Westland-Fairey Rotocrane HC4

[PR19_Kit]

BIG problem with the rotor............ 

I've almost doubled the fixed wingspan (force of habit....) and the Chinook blades are quite a bit shorter than the 'dyne's normal blades, the rotor just doesn't look big enough. The 'dyne's standard rotor has very high aspect ratio blades and is MILES larger in diameter than the wing span.

I'm wondering if I should use the remaining six Chinook blades to graft an extension into the centre of the Rotocrane's blades. I might try one and see what it looks like..............

[TheChronicOne]

I vote for that option. Sounds like it should be relatively easy to do with some clamps and then a little sanding and now you get to use up those spares. 


Rotor blades of adequate length are definitely a must, I agree!

[Old Wombat]

I vote for that option. Sounds like it should be relatively easy to do with some clamps and then a little sanding and now you get to use up those spares. 


Rotor blades of adequate length are definitely a must, I agree!

Not forgetting the drill, bit & wire for strengthening the join(s).

[PR19_Kit]

You can see exactly what I mean here with this comparison pic. The Chinook blade in the LH pic may have MASSIVE chord, but no span at all really, compared to the original 'dyne blades in the RH pic. That's the Revell 'dyne rotor in the RH pic BTW, so it's slightly undersized anyway.



As I've already glued the Airfix tip jets onto the Chinook blades I've glued the first extension into the centre of the blade, but hindsight tells me it would have been better to cut the tip jets off again, then glue on the extension and then re-glue the jets.

I've taken two of the blades off the hub (VERY carefully...) as I'm certain that they'll all need extending now, but the prototype extended blade has one superglued joint and one styrene glued joint. I'll see which one works best, but I'm not sure about the 'drill and wire' business yet as the blades are only 1.5 mm thick.

We'll see what works, or not..............

[TheChronicOne]

You're really flying by the seat o' your pants, now. 

[PR19_Kit]

The superglued joint works a treat, the styrene one doesn't, so I'll do the rest of the blades with superglue and take the tip jets off first.

Ho hum, we're making SOME progress anyway.

[Runway ? ...]

Just a thought, Mil-10 blades come in a pack of five at 8.5 inches each.
I only have vacform Sanger parts for reference.

[PR19_Kit]

The new, longer blades are all done and dusted now, indeed its a veritable production line of blades here this evening! 

Weirdly the grey Airfix blades glued a lot better than the dark green Italeri blades, but I'll leave them all to set well hard for an hour or so before assembling at least some of them back onto the hub. They may need a tad PSRing beforehand though, my superglue sets VERY hard.

I don't think I've ever PSR'd a rotor blade before. 

[rickshaw]

The real Rotodyne's rotor blades have always struck me as a little odd.  The start about a quarter of their length out of the hub with a bladed structure, inboard of there, it is just a tubular structure.  Now, I'm sure they did for a reason but I really cannot think of one.  They could have shortened the blades by a quarter or they could have filled them in with more blade and hence increased lift.   I wonder if they did it because they couldn't get much lift out of the inner quarter because of the fuselage structure or is it just sheer bloody British mindedness which made them design them that way?   

[TheChronicOne]

Probably the former, in a round about way; there's a lot of body there in the Rotocrane and it's like the ol' helicopter lifting a piece of plywood problem, if the plywood is as wide as the rotors are round, the helicopter won't lift off because the lift generated also is pushing down on the sheet of plywood and they cancel out. I'd suspect that some of that lift being generated toward in the inside was pushing down on the fuselage as much as it was "pulling" up through the rotors. This may not be the reason why or may not be ALL of the reason why, but the science is good and is one possible explanation for it.

[zenrat]

I'm confident in your abilities Kit.  It'll all work out fine in the end.

Carry on.

[PR19_Kit]

The tubular bit on a 'dyne's blades are to get the compressed air out to the tip jets. Perhaps it needed to be cooled a tad before it got all the way out?

On the Rotocrane the air worked at higher pressure so the pipes didn't need to be so large in diameter...... 

[The backstory can always be changed to suit the model!  ]

[JayBee]

The backstory can always be changed to suit the model!  ]

Isn't it always? 

[PR19_Kit]

I reckon I'm going to have to take up Womblies idea of drilling and pinning the blades, three of them snapped while I was sanding them down. 

It'll have to be a VERY small drill......... 

[kitnut617]

The real Rotodyne's rotor blades have always struck me as a little odd.  The start about a quarter of their length out of the hub with a bladed structure, inboard of there, it is just a tubular structure.  Now, I'm sure they did for a reason but I really cannot think of one.  They could have shortened the blades by a quarter or they could have filled them in with more blade and hence increased lift.   I wonder if they did it because they couldn't get much lift out of the inner quarter because of the fuselage structure or is it just sheer bloody British mindedness which made them design them that way?   

I would say the wing and wide body would've interfered with the down wash just like on the V-22, maybe if the Rotordyne had large drooping sections like the V-22 wing has it might not have been such a problem.