That correlates with the witches since it is a well known
Does Belly Landing in Propeller Plane wreck its Piston Engine? (1 Viewer)
- Thread starter gruad
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buffnut453
Captain
Don't disagree that weight is a tremendous issue for propellers. I simply don't buy that size was somehow a limiting factor that drove the Brits to employ composite wood propellers. Why not have the same sized prop but use aluminium instead?
As others have noted, the Spit went from early Merlins with 3-blade props to late Merlins with 4-blade props to Griffons with 5-blade or 5-blade counter-rotating props. That all suggests that weight wasn't the primary factor...at least not the total weight of the propeller assembly.
The whole idea that the Spitfire's small airframe meant that you couldn't install a slightly larger prop and that somehow that drove the use of composite wood props sounds bogus to me. If you have any solid explanation, I'd be glad to be corrected.
It may have been a consideration. Less weight means lower gyroscopic forces to counteract. However... a fully impregnated blade isn't massively lighter than aluminium
Tthere are so many other considerations (materials, utilising different construction skills, better fatigue resistance) that I think weight isn't a driving issue.
From the records I have seen the first 77 MKI Spitfires had two bladed wooden props and then from number 78 on went to a three bladed metal.
I think these had the Merlin III engine and the props changed over time to use the power increases from successive engine changes so it doesn't
look as though there was a weight problem.
I think these had the Merlin III engine and the props changed over time to use the power increases from successive engine changes so it doesn't
look as though there was a weight problem.
FLYBOYJ
"THE GREAT GAZOO"
Weight and balance records (if available) can tell you the difference. The 3 bladed prop should weigh more.
Shortround6
Major General
I have read that the early Spits with the light propeller had ballast weights in/on the engine mount.
Later Spits had ballast weights in the rear fuselage?
the three bladed metal DH 2-pitch prop 350 lbs. and the constant-speed 3-bladed Rotol or DH prop 500 lbs.
Perhaps the converted DH props weighed less or perhaps the pump or pump controller weighed 150lbs?
The two pitch prop did have a pump.
Later Spits had ballast weights in the rear fuselage?
the three bladed metal DH 2-pitch prop 350 lbs. and the constant-speed 3-bladed Rotol or DH prop 500 lbs.
Perhaps the converted DH props weighed less or perhaps the pump or pump controller weighed 150lbs?
The two pitch prop did have a pump.
Bigger/more complicated hub, extra blade, governor could easily account for that extra weight.
Shortround6
Major General
three bladed metal DH 2-pitch prop 350 lbs. and the constant-speed 3-bladed Rotol or DH prop 500 lbs.
In June or July of 1940 DH made 500 conversion kits for the 2 pitch propellers and sent teams out with trucks to the RAF fighter fields where they changed one prop from 2 pitch to constant speed while the mechanics watched. The mechanics changed over a few more while the men from DH assisted/instructed the hands on. When satisfied the the DH team would leave enough conversion kits to complete the squadron and drive to the next airfield to do it again.
The 2 pitch prop had 20 degrees of pitch change. No mention is made of changing the hubs, just modifying the pumps the governor and the controls in the cockpit.
Rotol props often had 30 degrees of pitch change, Some tests say that the DH props in the test had 20 degrees of pitch change but don't say if they are new or converted.
Later DH props had 30 degrees or more of pitch change.
A lot of unkowns but the reason that they could use conversion kits was that the DH prop had the 20 degree hub and a hydraulic pump to power it to begin with and a control in cockpit to switch from fine to course and back again.
20º is only going to give you limited constant speed ability.
Are you sure that the conversion was into the same model propeller? I would have expected the pitch travel to be at least twice that to be really effective.
The hub was changed early in the "piece" the Merlin Mk III was the Mk II with a SABC (Society of British Aerospace Companies), hub standardised to take DH props and the newly formed ROTOL,
pinehilljoe
Senior Airman
- 731
- May 1, 2016
In wartime, and a remote field it probably depended on the spares on hand.
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
The founder of Hamilton Standard was Thomas Hamilton.
Hamilton Standard besoms and brooms was a different company I think.
Shortround6
Major General
Hamilton standard propellers was a wholly owned subsidiary of Hamilton Standard besoms and brooms and fronted for them in order to keep the New England Puritans quiet.
buffnut453
Captain
No, no, no...it was Alexander Hamilton.
I'm sure I heard "propeller" mentioned in one of the musical's "songs".
Then again, my ear isn't very well tuned to (c)rap.
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
I know Perry Mason always gave Hamilton a hard time in court...
Barrett
Senior Airman
The aviation term I knew from my teens (creak) was "sudden stoppage." Many replies have provided insight regarding engine effects. I CANNOT PROVE IT but sorta recall one or two Spitfire pilots saying that the wooden blades shattered on impact, thus reducing the effects on the engine.
Shortround6
Major General
RR did come up with repair solution for cracked reduction gear cases at overhaul facilities. Not unit repair.
The was a strut that was added between the top rear of the reduction gear case to the top of the crankcase to reinforce the welded gearcase.
Certainly doesn't mean that every cracked/broken gearcase/block could be repaired.
The was a strut that was added between the top rear of the reduction gear case to the top of the crankcase to reinforce the welded gearcase.
Certainly doesn't mean that every cracked/broken gearcase/block could be repaired.
