7ss vs 7 Speedster differences

[littlecricket]

Saw on Facebook that there was a partially built 7 Speedster for sale. I would like a Super Sport, but I’m wondering what the differences are? And, if it can be converted to a Super Sport. Thanks.

[AirFox]

They clip a bay of the wing for the speedster, add a bunch of fairings and have the airfoil struts and gear. The 7 wing is going to be a better all around wing unless you want aerobatics.

[efwd]

Really? Didn't the SS7 speedster just come available in Aug after that airframe option was announced at Airventure 2017? I would think that that option would just now be available for delivery let alone partially built. That's fast.
Eddie

[Esser]

You can modify your kit to become a speedster.

[littlecricket]

So, if I understand this. The biggest differences is the clipped wings. So, if it has regular Super Sport wings and then having the rest of airplane “Speedster” that won’t effect the characteristics that it’ll fly like a Super sport, right?

[Dusty]

The speedster appears to have no dihedral which would be hard to change.I'm curious to why the difference and if anyone has flown with both options good or bad or indifferent?

[Esser]

The big thing is if he modified the kit to be a speedster find out if he clipped the wings already. If it’s Jasons, it looks like the wings haven’t been touched yet so dihedral will not have been set yet. The speedster also has new aero dynamic grove gear, Jason’s has cabine gear. Everything in the speedster is generally to clean it up. No major changes except the clipped wing.

[littlecricket]

The big thing is if he modified the kit to be a speedster find out if he clipped the wings already. If it’s Jasons, it looks like the wings haven’t been touched yet so dihedral will not have been set yet. The speedster also has new aero dynamic grove gear, Jason’s has cabine gear. Everything in the speedster is generally to clean it up. No major changes except the clipped wing.

Yeah, that is the one I’m looking at. It looks like a nice build so far, but timing may be wrong for me. I was planning/budgeting for a late spring purchase, so I don’t think I’m in his ballpark. Plus, transporting across country from Chicago in the winter doesn’t sound fun. But, I’m still thinking about it... 😁

[Esser]

Yeah, that is the one I’m looking at. It looks like a nice build so far, but timing may be wrong for me. I was planning/budgeting for a late spring purchase, so I don’t think I’m in his ballpark. Plus, transporting across country from Chicago in the winter doesn’t sound fun. But, I’m still thinking about it... 😁

It really looks like a great deal. Lots of labour is completed as well as some discount on parts. If I were in your shoes I’d try to make it work!

[aviator79]

The estimate from Kitfox is included in his pictures, but with the prices conveniently left out of the frame. It looks like a standard kit, but with some speedster options added. Also of note is that it is missing some pieces (wind screen and doors), but appears to come with others (cowls). Since his email address indicates he's from dream schemes who designed the paint for the factory Speedster, he probably had an early line on the Speedster mods, and may have been in a good position to work out a bargain. The $29k price he got may already include a bit of a discount from Kitfox as the streamlined lift struts are a $3500 option on their own. With the additional discount he's offering, plus the completed work, this looks like a pretty good deal. If I didn't have my own kit arriving in a couple weeks...

[HighWing]

The speedster appears to have no dihedral which would be hard to change.I'm curious to why the difference and if anyone has flown with both options good or bad or indifferent?

I have a buddy that used to have a Model IV with dihedral that he said reminded him of a diving pigeon. He hated the look. When I was building my first IV I asked the factory the difference in performance since the early IV Speedster also had no dihedral. I was told - no difference. I reduced the dihedral, but did not eliminate it. Then recently I read an article in Kitplanes Magazine discussing "Dihedral Effect". Essentially, Wing dihedral is critical in low wing airplanes, but not so much in high wing airplanes. With a high wing a side slip will create high pressure under the up-wind wing due to the fuselage being below the wing and low pressure under the down-wind wing for the same reason resulting in a favorable roll tendency. This effect is missing (actually potentially reversed) with a low wing airplane. This necessitating dihedral on low wing airplanes. My first IV had minimal dihedral as I built it from day one. The one I fly now had the wings installed by the first builder and somewhat resembles the diving pigeon. With my two Model IVs, I perceive no difference in handling.

[Av8r3400]

Lowell, what about speed?

Was the plane with minimal dihedral any faster?

[HighWing]

The speed of the second airplane even with more fairings, is a bit slower than the first. Not sure the specific reason as there so many factors to consider. I sort of feel, though, it is because of the empty CG first vs. second - explained in the "Zipper Big Bore" thread. I should mention that the second airplane is lighter than t he first by 35 lbs.

[jrevens]

The speed of the second airplane even with more fairings, is a bit slower than the first. Not sure the specific reason as there so many factors to consider. ...

Do you think it might be largely attributable to the landing gear, Lowell?

[HighWing]

That is a reasonable thought. The cabane gear is dirty despite the gear legs being faired. By coincidence, I am working on the feasibility of wheel pants, or rather the half wheel pants as seen on some Aircoupes. Along with that, a fairing around the brake calipers and gear leg to wheel pant with fairings on all cabane and spring strut tubing. We'll see. Last fall I faired a friend's cabane gear. No word on that because the Avid Mk4 has yet to fly.

[Av8r3400]

My old Kitfox had the faring on the radiator. The Mangy does not. I believe this to be an area of increased drag, too.

[av8rps]

So...if Lowell's old faster airplane weighed 35 lbs more but had a spring gear and no dihedral, verses the slower, later but lighter and better faired out airplane with a cabane gear and dihedral, unless the CG difference is substantial, it's reasonable to think that it is either the gear or the dihedral making it faster. I personally think the no dihedral is more of an advantage for speed.

I believe the dihedral is the bigger factor because my 912ul Kitfox 4 on amphib floats is faster than many Kitfoxes on wheels. And those 14 ft long 230 lb floats have got to be draggier than any landing gear, right?

With that said, I still am a firm believer that having more wing underside false ribs is a big factor in whether or not you will have a fast Kitfox or not. Without the extra false ribs at higher speeds the airfoil tries to revert back to the older undercambered airfoil, which is a significantly slower wing than the riblett airfoil.

I'm pretty confident if you put 4 underside false ribs between each rib, removed the dihedral, and then faired out everything you reasonably could, the landing gear wouldn't have a huge impact unless you went with large bush wheels.

[HighWing]

Lots of good thoughts and good ideas. Yes, Larry, I do think the fairing around the radiator helps. I think of that a lot as well. Another thing not yet mentioned is prop pitch. That is one thing I have not played with with the new airplane. A local guy with the in flight adjustable IVO claims speed performance that I will only be able to match with a significant compromise in climb. Right now I am still in the fairing mode with lots planned. The pictures are early in the half wheel pant project. Right now it is to just see if it is feasible. The mounting will be the real test -- but fun.

What I call the fairing Liner
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The original Wheel Pant stretched to fit the larger tire diameter
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