Nate Ashton's Kitfox SS7

[Nate Ashton]

Alright,


I guess Ill introduce myself. My wife and I are building a SS7 that we picked up at the end of September of 2018. Soooo here's what were working with.



- Kitfox SS7 taildragger
- Aeromomentum AM15 engine
- Oratex 6000 silver and sky blue
- Adjustable rudder pedals
- Lycoming 233 cowlings and firewall
- Spring gear with 850 tires
- Garmin G3X panel


So far I just have videos on YouTube but I'm thinking of posting the details on this forum. So details to come! Below is the YouTube channel link.



https://www.youtube.com/channel/UCoAjOLEe7g0lrkGjbLXz3KQ

[Esser]

Welcome. I'm interested to see how the AeroMomentum engine works out!

[efwd]

Welcome to the group Nate. Yeh, interested as well. Something Different. So tell us, what motivated the decision on that engine?

[Rodney]

Sounds exciting. Their website lists three different horsepower possibilities:

117HP, 131HP and 147HP. Which one do you anticipate using?

The 147HP engine, in the low profile version is listed at $16,000 bucks.
If that works out - WOW!

Are you going to be a "Beta" builder for the Kitfox firewall forward package?

Regards,
Rodney

[jrevens]

Looks real nice, Nate! As far as that little area at the turtledeck mounting tab goes, that should be nothing to worry about. By the time you overlap the top skin, and apply finish tape, it will not be visible. All in all it looks great! I wasn't aware of those specific engines. Your 117 hp unit should perform well. Looks like the TBO is 1500 hrs., and it weighs about 30+ lbs. over a 912 Rotax, but you'd pay a lot for the reduced weight and additional time with the Rotax. In my opinion, that extra weight won't be bad at all, especially if you don't have a heavier controllable pitch prop. Looking forward to your reports!

[bbs428]

Welcome!

Cool looking engine. I did a search and read all about the engine. Very promising!

All the best!

[bbs428]

Just watched your latest youtube update. Cool stuff dude.

I really like that throttle quadrant and the clear access panels. Real slick :)
Looking forward to how your going to mount it. I've been thinking about something similar.
Who did you go with as your avionics vendor? I'm getting ready to jump into the deep end and buy my avionics soon.

Thanks for posting!

[Nate Ashton]

Thanks all for the warm welcome!


EFWD - The initial motivation came from my dad who is building a Long Ez with 2 AM15's, one on each wing. But after getting to researching... Price! and also reasonable performance, readily available brand new parts, great costumer service, familiar modern car technology, options for a turbo in the near future, and it looks cool:)



Rodney - Im going with 117hp low profile. I did have the lower end balanced and blueprinted with the intention of upgrading the top end to run at the higher RPM's for more HP later on. I decided to use Kitfox's lycoming 233 cowling and firewall. Mark (Owner) with Aeromomentum is making the engine mount. John, Debra and team seem pretty busy lately to have a beta builder for a firewall forward package.



jrevens - Thanks for the information on the fabric. I can sleep a little better tonight! As far as props, i'm using a 3 blade Luga 69" scimitar ground adjustable propeller.

[Nate Ashton]

Thanks bbs428, I'm went with aircraft spruce but that's just because I didn't know kitfox was a vendor for Garmin. Other wise would have gone with kitfox. I'm looking forward to how I mount the throttle quadrant as well...

[David47]

Always good to see another builder doing something different. Good luck with the build.

[Mark123]

Welcome Nate!

I am excited to follow your progress. Hoping to pick up some tips. It’s a good time to be a builder with so many chiming in with advice. It’s a very knowledgeable forum. Quite a few projects going on right now at various stages of completion. Thanks for the follow up on the Oratex.

Mark

[Nate Ashton]

Some update photos

[Hawkertech]

I'll be watching this thread another engine to consider for my build, I have a few years. Will it matter what firewall is used?

[Nate Ashton]

Engine mount

Instrument panel

Yes, you will have to use the lycoming firewall. Also, the cowling's will not work. So I have to make my own, should be fun...

[Nate Ashton]

Here's one way to tow your kitfox:/ don't recommend it though. The tail will lift off the ground going down the highway!

[Nate Ashton]

Rib lacing

[Hawkertech]

Yes, you will have to use the lycoming firewall. Also, the cowling's will not work. So I have to make my own, should be fun...
Thanks bummer about the cowling, would have a clue how to custom make one.

[Nate Ashton]

Engine up close

[Nate Ashton]

Interesting throttle

[Hawkertech]

Question on the cowl, is it too short or not tall enough. Or? Just thinking if it could be split and extended/ shortened

[Nate Ashton]

As you can see, its actually pretty close. The spinner location on the Aeromomentum is a bit lower than where the Lycoming spinner location would be. With enough modifying it will work. But their is just enough modifying that I would rather start from scratch and go for an original look. The firewall and boot cowl are per plans and work great.

Its also liquid cooled. So who needs a cowling anyways!

[Hawkertech]

Thanks I guess you could use the existing cowl as a mold starting point. What prop are you using just planning ahead. The only thing that concerns me is the longevity of the engine. Not many in use yet. Also the 50 lbs of added weight in front of cg that will have to be countered.

[Nate Ashton]

I guess time will tell with the longevity. Maybe a glider rating wouldn't be such a bad idea:/ Prop is the Luga 69" ground adjustable. When designing the engine mount, we were able to press the engine much closer to the firewall then the lycoming would be. This brought the CG back to normal. It also meant I didn't have to add any forward sweep to the wings.

[jrevens]

Nate,

That's an interesting looking engine mount design... aluminum? Just curious - did you do any stress or fatigue analysis? Nice workmanship.

[Hawkertech]

That's my other concern, with that heavy engine cantalivered off that mount, with vibration.

[Nate Ashton]

Nate,

That's an interesting looking engine mount design... aluminum? Just curious - did you do any stress or fatigue analysis? Nice workmanship.

Yes, milled aluminum construction. Aeromomentum did the engineering along with the stress/fatigue analysis. It's designed and engineered for continuous 9'gs in all cardinal directions, and 2 to 1 safety factor. I think the wings will come off before the engine does.

[Shadowrider]

Honest question, and not trying to troll. Just curious why you went with aluminum and not steel or chrome-moly? Seems like steel is a better choice for engine mounts to help flex and dampen vibrations? Nice work for sure though.

[jrevens]

Honest question, and not trying to troll. Just curious why you went with aluminum and not steel or chrome-moly? Seems like steel is a better choice for engine mounts to help flex and dampen vibrations? Nice work for sure though.

Nate can answer this for himself, but I just wanted to say that aluminum, in general, can be much more vulnerable to fatigue cracking than steel, which is a serious concern with something usually experiencing constant vibration (like an engine mount). Engine mounts are normally designed to be rigid structures... you don't want it to be flexing, whether steel or aluminum. That's the job of the rubber parts of the structure. And concerning flexibility, aluminum can be very flexible - just think about the spars in our Kitfox wings.

[Shadowrider]

My experience is more with dirt bikes and mountain bikes. An aluminum frame is a lot stiffer than a steel. A steel frame has much more “flex” and dampens vibrations better.

[Nate Ashton]

Honest question, and not trying to troll. Just curious why you went with aluminum and not steel or chrome-moly? Seems like steel is a better choice for engine mounts to help flex and dampen vibrations? Nice work for sure though.

I share the same concerns and appreciate the questions! Long story short, Mark with Aeromomentum has been doing these engine mounts for over 10 years without any failures or indications of fatigue, to my knowledge. He was the most qualified available resource I had to bolt this engine on the plane. But doesn't mean I won't be keeping a close eye! I like to think about the cast engine ears bolted onto bigger conventional engines like the IO540, then bolted to an aluminum airframe with lord mounts in-between. Both materials should work if engineered correctly, I hope. Side note, my previous plane was a piper pacer which needed a new engine mount due to corrosion and zipties chafing through. (That was an expensive annual, thank goodness for experimental!)