Thanks, Gus.

I've already asked Carl to look into working this fin pattern up, using the earlier fin images. You're right, that small tolerance is really tough just using a #11 blade and a steel ruler. My first prototype is evidence of that. It took me three days, off-and-on, to get a usable set cut by hand. This is still very much a work-in-progress; now Carl will need to look at the new pattern before making a decision. Once we get a pattern that has the rigidity like it needs, a laser-cut set will be easy to do and the parts will fit together much better than my first ones.

Keep in mind, the flight performance is still not confirmed. I need to get a few flights on this one to see if RockSim is right about those open-ended tubes causing such a lot of drag...

"Well, I'm working on it!" -- Mike Myers as Middle-Aged Man

...And much appreciated, too!

Thanks, Carl!

Andromeda Update
 

The first prototype is built and is capable of launch. It may be a few days, though, before I can punch the button as the weather is about to tank here in Mobile. We're expecting rain tomorrow, hopefully late in the evening and not early in the afternoon.

If I get some clear, windless time tomorrow afternoon, I'll try to get Andromeda and Kitfox flown; probably won't get anything else flown.

Hey Craig;

Best of luck; hope the weather cooperates. I'll be real interested in the flight report on the Andromeda. You have an engine in mind that you think will be the best match?

New Plan -- Stratos
 

What a reversal of designs this one is, compared to other recent trends!

This is a simple throw-down design, with good to moderate performance, in the 3FNC category. No open-frame fins, just plain-vanilla slabs with some Snitch-style anglularity. This should be a good one for your everyday "time-filler" flying...

Length: 21.20"
Diameter: 1.04" (ST-10)
Fin Span: 4.04"
Weight: 1.22 oz

A8-3.......244'......Dv 10 FPS
B4-4.......572'......Dv 25 FPS
C6-7......1274'......Dv 27 FPS

All motors reach flight velocity on a standard rod. Reef the parachute shrouds on the "B" and "C" motors for safe recovery.

Note the 2D image this time: It's in Imperial measurements instead of Metric this time! There was a recent update for RockSim, and I think this may have been addressed in the update.

Enjoy!

Photo's Please
 

As you leave the house and you hear a ringing in your ears, don't be alarmed as its just me telling you Not to forget the Camera :D . What we also need hear is an alitiude check to compare that drag thing too :rolleyes: .

Best of luck, JP

James Pierson
NAR# 77907

The B6-4 has the lowest Dv for the IT version, but the B6-2 has good Dv numbers for the RT version. However, using the -2 in the IT version has very high Dv numbers, as does the -4 in the RT version. There is no "compromise" motor that has safe Dv numbers for both scenarios. The wimpy A8-3 might be a good starting point, though, as long as the parachute opens safely.

I think I'll reef a new parachute tonight, just to be safe...

Understood, James! I'll try to wrangle up some help for the session. Pictures of the attempt will be forthcoming...

Andromeda Update, Updated...
 

Folks, I've just noticed a problem that I had not checked on before. As I hold the model in my hand, it feels heavier than it should. Now, I know I'm a bit heavy-handed when it comes to some of my building projects, :o but I've never noticed it as overtly on other models as it is with Andromeda. I also took a look at the balance point for the simulated design, and found the CG should be right at the front tip of the main fins. When I hold the actual model, the balance point is a good 3.5" south of that location. :eek:

The model has the paper-laminate-skin on the fins, and this may be the culprit. I would not have thought the CG would be pulled that far back, though, just from doing this.

Now, according to RockSim this is still north of the CP, but this is in the empty mode -- no motor inserted. I may wind up having to add some nose weight to get the model to fly, and that's going to degrade the performance even more. :(

This means a second prototype will absolutely have to be built, and the weights will have to be monitored closely. I'm going to balance this model at the "dry" location prior to first flight. That will at least remove one issue from the stack...