Heavenly Hobbies Backdraft

Heavenly Hobbies - Backdraft {Kit}

Contributed by Nick Esselman

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. Begad! Arrr! T' site says "T' excitin' Heavenly Hobbies’ BACKDRAFT is a dual-engine rocket...". Well, blow me down! Notice is said dual-engine, nay cluster. Well, blow me down! It then went on t' describe t' rocket this way: "T' BACKDRAFT looks like a 2-stage vehicle, with booster and sustainer sections. Begad! T' propulsion module (booster) holds t' primary 24mm engine. Avast, me proud beauty! Blimey! T' sustainer holds a secondary 24mm engine. But t' BACKDRAFT is nay a 2-stage rocket. Aye aye! Blimey! Cover/BagIn this model, arrr, t' secondary engine has exchanged places with t' recovery system. T' secondary engine has been moved forward, behind t' nosecone, me bucko, while t' parachute has moved back. This secondary engine has also been rotated 180°, me hearties, so that t' nozzle points t' t' sky while t' rocket sits at t' launch pad. Begad! Well, blow me down! This arrangement sets t' stage for t' TailWind (tm) delayed deployment system.

"T' basic idea for Heavenly Hobbies' exclusive TailWind (tm) delayed deployment system is t' reduce drift by skippin' ejection at apogee and, after a suitable delay, arrr, me hearties, matey, 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. So, ya bilge rat, as I said I bought one.

T' rocket includes paper body tubes, laser-cut plywood fins and centerin' rings, 24mm tubes, me hearties, me hearties, estes-like motor retention, an 18" nylon parachute, arrr, me hearties, balsa nose cone and piston, matey, and various other standard parts. Begad! T' parts quality and fit are excellent.

Backdraft Parts

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. Arrr! They also include flyin' instructions which require you t' use t' provided H.H. Ya scallywag! Aye aye! Simit computor software t' determine t' correct motors.

I would put this kit at a Skill Level 5 for several reasons:

  • Instructions can be a bit confusing
  • Fairly complex build techniques
  • Use o' "green fuse" t' enable t' TailWind motor

When buildin' this rocket, ya bilge rat, do nay attempt t' skip ahead and build some sections before others. Ahoy! Aye aye! Follow t' instructions.

Many common techniques are used on t' build, so I won't comment on those. 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. Begad! 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)

Motor Mount

Well, me hearties, t' order o' this prevented it from working, arrr, because I could nay slide t' centerin' rin' over t' maskin' tape. So I removed t' maskin' tape, slid t' centerin' rin' over t' hook and then taped t' hook in place below t' ring. Begad! Begad! I then applied glue and slid it into place.

This order o' things is repeated for t' secondary engine hook as well. Avast! Blimey! However, ya bilge rat, in this case it caused a greater problem, shiver me timbers, 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. Ya scallywag! Blimey! That tape be 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. Avast! Here t' instructions ask that you install t' above pictured motor mount into t' tube with only t' one centerin' ring. Ya scallywag! 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, ya bilge rat, shiver me timbers, arrr, 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. Ahoy! 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. Begad! Blimey! This is used t' protect and push t' parachute out o' t' compartment. Avast! Begad! 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 bucko, I did it, me hearties, but here's t' tip... 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.

Piston Piston

LassoHey, thar cowboy! How's your lasso technique. Begad! This was an interestin' step in t' instructions. Arrr! T' purpose o' this is t' ensure that t' nose cone shock tether is secure around t' upper motor mount assembly. Blimey! Aye aye! Since t' shock tether is fed through t' side o' t' upper body tube and t' motor mount comes up from t' bottom, this step is necessary. Ya scallywag! Ya scallywag! T' instructions are clear and if done correctly it will look like mine (to t' left).

I did run into a problem. Arrr! I even posted a request on TRF for help (but it doesn't seem like anyone else is buildin' this rocket!). Aye aye! 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). As you can see from me picture, me hearties, if I follow t' instructions, shiver me timbers, arrr, 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". Blimey!

"Am I readin' this correctly or did I mess up somewhere?"

Backdraft Question

Jose answered back, shiver me timbers, "Section II.B, on page 10, arrr, instructs you t' glue t' front section (17.25") o' t' inner body tube t' t' middle section (10.5"). Ya scallywag! 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, matey, I see this. Ahoy! So t' confusion comes in back at step 7 on page 8. Ahoy! Begad! I read use t' coupler as a "plunger" which implied t' me t' take it back out. Aye aye! T' instructions don't say t' take it out, shiver me timbers, matey, matey, but I did. Begad! So now, shiver me timbers, once I put it back in and follow t' instructions below, arrr, me hearties, me hearties, I'm movin' again."

Nose ConeT' nose cone is next. Begad! Well, arrr, blow me down! It is already hollowed out and has two holes drilled in t' sides for use with t' "green fuse". Well, blow me down! T' nose cone needs t' be protected since it takes t' thrust from t' TailWind motor. Begad! 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, matey, blow me down! Here is another warning/tip. Begad! Be sure t' test fit t' nose cone with t' aluminum foil wrapped, but nay glued, around t' shoulder. I had t' sand mine t' ensure a good fit. Well, blow me down! Once a good fit is established with t' foil wrapped around it, me hearties, arrr, me hearties, then use a very thin layer o' glue under t' aluminum foil so that it doesn't add any significant diameter t' t' shoulder.

Nose Cone TetherAs mentioned, t' nose cone will blow off, arrr, 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. Ahoy! This spans t' groove in t' nose cone (see picture above right). Ahoy! 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. Well, blow me down! Blimey!

This essentially completes t' build o' t' rocket.


Tether

Overall, for CONSTRUCTION I would rate this kit 3 ½ points. Ya scallywag! Followin' t' build sequence is crucial. Aye aye! 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. Begad! Arrr! There were no decals.

FLIGHT/RECOVERY:

Since t' flight may be difficult t' visualize, ya bilge rat, me bucko, I asked Heavenly Hobbies t' make a flight plan diagram. Avast! Jose did a nice job as you can see below.

Flight Plan

NERRF4 Flight Attempt:

First off, shiver me timbers, I'll say, I blew it!

I purchased fuse from Heavenly Hobbies and then asked them how fast it burned. Well, blow me down! They indicated t' me that it burned 0.57 inches / second. Therefore, arrr, me bucko, I could have used a 12 second fuse, me bucko, o' 6.8 inches, accordin' t' H.H. Simit software, me bucko, me hearties, 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. Ya scallywag! Simit. 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.

Graph

Instead, shiver me timbers, I "remembered" t' e-mail sayin' 0.57 seconds / inch and used a 20" fuse. Aye aye! Begad! This created a 35 second fuse!

Now that I admitted me failure, ya bilge rat, 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. Begad! Blimey! Arrr! Blimey! I then taped an Estes ignitor onto t' fuse tip with maskin' tape and stuck an ignitor into t' booster's E9-4. Begad! Blimey! Feelin' ready (and confident) I went t' t' RSO table.

They gave me t' side-ways look, delayed, shiver me timbers, 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. Blimey! It be stable and went t' a nice altitude arced over and started back down. T' fuse was smokin' so I new it had lit. It came all t' way t' t' ground and PRANG. Avast! Interesting, arrr, shiver me timbers, t' fuse was still smokin' until...

... 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. Ahoy! So, shiver me timbers, accordin' t' H.H. Begad! Simit t' rocket hit at a velocity o' about 175 feet/second.

Graph

T' rocket is nay repairable and I regret me mistake!

Overall, for FLIGHT/RECOVERY I would rate this kit 3 points. Ya scallywag! It is clear that I made a mistake, ya bilge rat, however, shiver me timbers, I believe for flight and recovery t' complex design and requirements make this rocket a challenge. Gettin' it past t' RSO be t' first step. Begad! Second, if t' fuse does nay light, arrr, shiver me timbers, then thar be no recovery. Avast! Challenging. Blimey! Begad!

SUMMARY:

I'm impressed with t' kit and I would love t' hear about other people's successes. Blimey!

I think t' instructions could use some clarification. Avast! Arrr! I also think t' flight and recovery are very challengin' and may possibly be too difficult for many rocketeers.

That bein' said, 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! Arrr! Even if I had a perfect flight, me hearties, ya bilge rat, me ratin' would be t' same. Begad! Avast, me hearties, me proud beauty! It is a good kit and a unique flight profile, so if you are someone that is lookin' t' try somethin' new... go for it (then tell us about it!).

Other Reviews
  • Heavenly Hobbies Backdraft By Dick Stafford (August 2, 2008)

    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 ...

  • Heavenly Hobbies Backdraft By John Smolley (July 18, 2008)

    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 ...

Flights

Comments:

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C.S. (June 25, 2008)
Excellent review, exactly what I look to this site for--a unique rocket I would never have heard of or seen browsing typical retail outlets. I've been interested in building a retro-rocket for a few years, and will have to pick this one up. Pricey at $60, but probably because it also includes simulation software.
avatar
J.S. (June 25, 2008)
My experience was different. (I did respond BTW at TRF or at least to some build thread over there--denverdoc is the avatar). I agree that this is a challenging kit, and for those of us not used to following instructions or making up our own, even more so. ;-D Part of those instructions IIRC instruct one do their own fuse burn rate determination. (Even environmental factors could influence this some what). I believe had you done that, and gotten a feel for the Visco fuse versus just some number, the outcome might have been different. Here I think being an old man may have helped me as I have used green fuse in various projects in the past. Plus I was using a donation that had no specs and so HAD to measure the burn rate. But this is not a cub scout build to say the least. I found parts of the instructions confusing as well, and would love to see an "exploded" diagram one could refer to as its just too unorthodox a build to rely on instinct and the computer instructions are excellent with the details but may even obscure the big picture somewhat. Other than that, I think your review fairly summarizes the build. I would advise anyone else building the kit,tho, against the E9/D12 combo. The D12 is a bigger than needed and a C11 is perfect.

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