MW54 Gear Ratio

[Drevil02]

This question is probably for Sara: What is the gear ratio in the reduction transmission from the second stage of the turbine to the vertical output shaft in the MW54? How does the second stage match the first stage in terms of RPM? I am accustomed to seeing curves that show N1 (stage 1) at a certain speed while N2 (stage 2) is always a number lower than N1 since it is driven by the gas generator section. However, as N1 RPM increase the difference between N1 and N2 RPM narrows.

[Bell Bloke]

The gear ratio is 95-1 roughly since it is a 'fluid' coupling and not fixed, and yes as the rpm of N1 increases you would expect the disparity between the two to be less.
I think this is what you are asking?
Hope this helps, all the best Bell :-)

[helibeli]

Say you wanted to fix your main rotor to 1200 rpm with two different helicopters, one weighs 15kg and the other 25kg.What would be the difference in main engine rpm between the two.Is it always the case of useing a tacho on the head and adjusting the throttle in each case?

[Bell Bloke]

Yes that is correct, the final rpm varies depending on the load. ;-)

[Sara]

Thanks for that, Bell! I couldn't have answered it without some technical advice from the guys here.

Sara Parish
Wren Turbines

[Peter Wales]

Yes that is correct, the final rpm varies depending on the load. ;-)

AH HA. Just as I thought. It needs a governor!!!!:)

[Bhavik]

:)

[cbergen]

LOL Peter!! :):)

[Peter Wales]

Got him, and I will have that quote committed to memory and remind him of it at every opportunity :) :)

Happy Days

[Coolice]

Que Sara to bring order to the classroom and sit the trouble makers on the naughty step! ;-)
.

[Matt Jenner]

Just as I thought. It needs a governor!!!!

Sorry to burst your bubble Mr Wales :):)

But it would have to be a governer that works :YeaBaby:

My curve - non governed varies 35RPM on hard climb outs and varying pitch commands on both the Predator and Zealous, i did the same on my jetcat - acrobatic SPH5 and Hotcat PHT3, it varied 150rpm on the SPH5 and fluctuated between 150- 350rpm on the PHT3 :YeaBaby::YeaBaby: the stats showed an overspeeding of turbine rpm on both turbines..

Whats the point of one, if it doesnt work :arggg:

as a popular alcohol Advert goes with editted comments, "Wren dont do governers,but if they did it probably would be the best governer in the world" hee hee ( taken from the Carlsberge advert)

Glad to see you still have your sense of humour though, hope you are well...

And hope your PHT2 project is coming along fine.

it is wet and windy here!

Matt

[cbergen]

To answer the first question, I believe the gearing in the gearbox to be 4:1. I have also gone on the assumption of about a 50% loss of RPM between the core engine and the input to the second stage.

For instance. with an RPM of 125,000 (read from the ECU Download), into the second stage is 62,500/4 in the gearbox gets 15,625/9 (which is the ratio we use in the Intrepid Turbine) gets 1736. With the rotors loaded in a hover, brings it further down to the 1650 range with my throttle curve at 54%.

I know these are rough figures but it is accurate to what MY personal helicopter runs at.

[Peter Wales]

Oops, naughty me.

I'm in an excellent mood. I finally got this monster clear coated last night and it's ready for final assembly. Now I get the rest of the day off to play with some other toys while I wait for the clear to go totally rock hard

[Matt Jenner]

Wow

Pete that looks like a full size fuse from that angle!

Envious of the flying weather you have, it is now thundering and raining hard and i am sitting my Summer house - more like an Ark with the current wet weather..rubbing my canopy..

Matt

[Bell Bloke]

Peter you tart! One word.... Slushbox!! Think about it folks.... Slushbox.:thumbup:

[Skiddz]

I'm jealous of the shop space he's got... All I've got is a small corner of the garage.....

[helibeli]

That could be a small electric helicopter in a Cindy house!

[Bell Bloke]

Just had a call from Matt saying that he thought my 'Slushbox' comment was me being rude.
What I was trying to say was that all 2 stage engines even the JC ones behave a bit like slushboxes ie Auto Torque converters.

[Skiddz]

Just had a call from Matt saying that he thought my 'Slushbox' comment was me being rude.
What I was trying to say was that all 2 stage engines even the JC ones behave a bit like slushboxes ie Auto Torque converters.

You are forgiven my son. Say 3 "Hail JetCats" and get a hair cut. :)

[Bell Bloke]

:rolling:rolling:lolol:rolling:rolling

[rappy-60]

AH HA. Just as I thought. It needs a governor!!!!

LOL, peter... how are you going to put that huge scale bird on your damn trolly??

Dale

[Peter Wales]

I dont need to, it comes with its own set of wheels. I'll just grab it by the tail and drag it around.

[Matt Jenner]

Very Nice Peter..

Look forward to seeing a video of it, was this the one that had a jack/Drill in the nose in the early stages of building..to give you some nose weight.

Matt

[cbergen]

I'll just grab it by the tail and drag it around.

Get THAT on video!! :):)

Peter, would it be out of line to ask if you will assist us during the Turbine Seminar and ground school at IRCHA?

[Peter Wales]

I have no doubt someone will get it on video. I'll be too busy dragging :)

Sure, I'll help with ground school or whatever, just grab me by the scruff of the neck and tell me what you need, but preferably not while I'm flying