clolson

My Feedback: (7)

I finally got my H9 80" Cub ARF on the water for the first time. We snapped a bunch of pictures which I have posted at the following link:

http://baron.flightgear.org/~curt/Mo...nt/Hangar9Cub/

(scroll down and click on the collages for a slide show)

I'll attach a couple of the pictures here ...

Regards,

Curt.

freebelle2

My Feedback: (1)

I looked at your photos and they look good. As you say, the tail is high but contrary to your thinking this hinders it from getting off the water. There should be about a 2 degree positive angle of incidence for the wing and the top of the floats. The other thing that needs to be checked is the position of the floats. The step should be slightly behind the CG. If you drop a line from the CG at the wing 8 degrees back from straight down, the step should be at the point that line goes by the bottom of the float. On your plane this would be about 1 1/2 inches back of a line straight down from CG. The plane should taxi up on the step and not with the back of the floats dragging in the water. With the proper setup the plane will fly itself off the water with neutral elevator. Looks as though you have lots of power on the plane. Good luck.

clolson

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Hi Freebelle2,

Thanks for the comments. This plane handled like a dream in the water, tracked straight in the take off run, get's up on step easily, and gets into the air easily. So I'm not too worried about the location of the step. I do want to fix the float incidence mainly for cosmetic reasons, but if it makes it handle even better, than that is just an added bonus. Most of the water taxi pictures were taken with me holding full up elevator and plowing through the water to create as much spray as possible, but if you neutralize the elevator, she does skim along on step quite well. The cub has a 61 2-stroke which is definitely more power than needed. I was worried that the extra weight of the floats would cause wing loading and power issues, but really it was no problem at all. I can get airborne on 1/2 throttle and hold altitude with just a few notches of power ... I guess that's a good definition of way over powered for a cub. :-)

Regards,

Curt.

JimCasey

My Feedback: (1)

Curt,
Full-size Cubs operate with several degrees positive incidence.

Models sometimes need a little less, although I had pretty extreme (5 degrees) incidence with my Telemaster and its water handling was perfect. If the plane starts to veer when you get going fast, you have too much incidence and it is getting up onto the noses of the floats.

ANyway, the floats should never be more nose-up than parallel with the bottom of the wing.

freebelle2

My Feedback: (1)

You're right Jim about the Cub and it's angle of incidence as your photo shows. However if you have flown tandem in a full-size Cub on floats when the two of you are not miniatures and the engine is only 65 horepower you appreciate the extra incidence. You even wish you had wings yourself or extra paddles. The models are usually a higher power to weight ratio so don't need the extra incidence and can create problems as you suggest if too much. You must however have at least level floats or slight positive incidence.

MinnFlyer

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clolson, looks great! is that a lake in Blaine?

clolson

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Hi Mike, this is up at my parent's place NW of St. Cloud a bit. Wish I lived on a lake here in the cities myself ... but then maybe I'd be flying full scale rather than R/C ... :-)

MinnFlyer

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Do you ever go to the TCRC Auction? I'm hoping to find a new Seawind there this year.

clolson

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I don't think I've heard of it. Where would I go to find details? A seawind would be nice, but now that Sig is coming out with a 1/5th scale Waco SRE ARF, I'm finding it hard to think about anything but that ...

Curt.

MinnFlyer

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It's right around the corner from Hobby Warehouse in Richfield. They have it every February. There are some fantastic deals.

Here's an article I wrote about last year's event:

http://www.rcuniverse.com/magazine/a...article_id=666

jimsoque

My Feedback: (2)

CURT-
Awsome job.
The twin rudders rule!
I only used a single, but it's slaved from the rudder, and I used a 101 oz. metal geared servo on the rudder.
Does the ventral fin make that much of a difference?
I take it fromt he photos, that it wasn't too cold up there in MN for your fingers yet, but, nice fall day back on Thanksgiving weekend.
What Float mfg did you use, they look like GP 60 built ups?
I would definitely put in 2 degrees positive in her, but I'm flying at zero, and she breaks water just fine with a Surpass .91 in her.
Your photographer ought to be commended.
My friend shot my photos with his brand new Nikon D camera, second generation camera, at about 1/2000 of a second.
Nice posting.
Happy trails!
Jim

clolson

My Feedback: (7)

Hi Jim,

Thanks for the very kind words. The history of the model is that it was assembled by an older gentleman who unfortunately passed away before he could fly it. His son sold it to a coworker who was interested in R/C. I bought it from the coworker who advertised it online. So I can't take any credit for the very nice job of rigging up the floats and the rudder system. The person who did this originally knew what they were doing and everything is rock solid, works great, and is bullet proof.

Twin rudders: I haven't tried with a single rudder, but with two rudders you are locked into the groove at takeoff. There is absolutely no tendency to swerve if one float comes up on step before the other. Take offs and landings (and taxiing) are basically a no brainer ... tracks a *lot* straighter than with wheels, (One time I tried putting two rudderless floats on a super sportser 40 and never could get both floats up on step at the same time, but this cub is perfect in comparison.)

Ventral fin: I haven't tried to fly without it, but given the smallish "scale" tail surfaces on the cub compared to very stable trainers, I think every bit of surface area back there helps it track and keep more stable in the air.

Temps: I got up to my parents on the last weekend before the lake froze over. The temps were definitely above freezing ... maybe in the high 30's to low 40's. Still was tough getting the engine and my R/C starter to turn over. I ended up borrowing a 12v boat battery and just about killed myself to carry it down to the lake (and back.)

Floats: Carl goldberg super floats. I was a little worried that they would add too much weight, and the thing felt really heavy in my estimation, but it got off the water and flew very easily ... no problems at all. Still very cub like.

Photos: taken with a cheap Canon digital camera ... nothing fancy, but I tried to make some close in passes so the aircraft wouldn't just be a tiny blurry dot.

The lake is now froze over, so I think I'll hang her up until next spring ... unless we get some nice soft fresh snow that would go gentle on the float covering job maybe ...

I have a pair of skis, but I think I'll put those on my Kadet Sr. this winter ... if we get any snow that is.

(Minneapolis, MN)

Curt.

Wayne22

My Feedback: (2)

I had the goldberg floats on mine...worked great...still got the floats, The cub I gave to a buddy in N.Dakota. I flew it with ventral fin most of the time... One time at a big float fly they had an "all cub" fly past...there were 14 of them from 1/3 scale to 40 size. Mine was the only one with the ventral fin, so it was easy to keep track of....