[RCSE] 2 meter and how it fits
After lurking and reading the many comments re 2 meter at the NATS I figured it was time to submit my dime's worth.. Let's first look at how 2 meter differs from the only other TD class (unlimited).. Because there really are just 2 true model classes for soaring for the major TD classes at the NATS (based on wing-span of course)... Again, these are based on wing-span, just like our full-scale counterparts... With the span limited to 2-meters as compared to unlimited planes we're working with the following span-based performance limitations less aspect ratio, limited visual profile at a distance, shorter glide ratio, generally higher wing loadings. This creates an entirely different flying environment and potential strategy for dealing with a given task. As I've read from a couple contributors, the limitation of size makes the 2 meter a bit more difficult to achieve a given task at times. This is something that makes 2 meter unique as compared to unl. span planes, whether full-house or limited function (the RES class)... One of the tenets laid out by Dan Pruss was that a soaring champion should show abilities in multiple disciplines and various aspects of Soaring.. Within the practical realm of the Soaring NATS in which we deal, 2 Meter is the other discipline.. There is no other. If you take a look at our recent NATS Champs, the Dan Pruss Award has required excellence in both disciplines.. This should not change.. There have been other numerous comments referring to 2 meter as an entry level class. While it's true that many of us started with 2 meter planes like the Gentle Lady, in fact they were RES planes. At the NATS level, the competitive end of 2 meter can't be viewed as such. The entry level category (and throw-back class) is RES. It was before it became a rule-book category. Those that were involved in the early years of the present NATS structure might remember that we added RES/NOS at the end of the NATS week as sort of a laid back way to finish the week, replacing Sportsman's F3B (which occasionally was anything but). It was an easy day of relaxed competition before we all went home. If we want more RES rounds, maybe we should fly just RES on the last day. There is a fair amount of cross-over/redundancy on RES/NOS day anyway. Maybe another event (like one of the Woody Majors) could host a Nostalgia Championship for those so inclined. my dimes worth RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
[RCSE] Re: Optimum aspect ratio - induced drag and span
Yes, but also what's happening (for a fixed wing span) is a trade off between wing loading and induced drag. Re (at least for DLG chords and up) is a variable but not the dominant one. As you increase aspect ratio (reduce chord for a fixed wing span), induced drag goes down but wing loading goes up. The wing loading will eventually degrade your sink rate more than the aspect ratio improves it. Although the wing weight scales with area, the total weight does not (fuselage, tail surfaces, ancillary equipment). Re will hurt here as well (both Cd and Cl) but it's primarily the loading (except perhaps at very small chords). On the other end, lower aspect ratio gives a lower wing loading but increased induced drag (Cl^2/(Pi * AR). Dave, you should know that for a fixed wing span, you need to be talking about total drag, not a drag coefficient, because you are changing the wing area when you change the aspect ratio. Total induced drag depends on the span only (for a constant weight and flight speed). Changing aspect ratio with a fixed span does not affect induced drag (if we ignore that the weight of the structure changes). Induced drag is proportional to the span loading squared (the formula below is obtained by manipulating the one above Cdi=Cl^2/(Pi*AR)): D = (W/L)^2/(Pi*q), where q = rho*V^2/2 Therefore with a fixed span, you can easily find a wing area that gives you the best L/D ratio (parasite drag = induced drag). But that maybe still not the best design depending on your objectives. The main trade-off variables are min flight speed (affects turn radius), best L/D ratio, and high speed performance, all of which are directly affected by the wing area. Obviously, reducing the weight and parasite (fuselage, tail) drag allows to improve all of the criteria because the optimum wing area becomes smaller. Comments and corrections are most welcome. Regards, Oleg. RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
[RCSE] Fw: f3j team wanted
- Original Message - From: Rick Bothell Sent: Thursday, February 17, 2005 10:57 AM To: [EMAIL PROTECTED] Subject: f3j team wanted Wanted: To either form a 4 person F3J team or to join a team that is short a flyer to fly in the Soaring in the Rockies on May 28,29. Denver, Colorado and/or the NATS .Good chance I can find one team mate here in Arizona. I have equipment, knowledge, and can tow. Placed 5th in 2003 F3J Soaring in the Rockies. Please e-mail me if you are interested. Thanks, Rick Bothell, Prescott Valley, AZ
[RCSE] Re: Hey Melborne Australia, I'll be there Friday morning!
Hi Gordy, Just happened to see your post about being in Melbourne. What sort of soaring were you interested in? How long are you here for? Did you bring any planes?? :) I'm mostly into slope soaring but I don't know if I can get out anywhere this weekend... Nevertheless, you're welcome to get in touch if you'd like some info about flying sites etc. Email: anton AT primarykey DOT net DOT au or phone: 9593 9550 (preferably after 10am if calling on the weekend! :p ). I'll give you the main flat-field address for soaring: Directions from VARMS site guide: VARMS (Victorian Association of Radio Model Soaring) Briggs Field Wantirna South Melways Map 72, C2-D2 Opposite Jenkins' Orchard, with red, green yellow apple sign. Gravel driveway South off High Street Road, enter through gate and proceed down track to car park left of hut. There will most likely be guys flying there on Sat and Sun if the weather is not too wet. Enjoy your stay! Anton -- AntonL AntonL's Profile: http://www.rcgroups.com/forums/member.php?action=getinfouserid=28609 View this thread: http://www.rcgroups.com/forums/showthread.php?threadid=337195 RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
[RCSE] ATTN: Sharon 3.7 x-tail owners, need input
Had all but decided on Tempest when the water got muddy. Someone(read Edgar Soaring Junkie) suggested I consider the Sharon. So, I'm asking for input. Probably the main criteria I have is that it be able to hi-start. I do not have a winch readily available to me(and the club winch has seen better days). I am able to get 23#'s of pull out of my hi start. Which was adequate for my Artemis 5mph +, but really iffy for 1-3 mph. That aside, does it require constant attention with the sticks? I'm a Sunday Flyer and I am looking for 'relaxed' flying. I have some open class flying experience. I have a Sun 3.2m electric powered by Hacker 50 that I am able to handle, but never really got comfortable with the Artemis V tail. Any and all suggestions would be appreciate. Yes I'm the same guy who asked about the Tempest last week. Appreciate the band width. Stan RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
RE: [RCSE] Re: Hey Melborne Australia, I'll be there Friday morning!
Did you bring any planes?? Are you kidding? Gordy never goes anywhere without an airplane; he will likely be buried with his Pike Superior. :) -Original Message- From: AntonL [mailto:[EMAIL PROTECTED] Sent: Friday, February 18, 2005 05:33 To: soaring@airage.com Subject: [RCSE] Re: Hey Melborne Australia, I'll be there Friday morning! Hi Gordy, Just happened to see your post about being in Melbourne. What sort of soaring were you interested in? How long are you here for? Did you bring any planes?? :) I'm mostly into slope soaring but I don't know if I can get out anywhere this weekend... Nevertheless, you're welcome to get in touch if you'd like some info about flying sites etc. Email: anton AT primarykey DOT net DOT au or phone: 9593 9550 (preferably after 10am if calling on the weekend! :p ). I'll give you the main flat-field address for soaring: Directions from VARMS site guide: VARMS (Victorian Association of Radio Model Soaring) Briggs Field Wantirna South Melways Map 72, C2-D2 Opposite Jenkins' Orchard, with red, green yellow apple sign. Gravel driveway South off High Street Road, enter through gate and proceed down track to car park left of hut. There will most likely be guys flying there on Sat and Sun if the weather is not too wet. Enjoy your stay! Anton -- AntonL AntonL's Profile: http://www.rcgroups.com/forums/member.php?action=getinfouserid=28609 View this thread: http://www.rcgroups.com/forums/showthread.php?threadid=337195 RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
[RCSE] Best 2m electric?
Hi guys, I haven't been flying as much as I use to, but when I do, I find my little 1.5m Koleos electric is the planeI grab. Its small and lightenough I can fly from the small field behind my house where my larger electrics aren't comfortable. The Koleos is getting pretty worn out, and I am looking for something slightly bigger, around 2m. What's available as an electric in this size? Anything with AVA-type construction (very light)and rudder/elevator/spoiler? TIA Stan Sadorf
RE: [RCSE] Best 2m electric?
Wind Dancer! http://www.polecataero.com/ Based on the Allegro E-Lite. RES, built up, lightweight. A few guys were flying thesefor Spd 400 during the 2004 ESWC in New Mexico.Two of themplacedsecond and third. Aradhana Singh Khalsa Registrar 2005 F5J Electric Soaring Challenge October 14-16th, 2005 http://www.soarabq.org
[RCSE] Pivoting laser level
Someone recently was looking for a laser that would project a crosshairs at the floor. I don't remember who it was (sorry) but I came across a Bushnell PivotPoint Laser Level # 82897 at the local Fry's grocery store that fits the bill. It will project a dot, line , or crosshairs anywhere from straight up to straight down. It was on sale for $14.97. Hope this helps. Barry Murrill Phoenix, AZ RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
Re: [RCSE] ATTN: Sharon 3.7 x-tail owners, need input
Hi Stan For me the best all around ship is the new Escape Lt. from Aero Model http://www.aero-model.com/ProductDe...x?productID=429 It only weighs 68 oz (it will go up on a good hi-start or a weak winch with no problem) but can carry, safely, up to 24 oz. of ballast. So you have a plane that is light enough for the deadest days and strong enough to carry 9 or 24 oz. (this is the 2 ballast bar set available from Aero Model for $49.00) of ballast for the windiest days. I love the plane and have 2. You can see them and the slight mods that I made to them on rcgroups/thermal/Escape Lt. or use the link below. http://www.rcgroups.com/forums/show...690#post3174690 Maurice - Original Message - From: Stan Myers [EMAIL PROTECTED] To: Soaring Digest soaring@airage.com Sent: Friday, February 18, 2005 8:26 AM Subject: [RCSE] ATTN: Sharon 3.7 x-tail owners, need input Had all but decided on Tempest when the water got muddy. Someone(read Edgar Soaring Junkie) suggested I consider the Sharon. So, I'm asking for input. Probably the main criteria I have is that it be able to hi-start. I do not have a winch readily available to me(and the club winch has seen better days). I am able to get 23#'s of pull out of my hi start. Which was adequate for my Artemis 5mph +, but really iffy for 1-3 mph. That aside, does it require constant attention with the sticks? I'm a Sunday Flyer and I am looking for 'relaxed' flying. I have some open class flying experience. I have a Sun 3.2m electric powered by Hacker 50 that I am able to handle, but never really got comfortable with the Artemis V tail. Any and all suggestions would be appreciate. Yes I'm the same guy who asked about the Tempest last week. Appreciate the band width. Stan RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
RE: [RCSE] ATTN: Sharon 3.7 x-tail owners, need input
Stan, I picked up this very plane (incidentally pushed by the very same person. Edgar gets around ;-) last November. It's big, but that also means it's heavy. If you high-start is iffy for the Artemis, it's not going to be enough for the Sharon. If you go with the Sharon, either upgrade the High-start, or volunteer to take over winch maintenance. That said, the Sharon is a great flyer. First flight I set it up per factory recommendations (except the tow hook is too far forward). Launch climb was aggressive it required 0 trim adjustments. (gotta love the repeatability of molded planes) Nice balance of stability vs. showing air. I'm sure you could tweak the CG if you want more stability. -l -Original Message- From: Stan Myers [mailto:[EMAIL PROTECTED] Sent: Friday, February 18, 2005 8:27 AM To: Soaring Digest Subject: [RCSE] ATTN: Sharon 3.7 x-tail owners, need input Had all but decided on Tempest when the water got muddy. Someone(read Edgar Soaring Junkie) suggested I consider the Sharon. So, I'm asking for input. Probably the main criteria I have is that it be able to hi-start. I do not have a winch readily available to me(and the club winch has seen better days). I am able to get 23#'s of pull out of my hi start. Which was adequate for my Artemis 5mph +, but really iffy for 1-3 mph. That aside, does it require constant attention with the sticks? I'm a Sunday Flyer and I am looking for 'relaxed' flying. I have some open class flying experience. I have a Sun 3.2m electric powered by Hacker 50 that I am able to handle, but never really got comfortable with the Artemis V tail. Any and all suggestions would be appreciate. Yes I'm the same guy who asked about the Tempest last week. Appreciate the band width. Stan RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
Re: [RCSE] ATTN: Sharon 3.7 x-tail owners, need input
Sorry the links didn't work. Here are corrected ones. http://www.aero-model.com/ProductDetails.aspx?productID=429 http://www.rcgroups.com/forums/showthread.php?p=3174690#post3174690 - Original Message - From: Stan Myers [EMAIL PROTECTED] To: Soaring Digest soaring@airage.com Sent: Friday, February 18, 2005 8:26 AM Subject: [RCSE] ATTN: Sharon 3.7 x-tail owners, need input Had all but decided on Tempest when the water got muddy. Someone(read Edgar Soaring Junkie) suggested I consider the Sharon. So, I'm asking for input. Probably the main criteria I have is that it be able to hi-start. I do not have a winch readily available to me(and the club winch has seen better days). I am able to get 23#'s of pull out of my hi start. Which was adequate for my Artemis 5mph +, but really iffy for 1-3 mph. That aside, does it require constant attention with the sticks? I'm a Sunday Flyer and I am looking for 'relaxed' flying. I have some open class flying experience. I have a Sun 3.2m electric powered by Hacker 50 that I am able to handle, but never really got comfortable with the Artemis V tail. Any and all suggestions would be appreciate. Yes I'm the same guy who asked about the Tempest last week. Appreciate the band width. Stan RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
Re: [RCSE] Re: Optimum aspect ratio - induced drag and span
There was a study done by Blaine K. Beron-Rawdon of Envision Design, at least a few years ago. I will post this to news:rec.models.rc.soaring for your perusal. The study spanned several wingpans and aspect ratios and has a document that summarizes the results. E-mail if you need a copy directly. Tom Koszuta Western New York Sailplane and Electric Flyers Buffalo, NY - Original Message - From: [EMAIL PROTECTED] To: [EMAIL PROTECTED]; Soaring@airage.com Sent: Friday, February 18, 2005 12:59 PM Subject: [RCSE] Re: Optimum aspect ratio - induced drag and span So which term dominates is not completely clear without running through a bunch of numbers and making some estimates of weights, planforms, etc. RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
Re: [RCSE] Re: Optimum aspect ratio - induced drag and span
Dave, A while back I sent you some comments on my admittedly amateurish approach to 2M based on Martin Simons work back in the 80's. AR's are around 6 - max chord around 16, min = around 8 Would you care to discuss how this approach fits into your current discussion? RVC At 12:59 PM 2/18/2005 -0500, you wrote: In a message dated 2/18/2005 9:11:49 AM Central Standard Time, Soaring@airage.com writes: Changing aspect ratio with a fixed span does not affect induced drag (if we ignore that the weight of the structure changes). Induced drag is proportional to the span loading squared (the formula below is obtained by manipulating the one above Cdi=Cl^2/(Pi*AR)): D = (W/L)^2/(Pi*q), where q = rho*V^2/2 Oleg, This does not seem to be dimensionally correct. In english units D is in lbs., V is in ft/sec, W/L is in lb/ft^2, and rho (density) is in slugs/ft^3 (gotta love those english density units!). Converting from density to weight (density * g ) gives the left side in lbs and the right side in lbs/ft^2. I believe the missing term is the average chord (Cavg^2). Absent that, I'll generally be in agreement with your comments with a few caveats: Assuming the following is correct (my derivation of the same manipulation you've done using the equations Lift = q * Cl * A,Drag = q * Cd * A, where A is the wing area): RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
[RCSE] Anyone have an F3B model for sale? Need practice ship...
Hi folks, Before I get lured away by a friend wanting to split shipping on some scale models, does anyone have any F3B models for sale that would make good practice ships? There's a group of us who have decided to learn to fly the tasks properly this season, and from what I've been learning my Erasers might not cut it. Then again, I could solve the problem by just doing both :) Cheers, Adam Adam Till Mechanical Engineer 403-270-9200 (ext 154) 403-270-0399 (Fax) UMA Engineering Ltd. 2540 Kensington Road NW Calgary AB, Canada T2N 3S3 RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
[RCSE] Re: Optimum aspect ratio - induced drag and span
This does not seem to be dimensionally correct. In english units D is in lbs., V is in ft/sec, W/L is in lb/ft^2, and rho (density) is in slugs/ft^3 (gotta love those english density units!). Converting from density to weight (density * g ) gives the left side in lbs and the right side in lbs/ft^2. I believe the missing term is the average chord (Cavg^2). I have to admit that I am not well versed in English units (and probably will never be), but here is the dimensionality check in SI units for you: D(N) = [ W(N)/L(m) ]^2 / [Pi*q(kg/m*s^2)], (note, that W = m*g (N = kg*m/s^2)), therefore for the units: N = [N^2/m^2]/[kg/m*s^2] = N^2*s^2/kg*m = N^2/N = N So nothing is missing, there is no average chord there. Actually I just tried the same check in English units and it all works out the same: lb = [lb^2/ft^2]/[slug/ft*s^2] = lb^2*s^2/slug*ft = lb^2/lb = lb You did not need to convert mass density into weight density. I stand by my previous statement: that total induced drag does not depend on the AR for a fixed span (which is aero 101 really). And I just learned something about English units! Best regards, Oleg. RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
[RCSE] Re: Optimum aspect ratio - induced drag and span
A number of things trade off. As aspect ratio goes up, Cavg goes down while W/L goes up (both numerator effects). Meanwhile, V^2 goes up (denominator effect) as W/L goes up for a relatively constant Cl (assuming the plane maintains approximately the same AoA at min sink or max L/D, whichever you choose). Dave, Just noticed another strange assumption in your arguments. I don't see how increasing AR changes W/L. It is constant unless you want to account for mass changes due to AR changes, which is true in reality, but again for a fixed span the weight of the wing is usually proportional to the wing area, therefore W/L will actually decrease for higher AR (smaller wing area). Regards, Oleg. RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
Re: [RCSE] 2 meter and how it fits
What Mike said!!! My new custom 2M is on the board. I love my Open Class ships, but I really enjoy the challenge of 2M. A high placing finish with a 2M means much more to me than the same finish with an open class ship. I'll keep both spans and be very happy flying both (and RES too). There is room for everybody. Justin Ammon CEO EdgeRC Inc 480-593-2458 www.edgerc.com [EMAIL PROTECTED] Practice does not make perfect...Only perfect practice makes perfect. - Original Message - From: Mike Stump [EMAIL PROTECTED] To: soaring@airage.com Sent: Friday, February 18, 2005 5:49 AM Subject: [RCSE] 2 meter and how it fits After lurking and reading the many comments re 2 meter at the NATS I figured it was time to submit my dime's worth.. Let's first look at how 2 meter differs from the only other TD class (unlimited).. Because there really are just 2 true model classes for soaring for the major TD classes at the NATS (based on wing-span of course)... Again, these are based on wing-span, just like our full-scale counterparts... With the span limited to 2-meters as compared to unlimited planes we're working with the following span-based performance limitations less aspect ratio, limited visual profile at a distance, shorter glide ratio, generally higher wing loadings. This creates an entirely different flying environment and potential strategy for dealing with a given task. As I've read from a couple contributors, the limitation of size makes the 2 meter a bit more difficult to achieve a given task at times. This is something that makes 2 meter unique as compared to unl. span planes, whether full-house or limited function (the RES class)... One of the tenets laid out by Dan Pruss was that a soaring champion should show abilities in multiple disciplines and various aspects of Soaring.. Within the practical realm of the Soaring NATS in which we deal, 2 Meter is the other discipline.. There is no other. If you take a look at our recent NATS Champs, the Dan Pruss Award has required excellence in both disciplines.. This should not change.. There have been other numerous comments referring to 2 meter as an entry level class. While it's true that many of us started with 2 meter planes like the Gentle Lady, in fact they were RES planes. At the NATS level, the competitive end of 2 meter can't be viewed as such. The entry level category (and throw-back class) is RES. It was before it became a rule-book category. Those that were involved in the early years of the present NATS structure might remember that we added RES/NOS at the end of the NATS week as sort of a laid back way to finish the week, replacing Sportsman's F3B (which occasionally was anything but). It was an easy day of relaxed competition before we all went home. If we want more RES rounds, maybe we should fly just RES on the last day. There is a fair amount of cross-over/redundancy on RES/NOS day anyway. Maybe another event (like one of the Woody Majors) could host a Nostalgia Championship for those so inclined. my dimes worth RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
Re: [RCSE] Re: Optimum aspect ratio - induced drag and span
Is the problem the term aspect ratio? For his project he's probably using a plank wing. Aspect ratio is a term that can be applied. What happens to the same span if the planform becomes elliptical? Do you still apply the same aspect ratio? Out of practical experience there is a big difference between a plank and an ellipse, even with the same foil (most noticeable at higher speeds). I think we've spun away from the original premise of how aspect ratio and glide rate are related, but it's obvious that more variables quickly come into effect. I did a similar science fair project in high school where I tried two different foils on the same planform and airframe. I used the school gym, turned out the lights and recorded the flight by leaving my camera lens open and using a strobe light. The project basically proved that the break through airfoil I was trying didn't work at all. The fact that I got to integrate a glider and photography was probably more important. I still have one of my favorite pictures, where the glider was flown, banked hard left towards the camera and flew by, all recorded by the strobe. I think I was blinking for about a week after that project. JE -- Erickson Architects John R. Erickson, AIA I stand by my previous statement: that total induced drag does not depend on the AR for a fixed span (which is aero 101 really). And I just learned something about English units! Best regards, Oleg. RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
Re: [RCSE] Re: Optimum aspect ratio - induced drag and span
Sorry, The attachment seems to be prohibited by the newsgroup. I will make the attempt soon or later to get this on my website, but for now, I will honor e-mail requests for those who need the documents. Or should I e-mail it to the exchange??? (one no and I will not) Tom Koszuta Western New York Sailplane and Electric Flyers Buffalo, NY - Original Message - From: Thomas Koszuta [EMAIL PROTECTED] To: Soaring@airage.com Sent: Friday, February 18, 2005 1:27 PM Subject: Re: [RCSE] Re: Optimum aspect ratio - induced drag and span There was a study done by Blaine K. Beron-Rawdon of Envision Design, at least a few years ago. I will post this to news:rec.models.rc.soaring for your perusal. The study spanned several wingpans and aspect ratios and has a document that summarizes the results. E-mail if you need a copy directly. Tom Koszuta Western New York Sailplane and Electric Flyers Buffalo, NY - Original Message - From: [EMAIL PROTECTED] To: [EMAIL PROTECTED]; Soaring@airage.com Sent: Friday, February 18, 2005 12:59 PM Subject: [RCSE] Re: Optimum aspect ratio - induced drag and span So which term dominates is not completely clear without running through a bunch of numbers and making some estimates of weights, planforms, etc. RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
[RCSE] Breakdown of Wood Crafters 05 enteries.......
Gentlemen, Here is the breakdown of how the Wood Crafters 05 participants have chosen to have fun flying their woody sailplanes at the AMA flying site in Muncie, IN , May 26 thru 29, 2005. Hopefully, this will give other persons or clubs insight into the events people enjoy and incorporate these ideas into their future events. Without a doubt, Wood Crafters is all about having fun with woody sailplanes and flying with woody enthusiasts. This years event will have some additions, changes and deletions from what we did last year. Ch 11, 42, 45 are available for the Thursday and Friday Soar In Reunion and the Saturday and Sunday Soar In Championship. Contact me if you want to play on one of these open freq. Soar In Reunion event entries: 2 Minute Ladder 30, Longest Flight 26, Fun Fly Only 1, Man on Man 60 Mini Hi Start 16, Man on Man Windfree Ray's Hi Start 7,Man on Man Ray's Mini Fun Scale (64) Mini Hi Start 7, Soar In Championship Class entries:Scale 21 (Gordon's Rules 8, Ray's Fun Scale 13), Best OLY ll 10, Best Challenger 6, Best Astro Jeff 5, 2 Meter Unlimited 25,100 RES 34,Unlimited 35. Special Awards: People's Choice for Best Scale and Wood Crafter's Award to person selected for Outstanding Contributions to the promotion of RC Soaring. Free Drawing for Bench size Drill Press and other electric wood working tools and various other prizes. Nothing but fun at Wood Crafters 05 For More Wood Crafters info .. go to the Wood Crafters page on my Sky Bench web site. Ray Hayes http://www.skybench.com Home of Wood Crafters Ray Hayes http://www.skybench.com Home of Wood Crafters RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
Re: [RCSE] ATTN: Sharon 3.7 x-tail owners, need input
At 10:26 AM 2/18/05 -0600, Stan Myers wrote: Had all but decided on Tempest when the water got muddy. Someone(read Edgar Soaring Junkie) suggested I consider the Sharon. So, I'm asking for input. Probably the main criteria I have is that it be able to hi-start. I do not have a winch readily available to me(and the club winch has seen better days). I am able to get 23#'s of pull out of my hi start. Which was adequate for my Artemis 5mph +, but really iffy for 1-3 mph. That aside, does it require constant attention with the sticks? I'm a Sunday Flyer and I am looking for 'relaxed' flying. I have some open class flying experience. I have a Sun 3.2m electric powered by Hacker 50 that I am able to handle, but never really got comfortable with the Artemis V tail. Any and all suggestions would be appreciate. Yes I'm the same guy who asked about the Tempest last week. Appreciate the band width. Stan Stan, I have a Sharon, Artemis and a couple of Icons so I might be able to provide some input. I bought my Sharon for an early morning/light lift F3J tool. The Sharon will handle a brutal two-man tow without complaints. I'm not sure what you would consider constant attention to the sticks, but I think the Sharon is a nice flyer, with one exception. During landing, the Sharon doesn't like a lot of radical flap modulation, I'm guessing that this is due to the large flap chord. Otherwise, she's got great legs, hangs well in light conditions and is great fun to fly. I've regularly hi-started my Sharon on 25' of 1/2 tubing with 50' of mono, but I'm probably pulling around 40+ lbs at launch. My Sharon came with a fixed position towhook and I replaced it with an adjustable version as well as pushing the CG aft quite a bit. Interestingly, my Artemis Lite (v-tail) is still my favorite TD plane to fly. Tom Hoopes - ([EMAIL PROTECTED]) -- Hoopes Designs - Taking the hassle out of wing wiring harnesses http://www.hoopesdesigns.com
[RCSE] For Sale - Extreme
Selling my back up Extreme cross tail sailplane. This is the LT version in yellow and dark blue. The wing and tail are practically new with very few flights. It is equipped with HS 125 superflat on the ailerons, JR 368s on the flaps and elevator and a HS 81mg for the rudder. Includes Hitec Super Slim receiver and 1100ma battery. A set of individual wingbags available as an option. Asking $1075 for RTF plus shipping. E-mail me at [EMAIL PROTECTED] for questions. Thanks Chuck RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
[RCSE] Re: Optimum aspect ratio - induced drag and span
In a message dated 2/18/2005 12:47:33 PM Central Standard Time, [EMAIL PROTECTED] writes: D(N) = [ W(N)/L(m) ]^2 / [Pi*q(kg/m*s^2)], (note, that W = m*g (N = kg*m/s^2)), therefore for the units: N = [N^2/m^2]/[kg/m*s^2] = N^2*s^2/kg*m = N^2/N = N So nothing is missing, there is no average chord there. ** Oleg, OK, we've got a nomenclature difference (it's always the communication issues, isn't it?) My standard usage is W/L as Wing Loading which is Weight / Area = Weight / (Span * Cavg) I believe your W/L refers to the Weight (W) divided by the Span (L) (- which I usually call S). Hopefully this clarifies things. If you multiply the W/L term by Cavg/Cavg you get Cavg * Weight / (L*Cavg) = Cavg * Weight / Area and things are consistent. Works the same in english, cgs, mks, etc. Sorry for the digression but with this sorted out, the result is mathematically the same. The reason I prefer to keep it in the wing loading form is that the scaling is a bit more apparent (to me). The lift force equation relates these two as: Weight/Area (wing loading) = q * Cl (since Lift has to equal Weight for steady flight) Since q contains the V^2 term, Wing loading is proportional to V^2. - assuming Cl stays about the same. The derived Drag formula then scales as W^2 / L^2 / V^2 ~ Cavg^2 * Wing Loading)^2 / V^2 or Drag (induced) scales as Cavg^2 * (Wing Loading) For a fixed span, as aspect ratio increases, the wing loading does not go up as fast as Cavg goes down so Cavg wins. For a fixed Cavg, as aspect ratio increases, wing loading will go up so drag should increase (??) * I don't see how increasing AR changes W/L. It is constant unless you want to account for mass changes due to AR changes, which is true in reality, but again for a fixed span the weight of the wing is usually proportional to the wing area, therefore W/L will actually decrease for higher AR (smaller wing area). * Again, this really depends on the assumptions one makes when doing an analysis. This was discussed most recently in RCSD, I believe the Jan 2004 or Feb 2004 issues for a 2M design (server seems to be down right now but available as PDF files form the general site: _http://www.b2streamlines.com/RCSD.html_ (http://www.b2streamlines.com/RCSD.html) .) My assumption is that you have to look at the entire package. That means keeping a constant weight for the fuselage and radio equipment, and scaling the wing and tail surfaces for aspect ratio (constant volume coefficients are good enough for the stabs). If you weigh all of those components, you'll usually find that the wing is less than half of the total aircraft weight (take out the servos and it's even less). So as you scale down the wing area, the weight of the whole aircraft doesn't come down linearly with the wing area. Since those analyses were for a fixed class (2M, for instance), as you change Aspect Ratio, you reduce the average chord at a fixed wingspan. Although the wing weight scales down with area, the weight of the fuselage and ancillary equipment stays relatively constant. Thus the wing loading will go up. If you let the span be unconstrained then the options are much more flexible. But when you get to the open class design, the improved efficiency from the higher achievable aspect ratios (at a reasonable wing loading) set them quite a bit apart from 2M. Here it's the aspect ratio and loading effects that dominate, not Re. So bigger flies better, but not strictly due to Re effects. Meanwhile, I hope the science fair project is going OK! Thanks - and sorry for the confusion on the terminology. - Dave R RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
[RCSE] Re: Optimum aspect ratio - induced drag and span
Dave, OK, we've got a nomenclature difference (it's always the communication issues, isn't it?) In my original message I said the induced drag is proportional to SPAN LOADING, not wing loading, for a fixed span wing. That is really all I am trying to show you: Di = (W/L)^2 / (Pi*q), where W = weight, L = span, q = rho*V^2/2 Sorry for the digression but with this sorted out, the result is mathematically the same. The reason I prefer to keep it in the wing loading form is that the scaling is a bit more apparent (to me). You can keep it in any form you want, the result is the same, total induced drag is not dependant on the AR for a fixed span. This is really a simple aerodynamic axiom that does need to be argued about. I guess I am not a high enough authority to take my word on it :-) For a fixed span, as aspect ratio increases, the wing loading does not go up as fast as Cavg goes down so Cavg wins. For a fixed Cavg, as aspect ratio increases, wing loading will go up so drag should increase (??) By using chord and wing loading you are just clouding the issue. Yes, W/L = W*C/S, but you cannot change C (chord) without changing S (area) for a fixed span. It is still SPAN LOADING, Weight/Span. And yes, wing loading DOES go up as fast as the chord goes down. Change AR all you want, you are not changing SPAN LOADING. This is just elementary algebra actually, not even aerodynamics. My assumption is that you have to look at the entire package. I agree. I was only correcting you on one point. Total induced drag does not depend on the AR, only on the span, weight, speed. I hope you can work out the algebra and convince yourself in that. Best regards, Oleg. PS. Apologies to the list for dragging this issue so far. I was not really contributing to the original topic here, just could not let the incorrect statement go :-0 RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
[RCSE] Re: Optimum aspect ratio - induced drag and span
I didn't go through it to see if this looks like the source of confusion, but don't forget that bugaboo of English units, the pound-force. Commonly abbreviated lbf, the pound force is defined as the force required to accelerate one pound-mass at a rate equal to l standard G, 32.17417 foot/second. If you write pound, and are not careful to specify whether you mean one pound-mass or 32.17417 pound-mass foot / second^2, you can get mighty confused. Most people don't even know there is a difference, of course most people don't know what accleration or force are and couldn't tell you the difference between their mass and their weight. Though raised in the English unit U.S., I always go metric when I want to be sure of not screwing up a units calculation. Gotta love the way so many of the conversion factors are exactly one. Only idiots and engineers use poundals. That is just asking for trouble, sometimes trouble in the multi-millions of dollars. I have seen people use the kilogram-force as a supposedly metric unit. I think that is another stupid way to get into trouble. Use Newtons. Once you figure out what they mean, and how to use them, you too will appreciate the beauty of a system that has most of its units convert by factors of one, and that does not stick some oddball number, like Earths gravity, into a basic unit. Yes, I know the metric units are wholly arbitrary, but they are arbitrary in a whole lot less confusing way than English units. -- Mark Holm [EMAIL PROTECTED] RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
Re: [RCSE] 2 meter and how it fits
After lurking and reading the many comments re 2 meter at the NATS I figured it was time to submit my dime's worth.. Let's first look at how 2 meter differs from the only other TD class (unlimited).. Because there really are just 2 true model classes for soaring for the major TD classes at the NATS (based on wing-span of course)... Again, these are based on wing-span, just like our full-scale counterparts... With the span limited to 2-meters as compared to unlimited planes we're working with the following span-based performance limitations less aspect ratio, limited visual profile at a distance, shorter glide ratio, generally higher wing loadings. This creates an entirely different flying environment and potential strategy for dealing with a given task. As I've read from a couple contributors, the limitation of size makes the 2 meter a bit more difficult to achieve a given task at times. This is something that makes 2 meter unique as compared to unl. span planes, whether full-house or limited function (the RES class)... One of the tenets laid out by Dan Pruss was that a soaring champion should show abilities in multiple disciplines and various aspects of Soaring.. Within the practical realm of the Soaring NATS in which we deal, 2 Meter is the other discipline.. There is no other. If you take a look at our recent NATS Champs, the Dan Pruss Award has required excellence in both disciplines.. This should not change.. There have been other numerous comments referring to 2 meter as an entry level class. While it's true that many of us started with 2 meter planes like the Gentle Lady, in fact they were RES planes. At the NATS level, the competitive end of 2 meter can't be viewed as such. The entry level category (and throw-back class) is RES. It was before it became a rule-book category. Those that were involved in the early years of the present NATS structure might remember that we added RES/NOS at the end of the NATS week as sort of a laid back way to finish the week, replacing Sportsman's F3B (which occasionally was anything but). It was an easy day of relaxed competition before we all went home. If we want more RES rounds, maybe we should fly just RES on the last day. There is a fair amount of cross-over/redundancy on RES/NOS day anyway. Maybe another event (like one of the Woody Majors) could host a Nostalgia Championship for those so inclined. Hi Mike, Thanks for your dimes worth. :) I'm curious; who was it that suggested the criteria for the Dan Pruss Award should be different? Regards, Bob Johnson Fond du Lac, WI RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
[RCSE] Test
Test. Seems awfully quiet this evening... RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
