Callum Black is named at loosehead prop as he continues his efforts to return to the senior squad following a neck injury earlier in the season.
He is joined in the front row by experienced hooker Nigel Brady and 22-year-old Development prop Adam Macklin. Neil McComb will partner Tim Barker in the second row, while Ali Birch, Mike McComish and Robbie Diack combine in a dynamic back row.
Ballymena's Blane McIlroy and Dungannon ace Paddy Jackson will form the half-back pairing, with Phoenix Academy player Chris Farrell partnering the experienced Ian Whitten in the centre.
Academy trio Chris Cochrane, Michael Allen and Peter Nelson, who have been in impressive form in the Ulster Bank League, will make up an exciting back-three.
Two familiar faces will return to Ulster in the shape of Doncaster full-back David McIlwaine and flanker David Bradford, who both left the province in the summer. The Knights have three other Irish players in their matchday squad - prop Royce Burke Flynn, number 8 Michael Noone and reserve back rower Zack Farivarz.
Longwell is glad to be able to call on a few experienced names, stating: "We have been training well and the combinations are looking sharp.
"Having that sort of quality in our pack will hopefully provide our youthful back-line with a good platform to launch off. We expect Doncaster to be physical up front and we know they have the ability to hurt us if we don't play to our potential."
ULSTER RAVENS (v Doncaster Knights): Peter Nelson; Michael Allen, Ian Whitten, Chris Farrell, Chris Cochrane; Paddy Jackson, Blane McIlroy; Callum Black, Nigel Brady, Adam Macklin, Tim Barker, Neil McComb, Ali Birch, Mike McComish, Robbie Diack.
Replacements: Niall Annett, Conor Carey, James Simpson, Sean O'Connell, Michael Heaney, James McKinney, Ricky Andrew.