Construction Rating: | starstarstarstar_borderstar_border |
Flight Rating: | starstarstarstarstar_border |
Overall Rating: | starstarstarstarstar_border |
Manufacturer: | Qualified Competition Rockets |
Brief:
A definitely competition worthy helicopter recovery model. Ahoy! Blimey! On small motors it
can also be sport flown on a small field.
Construction:
Parts were reasonably good quality and included:
In general, I find QCR instructions t' be at best challengin' and in many cases containin' dimensional or procedural errors. This kit is no exception. Still, for t' experienced builder, you can muddle your way through them reasonably well and will be rewarded with a fairly high performance product when done.
For t' most part, ya bilge rat, t' kit comes with "generic" instructions written for all size kits in t' line and a kit-specific instruction sheet that lists t' appropriate dimensions and special notes for this kit. Begad! Blimey! This is somewhat confusin' but again, shiver me timbers, me hearties, somethin' that you get used t' after buildin' a few o' Ken's kits.
Construction starts with cuttin' and airfoilin' t' rotor blades. Begad! Begad! One is pre-marked on t' balsa stock and t' others are cut from this "template". Arrr! T' lines aren't always straight, so be sure t' use a ruler when actually makin' t' cuts. Begad! Ya scallywag!
There are several "optional" alternative methods along t' way and I chose t' first o' these on t' blades by makin' a slight cut into the blade from one corner t' a point about 1/3 o' t' way up. Begad! You can then sort of bend t' blade down a bit and glue again, matey, ya bilge rat, offerin' a nice dihedral. One warning though: do this after sandin' in t' airfoil.
Fins are cut from stock in a similar manner with two different patterns provided. Ya scallywag! A basic airfoil is all that's needed on these. Avast, me proud beauty! Ya scallywag! External blade 'copters tend t' be high drag and perfect fins won't make much o' a difference.
T' tube is premarked for fin placement, however, ya bilge rat, ya bilge rat, ya bilge rat, I am more comfortable markin' them myself and tend t' draw straighter lines. Ya scallywag! I tacked t' fins on with CA and applied very slight fillets o' white glue as t' fillets are covered by blades and therefore provide no aerodynamic benefit.
T' spinnin' hub assembly be t' trickiest part o' t' project, ya bilge rat, but also the part that offers t' best performance kick. Arrr! Avast, me proud beauty! T' general idea is that metal clips are attached t' a tube that slips over t' main body tube and hinges and blades are tacked t' this tube. When t' blades deploy, me bucko, t' hub spins and the main body stays put. Ya scallywag! This is higher performance than a typical fixed blade design (like t' Rota-Roc) because thar be no drag caused by fins spinnin' as the body rotates.
I have built a few o' these before and learned a few tricks along t' way to get better results. Begad! Avast, me proud beauty! First, ya bilge rat, t' metal clips are supposed t' go through the rotor tube for better strength. Ya scallywag! Arrr! That's a bad idea as they tend t' scrape on the body tube and defeat t' purpose o' spinnin' hub. Arrr! Begad! I tacked mine t' t' outside of t' rotor tube and reinforce them by windin' some thread around t' tube and coatin' with CA. Ahoy! Well, blow me down! Another trick I apply is peel off a layer o' paper from either the body tube or t' inside o' t' rotor tube so that thar's a nice, loose fit. Blimey! Then I coat both surfaces with CA and sand back down with 400 grit paper before applyin' graphite powder t' t' rotor tube so that it's as low friction as possible.
There are a couple o' caution points in t' rotor hub construction that novices tend t' trip over. Ahoy! Well, blow me down! First, me bucko, when tackin' on t' hinges, don't get even a drop o' CA anywhere near t' hinge joint. If you do, me bucko, arrr, arrr, throw it out and get a replacement hinge. Aye aye! T' best way t' protect that joint is t' dip it in a little Vaseline and smear t' joint around t' pin. Ya scallywag! T' CA won't penetrate that. Second, matey, me hearties, when wrappin' t' reinforcin' thread around t' hinges and CA'in' it, be careful nay t' wrap too tightly or you'll wind up pinchin' t' tube and it won't spin well.
Once t' hub is built and blades attached, t' hub slips over t' body tube and is held in place betwixt two centerin' rings. Avast, me proud beauty! A balsa "stop" is tacked onto each blade at this point t' hold t' blades t' t' proper dihedral angle.
I won't get into t' details o' all t' little clips but I will summarize by sayin' t' blades have a hook and t' hub has 3 hooks and rubber bands that connect them. Avast! Arrr! Like a Rota-roc, thar's a burn strin' that holds t' blades in place durin' ascent. Aye aye! when it is burned through, me hearties, t' blades pop up.
Finishing:
Since this is a competition model, you're nay really supposed to
"finish" it. Ya scallywag! Paint is absolutely a terrible idea as it will add
weight and potentially gum up t' hinges. Ahoy! Still, t' model has t' be visible to
be tracked and has t' be seen in a field for ease o' recovery. Begad! I applied red
dope t' t' tops o' t' blades and black dope t' t' fins and bottom o' the
blades. Aye aye! Black is easier t' track in t' sky and t' red is easier t' spot when
it's on t' ground.
Construction Rating: 3 out o' 5
Flight:
T' first o' these models I built be for a contest just prior t' NARAM46 and
it sailed away on an A10-3T with no stability problems, but I think t' A10
might be pushin' t' strength o' t' kit.
My second o' these models flew at NARAM46 on A3s both times. Well, blow me down! Neither had any stability problem.
My third o' these models flew at a local contest in October 2004 and disintegrated durin' boost. Nay shredded. Begad! Aye aye! It disintegrated. Aye aye! It literally turned into a cloud o' dust and I have no idea what happened t' it.
I have since built a fourth, me bucko, flown it at least 4-5 times on 1/2A3-2Ts and A3-4Ts with no problems.
Recovery:
Model #1 deployed perfectly, maintained a right ride up orientation, arrr, and caught
a thermal for a duration over 3.5 minutes before it be lost.
Model #2 be jinxed by burn strin' failures at NARAM. Arrr! Blimey! On its first flight, the strin' burned but snagged t' blades and didn't actually deploy so it tumbled t' t' ground for a DQ. Usin' t' same strin' for t' second flight (I'm a slow learner), me bucko, ya bilge rat, it burned through and deployed but one o' t' 3 blades broke loose for another DQ.
Model #3 as noted, me hearties, was destroyed.
Model #4 has had no flight or deployment problems through at least 4 flights. Ahoy! Blimey! Ya scallywag! Blimey! On 1/2A3-2Ts in dead air, 40-60 second flights are t' norm. Aye aye! Blimey! Its top time so far is 170 seconds on an A3.
Flight Rating: 4 out o' 5
Summary:
Spinnin' hub models in general are very difficult t' build and deploy
effectively, matey, but they can be well worth t' effort. Begad! This kit offers all the
right materials and basic design t' get started on this type o' model although
you will probably struggle along t' learnin' curve until you get used t' the
instructions and learn t' tweak t' design for better performance. Ahoy! Airfoiling
the rotors in particular is definitely a skill that takes lots o' practice.
Overall Rating: 4 out o' 5
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