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Posted: Sat Feb 08, 2003 2:06 am
by zero.one.victor
I did see some nice stuff on the newest Swift over at DP. It's a 145 horse,converted to sticks and dual throttles. The previous owner is an ex-militairy pilot and did a lot of formation work in it. Some real nice fabrication work on the LH throttle linkage,but talk about getting carried away.
It also has an oil cooler arrangement,a big T-shaped housing replaces the oil screen,the oil lines to/from the cooler connect to this fitting.The screen itself screws into this housing also. I believe that it is the same part as shown in the C-145 IPC. I've never seen this set-up on a 170,but have heard a lot of 170er's express interest in adding an oil cooler. Maybe they're all in the hands of those Swifters. Greedy buggers!
Eric
Posted: Sun Feb 09, 2003 4:21 am
by N170BP
funseventy wrote:I'm sorry Bela. I didn't mean that you thought that. I just meant in General I love my 170. The swift I raced was almost all original except the C-125 was replaced with a O-300D and it was really light. It fit into a neat class, 108-149hp. Not many airplanes in there will compete witha swift. Including Take-off and Climb over a 60 mile course we won with 153mph. It was fun.
Once again Bela, I never wanted to offend you.
Kelly
I'm not offended, just a bit frustrated.... I'm a relatively new
170 owner.... And the guys at the airport (hangar flying sessions)
say to do one thing with the wing to go faster. Some other guys
say to do the opposite thing with the wing to go faster. Still other
guys say "leave it alone, pour gas in it and go fly it".
I'm inclined to go along with the latter crowd after all's been said
and done, but for my own edificdation, I'd still like to know how
wing incidence effects cruise speed.
I understand that the folks at Cessna probably spent a good amount
of time fussing with all this stuff until they found what they thought
was the best compromise between cruise speed & takeoff/landing
performance as well as overall handling qualities.
Another thought I've had, is I know the wings have been off of my
airplane (it was wrecked 36+ years ago). I can only hope whomever
put the thing back together got it right with repsect to the wing incidence/
rigging. Does anyone know what the incidence is supposed to be
(factory setting)? I'd like to somehow verify that I've at least got the
thing set up the way Cessna says it should be....
Bela P. Havasreti
'54 C-170B N170BP
Posted: Sun Feb 09, 2003 8:35 am
by FredM
The design feature you have been talking about has a name. It's longitudinal dihedral angle. It's function is to provide stability and is a safety feature. It provides stability around the lateral axis. If you were to decrease the difference in the angle between the tail plane and the wing, it would only give you a very small increase in speed. Considering it would also make your plane less stable and eliminate a designed safety feature I would not consider making such an adjustment. I can only imagine what my insurance company would say If I had an accident and the insurance company found out. Besides there are many other legal ways to increase your speed.
Do a google search for ( longitudinal dihedral angle ) and I am sure you will find enough information to answer any other questions you might have, and then some. Before assuming your plane may have a problem I would compare it's flight characteristics to one that hasn't had the wings adjusted. If it's lateral stability is the same during stall recovery and descents then I would assume there isn't a problem. My motto has always been " if it ain't broke don't fix it"
Hope this has been some help...
Posted: Mon Feb 10, 2003 4:11 am
by N170BP
FredM wrote:The design feature you have been talking about has a name. It's longitudinal dihedral angle. It's function is to provide stability and is a safety feature. It provides stability around the lateral axis. If you were to decrease the difference in the angle between the tail plane and the wing, it would only give you a very small increase in speed. Considering it would also make your plane less stable and eliminate a designed safety feature I would not consider making such an adjustment. I can only imagine what my insurance company would say If I had an accident and the insurance company found out. Besides there are many other legal ways to increase your speed.
Do a google search for ( longitudinal dihedral angle ) and I am sure you will find enough information to answer any other questions you might have, and then some. Before assuming your plane may have a problem I would compare it's flight characteristics to one that hasn't had the wings adjusted. If it's lateral stability is the same during stall recovery and descents then I would assume there isn't a problem. My motto has always been " if it ain't broke don't fix it"
Hope this has been some help...
Thank you for your informative post Fred. This is the kind of
guidance/answer I was looking for.... I'll do a search on longitudinal
dihedral angle and see if I can learn myself a thing or two.
Bela P. Havasreti
'54 C-170B N170BP
Posted: Mon Feb 10, 2003 4:16 am
by N170BP
zero.one.victor wrote:There are now eight,count 'em eight,Swifts based at Diamond Point ,a small airpark just west of Port Townsend. I think it's a desease endemic to the area.I know most of them guys. Swifts are really cool. There are no 2 of the 8 alike--there are a 200 horse Lycoming,a 180 horse Lycoming,3 145 Cont's,2 125 Cont's,and a 150 Lyc with a c/s prop! Swifters are even more fanatical than us Cessna owners are. For the kind of money some of these guys have in their Swifts,they could buy RV's and go really fast.But they wouldn't be near as cool.....
Bela,I know why you want more speed outa yer 170. You ain't ever gonna keep up with that Skywagon crowd.....you just need to meet more 170er's to fly with!
Eric
Eric, I've given up on trying to keep up with that 180 crowd! (you
know who they are....). The only thing that I can hold my own on
with those bunch is my liquor....
Bela P. Havasreti
'54 C-170B N170BP
PS: While I was shopping for a 170, I was actively looking
at Swifts too.... Always have/had a soft spot in my heart
for the looks of a Swift....
Posted: Mon Feb 10, 2003 5:42 am
by zero.one.victor
After that comment,Bela,I'll be looking for the big pile of empties under Zero-bravo-papa at the Evergreen,er McMinnville,er NWAAC fly-in this summer! Keeping up with their drinkin' might be harder than keepin' up with their airspeed!
Eric
Posted: Mon Feb 10, 2003 6:35 am
by N170BP
Ha ha! Naw, the empties belong underneath
Gnarly Dude (aka the garbage scow....).
Bein's how it'll be our 1st year at McMinnville, I think we'll
go easy on the locals and dispose of our empties properly.
Gotta ease new folk into the antics of "The Bruise Group" (tm)
Bela P. Havasreti
'54 C-170B N170BP
Posted: Mon Feb 10, 2003 4:08 pm
by funseventy
Bela,
I'm glad to hear we are still friends. As for the factory setting of the incidence, it should be set in the middle of the excentrics. After doing that you should fly it and see if it flies level. If it doesn't you would start "washing in" lift to the heavy wing. Washing in really means increasing the angle of incidence. If that isn't enough then you start adjusting the other wing. This design feature was to make up for manufacturing inconsistences and are meant to be used, so ther are no insurance problems to worry about. As I mentioned previously the amount of cahnge you'll see is hardly enough to risk screwing up a straight flying airplane. Remember how your airplane looks when flying, real tail high? If you raise the trailing edge of the wing you wing really lower the tail at cruise making it more strealined. That's the paperback version. Kelly
Posted: Mon Feb 10, 2003 9:03 pm
by N170BP
Thanks Kelly. I'll have a look at where the eccentrics are,
and if they're anywhere near the middle, I think I'll just
leave them alone. The airplane flies straight & level, hands
off, so like someone else posted, if it ain't broken.....
Bela P. Havasreti
'54 C-170B N170BP
Posted: Mon Feb 24, 2003 2:37 pm
by GAHorn
N170BP wrote:This leads me to ask the question;
Has anyone adjusted their wing trailing edge eccentric bolts to move
the wing trailing edges down as far as they'll go and noticed
any improvement in cruise speed?
I was thinking about trying this.... Maybe move them both
down as far as they'll go, test fly the thing, and if it flys crooked,
move the offending wing back up bit by bit until she flys hands-off
again.
Is there any reason why I shouldn't do this?
Bela P. Havasreti
'54 C-170B N170BP
Cessna designed the wing angle of incidence to be correct for the airplane to be at it's COG at 2,000 lbs, with the elevator faired. The eccentric bushings at the rear spar are only for "levelling" a heavy wing due to repair and/or mfr'g tolerances. Ideally they would both be in their neutral positions. It's a waste of time attempting performance gains by any tweaking of the bushings. Not only will any gains be impossible to measure, they'll also be temporary when your CG shifts due to fuel burn-off on your idealized flight of fancy. (This is sort of like the old adage about "measuring it with a micrometer, marking it with a grease-pencil, and cutting it with a hatchet.")
Posted: Mon Feb 24, 2003 2:39 pm
by GAHorn
gahorn wrote:N170BP wrote:This leads me to ask the question;
Has anyone adjusted their wing trailing edge eccentric bolts to move
the wing trailing edges down as far as they'll go and noticed
any improvement in cruise speed?
I was thinking about trying this.... Maybe move them both
down as far as they'll go, test fly the thing, and if it flys crooked,
move the offending wing back up bit by bit until she flys hands-off
again.
Is there any reason why I shouldn't do this?
Bela P. Havasreti
'54 C-170B N170BP
Cessna designed the wing angle of incidence to be correct for the airplane to be at it's COG at 2,000 lbs, with the elevator faired. The eccentric bushings at the rear spar are only for "levelling" a heavy wing due to repair and/or mfr'g tolerances. Ideally they would both be in their neutral positions. It's a waste of time attempting performance gains by any tweaking of the bushings. Not only will any gains be so small as to be impossible to measure, they'll also be temporary when your CG shifts due to fuel burn-off on your idealized flight of fancy. (This is sort of like the old adage about "measuring it with a micrometer, marking it with a grease-pencil, and cutting it with a hatchet.")