Citabria Pro

[Kittyhawk]

Right at the outset the man that commissioned this model stated that he had zero interest in aircraft and aviation.
Somewhere along the way he had come across a photo of the Pro and the aeroplane appealed to his sense of form and style and I guess he's entitled to his peculiar artistic opinions given that he earned his living as a concert violinist.
I had never heard of the Citabria and presumed it to be a European, possibly Italian but no, its built by Champion Aircraft in the USA and the name is nothing more exotic than AirBatic spelt backwards.
Champion Aircraft built over 1000 Citabria 7eca's in the 60's which is a high wing twin seat enclosed cabin sport aeroplane and the Citabria Pro is a derivative of that, sharing the same wing, lower fuselage and empennage. The prototype went through several iterations during its development in 1968 as an aerobatic aircraft and with its final approvals granted was to enter into immediate production. Unfortunately a fire then swept through the facility destroying everything associated with the Citabria Pro so the prototype was the only one ever built.
Consequently all that remains are just a handful of photos and a few pages of very crude and basic plans. As a result, the model is my rendition of the aeroplane and cannot be regarded as a scale model.

Main components cut to required thickness and profiles.

Fuselage shaped.

Tail on and wing glued up. Wasn't going go cut the wing for a 1° dihedral , but, might as well do it right..

Wing mounted.

Doing a wheel alignment.

 

[AES]

Lovely work as usual Kittyhawk.

Just as a matter of interest, our local gliding club has a Citabria as a glider tug (I think it's got a non-standard up-rated engine) and I believe there are several of them here in Switzerland.

 

[Jameshow]

Lovely

Do you use the right chord depth? And or aerodynamic profile?

 

[Kittyhawk]

Lovely

Do you use the right chord depth? And or aerodynamic profile?

Yes - as far as wood allows. Generally the trailing edges of wings and tailplane are fractionally thicker on the model than in reality as too fragile otherwise. Usually the plans will contain a number of cross sections along the length of the wing and from these I make templates to ensure the correct shape. The Citabria plans were very poor giving only one cross section for the entire wing and none at all for the tailplane which from the original photos appeared to be totally flat. The unknowns meant a bit of guesswork (and I hate that) and is why it's a rendition and not a scale model.The wing is very fat though - possibly for strength as the Pro was designed to be an out and out aerobatic machine capable of sustaining 5g positive and 4g negative in maneuvers - whatever that means but it sounds impressive.

 

[Jester129]

You certainly do your research and it shows in the outcome. Fantastic work.
No criticism here, but the mounting looks odd from the first picture.
Still love it.

 

[AES]

I don't know all that much about "little" aeroplanes Kittyhawk, but I think the wings on the Citabria I've seen ARE indeed pretty thick. (I understand what I saw is not the version that you modelled though). Thick wings (chord/depth ratio) are for added strength/torsional resistance as you say, and also because at typical little aeroplane speeds, say up to about 120 mph, thick (-ish) wings generally produce more lift and a lower stalling speed. AND, I can't remember, but I THINK I'm right in saying that the Citabria tailplane ("horizontal stabilizer" if you're a Yank) really is more or less a flat plate with just a rounded off LE and TE.

 

[Inspector]

......... but I THINK I'm right in saying that the Citabria tailplane ("horizontal stabilizer" if you're a Yank) really is more or less a flat plate with just a rounded off LE and TE.

That's because they were fabric sewed and doped over the welded tube frame. It is a common construction of many fabric covered light aircraft. I would expect the same occurred on European light aircraft too.

Pete

 

[Kittyhawk]

You certainly do your research and it shows in the outcome. Fantastic work.
No criticism here, but the mounting looks odd from the first picture.
Still love it.

You are right.
I am not happy with the display stands in general and am looking for an alternative to the upright part - it's too much in your face.
Have considered using clear perspex, thin metal tubing etc to make it less obtrusive - I really need to get a good idea here.

 

[Kittyhawk]

I don't know all that much about "little" aeroplanes Kittyhawk, but I think the wings on the Citabria I've seen ARE indeed pretty thick. (I understand what I saw is not the version that you modelled though). Thick wings (chord/depth ratio) are for added strength/torsional resistance as you say, and also because at typical little aeroplane speeds, say up to about 120 mph, thick (-ish) wings generally produce more lift and a lower stalling speed. AND, I can't remember, but I THINK I'm right in saying that the Citabria tailplane ("horizontal stabilizer" if you're a Yank) really is more or less a flat plate with just a rounded off LE and TE.

That's because they were fabric sewed and doped over the welded tube frame. It is a common construction of many fabric covered light aircraft. I would expect the same occurred on European light aircraft too.

Pete

Thank you gentlemen.
Obviously the reason behind the shapes of various parts has no impact on the production of the model - they are just built according to the plans. Even so, you can't help but wonder about the 'why' in certain features and I am very grateful for your input relating to the many technical aspects of the aeroplanes modelled. It adds a most enjoyable dimension to the business and I look forward to more in future.

 

[Inspector]

You are right.
I am not happy with the display stands in general and am looking for an alternative to the upright part - it's too much in your face.
Have considered using clear perspex, thin metal tubing etc to make it less obtrusive - I really need to get a good idea here.

I thought of laser cut sheet metal with your logo but as you make them to suit the display attitude the owner asks for, it wouldn't work. Having custom ones for each model would be too expensive. More head scratching needed.

Pete

 

[Kittyhawk]

You are right.
I am not happy with the display stands in general and am looking for an alternative to the upright part - it's too much in your face.
Have considered using clear perspex, thin metal tubing etc to make it less obtrusive - I really need to get a good idea here.

Actually, as stated in an earlier post I don't like building something where I don't have the information. There is no originality or artistic stuff in me at all and that's the reason why the design of the stands is not very good. I did it. In one instance the child bride designed an angular stand to suit an angular aeroplane - the English Electric Lightning and that one looked good but I can't do that sort of thing. I would really welcome suggestions for a generic stand design suitable for all models.

 

[AES]

That's because they were fabric sewed and doped over the welded tube frame. It is a common construction of many fabric covered light aircraft. I would expect the same occurred on European light aircraft too.

Pete

Yeah, I guess that's right, thanks. As said, I know little about "little" aircraft.

 

[AES]

@Kittyhawk: I don't believe I have an artistic bone in my body, but in my eye anyway, those stands look fine. PERHAPS a little thinner (on the "arm", not the base) would be more in keeping with the smaller types you're modelling, such as the subject of this thread? If you're worried about strength, I guess you could halve the "arm" (in cross-section) and bury a piece of suitably bent piano wire or silver steel inside, using (dare I suggest it?) epoxy.

Just an idea.