Mach Speed Club

Discussions on high/extreme altitude and mach busting rockets.

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Sumo310
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Postby Sumo310 » Mon Jul 06, 2009 10:20 pm

Scoop1261 wrote:I guess when I started this thread it was really to see who had done what with what sort of construction...To show documented evidence of a rocket going Mach, and not some..... "I've got a ABC Pointybird Rocket and I'm gonna stick a J500 in it and I reckon it will go Mach...coz that's wot the sim says!"


Uhh...

Sumo310 wrote:Still to come are a set of PML launch rail guides, unfortunately along with the slimline retainer these will add extra drag, but that’s not such a bad thing. Simulations put this rocket to over 9000 feet on a J350W or J500G. The Cirrus Dart “should” bust through Mach 1 about 1 second after launch at around 700ft AGL. Rocsim says it’ll hit over Mach 1.30 on the J500G.


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Postby Sumo310 » Tue Jul 07, 2009 7:11 pm

Hi guys, time to post a serious reply now :D This thread has given me quite a few thoughts to digest, particularly drag on decelleration.

When I've run sims, I allow for a fairly generous margin for error of about 25% in all my calculations/results, to make sure the rocket will be fairly capable of breaking mach. Theres no reason for your sims not to be accurate with the appropriate provisions made, as previously mentioned. My sims have been compared to actual flight data, so I know what kind of accuracy I can expect - what a shock when my first altimeter flight came in 1000ft under what rocsim said!

Aside from my Cirrus Dart, I’m building a 3metre-ish, 4inch diameter rocket using an assortment of fibreglass and metal components including 4” Extreme(TM) glass tubing, a black brandt style nosecone and a 3 fin tail, with a 98mm MMT which is basically the lower section of the rocket that has been designed to accommodate any commercial 98mm motor available today. I had great fun in messing around with rocsim, to see what impacts various components, component dimensions, shapes and weights would do to a flights performance. My final design has ended up with components that have been flight tested past Mach 2 (or so the manufacturers say), so my build skills will be really tested if I fly this on something large. Unlike the Cirrus Dart, I intend to actually recover this rocket.

I've seen many similar rocket designs, which made me think there are certain recipes for mach and altitude flights. I've kept my build fairly simple as there will be enough going on when the rocket transitions through mach, and I reckon the less that can go wrong, the better. Time will tell if this philosophy proves right. If I'm wrong, I'm sure I'll learn the hard way.

I still haven’t figured out a way of ensuring the sections don’t drag separate without relying on shear pins alone. More thought will be spent here.

Then there is the video camera mount - I need to figure a way of filming the flight without impacting drag, or having wind pressure playing the avionics bay 'like a flute', to quote another thread.

Fin alignment will be another issue, but if Scoop is allowed to use a fincan, then why can't I? That takes 1 more variable out of the equation, as I can expect these fins to perform solidly. (See what I did there, its "reducing the number of variables", not "cheating" :P)

Some final questions:

1. What electronics are you all using to record your flights? I see Scoop is using a G-Wiz (amongst others), Hotspot has an rrc2? I've only used Perfectflite altimeters, and while user friendly, they don't offer anywhere near the information the G-Wiz offer.
2. Has anyone relied on GPS data alone to analyse rocket flights?
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Postby Scoop1261 » Tue Jul 07, 2009 8:18 pm

You can actually get the desired data from the Perfectflite altimeters by plotting the data into reasonably simple excel spreadsheet. After all the data is only a Time Vs altitude graph, that can be transposed to represent speed.

There are a number of commercial units currently available and in order of MY preferences

Ozark Aerospace ARTS 2
G Wiz HCX or MC2
Featherweight Altimeters Parrot V2
AED RDAS
Missile Works UFC-2

One of the cons for the RRC2 is that it only reports via piezo buzzer & is not downloadable (unless they have upgraded it)
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Postby hotspot » Tue Jul 07, 2009 9:23 pm

Think they are working on it dont know why not, maybe keeping the price down Scoops list looks like the way to go.

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Re: Mach Speed Club

Postby Scoop1261 » Tue May 25, 2010 3:37 pm

Hopefully this thread will get some extra posts after the Williams launch.

It will be good to see some raw data of flights exceeding Mach 1.0! 8)
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Re: Mach Speed Club

Postby Sumo310 » Tue May 25, 2010 3:52 pm

Based on some of the motors going up, I'm predicting we'll see some funky Mach 1.0+ lines, followed by a bunch of squiggles from rapid deceleration and disassembly.
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Re: Mach Speed Club

Postby PK » Tue May 25, 2010 4:06 pm

Sumo310 wrote:Based on some of the motors going up, I'm predicting we'll see some funky Mach 1.0+ lines, followed by a bunch of squiggles from rapid deceleration and disassembly.


That's optimistic!
Does ALL of the rocket have to go supersonic. Or just the bits on top of the exploding motor?

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Re: Mach Speed Club

Postby Scoop1261 » Wed Jul 13, 2011 9:37 am

Just a thought, but perhaps Nic, Simon & PH could post the data and a brief description of their respective rockets, both of which exceeded Mach at the recent WWW launch.

A photo of the rocket, screenshot of the data and a brief write up in a similar vein to the first post in this thread would be cool. 8) .....like I said......Just a thought!
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Re: Mach Speed Club

Postby cryoscum » Wed Jul 13, 2011 2:44 pm

Hi All

As suggested here it is:
My entry for Mach Madness this year was a fully composite 2 stage setup with a 54mm min dia K1100 first stage and a 38mm min dia J500 sustainer. Staging ignition was from below with a G-Wiz LCX also handling the booster's recovery. The sustainer had a Raven II on board. Both stages had a Whooshtronics Easy-as RDF on board and the sustainer had a small Mini DV camera in the NC.

photo1 (2).JPG
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photo.JPG
photo.JPG (168.23 KiB) Viewed 3501 times

photo1(3).JPG


This is the launch at Williams. The transition easily handled the forces and the ascent was solid and stable.

Soon lost site of it. First saw and then heard the J500 kick in. The booster soon came into view, fully deployed and landing quite closeby. Once the electronics were switched off there was an ominous silence on the radio where I had expected the second Easy-As to be beeping away.

There was a funny deviation in the J500 smoke trail when it fired and we all thought the sustainer had lost a fin, but, as it turned out, the NC decided to exit the party taking the Easy-As with it, hence the radio silence. At this point I had given up finding the sustainer as the RDF wasn't transmitting and there was no way to know where it had gone.

Then, driving to town to go buy some wine for the evening BBQ, imagine my surprise to see it lying next to the road in a paddock maybe 3km from the launch site, in plain view... It was then that we saw the NC had broken off at the shoulder taking the RDF with it and disconnecting the camera battery, but no further damage whatsoever. I was able to retrieve the flight data:

K1100_J500.JPG
K1100_J500.JPG (14.64 KiB) Viewed 3501 times


From the data you can see that the staging, though successful, was terribly timed. If the J500 could have kicked in at the exact time of peak thrust for the K1100, the sustainer may have gotten to Mach 3, nose cone missing or not.

This event caused me to more seriously look at NC manufacture (see the Whooshtronics section), but also to start thinking outside the box (to better kick Simon and PH's behinds next year!).

Cheers
Nic
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Total impulse for 2015: 84,231 Ns
Total impulse for 2014: 40,757 Ns
Total impulse for 2013: 62,927 Ns

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Re: Mach Speed Club

Postby Andrew Burns » Wed Jul 13, 2011 5:48 pm

Nic, you should probably have timed the ignition of the 2nd stage to occur well before burnout of the first, motors take time to come up to pressure after all and if the objective is pure speed then the thrust tail-off at the end of the booster burn is just wasted impulse (assuming the thrust levels at that point are no longer enough to keep the rocket accelerating). Will be great to see if there are any faster designs out there next year but I think that nobody is going to be able to go much faster than Simon and PH without getting a window to higher altitudes. Perhaps somebody should try to get video back from one of these stupid mach-experiments?

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Re: Mach Speed Club

Postby RobAust » Wed Jul 13, 2011 6:46 pm

Andrew Burns wrote:but I think that nobody is going to be able to go much faster than Simon and PH....
Hey Andrew, I think you just threw down the Gauntlet to Nic, he has already gone into testing mode for next years events and plans not to come home empty handed - hang onto your seats :mrgreen:
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Re: Mach Speed Club

Postby air.command » Wed Jul 13, 2011 7:29 pm

cryoscum wrote: There was a funny deviation in the J500 smoke trail when it fired and we all thought the sustainer had lost a fin, but, as it turned out, the NC decided to exit the party taking the Easy-As with it, hence the radio silence.


Image
Flight direction in this photo is right to left.
Crop Circles: ... just a bunch of guys looking for their rockets ....

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Re: Mach Speed Club

Postby Sumo310 » Wed Jul 13, 2011 9:22 pm

The Williams Wildfire Westernational Mach Madness 2011 challenge started for me when this was posted on the forum:

This is going to be too easy :mrgreen:


While Dave and I managed to throw a little attempt together, the author of the quote above pussied out, and the rest is history ;)

Fun facts:
Airframe: Carbon fibre, dual deploy from single section
Fins: Bevelled Carbon fibre
Nosecone: VonKarman, fibreglassed, small amount of weight added.
Motor: Aerotech J570W (38/1080 case)
Electronics: Raven 2 and Walston Transmitter
Altitude: 17,700ft
Velocity: 2970ft/sec (Mach 2.64 at sea level, 2.69 @ altitude). Mach 1.0 broken < 100ft AGL
G-forces: 112 G's
Recovered in perfect condition, bar a few scratches and bubbling of paint on the nosecone.

The rocket was not optimised for a single stage flight. We were hopeful of flying to 22,500ft using a J825R as a booster, and igniting the sustainer basically as the rocket left the tower. With the 18,000ft ceiling, we chose not to fly it in its staged configuration, reasonably confident that the single stage would get close to Nic’s speed set a day earlier.

Safety was a key issue in the design, we sacrificed length and weight in favour of stability. OpenRocket was used to ensure stability did not drop below 1.0 calibre. We had programmed the Raven to ensure the sustainer wouldn’t fire unless certain conditions were met.

The rocket - The nosecone shown was used to make the mould for the glassed cone:
MM.JPG


Flight Data:
38mm graph.JPG
38mm graph.JPG (36.4 KiB) Viewed 3456 times


Simulation data: - For an optimal 2-stage flight
J570-825.GIF
J570-825.GIF (38.56 KiB) Viewed 3456 times


And the video:
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Re: Mach Speed Club

Postby Scoop1261 » Wed Jul 13, 2011 10:08 pm

Andrew Burns wrote:Will be great to see if there are any faster designs out there next year but I think that nobody is going to be able to go much faster than Simon and PH without getting a window to higher altitudes.


There is opportunity to have windows up to 23,500 ft, however I need to know a substantial amount of detail some weeks prior to the launch to have the approvals in place.

If anyone is looking to use the extra airspace availability next year, feel free to either PM or email me to get an understanding of what is required for your proposed flight.

prefect@tripoliwa.org.au
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Re: Mach Speed Club

Postby MarkH » Fri Jul 15, 2011 8:57 pm

This is a great thread that just keeps on giving! Thanks for the flight profiles guys, great stuff...might even get me inspired for WWW 2012.


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