C172 ENTERS CLASS D AIRSPACE WITHOUT CLRNC WHILE AVOIDING CLASS C AIRSPACE NEAR VNY.

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I WAS PLTING OUR C172 WITH MY WIFE AS PAX FROM POC TOWARD LGB; AROUND THE PV PENINSULA; OVER LAX VIA THE SFRA AT 4500 FT MSL. I HAD INTENDED TO CLB TO 5500 FT MSL AFTER OUTSIDE THE LAX CLASS B AIRSPACE. INSTEAD; I ASKED MY WIFE IF SHE'D LIKE TO STOP AT WHP IF THEY HAD 80 OCTANE FUEL. CALLED WHP TWR WHILE W OF BUR CLASS C AIRSPACE OVER WOODLAND HILLS. TWR AFFIRMED 80 OCTANE AVAILABLE. TOLD WHP TWR I'D CALL LATER FOR LNDG. SKIRTED BUR CLASS C AIRSPACE WHILE DSNDING. WHEN BELOW THE 3000 FT MSL FLOOR OF CLASS C AIRSPACE; FOLLOWED 118 FREEWAY E. I DID NOT NOTICE THE NORTHERN EDGE OF THE VNY CLASS D AIRSPACE ON MY LOS ANGELES TCA CHART. JUST ABOUT AT THE INTXN OF THE 118 FREEWAY AND VNY CLASS D BOUNDARY (VNY 320 DEG RADIAL); I CALLED WHP TWR FOR LNDG. THE TWR OPERATOR INSTRUCTED ME TO CONTINUE FOLLOWING THE 118 FREEWAY. I DID. WHEN TAXIING FOR TKOF; WHP GND ASKED IF WHP TWR HAD TALKED TO ME ABOUT VNY INCURSION. NEGATIVE. GND THEN TOLD ME VNY HAD TOLD WHP I WAS IN VNY AIRSPACE. IF I DECIDE AGAIN TO DEVIATE FROM MY ORIGINAL INTENDED FLT; I WILL CIRCLE AND STUDY CHART FOR OBSTACLES.