Mvelez

Hello:

I've been getting interested on buying an Eagle Tree to be able to get some data about:

upline speeds
downline speed (and be able to better adjust motor brakes and biplane airprakes)
cruise speeds
baseline consistency
flight depth
60° elevation rule

and of course maneuver geometry.

I wrote Eagle Tree's tech support for a product recomendation and got inmediate response:

" Marcelo,

Our eLogger and GPS expander should be able to show you what you want as it will be able to plot the flight in Google Earth after the flight. It can also record GPS speed (ground speed) and GPS altitude and other parameters such as voltage, amperage and airspeed (if you purchase an the airspeed sensor)

However, the GPS info is only as good as the quality of the fix it has which is determined by how many satellites it has locked. A problem may arise when you are flying at any attitude other than straight and level. When not straight and level the GPS will not have an optimum view of the sky and will lose accuracy.

So unfortunately I can't guarantee that you will get data that will be accurate enough for your purposes. I suggest researching online to see if there are any users that have similar setups and see what performance they are reporting."

So here I am doing the homework: has anybody using these systems had any problems with gps tracking while on inverted, knife edge, loop tops, etc? is this something I should worry about? any product recomendations here?

Help is appreciated!

Marcelo Velez

EHFAI

Marcelo

I've used the Eagle Tree Pro logger with various sensors to gather data of pattern flights for many years. I agree with ET that the altitude data from the GPS will likely not provide the info you need. GPS is great for gathering horizontal data including track and ground speed, but be aware that those data are only relevant in level flight. Obviously, the ground speed diminishes to the GPS in climbing or diving - great for up wind / down wind level flight speeds though. The track is very useful when input to Google Earth to observe / measure distance out / parallel w runway / geometry of rollers / etc. (See FAI rolling circles thread by OhD.)

The ET baro altitude and airspeed data gathered from their pitot tube (placed outside the propwash) are quite useful and pretty accurate. I typically note the key points (taken from ET graphics) onto Arresti of the sequence, which provides much of the info you're interested in. These data allow a check of entry / exit altitudes, cross-over altitudes of 8's / hourglass / etc. The speed data are airspeed which will be affected by wind speed - the wind speed is irrelevant on up / down lines and provides useful info on power / props / braking / etc. So both pitot and GPS ground speeds are useful is used properly.

The ET equipment is well made and their service / support is outstanding. While it takes more time than a flight to analyze the data, there's lots of info available. Their E-logger is very useful for gathering E power data and can handle lots of the Pro level sensors also.

n233w

I know nothing about this equipment other but I have long thought that such info would be helpful for pattern practice.

What about RCLogger? GPS, Orientation, etc. are available. I believe their stuff is comparable.

Portlandflyer

This looks interesting for a hundred bucks:

https://www.commonsenserc.com/produc...1p3hqtqphqh911