RE: help with non-planing shapes
I shot an arrow in the air -
Posted on: 11/19/2009 8:13 AM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9264747

RE: My new and improved wing is RTF (Take 3)
Theonly thing I haveever found for a built up structure like this is really pretty simle You add diagonal ribs -very thin/light-then capstrip with 1/64" thk plywood here is a pic of an aileron I did to correct early design by H9 onthe EXTRA On my Bucker Jungmans - Icap stripped th sheeted wing panels for same effect - the W configuration is the most desireable
Posted on: 11/18/2009 11:57 AM by Author "dick Hanson" in the forum "Extreme Speed Prop Planes"
http://www.rcuniverse.com/forum/fb.asp?m=9262760

RE: How important is dihedral for a Low Wing?
If the info was in RCM- it must be right. The only thing that rag was good for was cover pics of the neighbors well endowed teenage girls stnding around the swimming pool. That ain't all bad. Beats listening to the wife snore.
Posted on: 11/17/2009 10:59 AM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9260059

RE: How important is dihedral for a Low Wing?
[quote]ORIGINAL: HighPlains What I want to know is how many wings has Dick cut in half to correct the dihedral over the years? Or do you just build another and make the twick then? Myself, I discovered this phenomena about 30 years ago when I built a low wing stik for a wing that I had hanging around after a little stik was destroyed in a crash. The wing was originally for an Ace Super Pacer (low
Posted on: 11/17/2009 10:55 AM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9260050

RE: How important is dihedral for a Low Wing?
The pattern planes -years back -had a maneuver called the slow roll - at the time , the slow roll was actually -a slow roll and the good ones would go from horizon to horizon -on line-with no altitude or course variation. I setup my Tipos such thae they had a little adverse roll- Why? The maneuver started with say a RIGHT hand aileron input- this then got some gradual LEFT rudder input -to set up a bit of nose high AOA As the model reached knife edge, the rudder input was gradually reduced then as inverted flight occurred, all rudder was out. now the last half of the roll started - RIGHT rudder was gradually applied and here is why the adverse roll was built in. The model was slowing slightly throughout the roll and adding rudder -if or neutral would speed up the roll rate So- by having slightly adverse roll, the rudder input could be increased without speeding up the roll rate If you actually have flown this extended maneuver - a number of times-you know what I mean. Its is far easier to keep the roll rate constant if you can increase rudder input, without increasing roll rate The net effect is a visibly even roll rate
Posted on: 11/17/2009 10:35 AM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9260009

RE: How important is dihedral for a Low Wing?
For the perfectionists
Posted on: 11/17/2009 8:31 AM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9259801

RE: How important is dihedral for a Low Wing?
On THAT one a little dihedral makes it more user friendly How much? I don't know - some - I have this saw-
Posted on: 11/16/2009 10:21 PM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9259154

RE: How important is dihedral for a Low Wing?
If you feel like learning more about dihedral- try this -as another experiment. buil a low wing plane with an aspect ratio of under 3-1-with no effective dihedral the make another wing which will fit the fuselage with an aspect ratio of 7-1 keep wing areas about the same Finally make a wing with an aspect ratio of 1-1 You will find that the need for dihedral decreases as the aspect ratio decreases - Long ago - I built a Jensen Ugly Stick for Dave Brown- a rush job - I started the kit at 8:00 in th morning and gave him the plane in that afternoon about 3:00. Those were beautiful kits -everything fit. I can't recall if that kit had dihedral -Ithink it did that was in about 1975 We had a Fun Fly the next day and I had a 15 size World Engines Expert stick -built upside down with dihedral Dave had the Ugly Stick- We were 1&2 in all the events. I won all the events expect the spin down -which was counted in number of turns - so Dave won the event Grrr The Stick design (Phil Kraft gets credit) is still an excellent model -there have been at least 100 versions of it -some good some awful. The one shown in the photo is good one.
Posted on: 11/16/2009 5:10 PM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9258375

RE: How important is dihedral for a Low Wing?
If it were easy to do a little dihedral would help on THIS setup The rub is - the strength of the wing root is compromised As for stability - really not an issue. OnTHIS setup The big change is that the relationship of th vertical area including the fin n rudder - is changed quite a bit The application of rudder will cause roll in the opposite direction and simply turning with a banked wing (not always re'q'd) -WILL be a little different Go ahead and do it - . See what you can learn PS- some of my extremely aerobatic stuff has dihedral CAPS/EXTRAS/ZLINS-all have dihedral and setup right, are very neutral .
Posted on: 11/16/2009 9:10 AM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9257330

RE: New build
Having been through all of this many times - some more food for thought The landing gear You simply can NOT beat wire for strength to weight and shock absorbing fibreglass is the worst. carbon fibre is light but lousy on shock absorbing Foam wing - don't try i unless you have done a bunch of em - for this type plane, the open structure is easily best weight to strength Ihave personally done a least 1000 foam wings -of all types (I built n sold custom stuff fo almost 30 years.) For power - the setup on the Seniorita shown is a .20 K&B with stock muffler as quiet as most electrics - That model is 4 pounds flying weight and all kit wood was used. A really nice easy flyer and will loop at full speed in level flight (just barely) The airframe -without any hardware -but completed was - 3 lbs. You can easily do the plane you wnt at 4 lbs then add hardware You can NOT add expensive lighter components to make a lighe model Many try it and just blow a lot of money for very little return. You start with a set of scales and a plan for the finished weight - Hope, just won't do the job. The Cap in the picture is 13+pounds and 1100 squares with a 40ccengine and a carbon fibre tuned exhaust-and 7075T6 cystom made gear - it has solid foam panes on all surfaces and an all balsa fuselage it LIGHT by any standards. That construction was done for again-best strength to weight - The model is an all out 3D /pattern setup I mention this to show the different approach-for different tasks
Posted on: 11/13/2009 11:00 AM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9250830

RE: Penetration
Not to blow a hole in all the nice math How much actual flying have you done with small light models To put a fine point on it -here is what really happens- the lighter model is stil lthe best Why? because you can more easily accelerate it and retain positioning . I went thru all this on pattern models many years back- the light stuff wit throttle control again the best the sensitivity /uncontrollability -I just can't buy- done too much flying of these types -If the power is correct you simply add power when needed to overcome a upset IF-you are trying to fly a 20 mph plane in a 20 mph gusty winds - you are sunk -for openers -Nothing works Heavy models suck- unless you are flying slope and using wind/gravity for power.
Posted on: 11/4/2009 2:00 PM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9227861

RE: Penetration
penetrating a myth is quite a task- The old answers about "how airfoils lift and how one airfoil is a higher lift type than another persist -as does the business about how a particular airfoil penetrates better etc., etc.. ANY flight requires the ability to confront (or use) gravity weight/aerodynamics and or speed, EACH are involved There is no single factor which improves penetration. So far -for me- the lightest model with the most power wins on all fronts.
Posted on: 11/3/2009 5:41 PM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9225847

RE: optional fuel pulse port on walbro
I had a real education on this Walbro- -they did not drill the passage -shown by the drill- the engine would start n run but would not feed fuel past an idle. Some models Walbro use same basic bodies -then have various covers Big surprise.
Posted on: 11/2/2009 10:27 AM by Author "dick Hanson" in the forum "Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9222276

RE: Stab twist: one side. Effect?
Here is another trim which is fun to play with IF on puts a small plate at the top TE of the rudder What is the effect on pitch?
Posted on: 10/31/2009 11:01 PM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9218908

RE: Stab twist: one side. Effect?
Taint the roll the BIG problem is just like a car with a low back tire the side of the stab with hte most drag ,will try to center its self on the line o flight to restate the center of the drag at the rear will try to center itself. It act's like rudder trim
Posted on: 10/31/2009 7:24 PM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9218430

RE: Stab twist: one side. Effect?
I have fixed warped wings, stabs of various types -including those like yours Pattern planes at one time were glassed and painted and this same situation occasionally arose. The trick is to determine which way the twiat must be made-then - on the bottom surface, make a diagonal slit thru the covering from LE to hinge line this MUST be done such that the twist will close the slit when pressure is applied. Block the stab into position after feeding in slow thin drying epoxy along the entre slit- then wiping excess awy with a damp rag -or with de natured alcohol The result will be a a hairline crack on the surface if you were careful.
Posted on: 10/31/2009 10:48 AM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9217389

RE: can you compensate for weight?
For those who may care The elevator throw can be as high as you uwant to make it There is no magic setting to avoid unwanted responses How can that be? Yoiu just have to match throw with speed the faster the model is travelling - the less any high throw can be tolerated also the lighter the model - the more the elevator can be deflected correct elevator throw is like "the best airfoil" there ain't one answer. Same goes for a 40 lb 42% or a 5 ounce indoor setup
Posted on: 10/30/2009 4:07 PM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9215589

RE: Golf ball dimples
WoW I simply noted that lift and drag are really in the eye of the beholder You say banana I say bahnahna Lift and drag are like Yin and Yang But The proper use of aerodynamic terms is nice - if gives people something to nit pick. Like the blind men examining an elephant.
Posted on: 10/30/2009 9:15 AM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9214673

RE: NEW DLE30!
Any engine which puddles is simply a design problem that should have been causght with even the most elementary new engine tests. Period. The cause of puddling is well known the remedy is usually simple - Mount engine at an angle I ran into this problem on a poorly conceived ZDZ40 design a few years back. A well known 50 also did some minor puddling - The rush to cheaper and cheaper engines has shown that there is a market for anything which even remotely resembles an engine You think you can get a Honda from a Pinto / Vega/ K car mfgr?
Posted on: 10/30/2009 9:03 AM by Author "dick Hanson" in the forum "Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9214654

RE: Golf ball dimples
Goodness -you are going to upset the aeronautical terminology correctness control gruppe. Lift is drag and drag is lift- is my take on it But you must use the proper words . These guys tend to get upset easily
Posted on: 10/29/2009 8:47 AM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9211834

RE: Walbro, tillotson....universal problem?
It is possible to do a pretty darn good closed loop setup for SOME uses My favorite is a tuned exhaust (for quiet operation and increasesd power) add to this SOME type of balance correction using the exhaust pressure which increases fuel flow as the exhaust goes resonant. "HUH?" I have measured this many times and in all cases , I found that as the power increases the need for fuel increases sharply. Note I did not say as rpm increases tho typically the rpm does increase. Where many modelers lose it -is by leaning out the mix till rpm is maxed in level or slightly diving flight The engine may make more rpm -but the load is lower as soon as the load is increased . the engine goes lean. This situation is common as fleas on a hound. The so called pressure regs sold by sme outlets are yet another botch up I measured the pump to pressure readings on all the early OS pumps Perry etc., and always got the same result max pressure at lowest rpm. Worthless The fuel DEMAND relative to power goes up very sharply On Walbro setups - the easy fix is to insure that the reg diaphragm does not see a decrease in vent pressure as the engine goes to full power Also the tank should flow as easily under high demand as under low demand I believe in a forward facing vent line and no filters in the lines.
Posted on: 10/28/2009 1:55 PM by Author "dick Hanson" in the forum "Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9209468

RE: question about airfoil
Sor our purposes -I can't see how a semi sym foil has any advantage over a fully sym shape airfoils CAN NOT add lift Except at a particular speed - where they can operate more usefully The good ol flat bottomed things were easier tobuild on a bench -so that was an advantage All of the numbered wind tunnel shapes were derived from testing at a given set of parameters once you change any one of em -the superiority of the shape is gone. So an airfoil with more lift is -? high lift at high speed? high lift at low speed Ihear about high lift airfoils all the time on here - so far I have not seen what constitutes a high lift shape. The best I can come up with is : a shape which works over a wider speed range However the lift is not increased over that entire range It is simply a compromise.
Posted on: 10/28/2009 1:36 PM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9209422

RE: Walbro, tillotson....universal problem?
"referrence pressure" is not in many users vocabulary. Nor is "vacuum signal" The fixes suggested for getting the pressure constant (across the topside of the regulator diaphragm) are endless and many are worthless. The carbs on glo engines also suffer from air pressure problems . The use of exhaust pressure to the tank can fix most of these. Glo engines because of the fuel used ,typically can tolerate much more varience in fuel to air ratios. My ZDZs and Evolutions etc., don't have fuel mix problems as noted -because I always center the tanks on the carb . This keeps the fuel head at a more constant level Also my cowlings are always setup to provide maximum air extraction at the rear or bottom of the cowl. this helps stabilize interior pressures and keeps the engines cool to boot. For what it's worth , a large plenum attached to the top side of a Walbro type carb, will stabilize any pressure problem. a balloon on a piece of tubing attached to the diaphragm vent can do this. OR a line from the vent to a box at the carb inlet, etc., can also work
Posted on: 10/28/2009 8:55 AM by Author "dick Hanson" in the forum "Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9208744

RE: Elevator SNAPROLL
[quote]ORIGINAL: onewasp [quote]ORIGINAL: RCHUGHES [quote]ORIGINAL: onewasp So long as we have Bruce's attention......... Would you please comment on ''flight'' (I use the word loosely) on any plane with the CG located behind (that doesn't mean .001'') the neutral point ! My remarks on this are included in post #15.............and I'm still impressed !!!!!!!! [/quote] you can get back up all you want but I know other people on this forum that can Back up my comments, A plane can fly with a CG past the Neutral point I have done it, I know other people that have done it, with the right Airframe it actually does not fly bad at all, does it really matter to you that much?? [/quote] Relationship to aircraft and missile stability and control * If the center of gravity (CG) of an aircraft is forward of the neutral point, or the CG of a missile is forward of the center of pressure, the vehicle will respond to a disturbance by producing an aerodynamic moment that returns the angle of attack of the vehicle towards the angle that existed prior to the disturbance. * If the CG of an aircraft is behind the neutral point, or the CG of a missile is behind the center of pressure, the vehicle will respond to a disturbance by producing an aerodynamic moment that continues to drive the angle of attack of the vehicle further away from the starting position. The first condition above is positive static stability. In missile analysis this is described as positive static margin. (In aircraft analysis it may be described as negative static margin.) The second condition above is negative static stability. In missile analysis this is defined as negative static margin. (In aircraft analysis it may be described as positive static margin.) [b]Depending on the static margin, humans may not be able to use control inputs to the elevators to control the pitch of the vehicle. Typically, computer based autopilots are required to control the vehicle when it has negative static stability - usually described as negative static margin.[/b] [/quote] Reminds me of the tongue in cheek def. of understeer and oversteer. "If you go thru the fence nose first, the car has understeer- etc.." My old Chev powered Healey, had definate oversteer (CG was 45/55, front to rear). My TR3 had -well understeer plus under power
Posted on: 10/27/2009 5:20 PM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9206873

RE: pusher vs. tractor
It's like moving 20 ft of chain down a road It is far easier to pull it than push it. Better yet - you don't look strange doing it.
Posted on: 10/27/2009 2:33 PM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9206383

RE: Golf ball dimples
[quote]ORIGINAL: banktoturn [quote]ORIGINAL: dick Hanson [quote]ORIGINAL: banktoturn Your guess as to the mechanism by which distance balls acquire lower spin rates doesn't happen to be the one that the ball manufacturers give, but it doesn't really matter. The salient observation is that balls intended to fly farther are designed to spin more slowly. Salient: Does the ball actually
Posted on: 10/27/2009 2:29 PM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9206368

RE: Golf ball dimples
[quote]ORIGINAL: banktoturn Your guess as to the mechanism by which distance balls acquire lower spin rates doesn't happen to be the one that the ball manufacturers give, but it doesn't really matter. The salient observation is that balls intended to fly farther are designed to spin more slowly. Salient: Does the ball actually spin more slowly by design intent? or does the ball spin more slowly because the energy imparted by the club , is better transferred into forward motion Sorta like a super ball. Energy is a tricky thing you have to account for all of it the energy could either be used for A- rotation or B- forward motion You can't have yer Kate n Edith too. Perhaps someone has wind tunnel documentation which prooves otherwise. Anyone? .
Posted on: 10/27/2009 2:01 PM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9206286

RE: Golf ball dimples
[quote]ORIGINAL: banktoturn [quote]ORIGINAL: hugger-4641 [quote]ORIGINAL: banktoturn [quote]ORIGINAL: hugger-4641 After this I guess the next question would be: If you could a hit another smooth ball and a dimpled ball with all variables equal but with a perfect back spin, which would go farther? Then we could compare the numbers and know which force actually has more effect. [/quote] hugger-4641, The dimpled ball would go further, which is why they put dimples on them. banktoturn [/quote] Yes, I think we all agree on that, the question is which force contributes the most, ''lift'' from the spinning (magnus effect), or reduced loss of velocity due simply to reduced drag from the dimples? [/quote] hugger-4641, I don't know for sure, but my guess is that the dimples are more important. I base this guess on 3 things: 1) my observation that very worn range balls don't fly as far as new ones (a very obvious difference, when witnessed), 2) balls marketed as ''distance'' balls tend to have lower spin rates, and 3) the aspect ratio of a golf ball is so low that generating a lot of lift causes a big drag penalty. banktoturn [/quote] As long as we are all guessing -try this guess A worn golf ball may not store as much energy (from the club) . old balls may lose some of their "bounce" (Don't we know it) Distance balls MAY flatten more when hit by the club and therefore may not be set into rotation as easily as a harder ball-which MAY thru the angle of club contact - tend to ratate faster from the impact If that concept is too hard to grasp-consider hitting a steel sphere . the contact area of th ball will remain smaller and therefor (I love college talk), the "english" put on th ball will be more than that put on a softer surface -which flattens before going into motion My next slide please.
Posted on: 10/27/2009 12:45 PM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9206048

RE: Golf ball dimples
Do the younger golf balls have pimples instead of dimples?
Posted on: 10/26/2009 8:39 AM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9202708

RE: Elevator SNAPROLL
You can ignore further helpful info of that type-
Posted on: 10/23/2009 11:31 PM by Author "dick Hanson" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=9197484