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32 Guests On
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REV 2.4 - Sun Sep 20 00:09:43 2009
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| ROCKSIM FILE: | MISSING - please submit here |
| SpaceCAD FILE: | MISSING - please submit here |
| REC'D MOTORS: | Estes: F62-4, G70-5; Pre-Estes: F30-4, G50-7
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 (Contributed
- by Jeff Brundt)
I bought this rocket this past summer as a birthday gift to myself. I finally got around to building it last month. I knew what I was in for when I got it. I had read all the reviews and comments posted on the newsgroup as well as here on Essence. The first thing I did away with was the vacuum formed skins. I prefer not to work with this if at all possible. The nacelles would be hard enough but skinning the wings with this stuff was not an option for me. I bought a piece of 1/64 veneer ply 12”x 24” and this was enough to cover all the flying surfaces. The balsa framework structure is the same as per the plan sheet and the 1/64 ply is the same thickness as the plastic. After assembly the leading edges were then shaped for better aerodynamics.
The next change was how the nacelles were mounted. I heard of the stories of ejection blowing them out and how flimsy the mounting was on landing. To fix this I moved the forward bulkhead to a point just ahead of where the nacelle supports come through the body tube. I used a LOC motor tube coupled to the supplied NCR motor tube to extend to where the forward bulkhead would now be. The nacelle pylons would now go through the body tube and mount directly to the NCR supplied motor tube. This is a very strong mount and makes sure no ejection blowby occurs.
Another weak spot was the joint between the rudder and the horizontal stab. This joint is only a and not very strong since there is minimal surface area to join. Even with an epoxy fillet. To remedy this I used several short pieces of bamboo skewers inserted into the base of the rudder then thru the stab and body tube all the way to (but not thru) the motor tube. This is now a very nice, strong joint.
I did replace the shock cord mount with regular 1/16 aircraft cable since the one supplied by NCR seemed too small for my liking. I needed to add about 8oz of weight to the nose. For this I used copper BB’s and some 30 minute epoxy. This mass is held in place by bamboo skewers cross drilled thru the nose cone tip with the BB’s added then the epoxy poured in. This method is preferable to me rather than using the clay supplied with the kit. The model is balanced to handle up to a H180 motor. The supplied NCR motor retainer was discarded in favor of API’s machined motor retainer (see my Saturn 1b article). The NCR retainer will not work with reloadable motors, which is what I intend to use for this model.
The model is now a true high power bird. After sanding, sealing and prepping I finished the Bomarc as per the diagrams shown in the instructions. The finished weight, without motor, was 44oz. I modeled the flights using win-roc and found the G75-6 and H128-6 were the best suited motors. (the model also flies on AT G64-4 reloads) First flight was on an AT G75-6. The model boosted straight with a slight roll. At apogee it arced over and flew flat for a second or so then the ejection went off and deployed the chutes. The main body came down on a single 36” chute while the nose recovered separately on a 24” chute. I opted not to use the supplied chutes from NCR since my recovery method was going to be two separate pieces. I also used Pratt's 1/8 tubular Kevlar® instead of the NCR supplied elastic. (elastic is a no-no for me now)
In the final analysis, while this is a nice kit and a great size to build, per the instructions and with materials supplied it yields a rocket not quite up to high or mid power standards. To be fair most high power fliers have certain methods and techniques that work for them and kit suppliers cannot meet all those needs. But in my opinion, at the price charged for this kit, (retail $89) there could have been better ways to achieve a fine model without so much extra work. If you can find this kit for a good deal ($40 or less) then I would say buy it and incorporate the mods I made. You will have a nice flying and great looking scale model. I can say it was a real crowd pleaser at our last launch.
As for ratings.......
Construction
3
out of 5 . . . mostly due to vaccu-form
parts and need for mods to improve survivabilty
Flight/Recovery
5
out of 5 . . . excellent flight (keep in
mind to add necessary nose weight for stabilty)
Overall
4
out of 5 . . . I like the looks and impressive
size of this model. However, the user mods required
does not make it suitable for everyone.
![[NAR]](../../images/link_nartitle.gif)
The following excerpt is
from "Sport Rocketry". The intention is to allow guests to get a
basic feeling about a kit. We strongly suggest that you get a copy of the
referenced Sport Rocketry and read the entire article. Inside you will find
many helpful hints in construction as well as other useful information. For
more information, use the two links above.
(Sport Rocketry - May/Jun 1998 - page 30 - by Greg Elder) "The Estes/North Coast Rocketry (NCR) Bomarc is a large scale
model of the real Bomarc missile. . . approximately 1/10 scale. . ."
"Compared to most large model rockets, the Bomarc contains quite a number
of parts."
". . . parts are balsa components and vacuformed plastic used for the
wing, stabilizer, rudder, and ramjets."
"Three plastic centering rings . . . notches are used to hold the engine
retainer during flight."
"The standard NCR Gorilla shock cord mount . . . consists of steel cable
looped through holes in the centering ring and then the ends of the cable are
crimped together using a metal sleeve connector."
". . . 1/2" wide elastic shock cord is tied to the loop on the free
end of the steel cable."
"Several strips of balsa are included in the kit for use in building
skeletons for the wing, stabilizer, and rudder."
"A pattern sheet is included to assist you in cutting the balsa strips . .
."
"The next phase of construction involves gluing the plastic skin to the
wooden skeletons."
"I found construction of the ramjets to be the most difficult
part."
"The plastic ramjet pieces are harder to cut out because of their curved
shape."
"Initially, I could not fit the standoffs into the slots. The slots as
indicated on the supplied marking guide were too short, plus the standoffs were
too wide to fit properly."
"I later received a set of revised instructions from Estes with better
explained how to attach the ramjets to the body tube."
"To complete the Bomarc assembly, two large blocks of clay are added to
the nose cone for correct placement of the center of gravity."
"Two 24" nylon parachutes are provided for recovery."
"The instructions contain a painting guide for the Bomarc."
"Overall, I like the Estes/NCR Bomarc."
The entire article
gives the impression is that it is a slightly challenging kit for the
experienced, patient modeler allowing use of craftsmanship
skills.
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![[Submit your Opinion]](../../images/enter_your_opinion.gif)
GUEST's OPINION:
11/07 -
"I recently picked up a built version of this rocket from a past rocketeer and found that he wrote an article on the build up and flight of the his Bomarc. If you want some good information on what you might do with this vintage kit the article is in the March/April '99 release of Sport Rocketry." (W.B.)
GUEST's OPINION:
01/02 -
"I bought this thing as my first large rocket to build and it was a mighty challenge, especially being fairly new to rockets. I encountered all the problems mentioned by others but I was determined that this thing will look great and fly. If it came out ok I'd be happy to just display it and not fly if flying wasn't possible. Well it came out BEAUTIFUL. It was a pain to build but I've had an experienced L3 Tripoli prefect say that if it was his he wouldn't risk a flight. In his words...it's jut too gorgeous. To ensure a fantastic finish required lot's of work and minimal complaining. It needed lots of epoxy (don't skimp on fillets) and I mean lot's, a bit of filler but not to much, a great deal of paint and spray putty to get it to a perfect finish. Cutting out the plastic was a pain and the ramjets were quite tedious but not insurmountable. Mine has absolutely no gaps or join lines anywhere with a mirror finish paint job. All this of course added to the weight and the thing now weighs about 55oz without case and motor. The cp/cg relation was marginally stable at the start but it could have been due to construction techniques so I needed to add more weight to the nose and it's now ok for H128w reload. Specs say 33oz. See what I mean by maybe not able to fly. I wasn't keen on the way the gorilla/shock cord mounted and may alter that. I replaced the underwear elastic with much wider underwear elastic and about 4 mtrs long to minimize the shock at apogee. I only intend to fly it once (it really does look a picture) otherwise I'd replace the elastic with something more suitable. I'd already mounted the ramjets and am concerned about reports of them blowing off at ejection. Mine have large fillets of epoxy on the inside of the body tub where the balsa protrudes but I will be retrofitting a reinforcement to it to make it stronger. I'll be adding an inner body tube about 30cm long with cutouts for the ramjets supports to protrude thru. this will be thoroughly epoxied in place and the balsa protrusions also generously covered. Because of the extra weight this thing will have it's first launch in march 2002 at Victoria, Australia. It will have to be my level 1 cert on an H128w and if it comes of it should look cool. Because of this extra weight it needs larger chutes/chute. I don't care about drift where this will be launched (I'll be happy to do the long walk as long as it's a successful flight) but I do care about a soft landing. I was going to use three 36in chutes but tangling concerns may require a single 72in chute (that's right... if u saw the finish of it you'd understand the soft landing requirement). If anyone can let me know how successful three chutes are at opening properly I'd love an email. It really would look the part, especially if three hemispherical chutes were used. And if anyone has launched this on a high power engine I'd love to hear from u. My email is at the bottom. In summary it was more tedious than difficult to build and I think the kit is a bit under engineered. It took lot's of finishing materials to get it looking great and don't ask me about the sanding and man there was lot's of that. Be patient with this kit cause if your after a great looking display rocket it's got be up with the best of them. If you want it to fly make sure you glue it together nicely and generously and deal with the weight situation as required. You should have a crowd pleaser on your hands If anyone has a spare complete, not started, Bomarc for sale please contact me. Rudiix@hotmail.com" (R.C.)
GUEST's OPINION:
10/00 -
"Pain in the butt is being kind. I got this kit in a lot as part of a trade; considered auctioning it off. Wish I had. The vacu-forming work is wretched, and all the reviewers' comments about the retention of the nacelles are perfectly right. I formed a small piece of aluminum to the curve of the nacelles, drilled a hole through both, and epoxied a small "hard patch" onto each wing. They were then retained with a piece of ply coming off each hard patch and a screw going through the aluminum reinforcements on each nacelle. Had to do the standard replacement of MMT/ sanding of CR's that is all too familiar to those of us who have built NCR since "the Acquisition". In short, this bird stinks. It is loaded with gaps that there is no reasonable way to get rid of, and after covering them I think it's ugly. Flew okay on an F40-4W, but it is only marginally stable even with a lot of extra nose weight. (In all fairness, this may be due to the mods made on my bird.) Descends pretty fast on the supplied 'chute, too. Breakage on landing is a possible concern due to the flimsy materials, shoddy design, and tiny chute. Mine didn't break because it landed in a swamp filled with long, soft grass. Don't know if I'll dare to fly it again!! IF you must spend the money on NCR, get a Big Brute, Eliminator, or Lance Beta. Avoid this rocket, you'll just end up angry. Living proof that turkeys CAN fly, at least somewhat!!" (D.S.)
GUEST's OPINION:
07/99 -
"Pain in the butt seems to be the credo for this kit. I've built many vacuform kits (static) and this was the pits. The plastic wing skins are terrible. I used a ton of filler for the gaps and still wasn't satisfied with the final results. This and the ramjet mountings need real attention. Given that this is the only LARGE example of the BOMARC (too bad) NCR could have done better." (T.S.)
GUEST's OPINION:
"'Pain in the butt' is the perfect phrase to describe this kit! The vacuform plastic is a fine idea, (cutting it is enough to make you grind your molars smooth) but there is no mention in the instructions about trimming certain overlapping areas to fit the balsa frames. Huge gaps appear where the conduit lines and wing and stabilizer assemblies meet. The instructions say "fill seams with putty". I've used a lot of it. My Bomarc is not complete, and I thank you for the warning about the nacelles making a quick exit at ejection. I'll be laying out the epoxy triple thick. Regardless, it's been a challenge, and I plan to win the battle. It may not have the most perfect skin and finish when I'm done, but she's sure to fly." (J.R.)
GUEST's OPINION:
"This thing was a pain in the butt to build. The biggest problem was the construction of the nacelles, wing, stabilizer and rudder assemblies using the balsa framing and vacuform plastic pieces. Why didn't they just make these complete at the factory using strong but light-weight material? Cutting the vacuform plastic was madness. The model looked beautiful when put together, however, there is a MAJOR design flaw. The nacelles blew out at ejection during its very first flight. The ensuing in-flight explosion also took out a goodly portion of the main body tube (about 12"). I replaced the section with a LOC 3" body tube section and glued the nacelles back into place--this time doubled epoxying both the inside and outside of the nacelle supports into the 12" replacement tubing. I think NCR needs to do some redesigning of this model, because I saw the exact same thing happen to Estes' representative's, Matt Steele, BOMARC at the National Sport Launch in Muncie, Indiana in May. They need to offer suggestions on how to strengthen the nacelle support structures during construction. Otherwise, this is great and impressive model to fly. Crowds love it!" (D.S.)
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![[Enter Rocket Specific Tip]](../../images/enter_a_rocket_tip.gif)
SPECIFIC ROCKET TIP:
08/08 -
" My kit included two sticks of clay. In order to get the Bomarc to the minimum CG recommended for a G77 IN THE INSTRUCTIONS, I had to add two more sticks of clay and some lead fishing weights/epoxy. To fly it with an H128, I had to add another stick of clay to the nose; so, to make this rocket stable, it has to be overweight. Mine has 29mm motor mounts in the ramjets (for G53 blackjacks), and I plan to fly it at a Tripoli event on an away pad, which is the only sane place to pad this thing. Or maybe at a bowling ball lofting event. MOVIE" (J.L.
)
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| Date |
Name |
Motor |
Ejection/ Altitude |
Wind |
Notes |
| 02-09-2008 |
William Beggs |
AT RMS H220-M |
Apogee - Perfect |
0-5 mph winds |
Event: Rio Rancho - Great flight and recovery. Body tube received a small zipper but easily repaired. |
| 09-13-2008 |
William Beggs |
AT RMS H180-M |
Just Past (1-2sec) |
Calm |
Event: Rio Rancho, NM - Great flight. Used two parachutes, one 34 for the booster and one 24 for the nose cone. The parachutes should be one 44 and one 34. |
| 12-11-1999 |
Jeff Brundt |
AT RMS G75-6 |
Apogee - Perfect |
Calm |
- A perfect first flight for the Bomarc. At apogee it attained a flat attitude and then deployed the chutes. A two peice recovery w/no damage. |
| 07-01-2000 |
Jeff Brundt |
AT RMS G75-6 |
Apogee - Perfect |
10+ mph winds |
- A beautiful flight, straight boost despite the wind, N/C chute didn't open but booster recovered fine after long drift and snagging small tree, no damage |
| 10-28-2000 |
Jeff Brundt |
AT RMS G75-6 |
Apogee - Perfect |
10+ mph winds |
- Another perfect flight and recovery. The G75 is a perfect motor. Winds were a bit high but this rocket has proven itself in the wind. No damage on recovery. |
| 05-05-2002 |
Jeff Brundt |
AT RMS G75-5 |
Very Late |
10+ mph winds |
- Launching this rocket in the wind we had was a borderline decision. Flew great though it arced into the wind. Despite the BONUS delay it recoverd with no damage. Ejection was like 10 feet before impact!!! |
| 08-03-2002 |
Casey Kruse |
AT RMS G64-7 |
Just Past (1-2sec) |
0-5 mph winds |
- Great motor for this kit. |
| 08-03-2002 |
Casey Kruse |
AT RMS G64-7 |
Just Past (1-2sec) |
0-5 mph winds |
- Great motor for this kit. |
| 08-09-2008 |
Jeff Lane |
AT RMS H128-4 |
Just Past (1-2sec) |
0-5 mph winds |
- H is minimum, hoping to fly with H and 2 G cluster next time. This was the first time I've seen a Bomarc fly straight up. Some landing damage, easily fixed. Needs bigger chutes. |
| 09-13-2008 |
Jeff Lane |
1x AT RMS H128/2x AT RMS G53 |
Very Early |
0-5 mph winds |
Event: Tripoli/COSROCS Fall Fling - The video looks bad, but there was no damage except the rudder popped on landing. The H128 blew through, and only 1 of the G53s lit. Video at http://www.cosrocs.org/all%20other%20videos/2008videos/9-13-14/lanebomarc.mov |
| 08-26-2000 |
Dave Stout |
AT RMS F40-4 |
Just Before |
0-5 mph winds |
- Oscillated slightly despite added nose weight. Low altitude, descended fast. Disappointing flight, not worth all the work to build & modify!! |
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