Experimentation to develop understanding of aerodynamic phenomena.

Published by: Joe Hockman on 25th Jan 2017 | View all blogs by Joe Hockman

I am going to start this blog by saying something that might ruffle a few feathers.  If you think about where we have come since Francis Rogallo days we can reflect on a rather consistent evolution and many may argue we have come a long way.  I can easily defend an argument that states we are still in the dinosaur era.  One factor at a time experimentation, tweaking and copying another manufacturers design improvements have led us to the slow evolution and state where we are today.  But if I think of where we could be today given the time span, availability of new materials, etc and using more efficient methods to extract fundamental understanding of flex wing phenomena, quantified understanding of what specific design alterations and materials yield, gee we could be light years ahead of where we are right now. Ok so I may have caught your attention. If so read on.  If not then feel free to exit now from this blog and move on.

I keep hearing this oft repeated phrase, through "trial and error" improvements are made.  That my friends is the most often used form of experimentation to discover or understand complex systems because there is very little fundamental understanding on certain attributes or phenomena. But that is the most inefficient method of developing needed understanding and design improvements.  That is why I occasionally toss in the idea of controlled experiments.  But so far no one seems to have picked up on that.

So if you don't mind I will jump on my soap box for a moment.  In my 25+ years working in R&D at DuPont and previously many years in academia I have had the wonderful opportunity of working closely with many brilliant minds.  Chemists, chemical engineers, engineers with many other specialties, etc almost all with Phd degrees and some with 2.  I taught experimental design for more than 2 decades to these highly educated colleagues.  Almost without fail, all believed the only way to develop understanding of a "black box" system is to do 1 factor at a time experimentation.  This has been drilled into their heads through course and lab work in academia at both the undergraduate and graduate level.  Then I teach them statistical methods of experimental design which can be described as objective driven experimentation within an experimental framework that manipulates multiple variables simultaneously yet is able to quantify individual variable effects and variable interaction effects in a mathematical model.  OK off soap box.

I am not suggesting that any wing designer (P&M, AC, Airborne, NW, Evolution, etc) should go out and willy nilly throw together a bunch of experiments that involve changes to many wing variables without giving very serious thought to many implications including safety, feasibility, etc. To the contrary, all aspects should be considered.  With regard to flexwing design and developing quantitative understanding we could initially take some baby steps focusing in on one variable in a way that not only enables development of a mathematical model on how that variable adjusted at various levels impacts any aerodynamic or other performance criteria that can be quantitatively measured, but also develop good estimates of uncertainty about that model. Only through careful and disciplined experimentation can true cause and effect relationships be established.

A very important word on measurement systems. Only through the use of capable measurement systems can one reliably establish true cause and effect relationships.  A capable measurement system must be both accurate and precise, otherwise either biased and/or uncertain results are obtained.  Additionally, a measurement system should be both repeatable and reproducible.  Repeatability implies replicated tests or trials will give consistent results with low error.  Reproducibility relates to different operators (in our case pilots) being able to reproduce the results of other operators. To tie this concept into recent discussion, using thick reference lines and pieces of 2x4s to give approximate guesses on amount of twist is a very crude measurement system.  It is slightly better than a WAG but it does not have the required accuracy or precision to be a useful measurement system. It is also likely not adequately repeatable or reproducible.  For this type of investigation one would want to use the best available yet practical measurement technique. Abid suggested the use of AoA sensors mounted in selected locations.  If such sensors provide accurate and precise measurements and would yield both repeatable and reproducible results then this would be by far the preferred measurement system if it is indeed relatively simple and safe to implement.  Only by using capable measurement systems can we be confident that the results and models developed truly reflect reality.  Most every one has likely heard the term "garbage in garbage out" which is extremely important any time experimentation is conducted. I am not suggesting the crude measurement Paul H used to assess twist AoA was garbage as I already indicated my view is it was better than a WAG.  In a modeling context, you can have the best most sophisticated and beautiful empirical model in the world but if all the Xs and Ys are noisy and based on questionable measurement systems then the model is likely not useful.

The experimental methods I am advocating have proven to be effective, efficient and do accelerate the discovery and developmental cycle times of any program where experimentation is needed to develop true cause and effect relationships.  I am 100% convinced that if we have specific "improvement" goals for flexwings (and for what hangs below the HB for that matter) then a simple statistically designed experimental approach will help achieve such goals quickly. Through intently observing many discussions of a technical nature on this and other forums I am amazed at what is actually "known" or "unknown" about how flexwings work or perform under certain scenarios.  I contend there is a significant in the unknown category that should actually be in the known category. I also believe that when more fundamental understanding is available to designers, instructors and advanced pilots the more we can advance the sport for the benefit of our community and make the participants and equipment safer for all.

Lastly, even though I am not a designer or manufacturer of wings, I would certainly contemplate developing the needed relationship with one (or maybe more than one) to help them pursue their innovation and improvement goals in a very efficient manner.  I have already thought about approaching Kamron at NW on this.

Feel free to add your thoughts related to both experimental methods and potential goals that specific designers or the community could pursue.

Comments

36 Comments

  • white eagle
    by white eagle 10 months ago
    Eienstien is rollin over in his black hole out their in the cosmos joe. In fact i think ive told you you even look like him?
    But for all intence purposes this is something ive been saying for years! Only you say it much better.
    But as far as R and D goes we dont have to guess . As you once told me in my quest for bird like flight. Well dave make a model.
    But the way i see it we already have the models. Crows ,ravens , hawks , eagles seagulls albatross?
    We have not even begun to come close to what has been perfectly achieved in design for millions of years. If you want a good datum point than we should start their and duplicate with the encredable advances in matierials we have today. Some developed by du pont.
    Time to get beyond t-6061 alum and dacron.
    Off course what do i know coming from the 60s i once thought if i truly believed hard enough i could just grow wings and feathers?
  • Paul Hamilton
    by Paul Hamilton 10 months ago
    Joe, I agree completly. No feathers rfled here. It is a matter of time/money and resultant benefits. My crude experiment cost me about $500 in time and money for the results I wanted. As you increase the accuracy you increase the cost. Simple math. I would love to see someone fund /sponsor such a project. Find a sponsor to fund this and we are off and running.
  • Bill Chance
    by Bill Chance 10 months ago
    Well Joe let me state I agree with you but I think you forgot your time with DuPont R&D was funded by the products of DuPont that was making money. All the work of NASA, Lockheed skunkworks, and probably your time in academia was paid for by taxpayers. As Paul alluded to and as Abid has stated many times the market isn't that big to bear the cost of much R&D. I think the Gov was studying how dragonflies flew and could change direction instantly but again that was for military uses.


    Its all $$ driven. Even major aircraft manufacturers like Beechcraft are owned by companies with other holdings. With Gibbo gone we have one wing builder in the US and a few more worldwide all trying to make a little money. We may still be in the Dino era but Larry and other builders that are passionate about what they produce have driven what we have now.
  • Joe Hockman
    by Joe Hockman 10 months ago
    Thanks for the feedback WE. Hey maybe you just have to think harder and those wings and feathers will appear.

    Paul yes all experimentation takes resources in time and money. But it also requires plenty of up front planning. Design of experiments is all about extracting the maximum information with the least expenditure of resources. I am sure that if you had been setup with AoA sensors you would have been able to easily collect at least 4 to 6 solid data points in the time it took you to get that one crude data point. If one were interested in modeling AoA at the tip as a function of bank angle, speed at entry to roll, and roll rate all at 2 levels as an example you might have been able to collect 8 data points (all combinations of those 3 factors at 2 levels). This would be enough information to develop a model to predict AoA within the factor space defined. However, those 8 conditions would ideally be replicated so that confidence levels on factor effects could be estimated. It does not require a 30 or 45 minute flight to go get one data point. In one 30 minute flight, results for 8 variable combinations could be obtained.

    Thanks for your comment Bill. No I did not forget that any experimentation requires resources. Most folks erroneously believe all DOE (Design Of Experiments) work is very complicated and costly. It does not need to be. Yes I am fully aware that more resources are justified on R&D in areas of aviation where markets are large. I do not disagree with Abid when he says that the flexwing market is rather small. Even so, there is so much inefficient experimentation that goes one with current development efforts that in about the same time and resource commitment very well planned experiments can be done that can deliver undisputable knowledge that is absent in many areas today. I am sure that almost all in the trike and flexwing industries do not use DOE because they know nothing about it and if they did understand the benefits they would. DOE can deliver competitive advantage in providing truly innovative contributions. As an example, my guess is that most flexwing manufacturers really want to be the "leader" and not the "follower" in the industry.

    Many DOE-based discoveries are also patentable. Case in point, I led all the experimental work and modeling for a new resin system to develop a new version of Kevlar (called Kevlar XP for eXtended Performance) used primarily in ballistic resistance applications. DuPont developed a new hybrid helmet for the military that was much lighter than the incumbent heavy Kevlar helmets that soldiers had to wear yet it actually improved ballistics performance. All this was done by DOE and was patented. I am sorry that I can't really talk about much of the work I was involved in but I will tell you that 1000s of DuPont patents in recent years were primarily based on DOE experimental work. Bottom line is this provides proprietary advantage and the same thing could be done in the trike and flexwing industries.
  • Paul Hamilton
    by Paul Hamilton 10 months ago
    Joe,
    Any luck finding funding for this project? Do you have a proposal put together? Please share your progress....
  • Chuck Tabbert
    by Chuck Tabbert 10 months ago
    Guys,
    I have been very active in Small Business Innovative Research Contracts over the last 30 years. I'll be happy to research agencies that might fund this research - I can think of a few - #1 National Science Foundation, #2 FAA (if they participate in SBIR), #3 NASA (have to figure out which NASA agency) & #4 DOE or DOD (have to figure out what agency to approach).
    What I would need is an abstract that defines the problem and what innovative research would solve this problem.
    These research contracts come in Phases - Phase 1 funding is about $100K and Phase II is around $750K. There is a lot of paperwork and program management required on these things.
  • Joe Hockman
    by Joe Hockman 10 months ago
    Thanks Paul and Chuck for your comments. No I have not put a proposal together but would be glad to assist with that effort. What I will do is volunteer to lead the brainstorming and strategizing on how to pursue the experimental work. As I see it the first step is to actually define some objectives or goals for the effort or project. What is it that we need to learn about flexwings or put another way, what knowledge gaps currently exist that need to be filled. When we think about potential funding sources we also need to think about primary and secondary beneficiaries of having that new knowledge. Originally I was viewing the primary and secondary beneficiaries as the trike flexwing manufacturers and pilots of those trikes, respectively. However it could be viewed more broadly.

    Often times a funding agency must see some benefit or connection with their purpose or mission. I know NSF does fund some basic research, but not too familiar with funding mechanisms through FAA, or NASA. I wonder whether NASA would see any connection with whatever goals we are trying to achieve. Perhaps if a specific objective we have has a direct connection with the safety of both pilots and non-pilots alike then FAA may to take a close look at a proposal. I am a bit skeptical about whether any thing we might envision is of interest to DOE or DOD but I may be wrong about that. Chuck I really like your ideas and please do not view my comments above as criticizing your ideas.

    One possible way to initially proceed is to actually assemble a small group of interested leaders / experts that really do want to participate in a project to brainstorm ideas and perhaps draft some objectives / goals. This could be done by a conference call or internet based video conferencing approach. Establishing some goals / objectives I think is critical as it really makes little sense to put together any kind of proposal unless it is connected to some well defined objectives. So if there really is interest in pursuing this and a "small" group of individuals want to be part of this effort, then I would be willing to try to pull together an initial meeting to kick this off. Just let me know.
  • Chuck Tabbert
    by Chuck Tabbert 10 months ago
    Joe, I agree - a GoToMeeting to discuss this would be good. I have a GoTo account and can have, I think, up to 15 folks on line screen sharing and also webcam (if we want to see each other).
    I would propose those "interested parties" send me an email and what date/times they are available (remember to say what time zone you're in). I will accumulate inputs and send out a meeting invitation with suggested agenda and discussion topics. Wouldn't expect this first meeting to go longer than one hour. Chuck Tabbert chuck_tabbert@yahoo.com
  • Paul Hamilton
    by Paul Hamilton 10 months ago
    Right now I have way to many projects I am working on but will be happy to assist.

    No sense getting together unless we have some basic goals and objectives.

    Joe, you are clearly the leader with this with all your experience and motivation as stated above. Show us some leadership and make this happen. It is your idea.

    Just start with some basic goals, benefits and objectives to get started. Who do you want to target. What do you want to do.

    What do you see to get us out of the dinosaur age?
  • Joe Hockman
    by Joe Hockman 10 months ago
    The reason for suggesting a video conference to map out some specific / goals was to get agreement / consensus on objectives that are worth pursuing. I would characterize my comment above "if we interested in modeling AoA at the tip as a function of bank angle, speed at entry to roll, and roll rate all at 2 levels as an example you might have been able to collect 8 data points" as related to an objective of gaining fundamental understanding on what influences AoA or washout at the tip the most. This is different from an objective that may be focused on a new evolutionary development in flexwings that I think may be of more interest to flex wing manufacturers. Clearly DOE can be used for any objective for which we have good control over the Xs (factors one chooses to manipulate and control) and Ys (measured responses) and for which we have a good measurement system for Xs and Ys.

    So I happened to catch Kamron Blevins yesterday for a lengthy phone call. I wanted to pick his brain on where he thinks flex wing evolution may take us in the next 3, 5 to 8 years. I gave him some background on structured experimentation and how it can be used to make discoveries and help with future design and engineering developments. I will summarize a few things in my next comments.
  • Joe Hockman
    by Joe Hockman 10 months ago
    One area both Kamron and I agreed on is that the trike pilot community is not growing at a desirable rate and there are likely quite a few reasons for this. Also fatality rates in recent years are unacceptable, but it appears the vast majority of these fatalities are with high hp trikes with small blade wings. It seems that most CFIs these days seem to prefer these trikes for several reasons but likely chief among them was the ability to fly and train most any time of day or in a wider range of conditions. But I think we both agreed that training in a slower lighter trike is probably better from a safety perspective even though it may involve more limitations on wind intensities, Xwinds, and turbulence during training. I also acknowledge that some here on TPS may not agree with the above.

    In this context, Kamron said it would be great to design and develop larger (total surface area), slower wings that provided more stability and control in turbulence than todays wings. This would provide a big benefit for training students and a better safety margin during training and for beginner / novice pilots. Makes perfect sense to me that in contrast to touching down at 50 to 55mph or higher that touching down at 30 to 35 (maybe up to 40) students have more correction time and can generally hone in more quickly on the required timing for landing and takeoff sequences.

    So again, one possible broad goal / objective is to design and develop larger wings that retain nicer handling and more controllability in turbulent conditions. Is it possible to do this? If so, what might be the characteristics or features that would enable this desirable behavior. I don't know how popular this broad goal might be among instructors and experts here but if there is interest then this could represent a broad goal for a project.

    I have developed some more extreme ideas of what could be pursued in the future that may require considerable work. One example is hybrid wings such as wings that are part fixed wing and part flex wing that impart some of the benefits of both. A possibility in that hybridization would be to have an inboard portion of the airfoil that is "fixed" or only "partially flexible" and have the outboard portion with more of the flexwing characteristics (dynamic distortion and washout and some billow) that we are familiar with so it would still be WSC but I would not rule out WSC induced controllable surfaces (eg spoilerons). Some might think this is a "pie in the sky" idea but I believe some future innovations will require some "outside the box" thinking.

    Any reactions to these ideas or perhaps other ideas for potential future innovations that may deliver very desirable flying characteristics that are not possible with todays technology are welcome.
  • Joe Hockman
    by Joe Hockman 10 months ago
    So if "designing and developing larger wings that retain nicer handling and more controllability in turbulent conditions" is a worthy goal to pursue through an experimentation project, then I would be happy to lead a small group through brainstorming ideas on ways to achieve this and to perhaps refine goals / objectives for that purpose. We could certainly initiate this with Chuck's great GoToMeeting idea. At this point I really do not know whether a project to achieve that goal is one that could attract funding from one of the organizations that Chuck mentioned. It probably depends on how the project is framed up and how well the project proposal is written. I believe that achieving such a goal does have safety implications so that aspect could appeal to an agency like the FAA. Is it possible to make some real progress toward that goal with little or no organization funding? I don't know. Maybe if it is driven by "volunteer" resources from several folks that have the flexibility and passion to push it through.

    Frankly from the out set, one of my concerns with this goal is how "controllability" or "nicer handling" is quantified. In structured experimental frameworks I have a very strong preference for well defined and quantifiably measured metrics. Subjective assessments that might be binary (eg yes, no: or good, not good) or even loose ratings (eg integer ratings on a scale from 1 to 5) can present real challenges for unambiguously measuring performance improvements. I do have some ideas on how to better quantify such characteristics and others may too.

    Lastly, this was just one idea that Kamron and I brainstormed. Others may have different goals / objectives that have merit and are worth pursuing within a project program. If so, speak up. Now is your chance to have some influence on the future evolution of trikes / flex wings.
  • Paul Hamilton
    by Paul Hamilton 10 months ago
    Joe,
    Thanks for your efforts here. Please do not get your feathers ruffled since we are just throwing out ideas and providing constructive opinions. I think we should think way further out of the box than larger/slower wings. But first I will address the larger wing concept and my experience/findings with this.

    Yes I have talked to Kameron about his thoughts about slower wings and I know how he feels. However, I do not agree that larger slower wings are the answer. Why?

    First off, I feel larger more efficient wings will not increase trike participation nor grow the sport. Larger wings, no matter how you cut it, are more susceptible to turbulence/bumps/gusts. Simple math - wing loading. The bigger the wing the more it gets thrown around. The lower end flex wing already has quite a bit of flex to absorb the bumps. I have noticed that the students/pilots that have large wings are more limited to the wind and bumps and thus do not fly as much or are scared to go. Those with smaller wings, generally a higher wing loading, are out more having fun flying rather than scared to go out in the wind and bumps.

    As far as speed for takeoff and landing, as a simple example, let’s say you have a 15 m wing, 700 pound trike that lands at 35 MPH. You put on a 17 meter wing and the stall speed only goes down to 33 MPH. Not much. Lift is a basic function of velocity squared. To try and lower the stall speed by 10 MPH, the wing would simply get to big and not be practical.

    I have found overall, that students easily get used to a little extra speed for takeoff and landings with not that much time and effort. I would estimate it takes about an extra 2-3 hours of training to train students in a faster wing. Over the training period, this is easily made up with being able to fly more in higher wind/bumpier conditions. Now they have the ability to go out and fly in stronger conditions and/or be less scared when some wind or bumps show up. This will help keep and retain students/pilots.

    As we have been over this "faster blade wings are the fault of accidents", we have seen and most agree that they needed extra training to be competent/transition. It is that simple...

    Yes, slower/larger wings do cost less with less engine power required and less fabric undersurface, but also have their disadvantages. I have nothing against slower simpler wings. They are a great fit for many.

    I feel if we are going to make an effort with any type of development, we should think way outside the box. Go well above understanding what we have but pursue developing something way better.

    What do the birds do? Variable geometry, variable camber, variable wing area, less drag, lighter weight and easily transition from flight to non flight. I feel this is what we should set as our goals.
  • Abid Farooqui
    by Abid Farooqui 10 months ago
    Joe: Just a quick comments while I caught this on TPS.
    Smaller wings do not necessarily land at 55 mph. I think Revo does but its also with BRS etc. weighs 680 to 700 pounds empty before you even step in it.
    For instance DJ-2 with Cheval 12 wing, with 2 normal sized people can touch down at 43 to 45 mph with proper technique. With a bigger wing you may be able to get down to 38 mph. Its not a huge difference and you are going to get knocked around quite a bit more.
    The accidents with small wings are not happening in the UK. You have to wonder why is that if this logic is to be applied. Its not the landing phase either where but the actual flight maneuvering phase where serious accidents are happening. I personally think the training is passed on a bit too quick. Now if the goal is to solo someone faster in very calm conditions than a bigger wing may indeed work.

    The best would be to develop a wing that changes size and shape both for circuit profile for shorter takeoff and slower easier approach to landing and then goes smaller for cruise and for flying through bumps. That however, demands a market much bigger than what we have to develop. Though I did hear that Air Creation got an extension to their 200 trike sale contract to Egyptian special forces and now they want another 300 trikes from them. So may be AC can do it.
  • Larry  Mednick
    by Larry Mednick 10 months ago
    Ironically we just released our new 14 meter wing which has incredible stability and all the positive things you come to expect from a 14 meter wing without feeling like you are flying a truck. It is much lighter in roll and more stabile than the Discovery 13.5. It is the next step in the direction of what you guys are talking about. We started making the wings small in order to handle turbulence, have light control forces and authoritative handling. Then we figured out how to make the handling too light on the small wings... now it was easy to make a big wing do it all.

    Come down to Florida and fly the all New RIVAL X. It's not the "fighter jet" the smaller wings are but it is light, stabile and extremely easy for anyone to fly
  • white eagle
    by white eagle 10 months ago
    Very good comments above. Gosh minimum vne for a light aircraft such as a piper sundowner is not any different than a fast trike!
    Iam someone who has been thinking outside the box for a long time . Although their are some who well think iam a little to far outside the box. Or say one who flew over the coo coos nest! But iam ok with that!
    Paul made a good point that it doesnt nessasarily have to be a big wing. (Gosh iam agreeing alot more with paul lately) must be cabin fever!
    More variable efficient wings is a good direction. I see some of this happening with variable trim , V/G tech, roll dampening.
    But more more outside the box !
    The advancement in military wings , high aspect ratio, carbon graphite stealth has all been paired with a ridged wing and higher horsepower!
    As i have suggested many times the real beauty of trike flying is the view of birdlike flight.
    As far as iam concerned back in the davinci days the birds were the masters of flight and in the space age they as far as efficiantcy still are the leaders and will hold that tital for a long long time to come.
    So how di i see that we could incorperate some of their physics into a more versital small or big wing!
    Break away from the t-6061 aluminum bar frame of a hg wing and reasearch a carbon graphite frame that has more phyisiology structure of the bones of a birds wing . That could exspand and contract aspect ratio!
    Small diameter tubes of carbon graphite that are bound by elastic can be very very light and incredably stong and resist breakage when severaly deformed by excessive g loading .disapating the tourqe energy.
    It has also been proven that the surface design imprinted on wing can greatly increase the molecular air seperation ,increasing lift coefficients by a large percentage. Those little lines going right and left from the shaft of a birds feather , the ones going outbard direct the molecular airflow on the top surface outboard. And the lines tucked underserface of the inboard feather direct molecular airflow inboard undersurface towrd the root . So much more than just burnuleys princaple. Something iam very supprised has not been incorperated into military technology even yet.
    Trailing edge line could be incorperated with flat carbon exspandable batton like inserts that could exspand and contract somewhat like varible geometry to resemble the action of the primary feathers of a bird.
    Most people do not know that their is a laminar seperation of each primary feather in bird flight.although very small the one primary feather has a small gap overiding the next primary feather. This also greatly increases the lift coefficiant and greatly reduces the parasidic drag.
    Although some of this may not yet be practicle in application, i think we should be at least looking at it!
    I truly believe that with modern lazer printers. The ability to mass produce carbon graphite. And many other materials such as graphene that joe hockman has a much more exstensive kowelege of working for dupont that we do! We already posess the technology to advance trike and hang gliding wings incromentally toward are more technologhical adavanced feathered friends.
    Of course the bottom denominater is like everything else what really causes a wing to fly. The reply is. MONEY! Unless you are like me that has a brain of a mustard seed.
    One must truly hope that i dont win the clearing house sweepstakes .I must say thou it would be so cool to hang out with larry mednick,kameron,and ,abid,and paul hamiliton with some little tiny wings underneath a huge tree and say hey lets fly straight up and land on the tallest branch!!!
    I already hang out with joe and at least when were listning to pink floyd we can land on that branch?
  • Joe Hockman
    by Joe Hockman 9 months ago
    Thanks for the continued comments Paul, Abid, Larry, and WE. Paul, rest assured you did not ruffle my feathers. I think I understand your comments and why you do not believe evolving larger wings is that useful. Just to be clear, the suggestion to work on larger wings that offer more controllability and better handling in turbulence was not in my mind an "out of the box" idea. But I do like it. In a sense one could argue that Mark Gibson provided a solution for that with the 17M RST since most any wing with RST (reduced span technology) is less affected by turbulence than a wing with similar squares with a broader span. But I would contend that the RST Gibbo wings sacrifice on efficiency so from my perspective the RST approach is does not offer the compromise I am interested in.

    Abid, I really do hope I will have a chance to fly the DJ II with the Cheval 12 but my guess is I would be more interested in the Cheval 14. I like your idea of wings that can change size and shape which would be a significant step change. Paul also mentioned variable wing area, variable camber, and variable geometry. These are all great ideas and we have already seen a number of ways to change VG.

    Larry, I did not realize that your new wing, RIVAL X, was 14M. That is fantastic. If you have been able to retain the nice handling, stability, and light roll pressures then you likely have a winner. Some day I hope I will have an opportunity to experience the RIVAL X. I think with the variable roll damping system you have, this could actually be a very useful solution on larger wings to provide nicer handling and control in turbulence.

    WE, yes you have been thinking out side the box for some time. Could it be that you flew over the coo coos nest a few decades ago? But you are right, that is OK. We do need outside the box thinking for making real improvements in wings for the future. I will admit that I seem to have some mental barriers in visualizing bird like wings, feathers and all that could be designed and engineered for trikes.

    So where to we go from here. If variable wing area and variable shape and maybe even variable camber represent a desirable future state for trike wings, then how do we get there?? As mentioned earlier, we already have several different implementations of variable geometry. I think at least a couple of those VG implementations do make a very slight change in variable camber since with VG full on, the airfoil is flattened slightly. But clearly larger dynamic changes in camber, and changes in wing size and wing shape would have a much more dramatic impact on what could be accomplished in different stages of flight. It seems to me that the levels of complexity that will likely be required to achieve such goals would require at least one highly accomplished wing designer to be part of the project team. It is not clear to me that any of the folks that have spoken up on this thread fit that description or am I wrong about that? I think that WE is right, that changes to wing shape and size in flight will likely require use of advanced materials (eg CF, resins, Kevlar, ?) and that too would require some expertise with such advanced materials. Do we have that expertise here? I also suspect that with some of the complexity required to achieve these goals will translate into considerable costs for such wings. Would there be any market for such wings? Maybe very limited at best. Is this some thing we should pursue and put together a proposal for funding?
  • white eagle
    by white eagle 9 months ago
    Very interesting and well thought out read joe. Because our brains are hard wired mechanicly over the last few centurys it makes it more difficult for us to leap out of a box and off a mountain.
    I think iam a genetic throw back? First i dream very vividly of every aspect of flight like a bird. Sometimes its so real that i have to question reality upon waking. How much did the ability to imagine and its effects have on a evolutionary scale.
    What made some small dinosaur believe he could reach that flying bug faster if he spread his arms and folds of skin and then feathers developed?
    To me the most perfect course in engineering is to imulate as close to nature as possible. The quick fix to a million years of evolutionary dreaming!
    In physics rules must be universal . They dont change. I look at a birds wing . No wires, no king post. Muscle on the wing structure ,not much meat eating chicken wings if you ask me. Speed range of a birds wing is incredable! Lift coeficiants, incredable. Landing speeds incredable.Ability to repair incredable. No repairmans certificate needed.
    Ok let me help you into my box which really is the dreamscape universe we enter when we sleep. Wrap your head around imagination of evolving a wing like a bird but developed with modern egineered matierals.
    Start with the exact bone structure of a bird but bones are made from bound in elastic tubes of carbon graphite atached to carbon graphite joints. Then meat and muscle. Controlling chords to exspand the frame and maybe small robotic motors. Some form of latex light foam rubber to help form the airfoil datum. So what you have is a wing that resembles what you see after you plucked a chicken wing . A much longer and larger scale.
    For now iam going to leave flapping out of the picture. So some rigidity restrictors to help the wing structure maintain a somewhat soaring platform with diferent available flight settings.
    Skin that whole wing structure is skinned in some form of streachable elastic that can exspand and contract with the wing. Real down feathers can be sown into that structure as the have a role to play in the airfoils efficiatcy regulating airflow seperation. Then primary feathers can be duplicated by flat sheets of carbon graphite with the same pattern of lines regulating molecular airflow seperation. Shafts are attached by two halves of tapered graphite tubes being glued 1 top 1 bottom forming a feather shaft.
    Shafts are sown into a matrix of elastic fabric with a tendon like chords atached to a robotic motor and controller. So that each carbon feather tucks in when drawn in underneath the other. When exspanded carbon feather battons exspand to the point that the only the inboard lining of the carbon feather is underneath the lining of the next inboard carbon feather!
    A tail would be built in a similar way modeled after a birds tail.
    The tail of a bird is so much more efficient by far than anything used in aviation.
    Greatly increases aera.efficiatly manages drag. Acts as a hugh flap in landing. Folds in for increase speed in flight. Acts like electric trim.
    This may all seem far fetched but change starts with one idea at a time. Untill someone percieves and acomplishes something derastic!
    If you dont have someone on your engineering team that thinks a good deal outside the box ! Than all you really have is a BOX?
    But thank goodness most trike pilots, hang glider pilots at some point when they were younger imaginativly decided the could jump off the roof of their house with that box.

    Everyone please please ruffle my feathers. It means that i have them.
    I like dreams the dont cost me alot of money!
  • Paul Dewhurst
    by Paul Dewhurst 9 months ago
    I think if we are going to grow ( or stem the retraction) the global trike market we need to ring fence some important aspects to 'keep our feet on the ground':

    1.Keep costs under control and strive to keep things simple. Fancy materials only if they save money or increase value enough in other ways.

    2.Make the machines easier to own. - Quick wingfold that can be done in under ten minutes would be a big boon for most of the world where hangarage is either not available or very expensive.

    Reducing HP needed so simpler, lighter and cheaper alternative engines could be used.

    Increasing ease of flight in turbulence - without high takeoff and landing speeds and big smooth airfields needed. The big draw of gyros are the stability in turbulence - and they land short - but almost everything else is worse.

    Increasing stability on the ground and resistance to roll over.

    Make sure they look cool and desireable..
  • Paul Dewhurst
    by Paul Dewhurst 9 months ago
    Joe - re the comment about quantifiable characteristics. - defining handling qualities has always been an issue in test flying feedback. A tool developed for this is the Cooper - Harper rating. Worth a google.
  • white eagle
    by white eagle 9 months ago
    Paul Dewhurst i really dont see were the cost has been prohibitive. Maybe with the high end trikes for folks like me.But scanning through barnstormers a wannabe pilot has so many options that i think just about anyone who wants to fly could in some fashion. The real reason i think were in decline is lack of ambition. During the late 60s 70s and 80s people were more inclined to adventurous out door activity's. Now days i think people our more pacified with phones virtual reality.
    Iam not totally disagreeing with your post . safety is an issue and i would love to see a smaller more affordable 4 stroke solution to replace the 503 and 582.
    you may think my post our a bit eccentric . Well yes but i would be delighted to be flying over any nest even a coo coos nest. I guess what iam suggesting is that the same thing i saw in working in the hang glider and ultralight industry in the 80s, Was that ultralight manufacturing ends up moving in the direction of trying to producing an airplane. And that is a well worn out competitive field. Gyros do well because they have their own little niche. I agree with you totally that concentrating on safety , stability, resistance to roll over ,stability in turbulence is a good direction of concentration. But we must not forget the roots of our bird like flight. I have flown lots of airplanes but to me real flying is a hang glider or a good trike. theirs just no comparison.
  • Larry  Mednick
    by Larry Mednick 9 months ago
    There is something to be said about SIMPLE. Flex-wings do not need to be complex to work well and fly well in turbulence.

    Our New REVOLT trike we are unveiling at SNF April 5th will work awesome with its standard 582 engine. The one we are bringing to the show will have 100 HP and the new 14m RIVAL X. The RIVAL X is as stabile as our 11m with super soft, light controls. We are using this on pretty much all New REVOs now as our Flagship wing.

    Oh yeah, and 22" STOL tires to land anywhere!
  • Paul Hamilton
    by Paul Hamilton 9 months ago
    Yes Larry simple is always better. Have been waiting for your announcement. Hopefully I will be one of the first to get one.
  • Paul Hamilton
    by Paul Hamilton 9 months ago
    OK Joe and all,
    Long ago and far away I have three specific projects I worked on to improve the performance of flex wings. Each will have a different blog because they are completely different approaches. First is the variable camber wing/airfoil as you will see from the new blog featuring the Razr wing...
  • white eagle
    by white eagle 9 months ago
    Pretty cool paul good days indeed. Were a long way away from deflexor tubes
  • Job Chithalan
    by Job Chithalan 9 months ago
    Larry, the name REVOLT is cool. Goes well with the rest of the range.
    Now how about a sneak preview for your mates, here at TPS ?
  • white eagle
    by white eagle 9 months ago
    Well heres a link of an old friend of mine gerry breen who also flew over the coo coos nest and basicly has demonstrated exactly what i have had in my mind for 40 years ? https://youtu.be/fJMsf9ahJRE. a must see for everyone interested in flying over a coo coos nest? This is out of the box triking 2030
  • Job Chithalan
    by Job Chithalan 9 months ago
    I knew Gerry Breen when he was operating from Crickhowell in South Wales
    Very daring but not much of an engineer. He built a soarmaster type power unit. Did not check clearances. His toe got chopped off by the prop. Ouch!
  • wexford air
    by wexford air 9 months ago
    got my license with Gerry! what a guy. He could make that quantum speak to him
  • white eagle
    by white eagle 9 months ago
    Job and wexford. I cant remeber if it was one of you who got me in touch with gerry who now lives in portugal. But we had a very nice conversation about the good ol days at american aircraft.remembering all the just great folks. Hell gerry practicly paid all my paychecks. He was i think one of our biggest importers of the eagle xl at breen microlights in england.
    He may have not been the best engineer but he sure did alot to promote the sport in england.
    I dont know how much gerry is involved with the birdlike wing that he introduces with roger dodd but i thought it was a great example for this blogg .
    I cant wait till theirs more information on the conclusion of this craft. I use to sit with bryan allen and discuss this very process in the 80s.bryan would of flown over the coo coos nest with me.
    Like paul hamiltons razor design. Back in the early eighties the inovation and inthusiasm was just phenominal. Their was a hugh fly over the coo coos nest mentality. I truly miss the spirit of it all . Anyone who was lucky enough to participate in any form of those days are blessed.
    Are aerodynamical engineer romel who was a good friend designing things for larry newman. I remember him at a party at my house telling me how he excaped east germany over the berlin wall. Took a sailplane up into a cloud flew into west germany put it in a dive and tore the wings off and bailed out .he came up with some pretty interesting concepts in wing design.
  • wexford air
    by wexford air 9 months ago
    Hey Whitey. I think that was me that put you in touch with Gerry. Hope he's not too much of an old fart just yet! I think theres a book in you yet!
  • wexford air
    by wexford air 9 months ago
    whats the coo coos nest>? jack nickolas cuckoos perhaps??? if so then Gerry flew over that one a long time ago, ha ha
  • white eagle
    by white eagle 9 months ago
    Thanks again wexsford. Yup gerry was his ol self. Told me he was retired but still flys and invol ed. Me and my hang gliding partner back then were and still are pretty competitive .We used to take majic markers and draw all these hang gliders all over gerrys shipping crates before they were shipped overseas. Larry newman was just furious with us . My buddy didnt like larry to much and decided to quit but before he did he shipped like 8 wrong sail color eagle xls to gerry. That was like 3 large crates for each eagle. Hugh mistake. Gerry just graciously accepted them whew.
    Yes wexford that the right coo coos nest alright i think every pilot has to fly over it at least once. I use this term for when the most unexspecting wierd problem presents itself while flying.
    Example. Flying at elk river i was trying to show my safety airmanship by doing an empressive walk around flying my soaring trike. But when i took off and got about 500 ft my hall windmeter cap came off and the large wire and float as i would add throttle would come up almost out of the tube. It was mounted on my compression strut so i couldnt unbuckel and reach it. I didnt want to have it go through my prop with not very good emergency lzs their. If i let off the throttle to decend it would float up and if i would add throttle to climb it would float up. So not trying to create a noticable situation i had to main just enough airspeed to keep the wire dangling in the tube and try to land on the narrow run way. But to say the least for a little bit i was flying over the coo coos nest . It just had to happen to me
  • Paul Hamilton
    by Paul Hamilton 9 months ago
    Hay Joe what is the plan?
  • Joe Hockman
    by Joe Hockman 9 months ago
    Paul, I did not define a plan. It seems to me that there were a variety of opinions expressed on this thread and most certainly had some merit. Although I personally like the idea of exploring more advanced wing design options that could include variable wing area and variable shape, it seems to me that this would be added complexity and potentially considerable cost which are 2 key considerations that Paul D brought up. Also who would be the customers or is there even a market large enough to justify significant resources. I did review your Razr wing information and although I found it interesting, I also felt that although this approach to variable camber might work for a simple HG wing just to explore AoA dependent wind-driven inflated camber changes but I have my doubts that this would be a useful approach for a trike wing with heavier wing loading. Not sure but there may be some innovative ways to force camber changes using different materials. My personal feeling is that there may be a bigger bang for the buck through changes to in wing area and shape although I suspect this involves non-trivial complexity. Of course we have already seen a number of approaches to variable geometry and I think that is the case because it is inherently easier to modify wing geometry in flight that wing shape and area.

    If you go back and reread my introduction to this blog and early comments you will notice that my main thrust was to promote sound use of experimental strategies to understand aerodynamic phenomena or to conduct R&D for new wing innovations. I was not proposing that we start a project for the sake of having a project. I did however on several occasions volunteer to provide my expertise in experimental strategy, statistics, and mathematical modeling IF there was an interest to investigate some aerodynamic phenomena or IF there was an interest in a development project. You may recall this blog was motivated by your earlier video where you used a 2x4 block to estimate AoA changes at the tip (increase in washout) on the Rival S in a quick steep banked turn.

    Did you have a specific plan or project that you wanted to pursue?
  • Joe Hockman
    by Joe Hockman 9 months ago
    WE, I forgot to comment on your video of that bird like contraption that Jerry Breen was pursuing. I found the video very interesting but I really want to see future developments with actual flight tests.
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