Propellers for L-5

[Angel Sanz]

As this is my first time in the Stinson L5 Club, I want to take this opportunity to thank everyone to be admitted in this Club.  I would also like to ask you some questions referring to the L5.

I would like to ask you for information about the different propellers to be used in the Stinson L-5, with the engine Lycoming O-435-C.

I usually fly an L-5E of the flying museum Fundación Infante de Orleans ( F.I.O.) at Cuatro Vientos Airport in Madrid. The Airport altitude is 2.269 ft but, in Summertime, due to high temperature, we easily get a density altitude of 5.000 ft.

We actually are using a wood propeller Sensenich mod.85 R W 57.

We know that this pitch is specially for cross country flights.  As we are experiencing long take offs and low rates of climb, I would like to get some information from you about the performance with the same Sensenich propeller but with pitch 56, even with pitch 55.

I would also like to know if any of you is flying the L-5 with the propeller Aeromatic 220 in order to know your comments or views about operations on high altitude Airports.

Thank you very much,

Angel Sanz

[admin]

Hi Angel,

The 57″ pitch propeller is standard for the L-5 and is what the military primarily used during WWII. It can be considered a combination climb/cruise prop for general use and most people seem happy with it. One L-5 owner who is no longer a club member had a 55″ pitch propeller made for his airplane and reported that the climb performance was satisfactory at high density altitude but he had to be very careful not to exceed 2,550 rpm and the cruise performance was poor. Perhaps 56″ pitch would be a good compromise but I haven’t heard from anyone using one.

A few owners have the Aeromatic propeller and they will hopefully respond, but the problem is a lack of support. The only shop in the U.S. that was approved to make new blades or re-certify old ones lost that authorization from the FAA. Perhaps there is a shop in Europe that can do that work but I am not aware of one. Many owners also used to use the Hartzel HC and D-series controllable propellers, but the Airworthiness Directives governing the inspection and overhaul limits make them undesirable and expensive to maintain. They are also quite heavy at 57 pounds (26kg) and with a heavier pilot flying solo can push the aircraft center of gravity beyond the forward limit on some L-5’s, though not usually the ambulance versions such as the E-model.

Before you go switching propellers, however, be sure that the magneto timing is correct. The old military manuals specified 15 degrees advance, but that was based on 73 octane fuel used in WWII and has not been valid since 80 octane fuel was introduced. If the engine compression of EC-KSO is normal but static rpm during runup is less than 1900 rpm, the probable cause is incorrect engine timing so check with the museum’s maintenance director to ensure that it has been set properly.

For 100LL avgas, 25 degrees advance is approved by the most current O-435 Type Certificate Datasheet but that tends to cause kick-back when starting which can damage the extremely expensive starter. A good compromise is to set the timing between 20 and 22.5 degrees advance instead, whatever gives the 1900-2000 rpm static rpm performance required by the TCDS. If you do not have one, the engine data sheet is available here on the club website.

Good luck,

Jim Gray

• This reply was modified 4 years, 3 months ago by admin.

[Sam Taber]

Hi Angel, Welcome to the club !  I can share a little prop history ,but not too much else.  The original L-5 prop was the model 44K15005 made by Fahlin,  Hartzell and Sensenich.  This prop was a government designated model ( the prop design did not belong  to any of the companies who produced it).

After the war, Sensenich designed their own company prop to match the exact performance of the original 44K15005. That is the  Sesnsenich W85RB57 (or RW57) which you are flying now. I have flow both models on the same L-5 , onto same day and weather conditions and there is no difference between the performance of those two models.

I flew an L-5G out of a fuel stop at gross weight ( perhaps a bit overt:) with another club member in a 9900′ density altitude.  I don’t think I made 500 feet AGL for about 3 miles! The whole time I was looking at the “SERVICE CEILING 16000′ Placard on the panel and shaken my head:) I have had my L-5 up to 11,400′ but I was solo.

I do not have any L-5 flight time with any other prop but the W85RB57. I did talk with Sensenich Props about pitch changes when I was buying my prop and decided to stay with the standard pitch, but I am based at 860 feet altitude.

One last comment useless comment:) I have been contacted by 5 owners over the last 4 years who were switching back to wood props due to having props ( Hartzell and Aeromatic) and not being able to support those props due to no parts or no service center available.

I am sorry that none of this info addresses your question directly.

Sam Taber

 

 

 

[Angel Sanz]

Thanks to Jim Gray and Sam Taber, for your rapid and very interesting answers.

First of all, we are going to check the magnetos timing, as this is the most quick and cheap way of solving the problem.

Thank you once again,

Ángel Sanz

[admin]

For the benefit of the readers here, 44-17534 has an unusual history. It was exported from Argentina to Spain in 2006 by Juan Manuel Valle and restored by the museum staff. During WWII it served in the Philippines with the USAAF Fifth Air Force, arriving in April 1945. It returned to the USA in May, 1946 and was then sent directly to Brazil with the Joint Brazil-US Military Commission (JBUSMC). In July 1947 the plane was transferred to the 1130th and 1134th Special Air Missions Detachments in Buenos Aires, Argentina. These were cover units for the pre-CIA Office of Special Services (OSS) that was working out of the Embassy, ostensibly doing aerial surveys and mapping.  The plane was sold to the Argentine government in July, 1950.

[maurizio antonio maria beretta]

I don’t know if this can be of any help… but I sold my L-5 with a nice wooden Sensenich propeller… which had been changed years before by the last owner…

I have here left the metal propeller… it was working until offloaded…

SENSENICH CORP.  P.C.NO.1  serial 11445K

MODEL 76EM8  -O-64

in anyone could use it… no papers are coming together.

 

ciao

maurizio

[Mark Denest]

Greetings all

Speaking of props we get 10% off with Sensenich – let us know if we can help.

Mark Denest

mdaero1@comcast.net

L-5B 44-17184

[Author]

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