Penton Xpress
09-04-2005, 02:19 PM
#1
Penton Xpress
Nat Penton (aka Voodoo Guru) now is Not the only one flying his Express design. I witnessed the first flight of Mr. Richard Lewis' Xpress powered by YS110.
Some specs on Richard's Xpress (yellow):
Length:78"
Span: 67"
Weight: 7lbs. 9oz.
Mr. Penton has been refining and flying this design for years. I understand now that Nat has outfitted his (green) current Express with a plettenburg for power.
Side Force Generator this....
p.s. Now I won't be the one with the strange looking pattern plane anymore! lol.
Some specs on Richard's Xpress (yellow):
Length:78"
Span: 67"
Weight: 7lbs. 9oz.
Mr. Penton has been refining and flying this design for years. I understand now that Nat has outfitted his (green) current Express with a plettenburg for power.
Side Force Generator this....
p.s. Now I won't be the one with the strange looking pattern plane anymore! lol.
09-04-2005, 08:48 PM
#3
Senior Member
RE: Penton Xpress
I met up with Nat a couple years ago in Pensacola Florida. Nat let me fly his 3D version. It was like 8lbs with a OS 91 2 cycle.
It was a really fun model to fly. We stayed at the flying field till dark playing with it. It was a really fun model to play with.
I would say this model had the most rudder control...not rudder authority but the ability to turn with rudder and control it...than any model I have ever flown.
Lots of models out there have really touchy rudders especially around neutral. Some guys look at this as a good thing. After all they don't need much rudder in rolling elements, and you don't need lots of rudder to hold knife edge. The problem is these rudders don't do much for you when you are trying to control the model in rolling turns or loops. I have flown many models that seem to have good rudder authority and they just can't turn the model on the last 1/4 of a 1 roll loop. Its almost like the rudder is getting blanked out. I played with a model last year that had this problem in spades. The rudder was effective in minor changes but when you needed it the only way to get the model to turn was to roll the wings and use the elevator to get the arc properly defined. Once you had the rudder and elevator working together you could get the model to turn but it just didn't like the spot where the speed was picking up and the wings were inline with the runway and only rudder was turning the model...It would always give a flat spot right there....It was tough thig to try and fly through. We worked really hard on the problem and the result was less rudder throw. As the surface was apparently stalling out.... Then you just din't have the amount of turn needed.
As the rudder deflection goes higher the model starts to loose its rudder authority or a better term is knife edge ability. This knife edge ability is the model flying on its side whether its coming straight at the ground or going through a rolling turn like a rolling circle. We see this in the size of rolling circles. If the model can't do them small and tight its because it can't turn tight enough. As you try to turn it tighter the drag means more power is needed and the result is the model is eating up ground faster and size of the circles gets bigger. What I think happens is as the rudder moves out to 10-20 degs the rudder becomes a drag inducing device and not a turning device. The change from 0-5degs of deflection and the change from 20-25 degs of deflection should be similar in terms of changing the rate of yaw. Nat's model didn't care if you already had 15 degs of rudder in it if you gave it 5 more degrees it would react and not grab or hook...rather it was a smooth escalation of the turn.
This model could do some amazing tight rolling turns and loops and was fully in control of the radius....You could also take it up and pinwheel it at the top of a stall turn where the model would just pivot around the wing tip for a full or nearly full rotation. It was cool!
A plane like Nat's is a joy to fly as it has a very good knife edge ability and can really turn the model well not just give a sensitive rudder. My personal opinion is it was really tough to see when flying sequence stuff...but it was soooooo light it amazing doing the 3D stuff.
We had a really good time with the model.
Something I will probably never forget...I think I should build one just for fun.
Troy Newman
It was a really fun model to fly. We stayed at the flying field till dark playing with it. It was a really fun model to play with.
I would say this model had the most rudder control...not rudder authority but the ability to turn with rudder and control it...than any model I have ever flown.
Lots of models out there have really touchy rudders especially around neutral. Some guys look at this as a good thing. After all they don't need much rudder in rolling elements, and you don't need lots of rudder to hold knife edge. The problem is these rudders don't do much for you when you are trying to control the model in rolling turns or loops. I have flown many models that seem to have good rudder authority and they just can't turn the model on the last 1/4 of a 1 roll loop. Its almost like the rudder is getting blanked out. I played with a model last year that had this problem in spades. The rudder was effective in minor changes but when you needed it the only way to get the model to turn was to roll the wings and use the elevator to get the arc properly defined. Once you had the rudder and elevator working together you could get the model to turn but it just didn't like the spot where the speed was picking up and the wings were inline with the runway and only rudder was turning the model...It would always give a flat spot right there....It was tough thig to try and fly through. We worked really hard on the problem and the result was less rudder throw. As the surface was apparently stalling out.... Then you just din't have the amount of turn needed.
As the rudder deflection goes higher the model starts to loose its rudder authority or a better term is knife edge ability. This knife edge ability is the model flying on its side whether its coming straight at the ground or going through a rolling turn like a rolling circle. We see this in the size of rolling circles. If the model can't do them small and tight its because it can't turn tight enough. As you try to turn it tighter the drag means more power is needed and the result is the model is eating up ground faster and size of the circles gets bigger. What I think happens is as the rudder moves out to 10-20 degs the rudder becomes a drag inducing device and not a turning device. The change from 0-5degs of deflection and the change from 20-25 degs of deflection should be similar in terms of changing the rate of yaw. Nat's model didn't care if you already had 15 degs of rudder in it if you gave it 5 more degrees it would react and not grab or hook...rather it was a smooth escalation of the turn.
This model could do some amazing tight rolling turns and loops and was fully in control of the radius....You could also take it up and pinwheel it at the top of a stall turn where the model would just pivot around the wing tip for a full or nearly full rotation. It was cool!
A plane like Nat's is a joy to fly as it has a very good knife edge ability and can really turn the model well not just give a sensitive rudder. My personal opinion is it was really tough to see when flying sequence stuff...but it was soooooo light it amazing doing the 3D stuff.
We had a really good time with the model.
Something I will probably never forget...I think I should build one just for fun.
Troy Newman
09-04-2005, 11:52 PM
#4
RE: Penton Xpress
Jim,
Sorry, have not heard anything from CCRCC. I have heard though that Roddy is staying somewhere around Baton Rouge. I am very concerned for the rest of those wonderful guys.....hope to hear something soon.
Troy,
Last year, I was lucky enough to fly Nat's Express as well. It's been said before, but Nat has been ahead of his time.
It takes some time to realize that the plane is really flying when in knife edge. This is different from forcing the fuse to support the plane through the air with an AOA that will support the aircraft.....and create horrible drag at slower speeds. The natural tendency to feed top rudder has to be re-learned because it needs so little during k.e. flight. I also was surprised by the smoothness with which I could perform a slow roll......guess I had preconceptions about the flight coordination/transition between level flight and k.e. (45° areas). Richard actually incorporated wing adjusters on his vertical fins (which are mounted on a very small small c.f. tube) to allow for fine trimming of the forward fins. He even comtemplated placing servos where the adjusters were to be located.....mixing them to the rudder....really don't think it needs it though.
I have recieved pictures of a YS63 powered express that is reporting the same flight characteristics in a 65"x65" size. AUW on this little version is said to be 4.5 lbs (yeeeeaaaahhhhhhhhhh). Flight was described as similar to a very smooth flying indoor foamie.
-mark
Sorry, have not heard anything from CCRCC. I have heard though that Roddy is staying somewhere around Baton Rouge. I am very concerned for the rest of those wonderful guys.....hope to hear something soon.
Troy,
Last year, I was lucky enough to fly Nat's Express as well. It's been said before, but Nat has been ahead of his time.
It takes some time to realize that the plane is really flying when in knife edge. This is different from forcing the fuse to support the plane through the air with an AOA that will support the aircraft.....and create horrible drag at slower speeds. The natural tendency to feed top rudder has to be re-learned because it needs so little during k.e. flight. I also was surprised by the smoothness with which I could perform a slow roll......guess I had preconceptions about the flight coordination/transition between level flight and k.e. (45° areas). Richard actually incorporated wing adjusters on his vertical fins (which are mounted on a very small small c.f. tube) to allow for fine trimming of the forward fins. He even comtemplated placing servos where the adjusters were to be located.....mixing them to the rudder....really don't think it needs it though.
I have recieved pictures of a YS63 powered express that is reporting the same flight characteristics in a 65"x65" size. AUW on this little version is said to be 4.5 lbs (yeeeeaaaahhhhhhhhhh). Flight was described as similar to a very smooth flying indoor foamie.
-mark
09-05-2005, 12:38 AM
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RE: Penton Xpress
It's great to see that Richard's got that thing flying.
Mark, are you guys coming to the Dallas contest? I understand you're flying Advanced now, that's awesome, we need some more people in advanced! Chuck tells me you're looking pretty good too. Looks like I'm going to have to learn to fly this Impact
If you come hopefully Richard can bring his Vodoo Express!
Keith B
Mark, are you guys coming to the Dallas contest? I understand you're flying Advanced now, that's awesome, we need some more people in advanced! Chuck tells me you're looking pretty good too. Looks like I'm going to have to learn to fly this Impact
If you come hopefully Richard can bring his Vodoo Express!
Keith B
09-05-2005, 09:37 PM
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RE: Penton Xpress
Glad to hear you'll all be there, should be a good Advanced contest.
You're right Brett, Advanced is much more fun than Intermediate.
Keith
You're right Brett, Advanced is much more fun than Intermediate.
Keith
09-06-2005, 10:28 AM
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RE: Penton Xpress
I suppose since this is MY (just a little reminder for flyintexan) airplane, I should post something here, even though the thread has been hijacked as a roll-call and thinly veiled trash talking for the Dallas Contest......
I got seven flights on it over the weekend and it is definately gonna take some getting used to both visually and flight characteristic-wise.
Troy's observation are right-on. The plane is flying in yaw rather that having a fat fusleage forced sideways through the air to create yaw. Knife edge flight requires only a hint of rudder and there is virtually no coupling until you put in a whole handful of rudder for a knife edge loop or a tight flat turn, and then it has a very slight proverse roll.
I'll start new thread with some construction photos L8r.
I plan to fly it in Dallas next weekend...[8D]
Richard
...I got seven flights on it over the weekend and it is definately gonna take some getting used to both visually and flight characteristic-wise.
Troy's observation are right-on. The plane is flying in yaw rather that having a fat fusleage forced sideways through the air to create yaw. Knife edge flight requires only a hint of rudder and there is virtually no coupling until you put in a whole handful of rudder for a knife edge loop or a tight flat turn, and then it has a very slight proverse roll.
I'll start new thread with some construction photos L8r.
I plan to fly it in Dallas next weekend...[8D]
Richard
09-06-2005, 02:04 PM
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RE: Penton Xpress
Troy thanks for your comments. The two airplanes in your photos now have wing changes. Eliminating the sweep eliminated roll with rudder, and slight pitch, in straight and level yaw. The had no couples in KE, even with hard rudder. Also lowering the AR improved stall characteristics. You need to fly them again !!
09-07-2005, 12:10 AM
#13
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RE: Penton Xpress
Some more information....
Attached are pictures of the YS63 powered Voodoo Express (VE) referenced above.
The model was created from plans drawn from pictures of Nat's VE3D and discussion with Nat. The only difference from Nat's design is the use of a single fin on bottom, and carbon tube braces on the stab. Nat's most recent versions of the VE have been what he calls his FAI and 3D versions; the 3D version having an equally tapered wing as opposed to straight trailing edge, larger elevators and larger fin area. Span and length are 65"x65" on mine, 78"x78" on Nat's. As Nat points out, using a lower AR wing may be advantageous, but the design is very good as-is.
The construction is: Foam wing and stab; all contest balsa; 1/8 spruce stringers (fuse); and some CF/end-grain balsa formers. The covering is Ultracote transparent light and regular. The construction methodology/design (i.e., minimal fuselage and thin ~9.5% airfoil) produce a very light airframe (yes, it is 4.5#).
I have flown Nat's FAI and 3D versions enough to understand their flight characteristics, and can say that Troy's description of the design's yaw response and how it differs from a conventional fuselage designs is right-on. It is not sensitive around neutral as are the current crop of widebodies, and it "carves" yawing turns instead of skidding around in the same way a loop responds to elevator input. My take on the reason for this is that the more a conventional the fuselage is yawed, the more it resists the yaw (and the more drag is created in trying to overcome this restoring force). This could be solved with more fuselage area ahead of the CG, but at the expense of a very sensitive yaw response and possible loss of direction stability. Nat's design "solves" this problem by concentrating the fuselage lift over the point it does the most good--the CG, and the induced drag is much less, which makes rolling turns/loops very easy.
Aside: I think the lack of pitch couple with the design (mine, Richard's or Nat's incarnations) is somewhat a validation of the concept that fuselage asymmetry has a lot to do with pitch couple in knife-edge.
My interest in building a copy of Nat's design was not so much for the "trick" flight characteristics that it provides, but rather it was to explore the potential for improving the F3A model. As part of this experimental process I also constructed an indoor foamie (pictured), testing the limits of side area relative to wing area; one needs to fly this one with "down" rudder in knife edge to maintain the desired angle of attack. Same result was obtained as in the IC versions in terms of yaw response and coupling.
There is no reason a pattern airplane has to look like an airplane. For our purposes, form should follow function. My assertion is that the more rolling turn and loops come into the FAI pattern, the more planes will look like a Voodoo Express. Look at the OXAI Pinna. Electric power makes convergence to a pure function-driven pattern design more feasible as the fuselage no longer needs to be designed around containing the IC engine and its exhaust system.
Regards,
Andre
Attached are pictures of the YS63 powered Voodoo Express (VE) referenced above.
The model was created from plans drawn from pictures of Nat's VE3D and discussion with Nat. The only difference from Nat's design is the use of a single fin on bottom, and carbon tube braces on the stab. Nat's most recent versions of the VE have been what he calls his FAI and 3D versions; the 3D version having an equally tapered wing as opposed to straight trailing edge, larger elevators and larger fin area. Span and length are 65"x65" on mine, 78"x78" on Nat's. As Nat points out, using a lower AR wing may be advantageous, but the design is very good as-is.
The construction is: Foam wing and stab; all contest balsa; 1/8 spruce stringers (fuse); and some CF/end-grain balsa formers. The covering is Ultracote transparent light and regular. The construction methodology/design (i.e., minimal fuselage and thin ~9.5% airfoil) produce a very light airframe (yes, it is 4.5#).
I have flown Nat's FAI and 3D versions enough to understand their flight characteristics, and can say that Troy's description of the design's yaw response and how it differs from a conventional fuselage designs is right-on. It is not sensitive around neutral as are the current crop of widebodies, and it "carves" yawing turns instead of skidding around in the same way a loop responds to elevator input. My take on the reason for this is that the more a conventional the fuselage is yawed, the more it resists the yaw (and the more drag is created in trying to overcome this restoring force). This could be solved with more fuselage area ahead of the CG, but at the expense of a very sensitive yaw response and possible loss of direction stability. Nat's design "solves" this problem by concentrating the fuselage lift over the point it does the most good--the CG, and the induced drag is much less, which makes rolling turns/loops very easy.
Aside: I think the lack of pitch couple with the design (mine, Richard's or Nat's incarnations) is somewhat a validation of the concept that fuselage asymmetry has a lot to do with pitch couple in knife-edge.
My interest in building a copy of Nat's design was not so much for the "trick" flight characteristics that it provides, but rather it was to explore the potential for improving the F3A model. As part of this experimental process I also constructed an indoor foamie (pictured), testing the limits of side area relative to wing area; one needs to fly this one with "down" rudder in knife edge to maintain the desired angle of attack. Same result was obtained as in the IC versions in terms of yaw response and coupling.
There is no reason a pattern airplane has to look like an airplane. For our purposes, form should follow function. My assertion is that the more rolling turn and loops come into the FAI pattern, the more planes will look like a Voodoo Express. Look at the OXAI Pinna. Electric power makes convergence to a pure function-driven pattern design more feasible as the fuselage no longer needs to be designed around containing the IC engine and its exhaust system.
Regards,
Andre
09-08-2005, 01:01 PM
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RE: Penton Xpress
I do not currently have any plans of mine that would be suitable for anyone except me to build from. The overall fuse shape was CAD designed. but all other details were penciled on the CAD printout of the top and side views...although I nevr intended to produce plans, perhaps when I get some time I could endeavor to produce a useable set of plans...
Richard
Richard
02-17-2006, 11:28 PM
#16
RE: Penton Xpress
I realize that it has been quite some time since we last posted on this thread, but we have actually been slowly working on developing a set of accurate plans for Mr. Penton and Mr. Lewis' most up to date 2M express. Some of the minor changes that Nat suggested for Richard turned out to be right on target. If in doubt, please read Troy's post.
Richard is currently building another Express and the formers and other various parts have been cut using our semi-developed plans. This should allow to us to be reasonably certain that most everything is right on the plans. I must say however, that we have discovered that in printing at Kinko's using a pdf file, we have found some very minor scaling issues. These have been large enough to be a problem as of yet.
For those that are interested in the plans, please bear with us, we want them to be right on the first print. I thought I would keep the thread going from time to time with images of our development of the 3D model and subsequent 2D plans.
-mark
First, we created a decent (simple) computer model of the YS110 on a hyde mount...3" FAI spinner.
Richard is currently building another Express and the formers and other various parts have been cut using our semi-developed plans. This should allow to us to be reasonably certain that most everything is right on the plans. I must say however, that we have discovered that in printing at Kinko's using a pdf file, we have found some very minor scaling issues. These have been large enough to be a problem as of yet.
For those that are interested in the plans, please bear with us, we want them to be right on the first print. I thought I would keep the thread going from time to time with images of our development of the 3D model and subsequent 2D plans.
-mark
First, we created a decent (simple) computer model of the YS110 on a hyde mount...3" FAI spinner.
05-17-2006, 01:25 AM
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RE: Penton Xpress
This post falls under the "better late than never" category...
With loads of help from flyintexan, We have finally gotten the plans for the Voodoo Express 2 done...the details for acquiring the plans can be found at:
www.insightrc.com
Click on links to the Voodoo Express 2 page.
I've got alot more pics/info/history to publish on this page, but it is good enough for now to get the plans out there to interested people.
Please don't PM me here on RCU regarding these, I'd rather receive e-mails at:
[email protected]
Richard
With loads of help from flyintexan, We have finally gotten the plans for the Voodoo Express 2 done...the details for acquiring the plans can be found at:
www.insightrc.com
Click on links to the Voodoo Express 2 page.
I've got alot more pics/info/history to publish on this page, but it is good enough for now to get the plans out there to interested people.
Please don't PM me here on RCU regarding these, I'd rather receive e-mails at:
[email protected]
Richard
