 Pro
• Your contribution helps everyone. Thank you!

Clear skies,

Matt

---

Note: You only need to calibrate in Portrait orientation. The app is locked to portrait mode for simplicity.

[Lawrence Spinetta]

interesting idea. Android version available?

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[Matt Herron]

Sorry, no Android version at this time.  Also currently not built for iPad, although that is possible if there is demand.

Matt

[Eric Greenwell]

It's interesting, but I can make that distance estimate using the distance rings on my Oudie N. If I can see a cloud shadow, I can look on the map for the corresponding location to get the distance; or, I can turn on the satellite image, find the cloud I'm interested in, and note it's distance. These seem like they easier than holding up phone to make the measurement, but they have their own issues, and I don't know how easy your method is to use, It'll be about three months before I fly again, so plenty of time to wait for reports.

[Stefan Will]

Do the satellite images really update frequently enough to be able to identify individual clouds at their current position in real time?

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[*Eric Greenwell1*]

Yes, the update seems to be often enough that I can find the correct cloud on the image.

It's supposed to be a 10 minute update cycle, but I don't know the age of image when it actually appears on the Oudie. In practice, I've been able to locate the cloud in the image that I'm looking at from the cockpit. But, if it's windy, say 20+kts, there might be enough drift to fool me. Also, if it's a small cloud (<1 mile across), it might be hard to see on satellite photo.

Eric

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[Matthew Scutter]

If you are using the SkySight satellite photos they're approximately 13 minutes behind realtime - taking the imagery takes 9 minutes, it gets to us after ~2 minutes, and we convert it from raw radiances to the imagery you see and upload it in ~2 minutes. Pretty close to as fast as theoretically possible.

They are then on a 10-minute interval on the Oudie and 15-minute on the LX.

We do actually produce on a 5-minute interval for the US but no one has integrated that into their devices yet.

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[ma...@digitalshorts.com]

I assume you need a real time internet connection for this to work?

BTW, you can try the app without flying.  Just point it above the horizon to get a feel for how it works.  Super simple.

Matt

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[*Eric Greenwell1*]

Yes, you do. I use a "data only" SIM card in my Oudie N that can access Verizon, AT&T, and T-Mobile cellular networks (whichever is strongest in the current location) to get the SkySight images (besides the satellite images, it can download some of the other SkySight forecasts). Cost is about $9 for 2GB/month, which is way more than I use.

Eric

[Moshe Braner]

A big problem with this concept is that the altitude of cloudbase is assumed known, presumably the same as experienced recently.  But at least in the NE US on a decent summer day the altitudes of the bases of different clouds vary significantly, over space and time.  Presumably they depend on recent local rainfall etc.  Maybe they are more uniform in drier climates.  And/or small difference are less important when cloudbases are higher than they are here.

On Sunday, December 28, 2025 at 1:07:56 PM UTC-5 ma...@digitalshorts.com wrote:

Here's a beta tester brief for your glider group:

---

What if you could point your phone at a CU and determine its distance and how much altitude you would lose getting there?

Fellow soaring pilots,

I've been working on an iPhone app called MyCloudBase that does exactly that. It's sort of a "one trick pony," but it might be a pretty good trick for cross-country flying.

What it does:

• Point your camera at a cloud base
• See real-time distance and altitude loss calculations
• Uses your glider's L/D ratio and current altitude
• Shows a "reachable terrain" overlay based on your glide performance
• All calculations use the phone's sensors and camera to measure angles accurately

How it works: The app uses your phone's accelerometer to track the horizon and calculates the angle to the cloud base. Combined with the cloudbase altitude and your current altitude, it gives you horizontal distance and expected altitude loss. It's been calibrated with laser levels for accuracy.

...

[Sławomir PIela]

Nice project!

However if I understand correctly we need to know and once in a while need to provide exact cloudbase. Possible by thermaling to the ceiling and we are good for some time (assuming the weather does not make cloudbases jittered over relatively short distance). When mountain flying having something like PeakVisor would give us quite exact distance to a peak, angle to the edge can be more or less measured and cloudbase could be calculated. This will not work in flat terrain unless we have some obvious markers on the ground. 

Project deserves more thought and development! Good luck. 

Wiadomość napisana przez Moshe Braner <moshe....@gmail.com> w dniu 30 gru 2025, o godz. 22:49:



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[Matt Herron]

Hi Moshe.

I am thinking of this app as more of a training tool for new XC pilots, or students that need some experience estimating distances to clouds, and also the cost in altitude getting to those clouds.  Experienced XC or competition pilots already have these skills, and probably won't benefit.  The reachable terrain area is also good for beginners and doesn't depend on knowing cloudbase.  They sometimes find it difficult to estimate their glide angle early on.  When I teach new XC pilots, I sometimes put a chart on the wall with various lines for glide slopes drawn.  When you stand at the correct distance you can hold your fingers at arm's length as a reference that can be later used in the cockpit to determine reachable terrain.  Same thing, just now an electronic (and slightly more accurate) version.

I agree that cloudbase does vary.  Perhaps less in the Sierras where I fly.  Even then you can expect cloudbase to climb over the course of the day.  Hopefully you reach cloudbase often enough to adjust the setting.  That's why I made the altitude adjustment a pick wheel you can just roll with a finger for easy tweaking in flight.

Matt

[Moshe Braner]

The important question for inexperienced pilots - and experienced ones too - is not whether you can reach a cloud, but whether you can reach a safe landing spot in case that cloud (or whatever) does not yield the expected lift.  That we can already read from a glide computer.  Assuming it is configured and interpreted correctly, which is what I try and teach.

[David S]

Yes, and by the same token, you want to know if safe landing spots are reachable from the next cloud.  For that, it's useful to know your expected altitude upon reaching the cloud.  This app should be of some help there.

   ...david

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[Charles Mampe]

I sorta agree on the use of a glide computer, but I don't believe this is the target for this app. None of our club ships have glide computers, most don't even have audio varios.

Flight logging is "See you navigator" on a smartphone.

Thus, this app could be a nice addition to the toolbox.

My only caution is to not get wrapped up in doing things with a smartphone, keep your head outside. I don't use various things in See you so that I keep looking outside and I want students to do the same. If they aren't doing frequent hour plus flights, they don't need more distractions.

Just my $0.05 (pennies are getting hard to find).

[Ian Molesworth]

21st century and cllub ships without audio varios! Pretty astonishing. 

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[Eric Greenwell]

Yes, it seems like varios with audio would be important "to ... keep your head outside". My suggestion, since at least someone in the cockpit is using Navigator, is add a vario widget to the flight page to gain the audio function.

Eric

[christopher behm]

100% agree. 

The club ships at my club have no batteries. It was a tooth and nail fight just to get 1" ram balls (and I purchased the balls and hardware to mount, donating to the club, so zero cost to them) mounted to the dash. 

Why did I want them? To put a phone mount for FREE XC Soar (which has an audio vario function and yes it works pretty well). 

I was told that the phone would be a distraction for students. I replied you could flip the phone screen forward, no distraction. 

Is it more distracting watching a static vario to stay up, or looking outside as you should be, listening to an audio vario?

I think we all know the answer, and it's in every textbook about thermalling...

Just because someone was taught to do things a certain way 50 years ago, does not make a more up to date way "unsafe". 

This year it will be 2026. Should we be trained to fly by sight? Sure. Should be be trained to only be able to fly by sight? I don't think so. 🤔 

Sent from my T-Mobile 5G Device
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Sent: Wednesday, December 31, 2025 7:57:09 AM
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Subject: Re: [RAS_Prime] Re: Beta Test Request - MyCloudBase iOS App for Glider Pilots

 

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[two vallhunds]

I suppose trying on an antique iPhone SE would not be much help.

[christopher behm]

XC Soar is now in the apple store. This just happened a month or two ago. 

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