MONTY THE ANSWER MAN ARCHIVE...
From the Yahoo! Globe Temco Swift Club... a "member" asked:
Is anyone an expert on Beech-Roby props, or can steer me to where I can
find information on these? I recall once seeing a Swift with a 125 hp
Cont. having a Beech-Roby adjustable prop. I know they were commonly available
for 65 & 85 hp Cont., but what about the larger engines? I recall
a Mooney Mite owner who swore by the Beech-Roby on his 65 HP Lycoming.
If you have an anecdote to share, please do.
Um, does having a couple hundred hours behind Beech-Roby props, (and lived!)
make me an "expert"? The C-125 version requires a C-125-1 (spline shaft
engine) One guy claims he has a flange shaft model. Fine, he has the only
one in existence! They are terrible props.* (*Does that qualify me for
membership in the Richard Collins Club? ) I had an 85hp Swift that had
a Beech-Roby which performed quite well. When I bought the airplane, the
engine or prop seemed rough. I overhauled the engine and sent the prop
out for overhaul. The prop shop reported I was lucky, because one blade
was cracked half way around the ferrule, and would have departed soon.
My friend had a brand new Beech-Roby and the hub cracked at about 200
hours. Other Beech props with Univair blades have a 5 year AD note. Get
the picture? High maintenance, short TBO. Performance is not too bad,
but you must keep the rpm down. I too flew a Mooney Mite and it performed
well with the Beech-Roby. Our local prop shop has refused to work on them
in recent years, because of the liability laws.
The Beech-Roby and Aeromatic
had similar blades. Thick, wood, inefficient, with steel leading edges.
A friend had an Aeromatic and always bragged about being able to get 2700
rpm on takeoff. My Sensenich got 2200 rpm. One day we lined up side-by-side
and took off. I was off and had the gear up and he was still rolling.
He was tuning 2700 rpm all right, but I was getting more effective thrust.
The Beech-Roby was most effective on low rpm engines. The 65 hp Continental
turned 2300 max. and cruised at 2150. The Aeromatic is similar, it works
good on a Warner radial where the max. rpm is just over 2000 rpm. The
advantage to a controllable is to be able to turn the rpm UP, which is
just where these props DON'T work. With the high maintenance and possibility
of catastrophic failure that is why I don't like these props.
Steve Wilson adds...
These wood propellers are dated. Monty is right! They were not great performance
wise on the Swift, when they were new. Today the risk of a catastrophic
failure really puts their viability in question. You have to think, why
would you purposely purchase something that has a history of frequent
expensive maintenance, questionable reliability, and poor performance?
Yes, wooden props are smooth because they absorb a lot of vibration. Yes,
the pseudo-constant speed nature of the Aero-Matic is not as tiring as
a metal propeller on a long X/C. But the overriding risk attendant to
an instantaneous in-flight failure is not worth those small advantages
(if they are advantages at all). My suggestion is to stick with what is
currently available in fixed pitch metal propellers for the small TCM
engines. Everything is a compromise; however, chosen wisely the fixed
pitch metal propellers give the best performance now available in takeoff,
climb, and cruise.
O-300 ENGINES AND PROPS.
MONTY SAYS GO SENSENICH !!!
From: Dennis Mee (firstname.lastname@example.org)
Subject: Re: N3812K
I just came across an O300D I can get everything I need to make it work
except for a prop I guess that could be a problem without changing the
crank. I really don't need a vacuum pump since this will be a VFR restoration
so I'll keep looking. I think it will be a while before I'm ready for
an engine anyway. After checking the 1C172/EM propeller type certificate
I see that for O300 series up to 145hp and 2700 RPM -"from a vibration
standpoint" the minimum Dia is 70 inches so the 74.5 must be a recommended
minimum limit for overhaul. Thanks again for the info, Dennis Mee
I have gotten several O-300D's field approved both with the McCauley EM
series prop, and the Sensenich DC series. I would suggest you look for
a Sensenich prop. I got a Sensenich approved a year or so ago. The Sensenich
will outperform that EM McCauley. An O-300D with a Sensenich 74DC-1-60
will perform very good. BTW - that prop was used on a few 172's (with
a lesser pitch!) but was commonly used on the Beech Musketeer with the
TCM IO-346 engine.
ONE MORE QUESTION FROM DENNIS...
From: Dennis Mee (email@example.com)
Subject: Re: EM 7653 Prop
I have located a McCauley EM7653 prop that would work fine on the O300D,
but it would have to be re-pitched to 59 or whatever would be best. The
Swift type cert says 73" max dia for the 125 engine and the Swift O300-A
STC shows a DM7359, the prop shop says the EM76 can only be cut to 74.5"
Min. Have you had any field approvals with the larger dia props? I'd hate
to by it and have it cut that short , I hear the EM props are hard to
find. What are you thoughts?
I have had an EM reworked to a 74x59 and gotten it field approved, I think
the actual dia. may have been 74.5, but I'm not sure about that. The first
time I had it done the prop shop balked, asking "whose STC are you doing
this on"? I answered, "mine". Because I had the prior approval. I don't
think those EM props are hard to get. A much better prop is the Sensenich
74DC series prop. I think you should use a 7653 prop. It will really get
off good. It is actually non-approvable, but evidently somebody slipped
up. A 74 inch dia. prop is generally considered max. for a Swift. This
goes into the Part 23 certification requirements, where with a flat tire
and a flat strut there must be (9?) inches of clearance in the level flight
attitude. I guess I will re-read that part again. I used to keep a 76
x 53 prop around, and when I wanted to go grass strip hopping, I would
put it on. It really took off great, and didn't cruise too bad, if you
didn't mind cruising at 2700 rpm. Some guys have gotten 76 inch props
approved on 210's, either the regulation has changed or yardsticks are
shrinking! -- Jim
What is the proper position for a fixed pitch prop on a C-145-2? What
is your recommendation for best climb pitch? Best Cruise?
I have always put the TE
of #1 blade on the t/c mark of the crankshaft flange. This has usually
given smooth operation, as well as being the comfortable position for
hand propping. Cessna came out with a bulletin dated 7-8-53 which had
an illustration showing the t/c mark aligned vertically with the split
in the crankcase, and the c/l of #1 blade at the 11:00 position (looking
at it from the front; the first bolt hole being 10:30) I think the way
I do it is the same as what they're saying, except 180 deg different (which
should make no difference)
Best pitch depends. I had
a 62" on N2334B, and it cruised good, and climbed good too, the dia. was
72" I have a 73x59 on 31B and it climbs good, but I'm not too happy with
the speed, at 24" it turns 2600 rpm, but I like to run 2500which only
indicates about 135 mph. I like the higher pitch because it burns less
gas & is quieter in cruise. I just re-installed my McCauley 73x59
and am going to have the Sensenich re-pitched to 62". This prop at 59"
of pitch turns 2800-2850 rpm full throttle level at 2000' (I have a strong
engine, they won't all do that) Also, the tip chord on the prop can't
be "full dimension"- it has to be narrowed to near the repair limit before
the prop will turn up. I like round tips on a McCauley, they will run
pretty close to a Sensenich that way. (read my article in the "Vintage
Airplane" from a couple months ago) In high country you may want less
pitch and more rpm. -- Jim
Bob McKay (firstname.lastname@example.org) writes:
I was interested in your information in the latest swift news letter.
I had prop strike recently and the crank was cracked. The 145-2 is being
totally rebuilt at this time. I have a A170/DM7261 prop, and a A170/DM7458.
I am wondering if these can be used with this engine. Some of the prop
shops have told me that I cant use the 72 prop on the 145
engine. Is there a way to use it legally?. If I use the 74 prop
will it work out ok? I will be flying a lot of the time in the summer
at high density altitudes in Nevada in the Reno area.
I believe as far as the prop mfg specs go it can be shortened to 71.5"
dia. The Swift Assn. STC for the 145 states 73" dia. min. I don't know
what STC you have, but I see no problem with 72" - although at high alt.
you probably want the most dia. and least pitch possible. -- Jim
From: Steve Roth (StevenRoth@aol.com)
My Swift with O-300A has a McCauley DM74 prop. The paper work says at
restoration it was repitched from 58 to 63 then back to 58. I talked with
the restorers and they said that at 63 the climb was sluggish on
a warm day with two big fellas in it so they repitched it back to
On my flight from TX to
FL I could only get 100K cruise. I suspect that the prop could have more
pitch but how much? I talked with some local Washington, D.C. Swifters
and got various answers. I have not talked to many O-300A owners yet to
get their opinion on prop pitch so if you have some to refer me to send
me their e-mail addresses. I operate off of hard surface and usually long
runways (2600 ft or more). I am looking for fastest cruise and good climb
(500 FPM) at full gross. Any ideas?
Is it an actual 74" dia? The Swift Assn STC calls for a 1A170/DM7359 thats
73" dia, 59" pitch. My experience is that, the tips have to be reduced
either diameter, or chord width, to turn up adequate RPM for takeoff.
I have a 73x59 McCauley on my Swift right now, and the speed is about
140 mph ias at 24"x 2600 and a little over 130 mph ias at 23" x 2500.
If the pitch is over 60", rounded tips help unload it enough to turn up
for takeoff. I think my airplane has good takeoff and climb. Local elevations
are typically 1000 msl. I also have a Sensenich M74DR-1-59 (74 less 1
inch, in other words 73" dia.) which turns up a little too much RPM, its
been shaved down to the repair limit. My plan for that prop is to repitch
it to a 62".
I would suggest you borrow
a cut down McCauley from someone and try it. If you can't arrange that,
get a prop shop to rework yours to a 7359, and as long as you're at it,
get the tips rounded. -- Jim
INDEXING PROPS... (4499)
From: Bud England <Dalswift1@aol.com>
Please ask Jim (or anybody who could help): How do you index the prop
on a C125/145? TCM factory rep has no info. -- Bud
This is another item which is covered in a Swift Publication. "Maintenance
and Operation Information for the Swift" - published about 1987 and available
from Swift Parts. Prop indexing - hmmm....pg. 62 it quotes...me. Simply
put, align the trailing edge of one blade with the TDC mark on the crankshaft
flange. Cessna published a letter back in the 170 days which gives a different
index position. It might work for the 76" dia. props on a 170/172, but
it doesn't work on a Swift. -- Jim
Subject: Re: Swift Props
From: Dave Jewell <email@example.com>
I wonder if you would mind e-mailing me your phone number, or if you can
give me a call regarding the Univair controllable pitch prop, with F200H
hub and E-7 blades. I have read with interest your page on the web site
regarding the Univair propellers. I now have an Aeromatic prop and have
the opportunity to purchase the prop I have mentioned above. I would like
your thoughts on this. -- Dave
No problem. My phone # is 651-770-5069. It's on the Swift site, don't
you look at the Swift Home Page? Look at "Swifts by Serial Number" - Denis
has all my numbers and mailing addresses there. (also 2 pictures of me
now!) The Aeromatic might work for a while, but it always seems like they
need overhaul in a very short TBO, and there is no one that I know of
that works on them anymore. Actually, I was told of one shop that does
overhaul them, but spending $3,500.00 every 200 hours does not appeal
to me, so I just dismissed any information about the Aeromatics. Also,
they are SLOW. They get off the ground pretty good, but don't count on
over 120 mph in cruise. A long story shortened here - I had a Sensenich
M74DR-1-62 on a 145 hp Swift. Full throttle at 2000' MSL indicated about
165 mph. Switching to my Aeromatic full throttle at 2000' MSL indicated
135 mph. (this was done within an hour) If you still want to use the Aeromatic,
call me anytime, but 5 PM CST might be best. I would kind of like to have
an Aeromatic for display purposes on N2460B (Editor's note: the last Swift
ever built which Jim is restoring.) - all the late Temcos had them as
original equipment. But I wouldn't want to use one on an airplane that
I was going to use for cross-country flying. -- Jim
IN NEED OF A CONSTANT
SPEED PROPELLER... (8599)
From: Fernando Guerra <firstname.lastname@example.org>
Subject: Answer to your message to Fernando Guerra
I was very satisfied with your answer, I've a SWIFT since 1984. That is
my airshow plane. My plane was completely rebuilt by myself. I´ve
put a 145 HP Continental engine and a smoke system which I' ve projected.
Exactly as you said, my aircraft serial number is 2180. This plane was
exported to Uruguay after built and I' ve bought it on 1984. I think my
plane is nowadays a very good machine, with a fantastic performance to
the utility power it has. I've real need of a constant speed propeller,
I use a Mc' Cauley 76x53 a little bit more open, but the engine turns
very high performing aerobatics.I' haven't got a better solution to this
problem yet and I don't like very much the idea of put a heavier engine.
I will be very grateful if you can tell me about the solutions you and
your friends have improved in their planes in North America. Thanks to
your attention, -- Fernando Guerra
Actually, using a 76x53 prop is something I tried years ago, those of
you who read all my stuff on aerobatics you may recall I mentioned that.
It turns a little high rpm, but a good O-300 can cope with that. I feel
that is his best solution. A 210 Cont.and c/s prop will add close to 100
lbs of wt. Some guys use Lycomings thinking the 4 cyl. engines are lighter,
they are about the same. I assume he has a 1A170DM7653 prop, a 1C172MDM7652
propeller may work slightly better. That prop can be reworked to the "Jet-Flow"
profile and it will perform even better. It can be shortened to 74.5 inches
if need be. But for airshows he probably wants the extra noise of the
76" dia. There is no US made constant speed prop for the O-300/145. Hoffman
makes a prop in Germany which might work, but I no nothing about it. The
Aeromatic propeller is a true constant speed but it is very inefficient
due to the thick wood blades. 1940s technology, no good by today's standards.
There are a few Beech-Roby controllable props around. Same thing. There
is a McCauley controllable prop for the C-145-2H and O-300B, very heavy,
60 lbs. and not very efficient. For airshow aerobatics, a 76x53 fixed
pitch prop could be used. That is not a prop allowed on the standard type
certificate. (too much dia., not enough pitch) It will turn 3000 rpm under
some conditions. -- Jim
to page two regarding Swift props...