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ACRO E-mail Archive Thread: [Acro] Re: Pitts S-1S questions - Here are the ...



                


Thread: [Acro] Re: Pitts S-1S questions - Here are the ...

Message: [Acro] Re: Pitts S-1S questions - Here are the REPLIES!

Follow-Up To: ACRO Email list (for List Members only)

From: "David Magaw" <dmagaw at att.net>

Date: Wed, 17 Oct 2001 02:54:27 UTC


Message:

  Thank you.  This is very good info for us pitts wanabes.
Dave
----- Original Message -----
From: <Klusmanp at aol.com>
To: <acro at gf24.de>
Sent: Tuesday, October 16, 2001 7:15 PM
Subject: [Acro] Pitts S-1S questions - Here are the REPLIES!


> As I have received no less than six requests from other members of the
Acro
> list to fwd replies to my Pitts S-1S questions, I have condensed the many
> replies I have received and now offer them to all on the mailing list.
>
> My apologies to anyone who replied to me in private and did not intend for
> their comments to be made public on the list. In the spirit of privacy I
will
> not include names with the comments.
>
> My thanks again for the almost overwhelming response to my questions! I
> receive mailings from another aircraft list and an automotive list. This
acro
> list is by far the most friendly and responsive list of the three.
>
>
>
>
> Below are my original questions and responses from one or more people.
>
> 1) A sport aviation article mentions that "Sparcraft" wings don't fly
quite
> as well as true "Pitts" wings. How significant is this? Is there an
> appreciable weight or strength difference?
>
> <<As far as Sparcraft wings I have not heard mention them flying
differently
> but there is a factor of strength. Sparcraft wings have a routed plywood
> rib as opposed to truss style built ribs in the pitts wings. There have
> been some problems with the Sparcraft ribs breaking. A good source of
> information for this would be the IAC technical tips manuals available
> through EAA. How hard the aircraft has been flown and how hard you plan on
> flying will play a factor in this also.>>
>
> <<<<All I do is aerobatic aircraft maintenance...  <snip>   ...sparcraft
> wings are o.k. , the spars are built the same as the factory , but the
ribs
> are 1/4 " routed out plywood instead of build up ribs , roll rate is a
little
> slower on  a sparcraft wing due to the freese ailerons and the large gaps
in
> the aileron wells>>
>
> <<Although many folks fly the Spartcraft wings they haven't always been as
> stout as the Pitts style wings.  Although all of them have pull block
> problems from time to time. >>
>
> <<Same airfoil as the Pitts S-1 but heavier because the ribs are solid.
> Weight is bad but if this is your first Pitts,  not the end of the
world.>>
>
> <<Unless you buy a factor Pitts, you have a slim chance
> you will be getting Pitts wings. Most are sparcraft.
> They are good wings, but however, are slightly heavier
> (so I am told. At out levels, it will not be
> noticable. Later on you can build you own set.>>
>
> <<Sparcraft wings are OK, not as light, but not many
> floks will know the difference.>>
>
>
> 2) Many planes have a flat pitched prop for good climb. These props have
the
> potential to over-rev the engine at full throttle. What is a good
> conservative TBO for an engine that has seen a lot of 3,000+ rpm
operation?
>
>
> <<With a fixed pitch prop you will over rev the engine. I have a 74-56 so
it
> runs about 3500 RPM max in the box. You may get varying responses on this
but
> the bottom line is that the RPM isnt as bad for the motor as high EGT or
CHT
> temps. You can burn a cylinder very quick at 2000 RPM if the CHT is too
high.
> My motor has over 700 hrs of Advanced acro and the compressions are all
over
> 78 and the oil analysis is better than my Aeronca. If you fly often enough
> the high RPMs shouldnt affect it too much but obviously bearings and some
> other rotating parts will wear out sooner than the 2000 hr TBO. I would
think
> my motor will go 1000-1100 hrs but Sportsman  type acro would yield
1400-1500
> hrs. Its a different story if the airplane sits for a long time between
> flights as the corrosion that builds up acts like sandpaper. If you fly
once
> a week or more often that would be ideal>>
>
> <<<<All I do is aerobatic aircraft maintenance... <snip> ...as for the
prop a
> 60" pitch works the best with a 180hp and your rpm's will still be 2900
> straight and level. all aerobatic engines should make it 1200hr.s even
with
> high compression pistions.>>
>
> <<800 hours is a common time to do a major overhaul on an over -revved
> engine.>>
>
> <<You cant have it all. If you want climb performance, you have to have a
> climb prop  and the engine will be operated above red line at times. My
> Pitts, at full power in level flight  will indicate 3300 rpm. >>
>
> <<Many people wind the Lycomings up to 3500 RPM without any apparent
damage
> to the engines or significant loss between overhauls.  That 800 or so RPM
> represents almost a 30% boost in horsepower which is nice to carry into a
> vertical.  High pitch, hi revving props are noisy and slow crosscounty but
> they do help while doing figures.>>
>
> <>
>
> <<3000 rpm will not hurt a TBO is the engine is/has
> been taken care of properly.>>
>
>
> 3) Do high-compression pistons reduce TBO?
>
> <<The high compression pistons will do a lot more to reduce TBO than high
> RPM. The increase in CHT and Oil Temps will reduce TBO due to cylinder
wear.
> I dont run them in my airplane but I wouldnt hesitate to throw them in.
Just
> understand the TBO may go down a couple of hundred hours as a result>>
>
> <<  Reaching TBO, you will probably get allot of different replies on this
> one. I have seen both sides of the story here. I know San Burges had a
> engine with countless overspeeds that went to TBO, but have also heard not
> to expect an acro engine to get past halfway to TBO. The two large
> variables here how hard the aircraft has been flown and how well it has
> been maintained. I would suggest contacting some of the better known acro
> engine builders,Lycon, Barret, Demars and get there opinion. They should
> also be able to give you some insight into the question of high
compression
> pistons.>>
>
> <<High compression pistons make if extremely difficult to hand prop a hot
> engine!>>
>
> << (Do high-compression pistons reduce TBO?) Not that I know of. Some
> certified engines (Lyc 0-320-D2A) are high compression engines and the TBO
is
> 2000 hours.  Heavy aerobatics will reduce TBO.>>
>
> <<(Do high-compression pistons reduce TBO?) Quite
> simply, yes.>>
>
> <<The higher compression the engine is, usually the
> lower the TBO is.>>
>
> 4) Any items of airframe stress and wear I should look for?
>
>
> <<The weakest part of my airplane is the fabric. Due to the propwash and g
> forces the tapes on the inside portions of the wings tend to come loose.
Many
> people never glued down their tapes and just doped them on. This is bad.
> After mine came loose I reglued them and switched to 3" from 2" wide and
no
> more problems. There is nothing worse than having to do fabric repair on a
> shiny new Pitts
>
> If you plan to only fly Sportsman or rec acro I wouldnt worry too much
about
> anything else. Once you start flying Advanced engine mounts, tapes, and
drag
> wires will start to go. They are generally very strong airplanes>>
>
> <<  Be sure to check wing attach brackets for cracks and any signs of the
> bolt
> hole being enlarged by movement. If the aircraft has spring type gear
> inspect the longerons around the gear attach VERY WELL. As I am sure you
> are discovering most S1S's being home builts there are endless variables
to
> deal with. I would suggest getting some with pitts knowledge to inspect
the
> aircraft.>>
>
> <<There are some stress points on the S-1S you should be aware of. The
lower
> wing, rear attach fitting and the upper longeron just forward of the
> instrument panel are 2 areas. Check the AD's or factory support. >>
>
> <<Some of the things that are likely to bite you and cost money are:
>
> Fabric and paint. If the fabric and paint are not in good shape walk away
> because it costs more to recover and paint than it does to put a new motor
> on AND it takes 6 months.
>
> Motor. Obviously you want to check the heck out of it, I'd want to get an
> oil sample, have a look at the oil screen, compression test etc. etc.
> nothing out of the ordinary for a good mechanic.
>
> Tubes etc. make sure there is close to zero rust. Once it starts to rust
its
> hard to control it. Note that rust on some of the fittings is no big deal,
> just change them but if the tubes in the back start to go its gonna be
> expensive. There are rear spar attach AD's that require inspection every
50
> hours but I've never heard of an S1 with a cracked rear spar attachment.
It
> happened on an S-2B and the entire line got the AD.
>
> The fuel tank in the S-1's is subject to cracking. Check the front and
rear
> of the tank to make sure there are no cracks. If it is cracked and has
been
> putty repaired it will cost many thousands of dollars to repair properly.
(I
> found this in my pre-purchase).
>
> The S-1s were modified early on to stiffen up the tail feathers. In
> particular they added under stab diagonal cross braces. Make sure your
plane
> has these as it's a rather important mod.
>
> The S-1's were also prone to tail wheel breakage. The tab at the bottom of
> the rudder post would come unwelded and let the tail wheel leaf springs go
> left or right for a run ride. The SB calls for a small triangular tang to
be
> welded behind the tab. Mine broke on my 5th landing. No problem but a pain
> to get fixed and on a narrow runway it could have been costly.
>
> Check the dates on all the rubber parts in the plane. All the hoses etc.
and
> especially the flop tube in the gas tank. If its more than say 8 years old
> that rubber is getting hard and probably needs changing. A complete hose
> change in a Pitts is many thousands of dollars because of the inverted oil
> system which adds a bunch more hoses to the system.>>
>
> <<First, check out the service bulletins.
> One major one you will hear alot about is the rear
> attach point. Also, go to www.musclebiplane.org and
> then to the maintainence area. Excellent photographs
> and suggestions for stuff to look at. If you are going
> to get into tailslides later on, you will be advised
> to get the rear tail struts. Ckeck the motor mounts.
> Also, find out if has EVER been ground looped or even
> just "dragged a wing (common)". Even though it may be
> just cosmetic dammage, there is a signifigat moment
> out there and it puts alot of stress on the wind atach
> points AND the upper cabine attach points. Check
> carefully.Also, check the cut out area around the
> bungees. Sometimes they will start to wear the
> protction around the bungees and will lead to an
> earily replacement.>>
>
> <<Check the longerons, especially by the landing gear.
> If you are able to, check the H-tube (by the horizontal
> stab).>>
>
>
> 5) I've encountered many different engine types: Ellison pressure carb,
fuel
> injected, and some carburated engines converted by adding a Bendix fuel
> injection system. Is there a big operational difference between pressure
> carb. and fuel injected?
>
>
> <<Stay away from the Ellisson TBI lke the plague. I have it on my airplane
> and its the worst. Already been overhauled twice in 500 hrs at a total
cost
> of $1500.
>
> Do whatever you can to find a fuel injected airplane but if not the
pressure
> carb is good>>
>
> <<All I do is aerobatic aircraft maintenance... <snip> ...Ellision
throttle
> bodies suck , allways a probelm , as the same for pressure carbs . Fuel
> injection is the only way to go>>
>
> <<Bendix or AirPower fuel injection systems are now the most popular.
> Pressure carbs are expensive, difficult to keep repaired and designed for
> much larger engines so they give problems.  Some folks have had no
problems
> with the throttle body Ellisons.  Others have had trouble.  It may do with
> cleanliness.  I don't know.  The only throttle body that has ever had any
> success in aerobatic circles is the Ellison.  Overall it is hard to beat
the
> Bendix or its successor fuel injection.>>
>
> <<The Bendix pressure carb is excellent if it is well cared for. If you
find
> a Pitts with one, make sure it has been recently overhauled and the NEW
> gaskets installed. If you have the replace the OLD gaskets  the bill is
$1400
> dollars. The overhaul of a PS-5C with the NEW gaskets already installed in
> about $150. Experience talking>>
>
> <>
>
> <<On the carb vs FI,   the only pressure carb is the PS5C.  It performs
OK,
> but is quite expensive to have OH'd.
> I have one on a O320 pitts.    Not many know how to work on that carb so
its
> important to find a shop that can work on them.   Bendix FI is probably
best,
> but it is not cheap to OH either.
>  The Ellison  TBI is the lowest cost to buy and to OH, but it can be very
> frustrating to get it working properly as it is VERY sensitive to the air
box
> and airflow into the TBI.>>
>
> <<A fuel injected engine is better overall, whether it
> is from the factory or from Airflow Performance.>>
>
>
> 6) Do I need to look for a specific aerobatic crankshaft on the engine?
>
> <<As far as the crank that depends on what kind of acro you will be doing.
> With a metal prop regardless of wether you have an acro crank or regular
you
> will break a crank when you do a lot of snaps. I run a composite prop on
my
> std crank and no problems and I do 20-30 snaps a flight. My buddy cracked
a
> crank on his S-2B after 300 hrs with a metal prop>>
>
> <<Be certain you have the aerobatic crankshaft or else don't ever do snap
> rolls, tail-slides, flat spins and gyroscopics.  You might "toss your
prop".>>
>
> <<If possible, make sure it has the solid flange
> crankshaft.If not you will be doing frequent
> inspections and will always have the worries
> accompaning it. If you can get an wooden OR composit
> prop, it will be less wear on the flange.>>
>
> <<On the crank, best is to have the aerobatic crank. These don't have
holes
> in the flange. If you have a CS with holes in the flange, then you must
> inspect it each 25 hours per   AD and/or Lyc SB if you are flying any
acro.>>
>
>
> 7) What inspection interval does the prop need?
>
> <<A  fixed pitch prop is good for only 800 hours or so according to
> Sensenich. Don't get one that has been re-pitched or damaged -ever.>>
>
>
>
> 8) How much is a composite prop and where do I get one?
>
> <<A commposite prop is nominally an advantage if you plan to do a lot of
> gyroscopic maneuvers such as tumbles, agressive snaps etc.  It reduces the
> precession forces on the crankshaft.  Otherwise it may not be worth the
> considerable extra price over a fixed pitch.  One advantage of a fixed
pitch
> is that you can wind up the engine considerably over the 2700 rpm that is
> imposed by a controlled pitch prop.>>
>
> <<Composite - Performance Propeller
> Wood - Sensenich>>
>
>
>
> 9) Other comments:
>
> <<What made you decide on an S rather than a T?
> While the S is a good aircraft the T will outperform the S.
> Now that I've said that you will understand my bias when I tell you I have
a
> S1t that I'm selling.  Its a factory built aircraft with the AEIO 360.
About
> 600hrs on the engine and 930 TTAF.  Was built in 1986 and and recovered
about
> 94.  With out the log books in front of me not real sure of exact
numbers.>>
>
>
> <<You do want to get a good pre buy from someone that knows Pitts though
as
> many builder problems will cause headaches later on>>
>
> <<Hi Paul and welcome to the world of aerobatics. As a former owner of a
> Pitts S1S I can recommend a very reliable source for all of your
questions.
> Call Mike Mays at So. Aerobatics in West Palm Beach. He has been working
on
> aerobatic airplanes (especially Pitts) for many many years. Mike likes to
> talk and he can answer all of your question. He seems to be tapped into a
> network of the Pitts market as well and can help you locate just the right
> airplane for your needs. Yes, he will make a buck on the transaction, but
in
> the end, you will thank him for taking your money and steering you onto
the
> right (safe) airplane.
>
> By the way, every one of us thought when we started that we only wanted to
do
> recreational aerobatics. I am sure that some people do stick to that level
of
> the game, but most who I have known have gotten totally involved. It is a
> real head rush to compete.>>
>
> <<Don't look at anything. Find the best Pitts machanic in the area and pay
> him to find you a good Pitts. Then plan on spending $3000 to $5000 more to
do
> what needs to be done. You haven't got a clue on what to look for and you
> might get hurt if you try. I have owned a few aerobatic airplanes and
worked
> on many more. I have seen things flying that you would say could not fly.
> Most Pitts ' with sparcraft wings are not S1Ss. Thye are S1Cs made to look
> like S1Ss but there is much more to it then that. Just don't buy one. That
is
> why they are so cheap. $30,000 to $35,000 is a good price for an S1S. You
> won't get 1000 hours out of any aerobatic airplane. Find a good
machanic.>>
>
> <<Paul,
>     I do not claim to be an expert but hopefully I can give you some
> information that will be helpful. First of all how much tail wheel time do
> you have. I you do not have allot I would strongly suggest getting tail
> wheel proficient in a another type of aircraft, cub,champ,citabria ect.
> Then practice flying a citabria or decathlon from the back set. When
> comfortable with this the transitioning to a pitts is not a big deal.
>
>     Another good source for information is the Muscle Biplane web site, I
> think the address is <musclebiplane.org>.
> >>
>
> <>
>
> <<All I do is aerobatic aircraft maintenance , and the best advise I can
give
> you is get a good prepurchase from someone who knows the wear points on an
> aerobatic plane . Whatever area you are looking at one , there should be
> someone around who can check it out for you. <snip>    MAKE sure you are
> buying a S-1-S and not an S-1-C , the S has a longer fuselage and more
inside
> room. <snip>     get one with 180hp or better.>>
>
> <<Get some complete spin training before you start fooling around in your
> Pitts.  there are many places you can get this training.  Since I don't
know
> where you live I will give you a few names of reliable sources.  I may
> overlook a few.  That doesn't mean I don't approve, just forgot or am
> ignorant.
>
> Bill Finagin (Annapolis MD)
> H-R Aviation (LaPorte, TX)
> John  Walkup  (Chandler, AZ)
> Michael Church (Sunrise Aviation at Orange Co. Airport)
> Don Hart (Hart-Aire at Long Beach, CA)
> Ken Erickson  (Sean Tucker's School at Salinas, CA.)
> Dick Rihn (Attitude Aviation at Livermore, CA.)
>
> The Pitts is a pussycat when you know how to fly it.  It is a tiger until
> then.  Get trained by experts.  It will be money well spent.>>
>
> <<Find an A&P with Pitts experience and have him/her go over the plane IN
> GREAT DETAIL. Dont get overly concerned about HP. At your stage there is
> little to be gained by having an 0-360 instead of an 0-320>>
>
> <<My mechanic has been Ray Williams near Nashville TN. He is w/o a doubt
the
> best Pitts mechanic anywhere. Ask some of the aerobatic people and they
will
> know of his rep.>>
>
> <<Paul, I sent a similar email out to this group a couple of years ago and
the
> advice I got was invaluable. I purchased a Pitts S-1T about 2 years ago in
> Florida and my use of a very good knowledgeable Pitts mechanic saved me
10's
> of thousands of dollars.>>
>
> <>
>
> <>
>
>


                


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