Yamaha RX1 Engines

451 posts in this topic

Posted

Got the RX-1 fired up last night now I'm getting excited. Has anyone tapped into the oil pressure test port on the head and if so what oil pressure are you reading?

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Posted (edited)

You really have an outstanding accomplishment.

You mentioned the oil test port.  A spring loaded check valve and auxiliary/prelube oil pump may be able to hook directly into the oil pressure test port.

Since the RX-1 is a pressurized oil system, I wonder if its TBO would benefit from a pre-lube pump and maybe even a pre-heater incorporated into the pre-lube system?   This could additionally provide a convenient means of having a light weight cabin heater system.

http://turbowerx.com/Scavenge_Pumps/Exa-Pump/Exa-Pump.html

Since the RX1 was made to be a vertical motorcycle engine, I would imagine the oil pickup would lose oil pickup supply during negative G's, climbing, slipping, and (if considered) inverted operations.

I would guess that Winter and daily starting, as well as starting after long times between starting, would benefit from pre-lube and pre-heat.

 

exa-pump-with-new-heatsink_trimmed-2[1].jpg

Edited by JimD

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Posted (edited)

Not sure of the negative G's, but cold weather starts, I envision, should not be an issue, as these are sled engines.  I had one and it would fire up easily, even at -10F.  Quite incredible for a 4 stroke.

Edited by LSaupe

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Posted

Here is a picture of the  engine mount glen (flyingwrench) makes and has for sale.

20170426_194001.jpg

how can we get ahold of the flying wrench? 

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Posted

Glen David (AKA flying wrench)

(623) 256-4115

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Posted

Was there any mention of what this motor mount costs?  JImChuk

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Posted

I would agree that the pump is a nice little ad-on but would rather be able to monitor oil pressure. On a different subject what is everyone using for a tractor prop diameter and pitch?  I have limited ground clearance in my Zenair CH701

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Posted

First start up.  It fired right up.... after I opened the fuel valve.

20170706_215731.mp4

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Posted

Are you running a clutch on there?

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Posted

Yes, rk 400

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Posted

First start up.  It fired right up....    20170706_215731.mp4

Nice sounding engine.  Nice clean installation as well.
 

I've never been around a plane with a propeller clutch before.  Strange to hear engine running and not see the hub spinning.  I would guess that will improve your glide ratio significantly; among other benefits.

 

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Posted

First start up.  It fired right up....    20170706_215731.mp4

Nice sounding engine.  Nice clean installation as well.
 

I've never been around a plane with a propeller clutch before.  Strange to hear engine running and not see the hub spinning.  I would guess that will improve your glide ratio significantly; among other benefits.

 

I wonder about that too.  The 912 that I flew was a brick at idle.  

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Posted

Does the prop then windmill on a glide with engine at idle (or shut down)?

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Posted

Amazing how there seems to be no shake or any movement on the engine.   Could believe someone else was running a different engine in the background.  I think Leni said that the windmilling prop caused tons of drag on his Avid when he was running a clutch on it.  JImChuk

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Posted (edited)

Amazing how there seems to be no shake or any movement on the engine.   Could believe someone else was running a different engine in the background.  I think Leni said that the windmilling prop caused tons of drag on his Avid when he was running a clutch on it.  JImChuk

Increased drag from a windmilling prop was counter intuitive for me.  So I did a search, and sure enough the induced drag is far more than the sail area drag.

https://forums.jetcareers.com/threads/windmilling-vs-stationary-prop-drag.37467/

A feathered variable pitch prop has reduced drag because the pitch is taken out (no rotation) and also has reduced sail area.  So the clutch should stay engaged during an engine out emergency.

Overspeed of prop or mechanicals ignored for the moment.

is this then an effective "speed brake" allowing for a quick change in altitude without gaining air speed?

Scenarios
Losing altitude on approach after clearing a mountain ridge line.

Clearing an obstacle at the end of a runway.

Descending from cruising altitude

... other scenarios?

Edited by JimD

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Posted (edited)

Amazing how there seems to be no shake or any movement on the engine.   Could believe someone else was running a different engine in the background.  I think Leni said that the windmilling prop caused tons of drag on his Avid when he was running a clutch on it.  JImChuk

Increased drag from a windmilling prop was counter intuitive for me.  So I did a search, and sure enough the induced drag is far more than the sail area drag.

https://forums.jetcareers.com/threads/windmilling-vs-stationary-prop-drag.37467/

A feathered variable pitch prop has reduced drag because the pitch is taken out (no rotation) and also has reduced sail area.  So the clutch should stay engaged during an engine out emergency.

Overspeed of prop or mechanicals ignored for the moment.

is this then an effective "speed brake" allowing for a quick change in altitude without gaining air speed?

Scenarios
Losing altitude on approach after clearing a mountain ridge line.

Clearing an obstacle at the end of a runway.

Descending from cruising altitude

... other scenarios?

It wont matter much if the engine quits - You are going down fast in order to maintain flying speed!    If you try to stretch your glidepath in one of these planes you are going to stall it.   EDMO

Edited by EDMO

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Posted

I didn't mean a speed brake with engine out.  I meant during normal operations, would an intentional control of a free-wheeling prop make a good speed brake to provide added control of the aircraft?

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Posted

I didn't mean a speed brake with engine out.  I meant during normal operations, would an intentional control of a free-wheeling prop make a good speed brake to provide added control of the aircraft?

Wont matter much - Remember the Ed Downs quote:  "It's like comparing a Badminton Birdie to a Tennis Ball" - EDMO

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Posted (edited)

It wont matter much if the engine quits - You are going down fast in order to maintain flying speed!    If you try to stretch your glidepath in one of these planes you are going to stall it.   EDMO

Kitfox glide ratio not as good as I thought, but better than average.  Even though I read a post where a pilot was riding thermals with his Kitfox.  Though I don't recall if he was maintaining altitude.

Kitfox: 7.8 (at Vg of 60 mph that is 677 fpm sink rate)
Lancair IVP/Legacy: 13

Glasair III short/long tips: 6.7 /7.1
Questair Venture: 10.5
Cirrus SR22: 10.3
Super Cub 6.9
C 172: 7.3
Zenith CH 801: 3.6
Dehavilland Beaver: 9.2

Twin Otter: 10.1
Caribou: 10.0
Pilatus Porter: 8.8
Quest Kodiak: 8.4
Britten Norman Islander: 7.4
8GCBC Scout: 7.3
Westland Lysander: 9.6
Short Skyvan: 11.1
PAC 750 XL: 6.6
Dornier Do 27: 7.4
Antonov An-2: 8.3 (approx., each wing)
Sportsman 2+2: 9.1

Edited by JimD

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Posted (edited)

It wont matter much if the engine quits - You are going down fast in order to maintain flying speed!    If you try to stretch your glidepath in one of these planes you are going to stall it.   EDMO

Everything I've been reading indicates that a Kitfox has an excellent glide ratio.  I even read a post where a pilot was riding thermals with his Kitfox.

I cant say about the newer (Kitfox 4 and later) wings with the Riblett airfoil, but the older undercambered wings fly like a parachute!   There isn't enough weight / kinetic energy to overcome drag.  Your only control is throttle and stick.  EDMO

Edited by EDMO

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Posted

Short of raising or lowering your RPMs, I don't think there is a way to engage or disengage the clutch.  I've never used one, but maybe Leni will pipe up on the drag from the clutch/prop  combo.  JImChuk

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Posted (edited)

She's getting real close now......

 

Edited by Copro

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Posted (edited)

She's getting real close now......

 

Never have seen a video that was only 1/2" tall..... ???  Well, looks like there is a full view too!   EDMO

Edited by EDMO

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Posted

She's getting real close now......

 

I was waiting for ya to tow that red truck into the garage!

;)

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Posted

Little late to the party but I will toss in my learned knowledge.  I LOVE the clutch.  Start ups, idle and shut downs as well as warm up is OH SO SMOOTH!  The down side.. when you have an engine out, you do have the glide much like a greased anvil!  It is nice if you are one of those guys that likes to stay at pattern altitude till you turn short final then float down the runway past the end.  If you pull the power back and let the prop free wheel you can just about peg the VSI at 50 MPH.  The sink is something to behold. 

The down side to it other than sink is that if your starter of battery goes out dead on you in a remote location, you don't have a chinamans chance to prop it.  I tried to figure out a way around it but short of having the GPL starter system with recoil back up you are pretty much hosed.

:BC:

 

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