Contemplating an SS-7 - Newbie builder

[alandbrooks]

I am about to pull the trigger on a SS7...more likely when I am at Oshkosh. I hear there are some new goodies coming from Kitfox (read that somewhere here)

I have read the manual cover to cover...really like the way it has been laid out and it does make sense.

I have a few questions.
1. Looking for any SS7 builders in the Toronto, ON area.
2. Electrical is my weakest skill, somehow I find it overwhelming at best..yes I have read the Aeroelectric book - sort of makes sense.

1. I am planning on using Vertical Power VPX-Pro purely for the reason of going to 24V - any suggestions if this would be overkill

3. Covering - here I will be going with Stewart Systems

1. Can you mix the systems...ie use Stewart Systems and Polyfibre paint for example.

4. Engine will be either UL Power or Rotax 915 - going to put floats on -any recommendations?

Looking forward to the hearing from the group on whether I have lost my mind or not.

[DesertFox4]

Congrats Alan on your decision to build a Kitfox 7SS.

It will make a wonderful float plane. The 915 should be a great choice for that mission. I'm sure as with new releases of Rotax engines in the past, Kitfox Aircraft will be on the forefront of fitting it to this air frame and designing a comprehensive firewall forward kit for it.

Vertical Power's simplest offering was considered for my build but I ended up unable to justify the price for the less than complicated electrical system I plan to use. Not sure what benefits of running a 24 volt system brings. You may have studied that way more than I.

Paul from Wisc. has discussed in great detail float options and you may want to do a search for float threads and posts. He is our resident float guru and we much appreciate his experience and generosity on our forums. I would love to try a 7SS on floats. Alas, not much water in the desert S.W. for sea planes to play on.
I went with Poly Fiber so no help on the Stewart System. It is gaining in popularity here.

Have you decided on options?
I went with the Laker Leading Edge and the quick build wing options.

Best of luck on your build. Enjoy AirVenture 2016 as I'm sure this one will stand out over all the others for you.
Congrats again Alan.

[jiott]

Electrical was also my weakest skill, but it sounds like you are a reader and you can learn all you need for these simple electrical systems by reading and gathering info from knowledgeable sources. Yes, I think 24v would be overkill; why complicate a basic proven system. Personally I have heard more bad than good about the UL Power engine. The Rotax 912ULS powers many Kitfox float planes, and the turbo 914 or new 915 would surely be a real performer. Definitely don't mix systems in the covering process; however when it comes to just the final color finish coats I am not sure so will let others answer on this.

[Danzer1]

The only advantage I see to 24v is reduced wire sizes and that would be hardly worth it for the amount of wiring in these aircraft. The upside to 12v is availability of tons of EXP instruments & avionics that you probably can't find near as many wide choices in 24v. The other advantage to 12v is many things (if in a bind) can be found off the shelf in an auto parts store.

Personally I have heard more bad than good about the UL Power engine.

Jim, if you have any references, I'd love to hear/see/read them. I've been following the UL 350 series now for years and after you understand their paper ratings (it's the ONLY complaint I've heard and had myself) seems everyone one I've talked to and read about, has been more than satisfied with them. There were some early issues with alternator fans and a recent one for fuel line replacements - no known incidents resulted and all addressed by UL. I've not heard of one complaint about performance/service/reliability. There are more than a few running now particularly on Zeniths and Just Aircraft. Please advise.

Greg

[Av8r_Sed]

Don't sweat the electrical stuff. There are enough of us here to guide you through it. I woulldn't go with the Vertical Power system unless you really needed a dual bus redundant system. With LED lighting and modern avionics you should be able to go with a 12 volt sytem without compromise. These are still basically VFR machines so simplicity tends to rule.

If you're a first time builder, I would tend to favor the majority proven powerplant. Each Rotax engine that's rolled out has had it's own issues to resolve. You don't want to be a pioneer unless you favor tinkering over flying.

[inzersv]

Alan, I am using the VP-X Sport with the 12 volt setup. So far I love it. Electrical scared the heck out of me, but my hangar neighbor (building an RV-14, full IFR) is an electrical guru and helped me get on the right track. He is using the VP-X Pro with 24 volt setup. I agree with the others, use the 12 volt setup for the SS7. I used the Stewart System and loved it except for the painting. I had never painted before, so it was probably just me. The Stewart brothers are great to work with. Back on the VP-X, go to their website and you can print out all of the installation help that you will need. I installed the Dynon SkyView and it works well with the VP-X Sport. Chad Jensen with Vertical Power can answer any questions you may have. His phone is 1(920)216-3699. Good luck with your build.

[jiott]

Danzer, I don't mean to slam the UL Power engine, its just that in my small world I have HEARD more bad than good about it. The bad things had to do with actual power being 10+% lower than advertised, various technical issues which the company is addressing, lack of props available for their somewhat higher than normal direct drive speeds, and more than usual single point failure possibilities. All these issues are argued both ways by various people on several forums and I am not prepared to argue one way or another. IMHO I would be leery because where there is smoke there is quite often fire. Just my opinion/recommendation which is what alandbrooks asked for.

[foxbait]

Hi Allan, I'm in Niagara Falls, started my SS7 build last April, been a slow process so far but you are welcome to come and check things out.
Mike

[av8rps]

I also agree with most of what Greg just wrote.

No one at this time really knows what the 915 will really do. So that really is an unknown. But I'm guessing Rotax did their homework before dumping millions into a new engine.
However, if that 915 is too much of an unknown, a zipper kitted 912s is readily available.

And while I really like the concept of the UL brand engines, so I agree with Greg on horsepower and torque ratings vs the 912-914-915, the Rotax PSRU makes for a much more efficient prop on a STOL or seaplane aircraft. It takes whatever torque you have and turns it into a much higher thrust number than an engine without a PSRU would have.

My best example and defense would be to talk about a 130 hp UL powered Highlalnder that the builder (Steve Dentz -who in my opinion is a master builder) struggled a lot with his to get it to the point it was working well. Ultimately I believe Steve got it really dialed in and it gave him a really good performing Highlander. But yet Steve Henry (The dead stick takeoff guy and friend of Dentz) uses highly modified (up to 145 hp) Rotax 912 and 914 engines on all of his new airplanes that he also competes with in Valdez and Oshkosh. So I believe if he knew the UL was better than the Rotax, I'm pretty sure he would have tried one on at least one of his many builds. And I know he is open minded and always looking for something better as he just tried a 4 stroke 140 hp snowmobile engine in his latest Highlander. But he recently took that out and replaced it with a 912, stating there is a lot more to do to make it a viable alternative to the tried and true Rotax.

With all that said, I would'nt want to discourage anyone from using the UL engine as I think it will work well if you just follow what Steve Dentz did with his. And I also think the Ul will work as good or maybe better than the Rotax if it is used on a faster airframe that requires use of a short prop. But for a STOL type aircraft, I still think the Rotax will perform better overall.

Now if someone would just come up with a PSRU for the UL (and the Jabiru) then Rotax would have some serious competition...

[av8rps]

You will really be happy with a Kitfox. And the Kitfox makes an awesome float plane. The biggest thing is to keep it light if you want an amphib as you'll probably be adding 200-250 lbs of weight to the aircraft for the floats.

If I were building a new Kitfox and intended it to be an amphib I would look for a lightweight covering process that still looks good and is easy to work with. (I like Stewarts and Air-tech, polyfiber is too labor intensive and heavy, unless you use only their polytone product).

I would instrument it with modern electronics over steam gauges for weight savings, as well as for all the additional benefits of more information to the pilot (like synthetic vision).

For an engine? I'd go with Rotax as it is proven again and again the best way to end up with a light empty weight Kitfox. And while the UL engines make decent horsepower, they need to turn a shorter prop to use that power as their rpm's are too high for a long prop to work efficiently (once prop tips get close to going supersonic efficiency plummets...). And since seaplanes always use long props turning slower to make them perform better, the gear reduction on the Rotax is premium. A 914 or the new 915 would be awesome, but a 912uls with a big bore Zipper kit might be nearly as good for a lot less money and complexity.

I too would see no need for a 24 volt system. I also would avoid the extra alternator so many*add to their 912 as it is just more added weight and complexity you can avoid by utilizing led lighting and low draw mfd's in the panel.

With all that said, I will admit I don't always follow my own advice. My little 80 hp 912 Kitfox 4-1200 on amphibs is actually a bit "piggy" (heavy) having really heavy paint, steam guages, carpeting, plexi glass for everything. But yet it performs great. I attribute that mostly to the efficiency of that lightweight 912 making the most prop thrust per pound and per horsepower, all while keeping the empty weight on amphibs under 800 lbs. Obviously a Kitfox Super Sport on amphib floats will weigh more than mine, but i believe if you power it with a 912 series Rotax with 100+ hp you will have great performance too.

Paul Seehafer