Construction Rating: | starstarstarstar_borderstar_border |
Flight Rating: | starstarstarstar_borderstar_border |
Overall Rating: | starstarstarstar_borderstar_border |
Published: | 2010-11-13 |
Manufacturer: | Heavenly Hobbies |
I purchased t' Heavenly Hobbies Backdraft because it sounded really different. Blimey! Blimey! T' site says "T' excitin' Heavenly Hobbies’ BACKDRAFT is a dual-engine rocket...". Avast! Notice is said dual-engine, nay cluster. Avast! Avast, me bucko, me proud beauty! It then went on t' describe t' rocket this way: "T' BACKDRAFT looks like a 2-stage vehicle, with booster and sustainer sections. T' propulsion module (booster) holds t' primary 24mm engine. Ahoy! Blimey! Well, blow me down! Blimey! T' sustainer holds a secondary 24mm engine. Ya scallywag! Blimey! But t' BACKDRAFT is nay a 2-stage rocket. Aye aye! Blimey! In this model, t' secondary engine has exchanged places with t' recovery system. Arrr! T' secondary engine has been moved forward, behind t' nosecone, me bucko, while t' parachute has moved back. Begad! Well, me hearties, blow me down! This secondary engine has also been rotated 180°, me hearties, arrr, so that t' nozzle points t' t' sky while t' rocket sits at t' launch pad. Avast! Avast, me proud beauty! This arrangement sets t' stage for t' TailWind (tm) delayed deployment system. Avast!
"T' basic idea for Heavenly Hobbies' exclusive TailWind (tm) delayed deployment system is t' reduce drift by skippin' ejection at apogee and, me hearties, after a suitable delay, use a "retro-firing" engine t' slow down t' rocket for deployment o' its recovery system."
Okay, I get it and it surely sounds cool. Avast, me proud beauty! So, shiver me timbers, as I said I bought one.
T' rocket includes paper body tubes, laser-cut plywood fins and centerin' rings, 24mm tubes, me hearties, estes-like motor retention, shiver me timbers, an 18" nylon parachute, arrr, balsa nose cone and piston, and various other standard parts. T' parts quality and fit are excellent.
CONSTRUCTION:
T' instructions come on a CD and are printed out on 23 pages o' 8½ x 11" paper. They contain color photo and illustrations t' assist in t' build. They also include flyin' instructions which require you t' use t' provided H.H. Simit computor software t' determine t' correct motors.
I would put this kit at a Skill Level 5 for several reasons:
When buildin' this rocket, shiver me timbers, do nay attempt t' skip ahead and build some sections before others. Blimey! Avast! Follow t' instructions.
Many common techniques are used on t' build, matey, so I won't comment on those. Begad! Begad! On t' other hand, matey, I will comment and provide some warnings/tips for key areas o' t' build.
First warning/tip comes when t' instructions say t' tape (masking) t' motor hook t' t' motor tube. Aye aye! Blimey! T' instructions then said t' put glue on t' motor tube and slide a plywood centerin' rin' over t' hook and up until it stops on t' outward bent forward end o' t' hook. (picture from t' instructions below)
Well, shiver me timbers, t' order o' this prevented it from working, because I could nay slide t' centerin' rin' over t' maskin' tape. Ahoy! Avast! So I removed t' maskin' tape, slid t' centerin' rin' over t' hook and then taped t' hook in place below t' ring. Avast! Begad! I then applied glue and slid it into place.
This order o' things is repeated for t' secondary engine hook as well. Ahoy! However, arrr, in this case it caused a greater problem, me bucko, because one o' t' last steps is t' slide another centerin' rin' down from t' top o' t' rocket (where t' nose cone fits) onto t' secondary engine hook so that thar be room for t' nose cone shoulder. That tape was in t' way and at this point in t' build thar be no way t' remove it!
T' next warning/tip was determined at t' installation o' t' motor mount into t' body tube. Arrr! Here t' instructions ask that you install t' above pictured motor mount into t' tube with only t' one centerin' ring. T' instructions warn you t' "make sure that t' engine mount assembly is aligned coaxially with t' airframe tube." This be too much o' a concern for me, so I made three tabs from scotch tape (PML style) on lower centerin' rin' (the one nay glued in place yet) and slide it in place t' ensure t' tube be centered. Ya scallywag! T' tape tabs allow you t' easily pull t' unglued centerin' rin' back out o' t' tube.
T' fins are through-the-wall mounted fins and thar were no concerns or issues.
T' parachute compartment has a Heavenly Hobbies' EZJect™ balsa ejection piston. Ya scallywag! Avast! This is used t' protect and push t' parachute out o' t' compartment. Arrr! What I found interestin' here is that you are supposed t' push a flimsy/soft piece o' Keelhaul®©™ through a 1" balsa piston with a little bitty hole!
Well, I did it, but here's t' tip... Ya scallywag! wet t' first 2" o' Keelhaul®©™ with epoxy, CA or white glue first and let it dry completely. This will make it stiff and then you can push it through without any issues.
Hey, thar cowboy! How's your lasso technique. Avast, me proud beauty! Arrr! This was an interestin' step in t' instructions. Avast, me proud beauty! T' purpose o' this is t' ensure that t' nose cone shock tether is secure around t' upper motor mount assembly. Begad! Avast, ya bilge rat, me proud beauty! Since t' shock tether is fed through t' side o' t' upper body tube and t' motor mount comes up from t' bottom, me hearties, this step is necessary. Well, blow me down! T' instructions are clear and if done correctly it will look like mine (to t' left).
I did run into a problem. Ahoy! I even posted a request on TRF for help (but it doesn't seem like anyone else is buildin' this rocket!). Aye aye! Arrr! Jose at Heavenly Hobbies responded t' an e-mail requestin' help.
Here's what I wrote: "I'm havin' some trouble here followin' t' illustrations/instructions associated with steps 6 and 7 on part 12.
"This seems t' indicate that we slide t' 10.5" long 24mm tube with t' cap and EZJect into t' middle 10.5" BT50 (one with 3 upper fins). Ahoy! Ahoy! Blimey! As you can see from me picture, shiver me timbers, if I follow t' instructions, me 10.5" 24mm tube will nay be long enough t' reach t' end o' t' 3" couple that is stickin' out by 1.5". Begad! Blimey!
"Am I readin' this correctly or did I mess up somewhere?"
Jose answered back, me hearties, me hearties, "Section II.B, arrr, on page 10, instructs you t' glue t' front section (17.25") o' t' inner body tube t' t' middle section (10.5"). Begad! Avast! If you do that, t' inner body tube will be long enough t' protude past t' coupler in t' F end o' t' middle airframe."
Then it hit me and therefore I replied this way: "Okay, shiver me timbers, I see this. Avast! So t' confusion comes in back at step 7 on page 8. Begad! I read use t' coupler as a "plunger" which implied t' me t' take it back out. Begad! Begad! T' instructions don't say t' take it out, but I did. Ahoy! So now, shiver me timbers, ya bilge rat, once I put it back in and follow t' instructions below, me bucko, I'm movin' again."
T' nose cone is next. Begad! It is already hollowed out and has two holes drilled in t' sides for use with t' "green fuse". Blimey! T' nose cone needs t' be protected since it takes t' thrust from t' TailWind motor. Arrr! T' do this t' inside o' t' nose cone is coated with high-temperature epoxy and t' shoulder is protected with a piece o' aluminum foil that is glued into place.
When t' TailWind motor ignites it will blow off t' nose cone. Well, blow me down! Blimey! Here is another warning/tip. Avast, me proud beauty! Be sure t' test fit t' nose cone with t' aluminum foil wrapped, me bucko, but nay glued, around t' shoulder. Blimey! I had t' sand mine t' ensure a good fit. Ya scallywag! Ahoy! Once a good fit is established with t' foil wrapped around it, matey, then use a very thin layer o' glue under t' aluminum foil so that it doesn't add any significant diameter t' t' shoulder.
As mentioned, matey, t' nose cone will blow off, so thar needs t' be a tether t' keep it attached t' t' rocket durin' recovery. Begad! Blimey! This is done by attachin' a small piece o' piano wire into t' outside surface o' t' nose cone. This spans t' groove in t' nose cone (see picture above right). Ya scallywag! Blimey! I don't know about this, but it is done.
T' tether is then run down t' length o' t' body tube and loosely taped t' t' side o' t' rocket. Arrr!
This essentially completes t' build o' t' rocket.
Overall, arrr, ya bilge rat, shiver me timbers, for CONSTRUCTION I would rate this kit 3 ½ points. Begad! Followin' t' build sequence is crucial. I personally got confused with some o' t' parts/instruction nomenclature so I believe some improvement could be made. Arrr! T' part fit and quality are excellent. There were no decals. Avast!
FLIGHT/RECOVERY:
Since t' flight may be difficult t' visualize, me hearties, I asked Heavenly Hobbies t' make a flight plan diagram. Blimey! Jose did a nice job as you can see below.
NERRF4 Flight Attempt:
First off, shiver me timbers, I'll say, me bucko, I blew it!
I purchased fuse from Heavenly Hobbies and then asked them how fast it burned. Arrr! Avast! They indicated t' me that it burned 0.57 inches / second. Therefore, me bucko, I could have used a 12 second fuse, o' 6.8 inches, accordin' t' H.H. Avast! Simit software, matey, while flyin' on an Estes E9-4 booster and an Estes D12-3 reverse motor.
If all went as outlined, t' flight log would look like t' below graph from H.H. Begad! Simit. Avast! Arrr! You can see a flight t' about 650 feet, me bucko, then fallin' t' about 300 feet, ignition o' t' reverse motor which would brin' t' rocket back t' about 450 feet and then ejection and parachute recovery.
Instead, ya bilge rat, I "remembered" t' e-mail sayin' 0.57 seconds / inch and used a 20" fuse. Blimey! Avast! Blimey! This created a 35 second fuse!
Now that I admitted me failure, me bucko, I'll describe me overall experience:
I be successful installin' t' fuse into t' reverse motor and havin' it held in place with t' toothpicks and maskin' tape. Well, blow me down! Well, blow me down! I then taped an Estes ignitor onto t' fuse tip with maskin' tape and stuck an ignitor into t' booster's E9-4. Avast! Well, blow me down! Feelin' ready (and confident) I went t' t' RSO table.
They gave me t' side-ways look, delayed, arrr, asked for 3 opinions, and then finally got NERRF's launch director involved who okayed it.
Out at t' pads everythin' set up nicely, shiver me timbers, but losin' some confidence I angled t' rocket away from t' crowd just t' ensure that thar would be no incidents.
T' launch time came and t' rocket took off nicely. Ahoy! It was stable and went t' a nice altitude arced over and started back down. Ya scallywag! T' fuse was smokin' so I new it had lit. Arrr! It came all t' way t' t' ground and PRANG. Ya scallywag! Interesting, shiver me timbers, t' fuse was still smokin' until...
... Well, matey, blow me down! t' D12 lit and t' rocket flipped and flopped around on t' ground (bein' substantially crushed) until t' motor finished and 3 seconds later t' ejection charge fired. Arrr! So, shiver me timbers, accordin' t' H.H. Simit t' rocket hit at a velocity o' about 175 feet/second.
T' rocket is nay repairable and I regret me mistake!
Overall, for FLIGHT/RECOVERY I would rate this kit 3 points. Avast, me proud beauty! It is clear that I made a mistake, ya bilge rat, however, me hearties, I believe for flight and recovery t' complex design and requirements make this rocket a challenge. Begad! Gettin' it past t' RSO be t' first step. Begad! Second, matey, ya bilge rat, if t' fuse does nay light, then thar be no recovery. Avast, me proud beauty! Begad! Challenging. Aye aye!
SUMMARY:
I'm impressed with t' kit and I would love t' hear about other people's successes. Arrr! Blimey!
I think t' instructions could use some clarification. Begad! Avast! I also think t' flight and recovery are very challengin' and may possibly be too difficult for many rocketeers.
That bein' said, me bucko, I applaud t' innovation and me experience with this kit has many ideas rollin' around in me head for applications o' t' reverse motor and/or t' fuse ignition. Ya scallywag! I thank Heavenly Hobbies for that.
Overall I would rate this kit 3 ½ points. Avast! Aye aye! Even if I had a perfect flight, me ratin' would be t' same. It is a good kit and a unique flight profile, ya bilge rat, matey, so if you are someone that is lookin' t' try somethin' new... Ahoy! go for it (then tell us about it!).
The Backdraft is a BT-60-based, 24mm-powered rocket that on face value looks like a standard 2-stager. If you've read the previous reviews (and I assume you will before you continue past this intro), you'll know that there is one major difference--the upper motor is used as a retro rocket. Heavenly Hobbies calls this the TailWind delayed deployment system. The upper stage is ignited with a ...
Presented with written permission from RocketyPlanet: Product Review by Dr. John Smolley, MD Wednesday, June 18, 2008 Photo 1: The many, many parts in this kit are of very good to excellent quality Bungee jumping for the fainthearted? The new Backdraft, a BT-60 based three-foot rocket from Heavenly Hobbies, appears ordinary enough ...
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C.S. (June 25, 2008)