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New Honda Radial Engine

FresnoR

FresnoR

Well Known Member
Ok, so its a custom build for an airboat using Honda XR600 top ends, but probably one of the coolest things I have ever seen. Just stunning:

xr600-radial-gears.jpg

xr600-radial-gears-2.jpg

xr600-radial-master-link-rods.jpg

xr600-radial-exhaust-ring.jpg


http://thekneeslider.com/archives/2010/04/22/honda-xr600-9-cylinder-radial-engine-progress-continues/
 
I liked the naked Rotec Radial on the Helve Classic (sp?) but an RV begs for a full cowl, as per WWII fighters, Pre War racers etc. Well, that's where my Walter Mitty resides ;)
I wonder what the diameter of this Honda derived engine is? Sure looks like fine workmanship!
I'm also struck by the look of the RV-3 with the LOM inverted 4, and the James Cowl for rotary engines.
Face it, RV's look great no matter how you dress them up!
 
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Rotec-engined motorcycles

I was surprised to find two Rotec-engined motorcycle designs while surfing various various sites.

This one's linked from the Rotec website and has a transverse mounted engine (like most motorcycles) JRL motorcycles video

Here's one with a fore-aft mounted engine (like an airplane). It's supposed to have been built by Jesse James and is truly wild-looking
 
Those gears are going to take a beating; alternately driving and driven.
Bet the TBO is pretty short.
 
Indeed. Having been inside a lot of XR, there is probably a small sprocket on the backside of each of those gears to turn the timing chain that goes to the overhead camshaft(s). Usually the small sprocket is on the end of the crankshaft and the large gear turns the clutch assembly.
 
I hope the gears last!

I have a neighbor who built a 5 cylinder engine using poulan chainsaw engines. He didn't use a master rod setup like that, but used gears like the picture shows.

The engine sounded neat when it ran, and he even built a fuel injection system for it because he didn't like the way the carbs made it run. He also made an ignition system to use smart plugs (kind of like a glow plug).

http://www.smartplugs.com/index.html

After all the work, the gears wiped themselves out in about an hours worth of run time.:(

Now it hangs on the wall in his shop.

I hope he gets it to work, but the gears worry me.
 
lancef53 said:
I have a neighbor who built a 5 cylinder engine using poulan chainsaw engines. He didn't use a master rod setup like that, but used gears like the picture shows...
Click to expand...

Again, I'm pretty sure that the nine little gears are the drives for the chains that in turn drive the camshafts in each cylinder head. Even with four valves per cylinder those gears are pretty lightly loaded and look to be plenty beefy enough for the job.

I believe that the crankshaft is driven by the pistons through a typical radial setup where there's a single master rod between the crank journal and one piston, and smaller rods for all of the other pistons. To me, those parts look plenty beefy too.

Thanks, Bob K.
 
I understand that the gears are for the timing, I was just relaying some info. It will be really tough to set the backlash on that many straight cut gears, and have it work both cold and warm. The pulses tore my friends apart.

I hope it works well, It will be neat to see run.

Edit--It says in the 2 links that he is using a planetary setup for the prop drive, to get the RPM for the prop correct. It also said the cam drive setup involved 12 gears on 3 planes--there must be a couple more gears hiding behind that cluster.

I wonder where the chain drives for the cams fit in? Or do the xr 600's have a chain drive cam?
 
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Dave:
I agree about a boat for the real world dynomometer.
All the load control you could ask for, in an environment that you can control, possibly even sit beside the engine while it runs to check for leaks and listen for odd sounds, and if it quits, well rowing is not fun, but I recall something about the air being even more unforgiving than the sea...
If it's an airboater that goes out with his buddies....that would be fine!
 
It really violates the KISS priciple...

...with an excessive amount of moving parts. My old Pratt and Whitney 1340 cu. in. engines had a simple circular cam ring, with lobes at appropriate intervals and a direct-drive prop.

I've been told that the Germans copied/improved the engines for their Fokke Wulfs,

Best,
 
The Honda RFVC is pretty complicated in the drive train area. All 4 valves are angled inward like a Dynafocal mount. This requires a pretty tricky rocker setup to transfer the movement from a single cam. What they did was double up the number of rocker arms, and have one rocker arm push the other that in turn pushes the valve. This way the valve rocker and the cam rocker (or follower is probably a better term) can pivot on different planes. Indeed, alot more moving part.
rfvc_head.jpg

rfvc.jpg
 
Radial Engine Development

For an interesting perspective on what is required for development of a reliable radial engine, read the series of PDF articles about the development of the P&W R-2800 called "No Short Days" found near the bottom of this page:

http://www.enginehistory.org/engines.htm

The articles are very interesting and informative. It is absolutely astounding how much time and effort was expended trying to find and solve the complex harmonics that can exist in an engine.

Skylor
RV-8QB Final Assembly
 
Not quite the same

pierre smith said:
...with an excessive amount of moving parts. My old Pratt and Whitney 1340 cu. in. engines had a simple circular cam ring, with lobes at appropriate intervals and a direct-drive prop.

I've been told that the Germans copied/improved the engines for their Fokke Wulfs,

Best,
Click to expand...

Pierre,
Wasn't that old Pratt a pushrod engine? Much easier to drive with a cam ring as you said, but not an overhead cam engine as with the Honda. And yes as you stated it violates the KISS principle.
Bill
 
skylor said:
For an interesting perspective on what is required for development of a reliable radial engine, read the series of PDF articles about the development of the P&W R-2800 called "No Short Days" found near the bottom of this page:

http://www.enginehistory.org/engines.htm

The articles are very interesting and informative. It is absolutely astounding how much time and effort was expended trying to find and solve the complex harmonics that can exist in an engine.
Click to expand...

Thanks for the link regarding the history of the Pratt & Whitney radials. Very interesting!

L.Adamson --- RV6A
 
pierre smith said:
...with an excessive amount of moving parts. My old Pratt and Whitney 1340 cu. in. engines had a simple circular cam ring, with lobes at appropriate intervals and a direct-drive prop.

I've been told that the Germans copied/improved the engines for their Fokke Wulfs,

Best,
Click to expand...

BMW license built the PW (something), improved some things and named it BMW 132, a nine cylinder radial. It was used on the Ju 52 and some other pre-war transport planes.

The BMW 801 used on the Focke Wulf 190 was a 14 cylinder radial (two rows of 7 cylinder). It was based partly on the development done at Bramo. BMW purchased the Bramo company.

Bramo engines, 9 cylinder radial, were used on the Focke Wulf 200 bombers, and lots of others. This engine was developed based on the british Bristol Jupiter.
 
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