Register

If this is your first visit, please click the Sign Up now button to begin the process of creating your account so you can begin posting on our forums! The Sign Up process will only take up about a minute of two of your time.

Page 1 of 3 123 LastLast
Results 1 to 25 of 56

Thread: TOC CAP 21


  1. #1
    doxilia's Avatar
    Join Date
    Apr 2008
    Location
    Montreal, QC, CANADA
    Posts
    4,841
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    TOC CAP 21

    I received a vintage (1984) GP CAP 21 yesterday with a 60" wing span and 550 squares. Designed for a 45, this is the smallest CAP 21 that GP produced back in the day. It was designed and drawn by Don Anderson himself back in the early days of GP. He does look very young in the brochure picture!

    In any event, I would like to scan the plans and re-design the model with a lighter (probably interlocking) structure and some modifications with the goal of producing a Gunter Hoppe 1980 TOC style model. Hoppe's model, like Hanno's Dalotel, was large and likely used dual geared Webra's - in his case 60's rather than 90's. He was swinging a TF 20x10 prop! My plan would be for a smaller model - probably in the 1000 squares size ballpark.

    I'm in search of a Don Berliner article that appeared in MA June 1982 which documents the background on the CAP 21. If anyone has this article, it would be much appreciated.

    TIA, David.

  2. #2

    Join Date
    Feb 2005
    Location
    Naperville, IL
    Posts
    1,061
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    TOC CAP 21...Gunter Hoppe!

    Great project Dox!

    My newest elf is named "Scanner". Scanner is able to take any model plan and print to 60" wide and 500' long. You can send me the GP plan, tell me the % increase, a specific wing span and "Scanner" will "make it so" for less than $50 including (2) copies. He is an extraordinary modeler, I mean really, really good and owns an architecture firm by day.

    Gunters models were of the highest quality with super shiny finishes.

    Rusty Dose
    Team Futaba
    Rusty Dose<br>Team Futaba<br>Team YS Parts and Service<br>

  3. #3

    Join Date
    Oct 2006
    Location
    Augsburg, GERMANY
    Posts
    832
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21


    ORIGINAL: doxilia
    I'm in search of a Don Berlinger article that appeared in MA June 1982 which documents the background on the CAP 21. If anyone has this article, it would be much appreciated.
    David, there's not that much background. You may know the Wikipedia articles about the CAP 10 and CAP 20. The 21 just has a new wing with slightly different planform and a modern airfoil which is flat on top and bottom from about the middle to the trailing edge (but not concave like some funflyer airfoils).

    Just for comparison, you may look at the CAP 10b plans (bootom of page) for Martin Rousseau's model, which will be too big, though. As well look at the CAP 21 fuse plan of Toni Clark's model, which seems to be too big and heavy, too. (1285 sqin, 18 lb, 33 oz/sqft)

  4. #4
    RFJ's Avatar
    Join Date
    Apr 2005
    Location
    Belfast, IRELAND
    Posts
    1,135
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    David,

    The MA article is written jointly by Don Berliner and Ed Mitchell with a short history of the full size and plans for Ed's model. This is 88" span, 1150 sq inches area for Quadra power.

    Article pdf sent.

    Ray
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Vt57522.jpg 
Views:	19 
Size:	280.4 KB 
ID:	1360059   Click image for larger version. 

Name:	Ge96579.jpg 
Views:	46 
Size:	193.3 KB 
ID:	1360060  

  5. #5
    doxilia's Avatar
    Join Date
    Apr 2008
    Location
    Montreal, QC, CANADA
    Posts
    4,841
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    Gentlemen,

    outstanding responses! Many thanks.

    Rusty, it is good to know of the services offered by elf "scanner". I'm sure they will come in handy. UStik, very interesting models you provided links for. I will be reading up in detail on them. Rousseau's site is of particular interest as he is based here in Quebec! I'm sure that didn't escape you. He also offers laser services which will also come in handy soon I hope.

    Ray, as usual, comes in with flying colours and the article in question. Many thanks Ray. The airfoils on that plan are of particular interest and the plan itself already is approaching very much what I had in mind in terms of design. Since I plan to make this an electric powered aircraft (~2000W), it will be a matter of adapting and integrating ideas from both the MA plan and the GP plan. The trickiest part of the design/model will be sourcing a canopy that fits without having to make a mold for one. This would save some time and expense. It appears though that the wing/stab work is already done for me as I was thinking of going with foam surfaces.

    After a little back of the envelope last night, I had though that an 80" span/65" length (actually 133% of the 60" span GP model) would produce a wing in the 1000 squares ballpark (977 sq in per the GP design). However, it needs to be designed to come under 10 lbs as otherwise it will be too heavy or too large for my desired scale.

    With a bit of heard work, this might be a project that would be nice to schedule for construction next winter. In the meantime, there are other scale aerobats on the horizon...

    David.


  6. #6

    Join Date
    Oct 2006
    Location
    Augsburg, GERMANY
    Posts
    832
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    In that case you should have a look at the site of a small German manufacturer with direct marketing, even though it's only in German and not very user-friendly (the website). This shop offers CAP 21 models in three different scales, the smallest of which might fit your needs. They even have a Laser 200 in three scales, a Super Star, and other interesting models. I don't know much about them, but some people here say they are good flyers.

    Please drop down the list on top of the page and select "Motorflugzeuge" (instead of "Home" ). Now select "Motorflugzeuge" (instead of "Rubrik wΓ€hlen!" ) again in the second drop-down list that appears now. You will see the three CAP 21 models and may select one to see some specifications. What you'd get is a G/F fuse with cowl in white color, wing and stab CNC-cut foam cores sheeted with obechi (I suppose) veneer (as usual here), landing gear, and linkage parts. The model/type is said to have a belly pitch (due to low wing and high stab) that may be mixed out. Don't forget to scroll down the shop page to see the Laser, Super Star, Chipmunk, and other nice models. And they sell parts like the canopies as well!

    By the way, Toni Clark has a CAP 21 history page at his website. It's translated from the ultimate French book about the CAP airplanes, but it's translated only to German (strange enough).

    And for a wing airfoil you might consider Eppler E 168 (or 169) which has the flat rear part but a more "conventional" nose part than the original (which was a French airfoil similar to other aerobatic airfoils) and was designed for aerobatic models.

  7. #7
    doxilia's Avatar
    Join Date
    Apr 2008
    Location
    Montreal, QC, CANADA
    Posts
    4,841
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    UStik,

    More great info!

    Now that you remind me, I recall seeing that German site but never noticed the CAP's. You're right that the smallest one should fit the bill. However, I believe that, being designed for glow, they might still be a tad on the heavy side ("overbuilt") for my electric purposes. Besides, part of the fun is re-designing it and building your own kit! Nonetheless, great options. The Canopy might just fit the bill! [8D]

    So I sized things to my target scale (80" span/62.6" length - might stretch it a little bit for an aspect ratio of 1.25 - i.e., 64" fuse length) and started putting some lines to paper. Very early stages but here's a draft fuse side view and wing/stab planforms. BTW, I used the E168 airfoil that you recommended. The GP model also has a very similar airfoil although it is not flat in the rear 1/2 of the airfoil - I'm not sure what airfoil is being used there.

    Here are the current specs of the model:

    Length = 62.6" (1590 mm)
    Span = 80.0" (2032 mm)
    MAC = 11.84" (300.7 mm)
    Area = 946 sq in (61.0 dm^2)
    Loading = 23.1 oz/sq ft (70.6 g/dm^2)
    Weight = 9.5 lbs (4309 g)
    Engine = .91 cu in (15.0 cc)
    Motor = 1900-2100 W (8s/75A/17x8 - 18x10)

    Some formers will follow.

    David.

    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Us54150.jpg 
Views:	53 
Size:	34.8 KB 
ID:	1360593   Click image for larger version. 

Name:	Ca82574.jpg 
Views:	33 
Size:	44.2 KB 
ID:	1360594  

  8. #8

    Join Date
    May 2006
    Location
    Berlin, GERMANY
    Posts
    26
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    At googlebooks there is apreview of this book (in french):

    http://books.google.de/books?id=AhdV...2007-3&f=false

  9. #9
    Deadstik's Avatar
    Join Date
    Mar 2002
    Location
    Rougemont, NC
    Posts
    1,300
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    David,

    Just a little note on the GP Cap 21. I've had a couple of these including the 72" wingspan version and can tell you that they are excellent flying PILOT'S airplanes. They both do exactly what you tell them but they if you try stupid pilot tricks they will snap roll into a little ball and will soon become a big pile of debris!! They are not "low and slow" planes by any means but do the aerobatic patterns very well. Thought I would throw that in so you would get an idea of the really cool monster you are getting ready to bring to life. BTW, I'd like a set of plans for the TOC one if you get that done. Take care....


    Dan
    Carolina Custom AIrcraft

  10. #10

    Join Date
    Feb 2005
    Location
    Naperville, IL
    Posts
    1,061
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    TOC Cap 21...more choices!!!

    David,

    Very fine project. Many of our models aerobatic models benefit from changing the stab/wing/thrust line locations. The TOC rules (Rusty's Rules) allow for a 15% "deviation". The Cap 21 may benefit from lowering the stab...raising the wing (it WILL change the dihedral). I am happy to introduce you to Dave G. via e-mail for a very educated opinion?

    Please add me to the "send plans" list.

    Rusty Dose
    Team Futaba
    Rusty Dose<br>Team Futaba<br>Team YS Parts and Service<br>

  11. #11

    Join Date
    Oct 2006
    Location
    Augsburg, GERMANY
    Posts
    832
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    David, I figured you'd need only a canopy, but your choice of wingspan seems to be 1:4 scale and that would mean you'd need the canopy of the middle-sized model from the German website.

    Rusty gave a broad hint, so I'd compare the model plan you're using as a template to the three-view of the original. From Deadstik's hint I infer that all CAP models are heavy, as you stated above, and I would add "too heavy". I mean it's not "scale" to build the models that heavy and I think that's why they snap so unduly. Even though the original was designed for good snap performance, it has a moderate wing loading - already a bit more than the Z-50, but even a bit less than the Su-26 and far less than an Extra or Edge. The snap behavior is very wing-loading dependent.

    As far as I know, the special airfoils above are made to give a predictable stall. The wing should give good lift before stalling and when it stalls it should do it completely. Again as far as I know, the bigger models were designed for the big gas engines available back then. Today's gas engines are very powerful with pipes and just allow all modern maneuvers (including 3D), but they are still heavy. Your intention to build a lightweight model seems to be very advisable to give a more "natural" stall and snap behavior, regardless which type of power is used. I even think that electric is still quite heavy - what is traded off by the big thrust - so glow might be even better for low weight.

    As airfoil you could as well use E 169 which is a bit thicker so it would be easier to build a lightweight wing, but maybe that's true only with a built-up wing and a thinner foam wing would be lighter but still strong enough. The airfoil on your plan might be Selig 8035 (hardly distinguishable from NACA 0014), at least it's an aerobatic airfoil and has similar thickness. Just a guess.

  12. #12
    doxilia's Avatar
    Join Date
    Apr 2008
    Location
    Montreal, QC, CANADA
    Posts
    4,841
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    Gents,

    more fine responses. Thanks.

    A little confession seems in order prior to addressing comments. As far back as I can remember, I have always had a strong attachment to CAP's. (Not so for Extra's, Yak's and Sukhoi's.) I think there are 4 of them in my shop in various forms, shapes and sizes. In fact, there is just something about boxer engines that runs in my blood. I suppose Ferrari might have something to do with it. The car is one of the few things, like soccer, that I feel national pride for, which, coming from me, is rather unusual (not in my typical personality traits).

    Because of this, and my fascination with the TOC since I was a kid (as Rusty's I imagine), I naturally gravitated toward two boxer engine models of the 1980 TOC - the Dalotel DM-165 and the CAP-21. The Dalotel, like the Curare, is a model icon of R/C heroism in my book. One of those designs and models which stood out throughout time because of who first brought it to light back in the day - Mr. Prettner. And the CAP-21, well, mostly just because it is a CAP but also because of it's importance in CAP history. There's also just something very unusual about it's empennage layout. And finally both, of course, for their nice meaty cheeks - just like my daughters!

    With that said, I am working toward the idea of producing 90 size TOC models of these two fine scale aerobatic aircraft. While the plans will hopefully be power platform agnostic (i.e., glow/gas/electric), my particular models would be electric powered (there goes my love for boxer engines!) - basically because of the simplicity of rigging, low "fuel" cost and lower overall cost of model production (motors can be considerably cheaper than engines and "fuel" need not be bought until maiden time).

    After several evenings of design work, the DM-165 workup is basically done. Before proceeding with the TOC size though, I will produce a 25 size (48" span/450 squares) mini version as a way to proof the plans & laser cut. If all's well, it will then be a fairly simple matter of scaling the model 150% to result in the desired 90 size TOC version (72" span/1012 squares).

    The CAP-21 would proceed in a similar fashion. However, unlike the DM-165 which started with a 60 size scale, the CAP is starting with a quarter scale (of full) 1.60 plan. The DM-165 plans will therefore go from 48" to 72" (25 -> TOC) while the CAP-21 plans will probably go from 54" to 81" (25 -> TOC) for a 432 wing squares 25 size model. Again, the idea here would be to proof the plans and cut prior to producing the TOC version. Note that in both cases the small (25) and large (TOC) models are 66% or 150% scale versions of each other (depending on how you look at it). For a starters, I would therefore end up with two 25 size proof models with similar wing areas but rather different planforms and airfoils. That, in itself, will be interesting to compare in terms of flight characteristics.

    As with other overambitious projects (which I seem to be setting my mind on these days... ) - The only catch will be to find the time and dedication (and cash I suppose) to build all four models. [:-] The smaller prototypes should come fairly easily while the TOC versions will require more time and dedication - something I hope to have more of once I've cleared my shop of "other" projects later this year.

    So, with that not so little confession, I should reply to your good ideas and suggestions.

    David.

  13. #13
    doxilia's Avatar
    Join Date
    Apr 2008
    Location
    Montreal, QC, CANADA
    Posts
    4,841
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    In order of thought:

    Deadstik & UStik,

    very wise comments. I have heard and read about the behaviour of scale layout CAP's. In fact, much has been said about the flying characteristics of the GP 21's in particular and all comments reflect what you are mentioning. I believe that GP's realized the turnout of their early foray into scale layout CAP's and, to that end, made x% layout modifications to later and current CAP's in order to tame their behaviour. The 232's I have certainly have lower stabs positioned further back and in some cases, higher wings as well. At 6.5 lbs, the 40 size/550 square GP model is certainly a lug and as soon as I unrolled the plans, I saw why. Planform aside, I wonder, as UStik suggests, if the "ball snapping" tendency of those kits was due to the massive weight of them. Back of the envelope gives me a 28.3 oz/sq ft max wing loading for the 40 size model! [X(]

    If I ever build that model (that's not why I bought it really), I can see substantial wood disappearing and kit bashing that would take place.

    For the TOC (and proto 25 sized) versions, the question remains - should I deviate from fuse planform as well as wing airfoil or should I try and stay closer to scale while making sure I build light? My target max weights would be 56 oz (25 sized) and 152 oz (90 sized) for loadings of 18.7 oz/sq ft and 23.4 oz/sq ft, respectively. For comparison, the Dalotel would have slightly lighter loadings (if built to the same weight) of 17.9 oz/sq ft (25) and 21.7 oz/sq ft. What are your thoughts on these wing loadings in terms of "snapping" tendency for the electric CAP's? Does it warrant scale deviation or should I keep them scale provided they are built to these specs? Or perhaps they are independent decisions and scale deviation for the CAP is worth considering anyway?

    The wing airfoil I used in the plan shown above is a modified E168 (thickened and stretched) so it's no longer a 12.45% airfoil. The thicker E169 14.4% airfoil might be closer to the modified E168 shown (haven't checked). I adapted the airfoil based on "gut feeling" and so that it would match the percent thickness of the Aerospatiale V16F airfoil of the full scale (presumably also used in the quarter scale version). "Gut feeling" also tells me that, at least raising the wing a tad wouldn't be a bad idea. Question is, should I lower the stab by the same amount? Of course, "gut feelings" have little to do with aerodynamics so perhaps you will all have some good suggestions on these questions.

    Rusty,

    introduction to Dave G. and his opinion on the subject would be most welcome. Please feel free to send him my email address (you should have it in my last PM) and/or send me his. I'm sure he would have some excellent and conclusive suggestions on the "new layout".

    Finally, plans will of course be available to all (perhaps with a laser kit) once they are finished and have been "cut verified". I expect a Dalotel thread to also come alive once I have materials in hand. Now, where are my elves!?

    David.

  14. #14
    doxilia's Avatar
    Join Date
    Apr 2008
    Location
    Montreal, QC, CANADA
    Posts
    4,841
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    Viktor,

    thanks for that link. It looks like a great read!

    Know if there is a way of producing a printable version easily? I'll give it a shot.

    David.

  15. #15
    doxilia's Avatar
    Join Date
    Apr 2008
    Location
    Montreal, QC, CANADA
    Posts
    4,841
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    I found an interesting thread discussing the differences of S8035 vs N0014:

    http://www.rcuniverse.com/forum/m_160720/tm.htm

    It would be interesting to find a similar discussion (or perhaps wind tunnel tests) on the difference between E168 and N0014. This latter looks to be very similar to the airfoil used in the GP CAP.

    If the desire is to keep fuse planform (wing/stab positions) on the CAP, would it be preferable to use something like E168 or N0014 to prevent "snapping" tendencies at low speed?

    Attached is a drawing comparing S8035 & N0014. For comparison, beside it are the E168 & E169 flat rear airfoils. Max thickness of the latter appears to occur at about 26% chord.

    David.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Jh15603.jpg 
Views:	16 
Size:	13.8 KB 
ID:	1360940   Click image for larger version. 

Name:	Mj24400.jpg 
Views:	15 
Size:	56.8 KB 
ID:	1360941  

  16. #16

    Join Date
    Oct 2006
    Location
    Augsburg, GERMANY
    Posts
    832
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    David, I don't think the snapping noticeably depends on the vertical position of wing and stab. That's more a matter of belly pitch in knife-edge, what the originals were (still) not made for. Hanno "cheated" on his Dalotel by lowering the stab. (Just can't find the Dalotel thread here.)

    Snapping surely depends on wing planform and airfoil, but I think wing loading is paramount. A small drive allows lighter structure and maybe even the same performance as the usual heavy models. Maybe it's just impossible to build a 40 size CAP light enough so you have to modify it somehow. I'm not impressed by the idea to build a small proof model, at least I wouldn't even try to fly it. I would expect substantial differences in flight behaviour to the bigger versions due to inevitable higher "relative" wing loading and Re number effects. Even the 1:4 version will and can not fly like the original. The test pilot reported a smooth and stable stall without wing dropping. As Deadstik said, the CAP model is a pilot's aircraft, meaning the pilot has to avoid slamming the sticks to their stops. A high-wing-loading model has to be flown quite fast and is not able to fly sharp corners - that's all.

    You may read this and this discussion of aerobatic airfoils to find very interesting characterizations. The flat-rear airfoils just give a sharp stall instead of a smooth stall of the NACA 4-digit series. I have a book with measured behavior of E168 and 169. For a small model you should use the thinner airfoil. The thicker one has more stall hysteresis and a soft stall with little lift at small Re numbers. Both have small drag over the whole AOA/lift range. So they should be really better than S8035 or NACA 0016, regardless of model size and wing loading. By the way, maximum thickness is at 25% / 27.9%, respectively.

    Me seems your TOC size model would still be too small to come closer to the original, even at the ambitious low weight you specified. I think Hanno knew why he built his Dalotel to the maximum size allowed (and still "cheated" ), he just didn't tell it explicitely. You could cheat by reducing the taper ratio.

  17. #17
    doxilia's Avatar
    Join Date
    Apr 2008
    Location
    Montreal, QC, CANADA
    Posts
    4,841
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    UStik,

    More food for thought... I've always believed (perhaps incorrectly) that more concentric models (flying surfaces closer to the thrust line) tend to fly better roll maneuvers due to their indifference to upright vs inverted flight. Because of this, I've also assumed (again perhaps incorrectly) that they have a more gentle stall behavior (i.e., less wing dropping) with less tendency to snap out of the sky. It is with this in mind, that my "gut feeling" (I'm just a fledgling designer...) was telling me to bring the surfaces closer to the thrust line. Aside from knife edge performance, is this also why Hanno lowered the stab on the Dalotel? (I wish I had a copy of his plans.)

    I'm not sure what you mean by a "small drive" but perhaps you're referring to lower torque/thrust/power platforms allowing one to build lighter models? I'm fairly certain that one can build just about any aerobatic model "light enough" these days. If we consider the wing loadings of typical aerobatic/3D electric models today (even small models), they have loadings that are exceptionally low (high single digits/low teens). Just by glancing at the GP 40 plans, I can see how I can take out a pound without even thinking much about it. 2 lbs would require a little more work but I think also doable for a 4.5 lb/550 square model. In fact, I don't think the kit will ever be built because of this but the plan might...

    In short, what I'm getting at is my question as to why you don't believe in a smaller scale version (from any standpoint)? I certainly don't expect the 25 to necessarily be a good proxy of the flight performance of the 90 but it does help to at least verify the laser cut plus; perhaps a little flight experimentation too.

    Switching gears, I'm pretty sold on your recommendation for Eppler airfoils. If I understand correctly, if you had a recommendation for a 25 size model, you would recommend E168 while for the 90, you might recommend E169? Or perhaps, compared to the full scale, both these models are "small" and would be better off with E168?

    I have high expectations of being able to reach 9.5 lbs on the Dalotel. For the CAP, at what I'm converging on being 81", I'm not so sure. I'd like models with ~1000 wing squares and because of the CAP's wing planform, large span is needed to reach that area. The main unknown in the weight equation (as you suggested) is how much the wing & stab will weigh if built with foam cores (I was hoping for cores on both models). I'm fairly confident in that I can design/build a pretty light fuse airframe. A little math might give us a good estimate of the flying surfaces weight (considering that classic 60 size thick airfoil models can be built to ~25 oz wings...)

    As a very crude estimate, do the following figures seems realistic for a ~1000 squares model?

    Wing = 40 oz (2.5 lbs)
    Fuse/Empennage = 48 oz (3 lbs)
    Equipment/Power = 64 oz (4 lbs)

    If not, perhaps I need to reconsider things. Good to know about the location of max thicknesses.

    I don't quite follow your last paragraph - would you mind clarifying?

    Thanks for the contents of your PM's!

    David.

  18. #18
    doxilia's Avatar
    Join Date
    Apr 2008
    Location
    Montreal, QC, CANADA
    Posts
    4,841
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    On a related note; any idea what this Dalotel airfoil might be?

    Looks closer to N0014 but with a max thickness closer to the LE.

    David.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Ig12388.jpg 
Views:	32 
Size:	83.9 KB 
ID:	1361037  

  19. #19

    Join Date
    Oct 2006
    Location
    Augsburg, GERMANY
    Posts
    832
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    As to Hanno's Dalotel, I just compared the picture to the original's drawing. I think the model has less dihedral and a symmetric airfoil and maybe even more modifications. The original comes close to the Z-526 in my eyes. With both you have to decide building a scale model (also in behaviour) or a TOC-like flying model (looking roughly like the original). The CAP is nearer to modern planes but may still need some modifications. Actually, I'm not a designer but like to figure out the aerobatic designs. I've compared quite a few of them in different model sizes and at different weights, but not the CAP so far, so I'm all but sure.

    My last sentence was wrong. I actually meant increasing the taper ratio or reducing taper for a less tip-stall prone wing planform. I think Hanno followed "bigger flies better" by building his model as big as possible. Not that the snap behavior is better, most important is the lower "relative" wing loading.

    You are right, today's models are very lightweight and less airframe weight requires less drive power and weight. Besides, the low wing loading makes for slow flight speed and low drive power. Obviously, Hanno already used the same trick. I think the two .60 engines combined were still not that powerful for the big model, but the gear made a slow-turning big (high efficiency) prop possible and that made for more prop power than a bigger gas engine.

    But "bigger flies better" simply means that some movements are scale-like at the same cubic wing loading and most of them even at the same quad wing loading as that of the full-size airplane. That requires a very low absolute wing loading and weight for small models. One reason I admire Ken Bonnema's Brushfire is its "consistency. It's quite big (850 sqin) and has to be built carefully for low weight (lightening holes in the foam cores, film covering, ...). Deadstik achieves 8 lb, giving a wing loading considerably smaller than that of Curare. (BTW, the Curare airfoil could be E169, I should check that.) Still its relative wing loading is quite high (22) so it flies more like a jet aircraft. Fortunately, or consistently, it was designed in the ballistic pattern era when jet aerobatics were imitated (maybe triggered by the Blue Angel) so it even looks like a full-scale jet. Problem with the scale models of full-size aerobats is that they look like an aerobat but fly like a jet. But maybe that's only my problem because I'm a purist.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Tr51725.jpg 
Views:	9 
Size:	46.5 KB 
ID:	1361051   Click image for larger version. 

Name:	Ez82916.jpg 
Views:	16 
Size:	106.5 KB 
ID:	1361052  

  20. #20

    Join Date
    Oct 2006
    Location
    Augsburg, GERMANY
    Posts
    832
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21


    ORIGINAL: doxilia

    On a related note; any idea what this Dalotel airfoil might be?
    Eppler designed more aerobatic airfoils that are definitely not suited to low Re numbers, though: E472-475, E479. Maybe one of these.

  21. #21
    doxilia's Avatar
    Join Date
    Apr 2008
    Location
    Montreal, QC, CANADA
    Posts
    4,841
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    UStik,

    that is one heck of a picture! Not only do we have Hanno and the Dalo at the 1980 TOC in the foreground but, I'd say that is Hoppe's CAP 21 in the background! Unless, since we can't see the wing, it is Bonetti's or Tracy's CAP 20 (same fuse/elliptical wing).

    I compared some other Eppler airfoils to the Dalo wing and found the E472 to be the closest match. Actually, at ~12% it is still too thick compared to the airfoil chosen by Obi. Fluid dynamics aside, hopefully, this will translate into an airfoil that will fly the 72" TOC model favourably as well as the much smaller 48" version. The proof is in the pudding I suppose.

    Actually Obi, coincidentally, published a first pass at his Dalo in MAN June 1982 - exactly the same issue of MA for the CAP-21 - nice! In that case, his model was a 40 size 54" span and all indication in the review was that the model flew very well. I hope that trimming 6" off the span on an improved design won't change that!

    Well, I guess it's time to put a few more lines to paper...

    David.

  22. #22

    Join Date
    Feb 2005
    Location
    Naperville, IL
    Posts
    1,061
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    TOC Cap 21...more choices!!!

    Suggested stab/wing location changes...

    I sent the fuselage drawing to Dave Guerin and he suggested that the stab be placed on the thrust line and the wing moved up, closer to the thrust line. How high to move the wing is a guess and will require the dihedral fiddled with (less) which is easier with an aluminum wing tube.

    Cap Canopy- I have attached a photo of a Great Planes 27% Cap 232 part #GPMA1410, $9.49 15.5" long, 7" wide and 5" tall.

    Dox- I love the .20 - .25 size Dalotel! I will have the elves make a set of wings and use the extra K&B .19 I have and the E-Flite retracts. Thanks for your engineering. Can I send you a set of the wings/stabs as a courtesy for stealing your plans?

    Rusty Dose
    Team Futaba
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Fc90330.jpg 
Views:	15 
Size:	5.9 KB 
ID:	1361505  
    Rusty Dose<br>Team Futaba<br>Team YS Parts and Service<br>

  23. #23

    Join Date
    Oct 2006
    Location
    Augsburg, GERMANY
    Posts
    832
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    David, it was late yesterday, too late for me, and I even forgot about the unusually high aspect ratio (7.1) of the CAP 21 even though you mentioned it. I think that may contribute to the snap behavior. The Z-50 has similar behavior with only 5.9 aspect ratio, but it has conventional NACA 00xx airfoils. After some experimenting I'd say it should be possible to make the CAP less snappy with a suitable airfoil. It shouldn't lose much lift when stalling, what the NACA 00xx do, though, and the E 169 does as well. The other modern aerobatic airfoils with very forward max thickness (less than 20%) might do the trick. E 472, 473, 474, 475, and 479 might do as well but they are suitable only for bigger models and have much increase of drag with AOA. (By the way, did you read that they tested the type in a spin wind tunnel?)

    The CAP 21 has a quite big stab and huge elevator and long tail moment arm so you may pull it to a stall AOA very easily. Due to the high aspect ratio it will stall even at 17 degrees. Besides, it has a pronounced mid-wing to tip stall (giving better snaps) due to the special wing planform. Not as much as modern aerobats but enough to require a special airfoil (my guess, I'm not an expert). Like me, you may find it interesting to compare the planforms of various aerobats (Z-526AFS, Z-50LS, CAP 21, Su-26M, EA-300S, Edge 540) with comparison to elliptical planform.

    My simulator is good but still a rather simplified rendering of a model and stall aerodynamics. I tried the behavior with a 1:4 scale model of the CAP 21 and found it snaps and spins like crazy with only 25 degrees elevator (30 degrees rudder aren't even needed to snap). An airfoil which doesn't lose lift in stall calms things down.

    There's no parameter for the stab position, but moving the wing 2" up turned the substantial belly pitch into a bit canopy pitch (1.5 degrees dihedral unchanged). I find the belly pitch not really bothersome and would mix it out.

    By the way, 1:4 scale (2.02 m / 79.5") really seems too small. It gives 890 sqin wing area, and with 9.5 lbs weight the model is somehow similar to the Brushfire. You might deviate from exact scale by clipping the wings, as you mentioned, what would reduce the snappyness and make it easier to build a strong but lightweight wing.

    A 1:3.5 version, exactly scale (2.31 m / 91"), at 14 lbs (6.35 kg) is noticeably less snappy, and if you could build it to 11 lbs in that scale it would be just perfect! By the way, the three-view of the original seems to show about 1 degree incidence for the wing. Even less than 1 degree removes the belly pitch but requires a bit more down elevator inverted. Another choice.

    I used 0.25 degrees wing incidence and 0 degrees stab incidence (4% static margin), giving neutral trim upright and nearly neutral inverted. 3% static margin might make it neutral both upright and inverted. But how about giving both wing and stab 1 degree incidence. That makes the plane look better in the air, again both upright and inverted.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Ca80981.jpg 
Views:	10 
Size:	26.0 KB 
ID:	1361589   Click image for larger version. 

Name:	Xs57140.jpg 
Views:	10 
Size:	25.2 KB 
ID:	1361590   Click image for larger version. 

Name:	Ot46839.jpg 
Views:	8 
Size:	26.1 KB 
ID:	1361591   Click image for larger version. 

Name:	Ex68292.jpg 
Views:	10 
Size:	27.3 KB 
ID:	1361592   Click image for larger version. 

Name:	Pa35089.jpg 
Views:	11 
Size:	27.7 KB 
ID:	1361593  

    Click image for larger version. 

Name:	Xo90788.jpg 
Views:	12 
Size:	25.6 KB 
ID:	1361594  

  24. #24
    doxilia's Avatar
    Join Date
    Apr 2008
    Location
    Montreal, QC, CANADA
    Posts
    4,841
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    ORIGINAL: BERUSTY

    TOC Cap 21...more choices!!!

    Suggested stab/wing location changes...

    I sent the fuselage drawing to Dave Guerin and he suggested that the stab be placed on the thrust line and the wing moved up, closer to the thrust line. How high to move the wing is a guess and will require the dihedral fiddled with (less) which is easier with an aluminum wing tube.

    Cap Canopy- I have attached a photo of a Great Planes 27% Cap 232 part #GPMA1410, $9.49 15.5'' long, 7'' wide and 5'' tall.

    Dox- I love the .20 - .25 size Dalotel! I will have the elves make a set of wings and use the extra K&B .19 I have and the E-Flite retracts. Thanks for your engineering. Can I send you a set of the wings/stabs as a courtesy for stealing your plans?

    Rusty Dose
    Team Futaba
    Rusty,

    first things first,... oh yea!

    I'd actually decided to source the foam cores for these projects as it is not a particularly fun aspect of the hobby. Besides, designing is time consuming enough. I was waiting to hear back from my "foamy" elf but he seems to be missing in action. So, with that said, yes! I would very much appreciate a set of wing/stab cores for the Dalo 25. A laser cut kit is also in the works and should be available by mid February if that interests anyone. I was actually hoping to get started on that model ASAP so an ETA of how long it would take for the cores to be made would be appreciated. They are actually simple cores to cut if there's such a thing. I'll contact you by email with further info.

    You will see that my plans have already been designed around the E-Flite gear (as many others including the UFO 25 I'm working on). I'm not sure how well a K&B .19 will cope as the plans are scaled around a 25-32 size engine - in my case an electric 4240-750 (~600W) for a 3.5 lb model.

    Good idea for the CAP 21 canopy. I actually have one of those under my bench but the 27% GP CAP 232 is a much larger model (1.6 engine) even if it has a shorter 79" span (bigger area - 1168 sq in). The Canopy is 15"x7" while the TOC CAP 21 is roughly 11.5"x6". I'm not sure how well a cut-down of the GP canopy would work. The German canopy might be better suited but I haven't looked into it yet. Of course, a readily available FG cowl and wheel pants would also spare considerable work although I can see how to devise a wood cowl (not quite as nice).

    I'll address Dave's suggestions in the next post to keep design and technicalities separate.

    David.

  25. #25
    doxilia's Avatar
    Join Date
    Apr 2008
    Location
    Montreal, QC, CANADA
    Posts
    4,841
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: TOC CAP 21

    Rusty,

    Thanks for your call to D.Guerin.

    The wing is actually already floating somewhere further up in the fuse. I am determining how to finish the fuse bottom without loosing too much of the original scale appearance. The cowl rear bottom and wing TE location on the fuse are not at the same level which is something that is taken care of by the wing airfoil. With a higher wing, some compromise has to be met on how and where to break the angle of the fuse bottom. The easy solution is to just extend the fuse rear to the fuse front at the cowl junction but this might not be very elegant. Lowering the fuse at the wing TE (greater lower fuse aft angle) might also be a better way to preserve scale lines.

    All this of course leads to the idea of plug-in wings which I'd prefer (for space constraints if nothing else). You mention that an alum tube helps with adjusting dihedral angle - how so? However, landing gear struts are mounted to the wing LE and the wing hold down plate in the fuse. If the wings are designed to be plug-in, I'm not sure that the tube would withstand the stress of a 10 lb model landing on the wing panel LE's!? I know this was done with early turnaround pattern designs which had panel retracts but they were located much further back. Any thoughts?

    I was taking a look at the GP CAP EAGLE 580 EP (Matt Chapman's model) and see that the stab has been lowered to well below the thrust line. It is also moved back a tad so the stab TE is no longer inline with the fin LE. Angle cuts in the elevators are needed to clear the rudder. Both of these changes break the "scale" appearance in my opinion but I'm sure that the rearward stab position smooths elevator response somewhat.

    The GP 27% CAP 232 has a slightly higher stab position (still not scale on the "fuse top" where it should be) but it is in the correct rear/aft position. So, with that brief analysis, it seems that Dave's recommendation to leave it in the scale rear/aft position and lowering it to the thrust line stays within a 15% TOC deviation (for what it's worth) while maintaining scale appearance.

    As far as the wing goes, I will probably locate it higher up in the fuse at the equivalent % stab departure from its scale position. This seems like an even scale departure for flying surface locations.

    I look forward to any feedback on these comments.

    David.


Page 1 of 3 123 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
All times are GMT -6. The time now is 10:10 AM.

SEO by vBSEO 3.6.1 ©2011, Crawlability, Inc.