Flaps

Submitted by Anonymous on

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From: <N295P [at] aol.com>
Subject: Re: Flaps
Date: Tue, 8 Jun 1999 20:29:04 EDT
To: <brakes1 [at] bentonrea.com>, <lancair.list [at] olsusa.com>

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FLAPS:



Addendum to my letter yesterday. I was incorrect on the description of the

IV's flap cylinder stops, it has been a while since I rigged them. Here's how

I did mine.



The flap actuator cylinder (HC-09) is a reduced travel actuator, designed to

be the UP and DOWN stop at the end of it's range of travel, each way. The

center flap bellcrank (make sure you have the new reinforced one), is set to

travel an equal amount on either side of centerline, as per page 21-15. At

the UP position, I added a 1/2" or so, rigging wood block to stop the

bellcrank's travel, roughly keeping the top (long) arm of the bellcrank

parallel to the front member of the MG box. The block touches the cylindrical

end of the long arm of the bellcrank at full UP and is instant glued to the

backside of the front MG box member. The flap pushrods going out to the wings

can then be final adjusted with no fear of going further. Have a helper or

use duct tape to place the flaps in their full UP position, firmly against

the forward ends of the flap tracks, while you adjust the pushrods to the

center bellcrank.



The actuator can then be installed, set at it's full extension, with the rod

end about 3/4 screwed onto the shaft of the actuator and installed to the

bellcrank. The actuator at full extension then defines it's rear bracket

attach point. If all is well, the UP stop is the actuator at full extension,

with the DOWN stop the actuator fully retracted. You should have 1/8" left of

travel at the rear end of the flap tracks on the wings, in full DOWN, thereby

insuring that nothing is loaded in compression. You cycle the flaps a few

times, knock off the wood block; then recheck that at full UP, the wing

pushrod length is snug to the bellcrank, not in a forced position. Tighten

all the nuts, checknuts. A bit of grease on the bearings and years of good

service will follow. Do make sure that the pushrods coming in from the wings

have clearance for their full range of motion, especially where they

penetrate the fuselage. I had to enlarge the opening slightly on one side.



Finally, there is a service bulletin requiring the rear actuator attach

bracket to be inspected for cracks. Since the hydraulic shaft is retracted in

the DOWN position, I usually leave my flaps down in the hangar to keep it

retracted in fluid and not corroding. Note that this is the also the case

with the gear down: shafts are internal and clean.



Robert Forest, N295P.



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Flaps

Submitted by Anonymous on

From: Judy <jandb [at] xtalwind.net>
Subject: Flaps
Date: Sat, 06 Nov 1999 10:17:18 -0500
To: <lancair.list [at] olsusa.com>
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I was under the impression that the 320 model no longer used the

reflexed flaps and was not planning on having a reflex position. I

did read some of the thread about wing twisting and decided it was just

as well not to have reflex in my flaps. Is there an advantage to

reflexing the flaps in the 320 model?

I thought in some of the very old factory News Bulletins that Lance had

announced No noticeable change in air speed with reflex flaps. Did I

miss something else?

Bobby



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Flaps

Submitted by Anonymous on

From: Lynda Frantz <LFrantz [at] compuserve.com>
Sender: Lynda Frantz <LFrantz [at] compuserve.com>
Subject: Flaps
Date: Fri, 12 Nov 1999 21:36:53 -0500
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Message text written by INTERNET:lancair.list [at] olsusa.com

>Why do we use 10 degrees of flap for takeoff (as per  the POH)?<



One reason for using flaps on takeoff is to provide better visibility

during the initial climb to better see pattern traffic.  Not  the answer

you were looking for, I know.



Jim Frantz



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Flaps

Submitted by Anonymous on

From: <Sky2high [at] aol.com>
Subject: Flaps
Date: Sat, 13 Nov 1999 11:29:42 EST
To: <lancair.list [at] olsusa.com>
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My original queries were:



On a Lancair 320/360 with the standard wings and original tail,



a)  What are the lift versus drag relationships at 10 (takeoff), 30 and 45

(full) degrees of flaps?



b)  What is the significant purpose of takeoff flaps?



With respect to b):

My opinion (no data yet) is that in most airplanes (reflexed laminar flow or

not) the flap takeoff position is used to get the airplane off the ground

(highest drag, lowest acceleration) as soon as possible.  I believe that all

flap positions induce drag, but the "takeoff" position provides less drag in

the air than the plane has when rolling on the ground.  One component of the

drag is a result from any added lift.  



At some speed during the airborne part of takeoff, the drag of the flap isn't

worth the benefit, if any.  Of course, one retracts the high drag wheels as

soon as you are unable to land back on the takeoff runway.  I retract the

wheels before the flaps because I believe the wheels are contributing more

drag.  If I was trimmed right for takeoff,  110 Kts is quickly achieved and

raising the flaps produces a nice nose up pitch for the climb out.  I now use

the Deakin technique (AVWEB columnist) of full throttle, 2600 rpm with either

a steep climb attitude at 120 Kts or, more often, the high ground-speed

covering 140 Kts, 500-900 fpm deck angle all the way to cruise altitude. CHTs

are generally no more than 380 degrees regardless of the outside temperature.

 I only take off from towered airports so I don't look out the window....  If

there is any traffic, I step-climb.



So what......  So, is the flap takeoff position only useful in getting off

the ground or controlling deck angle (for visibility) or helping with steep

climb out rates or what?  Is speed better than altitude in a high performance

airplane that, without power, becomes a lawn dart?



With respect to a):

It is my opinion that the flaps deployed beyond "out of reflex" contribute

very little lift and a great deal of drag.  This is, of course, quite useful

in an airplane that is hard to slow down when nearing the airport.  It is

also quite useful in changing the trimmed pitch angle for visibility during

the approach.  It seems that the greatest effect on lift is when you are in

ground effect -- the downward blast of air from full flaps is impressive.



One example of the lift/drag relationship is the CAFE test of Fred's 320,

where it was reported that there was only a few mph (3?) between clean and

dirty stall speeds.  Of course, the angle of attack is quite different.



If the wing was at max performance at speed X when the flaps are "out of

reflex," then should we not do this for the max power-off glide range at

speed X?  What is speed X?  Another words, If the reflexed wing is best at

180-200 knots, what is the best speed for the un-reflexed wing, if any?



So What........  So, what is the best procedure for the go around?  Full

throttle, then wheels up first or flaps up first?  Milk the flaps up and

re-trim or just go to full up?  Should we stop the flaps at "out of reflex"

or continue up?  How about the dramatic pitch force changes?  Are you

prepared for right rudder application?



Any data out there?



Finally, Is the main drag component a product of horizontal stabilizer

negative lift to counteract the flap-induced nose-down pitching moment?



Is everyone snoring by now? Does snoring contribute to drag?



Scott Krueger

N92EX

The EX stands for "experimental".













  

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Flaps

Submitted by Anonymous on

From: Bob Jude <bobjude [at] charter.net>
Sender: Marvin Kaye <marv [at] lancaironline.net>
Subject: Flaps
Date: Mon, 27 Oct 2003 13:32:52 -0500
To: <lml>
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Well, it's been a few years since we last covered this topic, so it's
time
for some LNC2 flap questions again...
Gary, I will make a few comments here but I
will come over and look and discuss it further anytime that's
convenient.
Bob
 
1.  Even after searching the LML archives, I'm unclear as to whether
the
fuselage faired position for the flaps is the zero-degree position, or
the
reflex position  The blueprints indicate that the fuselage-faired
position
is the -7 degrees reflex position, but the manual seems to indicate
that the
reflex position is with the flap trailing edges above the fuselage
fillet.
Which is correct?
I discussed this subject with Lance N, back
about 1992.  He said that the 320 gets no speed benefit from reflexing the
flaps up further than the faired in position.  Some of the words in the
manual apply to the 235 and not 320/360 airframe.  The manual was never
brought up to date for the 320.
 
2.  My fillets are uneven (they differ by 1/2").  I plan on
splitting the
difference on the flap trailing edges(one side 1/4" below
fuselage faired,
the other 1/4" above).  Anybody see any problems with
this method?
I don't quit understand what you mean by "my
fillets are uneven".  Maybe you could consider adding some filler,
structural extension or other add-on to even them out.  Appearance isn't
everything but a nice looking airplane sure helps in re-sale
value.
 
3.  I run out of skin on the flap leading edge when my flaps drop more
than
38 degrees below the faired in position.  For the others who ran
into this
situation, did you add some BID to either the leading or trailing
edge of
the upper flap skin, or did you just install the braces along the
flap
leading edge and get on with business?
I wouldn't worry about any open gaps when the
flaps are down.  Flaps down configuration is supposed to be dirty (high
drag).
 
Thanks for any insight anyone can provide here,
 
Gary Fitzgerald
LNC2 standard build ~60%
Engine: TBD
St. Charles,
MO

Flaps

Submitted by Anonymous on

From: William A. Hogarty <billhogarty [at] gmail.com>
Sender: <marv [at] lancaironline.net>
Subject: Flaps
Date: Thu, 20 Aug 2015 09:12:28 -0400
To: <lml [at] lancaironline.net>
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Jeff:

Just noticed your post on flap problem.

First question, does raising the gear seem normal?  I have some spare screens (somewhere) for the hydraulic
tank, but I have never heard of anyone having a clogged tank before. 

To isolate problem, disconnect the hydraulic cylinder that actuates flaps  (under back seat.)  If the flaps move freely. the problem is not with the linkage binding. Then check that the hose to the hydraulic cylinder is not crimped or leaking. 

 If O.K. this far, I would check the tubing running from the front of the gear housing to the control valve under the inst panel.  Make sure the lines are not kinked.  Blow them out with compressed air.

If O.K, the only culprit left must be the control valve.  Do you have a hydraulic pressure valve showing system pressure?.  This could be a help.  Since the hydraulic pump has to cycle several time to get your flaps down, the pressure must be going somewhere, 

If I remember correctly, starting at 1000+psi, I can lower the flaps without my pump cycling.  Since my memory is not what it was, I will check this out and get back to you.

Good Luck   Bill H. 

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