|MH45||1.65||9.85||+0.0070||-0.27°||F3B, F3F, Slope Soaring|
|MH45-8%||1.65||8.00||+0.0070||-0.27°||Do not use!|
|MH60||1.76||10.08||+0.0030||-0.31°||F3B, F3F, Slope|
|MH60-12%||1.76||12.00||+0.0030||-0.31°||Open class, Combat|
|RS 004||1.64||9.00||-0.0416||-1.87°||F3B, Allround|
|TL54||2.41||9.99||-0.0171||-1.20 °||F3B, F3F, F5B|
|TL55||1.90||9.44||-0.0052||-0.68 °||F3B, F3F|
|TL56||1.40||8.96||+0.0072||-0.144||Aerobatics, Turbine, EDF|
|SD7003||1.46||8.51||-0.0430||-1.76°||Thermal Soaring, Allround|
|S5010||2.20||9.83||+0.0080||-0.52°||F3B, F3F, F5B, Allround|
|S5010-8%||2.20||8.00||+0.0080||-0.52°||F3B, F3F, F5B, Slope|
|S5020||2.62||8.40||+0.0080||-0.70°||F5B, F3B, Allround|
|S5020-8%||2.62||8.00||+0.0080||-0.70°||F5B, F3B, Allround|
|HS 520||2.13||8.82||+0.0041||-0.64 °||F5D, F3F|
|HS 522||2.01||8.67||-0,0050||-0.84 °||F5D, F5B, F3F?|
|EH 1.5/9||1.50||9.00||+0.0000||-0.51 °||Aerobatics, Turbine, EDF Ex: F3B|
|EH 2.0/10.0||2.00||10.07||+0.0000||-0.68°||Ex: F3B, Open Class|
|Sipkill 1.7/10||1.70||9.93||-0.0060||-0.76°||EPP Combat (Zagi)|
|HS 130||1,678||9,652||+0,0157||-0,09°||Slope Soaring, DS|
|JWL-065||1,687||7,96||+0,0298||+0,30°||Allround, Slope Soaring|
|CJ-5||2.33||9.30||+0.0200||-0.10°||Ex: Plank, Thermal Soaring|
|CJ-25²09||2.50||9.50||+0.0270||-0.13°||Ex: Plank, Thermal Soaring|
|HS 2.0/8.0||2.00||8.00||+0.0120||-0.33°||Plank, Slope|
Ex: Outdated, you should not use these airfoils in high performance
S: Flying wing airfoils are characterized as reflexed, in German called: "S-Schlagairfoile"
F: Airfoils developed for the application of flaps or working well with
new or edited airfoil
Oops?! No, not a mistake of mine just the latest trend in Tailless scene. Tailless??? No, C-Wings are no more Tailless I think (see Projekt 42!). It is allowed to use C-Wings in Flying Wing contests but from aerodynamic point of view these upper wing parts are functional seperated horizontal stabilizer.
In the early 70s the "Spezi" or "Wehmann" concept using little wings outside the winglets is just the same principle: functional seperate parts for horizontal stabilization. This is my personal opinion, you can surely discuss about this item. C-Wing is some kind of hybride between h-stab and tailless but a very strange one!
But whether Tailless or not is not really important. It is a new design and perhaps it helps to analyze some other problems. The strange central rudder designs in the early 90s (e.g. E.T.) were necessary to get rid of the "propeller" problem during highstart. The fuselages had been longer than the one of h-stabs!!! This way doesn't make any sense but was very helpful to analyze Winglet effects!
So never damn a concept just because it is a design philosophy problem like C-Wing! Let's see if they get rid of their handling problem. Nowadays you can fly with them around the world. But don't try to fly a turn or something like that. The C-Wing tries to keep his direction in a manner that is unbelievable. No advantage without disadvantagee, the old game.
Conclusion: Still something for immortal optimists!
The maximum lift coefficient (cl) is somewhat small. This causes some disadvantages especially during high start compared to newer high cambered designs. See MH-32 trend...
To achieve the best performance small wingloading is recommended! CO5 is a design like this, around 25-30g/dm² you get maximum performance. At higher wingloadings there is a lack in performance (sinking rate) in comparison to MH60 or S5010.
But inspite of the needed low wingloading for best performance the speed performance is quite impressive! So if you think this section is just something for light thermal soarers, definitely not! The disadvantage of these MH-45 concepts is more or less somewhat low aspect ratio and due to this lack in gliding performance. Thermal and speed performance is quite good. If you ever met a CO5 in a small, tight thermal you know that your model is damn shit. But leaving this thermal you know that CO5 is damn shit! Ok?!
Conclusion: For lightweight swept wings having low aspect ratio.
Optional airfoil for Zagi, also see Sipkill.
Somewhat faster than the original 45er, but a lack of clmax. Therefore stall is coming like a shark during high speed turns for example. A very fine training for your flying skills but no insurance for a long life...
It has not been one of my best ideas modifying the airfoil this way. To get an idea of the influences: the lack of camber is compensated by higher thickness. Lower thickness together with higher camber works well too. But a lack of camber and thickness causes trouble on this specific kind of reflexed airfoils. E.g. 1,5/10 (camber%/thickness%) and 2,5/8 works well too. But 1,5/8,0 can cause trouble!
Conclusion: Bad idea!
The LOGO Team often flew this section. You can believe me: they were damn good! It was no fun to fly against these guys that time! Surely a fine design of Martin Hepperle, perhaps somewhat better than the MH45. This difference seems to be more induced by the resulting Tailless design than by the airfoil itself. The pitching moment (cm, cm0.25, cm25, cm1/4 however called) of the MH60 is lower than that of MH45. So for same basic cl you need more wing washout when using MH60. This causes more differences in handling than the airfoil itself.
Attention: Some pilots have had trouble with a marginly negative pitching moment! E.g. LOGO Team have had a model (HOLON) with a design cl around 0.1 (bad idea!!!). Stabile flight in clean wing configuration with MH60 had been upside down!!!
Thorsten Lutz has developed the airfoil series TL54, TL55 and TL56 using Eppler Code. The airfoile series is already some years old, but has been hardly known in tailless scene. The difficult relations concerning stall behaviour on Tailless using different airfoils does normally not concern to the requirements of competition RC-Models. The potential benefite using different airfoils is minimal due to the flight behavior. Often it is so worse that just Tailless speed models use different airfoils. But even F5D designs normally use just one airfoil because cd optimization means reducing cd where cl requirement is small. And where is cl small? @Wingtip. What means stall @wingtip? Ok, the influence of reduced cd on stall behavior should be quite clear now. RC pilots normally don't like digging their models...
Therefore we do not talk about teamwork performance of this TL series, just about possible application using one airfoil for wingdesign.
The main attention during design phasis aimed for long laminar run on airfoil lower surface at high speed (cl=0.1 .. 0.0). This is the basis to achieve low airfoil drag at highspeed. Inspite of 2,41% camber TL54 reached this design goal. We have here an airfoil that provides a lot of lift (clmax) despite very low drag at low CL! The direct consequence is an extremely wide area of application! Now the F3B designer should become poorely soundproofed among us, because the secret of the MH-32 is reasonable just this...
Let's talk about something else: the zero lift moment coefficient (cm0)
is around cm0 =-0.017 and this is unstable. Some years ago (4mm washout
and cm0=0 design airman )
we didn't have the counsciousness to use cm0<0 sections because of
high washout. Later on we became more self-confident and noticed that
a lot of washout does not hurt. The experience using SD7003 and RS004A
showed that it works, inspite of cm0 =-0.04. In addition to this there
is something else: Some of these models had problems around pitch axis
(elevator). Pilots complained about stability problems, some designs
of this period had been unstabile.
And just this is an interesting point: I do not know F3B-Tailless designs which aim the middle between these before mentioned design concepts: cm0 =-0.02. Which does not or just partially work with cm0 =-0.04, could work with cm0 =-0.02!!! And in my opinion TL54 is just the right choice for this!
(Don't talk about C Wings! This is a hidden h-stab!!!)
The only disadvabtage of TL54 is the thickness of about 10% from my point of view. Light models might fly a little bit restless in gusty conditions. I would advise you to reduce thickness around 9%. Same time you should decamber the TL54 to get the before mentioned long laminar run on lower surface inspite of reduced thickness.
For further details, please, read TL54. In my opinion TL55 is unsuitable for high-stretched designs having high wing load. Models with variable flight weight should use TL54, as it offers a clearly better gliding, highstart and speed turn performance especially at high wing load.
TL-55 is not suitable for F3F because upper surface laminar run is not as long as on other airfoils. The MH-60 might be here better choice. In negative flight figures (upside down) the TL55 will be much better than the usual suspicious . Therefore, as section for the ZAGI it would be certainly interesting, beside Sipkill, a special section for Foamies.
Conclusion: For medium-sized Allrounder certainly a good choice, for performance and competition models use TL54...
One of the newer creations for Swept Wings. Design by Sielemann/Hans-Jürgen Unverferth. Due to negative pitch moment a lot of washout is needed. I suppose same handling characteristics (something strange!) as tailless designs using SD7003.
This RS 004A has been used on CO8 and this model have had handling problems they never get rid of (Source: Sielemann). This was probably induced by the airfoil. They never managed their problems in flight stability around pitch axis. For a first attempt in low-cm pitch down airfoils it is not a good choice I think. SD7003 is a better choice to do this for the first time I guess.
I suppose that the real cm is lower than calculated. Having too low cm in design and later on correcting this by using Flaps/Elevon is always extremely critical!!! Often you never get rid of stability problems around pitch axis. I know this problem from several designs of myself!
Why this effect occurs I cannot say. I suppose that a frequency effect induced by laminar separation bubbles when deflecting flaps is responsible for this because some models managed their problems by using trips. But in most cases nothing was helpful except taking a chainsaw and cut that model in very little pieces for a final fire...
Please note that most modern Tailless projects use cm<<0 sections.
The advantage is rising the gliding performance, the disadvantage is handling
around pitch axis! Speed and sinking rate are more or less the same as
on cm=0 concepts. Most projects never get rid of their pitch axis problems!
Rising gliding performance is only one part...
So general for beginner in Tailless design I would recommend cm=0 concepts because they are very well tested and uncritical. Later on you can try these cm<<0 sections.
Conclusion: This way of design works or works not! Unfortunately there is no criteria during design phase to indicate if there are these before mentioned problems.
The design of these Tailless is similar to RS004. Same difficulties. Performance is quite well only handling characteristic is something strange. Gliding sometimes feels like swimming, not flying "in" the air, just "on" the air. Yes, really strange especially using low flight stability (CG back).
So try this cm0<0 concept or forget it. For thermal conditions this is surely one of the best or even the best Tailless design concept I have ever seen. Allround conditions seems to recommend less negative cm than SD7003 or RS004 have.
Quite well but something too thick. Due to this it is something gust sensitive. Direct flight comparison between S5010 and S5010/8% showed this on a quite heavy day. Wind around 20-30kts, gusts up to 40kts. The model with the origin airfoil had some problems in holding course and there was an interesting effect on height axis: when hard gusts came in, the model swang for 1-2s! The thinner airfoil in same conditions (parallel runs) was faster and did not show this swinging. Both models speed was around 100-150kts, quite fast. But these are the conditions in competitions where this can decide about victory or not. This was the final reason for using the thinned airfoil for my F5B contest model. In the meantime I know that a thickness about 9% does not cause these problems on this kind of model.
Never forget that these experiences are tight related to the test model
HS40 (F5B): Electric Engine 1.7kW (2.1hp), climb rate 50m/s (60-70kts),
wing loading 75g/dm² FAI (=24,58oz/ft²) and weight around 2kg
(4 lbs). That means: For a F3B or allround tailless design this has not
much to say. But this example shows that you can run into trouble in flight
dynamic induced by airfoil beside cl/cd and velocity distribution diagrams.
Ok?! Not more! Ok, back to the unmodified airfoil: clmax is high enough,
high start works well. Testwing for this airfoil had been HS40V1 "Sexxy".
(This airfoil is also known as S 5010-098-86)
Does not have the before mentioned problems in gust sensivity. It is a quick and very agil airfoil, some people would say nervous. I like this but it is not everybodys thing. Than use the S5010-9% and it is ok. Tailless in F5B-600 can use this section. For F5B it could be a good choice. But therefore I recommend a S5010 (2,4/8,5) because of high speed turn radius. Back to S5010-8%: in all weather conditions it works well. For slope soaring it is perhaps one of the best allround sections I have ever seen.
MH45 is better at lower wing loadings (15-40g/dm² = 4,9-13,1oz/ft²), S5010-8% around 20-80g/dm², S5010 35-100g/dm², S5020 is a good choice for 25-90g/dm². Just to get an idea what you can do with these sections in allround conditions. This data given is not to discuss about 1 or 2g/dm² where a section works or not. But for small up to midsize models (1-4m) this could be helpful. No, I don't want to talk about Rn-numbers, because handling characteristics have much more to do with model's dynamic behaviour and its airfoil than actual Rn. So I think it is more helpful for you to talk about wing loadings...
For handy models (1,5-2,5m) this section works well up to 80g/dm². I used this on the HS33V5 "Chicane", this was a damn good model, one of the best I have ever designed. It was fast, smooth handling characteristics, tight speed turns and had a good thermal performance. At this time the HS33V5 was the very best existing F5B/10 model. Sorry, I always try to be realistic, but this combination of low weight (1,7kg), 10 cells and 1kW engine power was really a sexy combination. Now you know, where the name of HS40 "Sexxy" the following development come from.
Very fine airfoil unfortunately too high cambered for F5B. This means heaving disadvantages against S5010-080-86 when flying at high gliding speed (cl<0.3). For wings without winglets almost acceptable but not with. Decambering to 2.4% could be helpful. The reason for this behaviour is the drag increase beneath cl=0,2 of the origin S5020.
But in thermal soaring you will kill these h-stab guys in F5B! FAI 75g/dm² (=24,58oz/ft²) is nothing to think about, this airfoil is a thermal soarer! Up to 90g/dm² (=29,5oz/ft²) it works damn well.
For a F3B Tailless this section should be proper too, regarding MH32 e.g. My full moulded F5B project HS40 "Sexxy" uses the unmodified S5020 and even nowadays after plenty of years with this design I am surprised how great this model runs! You cannot hear this model until it passes you with 200km/h or whatever with a cool whispering sound and then disappears almost silent in the sky. The reason for this? Reflexed camber means having thin boundary layer and so these kind of airfoil is silent especially at high speed. This behaviour is actually used for the most uptodate Wind-Turbines to reduce the acoustic noise.
No, F3F pilots should choose some other section like MH60 or so, the S5020 is not the right choice. But for Tailless that have higher wingloading and allround requirements this section is absolutly perfect!
The low wing loading tests on this section are actual (nowadays) going into the next phase. In the next month there will be some more experience on this except my own! One of these projects is that of Arne.
There is a hint in some airfoil databases that you should use this section only for Tailless with high wingloading. This is damn shit! There is no Rn problem and velocity distribution says exactly the same: nothing to think about!
(This airfoil is also known as S5020-084-86)
Don't do this, use the origin S5020. It is just a thinned (8,0%) version of S5020. No disadvantages in handling I think. But the laminar bump ends earlier so the S5020 is something faster although the 8,0% is thinner!!! I didn't think about this point during design phasis. My HS40V2 "Sexxy" is build with this section. This model had been lost during the first test campagne because of RC problems.
So I cannot say, if there is a large difference between S5020 and S5020-8,0%. I think using the unmodified S5020 is the best idea!
One of the most popular airfoils for swept wings due to low drag (speed) and very low Re-Numbers you need. Outboard chord has been tested until 70mm (!), 100mm is more common. This airfoil was designed for speed wings too, but today you find even HLG tailless using this airfoil.
EH 2,0/10,0 (EH series)
Especially the EH2.0/10.0 has had such an influence that swept wings with 2.4...3.0m had a bad handling and performance that one day I took my daddy's chainsaw to check out how much time it takes to cut the fat carbon fibre spar (max load: 40g) into pieces: five seconds...
Annotation about the history: These airfoil series had been designed
by John Yost. He took the E228 drop and combined this with an old Horten
camber line. This was the birth of EH-Series (Eppler Horten).
Conclusion: This use of this section is not recommended!
What is the design goal of this section? Just to be better than ZAGI section!!! kill is the hint... Where does the rest of the name come from? Si is abb. for my nick Siggi, Peter K (pk) is a crazy EPP combat guy who asked me to design this.
The Sipkill 1,7/10 is for Combat and nothing else! Crashproof mechanical design is one thing that has nothing to do with aerodynamics, more with fat trailing edges and so on. So Sipkill is surely not the best design for high performance but a good combination of mechanical and aerodynamic requirements! And as I guess surely better than ZAGI-10%. Due to the fact that most "modern" Combat designs her in Europe use C-Fibre-Spars means reducing thickness causes no structural disadvantages. Less than 10% is not crashproof enough I think but we will test it.
Several modellers asked me if I could design something new for Combat tailless. During last weeks I got several Emails asking me when I would publish this new section! I always said: Not before I tested it myself! Ok, they persuade me not to wait so long and here it is! And it was the right choice: Sipkill is fairly (much) better than original Zagi. Especial gliding and speed turn performance is the improvement. S5010 or MH60 reduce sinking rate, but upside down and bank rotation is surely not as well as MH45 and Sipkill. MH45 and Sipkill seems to be the overall best airfoils for Zagi. These sections have alomost same performance as you can see in the polar sheet. Sipkill just have thicker trailing edge due to foam building technologie.
If anybody asks me about the negative pitching moment (cm0<0) do not Email me, just think about Trailing Edges/Elevons made of 4mm Balsa like ZAGI. Yes, we understand each other I guess: doesn't matter, really not! For calculations on a Combat tailless assume pitch moment coefficient cm0=+0.01, because most pilots adjust their flaps in that manner.
Conclusion: For Foamies like Zagi and here much better than original
airfoil without any disadvantages in handling. Due to 10% thickness you
might use a carbon spar.
Advice: Smoothed coordinates, renamed Sipkill 1.7/10B
This section bases upon HS3.0/9.0. For HLG Tailless models it is a quite good section. But thinking about SAL (Side Arm Lauch) means using Tailless at all in HLG contests is a bad idea. We still work on this item but we didn't get our Flying Wings started without one or two rolls... Don't do anything against these rolls. It's just waste of electric power. Just wonder how fast your model rolls just after leaving your hand. Don't panic.
So if you think you have a hard, crashproof model try SAL. Then you know, that it is destroyable. After this first lesson you are just on the right way to get the first really SAL launchable Tailless when designing a new one...
Ok, back to the section: The high camber of 3.0% seems to be quite much.
A section like this cannot glide like low cambered designs, fast and efficient.
Ok, this was the reason why I tested this for Indoor (HS14 "Hallengeist
1"). This model had a speed that it was almost unusable for Indoor!
This section is terrible fast, inspite of 3.0% camber!!!
Designing my HLG HS29 "Silence" I remembered this behaviour. Launching this model is a feeling like flying into a black hole: where is the drag??? I have no idea! So it was no problem inspite of open bay construction (!!!) to get second place in a HLG speed contest. The only reason why I did not win was a short touch down before A-Line...
Due to NACA 4-digit philosophy developed: NACA 0009 and my own camber line. What is it designed for? Thermal and light slope soaring. This section belongs to the same family (velocity distribution) as the EH or NACA23XXX family. So you will find here a lack in gliding performance too! But the handling is much better than the EH2,0/10 so there should be no problem when using this (see Spariane).
And: Don't use a cm0=0 airfoil like this for a flying plank! Those models have a quite good performance, but the handling is horrible!!! A rodeo ride is a nice coffee&cake afternoon in comparison to a plank using this section. I tried this, I will never do this again (HS22 Summerdream), so help me God...
Conclusion: If lack in gliding performance doesn't matter it's
Advice: Smoothed coordinates, renamed HS 3.0/9.0B
Design philosophy see HS 3.0/9.0. This section has been designed for large tailless projects like HS09 "Albatros" and here is the thermal performance simply great! The low speed gliding performance is acceptable but at higher gliding speed the performance is anything else than convincing.
Unfortunately slight nick induction (pitch axis) probably takes place (see EH series). Therefore I cannot recommend this section in general, but because of the rarely high camber there is no choice so far except EH family. The EH 2.0/10.0 is surely in comparison more than terrible, the problems around pitch axis are more than hundred times harder. The EH 3.0/12.0 is perhaps worth a try, but I do not have experiences.
For small tailless HS 3,5/12 is not suitable. HS11 "Spariane legend" flies very well at low speed but the before mentioned lack in high speed gliding performance is really remarkable. At the Northern Sea where most slopes are strong, short and not so high, the disadvantage is acceptable. But flying at wide, flat slopes where every point in gliding performance at all speeds is needed there you will not be happy with this section.
The HS3.5/12 is damn uncritical at all, stall comes very smooth, wholes in the wing doesn't really matter, some crincles in leading edge is nothing to think about. It is like ZAGI 12% that no roughness of this life can improve. No, ZAGI 12% has surly not the performance in sinking rate so there is really no further comparison.
This airfoil is very popular in Germany for very fast planks, e.g. dynamic soaring and everything else you need for slope soaring. Less drag and very fast. Thickness can be reduced to 7,5% without modification of camber. In german "Aufwind" magazine you can find a detailed analysis of this airfoil. Elevons: 25% chord. This airfoil is optimized for use of elevons. HS2,0/8,0 is outdated, you should use HS130 if you want to use an airfoil of my series for slope soaring. Minimum chord 150mm due to Rn. Please note that "classic" plank airfoils need 250mm and more! Aspect ratio 8-13, not more; e-powered planks up to 16.
This airfoil is the opposite of HS130 in many cases: center elevator is the right choice to reach optimal performance. Do not slow down using Elevator, the cm is somewhat higher than HS130. Elevator is just used to rise speed and nothing else. The basic trim is low speed (thermal) and pitch down is just for gliding/speed. Elevator: 20% chord. Minimum chord 150mm due to Rn, aspect ratio 8-13, not more.
Thermal Planks in open bay construction are still using this section. Recommended minimum chord is around 200mm. Wing loading up to 30g/dm² causes no problems. Not more! For more you have to choose EMX-07, Phönix or similar designs.
The leading edge area is designed like a stone, rough and hard. The result is a very sharp and early suction pike that cause sudden stall. So stall recovery is no problem when having low wing loading. Using high wing loading is not a good idea, the ground is the killer and a spade the right tool. Your local Balsa dealer will be a rich man in the near furture. We understand each other I think.
Conclusion: Only for lightweight open bay construction thermal planks.
Grmpf! We just discussed leading edge design on CJ-3309. If CJ-3309 is designed like a stone, CJ-25²09 is designed like a rock. I guess every user of this section took sanding paper to smooth the surface. Otherwise I do not know, why some CJ-25 models had good handling characteristics and acceptable performance inspite of higher wing loading.
Open bay constructions, ok, if there is some need to have better gliding performance than CJ-3309. All other modellers should trust the real excellent EMX-07 or Phönix or something else except this one here!
Conclusion: Only for lightweight open bay planks that need better gliding performance than CJ-3309!
Modern airfoil designed by Martin Lichte. Seems to work very well as on Stefan Siemens flying plank "Niveau". I flew against him and I can say that this section is not a bad choice!!! Ok, I killed him in gliding performance using my "Aeolus" but in thermal soaring he was always a challange!
Well known since it emerged at the Plank of Perlick/Kowalski. Seems to be dreadfully good. The somewhat smaller cm0 is something more for fast/heavier planks. No, I do not have a reliable value in addition. I estimate it according to experience on approximately +0.0 max +0.01. Due to this the Phönix is not the right choice for lightweight designs, some (mass-) inertia behind it is recommended to get rid of the low-cm problems.
Lightweight constructions can be detected by a classic rodeo flight style (instability pitch axis). Gyroscopes can conditionally help, surely not the hit. A heavier model absorbs alone due to its mass inertia this possible fast pitch nick frequency ("wippen" like SB-13).
Conclusion: On of the best sections for vacuum bagged planks I have ever seen!
This section has been developed for fast plank concepts (slope soaring) and is based on "Phönix" not the worst reference I think. It was a rainy day when I got the idea that I would like to have a section between speed and sections like Phönix or EMX-07. Models like "Sturmtänzer" and E-powered flying planks are the destination of this section. Why? The low cm design needs some mass intertia behind so it is not a good idea to build a lightweight plank with this kind of section.
Where I got this experience? HS06
and HS22 used just the same wing. HS06 is an E-powered flying plank and
it was quite well. I destructed this plank by passing a thermal with a
lot of speed. Not a good idea having an open bay construction without
D-Box and doing this! Some years later I remembered the good performance
of this plank and I build HS22, a thermal plank, using the parts of the
old HS06 wing. The handling was terrible! It is like a rodeo ride around
pitch axis! HS3,0/9,0 has been used. Ok, now you
see that things can work just because of mass inertia and in other case,
same section, same wing, absolutely not!!! And believe me:
NEVER USE CM0=0 SECTIONS FOR FLYING PLANKS!!!
This might work as before mentioned but normally does not!
The Phönix's trailing edge is somewhat fat due to building technologie.
But on a speed plank concept like "Sturmtänzer" nothing
bagging makes sense. This building technology do not need any compromise
in airfoil design so we get some more performance...
This difference is quite substantially, especially at low cls we have longer laminar run on the lower side. At low Rn the airfoil is something better too so there is no disadvantage in doing this.
© Hartmut Siegmann 1998-2001