According to Red Army Tanks of World War II the British & Canadians sent 5,193 tanks (of which 4,483 actually arrived) and US tanks sent as Lend-Lease totalled 1,682 light (1,239 arrived) & 5,374 mediums (4,957 arrived).
Except the time it would take to retool US factories to build Soviet equipment and spare parts could mean that the Soviets are defeated before any deliveries are made.
Very true that the timing of the Aid to the Soviets is key
and the period of maximum danger is (iOTL at least ) from July 41 to Dec 42.
However in this period,
American Material was not a significant factor in avoiding a Soviet defeat.
America did begin considering aiding the USSR quite quickly after Barbarossa started
but started slowly by first allowing outright purchases (which the Soviets could barely afford)
then extending limited credit facilities (which did allow some deals)
and only added Russia to the Lend part of Aid in November 41.
However, after Pearl Harbor, all plans were scrapped for the time being.
In fact, much of the Material bought was redirected to equipping the forces America was urgently raising!
For the first 12 months, aid to Russia came almost entirely from Britain and its Empire delivered from Late summer 41.
It was at all levels - tanks, planes, raw materials even some machine tools.
Most manufactured items were made in Britain (like Hurricanes)
though some were American built materials (like P-40 models) that had been bought for British or allied use but redirected by Britain to the Soviets.
In terms of the eventual volume delivered, this initial surge was quite small and of lower grade kit
but it was at a vital time following huge losses and before Russia's own production, especially the factories relocated in the wake of Barbarossa,
could deliver the better Russian designs (like the T-34) , at least not in the required quantity and by most reports quality was awful
It was only in 1943 when the production lines in the USA were really rolling that Russia got priority
particularly for base materials and logistics vehicles like lorries etc.
IMHO it is fair to say that British Aid to Russia was more responsible for avoiding the USSR's defeat in 1941 and 1942
while Russia's own production allowed them to hold the line in 1943
and American Aid to Russia was a significant part in ensuring their victories in 1944 & 45
I used to have access to quite a detailed paper on how important British tanks and planes were in the period Nov 41 to Nov 42 but lost it when I retired.
The best I can do now is this article which touches on the highlights
The Soviets have long insisted that Lend-Lease aid made little difference. Newly discovered files tell another story.
www.historynet.com
basically, 30% plus of the medium/Heavy tanks defending Moscow in the winter 41-2 were British supplied
as were 15% of the effective fighters plus others covering the vital Northern ports
Note: this is a direct copy of material I have posted before on other threads that underrate the importance of British aid to the USSR
www.thedrinksbusiness.com
