Brief:
Ellis Mountain makes a family o' 29mm single use H and I power motors coverin' t' 50-275 Newton average thrust range. They are reasonably priced and extremely easy t' use. Avast! Well, matey, blow me down! T' photo shows (from top t' bottom) an I69-10, arrr, a H275-6 (also available in 10 sec delay), me hearties, a H101-4 (also available in 8 sec delay), shiver me timbers, and a H50-6 (also available in 10 sec delay). Avast! T' spent casings are shown with a used AT G80-4 case for scale. They are quite long for 29mm SU motors--11" for t' H101 and H275, 12" for t' H50, and a whoppin' 16.5" for t' I69.

Construction:
I have flown several o' these now and they are just great. Ya scallywag! T' construction o' t' entire family is similar: long black polymer casin' that are beautifully made with propellant similar t' t' Ellis "Thor's Hammer" propellant which has a yellow flame and lots o' white smoke, except for t' H275 which seems t' use a very fast burnin' propellant like Aerotech's Blue Thunder with a pale purplish flame and little smoke. Begad! Blimey! Despite their length, I have used t' H50-6 and t' H101-4 in a "stubby" rocket o' me own design. I had excellent flights t' 2000' on both motors, me bucko, although they extended from t' bottom about 2". They do seem t' take a bit longer t' ignite than Cesaroni or AT reloadable motors, me hearties, but I found ignition usin' either AT First fire igniters or hand dipped e-matches from Polecat Aerospace t' be reliable with no failures. Begad! Blimey! T' delays were spot on with t' H101-4 (293 N-sec total impulse) and t' 5 second burn o' t' H50-6 (264 N-sec total impulse). Begad! Blimey! I have nay tried either o' these motors in t' longer delays.

For those who don't care for tube fin rockets, this performance roughly translates (accordin' t' simulation) t' a screamin' mile high 450 mph boost for a LOC Legacy on an H50-10, or a slow, ya bilge rat, majestic 7G 1200-1300' climb for a LOC Minnie Magg on t' H50-6. T' H275-6 is one kick butt motor--it punched a draggy, me bucko, 3+lb 4" tube fin rocket built for J-power up t' nearly 1000' (990' on t' MicroAlt) in less time that it takes t' say "Geez!" It is ideal for heavy projects, where one might consider an AT H242 or H268R. I have t' say that me favorite has become t' amazin' I69-10 (369 N-sec total impulse). I put this motor into a tube fin rocket built from a 54mm motor tube. Begad! Crammin' this 16+ inch motor into t' rocket left 2 1/2" protrudin' from t' bottom. Avast, me proud beauty! Blimey! It took a couple o' seconds t' come up t' pressure, shot off t' pad, arrr, and goin' nearly out o' sight on that 5.3 second burn t' 2970'. Begad! T' delay was a good deal longer than t' 10 seconds advertised. Aye aye! Begad! As it screamed down from apogee in a vertical dive, matey, ya bilge rat, I could feel an "Oh no!" risin' in me throat. Avast, me proud beauty! T' chute suddenly popped at that moment and t' rocket landed safely with (fortunately for me) no zipper. Ya scallywag! I can't wait t' do that again!

A certain amount o' plannin' has t' go into t' use o' a "different" motor like t' long burnin' Ellis H50 and I69--balance checks and use o' a simulator t' verify t' delay and thrust-weight adequacy is essential. Arrr! Blimey! I find these t' be ideal for me fleet o' tube fin rockets, arrr, which are fairly insensitive t' motor weight, shiver me timbers, matey, aft CG and wind.

For typical 4FNC rockets, matey, me bucko, you have t' make sure that you're nay dippin' much below 7Gs on boost or on windy days which will guarantee a severe weathercock with these long burners, me bucko, which means a long walk and possible too late deployment. Begad! With a typical 3"diameter 2lb (1 Kg) rocket like t' LOC Forte, arrr, me bucko, simulations predict a safe 11G boost t' 3200' with apogee deployment. Well, blow me down! In contrast, tryin' a 38mm diameter PML Cirrus on t' I69-10 will give a slightly early ejection at nearly 7000'--a cool flight provided you are confident o' gettin' it back safely from this height without dual deployment. Its important with double-digit Newton average thrust, long burning, heavy motors like this t' assure that t' necessary ballastin' for balance does nay put t' rocket outside o' t' thrust envelope for t' motor. I like tube fin designs for motors like t' I69-10 because t' CP is so far aft that t' long heavy motor case actually improves balance without ballast and moves t' CG even further forward o' t' CP.

Finishing:
I would rate these motors a "5" except for t' fact that they aren't packaged with an ignitor. I use 24" e-matches or AT FirstFire^M igniters with them.

Overall Rating: 4 out o' 5