Turboprop Questions

[Librarian]

I've noticed that most turboprops have a single exhaust so

Q.1: Why did the Wyvern have two?

Q.2: Could two turboprop engines be mounted centrally piggyback in the fuselage so as to drive a front and rear propeller? If so, would the side mounted intakes have to be asymmetric or could curved ducting compensate?

[Hobbes]

1: probably to avoid having asymmetric thrust.

2. I don't see why not. You'd want the intakes and exhausts to be symmetical, again to avoid asymmetric thrust and drag.
Airplane turboprops usually have the shaft coming out the front, but helicopter turbines routinely have the shaft exiting at the back (through the exhaust), so that shouldn't be a problem. 

[pyro-manic]

A lot of turboprops are actually mounted backwards, so it really doesn't matter.

[Librarian]

Fantastic, many thanks .

[Dizzyfugu]

Didn't the Wyvern have a coupled engine (of two)? Or was that (just) the Gannet?

Concerning a centrally mounted engine, there's still the potential trouble with weight and vibrations. A shaft that runs two props at both ends would certainly have to be massive, weigh a lot in itself and the structure must be rigig (= heavy) enough to carry the thing. And such long, rotationg things are prone to vibrations/oscillation - and I have no idea how much worse this can get when you have an axis though a complete airframe, with props on both ends. I'd be sceptical... 

But, after all, it's whifworld!

[kitnut617]

Didn't the Wyvern have a coupled engine (of two)?

No---  just one very big engine. Which while being a reverse flow turboprop, the drive shaft didn't protrude though the exhaust, as that did exit out the back.

[PR19_Kit]

The Gannet's Double Mamba had an exhaust each, which resulted in a pipe on each side, but maybe such weirdness doesn't count? 

As an example of just how powerful the Python was, it was rated at 4100 bhp, whereas the Double Mamba put out 2900 and the R R Dart managed 1600 at best. Even the more modern Allison T-56, as used in the C-130, only just matched the Python's output.

[rickshaw]

RDa.10/1
    3,245 hp (2,419.80 kW) estimated power at 15,000 rpm, with Water/Methanol injection for the Hawker-Siddeley HS.748MF Andover C Mk.1.

Source

The Big Boys and Girls Book of World Knowledge lists quite a few variants for the Rolls Royce Dart, Kit, many without any notation as to power output but thats the largest one they list.

[PR19_Kit]

RDa.10/1
    3,245 hp (2,419.80 kW) estimated power at 15,000 rpm, with Water/Methanol injection for the Hawker-Siddeley HS.748MF Andover C Mk.1.

Source

The Big Boys and Girls Book of World Knowledge lists quite a few variants for the Rolls Royce Dart, Kit, many without any notation as to power output but thats the largest one they list.

Sure, but that was a developed version and a lot later than the Python's period, which was designed in the 40s.

[zenrat]

Interesting.
The Python Wikipedia page says that a Lanc  and a Lincoln had the outer Merlins replaced with Pythons for testing and that another Lincoln had the same thing done to enable it to fly high enough to drop Blue Danube casings at Woomera.

[kitnut617]

Interesting.
The Python Wikipedia page says that a Lanc  and a Lincoln had the outer Merlins replaced with Pythons for testing and that another Lincoln had the same thing done to enable it to fly high enough to drop Blue Danube casings at Woomera.

Yep! it's what I'm doing here, only this is with the earlier cowling/air intake it used

[zenrat]

Looks good.  I'd probably have just glued a Wyvern fuselage under each wing.

[kitnut617]

Well I did use an aircraft fuselage, can you guess which one I used

[sandiego89]

Well I did use an aircraft fuselage, can you guess which one I used

I guessed Attacker, but then I looked up the serial number...

[kitnut617]

Well I did use an aircraft fuselage, can you guess which one I used

I guessed Attacker, but then I looked up the serial number...