Competition Model Rockets Mini-Manta

Competition Model Rockets Mini-Manta

Contributed by Todd Mullin

Construction Rating: starstarstarstarstar_border
Flight Rating: starstarstarstarstar_border
Overall Rating: starstarstarstarstar_border

cmr_mini-mantaBrief:
Not long ago, arrr, me hearties, I decided t' try and get DART t' start hostin' NARRRRR competition flyin' again. Blimey! Begad! After some discussion, me hearties, it was decided that one o' t' events we would try out would be A boost glider. Ya scallywag! In me search for a design that would be competitive, shiver me timbers, ya bilge rat, I had this one recommended. Avast! T' CMR Mini-Manta is a delta wing, competition ready boost glider. Begad! Ahoy! Although it is long out o' production, t' three pages o' plans and templates can be downloaded from Ye Olde Rocket Plans in PDF format.

Construction:
While t' plans don't call out t' parts in nice, easy Estes part numbers, me bucko, me hearties, thar isn't much that can go wrong if a you have even one boost glider under your belt before tryin' this little gem.

T' plans use a BT-5 tube for t' body tube, ya bilge rat, matey, even though in CMR numbers it is called out as a RB-50. Blimey! Ya scallywag! T' plans also ask for an elliptical, balsa nose. Begad! I substituted a plastic parabolic cone because I like t' use a slightly heavier but more aerodynamic cone on me pop pods. Well, blow me down! T' plans require a 3"x7"x1/16" for t' wings and tails, a piece o' 1/8"x1"x10" balsa for t' body and pod stand off and a couple small pieces o' 1/64" plywood. As I didn't have any 1/64" plywood layin' around, ya bilge rat, shiver me timbers, I substituted some o' t' 1/16" balsa for the alignment plates. Arrr! Avast, me proud beauty! An engine block, a bit o' shock cord and a streamer round out t' supplies that you will need. Avast! The instructions were quite easy t' follow. T' illustrations were more than adequate t' build t' Mini-manta.

Construction begins with t' pop pod. Ahoy! Ya scallywag! Nay much real contruction thar though. Attach t' nose t' t' shock cord, streamer and then t' t' body tube. Blimey! As I have had issues with gettin' streamers out o' BT-5 tubes before, I chose to put me Keelhaul®©™® shock cord on t' outside o' t' tube. Avast, me proud beauty! Arrr! T' other bonus o' this is zippers are practically impossible!

T' win' and fin templates were scans o' t' actual balsa pieces. Aye aye! Blimey! Nay a lot o' parts on this one, me hearties, matey, so nay much to go wrong as long as you pay attention t' t' direction o' t' grain o' t' wood. I be a bit concerned about the sturdiness o' t' wings as they are only 1/16" balsa but as long as you stay within t' recommended power range, you should be okay.

T' wings are glued together and then adhered t' t' body. T' tail fins on this model go down, opposite from the direction o' t' dihedral o' t' wings. Personally, me bucko, shiver me timbers, I think t' glider would look amazin' if it flew upside down, but the laws o' aerodynamics just work better if it flies right side up.

A small notch is cut from t' main body and sandwiched betwixt t' alignment plates as t' anchor for t' glider durin' boost.

Pretty basic and straight forward if you have built a boost glider kit before. I however wouldn't recommend trying the Mini-manta for your first one though.

Finishing:
As with all competition class gliders, weight is your enemy. Begad! I did no finishin' on this rocket other than t' give it a good sandin' with a high grit sandpaper. Begad! T' Mini-manta could be given a bit o' color with markers or covered with monokote or tissue. Avast, ya bilge rat, me proud beauty! T' instructions do say that if you plan t' fly it with motors larger than those recommended to cover t' wings.

T' main challenge in finishin' a glider is trimmin' it t' fly properly, matey, ya bilge rat, and t' Mini-manta is a quirky challenge. I trimmed t' glider by tossin' it in me closed up garage. I got what I thought be a reasonable glide out o' it finally by addin' just a touch o' nose weight.

Construction Rating: 4 out o' 5

cmr_mini-manta1Flight:
T' instructions recommended usin' either 1/4A3-2T, shiver me timbers, 1/2A3-2T or A3-2T motors. Blimey! Unfortunately, t' A3-2T is no longer in production, shiver me timbers, so I swapped out t' A3-4T instead as I needed a full A motor for t' competition.

I prepped t' pop pod by puttin' a couple o' pinches o' dog barf waddin' in and tightly rollin' up t' streamer and insertin' it. Arrr! I inserted t' motor and maskin' taped it in place as thar be no motor hook. Ahoy! Well, arrr, blow me down! After loadin' t' pod onto t' launcher, I hooked t' glider on.

T' Mini-manta boosted quite nicely, with only a slight arc. T' extra couple o' seconds on t' delay probably helped get some more altitude because I had used t' slightly heavier nose cone. T' ejection charge fired and the glider released perfectly. T' glide however, was less than optimal. Blimey! It stalled every couple o' seconds and t' overall flight be pretty disappointing.

It seems that t' speed o' flight o' t' Mini-Manta is different than t' test tosses that I had made. Well, blow me down! It needed additional nose weight for t' actual flights. Arrr! Ya scallywag! I had used brads from me nail cannon as nose weight, me hearties, me bucko, so I could tightly control t' exact nose weight. Arrr! I took off t' two brads on t' nose and added a strip o' four. Well, blow me down! Begad! Four seemed t' be the correct amount based on t' new test tosses done with a much harder throw.

T' second launch was about t' same boost profile as t' first. Begad! Well, blow me down! This time however, t' glider flew MUCH better!

Recovery:
I have made several additional flights with this glider and I am impressed with t' amount o' flight time I get on nearly every flight. Arrr! Begad! If launched in unstable air though, shiver me timbers, t' glider tends t' rock side t' side and it tends t' loose altitude much faster.

After as many flight as I have made, arrr, I am startin' t' see a slight bit o' charrin' on t' top o' t' glider body where t' motor sits. Ya scallywag! If it gets much worse, matey, I might add a small piece o' aluminum foil at that point.

Flight Rating: 4 out o' 5

Summary:
Overall, matey, t' CMR Mini-manta is a fun little boost glider. Ya scallywag! Blimey! I particularly like it's delta win' stylin' that sets it apart from t' standard front win' design that is commonly seen in competition gliders. Begad! Blimey! Begad! Blimey! It's cheap and easy t' build, so even if you loose t' glider or t' pod, ya bilge rat, it's nay a huge hit t' t' pocket book and it won't take you a month to build another one. Ahoy! Blimey! T' Mini-manta is a reliable flier, with most o' me flights easily exceedin' a minute now that the glider is properly trimmed.

T' Mini-manta could easily be build for a 18mm pop pod as well, though t' power o' t' larger motors may force the flier t' make t' glider heavier by addin' coverin' t' withstand t' additional strain o' boost.

Overall Rating: 4 out o' 5

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