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Using more powerful engines in the Alphas?

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LaunchPad

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This has happened to me twice and recently.

I decided to try C engines in two of my rockets.
One is an Alpha and the other is similar size.

Both times the engine and tube got pushed up further in the body.

Even though these size engines are suggested, I don't think I should go larger than A or B engines.
And the most recent one, the chute didn't deploy. Everything packed too tight?

Feel free to share any thoughts on this.
 

Titan II

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How is the engine and tube getting pushed up into the airframe? The mount is glued in and the engine is captive within it.
 

rstaff3

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Sounds like you need a bit more glue.
 

ksaves2

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How is the engine and tube getting pushed up into the airframe? The mount is glued in and the engine is captive within it.
If one uses too powerful a motor what LP describes certainly can happen. I had an old Big Bertha I taped a keychain camera to and stuffed an Aerotech RMS D motor in it. The shockcord broke, (I said it was old) and I discovered the same thing.
The motor was shoved up inside the bodytube a short ways as the thrust ripped it from the mount. Heck, this is a paper mount and not through the wall fins. The flight video was interesting and the AT 18mm D was right to overcome the weight
and drag. Am going to try another one with plywood bulkheads. Kurt
 

BEC

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Hmmmmmmm......I agree on the glue theory.

The peak thrust of an Estes C6 is only about 3 Newtons more than that of an Estes B6 (15 vs. 12).

I've flown stock Big Berthas and a Semroc Vega (same size model) on Aerotech D10s (peak thrust 25 N) with no issues....The Vega has a key fob camera on it and has for most of its life. The main issue with that is that a 5 second delay is too short and a 7 second delay is too long on the Vega/808 camera combo.
 

rharshberger

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This has happened to me twice and recently.

I decided to try C engines in two of my rockets.
One is an Alpha and the other is similar size.

Both times the engine and tube got pushed up further in the body.

Even though these size engines are suggested, I don't think I should go larger than A or B engines.
And the most recent one, the chute didn't deploy. Everything packed too tight?

Feel free to share any thoughts on this.
Pictures would be very helpful.
 

rstaff3

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If one uses too powerful a motor what LP describes certainly can happen. I had an old Big Bertha I taped a keychain camera to and stuffed an Aerotech RMS D motor in it. The shockcord broke, (I said it was old) and I discovered the same thing.
The motor was shoved up inside the bodytube a short ways as the thrust ripped it from the mount. Heck, this is a paper mount and not through the wall fins. The flight video was interesting and the AT 18mm D was right to overcome the weight
and drag. Am going to try another one with plywood bulkheads. Kurt
I have flown stock Estes kits on D21s. I have seen what the OP said using a D, but certainly not a C6.
 

Titan II

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If one uses too powerful a motor what LP describes certainly can happen. I had an old Big Bertha I taped a keychain camera to and stuffed an Aerotech RMS D motor in it. The shockcord broke, (I said it was old) and I discovered the same thing.
The motor was shoved up inside the bodytube a short ways as the thrust ripped it from the mount. Heck, this is a paper mount and not through the wall fins. The flight video was interesting and the AT 18mm D was right to overcome the weight
and drag. Am going to try another one with plywood bulkheads. Kurt
We are not talking about an overpowered rocket. Apparently the whole motor mount moved which indicates insufficient bonding. Simple fix.
 

ksaves2

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We are not talking about an overpowered rocket. Apparently the whole motor mount moved which indicates insufficient bonding. Simple fix.
Um, insufficient strength with paper centering rings. The Alpha from the OP might have been insufficient glue bonding. Kurt
 

Steve Shannon

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I would have been quick to say that a poor glue job was at fault also until I experienced two failures in a row caused by 15 year old epoxy joints. If the Alphas were recently built then yes, an insufficient glue job was probably to blame (poor fit, poor prep, bad glue). If the Alpha was older, then things sometimes just happen.
Fillets strengthen glue joints immensely. For a thrust ring you want a heavy fillet on the upper end of the thrust ring.
 

astrowolf67

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Just curious, in another of the OP's threads, it was mentioned that a rocket was lost in a field for a bit, and, had been rained on prior to being found. Was this the rocket that had been rained on?
 

rstaff3

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If the rockets in question were in the elements for a period of time, I agree that could be it. But the ones I've left in the field were obviously in pretty poor shape. I have a bunch of 30 year old rockets, built with white glue, which still fly fine on the standard LPR motors. Rotten rubber has had to be replaced. But I have always added good fillets and the one on top of the MMT assy is generally fairly hefty too.
 

LaunchPad

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I would have been quick to say that a poor glue job was at fault also until I experienced two failures in a row caused by 15 year old epoxy joints. If the Alphas were recently built then yes, an insufficient glue job was probably to blame (poor fit, poor prep, bad glue). If the Alpha was older, then things sometimes just happen.
Fillets strengthen glue joints immensely. For a thrust ring you want a heavy fillet on the upper end of the thrust ring.
For one of them, that is probably it since it is around 33 yrs old or so.
I've always just used standard Elmer's.
Maybe next time I'll try super glue when putting in the engine tube?
 

LaunchPad

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Just curious, in another of the OP's threads, it was mentioned that a rocket was lost in a field for a bit, and, had been rained on prior to being found. Was this the rocket that had been rained on?
No.
And after a refurbish of that one, it flew just fine today.
And BTW, that one is not an Alpha. I forgot what it's originally called since I re-named it Rock-It.
 

Rex R

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I have had centering rings fail once. it was my super alpha(bt60), I had changed it from an 18mm > 24mm mount, I used a set of rings from a mount kit. the flight prior had a late eject (with attempted core sample), the next flight (on a D12) the engine mount did a rear eject (it did manage to deploy the chute), when I looked at it afterwards, I found that the rings had failed leaving the Elmer's in the tube along with scraps of ring material. sanded out the glue and replaced the mount(using thicker fiberboard)and was good to go. I chalked it up to the core sample and an energenic ejection charge.
Rex
 

AlfaBrewer

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For one of them, that is probably it since it is around 33 yrs old or so.
I've always just used standard Elmer's.
Maybe next time I'll try super glue when putting in the engine tube?
Plain Elmer's is a great choice, especially the Glue-All. I wouldn't use super glue, as it gets brittle with age (much faster than Elmer's will). You can also use any wood glue, but it has it's issues - quick grab (often before you are ready)and coke bottling are the two biggest.
 
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