Smoking

Most rockets leave a nice smoke trail to follow. A Hybrid running on Nitrous Oxide and a polypropylene fuel grain is almost smokeless. This makes it difficult to track visually. Does anyone have thoughts on tracking smoke for a hybrid rocket motor? At the launch at Thunad down Under to 26,220 AGL it disappeared pretty quickly once launched from the pad.

Things I wish I’d known before I started rocketry

1 Find yourself a mentor. There is a lot you need to know. Join the local club. Make friends with someone at the local club that you feel does your type of rocketry and ask them to mentor you. However hard it may seem it is a lot harder to learn from purely your own mistakes. You are still going to have failures. Heck NASA still has those. But you will make fewer mistakes and so have a lower number of failures. Or to put it another way. More successful launches. Norm

Designing Rockets suitable for Hybrids

Generally speaking a Hybrid motor is going to be a lot longer than a conventional solid motor based on APCP. Rattworks uses a UC valve fill system which can create very long motors. The M900 is 6 feet long. That’s a long motor. With the Rattworks motors you can take 3 basic approaches to designing your rocket. The first is a minimum diameter rocket. With a motor like the M900 this will tend to lead to designs with a L/d ratio of close to 50/1. This is generally considered to be the limit as it can lead to large buckling loads being imposed on the airframe. If you want to understand this take a long thin rod and press on the top of it while the other end is on a desk. You press up to a point then it buckles. When this type of force is applied to your rocket it happens much more dynamically. The rocket may experience a side wind as it moves through the atmosphere. This could start the bend and the load on the nose would finish the job off. This is one of the reasons l/d ratios over 50/1 have to be considered carefully. Also small diameter designs are difficult to successfully deploy a parachute from. There are ways to achieve this but you really need to test what you are going to do AND do what you test. A high l/d ratio generally gives rockets with multiple calibres of stability. This is a good thing isn’t it. Nope is isn’t. If your rocket is too stable then you can get big wind cocking problems easily. The next at the opposite end is a design based around a narrow core. You have the motor in the centre and arrange your deployment gear and chutes around it in a larger diameter design concentricly. This will result in a low l/d ratio. The problem you now face is that the stability of a design is specified in calibres of stability with 1 being the minimum difference between your cp and cg. the cg tends to go back on a Hybrid during flight as the Nitrous gets used. This depends on where the cg of your motor was in relation to the cp of your motor airframe assembly to start with. But the short of it is you need to know what is going to happen to your motor cg as it uses oxidiser. Also your parachute and other bits are going to move backwards under thrust. With a low l/d ratio this has the potential to result in an unstable flight. The third is a hybrid rocket for Hybrids. This is sort of an egg lofting design. A large diameter tube on top of a slender motor mount tube for the motor. I have gone for type 1 and 3 for my current fleet and Ron has gone for type 2 flying Hypertek Whichever way you decide to go Ron can advise you and I’ve flown the odd Hybrid too Norman Mcgeoch TRA 12957 L3 ( all on hybrids)

Rocket Photos

Mock up of how the final K3 rocket was going to look. All held together with PVC tape. 001 ebay gen lq

General view of the electronics bay. None of the expensive bits are in there yet.

ARRD attached to the end of the ebay bulkhead.

Electronics bay with a view of the ADEPT ALTS2-50k

A very reliable altimeter at a great price. You are going to have to find a dealer to ship this to you if you live outside the USA. He won't ship internationally. I used Ron at BlackDogRocketry.com to ship mine. The service from Ron was great and he consolidated all my shipping for me.

MARSA4 flight computer. This is really easy to program. It can all be done using the onboard LCD screen and multifunction switch. Too big for really small projects but great for everything else.

This is what happens to a slide switch from a plough into a field. Complete disassembly. The ALTS2 and MARSA4 both completely survived.

The spiral woung G10 tube had very little damage for something that had absorbed enough energy to take a 6 inch core sample of very hard clay soil. The end was cut off and it was flown again that day.

L1 Certification at Serpentine 2012

L2 certification on a RattWorks K240 at Serpentine April 2012

The K3 in its form for the certification flight. The big heavy fin can was designed to keep the altitude low. Still got to 9000 ft though. Not bad.

This is what roofracks were made for....

The Williams L3 Tattoo. Thanks Dave.

Thanks to Blake and Dave for being certification TAPs at short notice.

The next Stage was to Launch Karls ashes. No pressure then.........

Experimental self reloading hybrid design.

100,000 ft or bust.......... (this will only do 50,000 ft without the longer oxidiser tank. It'll do for a quick test........

Karls Launch update

On the weekend of 1st/ 2nd June 2013 the ashes of Karl McManus were launched at Williams Wildfire in Western Australia. The launch was a Tripoli WA launch. All scheduled events occured at the correct time. Flight was to 12000 ft and all of the rocket was safely landed about 700m away.

So long Karl.

Home

Hello and welcome to RocketScientist.com.au

This site was primarily about my journey to launch the ashes of my good friend Karl McManus who died of Lyme disease. You start out on a journey like this without realising the full implications, not least of which was to get Level3 certification for high powered rocketry. I chose to go the hybrid route as it seemed less expensive. It is less expensive, but throws up a number of other factors one of which is the complexity involved.

It has evolved into a site about hybrid rocketry and to prove that Hybrids are better than solid motor propellants.

This is NSW Rocketrys' Mullaley High Power launch site.

Pretty close to perfect.

[caption id="attachment_206" align="aligncenter" width="640"] Mullaley Launch Site[/caption]

Here's a video of my launch there

[embed]http://www.youtube.com/watch?v=3sluGB9Tn_k[/embed]

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About this Rocket Scientist

I'm Norm, This page is about rocket science generally and specifically about amateur high power rocketry involving hybrid rocket motors. I got into this by accident when I agreed to launch my friend Karl's ashes in the event of his death and he agreed to launch mine. Karl McManus died on 14th July 2010 and his ashes were lofted to 12000ft in June 2013. In order to launch to that height Tripoli Level 3 certification in High Power Rocketry will be required. I had a couple of attempts in 2011 to get along the certification process and found that I wasn't as much of a rocket scientist as I thought. The rocket I built while well-constructed was overweight and underpowered. There were many details I hadn't taken care of or was just unaware I needed to take care of. As Karl would have said "The devil is in the detail". I got my L1 and L2 certification in May2012. I previously had a backup plan to go to Williams in Western Australia in June and attempt my L1 and or L2 certification if there were any problems in May. I was now in the situation of just going to Williams for fun. So I decided to attempt my level 3 certification. The magnitude of work involved in attempting L3 certification is massive. While previously I had to pay attention to every detail, I now had to document every detail and have it scrutinised by 2 very experienced rocketeers called TAP's. They had to accept my design, construction materials, methods, the type of batteries I used and assembly and preparation procedures. At the same time they were preparing their rockets for the WA launch and Dave was preparing the event itself too. I shipped as much as I could to Western Australia 2 weeks before the event, but even then there was still a possibility I could have been asked to make changes to the final design by the TAP's so some large rocket bits had to be flown with me to Perth. The TAP's had a few final questions and then the paperwork was done. (I was up till 1am 3 times, and 2am on The Williams launch was a 2 day event. The first day was foggy till about 11am. My rocket now named K3 was assembled and ready to launch by about 1pm. The conditions were perfect. There was a glitch with the Nitrous fill system and Paul (PK) made the decision to go back to Perth and get some bits to make a new fill hose. Thanks Paul. I launched the next day in the mid afternoon. And the TAP's signed the paperwork to send to Tripoli USA. My L1 and L2 certification arrived a couple of days before I got my L3 through. I launched at Thunda down Under in March 2015 with a RattWorks M900 motor in a minimum diamater configuration rocket. 7:1 Von Karman nosecone. Apart from a small paperwork glitch the flight was flawless. Flew to 26,220ft and recovered 5 miles away 45 minutes later. I didn't get an on board camera fitted for the launch. Had I known there was no standing Hybrid record for an M class motor, I would have put the application in and have it. Hey ho... Next time. [caption id="attachment_229" align="aligncenter" width="480"]

RATTWorks M900 min dia to 26,220 feet Above Ground Level landed safely.[/caption] [embed]http://www.youtube.com/watch?v=3sluGB9Tn_k[/embed] [easy_sign_up title="If you'd like full size copies of any photo. Send me your details below." phone="1" fnln="1" esu_label="Photo Request" esu_class="your-class-here"]

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