alkane + HNO3 is how the lower aliphatic nitroalkanes are made in industry. this is not suited for most people but if you like to build things...and it doesn't seem that there are simpler alternatives using these alkanes.
you get a mixture of nitroalkanes with ethane and the ratio of products is highly dependent on conditions. high temp vapor-phase is generally used, probably multi-pass as well, i don't remember. see
Patent US1967667
for why a more convenient method isn't around, AFAIK. you could probably find more with a "referenced by" search of the patent databases, this is the classic patent on this.
ten years ago i read a great Ind. Eng. Chem. article full of yields of various nitroalkanes under various conditions from methane to butane, in neat tables. a definitive article with much text as well. and came away thinking...silver nitrite and ethyl iodide. but i dont remember which article and of course you ask on a day on which all libraries are closed in the usa!
the inventor of vapor phase nitration, Hass, has a lot of Ind. Eng. Chem. articles, and some in JOC and JACS. his name got a lot of hits in TFSE, btw. so i don't know which of the following is best for the industrious, able bee, if any. all are by Hass, industrial methods not very well suited for most but you get the idea, and in Ind. Eng. Chem:
nitration of ethane:
32, 427 (1940)
various:
41, 2266 (1949),
33, 1138 (1941),
38, 251 (1946)
review:
39, 817 (1947)