[RCSE] Re: HLG optimization
In a message dated 00-06-09 15:12:56 EDT, [EMAIL PROTECTED] writes: What about high aspect ratio? Your latest design did not converge to a Spectre like planform - did Don S. make a mistake (unlikely) or did you use different objectives/assumptions/etc? While I can't comment on the aerodynamics or assumptions behind the Shpectre, I did observe that it's performance in flight was nearly as good as any other "latest greatest" ship at the IHLGF. However (a BIG however) the SpectreVR fails spectacularly in the practical department. Strength and durability are it's downfall in a contest. Several failure modes manifested themselves under normal contest abuse. Wing skin delamination around the aileron servos. Wing seperation/breakage from aileron root diagonally forward. Wing flex and flutter under full power launches, particularly in wind (even after liberal stiffening with carbon cloth/epoxy at weak areas) These comments based on two seperate planes and pilots with identical problems and similar time in service, but also consider that this service was in a very grueling contest (the Handlaunch World Champs!). To DJ Aerotech's credit, the problems are easily fixable. Mark Navarre - RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
[RCSE] Winch Times
Aloha We on Maui have finally got a winch "Little Big Winch" thanks to Tom Nakagawa. The only problem is we don't know how to use it as we handlaunch everything. Well I have a Hollayday Upstart that we have used on the past three weekends. "Great Stuff" We now have to put tow hooks on our ships, but most of the fliers on Maui are concerned about the structual integrity of their fuses. They don't want to drill a hole in it because it might weaken their airframe and say it looks weird. But thanks to some of the Oahu guys who will be coming down next week for our Maluhia Big Bird Fun Fly. Names like Dave Hill of Predator fame and Peter Schubert two time state champ, and Keith McCllean, From Hawaiian Soaring Leauge. They can show us how to use a winch. Should be a fun and learning exprience for us on Maui. Anyone coming down to Maui are more than welcome to come and fly with us if you're down here for vacation. If you don't have anything to fly you can use my stuff. Aloha, Gerald F. Club Miso RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
[RCSE] Re: HLG optimization (VERY LONG)
From: Joe Jan Wurts [EMAIL PROTECTED] Somewhere around the beginning of the year, I set out to do some systems design, analysis, and optimization work on the... Joe, could you please elaborate a little more on your optimization approach? Oleg, great questions. These questions indicate that you at least understand much of the challenges, if not also how to solve these problems. In short, my analysis tools were: Excel, a vortex lattice code, and an airfoil design and analysis tool that is highly regarded in the aero industry. I used some custom Excel stuff that is formulated to help out in digesting the results from the vortex lattice and airfoil tools. Not very difficult to put together, just the typical eqns, along with some macros and VB. Not anything that is terribly user friendly, but enough for me to do the job. As you probably know, setting up the constraints, and the objective evaluation functions is really the difficult task. All else is just math. As for the piece parts, the wing planform design is optimized considering spanwise lift distribution to get good handling qualities, along with good overall total lift and drag efficiency. This is somewhat intuitive in nature, one has to look at the local lift coefficients along the span in order to arrive at the "handling qualities" part of it. The rest of the stuff is more objective. In addition to the handling qualities, one needs to get a good e (Oswalds efficiency) out of the planform, along with a high useful total lift coefficient (total wing Cl/local Cl). The latter is somewhat in opposition to the handling qualities, but manageable. Also, one should be taking into account the varying local reynolds number along the span in formulating the total aero characteristics of the wing (lift and drag). Also included in the wing optimization process was the weight of the wing. As a first order approximation, the wing weight is a function of the area (skin weight at minimum gage), volume (foam cores for vacuum bagging), along with a second order influence due to total thickness (thin high aspect ratio wings need more spar structure). The spar structure is really not as much of a driver for HLG as one would think, but should be included. As for the tails, a simple trade on tail boom length vs. tail size was made, with a simplistic boom length vs weight eqn, along with tail area vs tail weight eqn. Functional goals included optimizing the minimum sink, mid-range cruise speed L/D, and very low Cl profile drag. Defining a useful objective function here is not a trivial task, and will be left up to the reader. Variables that were traded for the optimization include: planform airfoil(s) wing area tail boom length TE angle as applicable TE length as applicable Fixed values include: Radio gear weight (2ch differing from 4 ch) wing span tail volumes nose pod weight Qualitative ratings include: spanwise local lift distribution cl - cd bucket width with TE deflections Constraints include: airfoil thickness (at servo and and TE) The process is highly iterative in nature. I started off with using an Encore type HLG to get me the scaled Re's along the wing. After getting this, I started whacking at the airfoil development. After developing a few candidate airfoils for evaluation, the planform was brought into consideration for a round of optimization. With the "optimized" airfoil, I did a planform optimization using the developed airfoils. In the case of the poly ship, I ended up doing another round of airfoil optimization, as the optimal aspect ratio increased, driving down the wing area which pushed for another bout of airfoil optimization. This design/analysis/optimization loop is fairly straightforward for the poly ship, but grew some hair for the 4 ch ship. The additional variable of TE deflections added considerably to the design cycle. Also, it made for more qualitative evaluations. Airfoil 1 might produce a better peak efficiency, but airfoil 2 might produce a wider "bucket". Which is better? And how wide should that bucket be to be considered optimal? There is a reason why nobody is selling a program that has an optimal airplane design button. There are just too many qualitative judgments that go into a realistically constrained design. After the first few orbits around the design loop, I tossed in the tail boom optimization as well, and went for another orbit. The result, the toys that I flew at Poway. The poly ship did not get the tail boom iterated, and the 4 ch ship was a bit shorter compared to the optimal, but the min sink sensitivity was really flat between the chosen length and the optimal length. Note: optimal really should have quotes around it. It was optimal by my evaluations, objective functions, and constraints, but might not be optimal by anothers evaluation. Now, you ask my opinions on some of the "skinny" type platforms that are showing up out there. First, I'll make a
[RCSE] RE: [FAIsoaring] F3J USA JUNIOR TRAM AUCTION
What's a wallet?? Oh. That is where people keep their money. What's money??? Klaus Weiss. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] Sent: Wednesday, June 07, 2000 8:15 AM To: [EMAIL PROTECTED]; soaring@airage; FAI Soaring List; F3J F3B List Subject: RE: [FAIsoaring] F3J USA JUNIOR TRAM AUCTION Rumor has it BIG RED SOARING MACHINE has scared Gordy's wallet in to hiding. Come on Gordy it's for the FUTURE OF SOARING!! Smooth Thermals, Karlton "MrMPX" Spindle http://www.MultiplexRC.com -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] Sent: Wednesday, June 07, 2000 7:31 AM To: soaring@airage; FAI Soaring List; F3J F3B List Subject:[FAIsoaring] F3J USA JUNIOR TRAM AUCTION ONLY 13 HOURS LEFT ON THE VOLZ SERVOS, LOOKS LIKE MR. MPX is the TOP BIDDER ON BIG BLUE will this madness ever end, GORDY where are you?. http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItemitem=347260482 winmail.dat
[RCSE] At last - if works!
I have for a while battled with a Graupner electric ducted fan pod, Graupner # 1374, that is designed for 600 motors (like the Graupner Speed 600 BB), and have previously tested a similar fan (Graupner # 1379) which is designed for 400s. I modified one of my 400 fans for one of my Aveox 1114/4Ys, just needing to drill out the collet to take the slightly thicker shaft of the Aveox. Worked OK, but I figured out that fitting such a motor to the 600 size would be a much better idea. The design is neat, made out of CF epoxy with a 5 blade rotor and a four blade stator (seven stator blades on the 400 size). Rotor diameter is 58 mm for the 400 and 75 mm for the bigger unit - the smaller weighs just over an oz and the bigger less than two! The motors are fitted to an aluminium 'lid' that screws into the centre of the rotor, and the cables are supposed to go out at the sidem but I run mine out the back (three power cables, plus the five for the control electronics, takes quite some room)! I sawed a slit in the nacelle and the centre body so I can run the cables out behind each other in an orderly and low-drag fashion. With eight 500AR cells and the smaller one consumed about 12A, while the bigger has not yet been tested with an amp meter, but the static pull is amazing! With more cells it would run even better, but I'm afraid it might desintegrate! I first used one of the microprocessor-controlled ESC, but nothing happened, it blinked one with its red LED and that was that, so I now use an oldfashioned one, twice as big and much heavier! The 600 fan fits to the 1114/4Y very well, but you have to drill new holes for the securing bolts in the aluminium 'lid' and do the previous mentioned cut for the cables! Glory to Dremel cut-off wheels! And a slight enlargement of the lid's centre hole to fit the front bearing housing on the 1114/4Y - I think the 1000 series would fit as is - but I have none to try on! The advantage with using a thinner motor is that cooling air has ample access thrpugh the cooling holes in the lid and similar holes the rotor's centre :-)! Very well though out! I'll test it later with a Kyosho car motor! If the ordinary cansized Aveoxes had a 3.2 mm axle I would try those, but alas, there is no chance that the fan-securing collet of the bigger can be drilled out that much! So one duff Aveox L60 ESC ... But a great fan! Will be test flown on a Zagi THL and then migrate to a Mongo Jr, together with the other one! And the batteries will be 2.5 Ah Nimhs or RC2000s - much better endurance! This will be fun! Eventually the powerplants - together with the ESCs the Mongo Jr, et cetera, will become part of a Beriev Albatross (Be-40 ?) or Be-200, semilscale flying boat :-)! Tord, Sweden -- If reply difficulties - use [EMAIL PROTECTED] Tord S. Eriksson, Ovralidsg.25:5, S-422 47 Hisings Backa, Sweden RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
Re: [RCSE] Sirius
On Fri 09 Jun, [EMAIL PROTECTED] wrote: In a message dated 6/9/00 7:12:46 AM Eastern Daylight Time, [EMAIL PROTECTED] writes: Needs Sirius' URL, ph., and address, please :-)! Try: www.siriuselectronics.com/ Rich PS, you may not need the / Thanks, everyone who assisted me :-)! Tord, Sweden -- If reply difficulties - use [EMAIL PROTECTED] Tord S. Eriksson, Ovralidsg.25:5, S-422 47 Hisings Backa, Sweden RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
[RCSE] Bring Some Money for stuff at the Midsouth Store
Hi Guys! We will have an area at the Midsouth where vendors like Planes Wings and Things, SoaringStufff, Tim McCann and others have sent inventory 'for sale' at Event pricing. Hinge tape, skegs, Flashy tape, Carbon Horns, Carbon Bell cranks, Nose Skegs, Servo hole flashy tape covers, etc. I am hoping that Volz will be able to send some servos too! But not sure So bring some cash to pick up those 'goodies' you always need right away but have to send away for... :) Gordy RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
