11 replies to this topic

[Professor]

Well after a month or so flying the tiny "ready to fly" kits in back garden, i bought 3 estes kits and decided on the "fatboy" as my first rocket as it had the lowest altitude of my 3.

Anyhow being my first build and launch i decided to not bother too much with sanding/filling and painting (kinda pessimstic on chances) so it was white cardboard and balsa all the way.

We was in a local field in a residential area (with permission) about 400ft square only and a slight breeze (5-10mph) 3..2..1 and she was off like a shot straight and fast (yes!!), ejection seemed good and out popped the chute (standard kit chute but i cut the spill hole out to speed descent) Now i lost sight of it for a split second and when i saw it, she was drifting in the wind, and drifting, oh and er drifting (bad!!) a friend rushed off at sprint pace to try keep eye on descent as it neared houses (gulp) when we cuaght up the rocket was at the top of a tree in some poor guys garden 2 roads away, very nice chap, we did recover it with some tree climbing and bamboo work!

So all in all, i am already hooked with one launch and can see this hobby going to be the one for me, on the downside really need somewhere more suitable to launch, as even with 5 motors i decided to no-more launches today as was lucky it was in a tree out of harms way. Permision to join the world of model rocketry?

But your advice, firstly how much drift from a streamer would i get? was thinking of making a streamer tomorrow at home and seeing if can get it back in same field. Even with the large spill hole i was amazed at how far it drifted. And secondly (UK guys) any ideas or recommendations on where could possibly launch from, are any parks / councils or open land sympathetic to rockets? I realise there are clubs and launch events which is great, but really to enjoy this hobby i need to launch more than a couple of times a year (dry weekends be good). For info i am in Kent / Sussex border near tunbridge wells. Would be a shame to have a interest and hobby to be ruined by not having a place to "play" (sorry luanch!) I soooo wanted to do some more launches today but didnt want to risk it again.

Anyhow i am hooked already, and will be building my other 2 rockets soon (blue-ninja and mercury redstone) after those hopefully onto scratch builds.

(apologises if read twice, posted on TRF also)

[richard]

Hi proff
Dont know what happened with the last post no text was added.
nice to know you have had success, trees seem to have a magnetic effect on rockets, one of my last launches ended up in tree, still it was retrieved quite easily, the last flight of the day ended up with chute cords welded together so a rather heavy landing was had and a severly loosened boattail, still thats what pva was made for.
I prefer streamers with smaller rockets, they dont tend to end up quarter of a mile away.
Have you thought of getting some tubes and starting from scratch, there are quite a lots of designs on the net, i bought a pack of bits off a chap the other day and hope soon to get started with a fresh design and see what happens.
if you have a look on the rocket reveiws site there are quite a lot of tips and also a flight log if that sort of thing interests you
My next launch hopefully will be the 36 d squared, I will report on that shortly
best of luck with the launches

[fishy1]

should you really be using rockets in a 400 square foot area? even with permission, thee's houses nearby.

By my calculations, 400 square feet is a square 20 feet by 20 feet. this means, you are firing in a 7X7 metre square (If a square). I feel this is inadequate, what if it tipped over? You mentioned it travelled 2 streets when decending. What if it fell on a moving car and caused a crash?

Edited by fishy1, 12 July 2006 - 09:09 PM.

[minalth]

By my calculations, 400 square feet is a square 20 feet by 20 feet.

im hoping he ment 400' by 400' which would be 160000 square feet

i think thats what 400 feet square means rather than 400 square foot...

minalth

[fishy1]

I googled feet square and yes, it's 400' by 400'.

[Professor]

Yes indeed i meant 400 x 400 (albeit approx, its probably far bigger)
And i am certainly be cautious, hence after that huge drift i ruled out any other launchs due to safety.

Was hoping for some trials this weekend, but its very gusty round here and no chance this weekend it seems sadly.

[leosedf]

Yesterday i fired two small rockets.

One with a BP salute (I don't like flash powder) and one with some aqua stars.

The first is here .
And the second is here

Sorry no prefire pics.
The tubes had an ID of 14mm and where 12cm long, both of the payloads weight was 30gr. The star payload had a really crappy break but anyway.... One step at a time.
I'm still trying to find out a way to lift a new payload (90grams), maybe use a core burner?

[karlfoxman]

I have lifted a 4" spherical shell using a 3/4" core burner. It worked and looked great, you need to fine tune your rocket propelant so its not too fast it explodes but just under. That way you get max thrust and minimal CATO.

[leosedf]

Hmmm...
The largest ID i have is 16mm, what if i use 16mm ID with a fast BP End-burner?.
I use standard BP (75:15:10) with willow charcoal on all my end burners.

Edited by leosedf, 08 August 2006 - 10:14 AM.

[aquarius]

Could any of you more seasoned in rocketmotor building please post some spec's for BP-motors?
I have tried the standard 1/2 inch Wolter tooling (made on my lathe) but it violently CATO'ed.
Maybe a tube failure, the whole thing just disappeared in smoke...

[pyromaniac303]

Could any of you more seasoned in rocketmotor building please post some spec's for BP-motors?
I have tried the standard 1/2 inch Wolter tooling (made on my lathe) but it violently CATO'ed.
Maybe a tube failure, the whole thing just disappeared in smoke...

What ratio fuel are you using? For my 1/2" tool set it has a 3.5" core forming spindle and I get away with around 65%-70% kno3, 10% sulphur and the rest charcoal, often mix in 5% extra unmilled hardwood charcoal for a tail after the rest has been in the ball mill for 2-3 hours, and with this I have not had any CATOs. Before I started using proper tooling I had a lot of CATOs and some underpowered ones that barely took off.

Also what wall thickness on your tubes? Anything around 3mm is usually more than enough.

[aquarius]

As for the fuel I have tried 70:20:10 with and without 5 % MgAl. (Alan Yates RP)
And I guess I do it the same way as you, I ballmill a mix of "70:10:10" first, and then add the extra 10 of coarse charcoal, dampen and press. Once dry, I mix in the MgAl.

(Have also tried the standard 60:30:10, as well as plain BP, but not on this tooling.)

I roll my own tubes around a 12 mm rod, ID 12 mm, OD 19,5 mm, approx 3 mm plus walls.
Nozzle and bulkhead from bentonite catlitter, cheap and works well.

I have "copied" the Wolter tooling on my lathe, but it seems I migth have to shorten the length of the core.

Now I am trying out a design with good results from earlier testing, 12 mm ID, 4 mm nozzle and a short 20 mm corelength.
The problem with such a short core and narrow nozzle is less lift/shorter thrustperiod, resulting in little lift capacity.
Will try to adjust the corelength until CATO and go back to a safe configuration.
And maybe then continue with 5 mm nozzleopening and core diametre, depending on success and time to spend..

Any comments or tips are welcome!!