Aeromatic props

[zero.one.victor]

George,you reaffirm what I seemed to recall about the Aeromatic prop: "aero/mechanically controlled" .I like the way you put that. So,why does the TC state that it can only be used with the C-145-H engine? Anybody?

Eric

[GAHorn]

Eric, look at the MX Library for a more detailed description of the Aeromatic prop and Beech Roby Props.
In answer to your question regarding the "H" engine, I believe it's going to be another case of coincidence. The Aeromatic does not use hydraulics whatsoever, but the -2H engine may have been the engine in use to obtain the type certificate. Remember that the -2H engine has provisions for hydraulic prop, but the plug was never removed in most of these engines and therefore they were not used with them.

[Trapper]

Hi everybody, Great Site George.
Here is a E-mail I recieved from Kent Tarver re Aeromatic F200-H and C-145-2H engines. The prop I have is a F200 and dosn't require the engine oil to opperate, should work on my 0-300A engine. I will be trying it as soon as I get it recertified.
Thank you for all the imput on this subject.
Trapper

H is the designator for a F200 that has what they called High Cruise or also
known as High altitude prop. It has a cylinder bolted on the from of the
hub and it gets oil through a hollow crank shaft in similar fashion to the
constant speed prop but the pilot has a handle in the cockpit which allows
him to override the automatic function.


Assembly number 4389-1 was set up for the Aeronca 15AC but there is very
little difference between the two airplanes.


I have the seals and shims. I know of A-1, have talked to the chap that
works on Aeromatics. Yes, have them open it up and find out what they need
and I can send you the parts.


I guess you know about my Service Bulletin 200-001 and perhaps the FAA's
SAIB NE-01-23. Be sure they back out at least one lag screw in each blade
to check for rust. And of course all the screws must be given 150 inch
pounds of torque.


Good luck.


Kent

[lowNslow]

Could it be that the Aero-Matic prop requires a dampened crankshaft - I thought that was what the "H" stood for.

[GAHorn]

Could it be that the Aero-Matic prop requires a dampened crankshaft - I thought that was what the "H" stood for.

The "H" stands for hydraulic crankshaft and crankcase. A dampened crankshaft is denoted by a letter "D" within the engine serial number.

[zero.one.victor]

Like george said,the D in the serial number indicates a dampened crankshaft--meaning it has centrifugal counterweights to make it run smoother. The earliest C-145's as well as the C-125's didn't have this feature.
The H in the model number indicates a dampered (not dampened) crank,this would be a sort of valve that meters flow of oil into the hollow crank to control a hydraulically operated prop.

Eric

[GAHorn]

Like george said,the D in the serial number indicates a dampened crankshaft--meaning it has centrifugal counterweights to make it run smoother. The earliest C-145's as well as the C-125's didn't have this feature.
The H in the model number indicates a dampered (not dampened) crank,this would be a sort of valve that meters flow of oil into the hollow crank to control a hydraulically operated prop.

Eric

The "H" indicates a Hollow crankshaft that conducts oil to the prop IF it's installed in a "H" crankcase, and IF the front plug is driven out of the crankshaft. Othewise, it operates just like any other crank. (All the later cranks were hollow and had this plug.)

[zero.one.victor]

Whether the hollow crank is plugged or not, I believe the little crank-handle looking gizmo on the R.H. side of the case,behind & below the prop,is the giveaway that it's a C-145 H engine. This would control the damper that meters the amount of oil going into the hollow crank when a hydraulically controlled prop is used. Even if the crank plug is in place,it's still an H engine,right? I'd say to check the data plate,but an awful lot of them are pretty much worn smooth & illegible.....

Eric

[GAHorn]

The H engine has a valve near the left front oil gallery that controls oil flow to the special crankcase gallery. I'm reluctant to call it a "damper" because I've never heard it called that and I'm afraid some may confuse that with a dampened crankshaft, ...entirely different parts, locations, and purposes. TCM calls it a valve. The C-145-2H engine is similar to the O-300-B in it's hydraulic prop provisions.

[zero.one.victor]

The 170 type certificate sez:"Propeller-Koppers Aeromatic F200-H/00-74E......................and C-145-2H engine with dampered crankshaft are required.....".

Eric

[GAHorn]

The 170 type certificate sez:"Propeller-Koppers Aeromatic F200-H/00-74E......................and C-145-2H engine with dampered crankshaft are required.....".

Eric

You don't suppose the FAA could make a mistake? TCM Engine Manual X30013, Overhaul Manual for Models C125, C145, and O300, on page 6, Paragraphs c and f, calls it a "valve" for oil controlled hydraulic propellers (which the Aeromatic is not), and calls it a "dampened" crankshaft.
This will make more sense when you think about crankshafts. They have no valves or "dampers". (Dampers are in fireplace flues.) Crankshafts cannot be "dampered" because they are hollow and have no mechanism to regulate oil flow whatsoever. They only have fixed-orifices and passages. Any oil flow in a crankshaft can only be regulated externally to the crankshaft.
Not even crankcases have dampers. A damper would be a restrictive device. Oil pressure is regulated in these engine crankcases by spring loaded relief valves, not any sort of damper. Even constant speed props don't use dampers. They use governors which boost pressure, not restrict it.
The only purpose of any dampening device in our engines is for the sole purpose of dealing with vibration. Specifically, in the C145/O300 engines, it's to deal with the fifth overtone of crankshaft vibration and the sixth overtone, in order to prevent excessive vibration of the crankshaft gear and resultant excessive wear of gear teeth. It has nothing whatever to do with oil.

[Tom Downey]

In accordance with the Cont. C-145/0-300 over haul manual the "H" in the designation means the engine is a "Hydraulic" Engine.

This means the engine is equipped with a hollow crankshaft forward of the front main bearing, and a valve which controls oil pressure thru the crankshaft to the prop, which allows the use of a two position, hydralic prop. These props use Centrifugal Twisting moment (CTM) to return the blades to low pitch and engine oil pressure to force the blades up to a high pitch in cruise flight.
These props are NOT constant speed props, they have a high pitch setting and a low pitch setting, and this is the only places they will operate. (cruise or climb)

Koppers Aeromatic made several props of each type. The Koppers Aeromatic F200-H/00-74E. is the 2 speed type not the ground adjustable or the constant speed just the old climb or cruise 2 speed.

Crankshaft dampening is for Vibrations of the 5th order, it is done with weights placed on the crankshaft and allowed to float in their bushings to seek the low spot and stop the vibrations which harm our gyros, these are the cranks that the "D" engines have, Remember the "D" engines have a vac pump and a full gyro panel.

Hope this helps to dispell the old wives tales of what the H & D stands for.

[GAHorn]

these are the cranks that the "D" engines have, Remember the "D" engines have a vac pump and a full gyro panel.

Hope this helps to dispell the old wives tales of what the H & D stands for.

As a clarification Footnote: "D" engines (O300D) do indeed have a dampened crank, but that's not what that "D" in the engine-model stands for. That "D" in the engine designation stands for other mods, such as the vac pump and angle-starter variations, etc,.
The "D" that designates a dampened crankshaft (which can be installed in any engine) is found in the engine serial number, i.e., such as in
Continental Model O-300-C, SN 20565-D-O-C (which is in my own airplane).

[bagarre]

I just got an email from Kent.
We were talking about fitting an Aeromatic prop to my 170:

You have the 0-300D. I can make a prop for that engine. I did one for a
Swift that had the same engine. I have attached the TCDS for your airplane.
It shows the F200H propeller. The C-145 had a hollow crankshaft, that is
why they called out the F200H. We don't support the H version of the prop.
The only difference in the props is that the H version has to have a hollow
crank so that the pilot can override the automatic function of the prop at
high altitudes. That is why the data sheet calls for the F200H.

<clip>

High altitude means above 7-8 thousand feet and up.
It can be left outside but it should have a cover for it. The hub is water
proof and metal parts exposed is CAD plated, the blades are covered with
fiberglass. The same basic construction and the MT props. "

So, it sounds like the F200H propeller did have a Hydraulic feature to at least lock the pitch of the prop.

Is there ANYONE that is actually flying with an Aeromatic prop on a 170 With out the -2H motor?
I'm not really interested in more speed (or I wouldn't be flying a 170) but rather more climb.
Say: a propeller that can act like a 51" and 55" when appropriate

[Bruce Fenstermacher]

Wow. Very cool.

You have unlocked a mystery as to why the TCDS would require the -2H engine with the Aeromatic Propellor.

To bad they don't support it.