I infused PLA with KMnO4 and used it as a fuel core for rocket grade hydrogen peroxide. The PLA fuel core can be segmented, printed on a desk top 3D printer, and infused with KMnO4 at high temperature and pressure. The infusion takes less than an hour and results in the KMnO4 being evenly distributed throughout the PLA. I put together a small rocket engine using a 1/4 inch stainless steel mist nozzle as the HTP injector, a Soda Stream bottle for an oxidizer tank, a low pressure 12 V DC solenoid opening valve, a plastic one way valve, a graphite nozzle, and some CPVC piping glued together with CPVC cement. Primitive, but enough to demonstrate the catalytic reaction of HTP with PLA/KMnO4 fuel core. As long as I don't go over 100 psi chamber pressure and run longer than 10 seconds, it holds together long enough for the demonstration. I've written a paper on the HTP and PLA/KMnO4 hybrid rocket engine. I licensed the paper under the creative commons share alike copyright to engage in a dialog on this concept, if there is interest. Also, I've updated my website at www.fisherspacesystems.com. The website has a link to the paper as well as links to some engine test.
so this is basically a hypergolic hybrid motor using HTP and a permanganate filled plastic fuel grain?
you may want to try wrapping the fuel in some paper that has been soaked in a borax solution
Of the last five test in August 2021, the test on August 24 was the best. I increased the throat diameter to 5 mm, decreased the characteristic length to 33 in, increased the oxidizer tank pressure to 130 psig, increased the length of the fuel core to 16.5 cm, and added a pressure probe to the mixing chamber. Ignition occurred in 1.5 to 2.0 sec. The chamber pressure rose to ~93 psig in 2.0 sec and was steady throughout the ignition. Burn time was ~5 sec. The video (https://rumble.com/vlx4qr-08-24-2021-htpeplakmno4-chamber-pressure.html) shows a net positive thrust greater than 14 N (3.2 lb) at ignition and held throughout the burn time. Shut down was instantaneous. The oxidizer to fuel ratio was ~2.3 (2.5 theoretical) and total mass flow rate was ~13.4 gm/sec resulting in a characteristic velocity of 1,163 m/sec with a c* efficiency of ~77%. I still plan on launching a class I HTPE hybrid before the end of the year. Next month I'll lock down the thrust and begin building the flight system.
looks like you didn't have burn through problems this time either. did you have to add a heater for ignition this time?
you should correct the thread title from HYBIRD to hybrid.
Adding metal powder would interfere with the FDM propellant grain fabrication method, as hard substances in the feedstock erode the inside of the extrusion nozzle.
Solaire plans used dry ice to pressurize the fuel and HTP
How would the co2 be vaporised?
QuoteHow would the co2 be vaporised? I did a quick search on sublimation rate of dry ice. Most research is done for the packing and transportation industries at room temperature and atmospheric pressure. Very little research at 830 psi and room temperature. I looked at the Clapeyron-Clausius Equation but it contains an experimental coefficient. So, no matter what equation you use, some research is required. I plan on putting some dry ice in a stainless steel container, letting it come up to pressure, and measuring the change in pressure as I release the vapor through a stainless steel orifice. The diameter of the orifice will depend on how much gas I need to keep my tank pressurized. Once I have the coefficient, I can scale up to larger systems. There are additives such as ammonia to increase the sublimation rate if required.
Do you know what the effect of a longer residence time of the HTP on the ignition delay?
QuoteDo you know what the effect of a longer residence time of the HTP on the ignition delay?I'm not sure there would be an advantage here. Lowering the propellant tank pressure to below 120 psig introduces oscillations in the combustion chamber. I need at least a 30 psig pressure drop across the 12V NC solenoid valve, the check valve, and the injector nozzle to dampen out the oscillation. Also, the lower chamber pressure results in a lower thrust and characteristic velocity. Finally, the mechanics of starting out with a lower tank pressure then ramping up to a higher pressure would add more mass to the class I flight system. This may be feasible in a class II system but not in a class I system. Thanks for the comment.
...a slowly-opening ball valve instead of the solenoid?
Or printing a flow restrictor....
This month I showed that the class I engine performance was consistent, reliable, and ignition occurs in ~ 1.1 sec. The parameters were the same for each of the three test: propellant tank pressure, 130 psig; HTPE blend O/F ratio, 27.5, initial HTPE flow rate, 14.8 ml/sec; mass flow rate for HTP and ethanol, 19.7 gm/sec and 0.4 gm/sec, respectively; cross sectional area for the fuel cores, ~1.1 cm2 ; and the ignition "oxidizer" flux, ~ 17.6 gm/cm2 /sec. All three test used the same batch of distilled HTP with 2.0 ml of ethanol.The results were about the same across all three test. The average: ignition, 1.1 sec; mass flow rate, 12.4 gm/sec; chamber pressure, 105 psia; characteristic velocity, 1280 m/sec; efficiency, 86%, thrust, 16.5 N; regression rate, 0.23 mm/sec; O/F ratio, 3.0. Link to Nov 10, 2021 test https://rumble.com/vqb7of-htppla-hybrid-reliability-test.html. Read more in the November end of month report.
Try adding metal powder to your fuel and you might get better thrust.
Also, during my first test (with a 12.5 cm fuel grain) on the static engine test stand, I forgot to put a one kilogram mass on the rocket and it took off. I definitely need a pretest checklist. The liftoff was pretty cool. A video of the test is available at https://rumble.com/v13dp0n-liftoff.html.
Well, there can be no arguing with actual results.. Well done, Jerry!
use a simple catapult to assist with take off.
Or printing a flow-restrictor as part of the combustion chamber that rapidly burns away just after ignition.
spin-stabilise the rocket
.... but it's just as important (if not more so) to share what didn't work.
Anyone else getting shades of the Viper from BSG?
Gotta love those hypersonic inlets, for those times when you really have to dip into a planetary atmosphere.
the plastic bottle for construction/test purposes, or is that part of the flight vehicle structure?