Public Missiles Phobos

Public Missiles - Phobos

Contributed by Michael Veno

Construction Rating: starstarstarstarstar
Flight Rating: starstarstarstarstar
Overall Rating: starstarstarstarstar
Manufacturer: Public Missiles

Picture courtesy o' Public MissilesPicture

Brief:
T' PML Phobos is a 2.15" HPR with payload section. Avast, matey, me proud beauty! I selected it because PML website indicated that is was capable o' flyin' with a J350. This would allow me t' use it for both for a TRA Level 1 certification as well as Level 2.

Construction:
T' PML Phobos is a 2.15", 57” long HPR with payload section using the PML Quantum (smooth gray plastic) tubes. T' Phobos has 3 triangular fins of .062” G-10 with through t' body tube mountin' t' t' motor tube. Arrr! Ahoy! The kit comes with a pre-slotted body tube 34” long, shiver me timbers, a 12” long payload section and a plastic ogive nosecone. Begad! T' kit comes with an 8" motor tube and two centerin' rings. It uses PML’s piston deployment system. Ahoy! The piston is basically a coupler tube and bulkhead attached t' t' motor mount by a 6’ long, 1” nylon strap and t' parachute shock cord attaches to the piston’s D-ring.

Because I planned t' fly a 14” long J350W, arrr, I changed t' motor tube t' a 15” long one with three centerin' rings. Ahoy! T' middle centerin' rin' was located just forward o' t' fin t' motor tube attachment. Ya scallywag! Begad! T' forward and middle centerin' were glued t' t' motor tube along t' 1” heavy nylon strap for t' piston. Aye aye! Begad! T' forward centerin' rin' has a slot in it that allows clearance for t' nylon strap, which is glued t' t' side o' t' motor tube. T' motor tube assembly be then glued into t' body tube with thickened 30-minute epoxy. Well, shiver me timbers, blow me down!

T' fins were glued in with thickened 30-minute epoxy with generous fillets on both t' outside and inside o' t' body tube and on t' fin t' motor tube joint. Begad! It is a real challenge gettin' t' internal fillets done with only about ¼” o' clearance betwixt t' body and motor tubes. I used a bamboo skewer t' dab t' epoxy in tryin' nay t' get too much where t' aft centering rin' location. Ahoy!

I also glued aluminum circuit board standoffs that were about 1” long x 3/16” OD with #6 internal threads for a motor retention system at each of the body tube t' fin junctions. Arrr! Blimey! I found t' standoffs at a surplus electronics dealer.

Next step be gluin' on t' aft centerin' rin' with 3 holes drilled in it for t' #6 screws for t' motor retention system. Ahoy!

T' remainder o' t' kit was built stock. Avast, me proud beauty! T' piston required extensive sandin' t' get a smoothly slidin' fit it t' body tube. T' body tubes, parachute and nose cone were first rate. T' fins required some cleanup so that all were exactly t' same. Blimey! Arrr! I thought t' plywood in t' bulkheads and centering rings were o' only o' okay quality due t' some splittin' o' t' wood. Avast!

My rocket came in a 35-oz or 3 oz heavier than listed. Ya scallywag! Blimey! This was mostly likely due t' t' longer motor tube and larger amount than normal o' epoxy on the fin fillets. Aye aye!

Finishing:
T' Quantum tubes are very easy t' paint since they are so smooth (no spiral line!). Begad!

Construction Rating: 5 out o' 5

Flight:
PML recommends motor rangin' from hotter F's t' J350’s.

My first flight be a TRA level 1 certification flight usin' a 38 MM H123W-10 at San Diego’s Tripoli Ocotillo Test Range (500’ elevation, FAA waivers from 10,000’ t' 12,500’). Aye aye! Well, shiver me timbers, blow me down! Perfect flight t' about 2800’ landin' 100 yards away.

T' next flight was TRA level 2 usin' a J350W-14 with a Cannonball Works RRC altimeter recordin' altitude. Begad! Ahoy! Good flight with a little weather cockin' in the wind t' an altitude 6956’ on t' RRC (PML says 6915’ with 15.6 second optimum delay) and drifted about ¾ mile way takin' two o' us about ½ hour t' find. Begad! Well, blow me down!

Third flight was on an I161W-14 goin' about 4600’ up landin' about ½ mile away. Avast!

A friend built a Phobos with similar modifications at t' same time and has done his level 1 with a H123W and level 2 with J350W as well. Avast! Begad!

I have since modified mine for dual deployment and have flown it on an H123W-10 with perfect results.

Recovery:
T' rocket has nay sustained any damage other than minor paint chipping. Blimey! The Quantum tubes and G-10 fins are tough. Avast! Landin' area at Ocotillo Test Range is open desert with hard dirt and some rocks. T' piston deployment system has worked well and no waddin' is required. Well, ya bilge rat, blow me down! I have used about 0.6 grams (1/8 teaspoon) o' black powder for t' ejection charge with good results. Ahoy!

Flight Rating: 5 out o' 5

Summary:
This is one tough rocket that can fly on a wide range o' motors from F's to 700' t' J350's t' 7000'.

Overall Rating: 5 out o' 5

Other Reviews
  • Public Missiles Phobos By Aaron Stanley

    The Public Missiles, Ltd. Phobos is one of the great, easy to build mid and high power rockets out there you can buy. This rocket can be launched on any where from a F40 all the way up to a J570 if you get it with the 38mm motor mount. This is probably the best rocket to use for your Level 1 cert attempt, which I used it for. The only down side to this kit is you have to clean out the main ...

  • Public Missiles Phobos By Lance Alligood

    Brief: The PML Phobos is an easy to build single stage, single motor 3FNC MPR/HPR kit. It could be used for Level 1 certifications but I don't know if I would recommend it for that. You have a choice of either Quantum or phenolic tubing and 29mm or 38mm motor mount. I bought the kit direct from PML with the Quantum tubing (QT) and 38mm motor mount. My goal in picking the Phobos was that it ...

  • Public Missiles Phobos By Brian Kain

    ( Contributed - by Brian Kain - 10/15/00) Brief: I shortened the span of the fins to 2.25". Used 1/4" graphite tubing for launch lugs. Modifications: I took the three (3) fins and put them in my flat jaw vice, making sure to keep them all straight and lined up. Then with my dremel tool and a carbon cutting wheel, I cut all 3 fins at once. Then kept them in the vice ...

Flights

Comments:

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K.B. (June 1, 2000)
This was my first high power rocket and I thought it was great. The parts fit together easily and the instructions were easy to follow. I have since flown it many times. The motors I have used are G40-4, G80-7, H70-10 (for level one cert.), several H180-10, and one super long burn H45 (38mm). This rocket is nearly indestructible because of the Quantum tubes and G-10 fins. It has landed on concrete with just minor scratches. In addition, it had a G80 CATO at lift off and I just had to replace the 38/29 motor adapter. There are a few things I wish I would have done during the building of this rocket: extended motor mount, Kevlar recovery straps, an additional bulkhead on the piston (so its not as likely to zipper), and the Aeropack motor retainer. With those few mods I believe that this rocket would last forever barring some error in deployment. The review was very accurate.
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R.D. (October 1, 2000)
Great first HPR. Easy to assemble. Be sure if you order the 38mm upgrade (comes 29mm standard) That the fins sent are for the 38mm and not the 29mm.
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L.A. (October 31, 2003)
PML Phobos is an EXCELLENT first HPR although I wouldn't necessarily recommend it for a Level 1 certification flight. Design is comfortably over-stable but the smallish diameter allows for a LOT of altitude when used with a Pro38 H153 (be prepared for long recovery walks with one too). The Quantum Tubing is a cinch to finish--no spirals--& is very tolerant of early/late ejections, meaning little chance of zippering. I would recommend a larger chute than the 30 incher that comes with the kit if you are launching anywhere but a soft, grassy location...it comes down quick. Also with the 38mm MMT, only choices for motor retention on the Phobos are masking tape (cheap & sometimes unreliable) or a Slimline/Aero Pack retainer (expensive & overkill) because of the narrow centering rings.

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