4 ms·

> For example it's crazy that most pilots are still taught to calculate W&B using printed charts and approximate takeoff performance. We're taught that so we k

> For example it's crazy that most pilots are still taught to calculate W&B using printed charts and approximate takeoff performance. We're taught that so we know what we're doing. Then we open our iPhone app (EFB or electronic flightbag) and do it there. In fact, part of the reason we do it there is because most of them phone home to their maker and log that we did it. So if there's an accident people can know "well they did their W&B" > the rest of the things Regulations have made aviation so expensive that it's ridiculous. A lot of airplanes flying today are flying with their same avionics from 60 years ago because upgrading is expensive. To get the gas calculation you mention would require a certified GPS (on the low end from Garmin that's $6,000) and an engine monitor ($5,500 from Garmin), plus installation costs of another few thousand dollars. Most planes have a gear down warning (ie, 3 indicator lights) but their original "bitching betty" is hard to hear because we now wear ear protection when we fly and have noise cancelling headphones. You probably can't even integrate that with a new Garmin system because they've gone full encrypted CANBUS to lock out integrations. re: spin warnings - not sure what to tell you there. Stall speed is based on weight and configuration (flaps) and 99% of GA planes have no idea what they weigh or if their flaps are deployed. But again, it's not that we can't do those things, it's just that they're completely cost prohibitive. Getting anything certified today is a flippin' nightmare and at too high of a cost to ever break even.

TylerE 2y ago
Stall speed is a misnomer. Stalls occur due to exceeding the critical angle of attack and can happen at ANY speed.
- echoangle 2y ago
  I think that was his point. To calculate if you are going to stall in a final, you need to know your weight and flap setting to see if you will exceed the critical angle of attack when doing the turn, exactly because the speed isn’t constant.
  - lovecg 2y ago
    No, you just need an angle of attack sensor. These are increasingly available for small GA planes.
    - blt 2y ago
      stall AoA depends on flaps though?
      - lovecg 2y ago
        Yes, and some sensors do take flaps position into account (or you compromise and have it display the AoA with a typical approach setting).
    - echoangle 2y ago
      You need an AoA sensor to see if you are currently stalling or are just about to stall. To predict if you will stall at a specific point in your approach before you’re there, you need to know your weight, too.
- the__alchemist 2y ago
  Whoever is downvoting this: Stop. It's the key point here. Planes don't need to know their weight to produce a stall warning; AoA is a great metric, and GA planes not having an indicator or warning based on it is astonishing.
  - echoangle 2y ago
    I thought the point was predicting a stall by knowing the approach speed will be so low that you will stall, not detecting a stall just before it happens
    - Onavo 2y ago
      You can't control the weather, if there's a micro burst during landing you are in trouble.
  - FabHK 2y ago
    GA planes have a stall warning horn (based on AoA). They just generally don't have a AoA indicator (though that might be a good idea indeed), relying on indicated airspeed instead, which (for given airplane mass) has a one-to-one [1] mapping to AoA in unaccelerated flight. That's why the concept of stall speed exists. That is the case since, in unaccelerated flight, we need weight == lift, so W := m g == L := 1/2 rho v^2 c_L S with m = mass, g = earth gravitational acceleration, 1/2 rho v^2 = fluid dynamic pressure which is measured by the pitot tube and displayed as indicated airspeed (well, a function of it), c_L = the coefficient of lift, and S = wing area. Now, weight is constant (for given airplane mass, in unaccelerated flight), and so is the wing area. The coefficient of lift depends on the AoA, and dynamic pressure has a monotonic one-to-one relationship to IAS. Thus you have the relationship between IAS and AoA. [1] Unless you get to "the back of the power curve" (the coefficient of lift increases with AoA, then decreases again, until it drops off in a stall). Let's not go there.
- iamtheworstdev 2y ago
  it's a misnomer but airspeed is life. we're not talking about people stalling during air combat or aerobatics, we're talking about doing it in the pattern. simply keeping your speed up and knowing the speed you will stall at based on bank angle should be enough.
bjornsing 2y ago
> But again, it's not that we can't do those things, it's just that they're completely cost prohibitive. Isn’t this what the OP is referring to when he says the current market can’t support the necessary innovation? As I understand it the idea here is to expand the market and spread certification costs out over more planes.
- bluGill 2y ago
  I don't think he can get the required certifications and charge a reasonable price for this plane. There are not enough people interested in a personal airplane at any price to support the costs to bring a new one in the air. You can rebuild all current airplane's (most built before 1980) for much less than the costs to certify a modern replacement, and only then can you start asking what it costs to build that replacement. Which is why we rebuild old airplanes all the time - it is wouldn't pass modern regulations but since it already exists it is certified.
  - n_ermosh 2y ago
    There's an interesting dynamic here--we (the industry today) are more okay with flying rickety airplanes from the 70s before flying something built with more modern engineering and production techniques. > As I understand it the idea here is to expand the market and spread certification costs out over more planes. exactly. > There are not enough people interested in a personal airplane at any price to support the costs to bring a new one in the air. our thesis is that this isn't true. we've seen glimpses of this in the past 10 years that haven't been successful, but have shown that there is a wave of people who would get into GA if it were safer and more affordable. our mission to make it so, and the Airhart Sling is just the first step
    - bluGill 2y ago
      I'm not wishing you bad luck, but I remain pessimistic about your ability to get something certified and charge a reasonable price.
    - lovecg 2y ago

TylerE 2y ago

Stall speed is a misnomer. Stalls occur due to exceeding the critical angle of attack and can happen at ANY speed.

echoangle 2y ago
I think that was his point. To calculate if you are going to stall in a final, you need to know your weight and flap setting to see if you will exceed the critical angle of attack when doing the turn, exactly because the speed isn’t constant.
- lovecg 2y ago
  No, you just need an angle of attack sensor. These are increasingly available for small GA planes.
  - blt 2y ago
    stall AoA depends on flaps though?
    - lovecg 2y ago
      Yes, and some sensors do take flaps position into account (or you compromise and have it display the AoA with a typical approach setting).
  - echoangle 2y ago
    You need an AoA sensor to see if you are currently stalling or are just about to stall. To predict if you will stall at a specific point in your approach before you’re there, you need to know your weight, too.
the__alchemist 2y ago
Whoever is downvoting this: Stop. It's the key point here. Planes don't need to know their weight to produce a stall warning; AoA is a great metric, and GA planes not having an indicator or warning based on it is astonishing.
- echoangle 2y ago
  I thought the point was predicting a stall by knowing the approach speed will be so low that you will stall, not detecting a stall just before it happens
  - Onavo 2y ago
    You can't control the weather, if there's a micro burst during landing you are in trouble.
- FabHK 2y ago
  GA planes have a stall warning horn (based on AoA). They just generally don't have a AoA indicator (though that might be a good idea indeed), relying on indicated airspeed instead, which (for given airplane mass) has a one-to-one [1] mapping to AoA in unaccelerated flight. That's why the concept of stall speed exists. That is the case since, in unaccelerated flight, we need weight == lift, so W := m g == L := 1/2 rho v^2 c_L S with m = mass, g = earth gravitational acceleration, 1/2 rho v^2 = fluid dynamic pressure which is measured by the pitot tube and displayed as indicated airspeed (well, a function of it), c_L = the coefficient of lift, and S = wing area. Now, weight is constant (for given airplane mass, in unaccelerated flight), and so is the wing area. The coefficient of lift depends on the AoA, and dynamic pressure has a monotonic one-to-one relationship to IAS. Thus you have the relationship between IAS and AoA. [1] Unless you get to "the back of the power curve" (the coefficient of lift increases with AoA, then decreases again, until it drops off in a stall). Let's not go there.
iamtheworstdev 2y ago
it's a misnomer but airspeed is life. we're not talking about people stalling during air combat or aerobatics, we're talking about doing it in the pattern. simply keeping your speed up and knowing the speed you will stall at based on bank angle should be enough.

bjornsing 2y ago

> But again, it's not that we can't do those things, it's just that they're completely cost prohibitive. Isn’t this what the OP is referring to when he says the current market can’t support the necessary innovation? As I understand it the idea here is to expand the market and spread certification costs out over more planes.

bluGill 2y ago
I don't think he can get the required certifications and charge a reasonable price for this plane. There are not enough people interested in a personal airplane at any price to support the costs to bring a new one in the air. You can rebuild all current airplane's (most built before 1980) for much less than the costs to certify a modern replacement, and only then can you start asking what it costs to build that replacement. Which is why we rebuild old airplanes all the time - it is wouldn't pass modern regulations but since it already exists it is certified.
- n_ermosh 2y ago
  There's an interesting dynamic here--we (the industry today) are more okay with flying rickety airplanes from the 70s before flying something built with more modern engineering and production techniques. > As I understand it the idea here is to expand the market and spread certification costs out over more planes. exactly. > There are not enough people interested in a personal airplane at any price to support the costs to bring a new one in the air. our thesis is that this isn't true. we've seen glimpses of this in the past 10 years that haven't been successful, but have shown that there is a wave of people who would get into GA if it were safer and more affordable. our mission to make it so, and the Airhart Sling is just the first step
  - bluGill 2y ago
    I'm not wishing you bad luck, but I remain pessimistic about your ability to get something certified and charge a reasonable price.
  - lovecg 2y ago