Brantly 305

[seneca2e]

An intriguing machine that never got sorted out completely. How many were built and did any ever fly successfully? I know Jerry Toms had ideas of how to fix this machine but have forgot what actually its problems were. If the new company could get it on the market for a great price it could carve out a market overnight.

[N2285U]

I think it had a tendancy to sling main and tail rotor blades. If you think the B2B is loud, how loud would a 315 HP IO-540 be with no exhaust?

[SunHelo Paul]

The NTSB reports 25 accidents/incidents involving the Brantly 305. Five were fatal with nine fatalities altogether.

Nearly all were as a result of pilot error.

Seven involved mechanical failure:

One engine 'flame out'.

Three tail rotor failures all caused by fatigue cracks either in the gear box or the blades themselves. I believe adequate maintenance and inspection should have prevented these.

Three main rotor failures, again caused by fatigue cracks and preventable with proper maintenance and inspection.

There does not appear to be anything fundamentally wrong with the design.

[N2285U]

Paul - I originally was going to convert a 305 to a turbine years ago as a project and talked to some people that actually flew the 305. They said that the main rotor system developed cracks continuously and was extremely hard to keep in balance & track as well. They also had tail rotor problems on almost a per-flight basis. Yes, you could call it "pilot error" by saying good maintenenance and preflight would have prevented the problem; however, repairing the helicopter every 10 hours is not reasonable and that is why the 305 never made it in the certified world. Rotorway can get away with it with their HORRIBLE secondary drive system since many owners think they can design or use another drivetrain and make the helicopter safe, which also turns out to be a mistake.

[SunHelo Paul]

A turbine conversion for the 305 is an idea that has appealed to me as well; however, your experience suggests that a little more investigation of the design might be a good idea first.

[N2285U]

I figured a C20B would fit nicely and would give you all the power you needed.

From what I understood many of the problems stemmed around the dampener attach points and cracking around the rivits. I know the dampener attach points were always a concern when removing blades on my B2B. You want to be very careful about not "knicking" the skin. Also, improperly adjusted/torqued dampener bolts will cause the attach holes to become oblong. I always thought the blades should have steel or brass replaceable bushings in these holes or that section should be more rugged.

[Al Owen]

Innodyn is producing a line of Turbines that would be a very good choice for the 305 conversion. The cost is comparable to what you would have to pay for an IO-540 or similiar engine and far less than a C20 ... There are several already being used in Experimental fixed wing such as Van's RV-4/6 and flight testing in a helicopter is also underway ..

Web-site: http://www.innodyn.com/aviation/products.html

[N2285U]

Al,

That engine will NEVER do what Innodyn says it will. I had one on order in April 2005 for December 2005 delivery. Of course it never happened. For years I have asked them to hook the engine to a simple dyno and run the engine for an hour to confirm fuel flow and horsepower claims. Guess what? They would not do it because they know it burns about 22 GPH making about 150HP. It is a single stage compressor and adding PWM fuel injection will not help efficiency at all. They will have a hard time ever getting BFSC under .85 and that is only going to happen with a newly designed compressor wheel. Right now BFSC is about 1.2 which equals 1.2 lbs of fuel per horsepower per hour = 45 GPH IF the engine could make the 255 HP it claims which is still not enough. The helicycle uses the same basic engine and burns about 13 GPH using roughly 95 HP.

The Allison C18/C20 series use a multistage compressor and can achieve BFSC close to .7 which gives a helicopter using the engine a fuel usage of roughly 22 GPH +- depending on use.

The real winner will be if the turbo diesels ever become mainstream and can be integrated into a helicopter. There are considerations of damaging vibration that would have to be dealt with though.

[Al Owen]

Their web-site makes it sound pretty convincing but they don't give much on the technical side other than the 7 gph per 100hp figure.... If it's not any better than the Solar turbines, they are wasting a lot of effort and money...

There is a diesel helicopter project "down under" using the DeltaHawk engine that looks promising, but time will tell..It's on the RotorWay Owners Group web-site. I had a chance to look over the diesel twin fixedwing from Europe last year at Sun-N-Fun.. They have apparently not been as good as advertised either..

[seneca2e]

Sheesh all the blade cracking and problems with the 305 makes you wonder. It seems there's been a pretty large number of blade cracks even in the B2Bs-especially considering these things don't get flown that much.

[N2285U]

Their web-site makes it sound pretty convincing but they don't give much on the technical side other than the 7 gph per 100hp figure.... If it's not any better than the Solar turbines, they are wasting a lot of effort and money...

There is a diesel helicopter project "down under" using the DeltaHawk engine that looks promising, but time will tell..It's on the RotorWay Owners Group web-site. I had a chance to look over the diesel twin fixedwing from Europe last year at Sun-N-Fun.. They have apparently not been as good as advertised either..

The problem is they have NEVER measured horsepower with any known measuring tools. They have computed HP from the airspeed of the RV-4 they have been flying and have then filled the tanks back up to see how much fuel was used. Their engine is a copy of the Solar turbine and that is a single-stage centrifical compessor. It makes a great GPU, but is not efficient enough to ever be usable in anything flying with more than 1000 Gross weight or so and at altitude it will have decreasing power just like a piston engine. It takes a multistage compressor to produce efficiency and power. PWM does nothing for a single stage compressor. The helicycle can get away with it since they are only putting in one occupant and are only using 95 HP, but it still burns 13+ GPH which is not real efficient when JETA is $5.

[Al Owen]

I'll be at Sun-N-Fun all week volunteering at ChopperTown, but I'll take a good look around and see if Innodyn shows to display their stuff...
I might be fun to bring this up again and see what kind of answers they have now..

[Earl of Rochester]

Does anyone know if there are any airworthy 305's and, if so, how many and where?

Earl

[Brad Bowles]

1 Gary Goldsberry has a the only flyable 305 nice ship. Not sure the last time it flew. He has a 2nd 305 I think has enough parts to fly again also. Talk to Harold and Gary they can give you details on the 305.
Brad

[Earl of Rochester]

Thank you Brad

Is Gary's the only airworthy ship in the world and is it based in the US?

Is Gary a member of Brantly Info?

Earl