Fei Bao Dolphin Setup
 

I have a few questions for current owners of this jet or anyone who has assembled one previously.

I am currently at the stage where I need to install the engine (Jetcat Titan). The supplied pipe has a very large bowl shaped bellmouth. My question is how far forward of the foremost lip of this bellmouth can the trailing edge of the exhaust cone be.

Right now, without grinding away the aft end of the intake (so the engine can be mounted further forward), the edge of the exhaust is roughly even with the forward edge of the bellmouth. Bellmouth diameter at the forward edge is 5.75" (about an inch larger in diameter than the engine); 3.5" where it fastens to the pipe, and is 2.75" deep. The bellmouth reminds me of the aft end of a carbon fiber bypass for an engine of this size.

I would like to mount the engine further forward to assist in balancing this beast! So, what has your experience been?

You can do a search for proper exhaust to pipe distance, but generally the end of the tailcone is about 3/4 of an inch away from the beginning of the straight part of the pipe. Forget that the bellmouth even exists and it will make more sense.

I've had this diagram for years, hope it helps.

Steve,

Secret Agent is correct. . .3/4" from nozzle (cone) to entrance of the pipe (not bell mouth) is the correct positioning. As for balancing, we have sold many Dolphin and Dolphin S to our customers in the US. Some have purchased both and some have purchased two of the same model. You need not be concerned about cutting intake etc; as balancing has never been an issue. With both batteries (Rx) aside the nose gear (we offer a custom laser cut wood kit) and all equipment installed, UAT full of fuel you then can place the ECU battery for correct balance. If you are using a smoke system, place the smoke battery on the CG. The CG and control settings as listed in the manual written by our friend Rich Miller, are spot on for the maiden flight. You can then adjust CG from there to suit your needs. Get all the flap you can as the Dolphin is "light on the wing" and floats. Give me a shout if you need anything or have additional questions.

Rgds,
Eric Clapp
A & E Jets USA
formally jet central usa
FeiBao Jets USA
941-468-1246

OK. I am aware of the 3/4 inch rule of thumb that you guys have pointed out in the replies above. I was just wondering if the unusually large bowl shaped bellmouth made any difference. Apparently not so the engine will be mounted 3/4 inches from the entrance to the pipe.

Steve. . .FB Jets supplied bellmouth is designed to collect and get as much air into the pipe as possible for cooling. A high pressure area is created directly proportionate to thrust being produced. This high pressure area is necessary to cool the pipe and move as much air as possible through it. The same effect may be experienced in a full bypass install. With turbine running, try to remove the bypass cover (top). You will feel suction. Once removed, the rpm of the turbine will actually increase on its own. . .because it now has no restrictions to the high pressure area around nozzle. The bellmouth also will aid in containment of flame should a hot start occur.

Eric

Hi Steve. I PM 'd my ph to you. Call me tonight and I can discuss the finer points of Dolphin setup. I have had 2 and love them! Great flying jet. With a 180 size motor I would go with 1" from motor to beginning of PIPE.