Lightning-List Digest Archive

Wed 08/06/08


Total Messages Posted: 6



Today's Message Index:
----------------------
 
     1. 04:02 AM - Re: kitplanes (Brian Whittingham)
     2. 09:03 AM - Re: kitplanes  (N1BZRich@AOL.COM)
     3. 03:28 PM - Re: kitplanes (Brian Whittingham)
     4. 05:09 PM - Buz and Brian (Tex Mantell)
     5. 07:03 PM - Re: Buz and Brian (N1BZRich@aol.com)
     6. 09:16 PM - Re: kitplanes (N1BZRich@aol.com)
 
 
 


Message 1


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    Time: 04:02:23 AM PST US
    From: Brian Whittingham <dashvii@hotmail.com>
    Subject: kitplanes
    Tex=2C Well....I think that he mentions the early Lightnings as having neutral to slight negative stability. I can tell you that I have never experienced this=2C but it would have been more what I would call a neutral to slight positive stability in pitch from the loadings that I have seen. It was als o hard to find stick center position without looking. I do think that the changes that have been made will result in a better overall product for cli ents. I really liked the feel of the original as it felt more like a fight er. I asked a guy who has worked testing planes for a long time what he th ough. Eric replied: "Wow=2C they couldn't have made a bigger change unless they trimmed the hor izontal.Lot's of different effects come into play here. In an tab-trimmed aircraft=2C there is a completely different interaction between stick-free stability=2C stick-fixed stability=2C and stick-force-gradient than there i s in a bungee system. Because bungees and springs yield more force for mor e deflection=2C the bungee system actually has better stick-free stability at large gust upsets=2C but tends to have low breakout and center forces. I can understand how this would not bother an experienced pilot who likes l ight stick forces. The trim tab set up is better for the 20 to 50 hour/yea r pilots that make up most of the market. As to the CG change=2C I cannot tell without flying the two aircraft side-by-side. I have seen very small CG changes make huge differences in stick force gradient in some aircraft =2C especially if they had a CG close the wing aero center=2C but well forw ard of the static stability point. This happens on lots of GA aircraft whe re the tails have been sized generously for low time pilots. The issue is that while the aircraft is stable at an aft CG=2C it doesn't "feel" very co nfidence inspiring. A good test pilot will set down=2C look at the longitu dinal stability=2C and then decide how deep he wants to explore this region .So the trim tab system gave you most of the breakout force and centering i mprovement=2C while the CG change may have done the most for the full-trave l-full-G-range stick force gradient. That's how the second order stability and control equations come out. Again=2C I'd have to have either the raw data or design the control test points myself to be certain and assign figu res of merit.I used to be a fan of down-springs as a way of increasing stic k-force gradient for lower time pilots in high performance aircraft. The p roblem is they swap a positive G longitudinal stability issue for a negativ e one. We all fly negative in heavy turbulence. Recently=2C I've shifted my emphasis towards servo and anti-servo tabs and their effects. I am stil l a fan of bungees to coordinate roll and yaw=2C as on the Mooney. The air craft can still be slipped and skidded=2C it just takes more force and make s up for lazy feet in the pattern.By far=2C the best combination of feel=2C flying qualities=2C stability=2C and control comes from a trim-able horizo ntal. It is the most expensive and mechanically complex. Second most comp lex is the manual trim tab system=2C followed by the all-electric. Simplis t is no system=2C bungees are common on sailplanes where people like a ligh t feel and max speeds are low." I think that the above would be a fair assessment. I was with Buz on not t hinking the change in C.G. in this case had much to do with the stability i mprovement=2C but as you read above=2C even a slight difference can make a large improvement on some aircraft. Keep in mind that there are many aircr aft built with neutral to slightly positive stability. This doesn't mean t hat you are going to loose control of the aircraft when we talk about stabi lity. What it does mean is what you read about trimability. It also means that you have to hand fly the airplane more b/c the stick would pretty muc h stay at whatever pitch you put it at. I have not personally evaluated th e new demo=2C but believe what the author reported and remind everybody tha t if they have an early Lightning and would like to make these changes they can be made to an already built and flying plane. I also want to remind e verybody that it's not a recall type of item=2C it doesn't need to/have to change. Some of these changes were to allow a low time pilot to be able to easily and confidently fly the airplane. It's a qualitative change based on "feel". Hope this helps=2C Brian W. From: wb2ssj@earthlink.netTo: Lightning-list@matronics.comSubject: Lightnin g-List: kitplanes Date: Tue=2C 5 Aug 2008 21:16:06 -0400 Just finished reading the Magazine with Nick sitting in the left seat by hi mself=2C which was strange. The article left me puzzled and confused. I wo uld be interested in others comments about the content and overal l tone of the review of the Lightning. Tex _________________________________________________________________ Got Game? Win Prizes in the Windows Live Hotmail Mobile Summer Games Trivia Contest http://www.gowindowslive.com/summergames?ocid=TXT_TAGHM


    Message 2


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    Time: 09:03:36 AM PST US
    From: N1BZRich@AOL.COM
    Subject: Re: kitplanes
    Tex and all, Sorry, this will be a little long, but I will expand a little more on what I wrote on the subject while I was at OSH. Brian covered a lot in his recent message. Overall, I thought the article was good in that it painted Arion as a progressive or proactive company that is willing to change the product to make it better for the customers. However, please note that Nick did not change the trim system because of the draft flight review that the author wrote after flying the first demo Lightning and Linda's aircraft. The new trim system was already on Nick's list of changes to make, but perhaps the timing of the trim change was accelerated because of the upcoming article. Once the new demo had the new trim system, the author liked the way the new 2008 demo flew. Of course "better" is a relative term. I liked the light stick forces and stick force per G that the prototype and original demo had (and Linda's airplane). However, on long cross country flights it can be more work if you have to hand fly it all the time. As to the neutral pitch stability issue, it was the bungee trim system that makes the airplane fly like it has those characteristics. Let me explain: First neutral pitch stability is a great situation for a fighter or an aerobatic aircraft (most of my flying time is in these type aircraft) because both of them are often rapidly going from high speed to low speed and then back to high speed again, many times during a dog fight or aerobatic sequence. If you had to constantly re-trim the aircraft with each speed change you would wear out the trim button. Just kidding, but your work load would be high as you trimmed the aircraft to keep stick forces low. So they are designed to always keep low stick forces, but in doing so, it becomes a bit touchy (very light pitch forces) if you are not used to flying that type of aircraft. If you current Lightning or Esqual pilots with the bungee trim system want to test this out, pay attention to which way you really have to trim your aircraft as you change speeds. A normal aircraft will need more nose up trim as you slow down and more down trim as you speed up. The bungee system actually requires very little trim as you change speeds and, depending on how you have them adjusted, can actually require the reverse of this. Meaning as you slow down you will need nose down, not nose up. Weird but true. Why, because the bungee that attaches directly to the up elevator push / pull tube becomes more effective as you slow and there is not as much airflow over the elevator holding it in position. Therefore, as you slow, the bungee is able to pull more and more up elevator. Makes the airplane act like it has an aft CG. (Note, this is only with flaps up. With flaps down, you are now flying a new wing and the bungees generally will not completely trim off all forces.) So the negative pitch stability that the author mentioned comes from the fact that when the aircraft (with the bungee system) is slow and you pull back on the stick and then let go, it will not recover to the previously trimmed flight condition, it will continue to pitch up by itself because the bungee can pull more and more up by itself as there is less airflow over the elevator to keep it in trim. Try as hard as I did to diagram the system to the author and draw pitch stability curves, he was convinced that it was a CG problem even though the three Lightnings he flew were all at about the same CG. His comment was that we must have weighed the aircraft wrong or miss-calculated the Cg. When you do the pitch up maneuver (pull pack on the stick and let go) with the new trim system the airplane will return to the previously trimmed flight condition (airspeed) thus showing good pitch stability. So, the one thing that I do not agree with is the author's thought that the "better flying qualities" of the new demo has to do with moving the CG more forward. To reiterate, the change to the new electric trim system is what made the change, because the three airplanes he flew had the same CG (within a hair of the same - certainly not enough to make a major change like he reported) when he flew them. I kind of hate to disagree with him because after many emails, many phone calls, and flying with him in Linda's airplane, he has become a friend (even though he is an ex Navy "heavy" driver). He does however, have some knowledge in his Navy "Noggin". Heck, world record holder Earl (also ex Navy) knows him, so that in itself is a positive thing. Overall a great guy to talk to and share war stories and hangar talk with. So my bottom line is that it is a good article, but I do hope readers will read the entire article and not just the first part. As to Nick flying in the right seat, all good fighter pilots want the stick in the right hand and the throttle in the left hand. Blue Skies, Buz **************Looking for a car that's sporty, fun and fits in your budget? Read reviews on AOL Autos. (http://autos.aol.com/cars-BMW-128-2008/expert-review?ncid=aolaut00050000000017 )


    Message 3


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    Time: 03:28:42 PM PST US
    From: Brian Whittingham <dashvii@hotmail.com>
    Subject: kitplanes
    The one thing=2C from my experience that I would like to disagree with=2C a fter flying several different Lightnings was the "negative static stability " remark. I have not flown at all C.G. combinations=2C but I have flown at a similar weight and C.G. range based on fuel and pilot and passenger weig hts. In my experience the aircraft never showed even a slight negative sta tic stability characteristic as this would be indicated if you were to pitc h up and let go of the stick that the aircraft would continue to pitch up. I never saw this. It would either slowly come back to level through a ser ies of oscillations or stay wherever you let go of it. I kind of liked thi s. I haven't flown a lot of fighters like Buz=2C but I have flown some aer obatic planes. It's interesting when you can just put the nose where you w ant it=2C basically fly hands off and speed up or slow down while doing so. If it were negatively static stable you would never be able to fly the pl ane hands off as it would constantly be wanting to change pitch regardless of airspeed or trim. Now what may appeal to some builders about the bungee system is that it is probably a better setup to dampen out turbulence. You folks out west may w ant to think about keeping that. You east coast and sunday flyers or low t ime pilots will probably love the standard trim tab. Still=2C he did come up with the same conclusion as I did: Love to fly the Lightning and the co mpany is doing a good job making their product better for the customers. M y .02 Brian W. From: N1BZRich@aol.comDate: Wed=2C 6 Aug 2008 12:02:55 -0400Subject: Re: Li ghtning-List: kitplanes To: lightning-list@matronics.com Tex and all=2C Sorry=2C this will be a little long=2C but I will expand a little more on what I wrote on the subject while I was at OSH. Brian covered a lot in his recent message. Overall=2C I thought the article was good in that it painted Arion as a progressive or proactive company that is willing to change the product to make it better for the customers. However=2C please note that Nick did not change the trim system because of the draft flight review that the author wrote after flying the first demo Lightning and Linda's aircraft. The new trim system was already on Nick's list of changes to make=2C but perhaps th e timing of the trim change was accelerated because of the upcoming article . Once the new demo had the new trim system=2C the author liked the way th e new 2008 demo flew. Of course "better" is a relative term. I liked the light stick forces and stick force per G that the prototype and original de mo had (and Linda's airplane). However=2C on long cross country flights it can be more work if you have to hand fly it all the time. As to the neutral pitch stability issue=2C it was the bungee trim syste m that makes the airplane fly like it has those characteristics. Let me ex plain: First neutral pitch stability is a great situation for a fighter or an aerobatic aircraft (most of my flying time is in these type aircraft) b ecause both of them are often rapidly going from high speed to low speed an d then back to high speed again=2C many times during a dog fight or aerobat ic sequence. If you had to constantly re-trim the aircraft with each speed change you would wear out the trim button. Just kidding=2C but your work load would be high as you trimmed the aircraft to keep stick forces low. S o they are designed to always keep low stick forces=2C but in doing so=2C i t becomes a bit touchy (very light pitch forces) if you are not used to fly ing that type of aircraft. If you current Lightning or Esqual pilots with the bungee trim system want to test this out=2C pay attention to which way you really have to trim your aircraft as you change speeds. A normal aircr aft will need more nose up trim as you slow down and more down trim as you speed up. The bungee system actually requires very little trim as you chan ge speeds and=2C depending on how you have them adjusted=2C can actually re quire the reverse of this. Meaning as you slow down you will need nose dow n=2C not nose up. Weird but true. Why=2C because the bungee that attaches directly to the up elevator push / pull tube becomes more effective as you slow and there is not as much airflow over the elevator holding it in posi tion. Therefore=2C as you slow=2C the bungee is able to pull more and more up elevator. Makes the airplane act like it has an aft CG. (Note=2C this is only with flaps up. With flaps down=2C you are now flying a new wing an d the bungees generally will not completely trim off all forces.) So the n egative pitch stability that the author mentioned comes from the fact that when the aircraft (with the bungee system) is slow and you pull back on the stick and then let go=2C it will not recover to the previously trimmed fli ght condition=2C it will continue to pitch up by itself because the bungee can pull more and more up by itself as there is less airflow over the eleva tor to keep it in trim. Try as hard as I did to diagram the system to the author and draw pitch stability curves=2C he was convinced that it was a CG problem even though the three Lightnings he flew were all at about the sam e CG. His comment was that we must have weighed the aircraft wrong or miss -calculated the Cg. When you do the pitch up maneuver (pull pack on the stick and let go) w ith the new trim system the airplane will return to the previously trimmed flight condition (airspeed) thus showing good pitch stability. So=2C the o ne thing that I do not agree with is the author's thought that the "better flying qualities" of the new demo has to do with moving the CG more forward . To reiterate=2C the change to the new electric trim system is what made the change=2C because the three airplanes he flew had the same CG (within a hair of the same - certainly not enough to make a major change like he rep orted) when he flew them. I kind of hate to disagree with him because after many emails=2C many p hone calls=2C and flying with him in Linda's airplane=2C he has become a fr iend (even though he is an ex Navy "heavy" driver). He does however=2C hav e some knowledge in his Navy "Noggin". Heck=2C world record holder Earl (a lso ex Navy) knows him=2C so that in itself is a positive thing. Overall a great guy to talk to and share war stories and hangar talk with. So my b ottom line is that it is a good article=2C but I do hope readers will read the entire article and not just the first part. As to Nick flying in the r ight seat=2C all good fighter pilots want the stick in the right hand and t he throttle in the left hand. Blue Skies=2C Buz Looking for a car that's sporty=2C fun and fits in your budget? Read review s on AOL Autos. _________________________________________________________________ Reveal your inner athlete and share it with friends on Windows Live. http://revealyourinnerathlete.windowslive.com?locale=en-us&ocid=TXT_TAG LM_WLYIA_whichathlete_us


    Message 4


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    Time: 05:09:34 PM PST US
    From: "Tex Mantell" <wb2ssj@earthlink.net>
    Subject: Buz and Brian
    Thanks for your input. It has "inlightinged" me on the subject. Hope everyone has got back from Osh OK and back to building. My paint cup runth over. Slow but sure progress . I have a new name for my plane. I will call it " Juristic park" after the movie. I have encapsulated every spices of bug, spider, and others in the clear coat. Have your plane painted somewhere that has a proper booth. The tent don't work. Tex


    Message 5


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    Time: 07:03:25 PM PST US
    From: N1BZRich@aol.com
    Subject: Re: Buz and Brian
    In a message dated 8/6/2008 8:09:56 P.M. Eastern Daylight Time, wb2ssj@earthlink.net writes: will call it " Juristic park" How about Jabirusic Park? Did you paint at night? Maybe the bugs will give you the "golf ball" dimple effect and make your Lightning fly farther and faster, right down the center of the fairway (make that runway). Buz **************Looking for a car that's sporty, fun and fits in your budget? Read reviews on AOL Autos. (http://autos.aol.com/cars-BMW-128-2008/expert-review?ncid=aolaut00050000000017 )


    Message 6


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    Time: 09:16:42 PM PST US
    From: N1BZRich@aol.com
    Subject: Re: kitplanes
    In a message dated 8/6/2008 6:29:20 P.M. Eastern Daylight Time, dashvii@hotmail.com writes: In my experience the aircraft never showed even a slight negative static stability characteristic as this would be indicated if you were to pitch up and let go of the stick that the aircraft would continue to pitch up. I never saw this. Actually I have seen this at slow airspeeds in all the Lightnings and Esquals (about 7 differnet aircraft) that I have flown with the exception of the new demo with the trim tab system. As to dampening out turbulence, I doubt that there will be $0.02 difference between bungees and the new trim system. And the other pluses of the new system way outweigh that if there is a difference. My suggestion to all currently flying Lightnings and those being built is to go with the new system. You will be much happier in the long run and your maintenance headaches with the bungees (keeping them properly adjusted and replaced on a regular basis) will be gone. I know if I ever get to build a Lightning, it will have the new trim system. And with the "break even" price that they are available at, it is a great deal. If any of you have any doubts, come on out to the September 2nd annual Lightning Fly in and fly the new demo. Heck, all of you should be there whether or not you have any doubts. Buzz (ops, typo, but when I spell it with two Zs, the second Z is silent) **************Looking for a car that's sporty, fun and fits in your budget? Read reviews on AOL Autos. (http://autos.aol.com/cars-BMW-128-2008/expert-review?ncid=aolaut00050000000017 )




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