United's U18s made it eight consecutive league victories with a hard fought success against Championship opposition in the capital at the weekend.
Jordan Hallam's 18th goal of the season from the penalty spot in the first-half was enough to defeat the R's as Travis Binnion's side set a new club record in the modern era with this win.
United started brightly and forced an early corner, from which Semple fired over, then from Hallam's inswinging free-kick, the young centre-half was flagged offside with the goal at his mercy.
Tyler Smith then combined with Hallam, but wasted the subsequent opportunity, before Hallam was bundled over in the box, but no penalty was awarded. At the other end, the home side should have gone in front in the 23rd minute, but from point blank range the header was straight at the grateful Ramsdale.
And that missed proved costly for Rangers, who found themselves behind three minutes later. Brown saw his headed saved from Gilmour's cross and a retreating R's defender could only foul Hall, who had reacted first to the rebound. HALLAM confidently stepped up to fire home the resulting spot-kick to put the Blades in the ascendency.
The remained of the first-half petered out with little in the way of goalmouth action, although who was the visitors who enjoyed plenty of possession.
United were also quickly out of the blocks after the interval, with Tyler Smith and Hallam again having opportunities in the opening five minutes of the second period.
But in the final half hour it was QPR who really probed and pushed in search of an equaliser, but the Blades defended resolutely as a team and made all three changes in quick succession in a bid to see the game out.
In the end the R's were restricted to a few set-pieces and a couple of long-range efforts as
United held on for another deserved win and a second consecutive clean sheet on the road as they home in on a top two finish.
Blades: Ramsdale, Cummings, Brown, Gilmour, Adebowale, Semple, T. Smith (Gordon 79), Ford, Hall (Litchfield 69), Hallam, K. Smith (Mallon 63).
Unused: Maw, Warhurst.