DG800-3

20160824_210436-1Mounted the elevator servo, I found a one in the box that will do nicely. I wanted to use a beefier link to the elevator, but there was not enough space. So a 2 mm version will have to do for now. Maybe change it for 3 mm if I work out how to do it.

I also cut slots into the rudder for hinges, but in hindsight I want to redo them in such a way that there is less visible ‘hinge’  on the outside. The whole rudder needs to be removable, there is a plastic rod for a 1.5mm steel wire built into the rudder, so this is easy.

20160824_210410-1Next task will be to think of a way to make a quick disconnect link to the elevator. I don’t want to use a standard quick-link, they do fail with repeated opening/closing. It has to be simpler, and less fiddly in daytoday use.

Let the mind think about it for a bit, it will find a good solution!

Flying this week is a bit of torture to be honest. 30 C plus and clear blue skies, with a slight haze is not the best weather, simply because it is very hard to see the plane beyond 200 meters altitude. No doubt I will regret saying this soon.

 

 

 

 

DG-800-2

20160820_190758-1Part 1 is a bit back, describing how I did a quick and dirty cockpit frame. Today was the start of more serious stuff, like drilling the holes in the fuse for the all important bit in the middle! First I created a jig that holds and aligns the fuse, and made very, very sure that everything is perfectly level and square. Lasers and camera’s don’t seem to like each other, hence the lack of quality in the pic. I will probably be able to do another one, once the first expoy has hardened. To tricky to touch anything at the moment.

Once the sleeve is in position, I can cut off the outer parts, which will go into the wings. The manufacturer states in the manual they kept the hole in the wing slightly oversized to allow for wiggle room. What slightly worries me, is there anything other than the sleeve in the wing holding things up? Do I need to add something? Glass the wingroot maybe? Time for more research!

 

Logging your flights

Soaring leagueI discovered a fun website the other day, where you can ‘virtually’ compare your achievements with other pilots. Of course I am no match for 6 meter ships, but it is fun. Soaringleague.net is the place to visit. It is a pretty new site, I guess it’s real goal is to log GPS flights, but it works fine for me too!

Tagging the flights is a bit of an adventure yet, but I am sure things will improve over time, since the admin, Pascal is working really hard on it!

BestFlight from 2016-08-20 20-39-20My best flight sofar was a mindbogling, neck hurting flight of altogether 33 minutes. I defenitely need to invest in an easy chair to sit through long flights, standing and looking at the sky does not work!

Up to this point in life I had been concentrating on 10 min fligths, which are not to hard, but stretching things beyond 10 min is hard work when you start from 200 meter or less. (my trusted lady always tell me when I cross 150 meter, so usually I switch off at that altitude and a bit. )

DG800 from Rödel modell

DG-800-cockpitframe-trial1One minute you contemplate building yourself a nice big glider, next time you wake up you have a shed with a few big fish! So far it’s only a 5 meter ASK21 en a 4 meter DG800. Both in need of minor assembly. Since the DG800 is the smaller (and cheaper) one, I am going to try to get that one started first. The DG800 is a Rödel Modell kit, probably something that was made 10-15 years ago. (Haven’t been able to get details yet) However, the ”kit” is in pristine condition. The only giveaway of its age is the papertape holding various bits together.

DG 800 von Rödel
  • Spannweite: 4150 mm (mit Winglets 4400 mm)
  • Länge: 1790 mm
  • Gewicht: ca. 5700 g
  • Profil: E 207
  • Steuerung: Quer, Seite, Höhe, Störklappen, Einziehfahrwerk, Schleppkupplung erstanden.
Die Maschine fliegt an sich sehr gut. Ich bin sie einmal in den Alpen am Hang geflogen und hatte viel Spaß!
Leider habe ich sie bei diesem Erstflug fast verschrottet.
Das Problem ist, dass die DG, wenn du schon sehr langsam bist (z.B. Landeanflug) und dann die Störklappen voll ausfährst, schlagartig abreißt. Ich habe meinen Absturz zufällig auf Video aufgezeichnet und ihn x-mal angesehen. Kollegen von mir haben alle bestätigt, dass die Maschine nicht zu langsam war. Da scheint es wirklich ein kleines Problem zu geben, da der Abriss exakt mit dem Ausfahren der Klappen kommt.
Sobald die Klappen drin sind besteht keinerlei Gefahr und man kann die DG herrlich langsam fliegen.
Auch wenn sie es nicht zugeben, ich glaube das Problem ist bei Rödel bekannt, da ich nach dem Absturz von Rödel folgenden Rat bekam:
“Die Klappen nur halb ausfahren und gut Tiefenruder beimischen”
Kurzum wenn du die Störklappen voll ausfährst mußt du immer auf deine Geschwindigkeit achten.

Die Serie E-205/207/209 hat bei den typischen Modellflug-Re-Zahlen starke laminare Ablöseblasen bei mittleren Geschwindigkeiten, d.h. deutlichen Zusatzwiderstand beim beschleunigten Gleiten.

Die Ablöseblase kann man sichtbar machen, wenn man an einem ruhigen kühlen Abend, bei dem Tau entsteht, einen Flug mit gleichmäßiger Geschwindigkeit macht; man sieht dann nach der Landung einen “Tau-Streifen” auf dem ansosnten trockenen Flügel. Das ist das sog. “Totwasser-Gebiet” der Ablöseblase, in dem sich der Tau am Flügel absetzen kann, obwohl der Flügel eigentlich umströmt ist.

Warum erzähle ich das? Weil es sich gerade beim E-205/207 lohnen wird zu versuchen, die Ablöseblase mit einem Turbulator zu zerstören. Es genügt ein gerader Tape-Streifen (Zierstreifen aus dem Autozubehör), 2 mm breit, 2-3 Lagen übereinander, bei ca. 25 – 30 % der Profiltiefe (kurz vor dem “höchsten Punkt” der Profiloberseite). Der Leistungsgewinn kann spürbar sein, erst recht die (gerade bei Vorbildgetreuen zu beobachtende) Verbesserung des Überziehverhaltens.

Wenn man das Ablöseblasen-Problem löst, sind die Profile E-205/207 gar nicht schlecht; sie haben recht ordentliche Allround-Leistungen.
hab folgendes gefunden:
Das Profil ist für den gleichen Einsatzzweck gedacht wie das E 205, jedoch sollte wegen seiner größeren Dicke die Re-Zahl sicher über 100000 liegen. Das bedeutet Flügeltiefen möglichst über 240 mm. Das E 205 wurde für RC-Segelflugmodelle berechnet, die sowohl langsam in der Thermik kreisen sollen als auch schnell fliegen müssen, ohne daß die Sinkgeschwindigkeit zu groß wird. Es war daher bei seinem Erscheinen ausgezeichnet für die Klasse F3B geeignet. Inzwischen gibt es leistungsfähigere Profile. Auch für den Hangflug ist das Profil gut geeignet, da es bis hinunter zu ca = 0,1 recht niedrigen Widerstand aufweist. Die Polaren wurden im Stuttgarter Windkanal gemessen. Zum Vergleich wurden die theoretischen Polaren mittels des Eppler-Programms errechnet. Weiterhin sind die Ergebnisse der Messungen im Delfter Windkanal und die der Messungen in Princeton von zwei von verschiedenen Erbauern hergestellten Meßmodellen aufgeführt. Die theoretischen Polaren für den Einsatzbereich von HLG im Re-Zahlbereich von 50000 bis 300000 wurden mittels des Winprof-Programms errechnet.

Entwurf: Prof. Eppler
Quelle: MTB 1 und MTB 1/2; Model Builder 5/1982; Soartech Nr. 8 “Airfoils at Low Speeds”; H. Eder “Mehr Leistung mit dem Hand-Launch-Glider”, Verlag für Technik und Handwerk GmbH, Baden-Baden 1996, S. 106.

Clear enough: It’s good enough for a Flatlander!

Anyway, since a challenge is only a challenge if you create on, I decided to try and make a 2016 scale canopy. The original blow-molded plastic afair will be kept for nostalgic reasons). First I wanted to see if my idea sort of works. (My idea: likely something I read somewhere on ye interweb. )

DG-800-cockpitframe-prep1I want to create a well fitting carbon frame. Easiest way to make it well fitting, is to build it on the existing fuse. I stuffed some foam in the inside, and some foam on the outside to create a channel in which to stuff the carbon/epoxy/microballoons. Since it is a trial, it does not yet have to be perfect.

First impressions are: This works! Now I need to order some fresh epoxy, and do it for real. This time I will try to make the frame an even thickness, and offset it a bit to the inside, leaving enough space for the hood.

 

Does not time fly!

674It’s been a while, I must admit. We have the odd bit of summer, interspersed with bouts of autumn and spring and winter. That’s summer for you! Given the general uncertainty of the results of the plans of our minister Dobrin (He who wants to put a ceiling on all model-aircraft activities of 100 meters, so that amazon can deliver their stuff) I have decided for the moment to go gliding. That way I will most certainly be above 100 meters! Once you set the mind to gliding, big ones, all of a sudden the universe throws a lot of them at you. Looking to acquire an 5 meter ship, and possibly 2 pieces 4 meter something. All of them in ‘GFK fuse, and the rest is up to you!’ format. I love it.

So, plans for large biplanes are shelved for now, plans for more F3A-X/Imac planes are shelved. We goes gliding!

I have motorized the PURES a while back, and I must admit that e-PURES makes life easier on the bones. And I get to go up real quick, because I did not have a suitable size motor in the box, I took something that looked about right. On a small 1000 mAh battery it goes up like a homesick angel. Almost as fast as the Orion. And I can repeat that a dozen or so times on one charge. What more do you want?

677Speaking of Orion, it’s getting there too, being tuned in that is. We had a few quiet evenings, which allowed me to tweak CofG without too many disturbances. I am getting to the stage where hands-off circling is happening. Move the battery just a tad more to the front, and we are there. (at least in quiet conditions) This flight was on a Sunday, around 4 in the afternoon. Not bad for one of the first outings!

Noise (again)

I found myself volunteering for a role in the Noisy-committee of the club. We have to abide by the rules, so the first question is ”what are the rules?”

Following is just a collection of bits and pieces, just to get started.

DMFV    (pdf LuftVO)

DAEC

Bocholt

RC-Network

More RC-Network

Laermmessung1a

Excel sheet for calcs (download to your pc)

LMFC

All about audio: audio-stuff

http://www.modellbau-bocholt.de/images/mbg/dokumente/flugplatzordnung_2011.pdf

Paragraph 9: 60 dBa at the nearest house!! Which is rather an important fact. Whivh would translate into 78dB(A) at our site!

http://www.laermorama.ch/m1_akustik/schallpegel_w.html#rechnen

 

Equipment:  anything under 200 Euronen is not worth looking at.. It needs to be a Class 2 certified one.

Laserliner  (various prices, from 160-270, so shop around. ) Can be calibrated!! wich is Very Important!  Of course those calibrators are not cheap: calibrator. Why you need one  (This site has a lot of good ”howto” info.

Wiki: Sound meters

Calibrator

 

We also have a very high back ground noise at the field, caused by the Betuwe Lijn. I have measured in excess of 60 dBA when the train passes on a quit afternoon. The houses that we want to ”protect” are much closer to the railway, so they already suffer from much higher noise then whatever we can add. That’s another story!

These guys did a lot of measurements, so use them to our advantage 😉

https://www.umweltbundesamt.de/sites/default/files/medien/461/publikationen/4005.pdf

Our  location:

http://www.emmerich.de/c125747b002691ea/files/isophonenkarte_elten.pdf/$file/isophonenkarte_elten.pdf?openelement

FlugPlatzGglMaps

 

 

 

 

 

 

 

 

https://www.google.nl/maps/@51.8666569,6.1551396,769m/data=!3m1!1e3

Worth mentioning is that the allowed noise level at this location is 59dBA during daylight hours. (in the LautstärkeGleichenkarte Elten above.)

source: http://www.emmerich.de/de/inhalt/drittes-gleis-und-laermschutz/

So, what is the max level that we are theoretically allowed to produce to reach the 59dBA level?? The distance to the houses is 200 meter (centre of field), therefore a max level is 77dBA is theoretically allowable. This is not to say that we should be lower!   

MaxSound

 

 

 

 

 

 

 

Of course, knowing the level does not help you any further if you want to fix_it. Some kind of octave-filter app is almost a must, but most I-phone/Androids have plenty gadgets to held you find the offending frequencies. (Needless to say, it almost always is the prop/exhaust noise that is the cause of the problem.)

Procedure:  from http://www.mfc-hameln-lachem.de/flugsicherheit/laermmessung

Die Messungen sind unter folgenden Bedingungen durchzuführen:

  • Das Flugmodell ist so zu positionieren, dass sich der im Abschnitt Lärmmesspunkte definierte Bezugspunkt in einer Höhe von 1 m ± 0,1 m über dem Boden befindet und die Flugzeuglängsachse parallel zum Boden verläuft. Das Luftfahrtbundesamt kann in Sonderfällen eine andere Aufstellungsgenehmigen.
  • Zur Vermeidung von Reflexionen dürfen in einem Umkreis von 30 m um das Mikrofon sowie um das Flugmodell keine die Messung beeinflussenden Gegenstände vorhanden sein.
  • Die Lärmmessung muss auf einem kurzgemähten Grasboden erfolgen.
  • Das Flugmodell ist so zu positionieren, dass sich die Flugzeuglängsachse in einem Winkel von 90° ± 30° zur Windrichtung befindet. Die Lärmmessung hat auf der zum Wind abgewandten Seite des Modells zu erfolgen.
  • Die Windgeschwindigkeit darf 5m/sec nicht überschreiten.
  • Die Messung muss an jedem Punkt über einen Zeitraum von mindestens 30 s erfolgen; maßgebend ist der höchste in diesem Zeitraum gemessene Pegel.
  • Die Umgebungstemperatur muss zwischen 10°C und 30° C liegen; keinNiederschlag.
  • Das Umgebungsgeräusch muss mindestens 10 dB(A) unter dem vom Modellerzeugten Geräusch liegen.
  • Die Messung muss bei Vollgas erfolgen. Eine Limitierung von Leistung und Drehzahl, die zur Erfüllung der Lärmschutzforderungen vorgenommen wird, ist nicht erlaubt.
  • Für die Messung muss ein Präzisionsschallpegelmesser nach DIN EN 60651 oder nach DIN EN 60804, in beiden Fällen mindestens Klasse 2, in der Betriebsart „langsam“ („slow“) und im Anzeigemodus „dB(A)“ verwendet werden. Die Kalibrierung der Messanlage mit einem  akustischen Schalldrucknormal zur Überprüfung der Empfindlichkeit der Anlage und zur Ermittlung des Bezugspegels darf nicht länger als zwei Jahre zurückliegen.

Auf unserem Gelände gelten folgende Werte:

  • Kolbenmotor 82 dB (A) >> in our situation it is 78
  • Turbine  90 dB (A)

Also part of the whole thing a flightlog? (automated/RaspberryPi?)

Find a meter with a usb connection to a laptop and use USB extenders. (For safety mostly)

Make a decent test stand

 

 

Out with the old, in with the new..

DSCN0106‘t Is the time of year to indulge in a nice wee present for oneself. Given that I need more exercise, I decided to treat myself to a fresh new DLG. The present Blaster is still flying well, but the new breed of DLG´s is just that, totally different animals. Rather then go for something ”foreign”, I decided to call Alex Hoekstra from Tweagle fame, to see if could make me a Xmas present. Lucky for me, the answer was yes. So a quick trip was organised ”up north” and soon afterwards I was able to take posession of a shiny black DLG. First thing you notice is: It weighs nothing! At home I quickly located my scales to find how much nothing is. Wing is 104 grams. (This is the D-box version), El/Ru together 10 gr. Fuse is 38 gr. All added up, we are talking 152 grams for bare carbon! At the moment, the fully assembled glider RTF sits at 230 gr on the scales.

DSCN0102I have 4 KST-08‘s fitted, a Jeti 5 channel RX, a small 2 cell Lipo from ”way long ago”, and my Openaltimeter found a place too.

I updated my Multiplex Cockpit to Jeti, but even though the setup works flawlessly, I might start saving for a true Jeti. Setting up the Cockpit is just so tedious compared to the a proper Jeti system.

Once I do some fine tuning I will probable loose a few more grams. (Wiring is bulky at present, I can also loose the connectors on the receiver, might still change the guitarstrings to a bit of kevlar, we´ll see.

Building a plane like this is not to be undertaken if you have never built something high tech like this. Do take you time planning your build. Everything is just strong enough to do the job, it is not designed to be bashed about in your typical overfilled hobby hideout! Look on RCG for tips. (or RC-Networks).

One thing to note, is that the weight mentioned on the website, is probably ReadyToFly, not bare carbon!

I do not have a lot of build pics, it turns out that fotographing carbon is difficult. Tomorrow we have a midwinter-spring, temps are predicted to hit at least 14C, good enough for a spin I would say. This will be the second outing, the first spins I made 2 days ago in 8 m/s wind, not really that good for a maiden flight. All I can say it went up like the proverbial homesick angel! The third toss showed a respectable 30 meters on the Altimeter, and this was just a gently flip of the wrist!

Merry Xmas everybody, and a Happy NewYear!

Winter is here again, time for an update

db_Skybolt_Andre_5571It all of a sudden feels cold and miserable out there, so this is a good time to start a new project. For many a year I have wanted to build a nice biplane. The thoughts have gone from a Waco to a Starduster, or Acroduster. I finally settled on a Skybolt. The main reason for this choice at the moment is that I do have a set of Wendell Hostetler drawings, and I have located a live example not too far from home. Those two things should be enough to get started. The Hostettler plans says it has a 77¨ span, (194 cm in real money) 170cm long. This makes it transportable. Recommended engine says ´Quadra´(Don´t think you needed to spell out the size of the engine in 1997, there was only one size.), all up weight supposed to be 10 kg. Prop something 20×6. Of course this all sounds as if my trusty MVVS58 will do very nicely indeed. I even found an engine template stuck to the drawing already 😉

I have been tossing this around for a while, on the one hand contemplating making a new 2015 version of the plans, on the other hand, just start building. If you like it, you can build a round version with all the mods you think you need. And of course, building it the original way from the plan is in itself a ´historic´ job.

There appears to be a large amount of info available on ye interweb, so I will have to weed through all that too.

Anyway, with the mind set into gear, it is now a proper project. First some links I found for inspiration:

I probably do the smart thing and make a mockup of the engine/cowling/exhaust, just to see if it will all fit. The Quadra used to have a NoExhaust, I won´t get away with that! First thoughts are to try and hide a custom exhaust somewhere on the inside of the fuse.

Just spotted this add on Barnstormers.com,  and  this bit: Aeroclub NRW.  I hope they are not selling this one!

more to come..

I built myself a 3D-printer

_20150722_160108
..after maiden fligth at Herwen.

..and a whole new world opens. This has been a project, both rewarding and frustrating. but I have learned a lot, and at present I am able to make quite acceptable printed parts. Of course this whole thing of 3D printed parts means you have to learn how to fit those parts into the modelling universe. Over the years you have build up a good feeling of material properties that work in different scenarios. This plastic stuff requires you to learn new tricks. On the one hand you seem to be able to make very complicated parts, but on the other, you find that the materials properties degrade very fast with higher temperatures. But it will be great to make little bits and pieces, as you need them for traditional moddeling applications.

IMG_20150704_211925988
might as well print a few spares

To start off I build a quadcopter.  This is a PEON230 which I found on thingiverse.com. Seems a rather straightforward project.  I choose to use a NAZE32 as the controller, running Cleanflight Kamikaze software. (As in the latest stuff, guaranteed to have bugs 😉

So far I have had 2 destructive crashes, both from 30 meters high. 1st one happened on the first flight (of course) because I lost orientation. The quad is rather small and at 100 meters it was hard to see which way it went. Rather then ending in the drink, I thought it safer kill throttle. NotGood when you fly a quad. Ah well, one has to learn!  I have since added some LEDS from a led-torch to help me see which way we go.

_20150805_201751
take a selfie with your quad.
IMG_20150801_194455029
..added some headlights

Damage was actually minor, the top plate where the battery is mounted, cracked. I had printed it with 20% fill, obviously not enough! Since then I have had approx 5 hours airtime, and no major mishaps until last Sunday. I had been messing with my PID settings, and I thought is was a good idea to increase signal-loss RPM. supposed to prevent a fly-away when you loose signal. Somehow the opposite happened, it took off like a homesick angel, until I recovered from my shock. By then it was going towards the water, and much as I like a nice swim, I did not fancy taking any chances. So I chopped the throttle, this time knowing I was asking for a solid crash. However, the damage was again minor. Both the upper and lower support plates were cracked, (by the weight of the battery) but the arms were all ok, and no other damage was done.

The great thing about 3D printed parts is, is something breaks, you just fire up the printer and you get a fresh part! So after some minor disassembly I have now copter #2 in the air, looks the same as #1.

I’ve also started the construction of a tri-copter, looks like that is mechanically a bit more of a challenge. As always, in the beginning (the first few projects) you use what is there, then you start to modify the designs, then you make your own. The Brocopter (google Thingiverse) uses a servo to rotate the rear arm, the construction to rotate it is not exactly something I would trust, so this is the first part that needs redesigning.

_20150805_213902
and a tri-copter in the making.

RES in the making too

IMG_20150517_182205872As a first build in our new residence I got myself a few RES kits from Josef Gergetz. RES stands for Rudder Elevator and Spoiler. It´s a class of glider measuring 2 meters span, and it is very restricted as to the materials and construction used. It is intended as a low cost platform for lots of fun.

specs are:

Name: PURES V2
SPW: 1990 mm
Länge: 1120 mm
Profil: AG 35 – AG 36 Strak (Mark Drela)
Flächeninhalt: 35,7 dm²
Abfluggewicht: 670 g
Flächenbelastung: ca. 19 g/dm²
Steuerung: V-Ltw: Seitenruder, Höhenruder, Bremsklappe
EWD: 0,7°
Schwerpunkt: 75 – 80 mm

There is a long article on RC-Networks, you can go and look at the pictures there and here.

We finally have a maiden! during the first fligths there was a mild westerly blowing from the lake. This usually goes together with turbulent air caused by the trees that line the shore. So lots of bumps are expected 😉

After a few tosses,  I felt a bit more gravity was needed in the nose, and feeling brave, decided to try my bungee. This one was originally intended for the little DS-Birdie, but who cares. First launches were made with approx 30 meters rope, enough to get up and see what happens.

Things were a bit confusing at first. I had decided to slave my aileron stick to the rudder (dual control really) since the standard recipe sets everything up on rudder/elevator. I feel more comfortable having my directional control right, and elevator left. However, I did not check if wiggling my right stick did produce the same effect as wiggling the left stick. Anyway, you figure out pretty quick when things do not turn in the direction you anticipate. No harm was done to plane or pilot, so after teaching the tranny to move surfaces the same direction on both sticks, more fun was had.

Due to the freshening wind I could not really do much more then hang in there. Adding enough rope to span the entire field gets me up to approx 40-50 meters. I am not sure yet what the correct way to get rid of the rope is once you are at altitude. My feeling is that I should fly past the vertical, at wich point I should have reached maximum height, give a bit of down to release the tension on the wire to let go, and off to blue skies above. Due to the strongish wind I have the feeling I was more or less flying like a kite, untill pushing down pretty hard to release.  Anyway, we will learn this trick too.

After lunch and a quick dash into the shed, I made a few bits of ballast. The main wingspar is a hollow 10 mm carbon tube, so it is easy to simply insert something. I had a few sizes of alu tube, which give me 60, 100 and 150 grams of ballast. (The plane RTF is 450 gram) . With the added weight (150 gram) the performance improved, I could fly against the wind and even make a few turns!

I just noticed that the stated RTF weight is 670 gram. Mine weighs RTF 450-ish. No wonder I needed to add ballast!! I must have forgotten to add some major parts to end up that low?? And I was contemplating making it even lighter! (Like get rid of the steel wires/tubing to drive the v-tail,  use ligther servo’s etc. I now have 60 gram ballast up front, I can probably reduce the RTF by that much if I try hard.

Next time I hopefully will be able to try in more favorable conditions, after all this is a glider for these long windless summer evenings 😉

Todo: probably a good idea to stick this one on the same tranny as my DLG, it is a bit of overkill to use a Jeti tx for this. I will also move my little altimeter/vario here, to see what happens during launch.

IMG_20150517_094324257