Brodhead Pietenpol Association

Original Posted By: "hjarrett"
Don't know if you guys feel this way too or not , but my Piet flies so much betterwith a passenger in the turbulent midday . It's a subtle thing, and not justthe extra weight, but the yaw control greatly improves. With just me , itis stomach churning, and the plane seems to pivot around me. With someone inthe front, the plane pivots further forward. And is back to climbing like astandard Cub.Funny, it's something I wouldn't have imagined. Anyone else see this? Or is thisa known in the high time Piet guys?Guess thats one of the drawbacks to building light. At 595# empty, I'm at thelight end of the spectrum. If I had a fatter one maybe wouldn't see this. Also, thanks to all who responded over the winter to my problems with "stall"landings. Put all the advice into play, and found my weakness.walt evansNX140DLLast night was the "Tribute to Harry Chapin" concert in my town,,,,,,Great!________________________________________________________________________________

Original Posted By: walt evans
What you are describing is typical behavior in an aft CG condition. Have you donea weight and balance and checked where on the wing chord the CG falls? Allthe talk on the group about how many inches aft of the firewall the CG shouldbe and moving the wing fore and aft makes the hair on the back of my neck standup. THERE IS NO RELATIONSHIP BETWEEN THE FIREWALL AND THE CG!!!!! THE CGMUST BE IN THE CORRECT POSITION ON THE WING! Sorry to yell but the guys measuringfrom the other positions and then don't have the wing in the original locationsare playing with fire. I know this is a touchy topic on the group butI don't want to hear about one of you getting into a spin and not being ableto recover because your CG was aft of limit on the wing but the "correct" distanceaft of the zero datum, the firewall or the back seam of your aunt Gertiesbloomers. None of them matter if the CG is aft on the wing.Hank (Let the flames begin) J ----- Original Message -----

Original Posted By: walt evans
Walt,There is nothing better than high wing loading to give a good ride in turbulence.It is jsut like driving a car or flying the DC-9, load them up to gross andthey ride like a Caddy.Chris Bobka ----- Original Message -----

Original Posted By: hjarrett
Walt,How much dihedral in the wing on your ship with the bad ride in turbulence?Dihedral in excess of what is required can induce a bad ride. If you want, I willunbury an old post of mine and repost it on the subject.Chris Bobka ----- Original Message -----

Original Posted By: Christian Bobka
Chris,In answer to both questions,,,I built with zero dihedral, which has it's drawbacks.Actually after carefully rigging the wing with all it's struts, didn't takeinto account the "tightening everything" factor. So after covering and finalassy and cable tightening, I wound up with about 1/4" negative dihedral. Ohwell.BUT,,,If I have the right fuel in the nose tank, in still air, I can fly handsoff for miles.Guess it's the light wing loading. Just imagine if I built a Piet like the onein Fl. that weighed in at approx 850# empty. It would be typhoon worthy!walt evansNX140DL ----- Original Message -----

Original Posted By: hjarrett
Hank,After moving the wing back, my CG does fall in the last inch of the required envelope,but they are accurate numbers. Guess with light wing loading, this isthe nature of the beast ( like Chris brought up).The specs for CG, from Bernard are for dimensions on the wing, so in theory, whereever you put the wing, if the CG is right on the wing,,,the CG is right onthe wing.And as far as I know,,,the front seat is pretty much at CG. So I think the issueis more weight than CG?walt evansNX140DL ----- Original Message -----

Original Posted By: Jim Ash

Original Posted By: walt evans
Sounds like you are pretty close on CG if you located it based on the wing chord.I get worried about the guys that say "the plans say the CG is XX inches aftof the firewall and that's where mine is. Of course I moved the wing forwardyy inches and shifted the landing gear ZZ inches but dang it! The CG is justwhere the plans say, XX inches aft of the firewall!" Many builders don't understandthe wing is the thing. You don't want to think of it as moving thewing over the fuselage, think of it as moving everything else relative to thewing. You have to locate the wheel and CG locations relative to the WING.Glad you got it right. I still wonder about the change in pitch sensitivity atlower weight though. It should BOUNCE more in rough air but the elevator sensitivityshouldn't change. I need to go look at the factors that go into thepitch stability derivatives (never did like dynamic stability analysis).Hank ----- Original Message -----

Original Posted By: hjarrett
Hank,No, the pitch sensitivity doesn't seem to change. I said in my original postthat the yaw was affected. But how you put it in the below post best describesit,,,it BOUNCES more when it's lighter. It just plain "squirrellier" when light.Might have to fly with one of those inflatable "date" dolls, filled with sand :)walt evansNX140DL ----- Original Message -----

Original Posted By: walt evans
Use water, closer to the weight of a body and MUCH easier to get out of the frontpit by running a drain line. I can see it now, "Hey Walt, you musta scaredthat lady in your plane pretty bad. She hasn't moved for a half hour exceptto slowly slump in the seat and she is STILL wetting the ramp!"Hank ----- Original Message -----

Original Posted By: hjarrett
Hank,Great idea!!! :)walt evansNX140DL ----- Original Message -----

Original Posted By: walt evans
Get a "blow-up" doll that is fuel proof and the possibilities boggle the mind!"MAN!!! Walt must have that sucker REALLY LEANED! He's had her up there for HOURS!"OR...Want to try for an Atlantic crossing? It would sure take a lot out of your "passenger".Hank (Sick mind here)J ----- Original Message -----

Original Posted By: Les Schubert

Original Posted By: Michael D Cuy