My Experiment: Stiletto 660 Fuselage Conversion & Downsizing for .35-ish Engine

[Kafin Noe’man]

Hi everyone,

I just thought I'd share my next building project.

This is an experimental attempt to convert the Stiletto 660 into a profile fuselage version and scale it down for a .35–.40 size engine. The Stiletto 660 has been one of the models I’ve admired for a long time, but the Walter Umland kit—whether the built-up or profile version—seems almost impossible to find these days.

The idea for this project actually came when I saw the thread by Pat Johnston where he shared his 'tribute' Stiletto 502 plan, which was inspired by the older Stiletto. At first, I thought that I'd just modify the tail section of Pat's plan, but I soon realized the proportion would be way off if I only change that part.

Thus, I downloaded the Stiletto 660 plan from Outerzone and resized it proportionally to match the 502 wingspan. It turned out to be, the overall proportions ended up quite close to the original 660. I also resized the stabilizer and elevator to maintain a similar proportion to the 660’s.

Another modification I made was raising the wing so it's much closer to thrust centerline—the wing center line is now within about 1/2" or less of the engine's thrust line.

As of now, I’ve just finished the laser-cutting the balsa and plywood parts. The total weight for all balsa & plywood components comes out to about 14oz -- seems pretty good number to start with since I plan to put my Enya 35XS at the nose.

Last but not least, I'm really impressed by how Pat designed its wing construction, it's very precise and it should make it easier to build a straight and square wing.

I'm attaching you some progress pictures, and I will keep you updated as the build continues.
Hopefully, the final result can fly well.


Best regards,
Kafin Noe'man

[Paul Van Dort]

The original Stiletto was a 35 size ship. Probably a good reference for you aim.
https://outerzone.co.uk/plan_details.asp?ID=6665

[Ken Culbertson]

I noticed that you are using Pat's airfoil vs the original Stiletto.  It will require more power than a classic .35 but will probably give you better performance.  This is one of my favorite designs.

Good Luck - Ken

[Martin Quartim]

Hi Kafin,

Interesting project.  Did you design it and had the parts laser cut? Seems you are using the Pathfinder airfoil, which is a very good one.

Martin

[Kafin Noe’man]

I noticed that you are using Pat's airfoil vs the original Stiletto.  It will require more power than a classic .35 but will probably give you better performance.  This is one of my favorite designs.

Good Luck - Ken

Yes, you're right.
The wing is using Pat's design, and the fuselage, stab, elevator, rudder are from the Stiletto 660 that I downsized it to match the Pat's wing dimension.
I'm so tempted to try building Pat's wing.

[Ken Culbertson]

Yes, you're right.
The wing is using Pat's design, and the fuselage, stab, elevator, rudder are from the Stiletto 660 that I downsized it to match the Pat's wing dimension.
I'm so tempted to try building Pat's wing.

That airfoil is quite popular in our flying group.  I have used it the past with a slightly more parabolic LE.  I have never been much of a fan of the "pointed" LE, even in the 60's I was using rounded thick airfoils.  Had no clue why, they were just cool. 

Ken

[Kafin Noe’man]

More progress update:

[Kafin Noe’man]

More progress update:

[Kafin Noe’man]

More progress update:

[Kafin Noe’man]

More progress update: