A Very Boosted Bertha

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WillMarchant

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I was able to fly a Boosted Bertha with 24mm 1st stage with a C11-0 to A8-5 combo yesterday. The liftoff is *much* improved over the stock B6-0 or C6-0 first stage.

The conversion is pretty straightforward. You need a Boosted Bertha kit and:
Estes 3159 motor mount kit
Estes 9751 motor retainer kit

Add the same number and size of vent holes to a pair of BT-50 to BT-60 centering rings.
 

BABAR

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Glad it worked. Assuming the sustainer motor is also 18 mm, the performance of the B6-0 and C6-0 has always seemed to me extremely underwhelming if not worse for anything other than minimum diameter rockets.

One of the worst was the MIRV, it had three sustainers (13 mm motors on sustainer, but still an 18mm plastic non-modifiable booster manifold.) The stack had far too much weight AND fin surface area for the available 18 mm Estes motors. Really hoping Estes comes out with a C5-0, as far as I am concerned they could just discard the C6-0 and replace it with the C5-0.

The QJets are nice, but I am not aware of any composite zero delay motors, I don't know if it is just too difficult from an engineering standpoint or what.
 

UhClem

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I can't remember ever seeing it done but I have heard tales of CHAD staged rockets. This is where you just tape a booster motor onto the regular motor. The booster motor falling free if it works.

Not recommended even if the rocket's stability margin allows.
 

UhClem

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The QJets are nice, but I am not aware of any composite zero delay motors, I don't know if it is just too difficult from an engineering standpoint or what.
There are composite zero delay motors but those are designed for RC. If by zero delay you mean that they burn through the upper motor like BP motors, then no. It wouldn't work the same anyway because while BP is brittle, APCP uses a rubber binder which isn't.
 

Scott_650

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Glad it worked. Assuming the sustainer motor is also 18 mm, the performance of the B6-0 and C6-0 has always seemed to me extremely underwhelming if not worse for anything other than minimum diameter rockets.

One of the worst was the MIRV, it had three sustainers (13 mm motors on sustainer, but still an 18mm plastic non-modifiable booster manifold.) The stack had far too much weight AND fin surface area for the available 18 mm Estes motors. Really hoping Estes comes out with a C5-0, as far as I am concerned they could just discard the C6-0 and replace it with the C5-0.

The QJets are nice, but I am not aware of any composite zero delay motors, I don't know if it is just too difficult from an engineering standpoint or what.
As UhClem mentioned, QJets use ammonium perchlorate based propellant which isn’t compatible with staging via ignition from a booster motor burn through - APCP sustainer motors are (now) typically ignited electronically with a flight computer of some kind and an ematch/initiator or something similar. Years ago folks used variations of cannon fuse light by the booster motor ejection charge but electronic staging/air starting is the accepted practice now.
 

BEC

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I was able to fly a Boosted Bertha with 24mm 1st stage with a C11-0 to A8-5 combo yesterday. The liftoff is *much* improved over the stock B6-0 or C6-0 first stage.

The conversion is pretty straightforward. You need a Boosted Bertha kit and:
Estes 3159 motor mount kit
Estes 9751 motor retainer kit

Add the same number and size of vent holes to a pair of BT-50 to BT-60 centering rings.
This sounds like an ideal approach. I've only flown my Boosted Bertha (which is stock) with a C6-0 in the booster a couple of times. Not the greatest result. No worries about the extra weight considering how stable Big Bertha is, and that the fins on the booster are even larger.

I can't remember ever seeing it done but I have heard tales of CHAD staged rockets. This is where you just tape a booster motor onto the regular motor. The booster motor falling free if it works.

Not recommended even if the rocket's stability margin allows.
I've seen this done quite a bit. Big Bertha is actually ideal for CHAD staging since it has lots of margin. There are a couple of folks at one club I fly with who really like CHAD (cheap and dirty) staging.
 

BABAR

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As UhClem mentioned, QJets use ammonium perchlorate based propellant which isn’t compatible with staging via ignition from a booster motor burn through - APCP sustainer motors are (now) typically ignited electronically with a flight computer of some kind and an ematch/initiator or something similar. Years ago folks used variations of cannon fuse light by the booster motor ejection charge but electronic staging/air starting is the accepted practice now.
electron for rockets is getting better and better and smaller and smaller, still a bit beyond practical for low power staging purposes to my knowledge.
Black powder staging is certainly low tech but carries its own challenges, particularly with long gap staging.

The first challenging is getting the booster ”blow through” flame to ignite the sustainer. Interestingly, with proper ducting and venting, THIS isn’t nearly as hard as it looks. I’ve done over 50” reliably.

the second and often unrecognized challenge is that the BOOSTERS on long gap staged rockets are often stable after separation, and even if they are not stable they are by definition somewhat larger and don’t tend to recovery well by tumble recovery. So you need some sort of system to deploy a recovery device on the booster. Electronics is not technically “out”, but at Least to me seems kind of silly to use low tech black powder for booster ignition and electronics for booster recovery deployment.

in any case, a C5-0 would greatly expand the Practicality of staging rockets with 18 mm motor mounts. It will probably stage LOWER than with a C6, but since most people are staging for kicks rather than altitude, the lower the staging the cooler the flight is to watch,

the exception would be my Apogee II, with I think a B6-0. My Dad and I watched the flight and saw the sustainer come down, never observed the staging even. Of course, after a short search the booster was found where we never expected to find it and therefore didn’t look for it…..it was still on the pad.

apparently it staged so fast our eyes just watched the sustainer go up while the booster slide back down the rod onto the blast plate!
 

BEC

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the second and often unrecognized challenge is that the BOOSTERS on long gap staged rockets are often stable after separation, and even if they are not stable they are by definition somewhat larger and don’t tend to recovery well by tumble recovery. So you need some sort of system to deploy a recovery device on the booster.
There was some handwringing on this forum about this issue and Boosted Bertha when it came out. I can say from close to two dozen flights (on a stock one) that the booster tumbles very nicely.

Now the Mongoose—that one's booster is stable and if one is ever presented to me as RSO/LCO I'm likely to not allow it to be flown unless the rod is angled way out away from everyone. We had the booster from one come in very near the LCO and RSO at Sod Blaster 3 over Labor Day weekend.

I do have one two-stager whose booster should tumble, but sometimes it glides—the Estes Sterling Silver (AKA Epic II from Hobby Lobby). So finding the booster is sometimes a challenge. All of the other two-stagers I fly with any regularity (Checkmate, Apache-2, Super Nova) as well as the accessory Booster-55 and Booster-60 all tumble as they should.

in any case, a C5-0 would greatly expand the Practicality of staging rockets with 18 mm motor mounts. It will probably stage LOWER than with a C6, but since most people are staging for kicks rather than altitude, the lower the staging the cooler the flight is to watch,
If they make a booster motor based on the current C5-3 that would certainly be the case. Its time-thrust behavior is very much like an A10T - big kick off the pad and a long tail of very little thrust. It also has less total impulse by a noticeable margin than Estes C6s. I'd be a little worried about something as draggy as a Boosted Bertha with a motor like that in the first stage....but we won't know what it really does if/until Estes releases a C5-0

the exception would be my Apogee II, with I think a B6-0. My Dad and I watched the flight and saw the sustainer come down, never observed the staging even. Of course, after a short search the booster was found where we never expected to find it and therefore didn’t look for it…..it was still on the pad.

apparently it staged so fast our eyes just watched the sustainer go up while the booster slide back down the rod onto the blast plate!
Apogee II is a pretty small model. It's hard for me to imagine leaving the booster (with a B6 in it) on the pad unless it had a rod hang or the booster CATO'd and lit the sustainer. A 1/4A.8-0 maybe....

I have been known to use 1/2A3-0Ts in the first stage of a Checkmate. This stages about 30 feet up.
 

bad_idea

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@BABAR I've seen several posts mentioning the desirability of a C5-0 vs. C6-0. Is the advantage that high thrust peak which comes on so quickly on the C5?

C5:


C6:

Edit: I think @BEC answered my question to his post which landed while I was composing mine. :cool: 👍
 

BEC

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I'm not him, but yes, that's the reason the C5 is desirable in heavy models.
 

BABAR

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There was some handwringing on this forum about this issue and Boosted Bertha when it came out. I can say from close to two dozen flights (on a stock one) that the booster tumbles very nicely.

Now the Mongoose—that one's booster is stable and if one is ever presented to me as RSO/LCO I'm likely to not allow it to be flown unless the rod is angled way out away from everyone. We had the booster from one come in very near the LCO and RSO at Sod Blaster 3 over Labor Day weekend.

I do have one two-stager whose booster should tumble, but sometimes it glides—the Estes Sterling Silver (AKA Epic II from Hobby Lobby). So finding the booster is sometimes a challenge. All of the other two-stagers I fly with any regularity (Checkmate, Apache-2, Super Nova) as well as the accessory Booster-55 and Booster-60 all tumble as they should.


If they make a booster motor based on the current C5-3 that would certainly be the case. Its time-thrust behavior is very much like an A10T - big kick off the pad and a long tail of very little thrust. It also has less total impulse by a noticeable margin than Estes C6s. I'd be a little worried about something as draggy as a Boosted Bertha with a motor like that in the first stage....but we won't know what it really does if/until Estes releases a C5-0


Apogee II is a pretty small model. It's hard for me to imagine leaving the booster (with a B6 in it) on the pad unless it had a rod hang or the booster CATO'd and lit the sustainer. A 1/4A.8-0 maybe....

I have been known to use 1/2A3-0Ts in the first stage of a Checkmate. This stages about 30 feet up.
In my case, when I talk long gap stage, I’m talking really loooooong, like at least 12” and really my standard is over 15” since I usually simply use the 18” standard length body tube as the booster section and about 2 or so inches is motor mount. Of course it varies with fin shape, but once the body tube length exceeds 2x the fin length, there is a good chance the booster is going to be stable AFTER separation, and this is one of those cases where stability is NOT a good thing. Kinda funny, as I remember Tim Van Milligan talking about gap staging being “possible” up to 11.5 inches (I had routinely done up to 36” by the time the article was posted.)

I have an idea I am working on that may work well, helicopter recovery of the booster. It’s gonna look a little bit like the Estes Flip Flier, but the upper stage will function for rotor retention on boost, releasing the rotors at staging. might even try the same with the sustainer. Anybody ever done a two stage helicopter with booster AND sustainer recovering by Helicopter?
 

BEC

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I have an idea I am working on that may work well, helicopter recovery of the booster. It’s gonna look a little bit like the Estes Flip Flier, but the upper stage will function for rotor retention on boost, releasing the rotors at staging. might even try the same with the sustainer. Anybody ever done a two stage helicopter with booster AND sustainer recovering by Helicopter?
Now THAT will be cool!
 

BABAR

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Estes website listed the max lift off weight for the C5-3 as 227 grams, just about double the C6-3


 

jmasterj

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Estes website listed the max lift off weight for the C5-3 as 227 grams, just about double the C6-3


Makes sense given the peak thrust is almost double.
 

Dotini

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I was able to fly a Boosted Bertha with 24mm 1st stage with a C11-0 to A8-5 combo yesterday. The liftoff is *much* improved over the stock B6-0 or C6-0 first stage.

The conversion is pretty straightforward. You need a Boosted Bertha kit and:
Estes 3159 motor mount kit
Estes 9751 motor retainer kit

Add the same number and size of vent holes to a pair of BT-50 to BT-60 centering rings.
A question, please.
If your 2nd stage weighed half an ounce over the 2.0 oz max lift weight permitted for the A8-5, would you still dare to use it because of your extra powerful new C11-0 booster?
 

waltr

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I would not have a issue.

Max lift off weight is a guide line that:
1- ensures high enough speed off the rod
2- allows the rocket to reach apogee near to the burn + delay times

With a two stage the sustainer already has speed so #1 is a non-issue.
Only question is if a 5 second delay allows the rocket to reach near apogee, very slow speed, so main chute deployment is not at to high a speed (either going up, delay too short or going down, delay too long.
 

WillMarchant

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Flight Video???
I tried, but we had a huge crowd of kids and somebody came up to me with questions right as it was launching. Now that it seems to work, I'll fly with some Jolly Logic gear to get actual data. And I'll try to get a video of staging.
 

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Kind of off-topic tangent here, but has anyone tried a Booster 55 (D12-0) with the Amazon from the Tandem-X launch set? Another low and slow rocket, and maybe a good low-altitude staging event as well? Some of the A.R.F.s that the Booster was designed for (2884 Red Rider, 2485 L.G.M. 0095, 2491 Drifter, 2492 Spirit, 2495 Chiller and 2497 Nova) are about the same spec weight as the Amazon.

 

GlenP

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Glad it worked. Assuming the sustainer motor is also 18 mm, the performance of the B6-0 and C6-0 has always seemed to me extremely underwhelming if not worse for anything other than minimum diameter rockets.

One of the worst was the MIRV, it had three sustainers (13 mm motors on sustainer, but still an 18mm plastic non-modifiable booster manifold.) The stack had far too much weight AND fin surface area for the available 18 mm Estes motors. Really hoping Estes comes out with a C5-0, as far as I am concerned they could just discard the C6-0 and replace it with the C5-0.

The QJets are nice, but I am not aware of any composite zero delay motors, I don't know if it is just too difficult from an engineering standpoint or what.
My kit bash of the SRW MIRV Gryphon was light enough for one C6-0 booster to lift and ignite 4 13mm (min. dia.) sustainers.

I lost sight of it filming and missed the staging event, but all four sustainers landed on the field.
 
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BEC

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Kind of off-topic tangent here, but has anyone tried a Booster 55 (D12-0) with the Amazon from the Tandem-X launch set? Another low and slow rocket, and maybe a good low-altitude staging event as well? Some of the A.R.F.s that the Booster was designed for (2884 Red Rider, 2485 L.G.M. 0095, 2491 Drifter, 2492 Spirit, 2495 Chiller and 2497 Nova) are about the same spec weight as the Amazon.

Glen,
The Booster-55 is set up to interface with the models that have a built-in screw-on motor retainer. Part of the package is a ring that replaces that retainer (that separate bit shown in the picture), which seats into the top of the Booster-55. I don't think the Amazon has the right interface. That said, I know you could probably figure out a way to adapt it.

On the original topic.....I'm surprised the A8-5 wasn't too long of a delay, but it's probably closer than using an A8-3 in the upper stage would have been, now that I think about it.
 

Scott_650

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Glen,
The Booster-55 is set up to interface with the models that have a built-in screw-on motor retainer. Part of the package is a ring that replaces that retainer (that separate bit shown in the picture), which seats into the top of the Booster-55. I don't think the Amazon has the right interface. That said, I know you could probably figure out a way to adapt it.

On the original topic.....I'm surprised the A8-5 wasn't too long of a delay, but it's probably closer than using an A8-3 in the upper stage would have been, now that I think about it.
Bernard is correct - the Amazon uses the twist on/off “bayonet” style retainer, not the threaded style. Wouldn’t be impossible to do - though the easiest way, glueing on one of the #2259 stager rings, would only work until it deforms from the booster motor burn through heat - then you’re pretty much stuck with cutting it off and mounting a replacement. But that would depend on if you ever get your Amazon back after a rather high flight 😉
 

BEC

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Glen has some mad building skills, though….so if he really wants to adapt it, he’ll figure out a way. :)
 

GlenP

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Bernard is correct - the Amazon uses the twist on/off “bayonet” style retainer, not the threaded style. Wouldn’t be impossible to do - though the easiest way, glueing on one of the #2259 stager rings, would only work until it deforms from the booster motor burn through heat - then you’re pretty much stuck with cutting it off and mounting a replacement. But that would depend on if you ever get your Amazon back after a rather high flight 😉
I think I remember that now, the existing motor retainer on the Amazon sustainer would likely get burned up after a launch or two, it is not really intended for staging and would need some modification, or have an alternate version made for staging flights while using the stock for single stage only.

Glen has some mad building skills, though….so if he really wants to adapt it, he’ll figure out a way. :)
Thanks for the vote of confidence, and the challenge. I have an idea, but would have been easier if I had not already built the Amazon and could have installed a more traditional motor mount with a metal retainer that would accept a staging coupler. Still could just use an external coupler, there might be enough room for that.
 

BEC

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I think I remember that now, the existing motor retainer on the Amazon sustainer would likely get burned up after a launch or two, it is not really intended for staging and would need some modification, or have an alternate version made for staging flights while using the stock for single stage only.
That, of course, is exactly how the Booster is intended to work—the supplied "stager" replaces the regular motor retainer on compatible models when they are flown with the booster, and the original retainer is used when flying the model single-stage.

Thanks for the vote of confidence, and the challenge. I have an idea, but would have been easier if I had not already built the Amazon and could have installed a more traditional motor mount with a metal retainer that would accept a staging coupler. Still could just use an external coupler, there might be enough room for that.
Yeah, that might work.

On a related note, I've wondered if one could get away with flying the MAV with a Booster-60, as the parts should be compatible....
 

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There was composite motors in the distant past that had 0 second delay for staging purposes. The motor was plugged with epoxy except of a hole drilled off to the side. You would stick a piece of thermalite into that hole and the other end will go into the the sustainers motor. The booster motor will ignite the thermalite just before burnout and if done properly and enough virgin rocket sacrifices were done beforehand, the second stage motor will ignite with the sustainer pointed in a safe direction.

Fun fact. Some of the early composite motors used this method for parachute deployment, the delay time was a fuse you set by adjusting the length of a fuse. Those motors resembled the German stick grenades in appearance.
 

Scott_650

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On a related note, I've wondered if one could get away with flying the MAV with a Booster-60, as the parts should be compatible....
Hmm…my MAV spent several months laying in a soybean field - the nose cone and fin can survived so it’s getting a stretched rebuild with a plain BT60 tube - but using the -60 Booster would be an interesting experiment - thanks for the idea Bernard!
 
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