Estes Alpha III A8-3

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lucifer911
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Estes Alpha III A8-3

Postby lucifer911 » Thu Sep 24, 2015 12:07 am

Hey guys,

I assembled my Alpha III and launched it twice with A8-3 motors. The rocket is extremely light and fast off the launch pad. One thing I noticed was when I switched to the Estes wadding which is like square paper (see bottom left of attached picture) my parachute became damaged due to the ejection gases. I put in 3 pieces of this paper and the ejection gases got past it and burnt my parachute :(

The SCR recovery wadding shown next to the Estes wadding is much better and I have never had a single chute damaged from this.

Anyway I have put up a video on vimeo and I find this retains the GoPro video quality far better than youtube.

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Re: Estes Alpha III A8-3

Postby Lister » Thu Sep 24, 2015 12:31 am

Need 8-12 bits of wadding

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Re: Estes Alpha III A8-3

Postby lucifer911 » Thu Sep 24, 2015 12:44 am

Lister wrote:Need 8-12 bits of wadding


I am not sure if I can fit that many pieces in as the diameter and length of bodytube is pretty small. Maybe I could scrunch it up more but it has to be up against the sides of the body tube to prevent any ejection gases from seeping through into the parachute.

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Re: Estes Alpha III A8-3

Postby Lister » Thu Sep 24, 2015 2:39 am

Just keep wrapping around a scrunched up bit n scrunch it up and tap it in gently

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Re: Estes Alpha III A8-3

Postby kopius » Thu Sep 24, 2015 5:33 am

Just be careful with using too much of the paper wadding, I have seen many people with your same dilemma, first is a damaged chute, second is too much wadding it jams and the rockets crash. SCR wadding is specifically chosen because it just works and is hassle free.
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Re: Estes Alpha III A8-3

Postby Kryten » Thu Sep 24, 2015 9:42 am

Lister wrote:Need 8-12 bits of wadding

Well, that would make Mr Estes happy!
The guide for how much wadding to use is on the pack:
BT diam Recommended
mm number of sheets
19 2-3
25 3-4
38 5-6
42 7-8
66 10-11
You can use a little more than what is recommended, but as Kopius advised, do not use an excessive amount.

Also, from the Estes Technical Manual:
Loosely pack enough flame-resistant recovery wadding into the tube to fill it for a depth of at least twice the body diameter.
The wadding should fit against the side of the tube all the way around to give a good seal.
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Re: Estes Alpha III A8-3

Postby lucifer911 » Thu Sep 24, 2015 4:07 pm

what would happen if wadding is too densely packed and pushed all the way down to the motor mount tube with a dowel?
does it need to be pushed down all the way until it hits the MMT? my theory is if ejection gases have nowhere to escape then the body tube gets damaged or overheated.

Also I just tested the flame resistance of both these materials with a hand lighter. The Estes wadding pieces light up almost the same way as a piece of paper does... when I felt the material it doesn't feel very flame resistant to me. Honestly it feels like square pieces of paper towel with no flame resistance whatsoever.

I then held some SCR wadding over a flame and noticed it did not spread throughout the wadding unlike the Estes wadding.
Conclusion: SCR wadding is much better than Estes. SCR igniters are also better than Estes igniters too.

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Re: Estes Alpha III A8-3

Postby vance2loud » Thu Sep 24, 2015 7:26 pm

If wadding and/or recovery equipment is packed to tightly the ejection charge may not be powerful enough to eject your recovery equipment (parachute, streamer etc).
minimal force should be required to load your rocket, a dowel can be used but keep it gentle.
If unsure pack your rocket, remove the motor and insert a dowel to see how much force it takes to push it all out.
You will soon get a feel for how tight everything can be packed.
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Re: Estes Alpha III A8-3

Postby kopius » Thu Sep 24, 2015 9:33 pm

Additional to V2L's comments, something that needs to understood about explosives is that they are all lazy. By this I mean, they will always take the weakest path of resistance. Irrelevant of whether it is a rocket motor/ejection charge, or a plastic high explosive on a mine site, wherever the energy can escape the easiest is where it will go.

So for the practical lesson on ejection charges, when the propellant and delay element has burnt through, there is typically two places the ejection charge energy can go. As we all know, the plan is to go straight up to eject the parachute/nosecone etc. HOWEVER, some energy will always go the opposite direction as there is still a nozzle hole and empty chamber (aka motor casing) below. You will notice that the ejection charge area is larger than the nozzle and therefore the weakest path of resistance. In larger motors, you will actually notice the ejection charge sits in a concave chamber which has a small hole for the flame to get through. This chamber acts both as a larger (and therefore weaker) area and a shape charge channeling the energy in a more direct method.

So, what about the wadding packing... well if you pack the wadding down too tight, you will actually created a 'plug' that means energy will see the nozzle as the weakest path and that is where it will primarily go. It is very important to make sure you do not block off the path as to stop the energy going in the right direction.

Now that may sound like it is best to keep the wadding and recovery device (eg. parachute) up nice and high. Not correct. if you do that, a lot of the energy will dissipate before it reaches the wadding and therefore be less effective. You want the wadding etc. sitting close to the charge so it acts basically like a bullet, but not tight that is can't move.

Pretty simple right...
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Re: Estes Alpha III A8-3

Postby jase » Fri Sep 25, 2015 10:37 am

lucifer911 wrote:Also I just tested the flame resistance of both these materials with a hand lighter. The Estes wadding pieces light up almost the same way as a piece of paper does... when I felt the material it doesn't feel very flame resistant to me. Honestly it feels like square pieces of paper towel with no flame resistance whatsoever


Just to throw some more 'fuel on the fire' (PPP)...

There is a difference between Fire-Proof (wadding isn't considered to be Fire-Proof) and Flame-Retardant (wadding is considered to be Flame-Retardant)...

If you hold a flame to either material they will burn, remove the flame and they should self extinguish - so they are not fire proof but they will 'retard' the spread of flame. :wink:

Excellent explanation regarding ejection charges BTW kopius, that is a cool way of looking at it 8)
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Re: Estes Alpha III A8-3

Postby lucifer911 » Fri Sep 25, 2015 12:19 pm

thanks for the posts guys (kopius, vance, jase, lister etc)
I pretty much take 2 small palm size balls of SCR wadding and push one ball all the way down to the bottom with a dowel
and the second ball I just insert it with my hands and let it sit loosely underneath the parachute. So far no chute damage with SCR wadding and I've done about 10 launches so far.

Made a nice video of my chute deploying too:

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Re: Estes Alpha III A8-3

Postby Viking » Fri Sep 25, 2015 12:42 pm

Estes wadding is just toilet paper that has been soaked in either boric acid or a Borax solution.
If you look carefully you will see tear-off perforations in the sheets.
I have read an interview with Vern Estes where he states they used to get strange looks and questions from truck drivers when huge deliveries of toilet paper were dropped off at a model rocket company :D
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Re: Estes Alpha III A8-3

Postby lucifer911 » Fri Sep 25, 2015 1:01 pm

Viking wrote:Estes wadding is just toilet paper that has been soaked in either boric acid or a Borax solution.
If you look carefully you will see tear-off perforations in the sheets.
I have read an interview with Vern Estes where he states they used to get strange looks and questions from truck drivers when huge deliveries of toilet paper were dropped off at a model rocket company :D


honestly that is what it feels like. I found a video which probably explains how Estes makes their wadding.
[youtube]watch?v=sqlg-llf2oE[/youtube]

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Re: Estes Alpha III A8-3

Postby lucifer911 » Sat Sep 26, 2015 7:53 am

well I attached my keychain camera to the rocket like this but unfortunately I lost it high up on the tree.
kind of annoyed about it.. oh well guess we have all lost a rocket before.

I am wondering what colour rocket stands out most in a tree? obviously green would be the worst.
Would a fluro colour be good? maybe a shiny silver or gold coloured body tube would stand out?
the Estes Alpha III has fluro orange and I can tell you this does not stand out in a tree due to the sun causing an orange colour on leaves.


Here is the video of the lost rocket after launch

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Re: Estes Alpha III A8-3

Postby SpaceManMat » Sat Sep 26, 2015 12:18 pm

Lost my Alpha III the same way :x
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