Dorsal Fin or not

[Flydude_54]

Ok,
I have seen several threads about this topic, but have not seen anyone really say if it helps.
I am putting together a 7AC and have decided on using the C85-12, Lasher STC. It is an option on the plane. I like options.
Question is,
1. If I don't put the dorsal fin mod on, what kind of issues will I get into?
2. If I do put the fin mod on, what will I really gain besides weight and an ugly plane? I guess it shows I like the looks of one without.

Alan

[CptKelly]

What would you gain? Power. Did you ever fly a 65hp Champ in the summer, with a load? A C-85 sure makes a big difference in takeoff run, climb, and a little in cruise. A little more fuel burn is the trade off. If you want to keep it light, just don't install the starter or generator. A bare C-85 only weighs a few pounds more than a bare A-65. I wouldn't give it a second thought.

My 2c worth.

Mike

[Nathan K. Hammond]

Sounds like you've got your mind made up Alan.

With out the big tail, it will have a slight tendency to yaw back and forth. You'll probably only notice when in rough air or high power settings. It will have less tendency to weather vane in a cross wind, ergo, a higher crosswind component. It might tend to rotate in a spin a little faster.

With the big tail, you'll have better stability on floats, less yawing back and forth, and it'll look better.

nkh

[WWhunter]

Just curious if some has a picture of both tails and could post them.

[Captgrumps]

Go to Barnstormers.com and click on Antique-Classic and then Aeronca and scroll down and you wil see pictures of both and they are for sale.

Doug

[MikeB]

This is just a opinion, but I think (having flown both big and small tails) that the big tail is a big more stable in the air or you might say 'flys a little nicer'. Large difference....no. Some like the looks of the small tail better as it's more 'orginal', but I don't feel the big tail looks all that bad either.

Mike Berg

[Kalahnikid]

I kinda like the look of the smaller tail, but I can see where it probably adds more stability to the airplane especially at lower speed.

[joea]

I kinda like the look of the smaller tail, but I can see where it probably adds more stability to the airplane especially at lower speed.

Same here. Course anyone watching me fly would not include "stable at lower speeds" in my direction!

[Nathan K. Hammond]

nkh

[WWhunter]

Thanks Nathan!!

[Tim Juhl]

With the lasher STC you can increase the gross to 1300 if you install no bounce oleos and the big tail. That said, the "New" 7EC has the small tail.

I agree with what the other posters had to say but can add that I have the small tail and a C85 that was modified with an 0-200 crank and etc. and am happy with it. The big fin might reduce tail wiggling somewhat but I wouldn't install it on my aircraft when it is time to re-cover the fuselage.
Tim

[Carl Prather]

I'm in the small tail camp. The big tail gives you more avenues to increase the gross weight but the Buzz Wagner 100 horse STC gives the optionand the power all in one package.

When I bought his STC from Buzz, he said the Army made it mandatory for the L-16B because of the low time pilots who would flying them and I suppose it stuck with Aeronca. At the time, I wasn't sure I agreed but I knew I preferred the original tail. Now that ACA has a 1320 lb 7EC flying, it seems that the tail size really doesn't make great deal of difference in terms of safety and that Buzz seems correct in his position after all.

Big tail or small, all Champs and Chiefs are beautiful!

[15A]

I'm in the same situation as Alan. Going from a 65 original airframe to a 90 hp. The covering has 15 hrs. on it. I sure don't want to start cutting it up to add a dorsel fin where as it may not be mandatory. So that's the question. Do I have to put it on??? It's kind of funny, I've flown Cessna 120's, 140's with smaller vertical fins and rudders and bigger motors. Never had an issue controlling the tail. Was the dorsel added because they were increasing the horse power a warping 20-25 horse? Compare that to a Commonwealth of the same era. Now that plane has a huge vertical fin with just a little rudder! Same powerplant. I, too, prefer the look of the small fin, the bigger fin just seems to take away the originality of the Champ. And like Tim says, the new 7EC has the small tail. I'm not looking to cut corners, but if I don't have to cut good fabric, I'd rather not!

[MikeB]

I may be wrong here and I don't have a copy of SL15, but isn't the big tail required when installing a C90? I think you'd be going from a 7AC to a 7CCM (looking at the Lasher book). I agree it doesn't make a lot of sense (big tail). Having said that, I have a friend who owns one, heavily modified with a full dash, electrical, starter, 2 13 gallon tanks. Never flown in it, but he says it will haul a load. Not sure what his useful is, though. I think the CCM goes to 1300 GW which helps some.

Mike

[15A]

Possibly!! I'm still in the planning stage of this conversion. I haven't gotten any paperwork to go by so at the moment, it's all 'hear-say'. Where would I get this SL15???