Original Posted By: N321TX(at)wmconnect.com
Can you guys estimate the max amount of force put on the rudder bar?Mine is made of Ash wood which is very strong, I'm just a little concerned thatthere's not enough "meat" left around the cable bolts for my taste.Any ideas?Douwe________________________________________________________________________________
Pietenpol-List: rudder bar pressures
Re: Pietenpol-List: rudder bar pressures
Original Posted By: Douwe Blumberg
Figure in a panic your legs could put MANY hundreds (probably in the low thousands)of pounds each on the rudder bar. It is common after an accident to seethe steel brake peddle rod bent to the floor in cars (and the bend didn't happenfrom impact). Adrenaline and pure terror can make your body incredibly strong.That said, if you are jamming down THAT hard on the rudder bar you are ina LOT more trouble than failing the bar will cause. This is where a little"logic engineering" comes in. Figure what load the pivot bolt can take (bendingor sheer, whichever is less) and test load your rudder bar with that many pounds.That will give you a fair assurance that the pivot bolt will fail beforethe bar and that is all you need. If there is a flaw in the wood or you carvedthe cross section too much it will show up in your test.All problems don't require complex analysis to find out what is "good enough" andI haven't heard of a pivot bolt failing in a Pietenpol yet.Hank J ----- Original Message -----
Figure in a panic your legs could put MANY hundreds (probably in the low thousands)of pounds each on the rudder bar. It is common after an accident to seethe steel brake peddle rod bent to the floor in cars (and the bend didn't happenfrom impact). Adrenaline and pure terror can make your body incredibly strong.That said, if you are jamming down THAT hard on the rudder bar you are ina LOT more trouble than failing the bar will cause. This is where a little"logic engineering" comes in. Figure what load the pivot bolt can take (bendingor sheer, whichever is less) and test load your rudder bar with that many pounds.That will give you a fair assurance that the pivot bolt will fail beforethe bar and that is all you need. If there is a flaw in the wood or you carvedthe cross section too much it will show up in your test.All problems don't require complex analysis to find out what is "good enough" andI haven't heard of a pivot bolt failing in a Pietenpol yet.Hank J ----- Original Message -----
Re: Pietenpol-List: rudder bar pressures
Original Posted By: Douwe Blumberg
Douwe,From what I remember, the rudder bar hits the bottom of the front seat as a stop.So as long as that happens before the rudder itself hits any kind of stop,there will be no real force on the cables and hardware. Since your feet areto the outside of the "tube", under normal operation, there should be littleor no forces on the pivot bolt. Now if you're thinking of a "panic stop" whereboth feet go forward, guess it would be the strength of the wood or the pivotbolt.walt evansNX140DL ----- Original Message -----
Douwe,From what I remember, the rudder bar hits the bottom of the front seat as a stop.So as long as that happens before the rudder itself hits any kind of stop,there will be no real force on the cables and hardware. Since your feet areto the outside of the "tube", under normal operation, there should be littleor no forces on the pivot bolt. Now if you're thinking of a "panic stop" whereboth feet go forward, guess it would be the strength of the wood or the pivotbolt.walt evansNX140DL ----- Original Message -----
Re: Pietenpol-List: rudder bar pressures
Original Posted By: walt evans
You are right that the loads on the cables, rudder horns and other parts aft ofthe bar are not affected by the pressure on the bar. That is the primary advantageof using a bar in place of rudder pedals, it allows all parts aft of thebar to use design loads based on air loads instead of pilot induced loads. Several designs had serious damage to the tails because builders substituted pedalswhere bars were called for and pressure on both pedals at once damaged therudder horns, rudder hinges and in one case the aluminum longerons in an ultralight.Most people don't even realize they are pressing on both pedals atonce until pressure reaches slightly OVER their standing weight! That is whyI said using the pivot bolt strength as a limit would work as a poor mans methodof determining the strength requirement for the bar. I think you would besurprised at the force we keep on the rudder controls all the time that resolvesitself as either load on the bar pivot or tension in the cables and other partswith pedals. How many times have you stretched in the cockpit and pushedyourself back and up in the seat by pushing on both sides of the bar?Hank ----- Original Message -----
You are right that the loads on the cables, rudder horns and other parts aft ofthe bar are not affected by the pressure on the bar. That is the primary advantageof using a bar in place of rudder pedals, it allows all parts aft of thebar to use design loads based on air loads instead of pilot induced loads. Several designs had serious damage to the tails because builders substituted pedalswhere bars were called for and pressure on both pedals at once damaged therudder horns, rudder hinges and in one case the aluminum longerons in an ultralight.Most people don't even realize they are pressing on both pedals atonce until pressure reaches slightly OVER their standing weight! That is whyI said using the pivot bolt strength as a limit would work as a poor mans methodof determining the strength requirement for the bar. I think you would besurprised at the force we keep on the rudder controls all the time that resolvesitself as either load on the bar pivot or tension in the cables and other partswith pedals. How many times have you stretched in the cockpit and pushedyourself back and up in the seat by pushing on both sides of the bar?Hank ----- Original Message -----
Re: Pietenpol-List: rudder bar pressures
Original Posted By: "Peter W Johnson"
Subject: Re: Pietenpol-List: rudder bar pressuresIn a message dated 9/6/04 10:36:17 AM Central Daylight Time, douweblumberg(at)earthlink.net writes:>Douwe,Ash wood is the Wrong material for a rudder bar. Remove it, and build one the way the plans show. The rudder bar is one of the few things the plans callout specifically 'Rudder bar is chrome molly tube' (4130 steel).Chuck G.________________________________________________________________________________
Subject: Re: Pietenpol-List: rudder bar pressuresIn a message dated 9/6/04 10:36:17 AM Central Daylight Time, douweblumberg(at)earthlink.net writes:>Douwe,Ash wood is the Wrong material for a rudder bar. Remove it, and build one the way the plans show. The rudder bar is one of the few things the plans callout specifically 'Rudder bar is chrome molly tube' (4130 steel).Chuck G.________________________________________________________________________________
RE: Pietenpol-List: strap fitting between landing/flying wire attach points
Original Posted By: owner-pietenpol-list-server(at)matronics.com
Douwe,My British produced plans call for straps front and back. I have theminstalled.CheersPeterWonthaggi Australiahttp://www.cpc-world.com -----Original Message-----
Douwe,My British produced plans call for straps front and back. I have theminstalled.CheersPeterWonthaggi Australiahttp://www.cpc-world.com -----Original Message-----
Re: Pietenpol-List: rudder bar pressures
Original Posted By:
There is nothing wrong (engineering wise, I'm not going to the "originality"place again) with a wood rudder bar. I find the feel better than tubesthrough soft sole shoes. The max force is limited by the shear or bendingstrength (which ever is lower) of the pivot pin that attaches the bar(unless the hard point the pivot goes through in the fuselage is weaker).Remember, when you are being chased by a lion, you don't need to be fasterthan the lion. You only need to be faster than the guy next to you. Justmake sure the bar is stronger than the weakest part that the bar load passesthrough. Once you know the strength of the pivot pin, just hang the barfrom a piece of rod stock or a bolt of the same material in double shear(only half the load is in the pin that way) and hang half the pivot strengthload from each end of the bar. If it doesn't fail, it's OK.Hank J----- Original Message -----
There is nothing wrong (engineering wise, I'm not going to the "originality"place again) with a wood rudder bar. I find the feel better than tubesthrough soft sole shoes. The max force is limited by the shear or bendingstrength (which ever is lower) of the pivot pin that attaches the bar(unless the hard point the pivot goes through in the fuselage is weaker).Remember, when you are being chased by a lion, you don't need to be fasterthan the lion. You only need to be faster than the guy next to you. Justmake sure the bar is stronger than the weakest part that the bar load passesthrough. Once you know the strength of the pivot pin, just hang the barfrom a piece of rod stock or a bolt of the same material in double shear(only half the load is in the pin that way) and hang half the pivot strengthload from each end of the bar. If it doesn't fail, it's OK.Hank J----- Original Message -----
Re: Pietenpol-List: rudder bar pressures
Original Posted By: "hjarrett"
IMO flight controls should be made from 4130 steel (and in some carefullyengineered cases, aluminum).Would you use a broom handle for a control stick?!DJ:)----- Original Message -----
IMO flight controls should be made from 4130 steel (and in some carefullyengineered cases, aluminum).Would you use a broom handle for a control stick?!DJ:)----- Original Message -----
> Re: Pietenpol-List: rudder bar pressures
Original Posted By: Mike Luther
> Re: Pietenpol-List: rudder bar pressures
Original Posted By: Mike Luther
RE: Pietenpol-List: rudder bar pressures
Original Posted By: owner-pietenpol-list-server(at)matronics.com
Actually, the old WACO biplanes did use wood for their control sticks. Ibelieve they were hickory but am not sure. There is at least one advantageto a wooden control stick - it does not affect the compass. The compass onmy Piet is in the instrument panel and the steel stick comes close enough tothe compass that it definitely affects the compass. Rapid stick movementscan make the compass swing through an entire revolution. Not that I will bemakeing rapid movements while trying to fly a compass course, but it doesmean that when swinging the compass, the stick must be held in level flightposition or the compass will give erroneous readings.Jack -----Original Message-----
Actually, the old WACO biplanes did use wood for their control sticks. Ibelieve they were hickory but am not sure. There is at least one advantageto a wooden control stick - it does not affect the compass. The compass onmy Piet is in the instrument panel and the steel stick comes close enough tothe compass that it definitely affects the compass. Rapid stick movementscan make the compass swing through an entire revolution. Not that I will bemakeing rapid movements while trying to fly a compass course, but it doesmean that when swinging the compass, the stick must be held in level flightposition or the compass will give erroneous readings.Jack -----Original Message-----
Re: Pietenpol-List: rudder bar pressures
Original Posted By: "DJ Vegh"
You can make ANYTHING in an airplane from anything you want as long as theproperties of the material you select along with the section characteristicsof the part will carry the loads. I have a garage broom in my house that Iwouldn't hesitate a moment to use for a stick, as long as I tested it andproved it was capable of taking the loads I would impose on it. There isNOTHING magic about "aircraft" materials and an improperly designed Titaniumpart will fail long before a properly designed one made from old toiletpaper tubes. You actually made my point when you said "in some carefully engineered cases". Hundreds of planes fly with wood rudder bars andsticks. Test it for the loads it will see plus a safety margin and go fly.You can't just go around substituting materials, but that isn't what he did.Hank (that broom has one nice piece of wood in the handle) J----- Original Message -----
You can make ANYTHING in an airplane from anything you want as long as theproperties of the material you select along with the section characteristicsof the part will carry the loads. I have a garage broom in my house that Iwouldn't hesitate a moment to use for a stick, as long as I tested it andproved it was capable of taking the loads I would impose on it. There isNOTHING magic about "aircraft" materials and an improperly designed Titaniumpart will fail long before a properly designed one made from old toiletpaper tubes. You actually made my point when you said "in some carefully engineered cases". Hundreds of planes fly with wood rudder bars andsticks. Test it for the loads it will see plus a safety margin and go fly.You can't just go around substituting materials, but that isn't what he did.Hank (that broom has one nice piece of wood in the handle) J----- Original Message -----
Re: Pietenpol-List: rudder bar pressures
Original Posted By: "Jack Phillips"
So do Stearmans----- Original Message -----
So do Stearmans----- Original Message -----
> > Re: Pietenpol-List: rudder bar pressures
Original Posted By: Michael D Cuy
> > Re: Pietenpol-List: rudder bar pressures
Original Posted By: Michael D Cuy
Re: Pietenpol-List: welding
Original Posted By: Jim Ash
Next month's issue of Sport Aviation will have the first in a series of articleson welding aircraft alloy steels. It will be very helpful to those interestedin welding parts for aircraft use ( and others as well). The series is authoredby a gentleman named Scott Helzer. He recently conducted an extensive researchprogram on the methodology of welding for aircraft. I think this willbe very helpful and put to rest a lot of speculation as to what are the bestpractices.Jon Botsford ----- Original Message -----
Next month's issue of Sport Aviation will have the first in a series of articleson welding aircraft alloy steels. It will be very helpful to those interestedin welding parts for aircraft use ( and others as well). The series is authoredby a gentleman named Scott Helzer. He recently conducted an extensive researchprogram on the methodology of welding for aircraft. I think this willbe very helpful and put to rest a lot of speculation as to what are the bestpractices.Jon Botsford ----- Original Message -----
Re: Pietenpol-List: rudder bar pressures
Original Posted By: "Gary Gower"
I like safety margins, I'll use BOTH hands (and have my wife pulling too,just to be safe).Hank J----- Original Message -----
I like safety margins, I'll use BOTH hands (and have my wife pulling too,just to be safe).Hank J----- Original Message -----
> > > Re: Pietenpol-List: rudder bar pressures
Original Posted By: Don Morris
Re: Pietenpol-List: rudder bar pressures
Original Posted By: "hjarrett"
I have a question that deviates slightly from the main topic (sorry)concerning moving the rudder bar to the front cockpit and connecting the rear petals to the front rudder bar using solid tubing as has beendiscussed on this group. This way the front bar takes up the force fromboth rear petals being pressed. Question is what are the negatives tothis arrangement? Must be some problem with it since it seems few people have done it.ThanksRick Holland >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>There is nothing wrong (engineering wise, I'm not going to the >"originality">place again) with a wood rudder bar. I find the feel better than tubes>through soft sole shoes. The max force is limited by the shear or bending>strength (which ever is lower) of the pivot pin that attaches the bar>(unless the hard point the pivot goes through in the fuselage is weaker).>Remember, when you are being chased by a lion, you don't need to be faster>than the lion. You only need to be faster than the guy next to you. Just>make sure the bar is stronger than the weakest part that the bar load >passes>through. Once you know the strength of the pivot pin, just hang the bar>from a piece of rod stock or a bolt of the same material in double shear>(only half the load is in the pin that way) and hang half the pivot >strength>load from each end of the bar. If it doesn't fail, it's OK.>Hank J________________________________________________________________________________
I have a question that deviates slightly from the main topic (sorry)concerning moving the rudder bar to the front cockpit and connecting the rear petals to the front rudder bar using solid tubing as has beendiscussed on this group. This way the front bar takes up the force fromboth rear petals being pressed. Question is what are the negatives tothis arrangement? Must be some problem with it since it seems few people have done it.ThanksRick Holland >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>There is nothing wrong (engineering wise, I'm not going to the >"originality">place again) with a wood rudder bar. I find the feel better than tubes>through soft sole shoes. The max force is limited by the shear or bending>strength (which ever is lower) of the pivot pin that attaches the bar>(unless the hard point the pivot goes through in the fuselage is weaker).>Remember, when you are being chased by a lion, you don't need to be faster>than the lion. You only need to be faster than the guy next to you. Just>make sure the bar is stronger than the weakest part that the bar load >passes>through. Once you know the strength of the pivot pin, just hang the bar>from a piece of rod stock or a bolt of the same material in double shear>(only half the load is in the pin that way) and hang half the pivot >strength>load from each end of the bar. If it doesn't fail, it's OK.>Hank J________________________________________________________________________________
Re: Pietenpol-List: rudder bar pressures
Original Posted By: "Rick Holland"
You lost me there Rick. If you are attaching the front and rear bars withonly one tube NONE of the forces from pressing both sides of the aft bar atonce would be transmitted to the front bar. Same goes for pressing bothsides of the front bar at once. Only the differential pressure would passto the other bar.Hank J----- Original Message -----
You lost me there Rick. If you are attaching the front and rear bars withonly one tube NONE of the forces from pressing both sides of the aft bar atonce would be transmitted to the front bar. Same goes for pressing bothsides of the front bar at once. Only the differential pressure would passto the other bar.Hank J----- Original Message -----
Re: Pietenpol-List: rudder bar pressures
Original Posted By: "Stacy Clark"
Subject: Re: Pietenpol-List: rudder bar pressuresIn a message dated 9/12/04 6:29:14 PM Central Daylight Time, at7000ft(at)hotmail.com writes:>Rick,Problems are quite a few in this set up. If one of the joints fail, you will be applying a LOT of pressure to the rudder horn, leading to failure of rudder control. Another reason is that you can't remove the controls in the front, if you are flying solo, and need the space for baggage. There is no doubtthat Bernard Pietenpol considered this set up, and niched the idea. If toe brakes are your thinking, well I have heel brakes, and they are more than adequate, and easy enough to get used to. There are Many places that you can personalize your homebuilt, but changing the original control set up, includingmaterial, is NOT one of them. Build it to the plans, and it will work just fine.Chuck GantzerNX770CG________________________________________________________________________________
Subject: Re: Pietenpol-List: rudder bar pressuresIn a message dated 9/12/04 6:29:14 PM Central Daylight Time, at7000ft(at)hotmail.com writes:>Rick,Problems are quite a few in this set up. If one of the joints fail, you will be applying a LOT of pressure to the rudder horn, leading to failure of rudder control. Another reason is that you can't remove the controls in the front, if you are flying solo, and need the space for baggage. There is no doubtthat Bernard Pietenpol considered this set up, and niched the idea. If toe brakes are your thinking, well I have heel brakes, and they are more than adequate, and easy enough to get used to. There are Many places that you can personalize your homebuilt, but changing the original control set up, includingmaterial, is NOT one of them. Build it to the plans, and it will work just fine.Chuck GantzerNX770CG________________________________________________________________________________