High Powered Flis Praetor? Will the fins stay on?

Very very nice.

Now to shape the leading and trailing edge. Perhaps a sanding drum on the Dremel will work?

I always start out with hand tools and best intentions, then my impatience rears it's head leading to power tools, then regret soon follows...

THIS is going to be epic...

I’ll stand WAY back though...

Not going to use a router? Going for rounded or airfoiled?

Well if it ain’t ole Jim Flis....I’ll go with ‘Epic’....

No router in the OKTurbo shop. I tried the belt sander / disc sander combo, but no joy. Didn’t look good at all. Ended up using the trusty t-bar sanding stick. At least until my arm gave out and I had to take a break.

The belt sander was great at squaring up all the edges. No good for the LE tapers.

Done with sanding on the fin edges. Started cutting notches and dry fitting the fin can. Working on plans for recovery deployment. Ordered an e-bay from LOC...altimeter...etc. going to try and use the reducer as an electronics bay for dual deploy. Wondering if I even need a drogue chute since these fins are so big and ‘draggy’.

my guess is it'll fall either flat or worse..

Wallace said:

my guess is it'll fall either flat or worse..

Click to expand...

Worse like coming in ballistic? I’ll go with a small drouge in the booster section.

Latest pics. Basic parts dry fitted. Waiting on some parts and material for the recovery system before I epoxy things.

Looks like it "might" become somewhat stable w/out a drogue. One other thing I've noticed is nose cones with canards tend to windmill severely. This kinda has that look to it. Maybe a good ball bearing swivel at the B.T. joint and some way of locking your hardware so it dosen't undo itself?

Got some rocket supplies in the mail today. Started on the electronics bay.





The LOC E-bay is shorter than the transition. Need to find some all thread if I’m not going to have each end recessed.

Quick stop by tractor supply after mother’s day lunch to get 10-24 all thread. Letting the glue dry...



LOC e-bay too short for transition. Cut some longer all thread and added section of tube coupler.




U bolt on to centering ring. Now to get a plan on the rail buttons. Screw into centering rings or drill hole with weld nut on the inside? Usually just screw into centering ring.

A few more pics of the progress. Working on foam board fixture to hold the fin can in place when I start epoxying it all together. Plenty of room in the e-bay.

Brilliant!

I’m not sure how brilliant it is....I’d go more for clever.

The weather has been insane here, but I’m able to get out in the shop for the long weekend. Nothing too exciting. Making up the fixture to hold the fins in alignment. Epoxied the bottom ring then quickly realized I forgot to hammer in the blind nuts...that’ll be tricky. Squared up the balsa fin tip holder spacer things, glued them up and taped onto the fin tips.

Love the jig! Maybe just go with weld nuts (glue type) in lieu?

Many a time when I haven't had 'em on hand I've either cut off or flattened the tabs, then just swiss cheese for glue rivet effect.

I think I can use a c-clamp and sorta press them in...maybe.

Small hammer on the edge of the workbench...no problem. Mixed up a thick batch of west epoxy with colloidal silica and the fins are on. Now wait for the epoxy to cure. Had to improvise with some paint cans to keep it all tight.

So a hammer is truly the universal tool?

So do you guys think I should fiberglass the body tubes? They’re 4” and 3” LOC cardboard tubes. Strong enough? Maybe a layer of thin glass to fill the grooves and give a more durable finish? Don’t want to add too much weight. It has to lane soft with these big fins.

Top ring epoxied on and the 38mm motor adapter is assembled. This the same motor mount LOC uses on the 4” Goblin kit.

Please fly this with a camera!

Even though they won't break, I think the flap-flap will be fun

At only about M/3, I don't think there's too much worry about flutter at this thickness.

I'm sure that mount is big enough to get it over M.3

Went ahead and wrapped a layer of 3oz fiberglass on the lower section. Used a sorta John Coker method....wrapped with thin Mylar instead of Teflon tape.

So you guys are saying that if I keep the velocity below 0.3 Mach I should be OK? I think this thing will go faster than that with a small 54mm J motor. Or should I keep in the H / I range to limit speed and altitude? 0.3 Mach = approx. 337 ft/sec (depends on altitude) correct? I'd like to select motors that give it a "slow" acceleration and long burn....should be easier on the fins aerodynamically and structurally with more gentle changes in momentum.

It will be easier to select motors when I found out how much it will weigh. I'm estimating around 5 to 6 lbs.

Fiberglass turned out good. The Mylar trick worked. Trimmed the end and the couplers came right out. A quick sanding and the edges look really clean. Don’t trust the plastic loop on the nose cone so I’m putting in a ply bulkhead. And a pic of internal fillets on the fin can....tried to be neat.

Time to start thinking about paint scheme. My old mid power Praetor is a WWII fighter plane inspiration...think I’ll go a little more modern on this one. Lots of flat black..maybe grey. let the carbon fiber show on the fins. Stealth fighter...Sketching ideas, but the lettering will be more modern. Jim Flis sent me a digital copy of his logo years ago to use. Not sure how the new owners would feel about me using it.

4” diameter...P4, or P IV...

Any ideas?