arun wrote:ravi_g wrote:
Ok now this could be the answer.
The Prithvi used UDMH (stable). but the problems seems like was because of Oxyacid route to oxidation. Seems like we use Nitrogen Tetroxide a lot for our rocketry and missiles. During production and usage NTO needs to be cooled to a liquid form and then during the production process Nitric Acid is also produced which is also an oxidizer and is also used in PUREX.
Good thing they messed around with the fuel instead of the oxidizer.
From what I can make out the liquid propellant used by the Prithvi is not UDMH.
The Hypergolic fuel aka “G Fuel” used is Isomeric Xylidine (50%) plus Triethylamine (50%).
The Oxidiser aka “O Fuel” used is Red Fuming Nitic Acid (RFNA) with Phosphoric Acid (H3PO4) and Hydrofluoric acid (HF) added as corrosion inhibitors.
See this link from the OFB:
Clicky
Thanks for pointing that out.
The Mix you are talking about is the Samine/Tonka. Also very old (German). I had read that during the Kerosene days of Scuds this was used as the starter fuel. I reached the wrong conclusion that this fuel was only meant as a starter. Apparently there are a lot of missiles (Non western) that use this combination.
Amines & Samines are the situ or the base materials on which Hydrazines (UDMH) are maide. So the Samine fuel should be usable as the base for other hydrazines (other then UDMH). Even for UDMH the Triethylamine you are talking about is one of the recommended inputs for certain processes.
This Samine/Tonka is the other route to getting some of the fuel characterstics of UDMH but much more toxic and somewhat poorer ignition characterstics compared to UDMH. Apparently in one of the old methods of UDMH manufacturing (Nitrosamine/Nitroamine) the amine usage was found so risky for workers that they had to shut down the plant for good in US and US moved wholescale to UDMH/MMH by Chloramine which required one more step but the production process was safer and so was the end product with lower freezing point aka good for Himalayas and space use & other low temp applications requiring long storage times.
Actually I never went on to read flame characterstics nor did I read about Isayev engines. Thanks to you now I know something about these too. Engines and Flame characterstics should have made it clear had I reached that part of reading.
PS:
Also as an add on info. Indians had a 3.5 ton Hydrazine (old risky variety) production capacity in 1973 and lab capacity for UDMH. By 1986 it seems Indian scientists were very confident of all varieties of Hydrazines and this Samine fuels and had already begun working on newer varities but this new thing seems to have petered out as one of the material (2012) I read was also discussing the exact same position. DRDO seems to have moved focus out of this area. Not that, that is bad, though.