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Fred22

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Well folks this is my first stab at a real build thread especially in MPR. My chosen victum is the HAWKS HOBBY BOMARC. Please do not judge the value of this fine kit by my efforts. The nosecone is superb. The ramkets speek for themselves. You actuaaly make cuts in the mbt to recess the wing. The cut out bits are the used to make the body aerodynamic again :) My cuts need work :)

label.jpg


ramjets.jpg


lots of parts on sloppy hobby table.jpg


nosecone.jpg
 

Fred22

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In case anybodys surprised Gordon I have already contacted excelsior about custom decals :)
Cheers
fred
 

sandman

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In case anybodys surprised Gordon I have already contacted excelsior about custom decals :)
Cheers
fred
Doesn't the kit come with decals?

OH, you probably want the John Diefenbaker version. eh..:rolleyes:
 

Fred22

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Doesn't the kit come with decals?

OH, you probably want the John Diefenbaker version. eh..:rolleyes:
Of course eh :) Ya it does Gordon and I will have shot of them later :)
Cheers
fred
 

dpower

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...You actually make cuts in the bt to recess the wing....
And that makes this the best kit I've seen of the Bomarc; I look forward to your review. How much nose weight is included for this beast?
 

dcastle

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So where do I find one of these kits? Not to bring up a very sore subject but I wouldn't mind building something on the scale of the large Bomarc I'd ordered from Empire a few years ago that never appeared in the mail....this looks to be about right...
 

Fred22

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And that makes this the best kit I've seen of the Bomarc; I look forward to your review. How much nose weight is included for this beast?
About 180 grams on my rather cheap postal scale :)
 

Fred22

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So where do I find one of these kits? Not to bring up a very sore subject but I wouldn't mind building something on the scale of the large Bomarc I'd ordered from Empire a few years ago that never appeared in the mail....this looks to be about right...
Try Red Arrow
http://www.redarrowhobbies.com/
It's where I got mine :) I have always found their service to be outstanding :)
Cheers
fred
 

Fred22

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Well guys did a number of things tonight. First off I marked and cut the conduit tube. basically using one of the handy dandy guides provided I marked and cut it in half :) The nosecones which form conduit ends were also cut in half. I had to notch one for the tail and I put my tamiya putty next to it as I suspect I will need some :) Also they leave the method of engine retention up to the builder. I have a hook which maight be big enough but I would apreciate some aopinions. Also can you friction fit a 29mm motor?
Cheers
fred

conduit and conduit ends cut.jpg


conduit cones precut.jpg


conduit tail end.jpg


conduit tail end marked precut.jpg
 

Fred22

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Heres a few more pictures :) Is the hook long enough fellas and if it is how much overhang do I need from the bottom of the tube ?
Cheers
fred

conduit with guide.jpg


engine rings.jpg


engine tube.jpg


possible engine hook.jpg


nose cones in half.jpg
 

Pantherjon

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Looking good! The hook you have is too short for the 29mm hobby line case(29/40-120) which is 5 inches long..Looks to be an Estes 'E' hook..Yeah you can do friction fitting on 29mm motors..Personally I would put in some PMR(Positive Motor Retention) if you plan on flying it on reloads..It's a real bummer to have a perfect flight only to find when you retrieve the rocket you have lost the motor casing..
 

Fred22

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Thanks John I will look into getting a hook and an engine block :)
Thanks
Fred
 

Fred22

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Guys who sells motor hooks and engine blocks for 29mm?
Thanks
Fred
 

Fred22

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Well guys I just had a look at a great book I got at apogee called "Model Rocket Design and Construction". To my chragrin I found out hooks aint used on the MPR's and they dont need an engine block because they have a lip that potrudes arond the bottom of the motor mount tube. Instead one way to retain the motor is to use two pieces of hardwood and a couple of screws to kep the motor in the tube. brilliant idea :)
Cheers
fred
 

cjl

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Yep, or if you like a really solid solution, you can get an Aeropack engine retainer. They're somewhat expensive, but the quality is worth it.

You don't need an engine block though - you can use motors of varying lengths in 29mm for everything from a smallish F motor (or even a large E) to a smallish I motor.
 

Fred22

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Yep, or if you like a really solid solution, you can get an Aeropack engine retainer. They're somewhat expensive, but the quality is worth it.

You don't need an engine block though - you can use motors of varying lengths in 29mm for everything from a smallish F motor (or even a large E) to a smallish I motor.
My biggest problem with mpr is the fields I use up here are small for LPR let alone MPR so I have to figure out an optimal size somehow :)
Cheers
Fred
 

Fred22

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Well two steps forward and one backwards today :) First I have a picture of the motor moubt tube before it was put in. Notice the centre wing has a a flat side for the wing to sit on. That becomes more important as we move on:) I also notched a centreing ring and put a kevlar string on for recovery :)

motor mount tube before insertion.jpg


end ring with notch.jpg


ring with kevlar.jpg
 

Fred22

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Next came inserting the motor mount tube into the main body tube and notice the forward ring was not flush with the forward end of the opening :(

gap closeup.jpg
 

Fred22

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I obviously had made a mistake with the opening I had created. After all the motor mount tube was flush with the end of the main body tube. If the wing was to sit flush with the openning something would have to be done. I proceeded to enlarge the opening at the opposite end and use the piece as a patch to seal the other. Hope I got this right and thank goodness for putty :)

tube open with patch.jpg


closeup tube with patch.jpg


tube fix.jpg
 

Pantherjon

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Nice recovery! And I am sure with the putty, as the finish gets closer, that patch won't even be visible! ;)
Maybe even a wrap of light(3oz?) fiberglass to further strengthen it a bit too...
 

Fred22

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Nice recovery! And I am sure with the putty, as the finish gets closer, that patch won't even be visible! ;)
Maybe even a wrap of light(3oz?) fiberglass to further strengthen it a bit too...
Thanks :) The fibreglass sounds good as I have never worked with that before either :) John how big a screw do you need to retain the engine if you use dowels to keep the engine secure ?
Cheers
fred
 

Fred22

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Well on another forum I am also doing this thread. They were kind to us and let us use their space so to speak so I put in my build thread to give them a laugh :) Anyways the maker of this kit came on and said the instructions in the kit were in error and told me the rear edge of the wing needed to be 8 1/4 inches from the end of the tube and the wing opening needed to be 91/4inches long. With the fix I used the measurements worked out fine. It was amazing this person came onto the board and gave me vital info so quickly and offered me a new body tube. I believe that the true test of class is how you deal with difficulty and Hawks Hobby passed with flying colours. Do not let this stop you from buying this kit :)
Anyways I put together the ramjets ,right wing and rear stab components. The balsa was nice,smooth and thick just like the way I like my coffee :) heres some pictures :)

balsa pieces.jpg


ramjets.jpg


wing in sections.jpg


rear stab and wing.jpg


finished wing with extra glue on joins.jpg
 

Pantherjon

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Thanks :) The fibreglass sounds good as I have never worked with that before either :) John how big a screw do you need to retain the engine if you use dowels to keep the engine secure ?
Cheers
fred
Dowels? Just curious where you would be putting the dowels..

Anyways, most of the motor retention I have on my High Power rockets involves 2 6-32 blind nuts, 2 6-32 (1.5-2" long) screws and 2 washers..Drill 2 3/16" holes almost 1/4" away on each side of the motor tube opening. Then hammer the blind nut in and set with CA or epoxy...As you have the motor mount completely assembled, there is another way to do something similar..Instead of using blind nuts you can use threaded inserts..Drill 2 holes, thread them in, then you have threaded inserts for your screws to go in..

Pictures 1 and 2 show the motor retention used on my 3" Thor..Blind nuts, the screws and washers..I used an additional 3 nuts as I couldn't find screws with thread all the way to the head and needed a 'spacer'..1 is without motor and 2 is with a motor in the tube..
Piture 3 shows a threaded insert with a screw..You will of course want a screw a bit longer then the one in the picture because of the aft closure on the RMS or thrust ring on a single use motor..

Motor Retention 001.jpg


Motor Retention 003.jpg


Motor Retention 005.jpg
 

Handeman

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Another type of fastener I've used to add or enhance retention on a built rocket, when there is enough room, is the molly bolt like these. They won't pull out because of stripped threads or thin centering ring.

A second method I've used on minimum dia rockets was to take a large paper clip, about 1/16" dia. wire, and cut it up and make a two deep U shapes out of it. Don't worry if the legs are straight, it's actually better if they're a little wavy. I epoxy these to the outside of the BT opposite of each other.
If the rocket has four fins, you can lay them along a fin root when adding fillets. If it has three fins, put one by a fin root and the other opposite, where the lug or rail button might go. I use thin copper wire through the loops to retain the motor.
 
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Fred22

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Dowels? Just curious where you would be putting the dowels..

Anyways, most of the motor retention I have on my High Power rockets involves 2 6-32 blind nuts, 2 6-32 (1.5-2" long) screws and 2 washers..Drill 2 3/16" holes almost 1/4" away on each side of the motor tube opening. Then hammer the blind nut in and set with CA or epoxy...As you have the motor mount completely assembled, there is another way to do something similar..Instead of using blind nuts you can use threaded inserts..Drill 2 holes, thread them in, then you have threaded inserts for your screws to go in..

Pictures 1 and 2 show the motor retention used on my 3" Thor..Blind nuts, the screws and washers..I used an additional 3 nuts as I couldn't find screws with thread all the way to the head and needed a 'spacer'..1 is without motor and 2 is with a motor in the tube..
Piture 3 shows a threaded insert with a screw..You will of course want a screw a bit longer then the one in the picture because of the aft closure on the RMS or thrust ring on a single use motor..
Wow that looks great John :)
Cheers
fred
 

Fred22

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Another type of fastener I've used to add or enhance retention on a built rocket, when there is enough room, is the molly bolt like these. They won't pull out because of stripped threads or thin centering ring.

A second method I've used on minimum dia rockets was to take a large paper clip, about 1/16" dia. wire, and cut it up and make a two deep U shapes out of it. Don't worry if the legs are straight, it's actually better if they're a little wavy. I epoxy these to the outside of the BT opposite of each other.
If the rocket has four fins, you can lay them along a fin root when adding fillets. If it has three fins, put one by a fin root and the other opposite, where the lug or rail button might go. I use thin copper wire through the loops to retain the motor.
Another great set of ideas. Darn bald spot going to get bigger from all the head rubbin I do trying to figure out what would work best :) Those retaining rings are mightey pricey although no doubt great value at the price :)
Cheer
fred
 
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Fred22

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Well upwards and onwards :)
Well guys the wing span on this bird is mighty impressive :) I also enjoyed the book and now it generates good vibes as a fine weight :)

wing span.jpg


positive karma.jpg
 

Fred22

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Well the rear stab involved first putting in a centre line at about 65 millimeters:) This is for me a big rear stab :)

rear stab centre line.jpg


rear stab scale.jpg


rear stab dry.jpg
 

Fred22

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Well Loretta at Hawks Hobby pointed out I had not assembled the tail properly as the grain was lined up wrong. I used the form the tail pieces were cut out of to draw out then cut a single piece tail from light ply. I lined up the fuselage as level on a work bench with a torpedo level. I then checked the tail and did a little grinding then put on the tail stab assembly. Man this rocket is a real cooker and hard to put away. Thanks again to loretta :)
Cheers
fred

major sub 1.jpg


sub 2.jpg
 

MysticalRockets

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Guys who sells motor hooks and engine blocks for 29mm?
Thanks
Fred
Hanger 11 usually has them.

Hooks are normally what I use, but you can also use the screen clips method as well. It works quite well.
 
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