"Flying the field"....Broad Experience Input from YOU!

[MarsLander]

As some know, Long time BABABAR. Lots of LPR, some mid, some high. L1 around 2000. Back at it with L2 this spring/LDRS (see Viper build link in signature).

I now have a 1500'x1500' (Red Box) field about 5 minutes from home. Tree line at the south end (right behind Green X), with another 600" directly south and 750' to the east, or so of open field behind the trees to the south/east (yellow box). I can fly from anywhere on the field, depending on the winds.



I'm re-learning to "fly the field."

We spent the day on Sunday learning the new field and re-learning how to "fly the field." Winds were about 5-10 out of the south east, launching on the south end of the field (green X). Upper level winds were much faster than surface winds (more on that later). First flight, flew to the south and recovered behind the tree line to the south (in the Yellow Box). Oh...yeah...point downwind to have a vertical launch. DUH! Check!

Probably another 10 launches or so were great, Point it downwind about 5 degrees, great vertical launches most recovery within 2-400', including a Cherokee-E on a C6-5. All good.

Last launch of the day, loaded up the Cherokee with an E-12. Send it!...or so I thought. Right...with a 15" parachute. See ya! Ended up at the red X, or there abouts! As my mother would say, "that's the price of an education!"

Again, this is about learning to fly the field. I have my own thoughts, which I will share here, would LOVE to hear your thoughts about flying the field!

1. The field is a hay field. It is not hard, but VERY soft, and the geographic area is generally wet (all the time). It would be easy to fly this field with streamers and will experiment with simple streamer recovery, or much reduced parachute sizes. We had one deployment that didn't eject the parachute and came in hot. The CA at the end of the tube protected it from damage.
2. Leverage Rocksim/OpenRocket to do simulations of descent rates and G. Harry Stine parachute CD rates (1.09), with wind forecasts to figure out parachute sizes to stay within the field. (p. 186 Handbook of Model Rocketry 7th edition from Top Flight). Also using a 1 piece launch rod and measure launch angles (entered into rocksim) to launch into the wind and predict landing locations.
3. Use Windy and GPS drift calculations (https://www.rocketryforum.com/threa...-predictor-and-visualizer-spreadsheet.165859/). Though for the Cherokee-E, there isn't much altitude discrimination (it goes from 330ft to 200ft in one step), and likely apogee was 1600'...it was a nice vertical flight!

For a L2 flight, I think approach 3 would be a good route. How much launch angle discretion are you allowed when setting up a 1515 rail? I understand that the field and the spectator location is a big input to launch location and angles...how much adjustability and discretion is allowed to the flier?

Thanks for your help and insights!

MarsLander.

 

[lr64]

Is this why some people go ridiculously large instead of ridiculously high for their certification?

Dual deploy?

 

[Voyager1]

As some know, Long time BABABAR. Lots of LPR, some mid, some high. L1 around 2000. Back at it with L2 this spring/LDRS (see Viper build link in signature).

I now have a 1500'x1500' (Red Box) field about 5 minutes from home. Tree line at the south end (right behind Green X), with another 600" directly south and 750' to the east, or so of open field behind the trees to the south/east (yellow box). I can fly from anywhere on the field, depending on the winds.

View attachment 634005

I'm re-learning to "fly the field."

We spent the day on Sunday learning the new field and re-learning how to "fly the field." Winds were about 5-10 out of the south east, launching on the south end of the field (green X). Upper level winds were much faster than surface winds (more on that later). First flight, flew to the south and recovered behind the tree line to the south (in the Yellow Box). Oh...yeah...point downwind to have a vertical launch. DUH! Check!

Probably another 10 launches or so were great, Point it downwind about 5 degrees, great vertical launches most recovery within 2-400', including a Cherokee-E on a C6-5. All good.

Last launch of the day, loaded up the Cherokee with an E-12. Send it!...or so I thought. Right...with a 15" parachute. See ya! Ended up at the red X, or there abouts! As my mother would say, "that's the price of an education!"

Again, this is about learning to fly the field. I have my own thoughts, which I will share here, would LOVE to hear your thoughts about flying the field!

1. The field is a hay field. It is not hard, but VERY soft, and the geographic area is generally wet (all the time). It would be easy to fly this field with streamers and will experiment with simple streamer recovery, or much reduced parachute sizes. We had one deployment that didn't eject the parachute and came in hot. The CA at the end of the tube protected it from damage.
2. Leverage Rocksim/OpenRocket to do simulations of descent rates and G. Harry Stine parachute CD rates (1.09), with wind forecasts to figure out parachute sizes to stay within the field. (p. 186 Handbook of Model Rocketry 7th edition from Top Flight). Also using a 1 piece launch rod and measure launch angles (entered into rocksim) to launch into the wind and predict landing locations.
3. Use Windy and GPS drift calculations (https://www.rocketryforum.com/threa...-predictor-and-visualizer-spreadsheet.165859/). Though for the Cherokee-E, there isn't much altitude discrimination (it goes from 330ft to 200ft in one step), and likely apogee was 1600'...it was a nice vertical flight!

For a L2 flight, I think approach 3 would be a good route. How much launch angle discretion are you allowed when setting up a 1515 rail? I understand that the field and the spectator location is a big input to launch location and angles...how much adjustability and discretion is allowed to the flier?

Thanks for your help and insights!

MarsLander.

You’ve identified wind and descent rate as important parameters for flying the field, but don’t forget motor impulse as an important factor in controlling altitude. Simulations are very useful, but should be used with accurate simulation model parameters.

At the beginning of the launch session on a small field, start with a low impulse launch to get an idea of the drift.

As for HPR launch rail/rod angles, the Tripoli requirement is for no more than 20 degrees off vertical, and only with the RSO’s approval. Never tilt towards the spectator and launch control areas.