LS171Malibu

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Does anybody have the HQ/A-0/12 airfoil in a core or dat file? If so, I am in neeed. [8D]

Cheers,

countilaw

Blake,
What are you intending to build? Something interest?


Does this look familiar?

Frank

doxilia

My Feedback: (3)

Blake,

You should be able to produce the polars by using X-Foil (MIT) and the info on Dr. Quabeck's website as to the program parameters.

I guess XFoil is at the core of Profili so you should also be able to regenerate the "Akro 0/12" foil using the latter.

David

LS171Malibu

My Feedback: (16)

Looks good Frank, have you flown it yet?

LS171Malibu

My Feedback: (16)

Ah, you make it sound so simple!

doxilia

My Feedback: (3)

Blake,

It's worth downloading Profili and playing around with it if you are researching airfoils or want to produce a non common foil. It's also a great tool because it's quite standard and easy to transfer info between modelers.

David

LS171Malibu

My Feedback: (16)

Thanks Dave. I don't read German but with your help I was able to get the files!

Cheers,

countilaw

Blake, flew it last weekend. I let another member fly it to get his opinion. He statement while flying it was "Sweet !! " I'm a little prejudgist, but "really nice", "very stable" and "a lot of fun".

I need to build a couple of pattern planes for next season. I will need some foam cores cut.

Frank

doxilia

My Feedback: (3)

While not as easy and straight forward as having a simple polar data file in hand, Profili is definitely worth playing with if you are into model design.

Don't forget that you can punch in web addresses into Google translate to get an English version translation. Profili is developed by an Italian, while I believe Dr. Quabeck is Austrian although his website is hosted under a German domain (.de). Regardless, his site is obviously in German.

David

limeybob

My Feedback: (6)

Here it is generated by Profili Pro from a raster image
Extension is .txt, but it is a .dat file. change extension to dat to use
limeybob

doxilia

My Feedback: (3)

Blake,

I've been doing a little bit of airfoil research for the re-design of an MK Super Chipmunk 120. After looking at the airfoils you posted, I was intrigued just by looking at them. As it turns out, for quite some time, we have been using symmetric aerobatic airfoils with comparatively prominent frontal (30%) sections. Examples of such "sharp" airfoils can be seen in classics everywhere: Deception, Compensator, Bootlegger, Aurora, Beetle, and, as it happens, also the series of MK 120 size designs as well as most of their classic pattern designs.

I have been researching, on and off, for such airfoils since I first came across the unusual Deception airfoil. Now, that I'm working on the Chipmunk, I was curious to see if I could find any airfoils in the standard libraries that would come close to that used by Kato in this "aerobatic F3A adaption" of the Scholl Super Chippy. News flash!! The HQ/A-0/14 (14% foil) is almost a dead ringer with the Kato 120 foils. Very slight differences are noted primarily in the rear 50% of the foil where the Kato foil is slightly thicker but the key aspect of the similarity lies in the frontal 30% which is very close indeed.

I now suspect that Kato "chose" the foils he did for these pattern classics as they probably have better stall characteristics and "snap entry behavior" than the classic NACA 00xx and Selig S8035 type foils. In short, whatever led you to inquire and research this foil, it happens to be a particularly good airfoil for aerobatic RC aircraft.

I have posted a comparison file (JPG and PDF) of 14% thick foils which can be used in aerobatic RC applications. I was hoping to "discover" the exact foil used by Kato and the closest I came was the HQ foil so thanks for bringing it up! For our purposes, I am going to stick with the original Kato foil as it now strikes me as it must have "magical" properties to it...

BTW, there is a simple program called Aeroplot (http://www.adaptivecnc.com/AeroPlot/Aero%20Plot.htm) which you might like and find useful for fooling around with foils. It is quite utilitarian and is limited in scope compared to Profili but it does a quick job of basic airfoil related tasks. I hope it is of some use to you.

Save files as "14% Aerobatic Symmetric Airfoils (.jpg or .pdf)".

David

doxilia

My Feedback: (3)

Minor comment:

The skins shown on the airfoils depict 1/32" sheeting on foam cores.

1/2 lb/cu ft virgin foam and 1/32" balsa skins, laced with CF where appropriate, is my new approach for ultra light foam wings.

David

LS171Malibu

My Feedback: (16)

Thank you Bob. Rockwall, that is close to myself and even more so to Frank. Do you by chance cut cores, we are both in need?

Cheers,

LS171Malibu

My Feedback: (16)

David,

I am glad to have been able to help! And even more excited for your enthusiasm toward this airfoil. While trudging through old threads I had seen a fellow suggest that it may be good for pattern, and while not being an engineer or anywhere close, it did seem appealing. I appreciate your analysis, and question the 14% example. My first thought is to take that as a hint, but I would like to know what considerations should I take into account when determining a chord thickness? I have read to make it as thin as possible, but no explanation as to why...

Where do you get half pound foam? I like this idea!

Cheers,

limeybob

My Feedback: (6)

I have a home made foam cutter, I use on occasion.
Have you thought about making a foam cutter?
limeybob

LS171Malibu

My Feedback: (16)

I have a homemade one I acquired at some point, and a buddy has a feather cut someone gave him. He nor I have experimented with them yet. I want do do plug in wings and am afraid to cut for the socket, maybe some day.

Have you used the HQ/A-0/xx airfoil?

doxilia

My Feedback: (3)

Blake,

HQ designed these airfoils for sailplanes. The symmetric foils were done with stabs in mind reason for which you are unlikely to find foils thicker than 12% in DAT libraries. Having said that, modifying the thickness is as basic a foil modification as one can make.

The 14% wasn't as much a hint as the thickness of the foil I was looking to produce for my application. As we know, classics had thicker foils than modern pattern designs but their loading is comparatively higher. Having a thicker foil allows us to slow down for landing and certain maouvers before stalling given the high loading. By comparison, modern designs have lower loadings (more area) and their foils can be made relatively thinner.

I can't recall off the top of my head but I believe the Kaos has a 17-18% foil, compared to 16% on the Dirty Birdy and 14% on later classics such as the Aurora and early turn-around designs. Modern pattern has foils which may well be on the order of 11-12%, but that's just a bit of an educated guess as I don't fly modern 2m pattern.

Personally, I feel that mixing 30-40 year old designs with very thin modern foils won't work out too well.

David

PS 1/2 lb foam is used by several core cutters. The older and more common standard was to use 3/4 lb foam.

countilaw

Bob,
I've thought about making a cutter, but run up against a power supply. I made one years ago using an old train set control for the power supply. But it just didn't seem to get hot enough to cut very fast. It was just easier to go see Johnny Casburn and use his cutter. It was really fast and professional.

There was a company in Irving, United Foam Inc, they made foam blocks used in floatation wharfs that you see at the lakes around here. They always had large blocks of foam that didn't expand right. But they were good enough for foam wings.

I am in need of cutting some cores for a Super Kaos to fly in next years SPA. I wish I knew what Blake was working on. Could be interesting.

Frank

LS171Malibu

My Feedback: (16)

Frank,

You can get Super Kaos cores from Eureka. I am setting up to build something for the OS 95 (my first attempt a using a four stroke in pattern). I have Curare and Sequel short kits, but am leaning to the Sequel due mostly to the position of the wing, width of the fuse, and long tail moment. It has a flying stab as well, using the Violet Flying Fork, that I think would be interesting to use. I want to do plug in wings, and also will be going to conventional gear with fuse mounted mains. This will be my first attempt at covering with dope and tissue, and painting as well. All in all it will be a complete departure from my traditional style in most aspects.

My Compensator is very nice, and should be extremely competitive in our area, so I wanted to experiment in the unknown (for me).

Cheers,

countilaw

Verrrrry Interesting...... I have always liked the flying stab concept.

Frank

Timthetoolman1

My Feedback: (6)

Hey Dave, the Dirty Birdy has a 17% wing. Coincidentally I have the root profile from CompuFoil setting in front of me. We have been working on it trying to get it to fit the fuselage better but it seems they had a funky wing when they did their fuselage. Maybe someone got happy with the sand paper in spots.
I’m curious about Profili. I’ve been using GMFC as a CNC controller but it there are a couple of things I would like change on it. I’ll have to look into Profili. I able to make individual wing profiles in CompuFoil and save them as a .cor file and open it in GMFC which seems to be working. I just wish we would change to the metric system like they promised us 35 years ago…hehehe. GMFC is only in metric but it’s my preferred measuring units.

Blake, Gary A. and I have been talking about making plug in wings, no doubt a conversation between you two also. I was just looking at a spare DB fuselage and thinking I could make the canopy come off but it would be difficult to install the components in that small space. We are working on a faster way to make the wings so we can change them up a bit. I want to stick with one fuselage and make build changes first to get the quickest reproduction time so we can tweak it afterwards.

The foam cutting power supply can be made simply with a dimmer switch and a power supply from Grainger. I worked through this with an electrical engineer and he verified there is sock isolation from the switch and it seems infinitely controllable. It seems a lot better than the one that comes with the feather cut.

LS171Malibu

My Feedback: (16)

Well, my curiousity is up. Is this Tim? Do you have the ability to cnc cores?

Timthetoolman1

My Feedback: (6)

'Ok, you've got one, reel him in'...lol.

Yes, it's me and yes I have the ability to make CNC cores.
However, I just started this week so I'm still working out the bugs.

Tim

LS171Malibu

My Feedback: (16)

Sweet!!! I'll go buy some foam!!!

Timthetoolman1

My Feedback: (6)

Strange, I didn't know they made 1/2' foam. I always ordered 1' but it holds up better in the vacuum.
I use 3/4" cloth on mylar to cover my wings so I don't have any weave to fill.

The cutter was on loan from someone else and unfortunately had to go back tonight. If I can run across a perminent one I'll let you know.

Tim