Author Topic: Drop Tanks (Read 7906 times)

Jeff Traxler · « **on:** September 10, 2016, 10:50:31 AM »

I want to include dropable tanks on my winter profile scale project.Hobby King has a plug-n-play mechanism but it is for larger 1/4 scale projects.Does anyone know of plans or have ideas to share for a working tank/bomb drop pylon.I have few ideas and I want to see if I'm on the right track.With 2.4 it should be a LOT easier than a 4th or 5th line.

chuck snyder · « **Reply #1 on:** September 10, 2016, 04:44:16 PM »

Jeff, I have bomb drops on my Typhoon, dH Hornet, and HS-129. I use a servo operated mechanism that is a copy of the old Vortac bomb drop mechanism. They work very well. I bought mine from Yellow Aircraft, but they are out of business now. They had two sizes. Maybe mr. google can help out. These units have an "FK" brand name molded in.
Chuck

Fred Cronenwett · « **Reply #2 on:** September 10, 2016, 05:26:05 PM »

Drop tanks or bombs attached to the wings are a great option

If you can't find the vortac units you can make your own items just need a pin that gets pulled inside the wing to release the bomb or tank. Use a micro servo since they don't need a lot of torque to drop the tank. Put one servo at each location and just stretch wire to the servo, easier than hooking up lots of pushrods and bellcranks.

1) Build one set that is perfect and is used for Static judging only
2) the flying set are same size, color and shape and will get beat up when then land

Just don't hit the judges.... the toggle switch on the 2.4 Ghz system can drop the units

Great stuff....

Fred

Jeff Traxler · « **Reply #3 on:** September 10, 2016, 10:42:32 PM »

Chuck,
Thanx for the photo and the info.I'll do some searching and see what I can find.I will need 4 so I hope I can locate some already made.What I had in mind is similar to the photo so I'll just make some if need be.

Fred,
I am just starting to draw up the wing plans and a servo at every pylon vs. pushrods was something I wanted to bring up in this thread.Servos it is.Can I just plug all 4 into a splitter and use 1 channel?I can make 4 extra tanks for dropping easy enough.I'm going to make a plug and a mold and then make the tanks with fiberglass.One of the 3 views I have shows 500 lb. bombs mounted on the pylons as well.It would be kinda neat to drop 2 tanks as 1 task and 2 bombs as another,both at different altitudes and attitudes.

Fred Cronenwett · « **Reply #4 on:** September 11, 2016, 06:55:54 AM »

Yes one channel can operate one or more servos you just need a Y harness (hooks to two servos) or you make a quad harness. Basically each servo sees the same signal, power and ground from that one channel.

at the 5:45 minute mark I talk about the Y harness in this video

at the 7:39 minute mark talk about the quad harness

Fred

chuck snyder · « **Reply #5 on:** September 11, 2016, 06:56:25 AM »

Jeff, Each of my models has a bomb on each wing. They are controlled by one servo and flex cable pushrods. Four servos can be operated from one channel with "wye" harnesses. I can see your system accomplished with one servo and one channel. Controlled with a three position switch with center being bombs latched. Move the switch one way and the tanks drop; move it the other and the bombs drop.

My bombs are also fiberglass and made in my own molds. I use 2 ounce cloth for the bodies and several extra layers at the front. This helps prevent breakage and allows them to fly true without tumbling. Although you want the tanks to tumble. I join the shells in the mold using two-part expandable polyurethane foam. You have to build the mold so the two halves can be put together precisely. The foam glues them together in perfect alignment. For bombs that have a circular or square surround on the fins I make a long foam mandrel and layup glass cloth. After it cures I slice off the proper length. The mandrel gets destroyed, but is easy to remove from the fin component.

Chuck

Paul Smith · « **Reply #6 on:** September 11, 2016, 05:02:17 PM »

If you are able to get 20 points out of two different "drop options" you will be exploring a new way to exploit the rules.

Maybe I can do the loop or the overshoot twice and get away with that, too.

Jeff Traxler · « **Reply #7 on:** September 12, 2016, 08:07:19 AM »

Quote from: Paul Smith on September 11, 2016, 05:02:17 PM

If you are able to get 20 points out of two different "drop options" you will be exploring a new way to exploit the rules.

Maybe I can do the loop or the overshoot twice and get away with that, too.

The rule book say I can pick up to 6 different flight options.Bomb drop and drop tanks have different numbers in the rule book so I can only assume they are different manuvers.Both have different objectives and sets of errors and NEITHER is an automatic 10 points like the multi option and that only counts if the engines stay running the whole flight.If 20 points are awarded it is because of the flying skills and the realism of the option performed.The reason for this thread is the difficult part......getting the tanks/bombs to release from the airplane in a REALISTIC manner,not for EASY points and exploiting the rules.I am however making an electric twin to get those EASY points

Exploiting rules is the American way!This project is still in the drawing/daydream stage so for future referance......try not to get your panties all bunched up until I actually cheat!!

Fred Cronenwett · « **Reply #8 on:** September 12, 2016, 10:57:50 AM »

agreed...if you pick your features on the model and the aircraft you can either have a hard time getting options or have more than you can use. consider these two planes. Multi-engine is an easy 10 points if all of the motors are working.

Piper Cub - Throttle only - It's hard to get 6 options together for his model

   throttle control
   45 degree
   touch
   go
   missed approach
   Taxi

P-51 with retracts, air scoop door, flaps and drop tanks - you can get up to 11 options to pick from, but only can use 6 of them

   throttle control
   45 degree
   touch
   go
   missed approach
   Taxi
   flaps
   retract gear
   extend gear
   open close scoop door
   drop tanks

Jeff Traxler · « **Reply #9 on:** September 13, 2016, 09:00:15 PM »

The model I want to make will be profile.1" max fuse thickness.The tanks are round in the front view with a diameter of about 1 5/8".Should I make them 1" wide as well?

Paul Smith · « **Reply #10 on:** September 14, 2016, 06:57:32 AM »

Quote from: Fred Cronenwett on September 12, 2016, 10:57:50 AM

agreed...if you pick your features on the model and the aircraft you can either have a hard time getting options or have more than you can use. consider these two planes. Multi-engine is an easy 10 points if all of the motors are working.

Piper Cub - Throttle only - It's hard to get 6 options together for his model

   throttle control
   45 degree
   touch
   go
   missed approach
   Taxi

P-51 with retracts, air scoop door, flaps and drop tanks - you can get up to 11 options to pick from, but only can use 6 of them

   throttle control
   45 degree
   touch
   go
   missed approach
   Taxi
   flaps
   retract gear
   extend gear
   open close scoop door
   drop tanks

Piper Cubs can do loops and other aerobatics. In fact they SHOULD, or else be downgraded under realism.

Avaiojet · « **Reply #11 on:** September 14, 2016, 09:41:56 AM »

Quote from: Fred Cronenwett on September 12, 2016, 10:57:50 AM

agreed...if you pick your features on the model and the aircraft you can either have a hard time getting options or have more than you can use. consider these two planes. Multi-engine is an easy 10 points if all of the motors are working.

Piper Cub - Throttle only - It's hard to get 6 options together for his model

   throttle control
   45 degree
   touch
   go
   missed approach
   Taxi

P-51 with retracts, air scoop door, flaps and drop tanks - you can get up to 11 options to pick from, but only can use 6 of them

   throttle control
   45 degree
   touch
   go
   missed approach
   Taxi
   flaps
   retract gear
   extend gear
   open close scoop door
   drop tanks

Fred,

Nice examples. I always said there's more to scale contects than just building a model and showing up.

I'm guessing my Gee Bee Z wouldn't be a good contender?

Looks like a twin would be more worth the effort.

Charles

Paul Smith · « **Reply #12 on:** September 14, 2016, 10:05:22 AM »

Correctomundo. The GeeBees barely flew as full size planes and don't do well as models. While thought to be "cool" and challenging, the GeeBee is a bad choice for many reasons.

However, it DOES avoid the rarely-imposed retract gear penalty.

Mark Scarborough · « **Reply #13 on:** September 14, 2016, 10:40:15 AM »

while what Paul says is true to an extent, the Gee Bees actually flew within reason as full scale, and I have seen many replica models that flew very well, it is true that the flight options are limited.
HOWEVER, being that I judge Scale events, I disagree on many fronts. A well built and documented model that flies reasonably well and performs the options available well will win. John Brodak has many wins with a Shoestring F1 model, Locally there have been numerous winners that have limited options, most recently the Regionals were won with a small Mr Mulligan model that flew ok, but static judged well.. so it aint always so cut and dried....

that said, the more mechanical options for flight you can use, as in retracts, bomb drops, multi engine, and such, the more scoring potential you have........

Paul Smith · « **Reply #14 on:** September 14, 2016, 01:32:51 PM »

I can't really agree with most of that.

Mr. Brodak's Shoestring, 1/4 scale model of a very small airplane, is a classic example of sidestepping the challenge of scale by choosing a model with a minimal scale factor.

Out of the six options, the Shoestring or any similar model can still get the whole 100 points. Models with numerous 2.4 gizmos still have the same maximum of 100.

The 2.4 gizmos effectively mask the fact that an overweight model doesn't fly very well. The Rule Book needs to be modernized to eliminate cheap points awarded for now-simple options that were a genuine challenge in the past.

Avaiojet · « **Reply #15 on:** September 14, 2016, 02:08:19 PM »

I do have this Grumman Widgeon I purchased a few years ago.

It's an ARF designed for electric, but I purchased it to strip it down totally and bolt on a couple of IC's.

With engine nacelle changes, (to the older radial engines that is as seen in this photo,) plus retracts, possibly flaps and definitely throttle, it could be a contender? It would have be 2.4. I'm still working on a handle to eliminate the bulky TX on your hip.

I haven't addressed this Widgeon or my F3F-1 because of the retracts. They would have to be scratch built, resemble the actual aircraft's gear and be rock solid in operation. Not an easy task for this kind of gear.

Getting points before you even fly the thing is something to take advantage of.

Another one of my dreams.

Jeff, sorry about the off topic.

Charles

Tim Wescott · « **Reply #16 on:** September 14, 2016, 02:13:46 PM »

If you don't feel up to making your own "Y" harness, MaxxProd shows them here.

Will Hinton · « **Reply #17 on:** September 14, 2016, 03:20:12 PM »

Mr. Smith says the rules should be modernized etc. which proves he must not be keeping up with the event. Myself and several other judges gathered together both via email and then a final (almost) meeting at the Toledo show fairly recently and did just that. Some notable top competitors were present and made themselvs known as well even though they weren't official members of the committee. Many hours were put in during this effort to upgrade the event.
Many scale fliers from all over have commented on the improvement of the rules as now written.

Fred Cronenwett · « **Reply #18 on:** September 14, 2016, 03:36:30 PM »

Keep in mind that retracts might look easy at the flying site in terms of going up and down but the majority of the work is done in the shop making them work correctly so that when you hit the toggle switch at the flying site then go up or down without any problems. Bomb drop is the same thing, a lot of setup to make sure it works as planned at the contest so it looks simple but it there is a lot of effort behind the scenes to get that effect during the contest flight.

Some options are more flying skill, some are more mechanical but they are all worth 10 points. 100% of the flying points are earned during the flight. The vast majority of the mechanical options are earned in the shop to ensure that they work at the flying site without any problems.

Fred

Mark Scarborough · « **Reply #19 on:** September 14, 2016, 04:18:46 PM »

Quote from: Paul Smith on September 14, 2016, 01:32:51 PM

I can't really agree with most of that.

Mr. Brodak's Shoestring, 1/4 scale model of a very small airplane, is a classic example of sidestepping the challenge of scale by choosing a model with a minimal scale factor.

Out of the six options, the Shoestring or any similar model can still get the whole 100 points. Models with numerous 2.4 gizmos still have the same maximum of 100.

The 2.4 gizmos effectively mask the fact that an overweight model doesn't fly very well. The Rule Book needs to be modernized to eliminate cheap points awarded for now-simple options that were a genuine challenge in the past.

the rules are the rules, if YOU dont like or dont agree with them, then propose changes.
its like stunt,, the event is what it is, fly it or turn your back, do not spread dispariging things with no basis,,

Mr Brodak did not sidestep anything, he built a model and optimized it to score which is the objective....it sounds like in your opinion that unless you build a 4e engined bomber, and dear lord you MUST use glow power because electric sidesteps the challange,, then you are not "abiding by the challenge" ?
that makes no dang sense at all

Tim Wescott · « **Reply #20 on:** September 14, 2016, 04:21:22 PM »

Quote from: Mark Scarborough on September 14, 2016, 04:18:46 PM

Mr Brodak did not sidestep anything, he built a model and optimized it to score which is the objective.

And personally, I think it's cool that you can build a model of a basic airplane, with no bells and no whistles, then go out and win. Multi-engine whiz-bang models with drop tanks and bombs and flaps and all that are nice, but I'd prefer to build a basic Piper Cub or Cessna and do my best with it.

Paul Smith · « **Reply #21 on:** September 14, 2016, 08:00:30 PM »

Quote from: Will Hinton on September 14, 2016, 03:20:12 PM

Mr. Smith says the rules should be modernized etc. which proves he must not be keeping up with the event. Myself and several other judges gathered together both via email and then a final (almost) meeting at the Toledo show fairly recently and did just that. Some notable top competitors were present and made themselvs known as well even though they weren't official members of the committee. Many hours were put in during this effort to upgrade the event.
Many scale fliers from all over have commented on the improvement of the rules as now written.

This is the first I've heard of a meeting in Toledo. I guess with all the dozens of people in CL Scale you can't invite everybody. Coincidentally, I attend The Toledo RC Show every year and could have dropped in if invited.

So I guess Will is saying that was the one-and-only chance to comment on the rules? So now ALL discussion is now closed?

Tim Wescott · « **Reply #22 on:** September 14, 2016, 08:20:38 PM »

Quote from: Paul Smith on September 14, 2016, 08:00:30 PM

This is the first I've heard of a meeting in Toledo. I guess with all the dozens of people in CL Scale you can't invite everybody. Coincidentally, I attend The Toledo RC Show every year and could have dropped in if invited.

So I guess Will is saying that was the one-and-only chance to comment on the rules? So now ALL discussion is now closed?

If you had read the rules, you'd have known that there's rules for changing the rules. And you'd know that all you need to do to submit a proposal is to fill out a form and send it in.

http://www.modelaircraft.org/events/ruleproposals.aspx

Now that you know how, there's no reason to stand back and complain, unless you just want to irritate the people around you.

Will Hinton · « **Reply #23 on:** September 15, 2016, 06:43:39 AM »

The committee put out the notice of its existance as soon as the decision was made to form it. We did everything we could to make it known to the general scale public, the Toledo Show announced the meeting over the PA system, we put the new rules proposals out via the AMA as required, and if you would have been watching, you had every chance for input that everyone else had, which was plenty.
The meeting at "the show" was only a culmination of months of emails, phone calls, and the like. This was all done through AMA, by the way, and according to the proper procedures. Ask around, Paul, check it out with others.

Jeff Traxler · « **Reply #24 on:** September 15, 2016, 07:53:37 AM »

I'm still trying to figure out how designing a release,making the linkage work for multiple tanks,bombs or a combination,making a plug and then a mold to make static and flying dropable stores and then make them function in a realistic manner every flight is taking the "EASY" way out.I have a Waco Model ARE with flaps for Fun Scale.I have never flown a throttled C/L model and thought that would be a good place to start.My profile scale model discussed here will have 2 motors and droppable stores to add to the complexity,certainly not for the ease of the project.The other thing I need for this project besides the drop tanks is one of the start up sequencers Fred has on the B-29 only for a twin.........Mr.Wescott

#^I have an idea for the puff of oil smoke that happens when you start a radial,maybe it could be hooked up to the sequencer.

Fred Cronenwett · « **Reply #25 on:** September 16, 2016, 11:05:33 AM »

The TUT timer for the engine start sequence can also work on a twin, Tim can give you the details on how that is plugged in. I have noticed that the speed controls need to have the same timing or settings to work correctly with the TUT Timer. I had to sync the ESC with the receiver one at a time so that they were all set the same, then hook up to the TUT timer

Flaps are a great option, one servo and you are done, then you just have learn how to fly the model correctly. You can also put a servo speed reducer to the flaps. This way when you drop the flaps with a toggle the they do not snap down into position (changes the trim of the model). Dave R/C Electronics sells these units, very easy to use. It plugs between the receiver and the servo.

Fred

Tim Wescott · « **Reply #26 on:** September 16, 2016, 11:20:31 AM »

Quote from: Fred Cronenwett on September 16, 2016, 11:05:33 AM

The TUT timer for the engine start sequence can also work on a twin, Tim can give you the details on how that is plugged in. I have noticed that the speed controls need to have the same timing or settings to work correctly with the TUT Timer. I had to sync the ESC with the receiver one at a time so that they were all set the same, then hook up to the TUT timer

Flaps are a great option, one servo and you are done, then you just have learn how to fly the model correctly. You can also put a servo speed reducer to the flaps. This way when you drop the flaps with a toggle the they do not snap down into position (changes the trim of the model). Dave R/C Electronics sells these units, very easy to use. It plugs between the receiver and the servo.

Fred

Just hook up engines 1 & 2 like the drawing, and leave off 3 & 4.

I think that if your computer transmitter is fancy enough you can do the flap speed reduction in the transmitter.

One thing that I would want to do, if I had LG on a plane, is to try to get my hands on some movies of the retract action -- each plane seems to sequence the retracts differently, and the ones that retract hydraulically often only have one or the other wheel going up at a time because of the way the plumbing is done.

(One of the planes I'd like to model is a Cessna CR-3, which had hand-cranked retracts. Not only would you want those to retract slowly, but you'd want to mix in some wobble into the elevator and aileron controls, to simulate the pilot moving around as he's cranking the gear. Again -- you need movies to get it right).

Jeff Traxler · « **Reply #27 on:** September 16, 2016, 02:10:34 PM »

I have had the 3 view with the tanks blown up to size and plan to spend the evening carving the tank and pylon plugs.I'll start on the molds tomorrow.Might as well make sure they work before I build them in the wing.

As far as the flaps for the Waco I was looking at a transmitter that had a pot so I could dial in as much as needed and as fast.I want to be able to use different angles thru out the flight instead of full deflection or none.Weather,runway surface,length determine how much flap on T/O and landing are needed.I never used full flaps on landing unless I was coming in over an obsticle and/or wanted to land short.It will take some practice but I love flying so we'll get her figured out.I will look online for the pilots manual and at the cockpit photos I have to see if I can figure out if they were mechanical or electric flaps.That should help me with scale deployment.

Jeff Traxler · « **Reply #28 on:** September 18, 2016, 10:15:33 AM »

I want to use these tanks on a profile scale XP-61-E.An experimental bubble canopy version of the Black Widow that was going to be developed as a long range fighter bomber right at the end of the war.Two were completed,the radar in the nose was removed and they were fitted with 4 machine guns similar to the nose of a P-38.One crashed after a couple flights.After a couple months the second E model had the guns removed and cameras fitted.It was redesignated the F-15 and was used sparingly after the war for recon.I have plenty of photos of the E both on the ground and in flight but none with drop tanks.The pylons can clearly be seen but not with tanks or bombs installed.If I can't document them on this particular model even tho pylons are there should I just forget this option?I have plenty of photos of earlier models with the tanks installed.

Jeff Traxler · « **Reply #29 on:** September 19, 2016, 06:35:06 AM »

I think I found enough to use them.A caption beside a photo talks of the drop tanks and the 4,000 mile range it gave the XP-61.Back to carving plugs.......

Will Hinton · « **Reply #30 on:** September 20, 2016, 07:20:56 AM »

That is a good thought, Jeff. I would love to hear from others what they think about that as a legitimate documentaion for the tanks on that particular ship. No picture, but a statement. Hmmm, interesting concept for static judging. How 'bout it guys and gals?

Jim Fruit · « **Reply #31 on:** September 20, 2016, 07:40:21 AM »

Quote from: Will Hinton on September 20, 2016, 07:20:56 AM

That is a good thought, Jeff. I would love to hear from others what they think about that as a legitimate documentaion for the tanks on that particular ship. No picture, but a statement. Hmmm, interesting concept for static judging. How 'bout it guys and gals?

Sorry, but it does not comply with the requirement for three-views or photographs. This would not preclude a dropping of stores during the flight portion of the event, but it would not comply with the static rules.

Jim fruit

Will Hinton · « **Reply #32 on:** September 20, 2016, 09:35:03 AM »

And, at least in my mind, if it doesn't comply with the rules for static, then I don't think it would be okay for a flight option.
I don't think it's an "either, or" thing, but yes or no for both portions of the judging. I lean your way on it, Jim, which is why I asked the question.

Jeff Traxler · « **Reply #33 on:** September 20, 2016, 09:47:47 AM »

Quote from: Jim Fruit on September 20, 2016, 07:40:21 AM

Sorry, but it does not comply with the requirement for three-views or photographs. This would not preclude a dropping of stores during the flight portion of the event, but it would not comply with the static rules.

Jim fruit

Hi Jim,I have 3 views with and without the tanks.There are no 3 views available for the E model.They pulled 2 B models off the line and drilled the top off the greenhouse just above the wing and put the canopy on.I have pictures to document that with a very nice profile shot of the E.Just none with tanks.Trax

Mark Scarborough · « **Reply #34 on:** September 20, 2016, 09:48:34 AM »

I dont see where you all are coming from, you are allowed to provide more than one source ( three view) for outline and accuracy and written sources are allowed to document as long as you have graphic proof of the individual aircraft veryfying color and markings..

fromthe rules
7.1.1.1 last paragraph in the section

The contestant may provide two or three types of documentation to assure that all categories of Scale Accuracy to be evaluated, and appropriate points awarded. In the event that the photographs and or the drawings and or plastic model differ, the photographs will generally take precedence. The use of three-view drawings, photographs or plastic model for proof of Accuracy of Outline will only count as one (1) page of the Sport Scale documentation.

as to the static documentation with regards to flight options,, how many scale documentation packages show that the subject is capable of a loop, or touch and go or any other flight option excepting perhaps pictures showing gear retraction.

as a Sclae judge, if I have anything stating the subject aircraft carried drop tanks and what TYPE of drop tanks, and then a picture of the other in the family of airframes showing the drop tanks in place, I do not see how you could disallow it,, I find no verbiage in the rules to support your position,,

as a scale judge and a scale board member I disagree, I find his premise and approach acceptable if he can verify what he has stated..

of course I wont be the one actually judging him so best he clarify with the actual contest admin as to their interpretation,,
but show me where its specifically disallowed.

Will Hinton · « **Reply #35 on:** September 20, 2016, 10:24:40 AM »

Thank you, Mark, I haven't had the time to do any research at this time because of life getting in the way, so you have helped a lot. Once we get Jeff out to my place in a few days or weeks and I am allowed to slow down we can get into the rules and search it out for ourselves, but you have steered us in the right direction.
I, of course, won't be able to judge his airplane because of my personal involvement in the research and documentation, but that's okay, I'll just launch for him instead.

Thanks again.

Mark Scarborough · « **Reply #36 on:** September 20, 2016, 10:35:54 AM »

Glad I could help; in some way,,
I love Scale,
and I LOVE the P-61 ( though the version Jeff is doing misses it for me, I love the turret)
I designed a Semi Scale stunter for a friend locally
I want to do one myself,,
some day, when I can fly decent, and trim decent, its right after my biplane stunt bird

keep us posted, and the rest of you if you disagree with my stance please educate me as to why
thanks

Jeff Traxler · « **Reply #37 on:** September 20, 2016, 02:46:00 PM »

Mark,
Thanx for chiming in.I think I will be within the rules.Just checking to make sure I was interpeting them correctly BEFORE to much construction was started.The pic with the caption is one I was going to use to show the Red panel lines,I'll just leave the caption on instead of trimming it off.I made the little Widow with the greenhouse but wanted something just a bit different for profile.I look forward to the comments about my strange looking P-38................

Will Hinton · « **Reply #38 on:** October 11, 2016, 08:58:16 PM »

Well, Jeff had his "Pet spider" out to my place last week and he has a winner in the making.
Jeff has this bent to making his planes look as good as the guitars he builds, and with his interest in scale, I think he's going to be a force to reckon with.

I static scored it at the top and if he gets the flying part down with it, look out.