Archived Items from the Research page......
Recommended reading: The August issue of RCModeler magazine has published the basics of the tunnel testing mentioned in our techincal section. Click here for the details.
I think you will enjoy a visit with Phil Ploof and follow his facinating experiments involving tilt control of a DUAL rotor model.... ! Click here
Karl Sichelschmidt sends this new idea from Germany....
Details as soon as I can find where I hid them... :-)
Emilio Cabezas (Our Spanish GyroNut) wants to mention that he and a fellow G-Nut in Spain have experimented and found that it is not really necessary to restrict the "up flap" in the rotor blade as much as previously thought... In fact they have found that additional "up flap" (versus the standard 20+ degrees we have been using for the past few years) aids in obtaining a faster entry into "Autorotation", as long as the blades are swung forward initially such as with the "Delta" configuration. Emilio is stressing that the main reason for using these two features is to make R.O.G. takeoffs feasible without the need for a prerotation system. Faster rotor spin-up is mainly provided by delta hinge action while autogyro roll over towards the retreating blade is precluded by removing the flapping stops (or setting then at a much higher angle) so that the blades cannot hit them during takeoff, when rotor speed is still
too low.
Gyronut Bill Friedlander has built an excellent version of Paul Stahlhuth`s "Virtual Gimbal" rotor head.... and installed it on his Kombat Kopter as an experiment. Bill sent these photos showing his handiwork. Flight tests will probably not be made until Wisconsin thaws out and warms up a bit after the long winter..... You may click on either photo below (31K & 37K) for a larger/closer view.
Note: The Virtual Gimbal rotor system has not been sucessfully flight tested as yet.... it is hoped that a positive test will be completed this summer (2001)
Jim B`s "PT-Gyro" (pusher/tractor) Click here for the latest information on this experimental model... ... .
You may also click on the photo on the right for a larger view.....>>>
Its been asked.... "What ever happened to the "G-Whiz"?
Well.. . actually it has been flying very well this past summer. It initially floundered around last spring with an inadequate power source. After a few minor changes, plus a change to a lower aspect rotor blade and an upgrade to a more powerful electric motor, it is now a sweet flying small gyro with a 33" rotor .
It is expected that plans will be offered later this winter.... for this easy to build, easy to fly model. You may click on the photo for a closer view of the current flying version.
Les Garber and Bill Friedlander have completed an extensive wind tunnel testing of several rotor blade airfoil designs.
They hope to have the report published in a model magazine, however in the meatime I will attempt to cover some of the highpoints of the report for those of you who would be interested. This detailed report seems to confirm many of the findings we have come up with through many years of experimentation/trial and error, however there are a few surprises in regard to the performance of various airfoils. Click here For the current summary...
Technical comment:
Years of experience have demonstrated to several of us that the rotor blades on these models, with their relatively slow RPM, do not really have to be balanced chordwise! It has been found that as long as the blades are equal in weight, and the rotor is spin balanced, blades do not demonstrate any problems such as tuck-under, flutter, etc.
The critical thing is to spin balance the rotor, and this is much easier to accomplish if you build the blades from the same piece of material and keep them equal in weight to each other. Mark each "matched" set of blades so that you will always use them together.
For those of you into electrics.... there`s a page on the AstroFlight website you should read over: Frequently asked questions It certainly can be helpful for the beginner. While naturally the emphasis on the page is on the Astro motors, for airplanes you can basically consider a strong speed 400 as nearly equal to a glow .10 motor. However in regard to powering the high drag model Autogyros, a speed 400 is about equal to .049... in glow power.
Electrics? Visit....the Ezone....
We have just received some great info from JoJo Chaulet (France) in regard to his recent success with
a pusher, electric model The file on.Jo Jo`s model can be seen by clicking here. ..
Balsa dust and Rotor blades...
Want to see em? Click here.. or on the photo.
Brian Gibbs, of the United Kingdom, continues to prepare his 1 / 3 scale Bensen model for untethered flight..... Towing speeds have reached 40 mph, and adjustments are being completed to fully stabilize the model for eventual untethered R/C flight. Click on Bensen for the latest details as of August 13th....
Les Prevost, Channel Islands, England,
sends these photos (below) of his latest experimental model... You may click on the photos for a closer view. more details later....
From time to time it becomes necessary to remove items from this page simply because the work on the model and/or item is not being completed timely, and the need to make room for something new and refreshing.
When you find an item of previous interest is missing please check the new technical research "ARCHIVE" page.
British Electric Flight Association web pages....
What happens when you take a very stable model autogyro such as the original "Suitcase Minnie" in the left photo, and switch the tail around? If the vertical fin is moved well forward such as shown in the center photo, and reshape it enough just to avoid blade strikes, will it fly as well as the original configuration? Or will it even fly at all?
What if we move the horizontal stabilizer (photo on the right) forward and leave the fin in place? Again, will it fly as well? Or even fly at all?
One answer is obvious.... having a photo of the second experiment after testing the first must mean that moving the fin forward worked.... right? Yes. And any difference in performance and control was hardly noticeable. Now as for moving the horizontal stabilizer forward, that was a different situation! I still have the model intact, and undamaged, but am very fortunate....
it was a wild flight. The fact that Suitcase Minnie is so stable and flyable in the first place enabled me to complete a circuit and land. Lets just say that moving the large stab so far forward was a near disaster. [jb]
Meet two versions of the "G-Whiz"... A new electric model . by Jim Baxter. The model on the left weighs 280 gms (10 ounces) has a rotor just under 30 inches, and is powered with a POT-3 (aproximately a 280) .... The one on the far right weighs 480 gms (17 ounces) and sports a 32 inch rotor. The center photo is of the lighter (left) one, with a set of JoJo Chaulet`s indoor blades installed. Both are newly completed (Jan 2000) and no test flights have been completed as yet due to the winter weather. Both are variants in a series of small / lightweight autogyros being designed at this time.... An indoor version of less than 7 ounces (200 gms) and a pusher version in the area of 15 or less ounces (425 gms) are on paper at this time. Click on either photo for a larger view....
Note: Spring 2000, this long wet winter has prevented any decent flying attempts, except for a couple 5 second rotor flight tests and the built-up blades (ala.. Chaulet) demonstrated exceptional lift. I`m anxious to see if this actually proves out when full flight experiments are completed.
Update July 2000: The larger of the two models is now flying very well following an upgrading of the motor and a few minor modifications. It is expected that the smaller one will eventually be flying with or without the slow / Chaulet blades... with an upgrade of the motor. These electric models are extremely critical of power and weight.
Check out Paul Stahlhuth`s brilliant and inovative
"Virtual Gimbal" rotor system! Paul welcomes your personal comments....
Paul Stahlhuth`s new experimental Dual teeterbar DC "DERVISH"
Update: January 2000... Paul was unsuccessful in his first attempt. The model `looped` on launch. Some pitch adjustments are being completed and the launch method/technique is being changed.... (jb)
This model sports a 50" rotor (soon to be replaced with a 45"), weighs 58 ounces (giving it a nice 4.25 disk loading), is powered by a Magnum .28XL, and utilizes DC (direct servo control) plus rudder and Paul has installed a way of trimming in elevation control.
Click on a photo for a closer view.....
To further comment on Paul`s efforts, he has devised a way to balance rotors by adjusting individual blades to identical weights and CG locations before mounting on a delta 3 hub. He also has an idea that he calls a "Virtual Gimbal" , that is the instantaneous center of pitch and roll motions was above the actual gimbal mechanisms and remained at the same plane as the CG of the rotor system, independent of of the head tilting. This is an attempt to reduce rotor vibration and aerodynamic loads being transferred to the overhead control stick.
Editorial note: Please refer any questions rearding this directly to Paul at:
phsjes@innercite.com
When you are ready to get real serious about small light models.......
This is one of the smallest (perhaps the smallest?)... receivers in the world. The Sky Hooks & Rigging SHR-RX72 Pro. Believe it or not, this thing is the size of a 1/8" thick postage stamp! It is FM, has 5 channels, and weighs a mere 2 GRAMS! You ought to tackle the job of soldering servos or connectors to it ! It`s a bit difficult and requires a very pin-point soldering iron and a magnifier (for we older gents) . The range is listed as 1,000' (or about 300 meters). However I noted it to lose contact at about 400 feet, which matches a few comments I have read elsewhere on the Internet. Additionally mine tends to "glich" similar to a micro-second loss of power about every 20 seconds, regardless of antennae orientation. This may be abnormal and I plan to have the builder check it out. Note in the left photo a 10" propellor, the 17 x 17 (mm) motor and the receiver, along with a US 10 cent 'dime'.. Yes... for those of you wondering, it is primarily designed for the indoor model, however I intend to actually use it outdoors also.
The photo below shows that I elected to installed three connectors with one being used as the power lead.
Update on the progress of Willem`s model shown below. He is awaiting new matched blades and plans to install a 3 blade flapping rotor and a hoped for overall weight of 85 grams. (that`s only 3 ounces!) If / when this model flys we will post it here...
Here is a marvelous little 18.5" rotor, DC teeterbar electric that only weighs 3.9 ounces!
Will it fly? Well...... not successfully yet says the designer, builder, Willem Bravenboer from Belgium.
The WES Dc 5 - 2.4 with 6.7:1 reduction, turning an 8/5 carbon prop is not quite enough power it appears.
NOTE:
I have not heard of any successful flights with this model since this information was originally received a few months ago...(1999) so this
project remains in limbo until further word is received.....
You may click on the photo for a larger view....
In regard to Stewart Russell`s 1/2a .049 model shown here , Stew is working on the plans for it
and we`ll let you know as soon as they are available. It is a dc (direct servo-rotor) controlled model, powered with
a Cox TD .049.
If you seem to note a "sorta Cierva" look in these little jewels.... you are correct...
Super simple, lightweight, easy to build, functionally superb... a dual axis dc head, with a rotor hub using thin fiberglass, or
thin polypropylene.
The ones shown here are for 1/2A to .15 model size, and flight tests have shown lots of promise.
The idea/design can be adapted to larger models. Let me know if you may be interested in plans for these and I might just produce a few...
Return to the Research Page
To the Technical Menu
items added/transferred: 01-05-03..jb