Sputnik double

This is a conventional bid for Responder after a 1♦ or 1♥ overcall by Opp
With 5-6HCP and 4 or 5 cards in a major - you have to bid!

Resonder bids a suit one ranked higher than that of the overcalled suit it promises 5 cards in that suit.
With 4 cards in the suit ranked one level higher, Resonder bids X
Bidding the suit ranked above (ex. Spades after a diamond overcall) is ambiguous : Responder can have 4 or 5 cards.

S	W	N	E

Problem E5628 X After a 1♦ overcall, double promises exactly 4 ♥ cards.

S	W	N	E

Problem E5629 1♥ After a 1♦ overcall, bidding 1♥ promises exactly 5 cards (suit ranked one level higher than that of overcalled suit)

Negative Double Consequences

If Responder's bid suit isn't one just ranked above Overcaller's suit, Opener doesn't know if Responder has 4 or 5 cards.
After a diamond overcall, Responder's X promises 4 ♥ cards. Of course, you can't use the X to bid 4 ♠ cards.

S	W	N	E

Problem E5664 1♠ After a 1♦ bid, a 1♠ bid is ambiguous : Responder has 4 or 5 ♠ cards. (suit isn't ranked one level above overcalled suit)

S	W	N	E

Problem E5662 1♠ After a 1♥ overcall, a 1♠ bid promises at least 5 cards (suit ranked just one level above overcalled suit)

Responder's follow on bids after X on a 1♦ overcall
On the following bidding round, Responder can describe his hand :

after doubling, if he bids the suit which is ranked one level higher than overcalled suit, he promises 4 cards in the other major (♠) and a hand with no Game ambition. He can't have 5♥ cards, otherwise he would have bid them in the 1st round!
If he bids the other major in the next round, it means he also has 4 ♠ cards and a hand to go for Game

Exercise 20223 2♠ shows 4 cards and 4 cards ♥ in a game forcing hand (12HCP or more ...)

Problem E20224 after doubling the 1♦ overcall, 2♥ shows 4 ♥ cards and 4 ♠ cards in a hand with no Game ambition.