Too Slow for Apogee?

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Blackbird1936

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Hi, I have an old Estes Phonix that was always a contentious flyer ( especially on Estes Motors ) Needed a lot of umph and a very short delay. Recently pulled from the closet and added a section of body tube to lengthen to make it fly better in the wind... that created a payload section. Then modified the motor mount to take an E-12. Flew great on the E-12 except the delay was too long so I went to a 4 sec delay. Before flying it I had the opportunity and idea of putting in a new Eggtimer Apogee to give a positive deployment at apogee. Fits perfectly in the Payload section right under the nose.

So... off I go flying last week end and NO JOY.... . Flew reasonably well using the redundant 4 second charge on the motor... but 3 separate flights with no Apogee deployment. It preps on the pad ... ready to fire ...cricket chirp... then is still chirping when I recover it. Bench test in vacuum chamber and it works perfectly.... 3 5/32 holes in body tube???? Could the rocket be accelerating too slowly?

Any ideas?
 

Buckeye

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What altitude does this thing achieve? What does your ejection charge wired to the altimeter look like?
 

teepot

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Perhaps the rocket is not getting high enough for the barometric pressure to change. I don't think speed is a factor.
 

Blackbird1936

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What altitude does this thing achieve? What does your ejection charge wired to the altimeter look like?
It is getting around 1000 to 1200 estimated as the altimeter does not start off the pad I have to estimate. Charge is an orange e-bay e match twisted to a lead that is soldered in to the Apogee. The charge is 4x in a plastic straw , sealed each end with hot melt glue. The ignitor in question fired fine in tests prior and post launch though.
 

Buckeye

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Hmm, not sure, then. Might need cerving to chime in.
 

Steve Shannon

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I’m probably misunderstanding what you wrote. You wrote that you have three holes in the body tube for venting, but you also said that the altimeter fits into payload bay right below the nosecone. Is it possible that you have the altimeter in a non-vented section? If so, that would explain its lack of arming.
The altimeter must be in the section of body tube that is ventilated so it can detect atmospheric pressure and thus altitude.
The ejection charges must be in a section where they blow the nosecone off. They shouldn’t pressurize the portion of the body where the altimeter is mounted.
 

Antares JS

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Perhaps the rocket is not getting high enough for the barometric pressure to change. I don't think speed is a factor.
The pressure sensors on these barometers will detect a .0001 atm change. I usually test if the barometer is working by taking a live reading from the altimeter on the floor and on a table. It will sense and show you a .0001-.0002 atm difference.
 

UhClem

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It is getting around 1000 to 1200 estimated as the altimeter does not start off the pad I have to estimate.
A Rocksim simulation using a stock Phoenix file and an E12 shows ~700' so a stretched version will be lower. Will it be lower than the altitude used by the launch detection algorithm?
 
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