248 replies to this topic

[aquarius]

Portfire, could you please post your specs for the 15 mm coreburner?

I am about ready to make up some 15 mm ID endburners with a 3 mm nozzle.
I would like to know your fuel/oxidizer ratio and what kind of charcoal you are using, as well as milling time.

So far I have had poor luck with endburners, and I burn my gray matter in search for the right formula and config.
My coreburners work like a charm, and it bugs me that I cannot get my endburners right...

[portfire]

Portfire, could you please post your specs for the 15 mm coreburner?

I am about ready to make up some 15 mm ID endburners with a 3 mm nozzle.
I would like to know your fuel/oxidizer ratio and what kind of charcoal you are using, as well as milling time.

So far I have had poor luck with endburners, and I burn my gray matter in search for the right formula and config.
My coreburners work like a charm, and it bugs me that I cannot get my endburners right...

They are some general specs in this thread somewhere.I haven't got my notes with me but i can get dimensions on the spindle tomorrow if you want?.

The fuel i use is standard 60/30/10 milled for 1hr then 10-20% fine(ish) charcoal (lumpwood) screened in.I used to mill for 30min+10%C,and although they flew,they were slow to takeoff.Increasing milling to 1hr really made a differance,blink,and its gone,but i'll say i'd like to get them somewhere in between.

I'v only ever made two endburners,one a upside down fountain,and i could crawl faster than the second.The thing is,when i started with rockets i made an endburner and a coreburner and with the "CB" working (almost) i went down that path,so can't really help you with that.

dean

Edited by portfire, 07 September 2007 - 07:24 PM.

[pyromaniac303]

I am about ready to make up some 15 mm ID endburners with a 3 mm nozzle.
I would like to know your fuel/oxidizer ratio and what kind of charcoal you are using, as well as milling time.

I've had success using 5/8" end burners, so slightly over 15mm in size.

The motor specs were 3" long casing, fuel was just willow meal powder, milled 4 hours, nozzle was 1/2" thick bentonite, then 2" of fuel and then more clay on top to seal it off. The nozzle on one was 2.5mm, the other was 3mm, and both flew well, in the 2.5mm version the meal powder had a small amount of 36 mesh aluminium added to it, so as this slowed the fuel down slightly I reduced the nozzle size to make up for the pressure decrease.

I rolled the tubes out of thick kraft, to around 4mm wall thickness.

These were made without any proper tooling, just a dowel, hand drilled nozzle, and flew to a very good height.

You sound like your along the right lines with what you are using, and the fact that mine worked is probably down to luck more than anything else.

End burners seem to get more reliable as you scale them down though, I have had great success with my 6mm end burners, but I have had a couple of 3/4" ones fail, and decided not to keep attempting large ones unless I find a more suitable test site for them.

[portfire]

Hi folks

Well i haven't had the productive weekend i'd have hoped for but,i'v just finished my second 19mm coreburner.

Some pics






I milled 50g of Karl's fuel for 1hr.I rammed this one(with support sleeve),in 30mm increments and then 20mm as i came to the top of the core.The tube held out really well,with no squashing (so now i'v a delay of 15mm+10mm e/plug) and with no real bulging.

I followed BrightStar's fusing method,which is basically what i do with my smaller rockets but,for some reason i opted for QM on the last 19mm

I did want to test it this afternoon but, (again) it's too bloody windy (for me anyway) so should get to test either later or tomorrow.

dean

[portfire]

Hi folks.Been a while,although i have been lurking here and there.

Anyway.I tested the second 19mm the other week-vid

http://video.google....994713235823130

It actually looks and sounds like a shell lifting.(i wish)

A bit more spectacular CATO (blew both e/plug& nozzle out) than the last.The vid doesn't do the thump justice and although i was disappointed,i went home with a smile on my face.

To me the fuel was way to fast and i suppose is a testament to just how reactive willow is.As i the case with rocketry though, there could be (or is) other factors causing the failure.Don't think i'm going to use willow in the next one and will probably go for lumpwood, same mill time and add 10-20% C.

On a more positive note,my 15mm coreburners are perfect (apart from a nice tail) and rise aswel as commercial ones.Now time for headers.

dean

[Pretty green flames]

Might as well post one of my rockets



20mm ID, 145mm Long with 10mm nozzle with the core being 95mm long. The fuel is 70:20:10 BP made with lumpwood charcoal + 10% Airfloat charcoal (Also lumpwood) added to slow it down a bit. It had a 142.70g dummy header to test if it could lift it (It did )

I'm very happy with my design.

Cheers

PS: Portfire, hope to see some footage of your rockets in action (With headers ofcourse )

[portfire]

PGF..WOW!! Excellent work...How jealous am i

Your 20mm are alot like mine,dimension wise.I may try your mix on the next one.How long are you milling?(if you are that is)and do you ram or press these rockets?

I was going to work on headers for my 15mm this weekend but after seeing that...Well

Don't worry BTW,as soon as i fire the first 15mm w/header i'll be uploading the vid the same night.I really wish i would have filmed the last couple of tests,quite somthing..oh well

dean

[Pyromaster2003]

The lift capacity for that rocket was excellent pretty green flames nice one.

Is that one of my tubes portfire looks like one, shame about the cato though. your next one will be better if you slow the prop down as you say look forward to the vid...im going rocket mad lately been making loads of 1" end burners they go like SH!T haha

[portfire]

[quote name='Pyromaster2003' date='Sep 27 2007, 09:15 PM' post='38217'
Is that one of my tubes portfire looks like one, shame about the cato though. your next one will be better if you slow the prop down as you say look forward to the vid.
[/quote]

Hand rolled I'v gotton rolling down to an art,almost.I really must sort some time out and make a tutorial.It may take a little longer than tradition methods but the way i roll tubes,you can roll a perfect tube 99% of the time

I have a 19mm tube ready so will give it another shot this weekend.Third time lucky

dean

[Pyromaster2003]

No way you must be lying lol good job on the tube looks quality.

[dr thrust]

hi portfire, nice tubes, i think your prob with you rockets is the same as i was having, and it boiled down to the ramming,dont make your increments so big! say 10mm at a time i know it takes longer but hey its worth to extra work, iam having rocket probs to! but at the other end of the scale where they have the power of a wet fart! just getting off the ground going 20 feet up then coming down like a dart into a load of mud, the fuel was from weingarts book kno3 16- c 12- s 3 way to much charcoal

so aim trying brocks now which is kno3- 13,c -6, s -2 , also meal 4 charcoal 1 , and kno3 72, c,24, s 2 and i'll see which is best

[Pretty green flames]

PGF..WOW!! Excellent work...How jealous am i

Your 20mm are alot like mine,dimension wise.I may try your mix on the next one.How long are you milling?(if you are that is)and do you ram or press these rockets?

I was going to work on headers for my 15mm this weekend but after seeing that...Well

Don't worry BTW,as soon as i fire the first 15mm w/header i'll be uploading the vid the same night.I really wish i would have filmed the last couple of tests,quite somthing..oh well

dean

The mix is milled for 25 minutes and the 10% Airfloat charcoal is then screened in. I ram these rockets.

Cheers

[portfire]

Thanx for the comments on the tubes guys,makes it a little more worth while I enjoy doing it anyway

Thanx PGF,i'll be making the third tomorrow.Hopefully with more promising results

Chris.When i started making 15mm rockets,i used to ram 1 ID thick increments and they always seemed to "chuff" in flight and although they flew pretty well,i couldn't figure out why they were "chuffing"(i did think i was using to many increments but,was following lancasters guildlines and thought,it's probably something i'm doing wrong) anyway,after chatting to another member on the matter he said try using fewer increments,so i did..and..no more chuffing (thanx again paul).I'm going on now so,anyway,this is the reason for the large increments and will use more,as you suggest,on the next.

Thanx for the help guys

dean

[portfire]

Hi folks.Here's the third 19mm.Should be firing tonight as the weather's looking good so far



I followed PGF's method with the fuel on this one and is rammed in 10mm increments.This one may actually fly but i'm not getting my hope's up

I'v also hand rolled (or attempted) some chrys#6 stars for the header on a 15mm.This is the second time iv rolled stars and i can say,its a bloody pain.The first attempt was just a black millet seed soap. This time though it was more promising but,the stars range from 2-6mm so i'm going to sort through them (another pain in backside) and try to roll the smaller one's up to size.I'v also got some 2" paper hemis for the 15mm headers but not sure i going to use them yet but,we'll see

dean

[marble]

Looks very nice, those tubes are hand rolled right?

Should make a basic start sizing plate, only takes a few mins to drills holes in plywood