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Dihedral or flat wing on a retro design.


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I am toying with the idea of building a scaled-up version of the Hep Cat from a free plan for a 46" version. I am trying vintage airframes for my first time, but I have an electric Junior 60 awaiting a maiden flight, which I am looking forward to.

As I might not really take to a three channel plane (the J60 might be enough for that), I am thinking of making the wing as a flat, aileron equipped version. A flat wing will look odd, I guess. What small dihedral can I use (simple straight wing panels) that will look more pleasing but not create control problems?

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If you want flat wings and ailerons, you've picked the wrong plane.
Have you considered a Wot 4?

To put it another way, imagine someone who wants a Wot 4, but he wants it vintage, so he scraps the ailerons and builds in generous polyhedral (ridiculous).
IMO, the choice of model should be related to the way you want to fly...

The Hepcat built and flown as intended is a super old plane.

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Yes I agree 'flat wings' do look a bit odd David, so you could reduce the dihedral to just a couple of degrees or so. This might improve the aesthetics without introducing any odd handling problems which, as you suggest, are likely if you fit ailerons to a wing with (eighteen degrees of) dihedral. I agree with Brokenenglish and David P, the Hepcat is a nice vintage model but I can see why you might like to build a four channel version if you have just completed a three channel Junior sixty. Have you considered building a four channel Super Sixty instead perhaps, as it is a bit bigger and there are build threads on this forum? At the end of the day it is your hobby and it doesn't matter what you do as long as you have fun doing it.

Alternatively if you fancied a faster flying high wing 'retro looking' 4ch model, how about Peter Miller's Peggy Sue Two? You could do a leccy conversion too!

Edited By Piers Bowlan on 11/04/2020 17:52:56

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Hi David.

The Hep Cat is of course a 'free flight model', yes, you just launch it and let it go! Therefore, as with all free
flight models the Hep cat is self stabilising thanks to the dihedral wing. That is, if a gust of wind hits it from
the side causing it to pitch or roll it will endeavour to stop this from happening and correct itself. The
same effect can happen if we try to turn the model with radio control, it will try to prevent this from
happening and the tail will start to wag from side to side. The outcome of this is called 'Dutch Roll', a
common problem with rudder steered aircraft. A simple fix for this, as you say, is to fit ailerons also to reduce the dihedral by 50 percent, but not flat.

I converted a Keil Kraft Chief and a Halo to electric power and RC in this manner. Both of these were rudder steered and flew with no sign of 'dutch roll', thanks to the reduction of the dihedral wing.

Hope this is of use to you. Please let us know how you get on.

DW

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Thanks for your input... I like the shape of the Hep Cat (and similar).

Although I am thinking of adding ailerons, it doesn't necessarily follow that I must throw it around like a Wot4. I'm looking for a more gentle and slower experience. At best, if it flew in a similar manner to my F5J models (aileron equipped E-gliders), where it could use aileron and/or rudder for gentle turns, I would be very pleased. It will have some other significant changes from the plan version.

I hope to keep the vintage police away by having it look the part, even if it is likely to be covered in film (another no-no, I guess) and have radio control.

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Posted by David Hall 9 on 11/04/2020 18:23:33:

Thanks for your input... I like the shape of the Hep Cat (and similar).

Although I am thinking of adding ailerons, it doesn't necessarily follow that I must throw it around like a Wot4. I'm looking for a more gentle and slower experience. At best, if it flew in a similar manner to my F5J models (aileron equipped E-gliders), where it could use aileron and/or rudder for gentle turns, I would be very pleased. It will have some other significant changes from the plan version.

I hope to keep the vintage police away by having it look the part, even if it is likely to be covered in film (another no-no, I guess) and have radio control.

 

 

Each to his own but what you've said makes no sense to me. You want "gentle" turns.? Why? Part of the beauty, in my eyes, of dihedral turns on rudder is the banking and dynamic changes to shape.A rudder only plane can do VERY gentle turns indeed...or a total.roll.  (I once rolled a full size Tristar on rudder only.  In the sim. thankfully...)

 

But like I said...each to their own.

 

 

Edited By David perry 1 on 11/04/2020 18:40:45

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