Small Aircraft
Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 50; Flight Crew Total 2600; Flight Crew Type 500
Situational Awareness
Airspace Violation All Types; Conflict NMAC
Flight Crew Took Evasive Action
Human Factors; Airspace Structure
I departed Runway 33 from CGS; announcing my departure on Unicom. A helicopter a mile or two from the DER acknowledged my transmission; said that he had me in sight; and I would be 'no factor.' CGS is a short strip just under the Class B airspace; has left traffic; and that left traffic pattern is sandwiched near Joint Base Andrews. I departed Runway 33; turned crosswind and downwind; only to find that the helicopter had entered my flight path. To avoid the helicopter; I moved outside and above his flight path; taking me within a mile or two of Andrews' airspace and violating the Class B shelf by 100 feet or so.In retrospect; I should not have departed until the intentions of the helicopter were clear and the airspace around the airport was clearer. My pressures were:(1) Potomac approach had already issued me a beacon code; and graciously asked if I could possibly depart VFR and stay clear of the Class B before joining the IFR system en route to [my destination.] (2) The taxiway was closed for repairs; requiring airplanes to back taxi on the runway to get to the beginning of the runway; so there was no safe place to sit and figure out what the helicopter was going to do. I was on the (active) runway with no easy place to taxi off and wait it out. So I launched -- knowing and seeing the helicopter -- but not knowing precisely what the helicopter was going to do. And given that CGS is a small strip; I do not think the helicopter was expecting the speed of closure and the rate of climb that [this small; turbocharged aircraft] produces--in excess of 1000 fpm at 125 kts. I did what I needed to do to see-and-avoid as required under VFR. However; in so doing I came near Andrews airspace and got up to 1600 MSL when the floor of the Class B there is 1500 MSL. At the same time; I was trying to reach Potomac Approach for permission to enter the Class B. In retrospect; I should have taxied back along the runway; cleared at the only open turnoff at midfield; and waited until ATC could clear the airspace and allow me to depart IFR.
GA pilot reported entering Class B airspace while maneuvering to avoid a helicopter shortly after takeoff.