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Jun 05, 2019, 01:53 AM
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>> the XLT is an untamed, overweight, under engineered, complex to build design.<<

Now you tell me.
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Jun 05, 2019, 01:59 AM
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Quote:
Originally Posted by bradl7112
My suggestion is to run it with a strong .60/61 on the pipe, and fly it as designed. A Rossi or YS ( as well as others on the pipe)will pull this extremely well.... Add a little weight to the nose, keep it as is, pipe it and I believe you’ll love it... I’ve seen these aircraft, competing, back in the day, heavy...12lbs and still doing very well. Besides, no one competes with these designs anymore.....Put the gear up and enjoy it .

PS I just read one of your later threads about over powering your a/c.....so I understand your initial motivation.
Thanks. Yes I have been schooled on over powering a plane. When ever a plane calls for a 40 size engine I stuff a 60 in it. The only thing was that the 10cc 2 stroke was the limit for competition so I was stuck. Now that I don't compete and just play around all my 60 size plane have bigger engines on them.

That said I did some comparisons with different engines. The interesting thing is that the Rossi 60 on pipe is definitely more powerful than all the .75's (Super Tigres) and .77s (MVVs) I am using. The only difference is that the .75s and .77s are actually lighter than the Rossi 60s by 2 ounces and the throttle curves are more linear and not as peaky.
Jun 05, 2019, 02:14 AM
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[QUOTE=RC YEAGER;42016469]
Quote:
Originally Posted by doxilia
As a side note, the Deception was born of the Cutlass, Saturn, Compensator and Boolegger lineage.

The Deception (kitted by Bridi but designed by Jim Kimbro) did evolve from the Compensator-Bootlegger lineage. The Compensator itself evolved from the Nutcraker flown for a short while by Rhett Miller's mentor, Jim Kirkland. And the Nutcracker itself was an "Americanized" Japanese Fuji.

However... it is my understanding that the Cutlass, Sweetater, Saturn lineage is sort of a different one all together. I say sorta, because all these guys back then modified and/or borrowed details from each other designs in search of better performace.
It is very interesting (at least to me) to dive into the various design philosophies and lineage of the pattern planes from say 1959 to the 90's. Various school of thoughts on airfoil thickness, airfoil configurations (Jim Kirkland's Mustang X has a progressive foil that goes from fully symmetrical to semi symmetrical. Bruno Giezandanner's Marabu has a progressive foil that goes from semi symmetrical to full symmetrical. Opposite thoughts except the Marabu has 2 degree washout).

Besides having so many classic/not so classic pattern planes to build and fly there is one project I really want to engage in before I die. I want to build a series of ugly stick flavor box fuselage as a base (So there is no real aerodynamics consideration on the fuselage except that it is a draggy design) and mate that to a variety of wings, airfoils, tail feather configurations, tail moments etc. to test some of the flight characteristics.

The Sky Aviation Marabu is actually the reason that is putting the idea in my head. As I said before the wing has a progressive foil going from semi symmetrical root to fully symmetrical tip with washouts. The rudder is all the way on top of the fuselage. There is a few degrees of dihedral. So conventional wisdom will say that the plane will have some sort of roll couple to rudder input. However that plane is exhibiting some of the most pure knife edge and stall turn characteristics. The plane also has a similar tail wiggle like the Kwik Fli. The Triton by Jim Kirkland also has a top rudder and that plane has all kinds of roll couple with rudder input. However the Triton does not have a tail wiggle. Go figure.
Jun 05, 2019, 02:24 AM
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>>As a side note, the Deception was born of the Cutlass, Saturn, Compensator and Boolegger lineage. Different beasts from the Bridi designs in several ways I won’t elaborate on.

In contrast, the XLT was born of the Kaos, Dirty Birdy, UFO, Mama Mia lineage. I believe Joe discovered some of the issues inherent with the XLT and refined it shortly thereafter in the more compact lighter Escape which Cunningham evolved into the Great Escape. I believe the latter solves some of the flight issues associated with both the XLT and Escape.<<

Ok David, you are losing me a bit here. I understand the Deception and XLT may look similar simply because of the tuned pipe tunnel in the canopy but they are designed by two different persons. Deception was designed by Jim Kimbro and XLT by Bridi. They are different size also so I would imagine their lineage to be different.

When you said the Deception was born out of the Cutlass, Saturn, Compensator and Bootlegger and I got confused. Correct me if I am wrong but aren't those four very different planes and from different era? I know Saturn is a large four stroke turn around designed by........I forgot who but a more modern design. Cutlass was a much older classic design by Don Coleman? before the Kwik Fli? Compensator was by Rhett Miller. Bootlegger, damn I cannot remember that one either but that seems to be related to the Compensator.

Then the Kaos, Dirty Birdy, UFO are all Joe Bridi's design.

As mentioned before I only know a few of the American designs. I mostly kept track of the European and Asian designs while growing up because of the information available.
Jun 05, 2019, 07:26 AM
Registered User
Seismic,
There are two pattern Saturn designs: the first by Ivan Kristensen back in the early '70s (cross flow ported engines) and similar to the Cutlass in appearance; the second Saturn appeared in the 90's and was design by a guy named Sam ???? (can't remember his last name).
I would consider Jim Kirkland's Intruder design to be one of the original ancestors of modern pattern design.
Bridi's XLT wouldn't be such a 'pig' if it was design to fly and used contest balsa. The quality of his kit balsa was quite variable and rarely very light (not Japanese kit quality). The XLT has a very large stab (probably too large) sheeted with 3/32 balsa (if the stock sheeting from the kit was used it was probably in the 8 lb density ballpark) and your airplane was painted. The XLT does have a lot of wing area (around 850"sq if memory serves); at 11 pounds it will be right at the 30ounces per square foot wing loading which, in my book, is the very upper limit of acceptable..
It is a nice looking airplane and I agree with all the advice from above: get the strongest 61, add the least amount of weight to get it balanced and fly it!!
Jun 05, 2019, 10:16 AM
DavidsPlanes
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Hansen,

Yes, what Will said.

Actually I was being a little “loose” in stating the lineages considering the Bootlegger came out after the Deception. What the lineage has in common, in particular, and it perhaps dates further back than the Nutcracker (eg to the Citron) is the specific unusual airfoil used in several of these models. As far as I know, the Nutcracker, Cutlass, Saturn, Sweetater, Compensator, Deception (and it’s siblings) and Bootlegger all shared the same “class” of unusual symmetric wing airfoil. I don’t believe they are identical but they all derived design inspiration from their predecessors. If one reads the feature articles of the models, the authors will often make reference to one or more designs in the lineage. While airfoil is not as critical to these classics as perhaps other design aspects (planforms, moments, decalage, etc), it does “bind” their heritage.

Similarly, I’d say that Bridi’s designs follow what appears to me to be a fairly independent evolution in that Joe was changing the design as rules and requirements of the time dictated relying more on his previous designs that those of others. Prettner and Matt also did this in a way that’s perhaps easier to follow as their designs might be more “world famous”. While Joe changed the moments and planforms, he didn’t change his airfoil a great deal with all his designs having “NACA like” airfoils of various thicknesses. Notably the thickness didn’t follow a decreasing pattern as one might expect since the Kaos had a rather thick airfoil (~18%) and the Dirty Birdy lowered this to about 15%. But then in the subsequent UFO it grew back again to 18% as did the stab thickness (10 -> ~12%). I believe the XLT, Mama Mia and Escape stayed with the thicker airfoils. Perhaps more importantly, the max thickness of the foils is further back in the Deception “line” and I believe the thickness might also be transitioning in some designs with it going forward toward the tip (eg Deception inspired Hip Pocket).

In any event, one could continue down this “detour” conversation but in my view, and although I never met him, Joe strikes me as having been a more pragmatic experimental designer who “sketched” on paper and proofed in the air whereas people like Coleman (Cutlass), Kimbro (Deception) and Helms (Bootlegger) strike me as engineer type personalities who proofed on paper and verified in the air. If you read the articles on these various designs (and others by the same authors), the heritage and design philosophy comes through.

But none of this will help to get your XLT powered up, balanced and flown.

I tend to agree with the others though. Getting a 60-90 RE engine in there and a pipe is the way to go. A heavy battery as far forward as possible (side of the retract bay?), maybe a heavy prop nut of sorts, heavy APC prop and TT spinner and then use the lightest elevator mini servos insuring they’re forward of the CG. The light Rx can always go behind the CG if you run out of space in the front wing bay. Oh yes, use a Kraft nose wheel and light soft main wheels (eg Dave Brown Lite Flite).

David
Last edited by doxilia; Jun 05, 2019 at 10:26 AM.
Jun 05, 2019, 11:35 AM
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>> There are two pattern Saturn designs: the first by Ivan Kristensen back in the early '70s (cross flow ported engines) and similar to the Cutlass in appearance; the second Saturn appeared in the 90's and was design by a guy named Sam ???? (can't remember his last name).<<

Thanks for the reminder. Ivan Kristensen rang a bell in my memory bank. I was thinking Canada but couldn't remember the name. I only vaguely remember the Saturn name in a pattern plane but not much else.

>> I would consider Jim Kirkland's Intruder design to be one of the original ancestors of modern pattern design.<<

I have to look into the Intruder a bit more. Always wanted to build one of those.

>> Bridi's XLT wouldn't be such a 'pig' if it was design to fly and used contest balsa.<<

I am sure there are ways to work around the design if built properly.

>>The quality of his kit balsa was quite variable and rarely very light (not Japanese kit quality).<<

I was not very impressed with most American kits back in the days. They were pretty bad compare to the Japanese kits (Yoshioka, MK, IM, Digicon etc.)

>> The XLT has a very large stab (probably too large)<<

That's one thing I noticed. The stab is huge.

>>The XLT does have a lot of wing area (around 850"sq if memory serves); at 11 pounds it will be right at the 30ounces per square foot wing loading which, in my book, is the very upper limit of acceptable..<<

Yes. 845 is what the specs said. I prefer 25 ounce as the high side personally. I usually don't bother with 30 ounce loading designs. That's one reason why I don't fly too many war birds.

>> It is a nice looking airplane and I agree with all the advice from above: get the strongest 61, add the least amount of weight to get it balanced and fly it!!<<

That may well be what I will do eventually. For the time being it is being "aged" while I think about it. Got a few more other projects I want to finish first.
Jun 05, 2019, 11:57 AM
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>> all shared the same “class” of unusual symmetric wing airfoil.<<

I have always been intrigued with the various airfoils. I have always wondered how precise the pattern designers designed the airfoils (like the sailplane community) or were they simply a lot of french curve specials.

>>Similarly, I’d say that Bridi’s designs follow what appears to me to be a fairly independent evolution in that Joe was changing the design as rules and requirements of the time dictated relying more on his previous designs that those of others.<<

I believe most designers were following similar thoughts. Pattern plane designs evolved rather slowly and mostly because of rules change. The exceptions are rare especially later in the years. There were more room for experiments with original ideas in the early years.

>>In any event, one could continue down this “detour” conversation<<

"Detour" can be fun. There is only so much that we can talk about an overweight XLT.

>> but in my view, and although I never met him, Joe strikes me as having been a more pragmatic experimental designer who “sketched” on paper and proofed in the air whereas people like Coleman (Cutlass), Kimbro (Deception) and Helms (Bootlegger) strike me as engineer type personalities who proofed on paper and verified in the air. If you read the articles on these various designs (and others by the same authors), the heritage and design philosophy comes through.<<

Yes those are definitely two distinct approaches. I wonder how many of those older designers were actual aero engineers. I think Don Lowe is/was an aero engineer. Pattern flyers/competitors were/are more the "showman" type personalities. They are/were like the formula 1 car drivers with motor skills and quick hand eye coordination rather than the engineering type that sits and crunch numbers. Most designs were probably borne out of "experience" and educated guesses with real world trial and error.

>>But none of this will help to get your XLT powered up, balanced and flown. <<

No and I also have some ideas on how to get this XLT balanced, powered and flown and unfortunately my ideas are more functional rather than form. Besides the XLT is really not one of my favorite design so it is more a sport plane to me. I am not going to put too much emotional debt into it.

>>I tend to agree with the others though. Getting a 60-90 RE engine in there and a pipe is the way to go. A heavy battery as far forward as possible (side of the retract bay?), maybe a heavy prop nut of sorts, heavy APC prop and TT spinner and then use the lightest elevator mini servos insuring they’re forward of the CG. The light Rx can always go behind the CG if you run out of space in the front wing bay. Oh yes, use a Kraft nose wheel and light soft main wheels (eg Dave Brown Lite Flite).<<

A 90 size engine is almost a given. I can't get nitro locally so the YS is out of the question. So it will either be a Rossi 90, Dub Jett 90 or a Nova Rossi 90. Rear exhaust is going to hard to find. Heavy battery is not too hard. No heavy prop nut though I just don't like them. I have an idea since the 90 is going to be longer than the Rossi 61 I can machine a brass nose ring because there will be a gap between the back of the spinner and the nose ring. Moving all the servos forward is a must. Elevator pushrod is in but I don't like them so I will modified. Not sure if I will go with one or two servos but they will be forward of the CG. Rx never come into play with regards to CG since they are so damn light nowadays. Unfortunately I may be sacrilegious and change this to a tail dragger fixed gear. No retracts can survive our flying field for long no matter how gentle I land the plane.
Jun 05, 2019, 05:17 PM
Registered User
Here's the Flying Models review of the XLT from the August of '85 issue. I think Joe first competed with it in '82; so not exactly timely...

I have a Jett 100L (rear exhaust) it is a beautiful piece of machinery, but pricey. It is also very light, basically about the same weight as a strong 61. The mounting dimensions are exactly the same as the OS engines which is convenient. I don't know if Dubb is making rear exhaust engines at the present time, his website is bit unclear about this; so I would send him an email inquiry if you are interested in going in that direction.

As for pattern design origins, it is difficult to determine. Publication dates are pretty inaccurate as they really reflect the competitive success of a design and not the first appearance of the model. A better source would be contest results, but only the Nationals results published in the AMA magazines provide consistent data. Art Schroder's columns in the early '70's M.A.N. are pretty informative as he was a pattern competitor and Peter Chinn's 'Foreign Notes' also have some good information. The USA really had 3 'hot beds' of pattern: the southeast (Kirkland, Edwards, Whitely, Chidgey, Miller, Helms, etc.); Ohio (Lowe, Brown, Ullery, Koger, McConville, Combs, etc.); and southern California (Kraft, Bridi, Kimbro, Hyde, etc.). The p[ilots from each area would see each other at local contests pretty regularly. Back in the 'good old days' (especially the '70s and early 80s) 10-15 'local' contests was the norm and a lot of brainstorming occurred there. I wish that Ron Chidgey would give his perspective on the history of pattern competition. His designs range from the Tiger Tail I to the Typhoon 2000 and span 30 years of pattern competition (about 1970 to 2000) and reflect the enormous changes that pattern underwent in that time frame.

I am constantly amazed at the plethora of pattern kits currently available spanning the late 60's to about 2007.
Jun 05, 2019, 05:43 PM
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>>Here's the Flying Models review of the XLT from the August of '85 issue. I think Joe first competed with it in '82; so not exactly timely...<<

Thanks I downloaded them for reading later.

>>I have a Jett 100L (rear exhaust) it is a beautiful piece of machinery, but pricey. It is also very light, basically about the same weight as a strong 61.<<
Hahahaha......I need nose weight.

>> The mounting dimensions are exactly the same as the OS engines which is convenient. I don't know if Dubb is making rear exhaust engines at the present time, his website is bit unclear about this; so I would send him an email inquiry if you are interested in going in that direction.<<

I just sent him an email inquiry as to whether he can do a rear exhaust 90 and what pipe and header to use. Also since I cannot get nitro locally I am mixing my own FAI fuel. So I need the engine to handle that in the idle and transition. Should be not too much of a problem. Probably just increase the compression ratio a little bit.

>>As for pattern design origins, it is difficult to determine. Publication dates are pretty inaccurate as they really reflect the competitive success of a design and not the first appearance of the model. A better source would be contest results, but only the Nationals results published in the AMA magazines provide consistent data. Art Schroder's columns in the early '70's M.A.N. are pretty informative as he was a pattern competitor and Peter Chinn's 'Foreign Notes' also have some good information. The USA really had 3 'hot beds' of pattern: the southeast (Kirkland, Edwards, Whitely, Chidgey, Miller, Helms, etc.); Ohio (Lowe, Brown, Ullery, Koger, McConville, Combs, etc.); and southern California (Kraft, Bridi, Kimbro, Hyde, etc.). The p[ilots from each area would see each other at local contests pretty regularly. Back in the 'good old days' (especially the '70s and early 80s) 10-15 'local' contests was the norm and a lot of brainstorming occurred there.<<

Thanks. Great summary. That's one reason why the designs overlap each other so much. I am sure there are a lot of sharing of ideas.

>> I wish that Ron Chidgey would give his perspective on the history of pattern competition. His designs range from the Tiger Tail I to the Typhoon 2000 and span 30 years of pattern competition (about 1970 to 2000) and reflect the enormous changes that pattern underwent in that time frame.<<

Yeah, Wolfgang Matt is another one but that is in another language.

>>I am constantly amazed at the plethora of pattern kits currently available spanning the late 60's to about 2007.<<

Too many planes and too little time.
Jun 05, 2019, 08:53 PM
Registered User
Seismic think Sam Turner of either North or South Caroline did the second Saturn design. BTW guys the old Eastern bias shows up again. Guys like Steve Stricker and Dean Papas and others with dozens of contest up and down the east coast existed. Give the devil it's due!!
Jun 05, 2019, 10:37 PM
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Quote:
Originally Posted by bkanter
Seismic think Sam Turner of either North or South Caroline did the second Saturn design. BTW guys the old Eastern bias shows up again. Guys like Steve Stricker and Dean Papas and others with dozens of contest up and down the east coast existed. Give the devil it's due!!
Thanks. I remembered Ivan Kristensen with the Saturn and Summit, Same Turner and the Pursuit but I didn't remember Sam and the Saturn.
Jun 05, 2019, 10:55 PM
DavidsPlanes
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Curious you mentioned Ron Chidgey Will. I suspect that Chidgey’s Tiger Tail was born from Kirkland’s Citron in what he called a taper wing Citron (the Citron was constant chord). Even back then, Chidgey finished his tapered Citron in the classic TT scheme and the heritage is well apparent.

Interesting article on the Citron as Kirkland professes himself as a “cut and crash” designer who used his full scale pilot experience to design his models and didn’t consider himself an aerodynamicist per se.

David
Jun 05, 2019, 11:03 PM
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>>Curious you mentioned Ron Chidgey Will. I suspect that Chidgey’s Tiger Tail was born from Kirkland’s Citron in what he called a taper wing Citron (the Citron was constant chord). Even back then, Chidgey finished his tapered Citron in the classic TT scheme and the heritage is well apparent.<<

The Beachcomber had constant chord wing and that evolved into the Citron. When the Citron was produced by Lanier it had tapered wing also.

>>Interesting article on the Citron as Kirkland professes himself as a “cut and crash” designer who used his full scale pilot experience to design his models and didn’t consider himself an aerodynamicist per se.<<

Jim Kirkland was an Air Force pilot. Many of his designs had some sort of scale look to them. Like the Mustang X, A-6, Triton etc. Even the Citron had a P51D style canopy. The Nutcracker started to deviate from a full scale look alike but probably because it was borrowed from the Fuji.
Jun 06, 2019, 02:14 AM
Registered User
Slight side track..
Will,
Just a reminder of the Northeast ‘hotbed’ designers and fliers that influenced the sport ... ...folks like Jim Martin, Dennis Donahue, Tony Bonetti, George Buso as well as Pappas later on..... led the way for many in the USA and influenced pattern design and flight.

Brad
Last edited by bradl7112; Jun 06, 2019 at 02:30 AM.


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