DD Woes. The Tragic StratoLogger Event.

[Kruegon]

Today was the launch for Birmingham Rocket Boys, NAR Section 665. The wind was bad. Very little launching occurred.

The wind died to a low roar and I got brave. Estes Scion on an AT G75J. This rocket was launched two weeks ago at SEARS. Two flights. Both successful. At apogee, the rocket rolled over and started down. Went quite a significant ways down. And finally the altimeter fired. Except if fired both charges. Main popped at about 1400' and wind drift took it into a tree roughly 40' up.

The altimeter is making a vey odd locator sound. Normally it has a siren sound. Right now it sounds a fair bit like crickets.

I'm going back tomorrow to cut the tree down (yes I have permission), to recover the motor, altimeter, laundry and hopefully the entire rocket.

Has anyone ever experienced this on a StratoLogger before?

 

[tim cubbedge]

How bad was the wind? Mine makes the warble for a minute or so then goes thru the flight sequence (altitude,speed) then warbles again & repeats cycle till I turn it off.

 

[Kruegon]

Wind was about 12-15mph.

Mine does the same. But this time it's not worbling, it sounds like crickets. I'll know more after I recover it. But I'm worried it's shot. This is only the 6th or 7th flight on that altimeter.

 

[tim cubbedge]

Don't think it had anything to do with winds. I launched 2 rockets today with perfect flite altimeters & 15 mph winds. Both flights deployed as scheduled. Might contact Perfect Flite if you get it back. Good customer service on repairs.

 

[Kruegon]

Oh I'll get it back. Man vs tree. Man WILL win. It's more the depressing flight than anything. It was about as perfect as possible on the way up. The G75 was nice and smokey with a clean tower release and only moderate weather cocking. I haven't even painted her yet. Next project is a 29mm MMT, DD, 6'4", 1.6" Mean Machine.

 

[crazyed]

I have a" missile works "alt. It started making a sound similar to what you described. The "buzzer' was contaminated with blow by from the deploy charges. I cleaned it out softly with alcohol and a swab. No more crickets. If you have electronic parts cleaner..it might be a better choice . If the alt uses a barometric sensor, those tiny ports may somehow but a little dirty as well.
Good luck with the mean machine DD... post pics :grin:

 

[mpitfield]

Are you talking SLCF or SL100? How big is the AV bay, how many sampling holes do you have and what size are they?

 

[Kruegon]

6" bay in a 3" tube. One sampling port 5/32 diam. StratoLoggerCF.

 

[mpitfield]

6" bay in a 3" tube. One sampling port 5/32 diam. StratoLoggerCF.

I would personally do 3 x 1/16th for that size AV bay. There are several threads on the reasoning to using a minimum of 3 holes. I typically use the same number of holes as fins, which so far is just 3 or 4. Regardless of the condition of the altimeter, not having the correct sampling vent can effectively delay the apogee event.

BTW is this the first time you are using the CF. The SLCF does have a slightly different tone out of the box than the SL100 and you can also vary the pitch. Also it goes through a routine post flight, beeps out the altitude, can't recall if it does this once or multiple time but eventually I believe it has a siren (could be getting it mixed up with the SL100) then the it goes silent and then it starts it all over again.

 

[Kruegon]

Well the current size of the sampling port is larger than the specified size for a single port. Requirement of the pull pin. This is the 6th or 7th flight of this altimeter. And the only one I have ever owned. The sound is different than it's ever been before. The difference in sound and the double deployment worry me.

The drogue was very late and the main was way too early. And they blew at the same time. I'm leaving to retrieve it shortly. I'll hopefully have more info soon.

 

[TimeBandit]

What type of battery are you using?
If it was a 9V was it still good?
If it was a LiPo, the StratoLogger requires a minimum of 4v, was it at least a 2 cell 7.4v LiPo fully charged?

 

[mpitfield]

Well the current size of the sampling port is larger than the specified size for a single port. Requirement of the pull pin. This is the 6th or 7th flight of this altimeter. And the only one I have ever owned. The sound is different than it's ever been before. The difference in sound and the double deployment worry me.

The drogue was very late and the main was way too early. And they blew at the same time. I'm leaving to retrieve it shortly. I'll hopefully have more info soon.

Not to dismiss the sound and double deployment as you may well have a hardware issue there, however on the topic of the sampling holes size there is a thread, actually it has come up in a few threads, where some pretty smart people on this topic discussed issues with a single altimeter sampling hole. I wish I could provide you the links but my high level somewhat ignorant interpretation on the topic is that with one sampling hole you could internal pressures or turbulence or something to that effect which could have an effect on the sampling. Honestly I read the threads and at the time it made sense to me so I adopted it as a practice, but to regurgitate it technically is beyond me. I believe Bob Krech and Chris Erving contributed to as posters to the thread.

BTW have you run the internal diagnostics on the altimeter? I would also reach out to PerfectFlight and see what they have to add.

 

[Kruegon]

It was a 9v battery. Rayovac Pro. Better life than regular Energizer or Duracell. Still good. Still has the siren on the SL going today.

I went to cut the tree down. Success! Tree fell the wrong direction. Failure!

I'll go back and try again in a day or two.

 

[Buckeye]

It was a 9v battery. Rayovac Pro. Better life than regular Energizer or Duracell. Still good. Still has the siren on the SL going today.

I went to cut the tree down. Success! Tree fell the wrong direction. Failure!

I'll go back and try again in a day or two.

What was the tree cutting failure, and why are you going back?

 

[mpitfield]

I went to cut the tree down. Success! Tree fell the wrong direction. Failure!

I'll go back and try again in a day or two.

I would be interested in seeing the altimeter data in it's raw format once the tree gives it up, also if the altimeter is still making the noise can you grab an audio or audio/video and throw it up on YouTube.

 

[Kruegon]

The tree fell the wrong direction. It had a slight lean one direction, but I needed it to fall the other direction. My chainsaw is non functional right now. I had to take the axe to it.

I chopped very cleanly from the side I needed it to fall towards. Stupidly strong tree. Had to chop over 3/4 of the way through before it even began to lean. Finally it started to move. And just as it began to lean the proper direction, a very nice gust of wind caught the top and shoved it the wrong way.

Now it's laying across the branches of 2 or 3 other trees. I'll drop the other trees as soon as I have a chain saw. The big problem now it that the rocket is on the downward side of the limbs.

 

[Kruegon]

Heading out shortly to attempt another recovery of the lost rocket. New tools and ideas on how to get it down. Hopefully I can upload the flight data to here this afternoon.

 

[Kruegon]

Scion has been recovered. Only the slightest damage to the booster section. Easy fix. I'll be downloading the StratoLoggerCF data shortly. I'll post it here for views and comments.

 

[Kruegon]

Well, the data was recovered. As far as I can tell, there is nothing wrong with the altimeter. New battery (after a week, the old battery was drained) and fired up like normal. Sounds are even normal. Unfortunately, I can't get the location siren to activate without a flight to see if it's normal again. There is no damage of any kind to the A/V Bay.

So let's recap the scenario. Nominal launch and flight on an AT G75J. Drogueless at Apogee, Main at 200'. Launch went off like a charm. Beautiful flight, slight weather cocking from moderate winds of about 15MPH. Visual delay of drogue deployment. Rocket was slightly ballistic before the altimeter deployed the charge. Both charges deployed simultaneously. The report was EXTREMELY loud. Both charges were 0.7g FFFFg powder. The rocket is very securely friction fitted at body joint and nose cone. Both separated simultaneously during the deployment charge. This was visible from it's altitude. The rocket drifted east for several hundred yards to a tree. There was no audible report during the decent.

As you will see, the log shows the altimeter firing both deployment charges at their respective times. I inspected the wiring inside the A/V Bay before disconnecting the altimeter for data retrieval. Everything was in perfect order. If anyone can find an issue in the data, please share it.


The upload is not working again. Try this link.

10/17/15 Estes Scion StratoLoggerCF Flight Data

Thanks for any and all help you can Provide.

 

[tim cubbedge]

You sure the main deployed the same time as drogue or could it have been a second or so later? How long is your drogue shock cord? I've had my main deploy at apogee due to too short of a drogue shock cord with a friction fit NC.

 

[rharshberger]

A loud report from the ejection charge is a sign of a well contained BP charge. If its confined very tightly it will go bang rather loudly.

 

[Kruegon]

You sure the main deployed the same time as drogue or could it have been a second or so later? How long is your drogue shock cord? I've had my main deploy at apogee due to too short of a drogue shock cord with a friction fit NC.

A loud report from the ejection charge is a sign of a well contained BP charge. If its confined very tightly it will go bang rather loudly.

Positive. The nose cone ejected very clearly and actually went farther from the upper tube than the booster did. The parachute began deploying before the lower shock cord even pulled tight. Drogue shock cord is 10' and the main shock cord is 15'. This same rocket has flown twice previously, with the same ejection charges, in the same configuration. This deployment was extremely loud. Both my president and vice president of the club are L2 certified. They both said it was way too loud for a 0.7g charge. They both witnessed the deployment with me. We have no doubt that they both deployed simultaneously. The question is why. According to the data, the altimeter clearly shows functioning and activating both charges separately at the appropriate time. Since there was no audible report after the initial report, we know the second charge did not blow at 200'. But both charges clearly blew. I have the spent e-matches to prove it. It's definitely a conundrum. I also checked closely to ensure that no stray strand of wire was able to cross connect to the parallel charge. All wiring was contained properly in their designated terminal blocks. This was the 6th flight on this altimeter. My biggest concern now is, should I trust this altimeter again? or, should I contact PerfectFlite regarding the issue and as for it to be warrantied?

 

[tim cubbedge]

Id send it back then. Contact him first. He's pretty good about testing and repairs. He's brought 2 of mine back to life after encounters in water.

FYI....just a word of advice, your drogue should probably be longer than your main. At least that's what most folk around here will tell you.

 

[Kruegon]

Well my drogue is actually drogueless. And my charges are not strong enough to actually blow the sections to full extension. I "Z" my shock cords. Often they come back still having two or three folds in the tape. Since the parachute does actually stress the body when the nose cone stops by the body doesn't, I have it a few feet extra. The club president even commented that it was "an awful lot of shock cord" for this rocket.

 

[mpitfield]

I looked at your data. I converted it to an Excel file, which for some reason I cannot upload even with .csv, .xls, or .xlsx. Regardless it almost looks like you were hitting some thermals as the decent rate seems to settle then slow down then speed up quite a few times. One thing I would also agree with is that the apogee event did fire and so did the main and nothing in between. You can clearly see a voltage drop @ 9.25 seconds into the flight (apogee) then again @ 90.4 seconds (main), very typical of a 9V alkaline battery, which in this case helps with the diagnostics.

If you want the file I created I can email it to you if you PM me with your email address.

Beyond what is obviously shown in the logs I am not sure you are going to get more out of them.

 

[Kruegon]

I've sent an email to PerfectFlite. I attached the log file and explained the entire flight as well as all details found post recovery. Hopefully he can provide better information and a way to ensure the issue is resolved.

 

[KenECoyote]

Out of curiosity, how many and how big are the sampling holes? If you only have two and there is gusting winds, I'd think that can screw around with altimeters and give odd readings.

 

[Kruegon]

The sampling holes were suppose to be extremely small if I did 3. Like around 1/16" for 3. For a single hole is was suppose to be a little under 1/8". I ended up doing 1 hole at 5/32 as that was the size needed for the switch pin in the A/V bay.

 

[bobkrech]

I have a different interpretation of what happened during your flight based on what you observed during your flight coupled to your altimeter data.

1.) The altimeter operation was normal. The altimeter data indicated the StratoLogger fired the apogee charge circuit at apogee and fired the main charge circuit at 200' agl.

2.) Analysis of the altimeter data indicates the main deployed either at or near apogee and the rocket descended on the main at ~14 fps until id landed at a location about 20' higher than the launch altitude.

3.) You said you observed the rocket weather-cocked slightly on ascent. While the altimeter can not confirm this, it is logical to assume this would happen in a 15 mph wind.

4.) The apogee deployment charge fired at apogee, not slightly after apogee as you assumed. This is confirmed by the altimeter data. Because the rocket weather-cocked, it may have looked like the deployment was slightly ballistic, but this is not borne out by the data. Because of the weather-cocking, the rocket has horizontal velocity at apogee so it would appear to the observer on the ground that it went over apogee and then deployed but this is an optical illusion.

5.) You comments about the loudness of the ejection charge is not unexpected. Since the rocket weather-cocked, the rocket was upwind when the deployment occurred so the sound was blown towards you and the acoustic wave transit time was shorter than a no-wind apogee.

6.) I believe your nose cone was loosely fitted and the initial pyroshock moved the nosecone out and the shock cord jerk popped it off. Over the next 4 seconds, the parachute was pulled out due to the drag of the nose cone and then deployed. The would also lend to the illusion of the over the top deployment. My evidence for this possible delayed main deployment is the little s-bend in the altitude at ~15 second, about 4-5 seconds after apogee.

7.) I believe the main charge fired at 200' but you did not hear it. In a 15 mph wind, you rocket drifted 1760' downwind from apogee during the 80 seconds it took to get down to 200'. A 0.7 gram charge going off at that distance downwind and that low an altitude will not be heard.

This scenario matches your observations and the altimeter data so I believe it is what occurred.

Bob

 

[Kruegon]

Except for one thing. The rocket weather cocked away from us and drifted back to us. When it reached approx 200', it was less than 25 yds away from us. So distance 75", elevation 200". Well within distance to hear a report.