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Bomb drops and drop tanks

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Old 07-27-2002, 02:36 PM
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Shihtzutan
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Default Bomb drops and drop tanks

Im real good at kit bashing, but making reliable release mechanisms for my 1/8 scale Top Flight P-47s wing pylons if proving to be a real headache. Top Flight no longer make the tanks or release mechanisms for the wing pylons. The tanks or bombs must be reliable to avoid dropping only one, which I fear will produce some nasty, perhaps uncontrollable yaw. Ive got a set of wing tanks for my Mustang that Id like to share with my Jug, but I think Im going to have to dedicate the drop tanks to the Mustang and scratch build the bombs and tanks for the Jug.

The problem is the wing pylon on a Thunderbolt is a narrow and over an inch and-a-half from the skin of the wing! This is probably why Top Flight gave up on the wing tanks, either that of builders had real crappy luck with them. Alas, I am addicted to realism, suggestions anyone?
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Old 07-27-2002, 04:04 PM
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Default Bomb drops and drop tanks

A little complcated... But I could draw up a bellcrank actuated, spring loaded release mechanism, to be acuated by pulling against spring tension with a fishing line or similar. I can already see it in my head.

The pylons are ABS hollow plastic shells? (I hope) Useable width and height if sticking in a rectangular piece of wood the full height? (the working area for the mechanizm) Exact height of the pylon? And exact distance from pin that retains the bomb/tank to lower wing skin?

I'll design it with 1/4 inch of the belcrank system penetrating into the wing. And then e-mail a scanned picture of the drawing.
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Old 07-27-2002, 04:48 PM
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Default Bomb drops and drop tanks

Thanks for the prompt reply,

Wing pylons are vacum formed typical stuff found in nearly all Top Flight kits, height is 1-9/16 overall from center. At present I've got a piece of 1/6 ply mounted in the pylon near where the bomb or tank would mount. The width in the inside 1" in the center but both ends are tapered like a teardrop.

Bellcranks seem to be a good idea, my vision is a built up, side mounted bellcrank, or simple arm with a pivot point. The plastic pylon would only be a sleeve. However, with only one trip/trigger, how are you getting around the bomb dangling from a single point?

I'm sort of thinking that a plastic tube mounted the long way on top of the bomb or drop tank. This fitting into a groove in the lite-ply; a simple cable inside the pylon holes the ordnance in place. The longitudinal mounting holds the ordinance straight. I think the trick is to get the cable flexible enough to be guided into the pylon, make the corner, then travel straight enough to be guided into tube and out the other side where it is held by another piece of tube. What do you think?
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Old 08-03-2002, 02:52 PM
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Dave Barrow-RCU
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Default Bomb drops and drop tanks

Try Yellow Aircraft, they have an assortment of bombs and sell release mechanism's. www.yellowaircraft.com
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Old 08-05-2002, 07:47 AM
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Default Bomb drops, the continuing saga

Thanks for the help gentleman. I'll follow those leads and let you know how I made out. I fear Yellow Aircraft is works in too large a scale to be useful, but I'll see what they have.

Do any of you know where I can purchase 1/7 or 1/8 scale 500lb bombs or 75 gal. drop tanks? I thought I saw an ad in Model Airplane News a long time ago for that kind of stuff, but alas, many vendors and distributors are no longer in business. Can anyone shoot me a web address? I really don't feel like carving what might become forever lost, if you know what I mean!

For the record, my idea didn't work. Working 1-1/2" from the underside of the wing is proving to be quite challenging. I'm halfway through a case of beer and I still haven't progressed any further (most 1/7 scale models take me about six beers to frame up and another six beers to finish). This one is looking like an easy two cases! When it's complete, you'll get to see it in Pilot Projects in upcoming Model Airplane News. Thanks for the help all .
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Old 08-05-2002, 11:21 AM
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Default Bomb drops and drop tanks

Sprin loaded belcrank, pivot point just above center of pylon's height. The lower end of the bellcrank connects to a soldered up dual "Z" pin release catch (2 "eyes" on the bomb) fish line type pull to drop. There will be a small slotted block that is the length of the space between the eyes on the bomb. (slot to let the rear pin move forward.

I'll sketch up the thing in the "paint" program in Windows... but, the above should give enogh of how to do it if you are creative.
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Old 08-05-2002, 11:50 AM
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Default Bomb drops and drop tanks

I really appreciate you not giving up on me! Yeah I'm creative, you wouldn't believe the variations I've come up with on this theme. Actually, you wouldnt believe the mess Im making on my bench! The bell cranks are a bit cumbersome if we start spring loading them but I'm willing to give it a try!

So far, Ive looked up Yellow Aircrafts bomb release mechanism and to my dismay; I was unable to find a picture of it. Their stuff is usually on the pricey side and having a length of over 3 inches for their small bomb release mechanism (A2401) leads me to believe that the damn thing will be too big, and theres a good chance it will be too wide.
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Old 09-06-2002, 05:58 AM
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Default Bomb drops and drop tanks

Starlancer's suggestion seems to be the best one so far. I got a hold of two foremost bomb release mechanisms and mounted them on the pylons using 1/16 ply. I used an antenna tube to guide a piece of fish line through the ribs to a center-mounted mini servo. The antenna tube ends just over the pylon and is fed through a piece of small brass tubing bent mounted and braced through the plywood to permit a straight pull on the bomb release eyelet. I resolved the dangling bomb problem, a phenomenon caused by holding the bomb from the pylon from a single point by holding it against a cradle build of bamboo kabob skewers. The result is a pretty scale looking pylon! Im not finished yet but I think itll work out just fine. Now I have to find myself a couple of scale 1/8 scale 500-pounders. I flirted with fabricating one and I'm convinced it's going to be a pain in the neck, it's more complex than youd think! Ill check your site, thanks for the intel.

For the record, Top Flite was no help, my e-mail didn't even get answered.
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Old 09-08-2002, 03:14 PM
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Shihtzutan E-mail Wingmfg at wingmfg@galesburg.net I think they can fix you up with some 500 gallon wing tanks for you jug plus they also have the drop tank mek for them too just try it you'll like it?
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Old 09-09-2002, 06:28 AM
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Default Bomb drops and drop tanks

Thanks for the info. I'll give them a try!
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Old 09-13-2002, 01:16 AM
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Default Bomb drops and drop tanks

Another one for multi bomb racks is a centre mounted servo, a lenght 1/16 or so wire leading out and supported to the wing tips, where you want your bombs you solder a leg of at an angle like this if you can follow drawing ----------------- your bomb has a loop on \---0---

and for multi racks have legs with longer and longer legs. as the servo moves each pair of bombs drop to get inside the pylon have long loops. I hope you can follow OZI.
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Old 09-13-2002, 05:08 AM
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Default Bomb drops and drop tanks

Originally posted by rusgmil
Get the release mechanisms from Yellow. They are identical to the old Vortec releases but come in two sizes. Wing was selling the bomb and tank (plastic) kits. FTE sells them but they are way over priced. Some manufacter need to get on the band wagon here. The release mechanisms are spring loaded to the closed position making them easy to set up. I use one leg of a bell crank to "trip" them in a wing installation or a small wire in inner nyrod for center line installations. Its really a no brainer set up (thats why I can do it). Once you have the mechanisms in your hands, you'll see what I mean. Also, you can drop one wing tank at a time. Doesn't affect the flying at all. Just don't fly around at full bore with the tanks on. It will weaken the holders and they can fail. Thats why they need to be light weight plastic.
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Old 09-13-2002, 05:11 AM
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What is FTE?
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Old 09-13-2002, 07:16 AM
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Default Bomb drops and drop tanks

Thanks, I just visited his site. Good stuff, but for this project too large. The Top FLight P-47 I'm building is 1/8 scale. I'll keep this in mind for my next project.
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Old 09-13-2002, 09:33 AM
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Default bombs and release

Another source is Hobby Lobby. Just go to their index page, then scroll down to Bomb Drop.
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Old 09-13-2002, 10:33 AM
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Thanks, I tried those, low quality and not very scale. They'd be good for 40 size planes, particularily RAF ones. Fins on American bombs are squared off, not round.
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