PROPS  (page two...)

O-300 PROP QUESTION...  (10499)
From: Ed Lloyd <>
The logs say I have a Sensenich 74 DC-0-60 prop installed now. On takeoff @ WOT, I'm turning about 2550, and the takeoff roll seems just a bit longer than I would like. It's coming unstuck at about 60 and I'm climbing @ 80 MPH. On leveling, and reducing RPM to cruise I'm showing about 9.5 GPH on the Swifttronics. That's giving me about 2350 to 2450 RPM at cruise. If I push over and get the bird "up on the step", I'm cruising at 135 to 140 MPH. Not being familiar with the Cont., are these figures in a normal range or should I do some adjusting? Do you know if Continental Motors would have any kind of Ops Booklet I could purchase from them? If so, what should I ask for. Hope I've given you enough background for you to evaluate. Thanks in advance, Ed Lloyd

With a 60" pitch, you cannot expect too much initial acceleration, but that should be about right for overall performance and best cruise speed. 9.5 gph is a little too high at 2350 rpm. I lean whenever below 23" or 2400 rpm, at 23"x2400 I burn about 8 gph. TCM has an Operators Manual for Aircraft Engines - O-300 and "C" series form X-30015, which is very good, it is just a little booklet and only costs a couple of bucks. It has power charts and a lot of information not found any other place. -- Jim

FIXED PITCH PROP FOR LYC. O-320...  (10299)
From: Bill Doty <>
Long time , no contact !! As usual, I need info. ,,,, I am ready to purchase prop. for N80572 ... As you may remember I have a 150/160 h.p. lycoming engine...Thought you might have a recommendation on size and where to purchase. Also, what spinner would fit on the plane/prop combination. Polishing is coming along (slow) but getting there. Still have (1) wing , vertical stab. and rudder , plus some trim parts, to go ... Would like to plumb up the engine and start it , to check out the top overhaul job. then ready to reassemble the plane..Looking to be ready for next spring...As usual , thanks for your help.. BILL DOTY

I am presuming you are giving up on the constant speed because of AD 97-18-02, is that right? First of all, the HC-82XL is not necessarily junk, it can be inspected per the AD note. I have seen quotes from $600 to $1200 to do the inspection. The bad news is, many times (expensive) parts replacement is required and the time before the next inspection is rather short. (sorry I can't quote it, I haven't read the AD in a while, it depends on several factors) If you would want to get your HC-82XL inspected, I have one here that could be used for parts. (actually a HC-82VL, removed from an Apache) It looks perfect, but of course it needs AD 97-18-02 - that's why it was removed. If you want to go to a fixed pitch, I would use a 72" dia. and 59" pitch prop. I forget the numbers for a 150 Lycoming, but talk to a local mechanic, a prop shop, or the FAA for advice on that. You will need a field approval from the FAA. They have to consult engineering on every prop field approval, so it helps to contact the manufacturer and get their recommendation. A lot of spinners will work, figure the diameter you want, find a part number, then get it approved along with the prop. Look in the Aircraft Spruce catalog or some other aircraft parts catalog. -- Jim

AEROMATIC PROP...  (11299)
Subject: Re: Prop
From: Larry LaFroce <>
Jim... Have you ever seen a Aeromatic 73x59 ? I have not heard of anyone using one. Is this the proper prop for a C-125 powered Swift? The Aeromatic that I am speaking of is a fixed pitch. The one you spoke of is a variable pitch? I have heard of these... but have never seen one (the variable pitch).  Thanks....Larry

Back in the '40's and '50's most "Deluxe" Swifts had that prop (Aeromatic). There are not very many still around. The maintenance requirement is quite high and they are expensive, if you can find one. Plus, the cruise speed is not too good, about 120 mph with a C-125. They do get off pretty good and if everything is right, work as a self contained constant speed prop. There is no such thing as a fixed pitch Aeromatic. There is a "Flotorp" fixed pitch prop which has wood blades with plastic coating like an Aeromatic. The Swift type certificate is available for viewing on the Swift Page, it lists all the approved props. The Aeromatic and the fixed pitch wood prop were all that was available in '46. -- Jim

Subject: Re: Paperwork Question
From: Terry McCartney <>
Hello Jim,
We missed you at Westover last month. I hope you can shed some light on a paperwork question I have. If airplane is equipped with O300-A as per the Piedmont Aviation Instructions (Swift Museum STC). What paperwork do you need to go from the McCauley DM prop to the Sensenich DR prop? I very much enjoy and always learn from your contributions to "The Swift." Thank You, Terry McCartney, NC3787K

There are several angles to approach this from. The Sensenich 74DR-1-62 prop is STC'ed, the STC being held by Rudolph Chalow of Newfield, NJ. Several years ago I tried to contact him and was unsuccessful. The Merlyn GW increase for the 145 allows the Sensenich prop at a lower pitch. I do not know the availability of the Merlyn STC right now. I suggest you contact Suzanne at Merlyn Products, they have a link off the Swift Home Page. The original type certificate lists the Sensenich M74-DR-1 (no pitch mentioned) for the C-125. Since the power is limited to 125 hp, it should be relatively easy to get a field approval for that prop on a 145/O-300. All prop field approvals have to go to FAA engineering now, so it may take a few months. Do you know an A&P IA that has a good working relationship with an FAA inspector? He could try for a 337 approval. I'll tell you what, I can't use your airplane, FAA regions, you know, but I will type up a 337 requesting a Sensenich 74-DR-1 on my N2431B. I have the prop and haven't gotten around to installing it. I'll let you know what happens. -- Jim

Subject: Re: New Prop
Hey Monty:
I bought a Sensenich DR74 prop that originally came from Mark Holliday's hangar.... I got it through Bill Shepherd because he knew I was really looking for one. I think it's a 58 pitch, but was wondering what your thoughts were on re-pitching it for a better cruise speed. I currently have one of the slowest Swifts around, even with the new engine. It climbs better than most to about 5000', but once I level off, I get left behind..... The current McCauley prop I have is great on climb out, but I can easily run it over redline and still have lots of throttle to go at cruise.... I think it's a 57, but it's also a clip tipped prop....

I would suggest you try it as is and see how you like it. One thing I might mention, with a 57" or 58" pitch, you have to cruise at 2600 or 2700 rpm to get any speed. Do you have an O-300 power chart? 2700 is permissible for cruise at lower manifold pressure. An easy way to remember is, an O-300 is a "48" engine, that is, a combination of rpm and manifold pressure which totals 48 is 75% power. Like 2400 rpm and 24 inches mp = 75%. or 2700 x 21 = 75% or 2600 x 22 = 75% or 2500 x 23 = 75%

Subject: Another Prop Question
Can you tell me how high the prop bolts should be torqued? Is it foot pounds or inch pounds? I hope to be able to put the prop on tomorrow (Saturday), so if you could get back to me with a quick response I'd appreciate it. Thanks much....Don

Per the Sensenich site: ( the 74DR is a 3/8 inch nut; 25 ft lb should work out fine. RECOMMENDED WRENCH TORQUE : 3/8 inch 23 to 25 lb-ft (280 to 300 lb-in) (31.6 to 33.9 newton-meters) 7/16 inch 40 to 45 lb-ft (480 to 540 lb-in) (54.2 to 61.0 newton-meters) 1/2 inch 60 to 65 lb-ft (720 to 780 lb-in) (81.3 to

Subject: Re: Swift prop
From: Steve Whittenberger <>
Steve Whittenberger in Daytona Beach again. Heard one the other day on a Swift that raised a few questions in my mind. A guy rebuilding a Swift said he was going to put a constant speed prop on a 145. - Can this be done?

The only "constant speed" for a 145 is the Aeromatic
- Is it advisable? [no]
- How difficult? [no, except they are getting hard to find]
- How expensive? [the last Aeromatics were quite expensive]
- Performance gained worth the cost? [no]
- If doable, what kind of performance can you expect?[an Aeromatic will get off the ground pretty good, cruise at about 120 mph and go about 135 mph wide open]
As you may be able to tell, I am not too much in favor of the Aeromatic prop. They are a product of the '40's and obsolete today. They had a good idea, if someone adapted some lightweight composite blades to the original type hub that were more efficient than the wood blades, they might have something. -- Jim Montague

PROPS AND PITCH... (010600)
Subject: Re: More Monty stuff !
From: Pete King <>
Hi, Jim,
Is there a Sensenich prop approved for the C-125? Or were they only approved for the C-145?

If you look at the original type certificate, which is posted on the Swift Home Page, you will see the Sensenich 74DR-1 listed. The use of that prop is a little more problematic on a 145. There is an STC listed, SA1-335, held by a Mr Chalow in NJ. Mr Chalow is non-available and I suspect he is no longer with us. Merlyn Products holds an STC for a GW increase to 1835 lb. with a 145 and it permits the use of either a McCauley or Sensenich prop. I don't know if Merlyn is selling that STC right now. I have applied for a field approval to install a 74DR-1-62 prop on my Swift, but haven't heard back from the FAA. I intend to apply for the STC when this chapter is over. -- Jim

Thanks for the reply. I had a 74-DR-1 - 62 on my first Swift -- 78247 -- a 145 -- was very pleased with it. Didn't realize / think you could run the same prop on a 125 -- less power-- especially on take off !! Believe the 62 was a cruise prop -- thought the extra power was needed to turn it up ! Regards, Pete

Yes, you can run the 74DR-1 at any pitch on a C-125 as long as it turns static rpm within the limits of the aircraft spec. Minimum static rpm for that prop is 2080 rpm. Yes, a 62 pitch is a 145 cruise prop, but a strong 125 might turn it fast enough to be legal. -- Jim

Subject: Re: GC-1A props w/C-90
What prop do you like on a GC-1A with a 90 ?

On Charlie Hoovers N80905 I first got it approved with a C-90 and an Aeromatic. He decided he wanted a fixed pitch prop, so I applied for and got a McCauley SCM approved. (I think it was a 71x54) I looked it up, it was a McCauley 1A105/SCM. Then he bought a Sensenich 72CKS6-54 (72 dia.) which he installed with a 1 1/2" spacer. I got that one approved too. He later went back to the McCauley, which he likes best. I rode with him a month ago or so and it performs very well. He has beat every 125 he has run against and also several 145's. -- Jim

I was rereading my earlier reply to Pete King in the last newsletter (regarding props). One thing I forgot to mention, the McCauley prop lists for about $3,000 and the Sensenich can be obtained for about half that. --Jim

From: Jim Montague <>
Subject: Sensenich 74DR-1-62 approved
As you folks may remember, several months ago the question came up regarding the use of a Sensenich 74DR-1-62 prop on a 145. The Sensenich 74DR-1-62 is STCed for the C-145, but the holder is non-available. Merlyn offers the option of a Sensenich prop on their 145 GW increase. I applied for a field approval last November to use that prop on my Swift with the O-300A. All prop field approvals have to go through FAA engineering now. Yesterday, I got the 337 returned with the magic stamp in Block 3. APPROVED! Well, it only took 3 months. I can supply copies if it will help anybody. -- Monty

Subject: Re: Sensenich prop
From: Mark Kadrich <>
Monty, What does this prop do for a O300C? Better climb or cruse? Did you sacrifice any performance? Mark Kadrich, 3243K

The DR series prop won't work on an O-300C (or D). The C and D have a smaller crankshaft flange. They need a DC series prop. The climb, like any fixed pitch, high pitched prop, is not usually too great. The cruise is usually pretty good with any Sensenich prop pitched over 60'. I had a 74DR-1-62 on N2334B and thought the performance was pretty good overall, but I never flew in the mountains. We are at the mercy of the FAA with the props we can use on the 145 hp Swifts. To get a prop approved, it has to limit the engine to 125 hp of output. A prop which would turn up 2700 rpm for takeoff would perform pretty good at high altitudes, but also would tend to overspeed under some conditions. That's life with a fixed pitch prop. -- Jim

I emailed Michael Muehlbauer of MT-Propeller, Entwicklung, GmbH. (That's in Germany, I think...) I asked him the following question: "in case you ever develop a constant speed propeller for a Continental O-300 I'd love to hear about it!" Here is Michael's reply...
From: "Michael Muehlbauer" <>
Subject: Continental O-300 engine
We have propellers in our product line, which can be installed on the Continental O-300 engine, but we have not made any vibration analysis so far, which means such a propeller is only available for the Experimental category at the moment. Both a 2-blade and a 3-blade electric constant speed propeller are available: Price of the 2-blade constant speed package: US$ 9,090.- Price of the 3-blade constant speed package: US$ 9,570.- Included in the package is the propeller, the spinner assy with integrated slip rings, the constant speed microprocessor equipped control unit P-120-U, the brush block assy with integrated RPM sensor, the wiring, a 2.2" size manifold pressure gauge and a 4 amps circuit breaker. This is a complete conversion kit from fixed to variable pitch constant speed. Both propellers are certified by the German LBA. So far we have only applied for the FAA approval of the 3-blade propeller. All prices are the export prices from factory, delivered out of Orlando, FL. Any news about new certifications and installations will by published on our website as soon as available. Our website is still developing and does unfortunately not yet display all information. Once again thank you & Best Regards Michael Muehlbauer, MT-Propeller Entwicklung GmbH, <>

So O-300 Swift owners, you aren't totally stuck with a fixed pitch prop if you are willing to to this route. I'd do it but I'm buying stock in "pampers" right now. Who will be the first to try one on their Swift???? (I'm great at spending other people's money, aren't I ???) The MT-Propeller web site address is:

From: Bud England <Dalswift1>
Jim: Cheers to you for your efforts to get an STC for the 74DR-1 on the C-145/O-300! Now tell me a little more about the C-145-2H, made to take the 2 position prop. I know Mark had a prop he was experimenting with but felt that it wasn't worthwhile due to weight. However, if my memory serves me correctly, there used to be a prop for this application called something like Flow-Thorp (I've probably really screwed up the spelling) that might due the trick. What I don't know is whether this was some old prop with fiber-glass blade, dangerous to try to use after all these years. The point is, I flat have already told you everything I know about the prop. With the # of -2H's around (thanks to Cessna) I'll bet there alot of others who would be interested in the supposed advantage of a climb/cruise prop. Anything you can tell me would be greatly appreciated. -- Bud

The only other prop I know of for the C-145-2H and O-300B is a hi-cruise Aeromatic. I have written about the Aeromatic several times in the past year or so. About the only thing I think is advantageous about that prop is you can lower the rpm in cruise for a quieter flight. There was a guy out west who was gonna start producing Aeromatics, but his web site has disappeared and I presume he has gone belly up. There was a company called Flo-Torp who made Aeromatic blades at one time, perhaps that is what you are thinking of. -- Jim

On to page three regarding Swift props...

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