MRadu

Well I got a little side tracked. Did anyone notice my photos in some of my last posts where I have a center drop tank? Well, I want to add this tank and make it drop-able, however, I’m not sure how to mount and make it release at the moment. Thinking about dropping it made me think about it breaking and that I will have to repair it all the time.

So I have attempted to make a latex mold so I can make as many as I want.

The photos one, two and three show covering the two halves of the drop tank with Laytex. This took two days to cure fully due to the thick areas in the corners.

Photos five and six show the outer shell required to assist the latex to hold it’s shape.
Photos six, seven and eight show my new molds ready to try laying out new fiberglass and se how it comes out.

Photo nine shows my first half. I pulled it out of the mold before completely cured. That is why there is that dent in the side. I’ll have to make another one and go slower.

MRadu

Ok now back to the ARF and the canopy. These photos show after sanding and sanding I laid three strips of 1/16” black pin stripping tape. Then with three coats of bondo filler and more sanding this is what it looks like. Maybe a little more sanding and the canopy will be complete.

MRadu

Here I’m hooking up the tail wheel. For the tail hook I used the red and yellow golden rod. The yellow fits perfectly into the white outer tube guide that is already installed. This tube guide is there for the retract, however, with this scale tail wheel the retract is located in the center so I’m using this guide for the tail hook.

For the retract I’m using a 4-40 rod and the red tube as a guide. I’ll show this soon.

MRadu

These photos show how I made dummy scale exhaust pipes. I used 11/32” brass tubes. Cut three and then silver solder them together. I’ll make a mount and attach them to the firewall.

MRadu

Now that all the fiber glassing is complete everything needs to be sanded. Photos one through five show that after general sanding the resin with 80 grit paper to remove the hight spots, I use a pencil to locate areas that need bondo filler.

Photos six through twelve show different stages of sanding and primer. The primer shows all areas that require fixing. Once I spray the primer on I used 120 grit paper and them 220 grit. Then another coat of primer. Once smooth (well smooth enough) that’s when I’ll start making my panel lines.

Chad Veich

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Looking very nice MRadu. Regarding the drop tank I made some large ones for a friend's P-47 project that were droppable. We were concerned about them breaking as well so I vacuum formed them from very thin styrene and then glued the two shells around a skeleton made out of 6mm Depron foam. The tanks are very light and thus do not break when dropped. You might have a super detailed static display one from glass and then use a simplified vacuum formed version for dropping. Just a suggestion. Good luck with it either way.

MRadu

Chad,

Thank you for your reply. Not sure anyone was watching. As for the foam drop-able tanks. I did not know what to do. This is my first time with fiber glassing and molds. In fact, this is my my first time glassing a plane. That is why I'm posting.

Will you spend some time explaining how you made the light weight drop tanks? Maybe photos? Also how did you make them attach and drop form the plane?

I'm working on a design for releasing them. Just not sure if it will work. I'll post my first design tomorrow.

Thanks so much for the reply. I want to know how to make new things. There is always more than one way to do the same task!

BobH

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One method to make your foam tank, take your shape and cut some balsa disks of the correct shape at locations along the length; these will act like "bulkheads" . This will establish the bask shape in 3D. Between those "stations' add Foam fleshing in the entire form. Now you just need to sand away the foam to the balsa or light ply disks and you'll have your shape. Use light weight glass cloth to cover and finish. You can add details if you like, like the fill cap, lettering etc.

Bob Violet, bvm models, sells a "stores" release. Its air operated. Tower sells a foremost bomb release, this is servo actuated. It's simply a spring loaded pin that indexes into some kind of ring you have made on your fuel tank.

MRadu

Thanks Bob,
I'll check out the release options from BVM and Tower and get back to you. Your idea about making bulkheads is great. I'm going to try to make some bulkhead disks and insert them into my fiber glass molds.

Thanks for the advice.

rt3232

My Feedback: (6)

Hi MRadu

To keep the impact damage down fill your tanks with a product called Great stuff the blue lable an expanding foam (available at H/D and outher home building supliers) it is light, but might take a try or two to get the right amount and you might have to have 2 small holes to relive excess material might even add just the rite weight to get a clean drop and break away.

Good luck with your project

Cheers Bob T

MRadu

Thanks Bob T. and Bob H. I have ordered the stuff you mentioned and going to the hardware store to find the other and will be giving it a try.

This week I have had the flu and my mind has been on making a scale exhaust. While my head felt double it’s size I somehow drew up this muffler and then programed it into a 3-axis milling machine. This is what I came up with. The one shown here is my fourth prototype. I think I may need one more to finalize the design. However, it now fits nicely.

My next post shows what I came up with for the pipes.

I'm having trouble uploading photos. I keep getting an error "500 - Internal Server Error" Has anyone know what is occurring?

kmtranmd

My Feedback: (71)

Here's my set up for gear doors:
20mm air cylinders from Hobby King for $6/pc.
Sequencer also from Hobby King.
Works great...

MRadu

Thanks Kmtranmd for the post and photo. This is scale and I like it. Great job! I plan to use this system. However, I already purchased the U.P.3 air valve and this system perform the gear and doors.

http://rcscaleproducts.info/products...retract-valve/

I also use a system that the servo pulls and pushes the air valve and a second valve doors the doors. This second valve is mounted next to the servo arm so that it can be sequenced.

I'll post a photo if you want to see it.

Thanks again for the post. Great work!

Chad Veich

My Feedback: (60)

Sorry for the delayed reply MRadu, I missed your post somehow. Unfortunately I did not take any pics of the tank during construction, not sure why as I generally photograph everything. However, the drawing below shows the internal structure which was simply cut from 3/16" thick Depron foam. The two Depron halves were joined with a thin plywood frame between them which formed the flange that runs around the center of the tank. I made a plug and vacuum formed two shells from .030" Styrene plastic which were then assembled over the framework. The Depron is strong enough to make the tank rigid but light and flexible enough to prevent the tank from breaking when dropped. It's a bit of work but once you have the plug made you can make as many tanks as you want fairly rapidly. (And sell them to your friends!) The tank was set up to use one of the off-the-shelf drop mechanisms. In this case I think it was a Vortac which is no longer available but the others referenced in previous posts will work just as well.

Chad Veich

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Here is the tank "in action" on the Yellow P-47 built by Dave Gianakos and Bob Frey.

MRadu

Chad that is great. Your example has given me some great ideas. I'm going to try placing the bulk heads directly into the wet fiber glass while into the mold. Once the fiber glass has harden and I can pull each half out of the mold I'll let each cure and then try to use the expanding foam to fill in between the bulk heads.

What do you think? Chad? Bob T and Bob H?

MRadu

Well I still have the flu and I wanted to show you some photos of making a scale exhaust.
The one shown here is my fourth prototype. I think I may need one more to finalize the design. However, it now fits nicely.

My next post shows what I came up with for the pipes.

MRadu

Photos one and two show the base for the pipes I made. The three holes are slightly smaller than the pipes at 11/32”.

SIDE NOTE: I ordered a scale exhaust from Keleo (http://www.keleo-creations.com/) for my DA50 engine for my P-51 Mustang (from AreoWorks) and at $350.00 I thought I might try to make my own. However, from the exhaust kit from Keleo there was this type of silicon tube that can handle the temperature of the exhaust. They sell it in foot lengths and this gave the idea of making my own.

Photos 3 - 7 show the brass 11/32” pipes hammered into the aluminum base. I’ll have to mill out another as these photos show that I hammered them into the wrong end. I did it correctly on my second one shown here.

However, I then using the band saw and belt sander, I cut the ends at a angle. Then using that silicon tube I cut short pieces to attach the the pipes to the muffler. I’ll use the flange of the base to mount to hard wood blocks to the fire wall. This way the pipes will not be touching the sides of the fuselage.

My worry at the moment is this. Does anyone know or think that my new muffler might be to constricting? I mean could these three pipes create to much back pressure and hinder the performance of the engine?

If any has some ideas and or thought please let me know.

MRadu

Here I’m given the fuselage the second and third bondo filler touch up and the third and forth sanding.

Photos 5, 6 and 7 show the main reason why I decided to remove the MonoKote and cover with fiber glass. I like the design, however, I dislike the gaps in the tail!
Now I get to fill in the gaps.

rt3232

My Feedback: (6)

Hi MRadu

Frist that set up look great.
In my research on mufflers I found the that you have to have 90 percent (volum) opening in th pipes compaired to the port in the engine,
To avoid reduced performance. If you have noise restrictions at your field like we do you might want to add baffles.

Cheers Bob T

MRadu

Hello Bob T,

Thanks for the encouragement. Not to much of a noise issue at my park. Jets fly at my park and their is grater. I just found other build threads with your outstanding work! Great work! Please follow and assist any time you want. I welcome your assistance and guidance.

I'm really looking forward to even test firing the engine with my custom muffler. If it works out well, anyone else who may want one I'll be happy to make one or two. I have the milling machine all set up.

MRadu

Here is a modification where I have started to make the tail a little more scale. On the scale bird there is not such a large gap between the elevators and the fuselage. So I decided to make extension and add them to each side of the fuselage at the tail. This is scale, however, not as large as I’m making them. I’m forced to as the elevators are pre-installed. I think it looks better. It's looks will improve more with paint too. I hope. :-)

MRadu

Now it's time to tint the canopy. I like to give my canopies a slight tint as this takes away the plastic model look and give a more real look and feel.

Photos one and two show the un-tinted canopy. Also in two and three you can see the dye and how I heat it up.

I use “Ritz” color dye. That you can buy at almost any grocery store. It comes in different colors and according to Bob Violet a mixture of yellow and just a hint of red makes a tangerine that is correct. I spent a fortune on extra canopies and I simply did not like the look of it. I use black. No mixing colors and just add water and heat up.

Now too much heat and you’ll melt the canopy. Too cold and dye wont take to canopy. This just takes practice on a scrap piece before pouring over canopy. Yes pour not dip. I have tried this as well and if any part of the canopy touches the pot (anywhere including sides and edge or handles) it will melt a scratch that can not be removed. I poured an even coat three times over the top and one on the inside. Then rinsed with water and dried off. Then cut to shape.

colesifer3d314

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you are a master craftsman...I have this model in the box with the robart electric retracts i plan on doing all of this to as well. i am following all of this with praise and trying to learn as much as possible from you..thank you for posting your progress..

i will post my build when i begin and hopefully can get tips from you and other builders as i go.

Thanks,
Cole

MRadu

Thanks Colesifer,

Nice of you to say. I just keep trying and ask lots of questions. Just jump in and try new things. I'll be more than happy to share my experience. I have had many mistakes that the odds were in my favor that I'd get some things correct.
Remember to have fun. When it gets difficult take a break.

Are you going to remove the MonoKote and glass your Corsair?

I have the Robart air retracts and now wish I had paid for the Down and Locked conversion (electric) versions.

I look forward to seeing you progress.

Thanks for the kind words.