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

Joined
Jun 30, 2015
Messages
1,652
Reaction score
1,818
Location
Australia
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!
@don.cannon.wa Are you going to post the pics of your rockets and Av bays? Or just retest with a fresh battery? Before your friends here start throwing punches over the batteries and manufacturers recommendations.....
 

Titan II

Well-Known Member
Joined
Aug 23, 2013
Messages
1,322
Reaction score
454
OP...in case you are bored and want some more conflicting information. One mentions the 400 CS talked about.




 
Last edited:
Joined
Jun 30, 2015
Messages
1,652
Reaction score
1,818
Location
Australia
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
At the time the manual was written it was designed to be used with a 9v Alkaline battery. At that time the construction and peak current delivery capability was different from the current batch and could change again without notice. The brownout capacitor was chosen for that original spec. I'm not sure how it stacks up with todays 9v batteries. It would depend on the chemistry and mechanical recovery time for the newer batteries. My gut says it's probably time to move away from the current generation of 9v batteries because of the construction changes and as fewer people generally use them the availability of fresh stock (which you need in a critical application like rocketry). This makes them a bad choice given the reliability we are expecting and require.
 

Buckeye

Well-Known Member
TRF Supporter
Joined
Sep 5, 2009
Messages
2,993
Reaction score
759
<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>

This is true for electronics originally designed to use LiPos. Missleworks and Perfectflite (most likely the market share leaders) were designed with 9V in mind, and converting to LiPos introduces new issues.

For every LiPo soapbox, there is an equivalent anti-LiPo soapbox:

 
Joined
Feb 26, 2022
Messages
16
Reaction score
6
Location
Edmonds, 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.
Duracell
 

G_T

Well-Known Member
Joined
Dec 29, 2011
Messages
2,670
Reaction score
660
Duracell used to be the 9v battery of choice. That was some years ago now. The construction changed. But for all I know construction may have changed back by now.

IF your cells in whatever battery you use are held to making their electrical connections via compression rather than by soldered or welded connection, then that battery WILL fail at some level of shock and vibe. Then you are relying on the capacitor on the board to (1) fire the charge, causing that shock and vibe, and (2) continuing to power the board afterwards until the battery has presumably restored reliable power supply.

If you cut open one of your batch of Duracell betteries, what is the internal construction? https://en.wikipedia.org/wiki/Nine-volt_battery#/media/File:9V_innards_3_different_cells.jpg https://external-preview.redd.it/cq...bp&s=4da62a97ffcbd597b6dfc360265227d197da6975

Those interested in these batteries may enjoy looking through this article: https://lygte-info.dk/info/BatteryDisassembly9VAlkaline UK.html In particular, note the construction of their example Energizer Alkaline (USA) battery. This is the type of construction I particularly recommend against for rocketry applications. Also look at the Golden Power Heavy Duty Zinc-Carbon (China) battery. Connections made by pressure. So, I would not trust that method of construction either. Ditto a number of others in there. Or ugh, the Philips Extremelife Alkaline. Anyway, read through and look at the pics to get an idea of the range of construction for these cells. Then think about high shock and vibe, and which costruction methods you would trust and which ones you would not.

Note, battery manufacturers do not use one method forever. What used to be a good battery in one batch, might not be a good battery with a different batch. If you are using 9v batteries, I recommend disassembling one from the batch you got and seeing if you like and trust its internal construction.

Hopefully this has been useful information.

Gerald
 

QFactor

L2 - NAR & TRA
Joined
Nov 6, 2019
Messages
374
Reaction score
200
Location
Ohio
This is the current battery construction for a Duracell Procell. The "yellow" case and "gray" case are the same battery - same innards.
All they did was change the case "art work" to the gray design.

170567343_1696827067195201_6842332301671585411_n.jpg 170721971_1696843903860184_8246319476422776588_n.jpg

Have not experienced a failure using them with my RRC2's, RRC3's and Stratologgers.

Have used them with rockets flown on H through M motors - and quite a few AeroTech Warp motors.
 

mtnmanak

Joined
May 5, 2020
Messages
1,555
Reaction score
1,883
As far as batteries go, as has been posted, this is like asking "which epoxy is best?". I use both LiPo's and 9V's in almost every flight. All my Eggtimers are on LiPo's, but I fly all my MissileWorks altimeters on 9Vs. It amazes me during these conversations no one ever mentions 9V Lithiums. They are superior to alkaline 9Vs in every way. They are about 25% lighter than alkaline and they last darn forever.

I have been marking my 9V Lithiums after each flight. This one has 18 flights on an RRC3 and it is still pushing 9.24V:

PXL_20220501_180802888.jpg

Sure, those Energizer Lithiums are about twice as expensive as the alkaline batteries, but the one pictured above has lasted me for 2 years and is still going. I plan to fly it next weekend. I would love to get 30+ flights out of it.

Sorry about that. I posted pictures on other threads. View attachment 516628

It is difficult to diagnose much from that picture. Since this altimeter works fine in another rocket and it is recording flight data, I would suspect it is shorting out somewhere in this rocket.
 
Last edited:

QFactor

L2 - NAR & TRA
Joined
Nov 6, 2019
Messages
374
Reaction score
200
Location
Ohio
I use that tick-mark method too on my 9-volt batteries. Can't trust my memory anymore.
 
Joined
Jun 30, 2015
Messages
1,652
Reaction score
1,818
Location
Australia
This is true for electronics originally designed to use LiPos. Missleworks and Perfectflite (most likely the market share leaders) were designed with 9V in mind, and converting to LiPos introduces new issues.

For every LiPo soapbox, there is an equivalent anti-LiPo soapbox:

Converting to a LiPo may cause an issue with some older altimeter designs. Any competent designer should have current limiting incorporated. Chris does.
The main problem I see is that design changes have been made to batteries that still have the same designation. A Duracell 9v MN1604 is still being sold as a MN1604 although the current limit is half what it was with the older AAA construction and the pressure connection method could cause issues. So by using an off the shelf disposable battery, you really don't know what you have as an energy source unless you buy 2 and disassemble one...... That's not an ideal situation and what do you do if you discover the construction has changed.
Norm
 
Joined
Feb 26, 2022
Messages
16
Reaction score
6
Location
Edmonds, WA
This is the current battery construction for a Duracell Procell. The "yellow" case and "gray" case are the same battery - same innards.
All they did was change the case "art work" to the gray design.

View attachment 516650 View attachment 516651

Have not experienced a failure using them with my RRC2's, RRC3's and Stratologgers.

Have used them with rockets flown on H through M motors - and quite a few AeroTech Warp motors.
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.
Thanks for your advice. I'll launch Tuesday morning with my lithium battery and see if anything improves.
 
Top