Is there a range of airframe diameters within which an RRC3 not work?

[don.cannon.wa]

As I begin to learn how to use RRC3 altimeters I have prepared a test workhorse that provides a means for me to do a lot of inexpensive testing. That is in the form of an Estes Cherokee-E that is customized into an 8” booster, an 8” ebay, an 8” payload section, a hollowed out nose cone, and a steady supply of E12-6 engines. A fact having nothing to do with this question, but that I thought amusing is, due to the modifications, this relatively light performance rocket has been reduced to an air pig with a thrust/weight ratio of 4.3.
I have shot this up 6 times with the main chute channel set to fire at 500 feet altitude, and the problem I’m seeing is, the channel has never fired. The altimeter provides data, like max altitude – always well over the 300’ arming altitude and the 500’ ejection setting – and descent rate, but does not fire. Between the 5th and 6th flights, this last Sunday at a UROC event, I used the same altimeter in my 3” SBR Thor, configured identically. It worked exactly as I would expect. I have varied the vent holes in the ebay as the failures mounted – four 1/16” and then ⅛”. There is ample space between the altimeter and the sled on which it’s mounted – exactly the same as was in the Thor. The 9V battery has been consistently in the area of 8.5 v, and the continuity and set mode suggest the wiring is right for the main channel to fire.
Because it’s clear the altimeter works in the Thor, I’m left wondering why not in the Cherokee? And, if never in the Cherokee, can the RRC3 even technically work in a BT55 body tube? That is important, because I have a 38mm Blackhawk under construction, and with the BT55 being essentially a 34mm, I’m concerned about whether or not the RRC3 will even work in a tube as narrow as the 38mm. It’s one thing for it to fail when I’m trying to get it working alongside a motor-ejected drogue chute on the Cherokee, but will be very different when the Blackhawk will be exclusively altimeter ejected. I’d like to figure this out before ever placing the Blackhawk on the pad.
Anybody have any knowledge about effective tube diameters for the RRC3 or a suggestion for getting the Cherokee to fire? Thanks!

 

[rharshberger]

As I begin to learn how to use RRC3 altimeters I have prepared a test workhorse that provides a means for me to do a lot of inexpensive testing. That is in the form of an Estes Cherokee-E that is customized into an 8” booster, an 8” ebay, an 8” payload section, a hollowed out nose cone, and a steady supply of E12-6 engines. A fact having nothing to do with this question, but that I thought amusing is, due to the modifications, this relatively light performance rocket has been reduced to an air pig with a thrust/weight ratio of 4.3.
I have shot this up 6 times with the main chute channel set to fire at 500 feet altitude, and the problem I’m seeing is, the channel has never fired. The altimeter provides data, like max altitude – always well over the 300’ arming altitude and the 500’ ejection setting – and descent rate, but does not fire. Between the 5th and 6th flights, this last Sunday at a UROC event, I used the same altimeter in my 3” SBR Thor, configured identically. It worked exactly as I would expect. I have varied the vent holes in the ebay as the failures mounted – four 1/16” and then ⅛”. There is ample space between the altimeter and the sled on which it’s mounted – exactly the same as was in the Thor. The 9V battery has been consistently in the area of 8.5 v, and the continuity and set mode suggest the wiring is right for the main channel to fire.
Because it’s clear the altimeter works in the Thor, I’m left wondering why not in the Cherokee? And, if never in the Cherokee, can the RRC3 even technically work in a BT55 body tube? That is important, because I have a 38mm Blackhawk under construction, and with the BT55 being essentially a 34mm, I’m concerned about whether or not the RRC3 will even work in a tube as narrow as the 38mm. It’s one thing for it to fail when I’m trying to get it working alongside a motor-ejected drogue chute on the Cherokee, but will be very different when the Blackhawk will be exclusively altimeter ejected. I’d like to figure this out before ever placing the Blackhawk on the pad.
Anybody have any knowledge about effective tube diameters for the RRC3 or a suggestion for getting the Cherokee to fire? Thanks!

Properly setup the RRC3 should work in any size airframe it fits in, not sure what issue is causing the failure you are experiencing. I have flown mine in 38mm and up airframes, for smalller I usually use Eggtimer Quarks.

 

[StreuB1]

Here is my AV bay and sled layout for my Madcow Nike-Apache, Apache sustainer. It is a 1.5" FG airframe and the inside diameter of the AV bay tube is just under 1 3/8".

Bare in mine, this is controlling dual deploy plus sustainer ignition so lots going on. It all fits.....but its tricky getting all the e-match wires to play nice and get it all closed up.

 

[StreuB1]

For reference. The threaded rods that I use for the sled are #4-40 and those tubes are thin wall aluminum hobby tubing. Sled base and battery footing are 1/32" G10 plate, all bonded with JB weld after being thoroughly roughed up and prepped.

 

[OzHybrid]

Post lots of pics showing the sled, relationship between position of RRC3 and holes, Whole rocket and transitions, And the one that works...

 

[user 30299]

As I begin to learn how to use RRC3 altimeters I have prepared a test workhorse that provides a means for me to do a lot of inexpensive testing. That is in the form of an Estes Cherokee-E that is customized into an 8” booster, an 8” ebay, an 8” payload section, a hollowed out nose cone, and a steady supply of E12-6 engines. A fact having nothing to do with this question, but that I thought amusing is, due to the modifications, this relatively light performance rocket has been reduced to an air pig with a thrust/weight ratio of 4.3.
I have shot this up 6 times with the main chute channel set to fire at 500 feet altitude, and the problem I’m seeing is, the channel has never fired. The altimeter provides data, like max altitude – always well over the 300’ arming altitude and the 500’ ejection setting – and descent rate, but does not fire. Between the 5th and 6th flights, this last Sunday at a UROC event, I used the same altimeter in my 3” SBR Thor, configured identically. It worked exactly as I would expect. I have varied the vent holes in the ebay as the failures mounted – four 1/16” and then ⅛”. There is ample space between the altimeter and the sled on which it’s mounted – exactly the same as was in the Thor. The 9V battery has been consistently in the area of 8.5 v, and the continuity and set mode suggest the wiring is right for the main channel to fire.
Because it’s clear the altimeter works in the Thor, I’m left wondering why not in the Cherokee? And, if never in the Cherokee, can the RRC3 even technically work in a BT55 body tube? That is important, because I have a 38mm Blackhawk under construction, and with the BT55 being essentially a 34mm, I’m concerned about whether or not the RRC3 will even work in a tube as narrow as the 38mm. It’s one thing for it to fail when I’m trying to get it working alongside a motor-ejected drogue chute on the Cherokee, but will be very different when the Blackhawk will be exclusively altimeter ejected. I’d like to figure this out before ever placing the Blackhawk on the pad.
Anybody have any knowledge about effective tube diameters for the RRC3 or a suggestion for getting the Cherokee to fire? Thanks!

Can you post a picture of your setup (sled) for the Cherokee-E? And are you using the same sled in the Thor, or are you taking the RRC3 off the Cherokee's sled and then mounting it on the Thor's sled?

 

[Titan II]

The RRC3s work fine. I have one in a 38 Blackhawk and one in a 38mm Apache. No problems.

 

[G_T]

9v batteries have had some construction changes in recent years, to a double stack of small round cells. They are more succeptible to acceleration related issues. That could be your problem.

If you still have some of that brand and batch of batteries on hand, peel one open and see how it is constructed. If it is just a stack of small cells held together by mild compression rather than soldered or welded wires, that may well be your problem. Such batteries are not useful for rocketry applications.

Not all brands that used to be good, are still good.

Gerald

PS - Additionally, if your battery cannot source enough current firing a charge, without dropping too much voltage, attempting to do so can reboot the board. I had that happen to me a couple flights years back before I figured it out. The other board didn't have that happen so all the flights were successful. Redundancy to the rescue! Anyway some lithium cells have a little circuit chip in the wrap which shuts off the battery under high current draw, to prevent a fire. Bad plan to use such cells for an altimeter. Not all battery types and brands, and even batches, are equal for our applications.

 

[cerving]

<soapbox>Get Lipo's and rid of the 9V batteries... they're big, heavy, don't source much current, and they actually end up costing more if you use them a few times and switch them out. This is especially true for 38mm rockets... you're adding a ton of weight, and they're huge compared to say a 300 mAH 2S Lipo.</soapbox>

 

[OzHybrid]

Here is my AV bay and sled layout for my Madcow Nike-Apache, Apache sustainer. It is a 1.5" FG airframe and the inside diameter of the AV bay tube is just under 1 3/8".

Bare in mine, this is controlling dual deploy plus sustainer ignition so lots going on. It all fits.....but its tricky getting all the e-match wires to play nice and get it all closed up.

View attachment 516361

View attachment 516362

View attachment 516363

Which brand 9v battery are you using?

 

[StreuB1]

Which brand 9v battery are you using?

Rayovac High Energy.

I just took one apart last night and it is the new design with the stacked cells in lieu of the original 6xAAAA cells in series. They work fine for e-matches though, never had an issue. Did a short circuit current test on one earlier today and got 2.2amps which is plenty for single matches.

Though......just recently learning of the redesign of modern 9V batteries and that they exhibit half the short circuit current as the legacy design and the comments of people like Cris (above). This all makes me think about switching to LiPo.....I just worry about current as I mostly use MissileWorks which are designed for use with 9V batteries and as such, their MOSFET is limited to current values that are lower than what a 2S 30C LiPo can sink during short circuit. I know some use a current limiting resistor when they use LiPo's but.....its another link in the chain.

Cris, I would like to hear your thoughts on my comments above, please.

BTW, I need to get an order over to you for for a Finder Mini, BT add-on for my tracker LCD, antenna for my current Finder and the USB base station dongle since I bend the wire whip, and the voice unit for my Finder LCD.

 

[Conway Stevens]

<soapbox>Get Lipo's and rid of the 9V batteries... they're big, heavy, don't source much current, and they actually end up costing more if you use them a few times and switch them out. This is especially true for 38mm rockets... you're adding a ton of weight, and they're huge compared to say a 300 mAH 2S Lipo.</soapbox>

For the RRc3 or the RRC2L or any of the current Missleworks. They will work perfectly on a 1s 150 mah and larger 1s. Really no need bigger then a 1s 400mah. You can save weight by huge amounts and have a much better battery then a 9v

 

[Hobie1dog]

Look at this battery "State of Charge" chart and the percentage of charge in the battery. a 12 volt battery that measures 12 volts on a digital meter only has 45% of its charge left. Same thing with the 6 volt chart readings. An 8V battery at 7.5 Volts has only 10% of its charge.So if your 9 volt is measuring 8.5 volts then it only has >20% of its charge left. "According to the Energizer Battery Application Manual, a new 1.5V cell typically has an open circuit voltage of 1.58V. A nine volt battery has six cells, so a new would have an open circuit voltage of 9.48V. A reading of 9V indicates a battery with no to less than 10% discharge"
Go measure a brand new 9 volt battery with a digital meter. Remember the one guy on here found out Duracell batteries are having big time problems now. I wouldn't be using a battery that reads that low.

 

[OzHybrid]

I think we're all agreed that the battery choice is bad and needs to be eliminated as an error source. Either due to voltage or increased g in the smaller dia causing issues with the newer battery- pressure stacked assembly.

 

[OzHybrid]

Look at this battery "State of Charge" chart and the percentage of charge in the battery. a 12 volt battery that measures 12 volts on a digital meter only has 45% of its charge left. Same thing with the 6 volt chart readings. An 8V battery at 7.5 Volts has only 10% of its charge.So if your 9 volt is measuring 8.5 volts then it only has >20% of its charge left. "According to the Energizer Battery Application Manual, a new 1.5V cell typically has an open circuit voltage of 1.58V. A nine volt battery has six cells, so a new would have an open circuit voltage of 9.48V. A reading of 9V indicates a battery with no to less than 10% discharge"
Go measure a brand new 9 volt battery with a digital meter. Remember the one guy on here found out Duracell batteries are having big time problems now. I wouldn't be using a battery that reads that low.

Those figures are for a lead acid chemistry. The alkaline discharge graph is even steeper. However having re read the original post, he made 2 successful tests on the same battery in a larger airframe later in the day.
So issue could be G force related on battery construction or clip or something else. But battery type should be changed to eliminate it as an issue..

 

[user 30299]

For the RRc3 or the RRC2L or any of the current Missleworks. They will work perfectly on a 1s 150 mah and larger 1s. Really no need bigger then a 1s 400mah. You can save weight by huge amounts and have a much better battery then a 9v

What's the weight difference?

 

[OzHybrid]

a 110 mAh 3.7v lithium is 2.2g. A MN1604 is 45g plus snap connector.

 

[Conway Stevens]

What's the weight difference?

As mentioned above the weight difference is usually around 2 to 3 grams for the lipo vs 40 grams or so for the 9v.

 

[StreuB1]

I purchased (2) 2S 300mah 35C LiPo's to play around with, should be here today.

Pricey little buggers but then again, so is buying lots of 9V's.

 

[Conway Stevens]

I purchased (2) 2S 300mah 35C LiPo's to play around with, should be here today.

Pricey little buggers but then again, so is buying lots of 9V's.

With a 2s 300mah you can power a Eggtimer wifi switch and the altimeter. Most altimeters if not using a wifi switch will have more then enough power with a 1s 200 to 400 mah battery.

 

[StreuB1]

With a 2s 300mah you can power a Eggtimer wifi switch and the altimeter. Most altimeters if not using a wifi switch will have more then enough power with a 1s 200 to 400 mah battery.

I predominantly have MissileWorks but also have 2 Ravens and an EggFinder GPS. The EggFinder uses a 2S 400mah pack and the rest all use 9V. We will see how these 300mah packs fit and work as I could see myself transitioning over to these.

 

[don.cannon.wa]

Here is my AV bay and sled layout for my Madcow Nike-Apache, Apache sustainer. It is a 1.5" FG airframe and the inside diameter of the AV bay tube is just under 1 3/8".

Bare in mine, this is controlling dual deploy plus sustainer ignition so lots going on. It all fits.....but its tricky getting all the e-match wires to play nice and get it all closed up.

View attachment 516361

View attachment 516362

View attachment 516363

That's a fine looking unit -- and obviously with a similar diameter to my own. Here are a couple of pictures of my admittedly inferior version, which was made only for testing the altimeter's function so my fit and finish is not up to your level.

9v batteries have had some construction changes in recent years, to a double stack of small round cells. They are more succeptible to acceleration related issues. That could be your problem.

If you still have some of that brand and batch of batteries on hand, peel one open and see how it is constructed. If it is just a stack of small cells held together by mild compression rather than soldered or welded wires, that may well be your problem. Such batteries are not useful for rocketry applications.

Not all brands that used to be good, are still good.

Gerald

PS - Additionally, if your battery cannot source enough current firing a charge, without dropping too much voltage, attempting to do so can reboot the board. I had that happen to me a couple flights years back before I figured it out. The other board didn't have that happen so all the flights were successful. Redundancy to the rescue! Anyway some lithium cells have a little circuit chip in the wrap which shuts off the battery under high current draw, to prevent a fire. Bad plan to use such cells for an altimeter. Not all battery types and brands, and even batches, are equal for our applications.

Gerald, Thanks for your response. I used the same Duracell battery last Sunday down in Utah in my 3" Thor that I used on Thursday on the BT-55 Cherokee. The battery was new on Sunday, I recovered the rocket and shut off the altimeter within 15 minutes of turning it on and have not used it since. It had the amperage necessary new, so maybe it fizzled out between the initial arming and reading of the flight data. Perhaps I can try again with a new or better battery.

 

[don.cannon.wa]

Rayovac High Energy.

I just took one apart last night and it is the new design with the stacked cells in lieu of the original 6xAAAA cells in series. They work fine for e-matches though, never had an issue. Did a short circuit current test on one earlier today and got 2.2amps which is plenty for single matches.

Though......just recently learning of the redesign of modern 9V batteries and that they exhibit half the short circuit current as the legacy design and the comments of people like Cris (above). This all makes me think about switching to LiPo.....I just worry about current as I mostly use MissileWorks which are designed for use with 9V batteries and as such, their MOSFET is limited to current values that are lower than what a 2S 30C LiPo can sink during short circuit. I know some use a current limiting resistor when they use LiPo's but.....its another link in the chain.

Cris, I would like to hear your thoughts on my comments above, please.

BTW, I need to get an order over to you for for a Finder Mini, BT add-on for my tracker LCD, antenna for my current Finder and the USB base station dongle since I bend the wire whip, and the voice unit for my Finder LCD.

Good ideas there. I have a Lithium battery that I've not used for this. I think, even though the same Duracell worked on Sunday that did not work on Thursday, I'll give the smaller, more powerful Lithium cell a try. Thanks!

 

[don.cannon.wa]

Those figures are for a lead acid chemistry. The alkaline discharge graph is even steeper. However having re read the original post, he made 2 successful tests on the same battery in a larger airframe later in the day.
So issue could be G force related on battery construction or clip or something else. But battery type should be changed to eliminate it as an issue..

I'm on the battery change. Next up, Li rechargeable that's been collecting dust in my toolbox.

 

[Conway Stevens]

I predominantly have MissileWorks but also have 2 Ravens and an EggFinder GPS. The EggFinder uses a 2S 400mah pack and the rest all use 9V. We will see how these 300mah packs fit and work as I could see myself transitioning over to these.

If you look at what Missleworks and Featherweight both recommend for batteries for use with their altimeters they really recommend a 1s. Even their tracking equipment are 1s. The Eggfinder stuff ive found is more tuned to using 2s as power needs are different. Alot of the 2s have enough current output that should a altimeter output get shorted it will fry the altimeter. But. If your using a wifi switch to run one of those altimeters youd have to use a 2s 300mah minimum as the wifi switch needs it.

 

[Titan II]

If you look at what Missleworks and Featherweight both recommend for batteries for use with their altimeters they really recommend a 1s.

Seriously? This is a far cry from "they really recommend a 1s." If there is something else from MW to support your statement, may I have a citation?

From the RRC3 quick start guide:

The RRC3 is designed to be powered by a standard 9‐volt alkaline. You can use any battery in the 3.7 ‐ 10 volt range, but there are other considerations when using these alternate battery types.

From the RRC3 manual:

The RRC3 is designed to be operated with a standard 9‐volt alkaline battery. Standard 9V alkalines are an optimal choice, providing an inexpensive and widely available battery type with secure snap connectors. Always purchase and use premium alkaline batteries. Other battery types can be used, including NiCd, NiMH, LiPo, or other battery chemistries. Your battery choice must source and maintain an absolute minimum of 3.5 volts, and also be limited to a maximum of 10 volts.

From the RRC2+ manual:

The RRC2+ is designed to be powered by a standard 9-volt alkaline battery. You can use any battery within 3.7V to 10V, but there are other considerations when using these alternate battery types.


On another note. I have been using MW for 13 years and have maybe a dozen or so. If weight and size are not an issue, I use a 9V. Otherwise, I typically use a 120 or 180 2s LiPo. They all work well. This is my 38mm Nike-Apache bay:

 

[StreuB1]

A 1S could brownout the unit, even with the capacitor. A 1S is literally at the low voltage threshold of the MW architecture. A 2S on the other hand is right at the sweet spot that the MW is designed to operate.

 

[Conway Stevens]

Seriously? This is a far cry from "they really recommend a 1s." If there is something else from MW to support your statement, may I have a citation?

From the RRC3 quick start guide:

The RRC3 is designed to be powered by a standard 9‐volt alkaline. You can use any battery in the 3.7 ‐ 10 volt range, but there are other considerations when using these alternate battery types.

From the RRC3 manual:

The RRC3 is designed to be operated with a standard 9‐volt alkaline battery. Standard 9V alkalines are an optimal choice, providing an inexpensive and widely available battery type with secure snap connectors. Always purchase and use premium alkaline batteries. Other battery types can be used, including NiCd, NiMH, LiPo, or other battery chemistries. Your battery choice must source and maintain an absolute minimum of 3.5 volts, and also be limited to a maximum of 10 volts.

From the RRC2+ manual:

The RRC2+ is designed to be powered by a standard 9-volt alkaline battery. You can use any battery within 3.7V to 10V, but there are other considerations when using these alternate battery types.

Its not about voltage. Its about curent the 2s batteries are able to deliver crazy amounts more of current vs a 1s. There are posts actually here on TRF where Jim Amos, owner of Missleworks states this could be an issue. The outputs have a 5 amp rated output. 9v batteries do not exceed that. The Strataloger by perfect flight and the Featherweight Raven 4 also have these same concens. Im looking for the discussion that occured years ogo where Jim Amos actually talked about this and his high recommendation was the sparkfun 1s 400mah battery. In fact on their website for a battery recommendation they have a link to it. I will email Jim and post his response if i cant find the discussion. Here is a post in another discussion from Adrian that owns Featherweight altimeters aka Raven4 and he basically states the same issue possible. Can you use a 2s. Sure ive done it. Is it what the manufacturer recommends.. no.

 

[Conway Stevens]

A 1S could brownout the unit, even with the capacitor. A 1S is literally at the low voltage threshold of the MW architecture. A 2S on the other hand is right at the sweet spot that the MW is designed to operate.

It wont brownout. They use a capacitior to prevent this from occuring let alone the power regulation in the systemis designed for the lower voltage. Again. Its not a voltage issue. Its a current issue. Ive used 1s 400mah batteries on Missleworks altimeters fora long time now. Missleworks was actually local to me for 20 years, ive personally flown Jims altimeters since they were first introduced into rocketry in the late 90s early 2000s. The 2s batteries will deliver higher current output then the 5 amp output limits are able to handle. It can fry an output. Will it... not always. Can it. Yes. Especially if the match shorts when it fires.

 

[don.cannon.wa]

Seriously? This is a far cry from "they really recommend a 1s." If there is something else from MW to support your statement, may I have a citation?

From the RRC3 quick start guide:

The RRC3 is designed to be powered by a standard 9‐volt alkaline. You can use any battery in the 3.7 ‐ 10 volt range, but there are other considerations when using these alternate battery types.

From the RRC3 manual:

The RRC3 is designed to be operated with a standard 9‐volt alkaline battery. Standard 9V alkalines are an optimal choice, providing an inexpensive and widely available battery type with secure snap connectors. Always purchase and use premium alkaline batteries. Other battery types can be used, including NiCd, NiMH, LiPo, or other battery chemistries. Your battery choice must source and maintain an absolute minimum of 3.5 volts, and also be limited to a maximum of 10 volts.

From the RRC2+ manual:

The RRC2+ is designed to be powered by a standard 9-volt alkaline battery. You can use any battery within 3.7V to 10V, but there are other considerations when using these alternate battery types.


On another note. I have been using MW for 13 years and have maybe a dozen or so. If weight and size are not an issue, I use a 9V. Otherwise, I typically use a 120 or 180 2s LiPo. They all work well. This is my 38mm Nike-Apache bay:

View attachment 516570

Nice! Okay, it's probably not the battery.