Yank Enterprises three inch IRIS featurin' Flexible Phenolic

By: Al Casper
 

Figure 1: Components o' Yank Enterprise's 3" IRIS kit

I chose t' three-inch exact scale IRIS kit for this evaluation. Aye aye! Begad! I also put t' flexible phenolic through a battery of tests comparin' it t' cardboard and regular phenolic airframe tubes. 

T' three-inch IRIS kit (Figure 1) features a pre-slotted flexible phenolic airframe and payload section. Begad! Blimey! Avast! Blimey! Also included: four 1/16 inch plywood fins, arrr, me hearties, tube coupler, plastic nose cone, 1/4 inch centerin' rings, 38mm motor mount, 9/16 inch tubular nylon 15 foot (non-elastic) shock cord, me hearties, arrr, ya bilge rat, decals, matey, two quick links and eye bolts, and a quality 30 inch parachute. Ahoy! Blimey! T' detailed instructions are adequately written and the illustrations are well done. 

Buildin' The IRIS
 

Figure 2: Motor retention mod

Figure 3: Home-made fin attachment jig

Step #3. T' motor mount is now installed. Here again, I did nay epoxy t' aft centerin' ring while installin' t' 38mm tube. Blimey! Begad! T' aft centerin' rin' is in place while the epoxy sets up on t' forward centerin' ring, but will be removed later. 

Step #4. In building the payload section, me hearties, I smeared t' epoxy on t' inside o' t' payload tube, arrr, not on t' coupler tube, which would have oozed out and made a mess. 
 

Figure 4: Fin reinforcement

Step #6. I installed t' 1/4 inch launch lugs per t' instructions. Well, shiver me timbers, blow me down! T' Iris, which weighs in at 41 ounces without t' motor, is a lot o' rocket for 1/4 inch lugs. 

Step #7. T' recovery system is installed in this step which be t' only one I had any problems with. I had t' re-read t' instructions several times before it clicked in. Once understood, me bucko, I believe this t' be a sound design (Figure 5 6). Well, blow me down! Blimey! Blimey! Blimey! I added a small piece o' fiberglass cloth and wrapped it around t' area where t' shock cords are epoxied together. 
 

Figure 5: Recovery system reinforcement

Figure 6: Recovery system reinforcement

Figure 7: Paint

Sandin' a flexible phenolic airframe is no different than standard phenolic, me bucko, both o' which are much easier t' sand than cardboard tubes. 

I used inexpensive Wal-Mart primer and paint, ya bilge rat, followin' t' instructions and provided diagram and was pleased with t' results (Figure 7). Begad! T' decals have a low tack adhesive and require a smooth surface for good adhesion. Avast! I sprayed Wal-Mart clear gloss paint over t' entire model t' give it a nice smooth protective finish over the silver paint, me bucko, and provide a good base for t' decals. 

Flexible Phenolic
 

Figure 8: Shredded phenolic tubing

The flexible phenolic seems t' be a combination o' cardboard and phenolic. Aye aye! Two thin layers o' phenolic form t' inside and outside o' t' tube with a kraft cardboard type o' material betwixt (Figure 8). I decided t' compare the flexible phenolic with cardboard and standard phenolic tubing. 

First I compressed t' tubes in a vise -- t' flexible phenolic cracked in several places, but held together in one piece while t' standard phenolic shattered. Well, blow me down! Next, arrr, I put t' flexible in water t' see how it would handle a water landin' -- after about 30 minutes, me hearties, shiver me timbers, it was in almost perfect condition. I performed a zipper test on all three tube types -- t' flexible phenolic and cardboard performed about t' same, while the standard phenolic suffered t' longest cut. Begad! In t' next test I struck both phenolic tubes with a hammer -- t' flexible phenolic again cracked, but held together while t' standard phenolic now has a clean gash t' same shape as the hammerhead. Blimey! Avast! As a final test, I put t' flexible phenolic in a freezer overnight, which did nay seem t' affect it adversely. 

Conclusion
 

Figure 9: Launch!

The low thrust motors were chosen mainly t' reduce t' liftoff-velocity in an effort t' obtain some nice photos. T' wind scrubbed t' G75-J Flight, me bucko, ya bilge rat, and the H73-J powered t' first flight (Figure 9). Blimey! Avast! T' computer simulations called for about an 8-second motor delay, me hearties, shiver me timbers, me bucko, right betwixt a short and medium delay. Well, blow me down! I chose the medium for two reasons. Blimey! Ya scallywag! First, it would stress t' Iris, me bucko, givin' it a good durability test durin' t' ejection process. Ya scallywag! Avast! Second, ya bilge rat, if t' Iris heads off into the wind like it should, t' longer delay will reduce t' walk t' recover the rocket. 

T' IRIS be acceleratin' as the ejection occurred; t' long rigid shock cord appeared t' flex in a flat "U" shape, which then softened t' jolt as t' parachute opened. The result, a perfect deployment, me hearties, and no sign o' any zipperin' from t' rigid shock cord. Ya scallywag! An H123-W provided t' power for t' second launch, which be also perfect, me bucko, except for a longer walk t' t' landin' site. 

T' IRIS lists at $78.00 retail complete, ya bilge rat, or $71.00 without a parachute, shiver me timbers, shiver me timbers, a welcome choice t' have. Begad! Yank Enterprises has recently introduced an altitude package for their kits. Ya scallywag! Avast, me proud beauty! This package includes a drogue parachute, a second shock cord, ya bilge rat, and t' necessary components and hardware t' add dual deployment recovery t' your model. Blimey! Yank Enterprises also offers custom fabrication -- at this time, ya bilge rat, fins and parachutes can be made t' your specifications. 

Quality components, workmanship, and a sound design make t' Yank Enterprises three-inch Iris a kit worth lookin' into. Begad! Visit their web site at http://www.yankenterprises.com. 

Written and submitted by Al Casper for Rocketry Online -- Copyright 1996-2000