G80 FWL ignition problem (solved)

[5thDay]

Last week I launched a modified Estes ESAM-58 model rocket with one of these on a 6foot 3/8" thick rod. Though the flight was a success, the velocity off the rod was extremely low as the thrust came in puffs until it fully "lit?" and took off nearer to what looked like maximum impulse. Had I used a shorter rod, it would almost certainly went sideways as it literally slid downwards on the rod twice before taking off.

The video attached is from the same batch using an identical ignitor and the same launch equipment (electronically speaking).

No outer labeling or logos
No thrust ring 29mm SU motors
Paper Label over the ejection charge says "Aerotech White Lightening G80-10FWL" which I have researched to mean Fast White Lightening"
AeroTech 4" Copperhead Ignitor *purchased seperate*
12V 9.5Ah Battery 3' away activated via relay
Clips are standard flat smooth clips with a style paper separator

This test was recorded to try and recreate this... (slow start?) condition and to see the nose cone ejection velocity in the HDPE MD rocket I am working on. Has anyone else seen something like this? I only have a half dozen of composite motor launches under my belt and have only seen this on these G80s.

 

[rharshberger]

Puffs or Chuffs, a sputter at startup is usually known as a Chuff...the rocket can pogo right off the rod...scary as hell went its an HPR

 

[5thDay]

Thank you for the terms. That should help me forum search more information about it and ways to prevent it.

My future large diameter rocket launch rod has Soyuz style hold downs in the design for clustering which I may now revisit with chuffing in mind.
* Or not based on the advice below. re-evaluating *

 

[jimzcatz]

Sounds like improper ignitor placement. Do NOT use any type of hold downs.

 

[StreuB1]

Like Jim stated, sounds like the ignitor was installed at the middle/bottom and not at the head of the grain perforation.

Ditch the copperhead ignitor and use a more robust ignitor like the current AT production ignitors.

 

[5thDay]

Thank you everyone. I will add a few extra First Fire/First Fire Jr to my cart for my next purchase.

Both times it felt like I bottomed all the way out, and I like to pull it back out after I feel that to make sure the thin strip is straight before a final re-insetion. From the look of the 2-wire style, I can already imagine the difference in robustness even without seeing any spark front differences.

I had 4 of these and after a scary launch on the first one, I will do another test fire with better ignitors before flying the last one in such a dart of a featherweight rocket as this is.

 

[Tractionengines]

Old white lightning motors develop a layer of oxide where exposed to air. (The hole or slot were the igniter goes.) So they are "harder" to ignite than new. "Carefully" scrape it with something and it will light easier.

Note the type of propellant has an affect, on how they age, too. Blue will still light easily, white ok a little slow, green really slow.

This was an OLD Green...watch all the way to end.

 

[dhbarr]

Thank you everyone. I will add a few extra First Fire/First Fire Jr to my cart for my next purchase.

Both times it felt like I bottomed all the way out, and I like to pull it back out after I feel that to make sure the thin strip is straight before a final re-insetion. From the look of the 2-wire style, I can already imagine the difference in robustness even without seeing any spark front differences.

I had 4 of these and after a scary launch on the first one, I will do another test fire with better ignitors before flying the last one in such a dart of a featherweight rocket as this is.

You can tell if you got all the way up by test inserting, marking the lead, and holding next to the motor outside the rocket.

I like to do this at home, then tape that igniter to the outside of that motor. When it's time to put the motor in the rocket, I tape the igniter to a fin. When the rocket is on the pad, I slide the igniter in up to the mark from home.

 

[StreuB1]

Old white lightning motors develop a layer of oxide where exposed to air. (The hole or slot were the igniter goes.) So they are "harder" to ignite than new. "Carefully" scrape it with something and it will light easier.

Note the type of propellant has an affect, on how they age, too. Blue will still light easily, white ok a little slow, green really slow.

This was an OLD Green...watch all the way to end.

That is one of the funniest videos I have seen in a while. The LCO giving commentary on the plight of the motor is the best part.

The ending.....pure gold "....we understand that is a motor you bought from the Wildman?"

 

[SecondRow]

Old white lightning motors develop a layer of oxide where exposed to air. (The hole or slot were the igniter goes.) So they are "harder" to ignite than new. "Carefully" scrape it with something and it will light easier.

Note the type of propellant has an affect, on how they age, too. Blue will still light easily, white ok a little slow, green really slow.

This was an OLD Green...watch all the way to end.

I think this is the main driver of the chuff OP experienced. By OP’s description, it’s an older WL motor (no thrust ring 29mm and copperhead igniter). @5thDay, make sure to give the grain a careful scrape.

 

[5thDay]

@SecondRow will do, thank you.

Turns out after more searching that these are a 'wee bit' aged. The date code is in reload format and not YMDDMY that SU are being reported using.

61197

06/11/1997 - 25 years of oxidation?

Bought from another Arizona rocketeer. Happy they light at all.

** Copperhead ignitors purchased separate so shouldn't be used to determine age. I should have added that in OP. **

 

[rharshberger]

@SecondRow will do, thank you.

Turns out after more searching that these are a 'wee bit' aged. The date code is in reload format and not YMDDMY that SU are being reported using.

61197

06/11/1997 - 25 years of oxidation?

Bought from another Arizona rocketeer. Happy they light at all.

** Copperhead ignitors purchased separate so shouldn't be used to determine age. I should have added that in OP. **

I like to sand the slot with a piece of 80-100 grit sandpaper prior to assembly on any motor old enough to have a Crapperhead ignitor (and other old motors too).

 

[Tractionengines]

Look at post #19 in this tread....only funny to watch since the last chuff went straight. If it had tipped over.... could be another story.

IF I remember right: This was another OLD motor that was expected to "have issues". So it was done "heads up" and everyone was watching to see what happened.

https://www.rocketryforum.com/threads/chuffing-motors-what-is-going-on-there.162624/post-2061377

 

[dhbarr]

I like to sand the slot with a piece of 80-100 grit sandpaper prior to assembly on any motor old enough to have a Crapperhead ignitor (and other old motors too).

I like an infant emery board, goes right into the motor slot.

 

[AeroTech]

@SecondRow will do, thank you.

Turns out after more searching that these are a 'wee bit' aged. The date code is in reload format and not YMDDMY that SU are being reported using.

61197

06/11/1997 - 25 years of oxidation?

Bought from another Arizona rocketeer. Happy they light at all.

** Copperhead ignitors purchased separate so shouldn't be used to determine age. I should have added that in OP. **

I was going to say, those are over 20 years old…

 

[bjphoenix]

I have a variety of old motors I'd like to be able to use- some 24mm reloads, 29/40-120 reloads, one G80, a couple of econojets. After reading various threads I'm thinking I should do some static ground tests first. I was thinking I could piece together a stand from some scrap wood, clamp the motor/casing to it and have it exhaust straight up. I could have solid wood between the motor and the spectator(s) as shielding.

 

[Tractionengines]

I have a variety of old motors I'd like to be able to use- some 24mm reloads, 29/40-120 reloads, one G80, a couple of econojets. After reading various threads I'm thinking I should do some static ground tests first. I was thinking I could piece together a stand from some scrap wood, clamp the motor/casing to it and have it exhaust straight up. I could have solid wood between the motor and the spectator(s) as shielding.

How old is old??? If just a few years, in sealed pack, just fly them. If "OLD" (like these that are 20 years +) then be cautious.

With OLD motors ... Once you ground test "a" motor, you only know what "that motor" was going to do... another one, identical to the one tested "MAY" perform the same, but maybe not... and that maybe is only if they were exactly the same type of motor, of the same age, and stored inthe same exact location as the first.... if it's different at all, (even in just how well the package was sealed) it WILL perform differently.

I would just carefully scrape the core slot(s) to help it get going; use a new igniter (maybe slightly enhanced); fly it in a rocket with "no sentimental value"; from an "away pad"; with the rod definitely angled slightly away from people/property.... hope for the best.

Remember delay timing could be "way off". So anti-zipper design would be good. Or use an Eggtimer Apogee for deployment. If it gets lost; or taken out by a cato, it's relatively low cost..

As always YMMV. Be Safe, and have fun.

 

[5thDay]

By no means am I an expert but I would like to offer some experience with setting up test firing rigs. You may have considered all I am going to mention but I get the impression from the quote below you have not done something like this before so I wanted to volunteer some forces you may have not considered.

I'm thinking I should do some static ground tests first. I was thinking I could piece together a stand from some scrap wood, clamp the motor/casing to it and have it exhaust straight up. I could have solid wood between the motor and the spectator(s) as shielding.

Clamping is a term that makes me nervous (from experience) when describing a stand or rig to do test fires. SU motors get warm and I have seen deformation whenever my mounting solution was less than ideal. Clamping can not fully work when the clamped object becomes flexible. (Yes, looking back on past behaviours I am grateful nobody was hurt and that cell phone videos were not a common thing!) building an exaggerated MMT with an engine block gives you a lot more ability to secure the motor and when I say exaggerated I mean duplicate the ID but keep in mind that the stand doesn't fly so go nuts on wall thickness, density and size. Try researching "test stand" or "load cell" and look at various mounting options. Don't forget motor retention and ejection gases when over engineering for predicted engine thrust in a single direction.
There is a YouTube video out there I stumbled onto years ago where someone strapped an Estes F15 to an anvil resting on a picnic table. 5, 4, 3, 2, 1... and the video is just a picnic table! Downward firing like you mentioned is one way to control this force but is there any potential for sheer or horizontal force in your base? Something incredibly sturdy in one direction doesn't necessarily prevent it falling over and 'scouting' along the ground with minimal friction. Nothing has to break or give in that example or in the anvil resting on a picnic table example. It just has to have force applied to it that wasn't accounted for or protected against in design.

 

[5thDay]

I was going to say, those are over 20 years old…

Aerotech read and replied to one of my posts!

wow