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. Aye aye! T' site says "T' excitin' Heavenly Hobbies’ BACKDRAFT is a dual-engine rocket...". Notice is said dual-engine, nay cluster. It then went on t' describe t' rocket this way: "T' BACKDRAFT looks like a 2-stage vehicle, shiver me timbers, with booster and sustainer sections. Avast, me proud beauty! T' propulsion module (booster) holds t' primary 24mm engine. T' sustainer holds a secondary 24mm engine. Begad! But t' BACKDRAFT is nay a 2-stage rocket. Well, blow me down! Begad! In this model, t' secondary engine has exchanged places with t' recovery system. Ahoy! T' secondary engine has been moved forward, behind t' nosecone, while t' parachute has moved back. Well, blow me down! Begad! This secondary engine has also been rotated 180°, so that t' nozzle points t' t' sky while t' rocket sits at t' launch pad. Ahoy! This arrangement sets t' stage for t' TailWind (tm) delayed deployment system. Well, shiver me timbers, blow me down!
"T' basic idea for Heavenly Hobbies' exclusive TailWind (tm) delayed deployment system is t' reduce drift by skippin' ejection at apogee and, matey, after a suitable delay, arrr, use a "retro-firing" engine t' slow down t' rocket for deployment o' its recovery system."
Okay, me hearties, shiver me timbers, I get it and it surely sounds cool. Avast! So, as I said I bought one.
T' rocket includes paper body tubes, shiver me timbers, laser-cut plywood fins and centerin' rings, ya bilge rat, 24mm tubes, estes-like motor retention, arrr, an 18" nylon parachute, shiver me timbers, matey, balsa nose cone and piston, and various other standard parts. Begad! 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. Begad! They contain color photo and illustrations t' assist in t' build. Avast! They also include flyin' instructions which require you t' use t' provided H.H. Avast! 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, me hearties, do nay attempt t' skip ahead and build some sections before others. Well, blow me down! Follow t' instructions.
Many common techniques are used on t' build, matey, so I won't comment on those. Avast, me proud beauty! Blimey! On t' other hand, 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! 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. Begad! (picture from t' instructions below)
Well, ya bilge rat, t' order o' this prevented it from working, because I could nay slide t' centerin' rin' over t' maskin' tape. Avast! So I removed t' maskin' tape, arrr, shiver me timbers, slid t' centerin' rin' over t' hook and then taped t' hook in place below t' ring. Avast, me proud beauty! I then applied glue and slid it into place.
This order o' things is repeated for t' secondary engine hook as well. However, in this case it caused a greater problem, me hearties, arrr, 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. Arrr! Blimey! 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. 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 was too much o' a concern for me, arrr, me bucko, matey, 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 was centered. Avast, me proud beauty! Blimey! 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. Arrr! This is used t' protect and push t' parachute out o' t' compartment. Arrr! Ya scallywag! 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, me hearties, I did it, shiver me timbers, but here's t' tip... Begad! Aye aye! Blimey! wet t' first 2" o' Keelhaul®©™ with epoxy, me hearties, CA or white glue first and let it dry completely. Begad! This will make it stiff and then you can push it through without any issues.
Hey, ya bilge rat, thar cowboy! Blimey! How's your lasso technique. Arrr! Ya scallywag! Blimey! This be an interestin' step in t' instructions. Ahoy! Arrr! Blimey! T' purpose o' this is t' ensure that t' nose cone shock tether is secure around t' upper motor mount assembly. Well, blow me down! Blimey! Since t' shock tether is fed through t' side o' t' upper body tube and t' motor mount comes up from t' bottom, matey, ya bilge rat, this step is necessary. Avast, me proud beauty! Begad! Blimey! T' instructions are clear and if done correctly it will look like mine (to t' left).
I did run into a problem. Begad! Arrr! I even posted a request on TRF for help (but it doesn't seem like anyone else is buildin' this rocket!). Arrr! Jose at Heavenly Hobbies responded t' an e-mail requestin' help. Begad!
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). Blimey! 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".
"Am I readin' this correctly or did I mess up somewhere?"
Jose answered back, "Section II.B, on page 10, ya bilge rat, instructs you t' glue t' front section (17.25") o' t' inner body tube t' t' middle section (10.5"). Begad! Begad! If you do that, ya bilge rat, 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. 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. Ahoy! Begad! T' instructions don't say t' take it out, but I did. So now, once I put it back in and follow t' instructions below, shiver me timbers, I'm movin' again."
T' nose cone is next. Avast, me proud beauty! It is already hollowed out and has two holes drilled in t' sides for use with t' "green fuse". Arrr! Blimey! T' nose cone needs t' be protected since it takes t' thrust from t' TailWind motor. Ya scallywag! Avast, me proud beauty! 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. Here is another warning/tip. Ya scallywag! Be sure t' test fit t' nose cone with t' aluminum foil wrapped, but nay glued, me bucko, matey, around t' shoulder. Arrr! Begad! I had t' sand mine t' ensure a good fit. Once a good fit is established with t' foil wrapped around it, me bucko, shiver me timbers, 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, t' nose cone will blow off, so thar needs t' be a tether t' keep it attached t' t' rocket durin' recovery. This is done by attachin' a small piece o' piano wire into t' outside surface o' t' nose cone. Arrr! This spans t' groove in t' nose cone (see picture above right). I don't know about this, matey, 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. Ya scallywag! Blimey!
This essentially completes t' build o' t' rocket.
Overall, for CONSTRUCTION I would rate this kit 3 ½ points. Aye aye! Followin' t' build sequence is crucial. Avast! I personally got confused with some o' t' parts/instruction nomenclature so I believe some improvement could be made. Well, blow me down! T' part fit and quality are excellent. There were no decals. Begad!
FLIGHT/RECOVERY:
Since t' flight may be difficult t' visualize, shiver me timbers, I asked Heavenly Hobbies t' make a flight plan diagram. Ahoy! Jose did a nice job as you can see below.
NERRF4 Flight Attempt:
First off, I'll say, me hearties, I blew it!
I purchased fuse from Heavenly Hobbies and then asked them how fast it burned. They indicated t' me that it burned 0.57 inches / second. Therefore, ya bilge rat, I could have used a 12 second fuse, me bucko, o' 6.8 inches, me hearties, ya bilge rat, accordin' t' H.H. Begad! Simit software, while flyin' on an Estes E9-4 booster and an Estes D12-3 reverse motor.
If all went as outlined, me bucko, t' flight log would look like t' below graph from H.H. Arrr! Simit. Blimey! You can see a flight t' about 650 feet, 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, I "remembered" t' e-mail sayin' 0.57 seconds / inch and used a 20" fuse. Avast, me proud beauty! Blimey! This created a 35 second fuse!
Now that I admitted me failure, me bucko, I'll describe me overall experience:
I was successful installin' t' fuse into t' reverse motor and havin' it held in place with t' toothpicks and maskin' tape. I then taped an Estes ignitor onto t' fuse tip with maskin' tape and stuck an ignitor into t' booster's E9-4. Begad! Feelin' ready (and confident) I went t' t' RSO table.
They gave me t' side-ways look, matey, delayed, ya bilge rat, asked for 3 opinions, and then finally got NERRF's launch director involved who okayed it.
Out at t' pads everythin' set up nicely, 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. Avast, me proud beauty! It be stable and went t' a nice altitude arced over and started back down. Ya scallywag! T' fuse be smokin' so I new it had lit. Blimey! Begad! It came all t' way t' t' ground and PRANG. Begad! Avast, me proud beauty! Interesting, t' fuse was still smokin' until...
... Begad! Arrr! 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. So, shiver me timbers, ya bilge rat, accordin' t' H.H. Aye aye! Begad! 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. It is clear that I made a mistake, however, I believe for flight and recovery t' complex design and requirements make this rocket a challenge. Ahoy! Gettin' it past t' RSO be t' first step. Ahoy! Second, arrr, if t' fuse does nay light, then thar be no recovery. Ahoy! Challenging. Well, blow me down!
SUMMARY:
I'm impressed with t' kit and I would love t' hear about other people's successes. Avast!
I think t' instructions could use some clarification. Ahoy! I also think t' flight and recovery are very challengin' and may possibly be too difficult for many rocketeers.
That bein' said, arrr, shiver me timbers, 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. I thank Heavenly Hobbies for that.
Overall I would rate this kit 3 ½ points. Arrr! Blimey! Even if I had a perfect flight, arrr, me ratin' would be t' same. It is a good kit and a unique flight profile, arrr, so if you are someone that is lookin' t' try somethin' new... Arrr! Blimey! 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)