Letters: November 2012

ADS-B Portables
I am not clear about the options for interfacing ADS-B portable receivers (September Aviation Consumer) with various software and platforms.
Do the receivers output a standardized string, be it by cable, Wi-Fi or Bluetooth, that can be received and utilized by any software and platform as long as the software contains ADS-B receiver support? Or is data output unique to each manufacturer?

For example, as far as external GPS receivers are concerned (most of them use Bluetooth), as long as the software supports external GPS (via Bluetooth in this case), one should generally be able to use any GPS receiver, regardless of software publisher or platform.

Via e-mail

Portable ADS-B receivers are paired with compatible applications. It doesn’t matter whether it’s an Android or Apple platform, so long as the application is compatible with the functionality of the ADS-B unit. For example, Garmin’s GDL39 portable ADS-B works with a variety of Garmin portable GPS units, with some limitations in traffic, while full functionality is achieved with Garmin’s Pilot application.

SkyRadar has the SkyRadar application, while Sporty’s Stratus is designed around the ForeFlight app.
We believe it is best to decide which application works best for you before buying a receiver.

I just read the article on GAMIjectors in the October issue and saw something that doesn’t match my understanding of what GAMIjectors do. It is said that they allow each cylinder to receive the same amount of fuel. I thought they were designed to correctly match the amount of fuel necessary to match the amount of air delivered to each cylinder by the induction system.

It’s my understanding that most induction systems don’t provide equal air flow to each cylinder and therefore the fuel/air ratio varies from cylinder to cylinder. By matching fuel flow to air flow, GAMIjectors maintain a correct fuel-to-air ratio among the cylinders.

It’s my understanding that by doing this matching, the power produced by each cylinder differs slightly among the cylinders on an engine, but the fuel-to-air ratio is made equal. This is confirmed by EGTs peaking at the same fuel flow and is accomplished by adjusting the fuel flow to each cylinder as necessary with highly calibrated fuel injectors.
Am I wrong or have I just missed something in my research on the value of LOP using GAMIjectors on my Continental IO-520 in my V35B Bonanza?

Ted Sigtenhorst
Via e-mail

The statement that GAMIjectors allow each cylinder to receive the same amount of fuel is correct. The airflow to each cylinder is determined by the volumetric efficiency of each cylinder and is, in no way, related to the fuel injection system. As a rule, the airflows match fairly well. That has nothing to do with why GAMIjectors were invented.
The problem faced was the log-runner induction plumbing of the Continental large-displacement engines. The fuel injection system is “constant flow,” and some of the fuel that is being delivered to the rear cylinder induction ports moves back into the induction system and then forward to the next cylinders in the line. That’s why the rear cylinders tend to run leaner and the forward richer. GAMIjectors address this by sending less fuel to the middle and forward cylinders, in the correct amounts, to result in balanced fuel/air ratios.

XM, Radar Disagreement
In the August issue article, Radar Upgrades, you described a disturbing incident involving a significant disagreement between the XM NEXRAD data and the on-board aircraft radar. Do you know why there was a disagreement? Was the XM image older than five minutes? I replaced my GPSMAP 496 with a factory-overhauled 496 (Garmin suspected that the internal clock in my original 496 was a bit “off “ and was rejecting new images). The factory-overhauled 496 works better, but it occasionally (and always at the worst time) stops updating for 10 or more minutes.

David Ansley
Nokomis, Florida

The XM data was coming in through a HeadsUp XMD76A receiver, playing on an Avidyne EX500 MFD. The time stamp on the NEXRAD data flow was around six minutes, and I’m not sure it updated for a good 10 minutes or so. Long before that, we were spinning the knobs on the ship’s radar and looking at the buildups with our eyeballs.

Paul’s Departure
What a disappointment it is to learn that Paul Bertorelli is departing the editor position. His depth of knowledge and breadth of experience is probably irreplaceable.

Charles Keen
Boynton Beach, Florida

Paul, thank you for the great job you have done. Good luck with your future projects. I was pleased to learn you’ll still be involved with Aviation Consumer.

Paul Hollowell
Venice, Florida

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