When searchin' for me next altimeter, I wanted an altimeter with a few specific functions. Arrr! Blimey! First and foremost, me hearties, I wanted an altimeter that had accelerometer-based deployment for t' first or drogue stage. T' reason I wanted an accelerometer and nay a barometric based unit was because barometric units suffer from atmospheric effects. These effects can cause a late ejection (after apogee) or early ejection due t' Mach effects when a rocket reaches t' transonic region. Begad! Blimey! It is true that most barometric altimeters have a “Mach delay” where you can tell t' chip t' ignore all t' funky readings it may receive from t' sensor for a specific time, but that does nothin' for apogee problems. Blimey! Blimey! Also, shiver me timbers, I would also like t' do some staging/clusterin' and findin' an altimeter that could do these things would be a plus.

Enter t' Pratt G-Wiz LC Deluxe Flight Computer.

I chose t' LC Deluxe because it can do staging/clustering, ya bilge rat, me hearties, deploy a drogue or main chute at apogee (accelerometer based), deploy a main chute at 400ft, ya bilge rat, and record peak altitude. Blimey! Pratt also has t' G-Wiz LC that does nay have t' barometric sensor and does nay provide apogee/main deployment or peak altitude readings.

Some specifics o' t' LC Deluxe are:

• Maximum acceleration: +/- 50g
• Maximum barometric altitude: 35k feet MSL
• Number o' Pyro channels: 3
• Pyro channel functions: 1) Stage/Cluster 2) Apogee deployment 3) Main deployment
• Maximum current per Pyro channel: 8 Amps
• Type o' battery recommended: 9 VDC transistor (However, 12 VDC “N” type can be used)
• Pyro test current: (Usin' 9VDC) 3.5 mA
• Altitude readout: Flashin' LED
• Main battery life: 20 hours
• Dimensions: 3.9” long and .70” wide

When configured for clusterin' (via a jumper) t' LC Deluxe detects and confirms launch. Begad! Ahoy! 0.5 seconds after launch detection and confirmation, Pyro channel 1 fires. Avast, me proud beauty! When configured for stagin' (again via that jumper) t' LC Deluxe fires t' second stage motors (Pyro channel 1) after booster burnout. Begad! Ya scallywag! This is great because you don’t have t' guess when booster burnout will be. After t' staging/clusterin' event, shiver me timbers, t' LC Deluxe then senses apogee and fires Pyro channel 2. If you are doin' dual deployment, matey, t' LC Deluxe will fire Pyro channel 3 at 400 feet.

If you are nay goin' t' stage/cluster, you can use t' LC Deluxe for dual deployment or simple main ‘chute at apogee. Begad! Avast! When usin' only Pyro channel 2 for main deployment, t' LC Deluxe does nay need t' be vented in t' airframe as t' main (Pyro channel 2) charge depends upon t' accelerometer. Ahoy! Begad! However, arrr, you won’t get peak altitude readout.

I recommend usin' t' dual battery set up recommended by t' manufacturer. Begad! Blimey! This way, you have separate power for t' electronics and t' charges. There has been some concern o' power glitches when usin' one battery. Ya scallywag! Blimey! Seems that t' Pyro channels can draw quite a bit o' power form t' unit. Begad! Blimey! For example, ya bilge rat, a DaveyFire N28F can pull up t' 14.1 amps! Blimey! Such and event may cause a power drain t' t' electronics that could lead t' t' LC Deluxe resettin' itself, nay a good thing. Ya scallywag! Blimey! You can also use two “N” type 12-volt batteries instead o' t' 9-volt transistors. This would save some space and some weight.

T' manufacturer recommends nay usin' any type o' armin' switch. Ya scallywag! Rather, they recommend installin' t' batteries t' power up t' unit. Ya scallywag! Ahoy! I do nay like this at all! As an RSO, if you hand me a rocket with an armed altimeter, I will nay be too happy. Well, blow me down! Also, what happens if you must pull t' rocket off t' pad? How will you disarm t' altimeter? I recommend a slide type switch mounted vertically (with t' “On” position bein' down) or horizontally inside t' airframe. Arrr! Avast, me proud beauty! If mounted vertically, make sure t' trim t' tab o' t' switch flush with t' airframe. Blimey! When mounted inside t' airframe, use a small rod or screwdriver t' move t' switch. Don’t use phono jacks! Phono jacks do nay hold up t' g forces at all. They will fail…

T' main fault I have with t' LC Deluxe is continuity. Begad! T' unit only has LED’s for continuity. Ahoy! Ya scallywag! T' check if you have continuity (and if t' unit is even powered up) you must be able t' see into t' airframe and look at t' LED’s. I don’t like this and wish that it beeped out armed state and continuity.

One other problem is that t' main deployment is set t' only 400 feet. This is too low for some flights and can’t be changed by t' user. Ya scallywag! Well, shiver me timbers, blow me down! I’ve heard that Pratt is goin' t' have a unit available with a settin' o' 800ft which is better. Blimey! Aye aye! On me L3 project, ya bilge rat, I am usin' t' LC Deluxe and an Olsen unit. Well, blow me down! Ya scallywag! I will depend upon t' LC Deluxe for apogee deployment (accelerometer based) and t' Olsen for main (which is barometric based and I can set it t' whatever I want).

T' cost o' t' LC Deluxe is $134.95 (the LC is only $89.95). Blimey! Aye aye! Blimey! See: http://www.pratt-hobbies.com/ for more information. Ya scallywag! Arrr! T' people at Pratt Hobbies and Robert Briody are just great t' deal with. Avast, me proud beauty! Oh, me bucko, and thar be a new mail list for G-Wiz users. Ya scallywag! Go t' www.egroups.com and look for t' group G-Wiz.