Can I use 3 cesaroni spacers?

I want to start flying 1g to 6gxl cesaroni motors, but can I use 3 spacers so I can have 2 cases in total?

Not at the same time in the same motor.

They do have instructions.

Dosen't the 6xl case use a half spacer

crossfire said:

Dosen't the 6xl case use a half spacer

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I think what he is asking is if he can use 2 normal size + the xl spacer in the 6xl case so he doesn't need the 3 grain, 6 grain, and 6xl grain cases.

Even if you were to use the XL spacer plus 2 spacers, you only have 6xl, 6, and 5 in that case and 4-2 in the 4 grain. You'll need the 1 grain case.

I use the 6xl, 5gr, and 2gr cases to fly the whole set.

There's a thread on this forum about whether it is ok to use a 4 grain motor in a 6xl case (xl spacer and 2 regular spacers). I tried it and it worked. Not sure if I was just lucky.

billdz said:

There's a thread on this forum about whether it is ok to use a 4 grain motor in a 6xl case (xl spacer and 2 regular spacers). I tried it and it worked. Not sure if I was just lucky.

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As Bill testifies, it is structurally possible to use the case in that matter; however, that configuration requires 3 full spacers plus the xl spacer. There has been debate over whether the xl spacer counts as a full one or not, but using 3 spacers explicitly goes against the manufacturer's instructions, and would be considered a research motor unless approved in writing by Cesaroni. Was this done as a research flight launch?

Why does this rule exist? Mechanically speaking it is because the spacers create a compressed column within the motor case, and the longer a column is, the more it deflects under a given load. Spacer compression could lead to loss of sealing pressure within the motor leading to combustion product escape and case burnthrough. The manufacturer recognizes this and don't recommend more than 2 spacers

Does it work sometimes? Yes. Would it continue to work all the time? I don't know
I can't recommend cutting corners and foregoing manufacturer instructions to save a few 20's on the cost of a case.
(caveat being research launches by L2+ Tripoli members that Are aware and Accept the risks of their modifications in the company of others that also accept research launch risks. Key part being Aware of the potential risks created by user modifications of commercial hardware)

You may use two regular spacers or the XL spacer and one regular spacer in the 38 and 54 6XL cases.

No one reads instructions? Note that on the 38 and 54 there is one page for 2G to 6G cases, and a second page for the 6XL case.

https://www.pro38.com/pdfs/Pro29_Case_Spacer.pdf

https://www.pro38.com/pdfs/Pro38_Case_Spacer.pdf

https://www.pro38.com/pdfs/Pro54_Case_Spacer.pdf

Here is the old thread I mentioned, lots of different opinions and apparently inconsistent instructions: https://www.rocketryforum.com/threads/no-4-grain-motors-with-cti-6xl-casing-and-spacers.144110/

To fit a 4 grain motor into a 54mm 6xl case, you need one xl spacer and 2 regular spacers. With a 38mm 6xl case, you need one xl and 3 regulars.

delete...Bill beat me to it.

billdz said:

Here is the old thread I mentioned, lots of different opinions and apparently inconsistent instructions...

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Opinions are not relevant, and the ONLY instructions you should use are the manufacturer's.

As noted, there's a difference between 'structurally possible' and 'recommended and warranted by the manufacturer'. Research, all bets are off and you're on your own for however you stack things other than as instructed by the manufacturer.

So, it depends on the series hoe many spacers and which cases are the best to get.

CTI case stats.

You can fly 48 different 29mm motors with the 3 grain + 6 grain cases +2 spacers...adding the 6xl case gets you 4 additional motors.
You can fly 54 different 38mm motors with that hardware...adding the 6xl case gets you 9 additional motors.
Same number of motors (54+9) available in 54mm.

Whenever I feel the need to fly a 6xl motor, (hardly ever) I just borrow the 6xl case from a friend and offer to replace it if lost or damaged.

DaveW6DPS said:

Opinions are not relevant, and the ONLY instructions you should use are the manufacturer's.

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That's the issue, the CTI instructions say OK to use one XL spacer and 2 regular spacers (total of 3) to fly a 5G. See https://www.pro38.com/pdfs/Pro38_Case_Spacer.pdf, top picture on p.2, and 6GXL case instructions on p.2:
**
1) Drop the regular spacer(s) into motor case with the rounded end towards the rounded end of the motor.
2) Drop an XL spacer into the motor case.
**
The "(s)" in step one suggests it is OK to use more than one regular spacer.

DaveW6DPS said:

<snipped>....Compared to the manufacturer's instruction, each of those is one spacer too many.

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Hmm, the second page of the instructions clearly shows three spacers - 2 regular and an XL, for a total of three. So it seems pretty clear that three spacers is ok, as long as one of them is the shorter XL version. But it does not show 3 regular plus the XL, that does seem one too many.


Tony

billdz said:

That's the issue, the CTI instructions say OK to use one XL spacer and 2 regular spacers (total of 3) to fly a 5G...

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How is that an issue.
By CSI instructions, in 38mm 6GXL you can use 3 spacers to fly a 5 grain motor.
In your post(#9) you had a total of four spacers to fly a 4 grain reload. Where does it say you can use four?

In the instructions for the 54mm 6GXL case is says you can use 2 spacers to fly a 5 grain motor.
In your post(#9) you had a total of 3 spacers to fly a 4 grain reload. Where does it say you can use three spacers in a 54mm reload?

DaveW6DPS said:

How is that an issue.
By CSI instructions, in 38mm 6GXL you can use 3 spacers to fly a 5 grain motor.

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That's an issue because the NAR rules and several commentators say never use more than 2 spacers.

DaveW6DPS said:

Where does it say you can use four?

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Nowhere. I have never used four.

DaveW6DPS said:

In the instructions for the 54mm 6GXL case is says you can use 2 spacers to fly a 5 grain motor.
In your post(#9) you had a total of 3 spacers to fly a 4 grain reload. Where does it say you can use three spacers in a 54mm reload?

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Nowhere, and that's what started the discussion in the prior thread. I flew a 54mm 4 grain with 3 spacers and wondered why this was wrong.

manixFan said:

Hmm, the second page of the instructions clearly shows three spacers - 2 regular and an XL, for a total of three. So it seems pretty clear that three spacers is ok, as long as one of them is the shorter XL version. But it does not show 3 regular plus the XL, that does seem one too many...

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Part of the confusion is the differences in different case sizes.

29mm 6GXLdoes not have an "XL" spacer. You can use up to 2 spacers in a case.

38mm 6GXL for 6G reloads takes a regular spacer plus an "XL" spacer, with the "XL" spacer against the reload.

54mm 6GXL for 6G reloads only takes an "XL" spacer.

OK, sounds like the OP is trying to be able to fly the entire line of available motors with only 2 cases, a 3 and a 6XL. As per the instruction sheets, that's a NO GO for a NAR launch, and you're on your own if you do it at a TRA launch. The 6XL cases are NOT rated for a 4 grain load.

I think that the issue here is that there are 3 different sized motors, each with different rules and 2 different sized spacers: REGULAR SPACER and an XL SPACER, but everyone seems to be using the words 'motor' and 'spacer' without making the size distinction......which is CRITICAL to understanding the system.

29mm (2 through 6xl) MAX is 2 regular spacers (there is no XL spacer for 29) (can fly a 5, 6, or 6XL load in the XL case)

38mm (2 through 6) MAX is 2 regular spacers, never use the XL spacer in these cases
38mm (6XL case) ALWAYS use an XL spacer with anything smaller than an XL load, and a MAX of 2 regular spacers (can fly a 5, 6, or 6XL load in the XL case)
** XL SPACER ALWAYS GOES AGAINST THE PLASTIC MOTOR TOP CLOSURE

54mm (2 through 6) MAX of 2 regular spacers, never use the XL spacer in these cases
54mm (6XL case) ALWAYS use an XL spacer with anything smaller than an XL load, and a MAX of 1 regular spacer (can fly a 5, 6, or 6XL load in the XL case)
** 5g load REGULAR SPACER GOES AGAINST THE PLASTIC MOTOR TOP CLOSURE
** 6g load XL SPACER IS THE ONLY ONE THAT GETS USED

• Bottom line is that it is physically/mechanically possible to use more than the recommended number and configuration of spacers.

• Unless you are at a TRA launch and accept the lack of warranty, you cannot alter the spacer stack and fly a 4g CTI load in an XL case.

• A minimum hardware CTI set up to fly the full range of available motors would be a 3g case, a 6g case, a 6XL case, 2 REGULAR spacers, and 1 XL spacer.

DaveW6DPS said:

38mm 6GXL for 5G reloads takes 2 regular spacers plus an "XL" spacer, with the "XL" spacer against the reload.​

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Banzai88 said:

38mm (6XL case) ALWAYS use an XL spacer with anything smaller than an XL load, and a MAX of 2 regular spacers (can fly a 5, 6, or 6XL load in the XL case)

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Dave and Tom are correct, that is what the CTI instructions say, BUT the 38mm 6GXL CTI case (and every other case from every manufacturer) is only certified for a max of 2 spacers, see https://www.nar.org/wp-content/uploads/2014/08/CertifiedReloadableMotorSpacers.pdf

billdz said:

​

Dave and Tom are correct, that is what the CTI instructions say, BUT the 38mm 6GXL CTI case (and every other case from every manufacturer) is only certified for a max of 2 spacers, see https://www.nar.org/wp-content/uploads/2014/08/CertifiedReloadableMotorSpacers.pdf

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Then either CTI is wrong or the NAR chart is wrong. I'm betting that CTI knows their stuff, as their instruction sheets are much more precise in that they make a distinction between regular full sized spacers and the shorter XL case spacers.

That omission would make CTI 38mm 5grain loads in a 6XL case (which by CTI's instructions it's clearly capable of) non-NAR certified.

Time to kick this one up the chain of certification at NAR for clarification.

OK, posted the query to the NAR facebook group. Kevin Johnson, one of the Board said that he'd send it to the S&T committee. I also sent it to Mr. Lyngdal, S&T chair (message returned undeliverable) and to Mr. Pattisson-Gordon, S&T secretary, in hopes that SOMEONE has valid contact information for the S&T to get a clear answer.

DaveW6DPS said:

Part of the confusion is the differences in different case sizes.

29mm 6GXLdoes not have an "XL" spacer. You can use up to 2 spacers in a case.

38mm 6GXL for 6G reloads takes a regular spacer plus an "XL" spacer, with the "XL" spacer against the reload.

54mm 6GXL for 6G reloads only takes an "XL" spacer.

38mm 6GXL for 5G reloads takes 2 regular spacers plus an "XL" spacer, with the "XL" spacer against the reload.

54mm 6GXL for 5G reloads takes an "XL" spacer and regular spacer, with the "XL" spacer against the case end.

So the one exception is the 38mm 6GXL case where you can use an "XL" and two regular spacers, for a total of three.

If I recall, the 38mm stuff was the first to hit the market, with the 54mm a couple of years later, and then the 29mm a couple of years after that. So it seems to have changed with each size. And with the 38mm the aft closure comes with the reload and is single use. All the other CTI you have a durable aft closure...

See, nice and simple...​

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The certification of these motor products are under the preview of CAR. That said, the CTI instructions determine which and how many spacers can be used in assembling the motor.
Simply put, a flier must use a spacer configuration that is congruent with the reload instructions.

John Lyngdal
NAR Standards & Testing

I deduce from that that the CTI instructions are correct and the NAR spreadsheet needs updated and clarified.

Johnly said:

The certification of these motor products are under the preview of CAR. That said, the CTI instructions determine which and how many spacers can be used in assembling the motor.
Simply put, a flier must use a spacer configuration that is congruent with the reload instructions.

John Lyngdal
NAR Standards & Testing

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Thank you for the post!

Luckily this is only an issue with one casing, the 38mm 6GXL, and only when using a 5G reload.

I found 6xl, 5gr, 2gr, to be an economical sweet spot for me

I do not like to fly spacers with one grain reloads.

I have a couple of rockets that fly very nicely on 54mm one grain motors but the extra weight behind the CG of the bigger casing and spacer would make a big difference on them. I am particularly fond of the I140 Skidmark.

Per Cesaroni, 120 grams per spacer and longer casing, or roughly 4.23 ounces per spacer, 8.46 ounces if you use two.

Not many rockets designed for one or two grain motors will tolerate that weight without adding nose weight.

I find a 6G, 4G and 1G case work for me in 54mm.

For one of my 29mm mid power rockets, I am adapting down to 24mm with the Estes adapter. Since I have this now, can I use the CTI 2 grain case in this adapter?

Lukun7 said:

For one of my 29mm mid power rockets, I am adapting down to 24mm with the Estes adapter. Since I have this now, can I use the CTI 2 grain case in this adapter?

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Different topic, but I'll answer.

The Estes 24-29 adapter has a ridge inside the top end that prevents a 24mm blackpowder motor from slipping through.
You'll have to fit the case in and see if the Pro24 2gr will fit, otherwise you'll have to sand down that ridge which will render it useless for blackpowder motors again.

Some Aerotech 24mm single use motors do fit in that estes adapter.