Aerotech Deja Vu

Aerotech - Deja Vu {Kit}

Contributed by Dennis McClain-Furmanski

Manufacturer: Aerotech
(Contributed - by Dennis McClain-Furmanski - 12/21/04) (MODS) AT Mirage - Deja Vu

Brief:
Recycled o' bottom 1/4 o' Mirage with different parts and design.

Modifications:
Due t' an unfortunate misunderstandin' betwixt myself and instructions for the Slimline retainer, me bucko, t' Mirage shown here on EMRR (as Mirage Tail cone mod) lawn darted from 800'. Begad! Single use motors require t' spacer rin' with t' Slimline. All that remained intact (in fact, recognizable) was t' bottom 2 feet, the Slimline up through t' first body section. Arrr! Rather than rebuild it exactly, I went off on a tangent.

Two sections o' PML Quantum tube were coupled together t' t' bottom tube and a urethane tail cone added upside down on top o' t' top tube as a transition. Avast, me proud beauty! Begad! T' 1.5" phenolic tube was fitted with a bulkhead, matey, turnin' it into a payload section and this was epoxied into t' 2" transition. Begad! Avast, ya bilge rat, me proud beauty!

T' Mirage is intended t' recover in two pieces, ya bilge rat, arrr, me hearties, top and bottom sections. T' mismatch in sizes isn't much o' a problem, but this bird be way more lopsided with a much larger top. Well, blow me down! Also, ya bilge rat, t' Mirage top half recovers nose down. With this long phenolic payload section I foresaw problems with this. Avast, me proud beauty! I took the advice o' others on T' Rocketry Forum and changed t' recovery profile significantly.

After extendin' t' shock cord with 8' o' additional elastic and 8' of tubular nylon, arrr, shiver me timbers, I tied t' sections together. Ahoy! Ya scallywag! T' chute gets attached just at the coupler at t' bottom o' t' forward section. Begad! Ahoy! This leaves t' tail section danglin' down 10 feet below t' inverted nose o' t' top section. It hits the ground well before t' nose, me bucko, relievin' most o' t' pull on t' chute and allowin' t' top t' descend t' last 10 feet much slower and any drift increasin' so it lands bein' pulled sideways.

(MODS) AT Mirage - Deja Vu Still not content with t' integrity o' t' phenolic, I further strengthened the payload section. Avast! First I wrapped it with 5 layers o' self-adhesive vinyl (also usin' 3M 77 spray adhesive t' beef up t' glue). After lettin' it sit so the glue could cure, me bucko, shiver me timbers, I covered t' tube (and half t' transition) with 2" heat shrink tubin' and held it in t' oven t' shrink it. Ahoy! Arrr! Blimey! I ended up with a 1.75" tube, laminated and rubber coated, strong enough t' support me 215 lbs. Begad! Avast! Blimey! weight. Aye aye! Now when it hits t' ground, matey, matey, me hearties, it'll bounce.

(MODS) AT Mirage - Deja Vu I trimmed off t' heat shrink and fitted t' conical nose. Ya scallywag! There's a bit o' a lip where t' tube has a greater OD than t' nose cone shoulder but it's hardly noticeable at t' scale o' this rocket.

Now weighin' in at 4 lbs, I added rail buttons rather than trust my extended 1/4" rod t' carry this weight. It should still launch fine from the 7.5' long rod given no wind, but no wind is a rarity in Texas. Arrr! Now it can use either.

Construction:
Modification parts list:

  • 2 full length section 2.6" PML Quantum Tube
  • 2 2.6" couplers
  • 1 PML urethane tail cone, 2.6 t' 1.5" (as transition)
  • 1 18" long 1.5" phenolic tube
  • 1 1.5" bulkhead
  • 1 PML 1.5" urethane conical nose
  • 2' o' 2" heat shrink tube
  • 8' o' 1/2" elastic shock cord
  • 8' o' 5/16" tubular nylon shock cord
  • 1 roll 18" wide self-adhesive vinyl
  • Bottom 24" o' an ex-Mirage
(MODS) AT Mirage - Deja Vu

The result is an extremely heavy duty rocket. Blimey! Begad! I believe it could handle almost anythin' short o' another full speed lawn dart.

Finishing:
Heat shrink tube makes an excellent strengthenin' device for phenolic. Avast, me proud beauty! It has a very smooth finish. Aye aye! However, me hearties, bein' made o' rubber does nay allow all paints to stick, and some that do won't dry well. Ahoy! I used white appliance epoxy as a base coat, and a week later it was still tacky on t' tubing. Ahoy! Avast! I later painted the red and gold over it and that dried just fine. Ya scallywag! That was pure luck. You should test first.

T' old finish (a beautiful cobalt blue metal flake with deep clear coat) was simply primed, covered with white appliance epoxy and given a week t' dry. Then it be painted with gloss cherry red, me bucko, me bucko, metallic gold, me hearties, and black appliance epoxy.

Flight:
One other minor mod: I slid two 4" square sheets o' fiberglass cloth down the shock cord before tyin' together, ya bilge rat, matey, t' serve as extra ejection charge protection. Ahoy! T' recovery gear sits right on t' AT ejection baffle, arrr, me hearties, so I felt it needed more.

It hasn't flown yet since t' repair. Begad! At 4 lbs dry, it'll barely reach 500' on a G80. Begad! Luckily I built t' motor mount for t' 11" long Ellis Mountain 29mm H50 and H275 single use motors. As soon as I can get it t' an HPR launch and get an Ellis H50-6, me hearties, it'll get its shake down.

As for t' name, when it lawn darted at a club launch, arrr, it looked hopeless. I'd never seen heavy paper body tube so shredded. Ya scallywag! Blimey! Arrr! Blimey! Blimey! Blimey! Others saw t' mess and said it looked like a write off. Blimey! Blimey! I told them "You'll see it again." And when they do, arrr, they'll see what they saw before. Begad! Blimey! Ya scallywag! Blimey! Blimey! Blimey! Hence, Deja Vu--"seen before".

Recovery:
It also has a 70" Top Flight X-form chute for a slow descent (this chute is rated for 7.5 t' 9.5 lbs rockets by Top Flight) and reduced drift. Avast!

Summary:
Although t' angle isn't as steep as I'd like, t' PML tail cones make for serviceable transitions. Blimey! Aye aye! Blimey! Just use t' entire internal length t' coat with strong epoxy for plenty o' strength because thar's nothin' under it t' take the G forces.

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