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Flight Test Update - N776PM

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psm(at)att.net
Guest

Posted: Tue Sep 20, 2011 11:53 am Post subject: Flight Test Update - N776PM

It's been a little over two months since my Zodiac XL got its 

airworthiness certificate.  Yesterday I had my first flight with no 

squawks.  I figured it is time to spread the word on the things I 

found.  Current flight time is around 17 hours.  My typical test flight 

was just over one half hour with just one landing.  This might have been 

a bit shorter if I didn't have to get out from under a class C terminal 

area before climbing to a reasonable test altitude.



Yesterday the air was reasonably cool - around 60 on the ground so it 

must have been around 45 at 5000 MSL where I did my testing.  At full 

throttle the engine ran smoothly and the plane indicated around 120 

knots.  I have not calibrated the airspeed yet, but casual comparison 

with GPS ground speed suggests it is pretty close to correct.  I have a 

Jabiru 3300A with wood Sensenich 64ZK49 propeller (standard stuff when 

you buy the FWF package from Pete at USA Jabiru).  Cylinder head 

temperatures were all green with the highest around 320.  Oil 

temperature was around 170.  At WOT engine RPM was just over 3000 RPM at 

5000 MSL.  CHTs in full throttle climb were around 1100 and in high 

cruise around 1300.



I am sure I can't remember all the problems I fixed in the first two 

months of phase I flight test, but I'll try to recount as many as I can.



1.  Engine cooling was a big problem.  My first attempt at adding rubber 

seals at the front of the cooing ducts was not correct.  I should have 

fitted the rubber seals carefully to the inlets in the cowl.  I also 

needed to adjust the air dams in the right duct (cylinders 1,3,5) but 

the other one never needed any adjustment.



2.  Nose gear bearings were too tight.  The plastic bearings at both the 

top and bottom of the nose gear column restricted movement instead of 

just guiding it.  The nose should move up and down easily when you put 

your weight on the propeller drive shaft.  The plastic bearings as 

delivered from ZAC were much too tight.  I loosened them on original 

installation but that wasn't enough.



3.  Rudder does not return to center when you remove pressure from the 

pedals.  This problem is unresolved.  It doesn't present too much of a 

problem but it is difficult to keep the ball centered unless you give 

the left rudder pedal a good kick after maneuvering.  A related 

unresolved problem is the nose tends to wander in yaw - especially in 

turbulence.  I am thinking nice thoughts of adding some sort of fixed 

vertical stabilizer fin - probably on the bottom of the fuselage to 

correct this.  It is not a big problem but makes flying a bit uncomfortable.



4.  I had a few electronic problems with my Dynon and Garmin avionics.  

The Dynon tachometer needed to have a resistor installed in line with 

the connection to the alternator (through a fuse).  Before adding the 

resistor the tachometer went nuts in mid range power settings but worked 

fine above 2200 RPM and below 1700.



The only problem with the Garmin stuff was I needed to attach a pin to 

ground to enable the built-in intercom on my SL-30.  I also had issues 

setting the squelch, but that was just an operator issue.



5.  Several times I had the quick drains in the fuel tanks turn into 

slow leaks.  This was caused by tiny pieces of aluminum getting caught 

in the tiny O-ring that seals the quick drain.  I got an extra quick 

drain valve and learned how to replace a faulty one with a pail under 

the stream of fuel to collect that fuel that escapes between the time I 

remove one and install the other one.  Then it is a relatively simple 

task to clean out the defective seal and put it aside for the next 

occurrence of this problem.



6.  At one point I discovered the carburetor was barely attached to the 

engine.  It was held in place by the air intake hose but this was still 

a bit scary.  It was easy to loosen both hose clamps that hold the 

carburetor and push it firmly in place before tightening the clamps again.



7.  Another carburetor problem -- the small hose connecting the 

carburetor to the air box came off.  This caused the engine to drop out 

randomly with RPM dropping about 500 revs in turbulence when I reduced 

power for descent.  The engine ran more smoothly when I added power to 

cruise levels.  The original hose had a 3/16 ID and was quite loose on 

the carburetor nipple.  I got some vinyl hose with .170 ID at the 

hardware store and it holds on and works just fine.



8.  Elevator trim was not powerful enough to trim pitch when any flaps 

were employed.  I added an extra fixed tab to the rear of the original 

one and found improvement but I was still unable to get neutral trim 

with full flaps.  A bigger tab fixed this.  I think the final extra tab 

was around 20 square inches to neutralize 20 degrees of flaps.



9.  I had a lot of trouble getting the rudder into a neutral position in 

flight.  The nose gear centers when there is no weight on the gear and 

the connections through the pedals and rudder cables pulls the rudder 

one way or the other until you get this properly adjusted.  This took me 

many small changes.  At one point I didn't like the number of exposed 

threads in one of the turnbuckles and learned you can get forks that are 

about a  half inch longer than the normal ones to give you more 

adjustment room.  I only needed one of these extra length forks to allow 

more "Left" rudder in the cable setup.  (I am getting really good at 

installing safety wire in turnbuckles.)



In all my experience at being a test pilot for an amateur (me) built 

aircraft has been quite an experience.  The only time I felt at all 

scared was when the engine was cutting out.  Mostly it has been a matter 

of getting all the little adjustments made to make the plane fly 

properly.  Now, I am looking forward to spending some time in the 

pattern learning how to do really nice approaches and landings.



Paul

Camas, WA

mtherr(at)yahoo.com
Guest

Posted: Tue Sep 20, 2011 6:17 pm Post subject: Flight Test Update - N776PM

Thanks for sharing Paul.  Now you should start to really enjoy your toy.   



Do not archive



Sent from my iPad



On Sep 20, 2011, at 15:50, Paul Mulwitz <psm(at)att.net> wrote:



 	  Quote: 	
		   

 

 It's been a little over two months since my Zodiac XL got its airworthiness certificate.  Yesterday I had my first flight with no squawks.  I figured it is time to spread the word on the things I found.  Current flight time is around 17 hours.  My typical test flight was just over one half hour with just one landing.  This might have been a bit shorter if I didn't have to get out from under a class C terminal area before climbing to a reasonable test altitude.

 

 Yesterday the air was reasonably cool - around 60 on the ground so it must have been around 45 at 5000 MSL where I did my testing.  At full throttle the engine ran smoothly and the plane indicated around 120 knots.  I have not calibrated the airspeed yet, but casual comparison with GPS ground speed suggests it is pretty close to correct.  I have a Jabiru 3300A with wood Sensenich 64ZK49 propeller (standard stuff when you buy the FWF package from Pete at USA Jabiru).  Cylinder head temperatures were all green with the highest around 320.  Oil temperature was around 170.  At WOT engine RPM was just over 3000 RPM at 5000 MSL.  CHTs in full throttle climb were around 1100 and in high cruise around 1300.

 

 I am sure I can't remember all the problems I fixed in the first two months of phase I flight test, but I'll try to recount as many as I can.

 

 1.  Engine cooling was a big problem.  My first attempt at adding rubber seals at the front of the cooing ducts was not correct.  I should have fitted the rubber seals carefully to the inlets in the cowl.  I also needed to adjust the air dams in the right duct (cylinders 1,3,5) but the other one never needed any adjustment.

 

 2.  Nose gear bearings were too tight.  The plastic bearings at both the top and bottom of the nose gear column restricted movement instead of just guiding it.  The nose should move up and down easily when you put your weight on the propeller drive shaft.  The plastic bearings as delivered from ZAC were much too tight.  I loosened them on original installation but that wasn't enough.

 

 3.  Rudder does not return to center when you remove pressure from the pedals.  This problem is unresolved.  It doesn't present too much of a problem but it is difficult to keep the ball centered unless you give the left rudder pedal a good kick after maneuvering.  A related unresolved problem is the nose tends to wander in yaw - especially in turbulence.  I am thinking nice thoughts of adding some sort of fixed vertical stabilizer fin - probably on the bottom of the fuselage to correct this.  It is not a big problem but makes flying a bit uncomfortable.

 

 4.  I had a few electronic problems with my Dynon and Garmin avionics.  The Dynon tachometer needed to have a resistor installed in line with the connection to the alternator (through a fuse).  Before adding the resistor the tachometer went nuts in mid range power settings but worked fine above 2200 RPM and below 1700.

 

 The only problem with the Garmin stuff was I needed to attach a pin to ground to enable the built-in intercom on my SL-30.  I also had issues setting the squelch, but that was just an operator issue.

 

 5.  Several times I had the quick drains in the fuel tanks turn into slow leaks.  This was caused by tiny pieces of aluminum getting caught in the tiny O-ring that seals the quick drain.  I got an extra quick drain valve and learned how to replace a faulty one with a pail under the stream of fuel to collect that fuel that escapes between the time I remove one and install the other one.  Then it is a relatively simple task to clean out the defective seal and put it aside for the next occurrence of this problem.

 

 6.  At one point I discovered the carburetor was barely attached to the engine.  It was held in place by the air intake hose but this was still a bit scary.  It was easy to loosen both hose clamps that hold the carburetor and push it firmly in place before tightening the clamps again.

 

 7.  Another carburetor problem -- the small hose connecting the carburetor to the air box came off.  This caused the engine to drop out randomly with RPM dropping about 500 revs in turbulence when I reduced power for descent.  The engine ran more smoothly when I added power to cruise levels.  The original hose had a 3/16 ID and was quite loose on the carburetor nipple.  I got some vinyl hose with .170 ID at the hardware store and it holds on and works just fine.

 

 8.  Elevator trim was not powerful enough to trim pitch when any flaps were employed.  I added an extra fixed tab to the rear of the original one and found improvement but I was still unable to get neutral trim with full flaps.  A bigger tab fixed this.  I think the final extra tab was around 20 square inches to neutralize 20 degrees of flaps.

 

 9.  I had a lot of trouble getting the rudder into a neutral position in flight.  The nose gear centers when there is no weight on the gear and the connections through the pedals and rudder cables pulls the rudder one way or the other until you get this properly adjusted.  This took me many small changes.  At one point I didn't like the number of exposed threads in one of the turnbuckles and learned you can get forks that are about a  half inch longer than the normal ones to give you more adjustment room.  I only needed one of these extra length forks to allow more "Left" rudder in the cable setup.  (I am getting really good at installing safety wire in turnbuckles.)

 

 In all my experience at being a test pilot for an amateur (me) built aircraft has been quite an experience.  The only time I felt at all scared was when the engine was cutting out.  Mostly it has been a matter of getting all the little adjustments made to make the plane fly properly.  Now, I am looking forward to spending some time in the pattern learning how to do really nice approaches and landings.

 

 Paul

 Camas, WA

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Wed Sep 21, 2011 2:13 am Post subject: Flight Test Update - N776PM

Did you set the rudder cable tension with no weight on the nose-wheel? The rudder cable tension will decrease with any deflection of the strut due to weight on the wheel because of the angle of the strut. Too much tension will make it harder to self center in flight.



On Sep 20, 2011, at 3:50 PM, Paul Mulwitz wrote:



 	  Quote: 	
		   3.  Rudder does not return to center when you remove pressure from the pedals.  This problem is unresolved.  It doesn't present too much of a problem but it is difficult to keep the ball centered unless you give the left rudder pedal a good kick after maneuvering.  


	




-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

psm(at)att.net
Guest

Posted: Wed Sep 21, 2011 2:37 am Post subject: Flight Test Update - N776PM

Hi Brian,



The nose strut is fully extended when the plane is sitting normally.  

This should center the nose wheel, but in my plane it doesn't do that.  

I don't know exactly why.  Also, in flight the nose wheel doesn't center 

very well.   It does rest on the "V" shape in the lower bearing block, 

but the rotation of the column seems somewhat random.  If I kick the 

left pedal it moves left and stays there.  Similarly, if I kick the 

right pedal it stays rotated a bit to the right.



I spoke with an engineer from ZAC about this when I was at OSH.  He 

suggested reducing the "V" shape and making it more flat.  This is 

supposed to make it easier to rotate the nose gear while loaded by the 

huge bungee.



I don't think there is any relationship between the strut position and 

rudder cable tension.  Rudder cable tension works against the position 

of the rudder pedals.  The rudder pedals don't move when the strut goes 

up and down.



I have been careful to set all the cable tensions according to the 

latest requirements from ZAC.  This is problematical since some of the 

required information is not specified.  The elevator position is 

critical to the elevator cable tensions but there is no discussion of 

this position in any of the documents I have seen.  Fortunately, it 

doesn't seem to make much difference what elevator cable tension is used.



Paul



On 9/21/2011 3:10 AM, Bryan Martin wrote:

 	  Quote: 	
		   



 Did you set the rudder cable tension with no weight on the nose-wheel? The rudder cable tension will decrease with any deflection of the strut due to weight on the wheel because of the angle of the strut. Too much tension will make it harder to self center in flight.



 On Sep 20, 2011, at 3:50 PM, Paul Mulwitz wrote:



> 3.  Rudder does not return to center when you remove pressure from the pedals.  This problem is unresolved.  It doesn't present too much of a problem but it is difficult to keep the ball centered unless you give the left rudder pedal a good kick after maneuvering.

jaybannist(at)cs.com
Guest

Posted: Wed Sep 21, 2011 4:28 am Post subject: Flight Test Update - N776PM

Paul is wrong about the relationship of the nose gear strut position to the rudder pedals.  The nose gear strut position definitely does effect the rudder pedals.  If it moves up, both pedals move rearward, loosening the rudder cables. The attached pdf shows the geometry.

 

 However, it did not effect my setting of the rudder cable tension since the bungee kept the nose gear strut on the stop without lifting the nose.

 

 Jay  

   

  

     

  

    

     

  

     

  

    --

pedal-nose_strut.pdf

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Download

Filename:

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psm(at)att.net
Guest

Posted: Wed Sep 21, 2011 6:13 am Post subject: Flight Test Update - N776PM

Hi Jay,

     

     Looking at your drawing, I would guess the amount of rudder pedal     movement caused by nose gear strut movement is a function of the     setting of the angle of the rudder pedals.  Put differently, if the     pedals are moved toward the rear (for short legged guys like me)     then the correlated movement would be minimal.  If the pedals are     set forward (for tall guys) then the movement would be more     pronounced.

     

     In any case, I agree with Bob that it is not a great idea to make     things different by reducing the rudder cable tension.  I think my     approach of adjusting the relative rudder cable lengths is a better     way to get neutral rudder trim.

     

     Paul

     

     P.S.  I had a typo in my tail number.  It is N773PM.

     

     On 9/21/2011 5:25 AM, Jay Bannister wrote:     [quote]Paul             is wrong about the relationship of the nose gear strut             position to the rudder pedals.  The nose gear strut position definitely does effect             the rudder pedals.  If it             moves up, both pedals move rearward, loosening the rudder             cables. The             attached pdf shows the geometry.

         

             However, it did not effect my setting of the rudder cable             tension since the bungee kept the nose gear strut on the             stop without lifting the nose.

             

             Jay  [b]

jaybannist(at)cs.com
Guest

Posted: Wed Sep 21, 2011 6:48 am Post subject: Flight Test Update - N776PM

Not so.  The geometry remains the same.   

  

     

  

    

     

  

     

  

    --

psm(at)att.net
Guest

Posted: Wed Sep 21, 2011 7:08 am Post subject: Flight Test Update - N776PM

Jay, 

     

     I don't want to make a big argument over this, but I'm afraid you     are not seeing the truth.

     

     The angle between the rudder pedals and the nose gear strut will     influence how movement in the strut will cause movement in the     pedals.  Technically this is not geometry but is trigonometry.      Perhaps  you are not considering that a change in angle between the     pedals and strut requires a change in length of the tie rods.

     

     If the pedals and strut are parallel then a small movement in the     strut will not cause a noticeable movement in the pedals.  As the     angle increases the connected movement increases.  I'm sure there is     a SIN or COS function here somewhere but I don't have the energy to     work out the equations.

     

     In the real world, the strut doesn't move very far at all because     the bungee is very strong.  I have tried to move it on the ground     and my weight is only enough to get the strut to move an inch or     so.  It needs to be free to move, but I doubt you will ever see much     more than an inch or two in the strut which might translate to a few     millimeters movement in the rudder pedals.

     

     Respectfully,

     

     Paul

     

     On 9/21/2011 7:44 AM, Jay Bannister wrote:     [quote]Not so.  The geometry remains the same.                       

           

            

           

            

           

            

           

           -----Original             Message-----

             From: Paul Mulwitz <psm(at)att.net> (psm(at)att.net)

             To: zenith601-list <zenith601-list(at)matronics.com> (zenith601-list(at)matronics.com)

             Sent: Wed, Sep 21, 2011 9:15 am

             Subject: Re: Flight Test Update - N776PM

             

                            Hi Jay,

               

               Looking at your drawing, I would guess the amount of               rudder pedal movement caused by nose gear strut movement               is a function of the setting of the angle of the rudder               pedals.  Put differently, if the pedals are moved toward               the rear (for short legged guys like me) then the               correlated movement would be minimal.  If the pedals are               set forward (for tall guys) then the movement would be               more pronounced.

               

               In any case, I agree with Bob that it is not a great idea               to make things different by reducing the rudder cable               tension.  I think my approach of adjusting the relative               rudder cable lengths is a better way to get neutral rudder               trim.

               

               Paul                              

                        

                 	  Quote: 	
		  

	
     [b]

jaybannist(at)cs.com
Guest

Posted: Wed Sep 21, 2011 7:26 am Post subject: Flight Test Update - N776PM

Paul, 

 

 Respectfully -  you are dead wrong.  My graphic triggernometry is accurate and what I am telling you is factual.

 

 And you won't make a big argument over this because this is my last post on the subject. 

 

 Jay   

  

     

  

    

     

  

     

  

    --

JohnDRead(at)aol.com
Guest

Posted: Wed Sep 21, 2011 3:15 pm Post subject: Flight Test Update - N776PM

Jay,

         You had better go and  recheck your trigonometry. Adjusting the pedals to the rear making the  axis of the rudder pedal parallel to the nose strut will fix the cable  tension problem. This problem is similar the need to have the axis of the  elevator bellcrank parrallel to the pivot points on the elevator. do not  archive.

  

 Regards,  John



CH701 - Colorado - Jabiru 3300



Cell: 719-494-4567

Home:  303-648-3261   

  



 [quote][b]

jaybannist(at)cs.com
Guest

Posted: Wed Sep 21, 2011 4:17 pm Post subject: Flight Test Update - N776PM

crickets

 

 do not archive

    

  

     

  

    

     

  

     

  

    --

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Wed Sep 21, 2011 6:43 pm Post subject: Flight Test Update - N776PM

The nose strut slides up and down parallel to the firewall, the rudder pedals are fixed to pivot at the bottom to the cabin floor and higher up to the steering rods connected to the nose strut. This configuration makes it impossible for the pedals to remain parallel to the strut as the strut deflects. This means that the rudder cable tension will vary with strut deflection. If the distance between the connection points of the cable at the pedal and at the rudder horn varies by a small amount, it will have a significant effect on the cable tension. 

The cable tension on the ground is not important, the in-flight tension is very important. So, the tension should be set for the in-flight configuration, i.e. with zero strut deflection. Even an sixteenth of an inch of deflection can have a significant effect on tension. If the cables are too tight in flight, friction may make it difficult to self center.

On Sep 21, 2011, at 11:04 AM, Paul Mulwitz wrote:

[quote] Jay, 

 I don't want to make a big argument over this, but I'm afraid you are not seeing the truth.

 The angle between the rudder pedals and the nose gear strut will influence how movement in the strut will cause movement in the pedals.  Technically this is not geometry but is trigonometry.  Perhaps  you are not considering that a change in angle between the pedals and strut requires a change in length of the tie rods.

 If the pedals and strut are parallel then a small movement in the strut will not cause a noticeable movement in the pedals.  As the angle increases the connected movement increases.  I'm sure there is a SIN or COS function here somewhere but I don't have the energy to work out the equations.

 In the real world, the strut doesn't move very far at all because the bungee is very strong.  I have tried to move it on the ground and my weight is only enough to get the strut to move an inch or so.  It needs to be free to move, but I doubt you will ever see much more than an inch or two in the strut which might translate to a few millimeters movement in the rudder pedals.

 Respectfully,

 Paul

 On 9/21/2011 7:44 AM, Jay Bannister wrote:

> Not so.  The geometry remains the same.

> 

> 

> 

> 

> --

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

psm(at)att.net
Guest

Posted: Wed Sep 21, 2011 7:00 pm Post subject: Flight Test Update - N776PM

Hi Bryan,

I agree with your comment in principle, but the actual amount of 

movement in the rudder pedals will vary depending on the configuration.

The Zodiac has fixed seat location, so the only way to adjust the 

position for people of different length legs is to rotate the rudder 

pedals in their neutral location.  If you rotate them back far enough 

the upright portion of the rudder pedal can be parallel to the nose gear 

strut.  In this case small movements in the strut will make much smaller 

movements in the rudder pedals.  This is because the rods connecting the 

strut to the pedals will be perpendicular to the pedal upright members 

and can move without really moving the pedal much at all.

As you  move the pedals closer to the firewall for taller people the 

angle between the tie rods and the pedal upright member moves away from 

90 degrees.  This means the same movement in the strut will have a 

bigger impact on the rudder pedal location.

As I mentioned earlier, the nose strut movement is pretty small.  I have 

not measured it in normal flight and landing events, but I would guess a 

normal (gentle) touchdown might move the strut less than an inch.  In 

this case and the case of setting the pedals for a short legged pilot I 

doubt you would be able to measure any change at all in either the pedal 

position or cable tension.

I agree with you that the tension in flight is the most important.  This 

is the normal situation anyway since the normal position of the strut 

when the plane is on the ground is fully extended.

Paul

On 9/21/2011 7:40 PM, Bryan Martin wrote:

[quote] 

 The nose strut slides up and down parallel to the firewall, the rudder pedals are fixed to pivot at the bottom to the cabin floor and higher up to the steering rods connected to the nose strut. This configuration makes it impossible for the pedals to remain parallel to the strut as the strut deflects. This means that the rudder cable tension will vary with strut deflection. If the distance between the connection points of the cable at the pedal and at the rudder horn varies by a small amount, it will have a significant effect on the cable tension.

 The cable tension on the ground is not important, the in-flight tension is very important. So, the tension should be set for the in-flight configuration, i.e. with zero strut deflection. Even an sixteenth of an inch of deflection can have a significant effect on tension. If the cables are too tight in flight, friction may make it difficult to self center.

 On Sep 21, 2011, at 11:04 AM, Paul Mulwitz wrote:

> Jay,

>

> I don't want to make a big argument over this, but I'm afraid you are not seeing the truth.

>

> The angle between the rudder pedals and the nose gear strut will influence how movement in the strut will cause movement in the pedals.  Technically this is not geometry but is trigonometry.  Perhaps  you are not considering that a change in angle between the pedals and strut requires a change in length of the tie rods.

>

> If the pedals and strut are parallel then a small movement in the strut will not cause a noticeable movement in the pedals.  As the angle increases the connected movement increases.  I'm sure there is a SIN or COS function here somewhere but I don't have the energy to work out the equations.

>

> In the real world, the strut doesn't move very far at all because the bungee is very strong.  I have tried to move it on the ground and my weight is only enough to get the strut to move an inch or so.  It needs to be free to move, but I doubt you will ever see much more than an inch or two in the strut which might translate to a few millimeters movement in the rudder pedals.

>

> Respectfully,

>

> Paul

>

> On 9/21/2011 7:44 AM, Jay Bannister wrote:

>> Not so.  The geometry remains the same.

>>

>>

>>

>>

>> --

rsteele(at)rjsit.com
Guest

Posted: Wed Sep 21, 2011 7:36 pm Post subject: Flight Test Update - N776PM

Without rehashing the geometry, I will say that the only two 601s I've  

seen with the cowl off did NOT have the strut fully extended on the  

ground.  One hasn't yet flown (mine) but the other has with no  

complaints that I'm aware of.  Might this be a clue to your problem?   

I'm curious about the at rest positions other may have seen.



Keep up the reports.  Very interesting.



Ron

DO NOT ARCHIVE



On Sep 21, 2011, at 10:58 PM, Paul Mulwitz wrote:



 	  Quote: 	
		  

 I agree with you that the tension in flight is the most important.   

 This is the normal situation anyway since the normal position of the  

 strut when the plane is on the ground is fully extended.



 Paul

psm(at)att.net
Guest

Posted: Wed Sep 21, 2011 8:07 pm Post subject: Flight Test Update - N776PM

Hi Ron,

How far depressed was the strut in the cases you saw?  What engine did 

these planes have?

Keep in mind the Jabiru engine I have installed is much lighter than a 

Continental, Lycoming, Corvair, or Subaru.  The only engine that has a 

similar weight is the Rotax 912.  I believe there is a 100 pound 

difference (give or take) in the installed weight of the Rotax and 

Jabiru compared to the other engines.   I'm sure the engine weight can 

have an impact on the resting position of the nose strut.

Paul

On 9/21/2011 8:34 PM, Ronald Steele wrote:

 	  Quote: 	

 Without rehashing the geometry, I will say that the only two 601s I've 

 seen with the cowl off did NOT have the strut fully extended on the 

 ground.  One hasn't yet flown (mine) but the other has with no 

 complaints that I'm aware of.  Might this be a clue to your problem?  

 I'm curious about the at rest positions other may have seen.

 Keep up the reports.  Very interesting.

 Ron

 DO NOT ARCHIVE

 On Sep 21, 2011, at 10:58 PM, Paul Mulwitz wrote:

>

> I agree with you that the tension in flight is the most important.  

> This is the normal situation anyway since the normal position of the 

> strut when the plane is on the ground is fully extended.

>

> Paul

>

daveaustin2(at)primus.ca
Guest

Posted: Thu Sep 22, 2011 10:35 am Post subject: Flight Test Update - N776PM

---

psm(at)att.net
Guest

Posted: Thu Sep 22, 2011 11:01 am Post subject: Flight Test Update - N776PM

Hi Dave,

I don't know for sure, but I think that would not be a problem.  The 

trim tab size increase is something less than 50 percent.  Also, the 

elevator authority is a lot higher than the total trim force.

I have taken off without adjusting the trim from full flaps to neutral 

with no flaps and the amount of force needed to get the desired pitch 

was easy to generate.  This might be a direct answer to your question.

Paul

Camas, WA

On 9/22/2011 11:32 AM, Dave Austin wrote:

 	  Quote: 	

> Hi Paul,

> Interesting comments.  One question:  With your enlarged trim tab, if 

> you had an elevator trim tab runaway (I have!) can you overcome it 

> with the stick?   Try it at a high altitude before you do get a runaway!

> Dave Austin  HDS 912U

>

rsteele(at)rjsit.com
Guest

Posted: Thu Sep 22, 2011 2:20 pm Post subject: Flight Test Update - N776PM

Not depressed much, may 1/8".  The point is that if you have no  

depression, you my have a bungee that is too strong and you may be  

getting some friction at the top of the strut that interferes with the  

self centering.



Ron



On Sep 22, 2011, at 12:04 AM, Paul Mulwitz wrote:



 	  Quote: 	
		   



 Hi Ron,



 How far depressed was the strut in the cases you saw?  What engine  

 did these planes have?



 Keep in mind the Jabiru engine I have installed is much lighter than  

 a Continental, Lycoming, Corvair, or Subaru.  The only engine that  

 has a similar weight is the Rotax 912.  I believe there is a 100  

 pound difference (give or take) in the installed weight of the Rotax  

 and Jabiru compared to the other engines.   I'm sure the engine  

 weight can have an impact on the resting position of the nose strut.



 Paul



 On 9/21/2011 8:34 PM, Ronald Steele wrote:

> 

> >

>

> Without rehashing the geometry, I will say that the only two 601s  

> I've seen with the cowl off did NOT have the strut fully extended  

> on the ground.  One hasn't yet flown (mine) but the other has with  

> no complaints that I'm aware of.  Might this be a clue to your  

> problem?  I'm curious about the at rest positions other may have  

> seen.

>

> Keep up the reports.  Very interesting.

>

> Ron

> DO NOT ARCHIVE

>

> On Sep 21, 2011, at 10:58 PM, Paul Mulwitz wrote:

>

>>

>> I agree with you that the tension in flight is the most  

>> important.  This is the normal situation anyway since the normal  

>> position of the strut when the plane is on the ground is fully  

>> extended.

>>

>> Paul

>>

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