Hand Made Bentley BR2 Rotary Engine

Hand made, scratch built, scale working WWI Bentley BR2 rotary aircraft engine. I filmed this in York PA in 2004.

Update: If you guys want, I'll try to post stills I took of this engine. If there's interest, I'll post them.

Category:

Howto & Style

Tags:

• R/C
• Bentley
• BR2
• Gnome
• aircraft
• engine
• radial

[myConscious]

QUESTIONS:

1. Does the cylinders & the propeller both rotate in the same direction?

2. If they do, what if, the cylinder portion of the engine & the prop were very close to equal in weight and they rotated in OPPOSITE DIRECTIONS to each other, would that not reduce (cancel out the opposing forces) the undesirable "one sided" gyroscopic effect?

Thanks

[Error4O1]

@myConscious The prop is bolted to the casing and cylinders and rotate together. Making a transmission to get the prop to go opposite the cylinders would add weight and complexity, and thus introducing more potential failure points as well as offsetting any benefit by reducing power to weight ratio.

The first thing you have to remember is this design was from the early 1900's, And secondly, it had pretty much reached it's pinnacle in design by the end of WWI (1918-ish)

[GREEVES246]

@Error4O1 there very complex i have a the drawings for it if you made it it must be a

labour of love

have you ever seen the way they used to start these things ! funny thing they have a ford model T and retro fit a shaft with drive from the back axle with 2 spades to engauge the prop and there were mag settings to ajust the throttle !

[Error4O1]

@GREEVES246 Wasn't my engine. I was just a spectator at the event. cfmeq (YT user) was the builder of this engine, and credit has to go to him for the work done.

Yeah, that old-school tech was kind of scary sometimes (I guess it was pre OSHA). I do fly R/C, and sometimes you have to start the models old school too.

[chopperdanny13]

Another problem with this type, as alluded to and causing the ultimate demise of this type of engine is gyroscopic precession. Planes with these could turn faster one way than the other. If a pilot stalled, often a violent spin would result. With so much rotating mass changing directions was difficult. Google gyroscopic precession to learn more.

[chopperdanny13]

Beautifully made engine. To those that still dont' get it, it is a Rotary engine with the cylinders arranged Radially around the crankshaft. The crankshaft is fixed to the rest of the fuselage, or test stand in this case, while the engine, connected directly to the propeller, spins around it. One of the main problems was that there was no way to control the throttle. The engine ran either full on or full off, with pilots shutting off the magnetos to regulate rpm. More next comment.

[callmeshane303]

@chopperdanny13

Gyroscopic precession.

There is an easy way to replicate this - get a bicycle front wheel with axle etc., hold the wheel by the axle, and get a friend to spin the wheel as fast as they can, and then try to change the wheel direction i.e. make a hard left or right turn....

[justforever96]

@crash25016 You're thinking "radial"; all rotaries (not Wankels) do this. A radial is a crankcase/cyls bolted down, with a crankshaft spinning inside, connected to the prop. A rotary is a crankshaft bolted down, with the case/cyls rotating around it, the prop bolted to the case. In terms of valve-train and pistons, they're the same, only reversed. The oil is mixed with the fuel like a 2-stroke; fuel/oil/air drawn thru the crnkshaft/case, into tubes to the valves; it's all burned up: "total loss"

[jradetzky]

does it fly?

[TheRealFobican]

LOL the author has a common error´s name! XD

[crash25016]

never saw a rotary engine with the cylinders rotate with the prop... how dosnt the oil force its way into the combustion chamber?

[Poopingbotham]

Very good indeed. If you can build some full size ones, you wouldn't have much problem selling them, what with so many WW1 replica aircraft flying with non-authentic looking engines.

[yashypandya]

i am with you



[MartinOhrndorf]

Your engine is amazing, congratulations!

[schlusselmensch]

@GREEVES246 That was known as a Huck Starter, by the way.