Propellors on DC6/7, Stratocruiser, Constellation & Britannia

[b377]

( This thread also appears under TechLog my appollogies for repetition I'm not sure which heading is best)

On topics about the DC6, DC7 and Constellations & Stratocruisers mention is often made of the props used on the Wright and P&W engines as being either Curtiss Electric (CE) or Hamilton Standard (HS).

I have had a long standing query as to why some aircraft like the B377 used square tipped props on some a/c while other Strats (even owned by same operator such as BOAC) used rounded tips? Same goes for the DC6 and DC7s. Is it possible to visually tell apart a CE vs. HS propellor?

I have also noticed on a few Britannia pics that some a/c have rounded tip props and others square tipped and even seen mixed square/round props on same a/c. These were presumably Rotol?

I know prop hub spinners were optional kit so this easily explains this difference.

[WHBM]

I believe the BOAC Strats that had the different type of props were secondhand acquisitions. There were window differences on the airframe as well.

[b377]

Yes, Pan Am, BOAC, North West, United & SAS all ordered their own window shape preferences for the main and lower cabins (bar) not sure if ordering different tipped props served a similar cosmetic purpose :)

(BOAC did of course acquire ex Pan Am & United airplanes and all of the SAS fleet from new.)

[evansb]

Generally, tapered blades are capable of higher speeds, and squared-off blades push more air for a given RPM and air density. Chord, aspect ratio, sweep, pitch and tip speed (mach) are all major factors when matching a prop to a specific engine application.

Note that most Vickers Viscount 700-series have tapered tips and Viscount 800 series have squared-off tips. The photo below shows an early BEA 700-series Viscount with experimental high-speed tips. Efficiency and noise are major considerations in propellor design, not aesthetics.
http://i141.photobucket.com/albums/r68/convair640/V700HStips.jpg

[b377]

All very well but that still leaves the fact that both tappered and squared-off tips were used interchangably and at times the same airframe sported the two types at the same time. There is a very good pic in airlines.net showing a Britannia fitted with mixed tip props.

To me squared tip props are 'smarter' looking.

[evansb]

The photos on airliners.net of Britannias with dissimilar propellors are both Canadian Pacific Airlines Britannias. Both aircraft have the dissimilar prop installed on the number two engine. One photo shows a near-new aircraft outside the company hangar in Vancouver. The tapered tip propellor has rubber boot leading edges versus the bare edge of the square tip propellor. Given the intake icing problems of the Bristol Proteus engine, perhaps this unusual propellor configuration was an in-service test and assessment of props and icing.

Whatever the reason, it is thought provoking.

A good example of propellor suitability is the Lockheed L-188 Electra/P-3 Orion. Both models are powered by the Allison turboprop, but the operating profiles of the two models are quite different. Wth the exception of the original American Flyers and KLM Electras, the Electra has square-tipped props, and the P-3 has round-tip props.

[b377]

Photos: Bristol 175 Britannia 312 Aircraft Pictures | Airliners.net (http://www.airliners.net/photo/BOAC/Bristol-175-Britannia/0093611/L/&tbl=photo_info&photo_nr=31&sok=WHERE__%28aircraft_generic_%3D_%27Bristol_175_Britannia% 27%29_AND_%28airline_LIKE_%27BOAC%25%27_AND_airline_NOT_LIKE _%27%25BOAC-Cunard%25%27%29_&sort=_order_by_photo_id_DESC_&prev_id=&next_id=0093610)

this link shows the pic in question, an in-service BOAC 312 with mixed props (at least on 3 & 4).

One example of many I've seen not just on the Brit but also b377 & dc6/7.

Obiously something to do with spares holdings and interchangability.

[b377]

Bingo!


http://cdn-www.airliners.net/aviation-photos/photos/1/1/6/0093611.jpg

[WHBM]

The photos on airliners.net of Britannias with dissimilar propellors are both Canadian Pacific Airlines Britannias. Both aircraft have the dissimilar prop installed on the number two engine. One photo shows a near-new aircraft outside the company hangar in Vancouver. The tapered tip propellor has rubber boot leading edges versus the bare edge of the square tip propellor. Given the intake icing problems of the RR Proteus engine, perhaps this unusual propellor configuration was an in-service test and assessment of props and icing.

Whatever the reason, it is thought provoking.
Could the photo have been taken when they were 1/4 way through a prop change ? Would have thought an unbalanced mixture would be bad news (rather like mixing your tyre types on the ar).

[b377]

Round

http://cdn-www.airliners.net/aviation-photos/photos/6/5/4/1279456.jpg

[b377]

http://cdn-www.airliners.net/aviation-photos/photos/0/4/5/0074540.jpg

[b377]

http://cdn-www.airliners.net/aviation-photos/photos/5/1/8/0858815.jpg

[b377]

http://cdn-www.airliners.net/aviation-photos/middle/9/6/3/0121369.jpg

[evansb]

In the Britannia examples, the tapered tip, rubber-booted props were located on the inboard engines. As well, the Britannia photos were taken in the early days of the Britannia's career. I don't see any examples of dissimilar props in later photos. Any ex-Britannia engineers care to comment?:)
http://i141.photobucket.com/albums/r68/convair640/CPA-Britannia-YWG-pigott.jpghttp://i141.photobucket.com/albums/r68/convair640/CPA-Britannia-YVR-pigott.jpg

[Brian Abraham]

Taken from the respective type certificates. Well you did ask.

Britannia 305
De Havilland P.D. 202/4N6/2
De Havilland P.D. 208/466/2

DC-6
Hamilton Standard
43 D60/6825 (Not permitted on -83A or -83AM3 engines)
43D60/6841
43D60/6851
43D60/6873
43E60/6895 (Only prop permitted on CB16 engine. Only prop permitted on DC-6A and –6B)
Curtiss
C632S-B/744-6C2
C632S-B/744-4C2-0
C632S-B/744-10C2
C632S-B/836-14C2
C642S-B/836-14C2-18

DC-7
Hamilton Standard
34E60/6921
34E60/7019 (DC-7C only)

Boeing 377
Hamilton Standard
Hub 24260 fitted with either 2J17B3-8W, 2J17F3-8W or 2J17H3-8W blades
34E60/7015-29 (Supplemental Type Certificate for use on 377MG [Cargo only aircraft])
Curtiss
Hub C6445-B302, Blades 1052-2004-30

Constellation 1049
Hamilton Standard
43E60/6901-02
43E60/6903B-0
43H60/6959B-0
43H60/6967-0
Curtiss
Hub C634S-S, blades 858-5C4-0
Hub C634S-C500, blades 830-21C4-0
Hub C634D-A2, Blades 109652-12
Hub C634D-A4, Blades 109652-12

Anorak off.

[pjac]

Pardon me for saying, EVANSB- but the Proteus engine was a Bristol, not a Rolla

[Brian Abraham]

True pjac. Stanley Hooker (later Sir) was head of the program if I recall. He later lead RR and came out of retirement to get the problems on the 211 solved. Did RR take over support of the engine after Bristol sank out of sight? Maybe source of EVANSB comment.

[b377]

evansb ...Quote: " were taken in the early days of the Britannia's career. I don't see any examples of dissimilar props in later photos .... "

The picture of the BOAC Britannia above featuring mixed props is from May 1958, I wouldn't call that early in its carreer - if the 102 is included of course.

Brian Abraham

Thanks for the Brit prop info I thought they were made by Rotol as in the Hovercraft that also use the Proteus engine much later.

As regards to the B377 prop list, several blade options were apparently available for a given hub, some may have been tapered others square (?) explaining the difference but otherwise interchangable.

However a wing symetric arrangement must have been necessary to avoid differential torque problems (unless both blade types were equally effective at a given pitch and RPM )- In the case of the Britannia the 4 Proteus engines were intended to run synchronised to reduce vibration, although this was never achieved exactly I was told once, which explains the characteristic slow modulation (beat) in the sound of a Brit flying in the distance as the engines came in and out of phase.

Oh that Wispering Giant !

[evansb]

Yes pjac is correct. Bristol built the Proteus.

The Bristol Siddeley Proteus was quite an engine, powering the Saunders-Roe Princess flying boat, RN patrol boats, a frigate, a hover-craft, and even Donald Campbell's Bluebird land speed record car.

The Britannia entered airline service in 1957, so I would say 1958 is still early in the aircraft's career.

[dusk2dawn]

What kind of R-2800 had D-spline?

[Brian Abraham]

dusk2dawn, your question is a little short on information, presumably you are referring to the prop spline. To that question the answer is the "A" and "B" series engines had a SAE #50 spline and the "C" series SAE #60. Hope that answers.

[tonytech2]

On the B377, the Ham Standard props originally fitted had square-tipped hollow steel blades. Gave tremendous problems finally leading to a Airworthiness Directive requiring for frequent magnetic inspections of blades. They changed over to solid dural blades and these had the rounded tips. United Airlines, uniquely I believe, had Curtiss Electric props fitted. On the sale of the UAL B377 fleet to BOAC the aircraft were converted to Ham Standards requiring, in addition to major wiring changes, removal of the engine nose cases for rework and installation of oil passages.

United also, I think alone of the B377 operators, did not have a proper flight engineer's station but seated the FE just behind the throttle pedestals facing forward. All the engine instruments, etc that were normally on the FE panel were up front. BOAC required installation of an FE station plus conversion to HS props and this required almost complete gutting of electrical looms in wings and fuselage and their replacement. The B377 was almost all electric in operation so this was a major project.

These aircraft also went to higher density seating and this mandated installation of an additional overwing exit on each side. UAL aircraft had the square windows.

All this work was done at Lockheed Air Service International (LASI) at Idlewild International Airport (KIDL) in New York. Was said to be one of the biggest conversion projects done at that time. DeHavilland props were license built modified Ham Standards. The Bristol Britannia had these fitted. Like the Stratocruiser, they went from the steel to the solid dural blades and that is when the tips went from square to rounded.

Prop configurations were quite variable and dependent on customers preference. Many L-749 Constellations, expecially those of non-US companies utilized Curtiss Electrics which had quite a broad butter-paddle shape for their steel blades. USAF C-121A (L749 types) Connies had them too. Later military Connies (L-1049 types), USAF and US Navy all had Ham Standards. Seaboard and Western Airlines had Curtiss Electrics (square tips) on their L-1049 D and H models. Their single L-1049E-01 passenger aircraft had Ham Standards.

Northwest Orient sold their four L-1049G Connies to LAV of Venezuala. These had Ham Standard props but they were squarish-tipped dural blades (rouned corners) and, unlike any other Connies I ever worked, had electric prop deicing boots on the blades. These required alternators to be fitted on the inboard engines for power. All other Connies I saw had alcohol slinger rings and rubber distribution boots on the blades.

Only DC-6 I worked with Curtiss Electrics was a VC-118 that LASI converted from HS to the Curtiss for USAF for a cold-weather mission. I know there were other civil DC-6 with Curtiss props but I never saw any by 1954 when I started work.

Most Electras had Aeroproduct props with square tipped steel blades. American Flyers and KLM had Hamilton Standards. Customer's choice again.

[dusk2dawn]

Brian Abraham, you're right - thanks. It's been some 37 years since I worked at an HS prop overhaul facility and memory lane is somewhat fuzzy.
Do you have on-line access to the TCs and if yes then where?

[Brian Abraham]

Go to http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/MainFrame?OpenFrameSet, click on "Product Type" on the left, click on "Search" on the next page and enter whatever it is you're after. Have fun!!!

[dusk2dawn]

Good stuff. Thank you!

[evansb]

Square-tips look good on this beast. Better to see this bird when she was flying so fast and low you dare not blink because you would miss her, let alone the blades!
http://i141.photobucket.com/albums/r68/convair640/0770-066-00001-supersnoopy-8.jpg

[merv32249213]

In answer to the question why some had round tipped props and some square. In the case of the Brits the square tipped ones were hollow and internal corrosion was starting to take place, and solid steel props to replace them ,were in short supply . The mix and match was a nightmare, as us engineers we were moving props from one engine change to another . As far as I remember we could never fit two of the same to one side only, but could have one of each on both sides . It was great when at last we could have a full set of round ones on one aircraft.
In the engine bay you could not prepare a powerplant with a prop fitted as you never knew what type was on the engine that was to be replaced . Engine changes on Brits were many and frequent and the prop situation made it hard work. Alot of strength was needed to change the props when the removed ones placed on their transit dollies.
Anyone who was involved with Brits will know what I am talking about .
Merv

[b377]

Merv

Good to hear from someone who actually worked on the old Brit.

So the migration was from the smart square props to the round ones , who made them deHavilland ? Else where in thread it is mentioned that DH made the props under license from Hamilton.

The story is similar to the Stratocruiser corrosion problem with the change to HS round tipped props.

[Tempsford]

Merv,
Remember the blue and red oil tubes for the prop PCM? one
pipe was LHT and the other right hand thread. You sure did need to hold the two lower prop blades steady whilst the prop was being placed/removed from the dolly. Carrying the PCM to/from the prop using that large spanner was interesting if there was any oil on the access stand. I don't think I have ever worked on an aircraft where we did so many prop/engine changes on a regular basis. I can remember 3 engine changes on one a/c in one night. As apprentices we were given the task of taking the props apart, removing the anti-ice mats, paint stripping the blades, removing the lead core balance weights and then rebuilding the prop assembies. Good experience for young lads. When the PCM had been fitted the usual call was 'who has the grub screw?'. Usually the screw driver slot was mangled so it was a good idea to have some spares in your toolbox. Once the prop was fitted, feathering checks and after that the need to drain the oil from the sump and put it back into the oil tank (we sometimes used to do that at night with the engine still running and prop feathered!- not very H&S!) The airport fire brigade was used when asked to help us try and get the engine torque in limits by spraying water down the intake during EGR to clean the compressor blades.
I can also remember the significant variation in the location of certain switches in the flight deck for different Britannias. The flight deck layout was not standard.
One time I saw the strength of a Brit prop was when an a/c arrived on stand and the guy putting the steps on the L2 Door drove to the door (engines still running), and then ATC asked the pilot move a bit more onto stand. The #2 prop then proceed to 'eat' the steps.

Temps

[b377]

Temps

you're a tad younger than me so you must have been in dypers if you worked on BOAC Britannias. Probably much later with B Cal or RAF brits?

[merv32249213]

My work was at Britannia's (1966 onwards). who inherited some of the Ex BOAC ones and to add to some of the comments, yes the round tips were made by De Havillands under licence,. Glad to hear the comments from people who actually worked on the beasts. As a reminder of that time I still have a torque bleed tube for the engine ,and special tool for setting up the prop microswitches in my retired toolbox.
Merv

[b377]

What did those engines sound like? Hard to tell from sitting inside as a pax.

I doubt they sounded at all like a Tyne or a Dart - as on Vanguards and Viscounts.

The sound of a Britannia flying over head was quite distinctive.

Any one know of a good recording of a Brit ?

[tonytech2]

It wasn't called the "Whispering Giant" for nothing - it was probably the quietest turboprop of all - it had to be - the actual engine was buried inside the thickest cowling ever, it had the intake air passages running through it. The 180 degree turn where the air went inward and entered the compressor was well back and so inlet noise was muffled. and the tailpipe was so long it made a muffler too. So actual engine noise was very low. At power of course, the prop made a good deal of noise.

Of course the joke was to call it the "Whimpering Giant" with four mighty "Protesting" engines. I was chastized once for calling it that by a former Bristol exec and I informed him I had learned it from a Bristol engine rep who fortunately had long retired.

[Tempsford]

B377

IAS, Cubana, African Safari, Donaldson, AFREK, Monarch, AMAZ, Aer Turas, Katale, Invicta, Redcoat, Interconnair, Geminair, ex RAF, Aerocaribbean,to name but a few, not quite in diapers when BOAC had theirs, I was too busy flying in the flight deck of TCA L1049's with my dad whenever I could. Perhaps this is where I got the bug to work on aeroplanes:}.



Temps

[b377]

You bastards had all the fun .. didn't you .

but perhaps you didn't think so at the time...

good for you !

[Tempsford]

You are quite right. At the time we had no idea how much fun it really was. Nowadays, in the clinical, sanitised world of the boring lookalike metal 'tubes' the fun and interest has indeed gone. I only caught the taill end of the good times, but wouldn't have missed it for the world.

Temps

[reality1]

I need a De-Ice Boot for a DC 7 Prop. It is for a display and does not need to be airworthy. It is 42/43 " long.

Please e mail me if you know of a solution.
Thanks, Jim

[Hot 'n' High]

evansb

Post 4 Note that most Vickers Viscount 700-series have tapered tips and Viscount 800 series have squared-off tips. The photo below shows an early BEA 700-series Viscount with experimental high-speed tips.

Very interested as I'm doing some research into various the various Viscount blades. The change from taper, or "Needle" blades to square-tipped, or "Paddle" blades, took place when the Dart 510 was introduced for the Capital and CAA orders. There are also 3 variations in the square-tipped "Paddle" props, including the "Trapezoidal" blade fitted to the Dart 525 but I'm still bottoming them out! :ugh:

Regarding the blades in the photo, known as "Cutlass" blades, these were fitted to the 2 Dart-Daks which did route/turboprop proving flights round Europe and to the early Viscount 701s and 708s for BEA and Air France with Dart 505's fitted. They had copper leading edges riveted on and there were, by all acounts, reliability issues with the blades + they were expensive to repair.

As the Dart 506 was introduced, so too was the "Needle" blade. The early 701's and 708's also had their engines upgraded to the Dart 506 and the "Cutlass" blades vanished with the Dart 505's. The upgrade often took place 2 engines at a time so, for a while, the 701's and 708's could be seen sporting 2 "Cutlass" and 2 "Needle" props. Later production 701's and 708's went straight to Dart 506's so they only flew with "Needle" blades. :bored:

Interestingly, I have not seen any record of the Viscount prototypes with "Cutlass" blades, the first flight appearing to be with non-standard "Needle"-type blades. I believe the Darts were also earlier, 504's if I recall. Anyway, if anyone has anything on Viscount blades, particularly details on the at least 3 versions of the "Paddle" blades, or comments on the above, it would be great to hear from you. :ok:

Cheers, H 'n' H

[Brit312]

Now as a very young man with BOAC in the early 60s I seem to remember that the Britannia 102 had square tipped hollow blades whereas the 312 had round tipped solid blades.

When BKS operated the 102 they had square blades but near the end of their life you would see them using the round solid blades, presumeably because the hollow ones were becoming hard to find.

Now from the pictures above it would seem that it was allowable to use, in matched pairs, either type prop on either model.

Being a Comet 4 boy at the time I was not that close to the Brit, but I seem to remember that other than the corrosion problem with hollow blades they were also very sensitive to Foreign Objects damage as unlike the Dural blades you could not dress out nicks in the blade.

Some good photos thanks:D

[reality1]

Could someone explain to me what is "dural"?

I have searched and could not find out exactly what metal is in the solid prop.

[Brit312]

Dural is the popular word for Duralumin which is an alloy of Aluminium and copper with manganese and magnesium in small quantities thrown in as well

Aluminium makes up about 94% with copper about 4% and thus you get a light but strong alloy. It has one draw back that it suffers from corrosion and that is why you see aircraft that are built from this alloy are painted to prevent the corrosion.

The industry also produced alcad sheet, which uses dural as a core and pure aluminium bonded to both sides, the aluminium in this case giving the protection against corrosion.

Brain hurts now so will stop

[reality1]

Brit512, Thank You,

Jim

[Brian Abraham]

I was very interested to learn that the problem with the hollow blades on the 337 was not corrosion as I had previously thought, but sourced to an entirely different problem.

Within a couple of weeks of the January 1950 Stratocruiser blade failures, the Civil Aeronautics Administration (CAA) ordered close inspections of Model 2J17 propeller blades. A tapping test of the blades was intended to detect fissures in the filler material of the shell cavities. The CAA also ordered a magnetic inspection for cracks when the aircraft made its first stop at its main base. Any blades with cracks or large filler fissures had to be removed from service. As noted in the Brazilian accident report of 06/26/53:
“…with less than two years of service experience, longitudinal cracks were found in a number of blades in the outboard blade portions, about four inches from the leading or training edge and parallel to the edge. These cracks were found to be due to the black rubber filler in the blade breaking and allowing the steel shell of the blade to vibrate locally from aerodynamic buffeting.
At this point the blade design was again altered by using nylon-rubber filler instead of black rubber, the nylon filler being tougher and more resistant to shattering. A daily tap test, required as an interim measure, to locate any internal voids that were occurring in the blades with the black rubber filler”.
Another modification was the introduction of a nickelplated hollow steel blade for Boeing 377 aircraft in early 1954. The CAA certified this blade, manufactured by Hamilton Standard, for air carrier operations on September 14, 1953. This blade was a bit heavier than the unplated one
because of the plating. Hamilton Standard hoped that the plated blade would be less subject to damage from foreign objects picked up by the propellers.
The CAA made installation of propeller blade imbalance detectors mandatory as of July 30, 1955 on Boeing 377 aircraft.
The detectors enabled the flight engineer to identify which engine or propeller was malfunctioning and to shut down the engine and feather the propeller.
The C.A.B. administrator stated the final cure for the problematic hollow steel blades in a letter dated June 28, 1955:
“As a result of this investigation, and of the investigations conducted following six other accidents or serious incidents, we have concluded that, in the interest of safety, the Hamilton Standard Model 24260 propellers having 2J17 series hollow steel blades presently used on Boeing B-377 aircraft should be removed from service and replaced with propellers having solid metal blades. This shall be done at the earliest possible date consistent with the ability of the propeller manufacturer to supply satisfactory blades.”.
The final governmental action in the hollow steel-bladed Boeing 377 Stratocruiser was an issuance of an airworthiness directive in the fall of 1958.
Airworthiness Directive
AD 58-19-02 HAMILTON STANDARD: Applies to All Hamilton Standard 2J17 Hollow Steel Propeller Blades installed on Boeing 377 Aircraft.
Compliance required as indicated.
Operators that are using or have used these blades learned through adverse experiences that exceptional maintenance procedures and repair techniques are required to assure the continued airworthiness of these blades. In order to preclude the possibility of additional adverse experiences occurring either under the supervision of the present operators or other operators who will acquire some of the involved aircraft, the following shall apply:
1. Not later than August 1, 1959, remove from service all 2J17 Series propeller blades.
2. Prior to August 1, 1959, no operator who has not had previous experience in the overhaul and maintenance of 2J17 Series propeller blades shall be issued a certificate of airworthiness for aircraft on which these blades are installed.

[ExSp33db1rd]

Thanks for all the Strat. and Brit. memories - glad I'm not an engineer, I only had to navigate them ! that was fun, too, [ in retrosepect ! ] Sextant, Loran, Consol - finger out of the window -happy days.

[Volume]

Could someone explain to me what is "dural"?A quite common misunderstanding is that "dural" comes from "dur" (latin for "hard") and "Al" for aluminium, because it is an alloy which could be hardened.
Actually dural has been inventen and named by by "Dürener Aluminiumwerke" (Düren Aluminium Works) in the west german city of Düren, located between Cologne and the Dutch/Belgium border.
Dural became famous when it was used for the Zeppelin structure around 1900.