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Nov 13, 2018, 04:16 PM
Umón Takahashi
Wow man! Congratulations! I can't wait to see how you will skin the wings and fuselage. I just have one question, in the same plans do you have the fuselage formers and patterns for ribs?
And just one observation, I can see you joined the ribs and the main spar without peeling off the paper. If you do that you will save more weight, and you will have a better bond. Sometimes when you use hot glue on top of the paper it tends to go out with the stress and time, and mostly the white foamboard.
Best regards and please keep on going!!
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Nov 13, 2018, 04:49 PM
Registered User
Yeah, good question, the plans I have are shown in one of the first pictures in the article, but thanks for reminding me to share the link with you guys...
https://aerofred.com/details.php?image_id=98390
(and I used Adobe acrobat free version to scale the plans and to print them in tiles.)
... Back to your other comment, I left the paper on because I wanted the added strength for the core of the wing and fuselage and I wasn't aware as to the board becoming weak with the paper on it. But, what's done is done so I'll just leave it at that and maybe your suggestion will help me in a future project or others reading your comment. Thanks for the great input everyone, I really appreciate it! On another note I haven't had much time as of recent to work on the plane or write here so the only thing I've gotten done from my last post is finishing the other side if the fuselage with ribs. The next step is to cut and glue pieces of foam horizontally in between the ribs to add strength that way. Then I will be able to make the elevator and make the rudder a little bit thicker so that it looks natural. As always, thanks for reading and happy building.
Nov 25, 2018, 11:02 PM
Registered User

Progress over Thanksgiving weekend


So I haven't been working much on the plane before this weekend because I was In the process of getting a job at Sargento cheese in Wisconsin (part of the youth co-op). So I got the job so that's off my shoulders now and can work on the plane with the rest of my spare time.

I put the pieces in for horizontal strength, that's pretty self explanatory then I set in on making the tail section of the airplane. The rudder is three layers of foam and the elevator is just two. I did it this way because making the rudder just two thick would put one piece off-center and that would look bad sooooo all of that stuff is in the pictures. I laminated the two pieces of the rudder (I should've taken the advice that someone gave me earlier here and taken the paper off both sides of the foam to lighten it up but I forgot about that.) then I used my extra long razor to cut chamfer on the front and back of the wing to give it a little bit of aerodynamic shape. After that I sanded it to look better and be more smooth. Some of you might ask how my hinge is set up so what I did is before I laminated the two halves together I put packaging tape where my hinge will be on the insides of the two halves then I glue it all together and cut out my hinge on either side. Then I moved onto the rudder using a similar strategy so I won't go into those details. And finally I cut the slot for the elevator, squared it all away and glued it in place. It isn't very sturdy at all as of now but I'll add more support underneath the future outer skin of the plane.
As always thanks of reading and happy building.

The heck! I can't upload any pictures or even take any for RcGroups because it says "there is not enough memory" any help here?
Nov 25, 2018, 11:25 PM
low tech high tech
vtdiy's Avatar
Luke, RCGroups is having a lot of technical problems right now -- they're working on it. Don't get discouraged. Uploading photos is difficult at the moment.

Not sure what is saying "not enough memory" computer, phone, camera? If so, that's the device, not RCG. You may have too many saved files for your memory capacity.

If it's RCG and you are getting a message more like the attachment is too large, see if you can reduce the size of your photo files to 600 pixels wide.

If you are getting a message that the upload to RCG failed -- that's a symptom of the problems going on here temporarily. Just retry it a few times -- that seems to work for me at present.

If you are getting kicked off of RCG with a message that you've used up your logon attempts and used the wrong password, ignore that and try refreshing the page one or two times -- that also seems to work for me.

Sorry it's difficult at present -- but that should clear up eventually when they work out the present bugs.

Keep building!
Nov 26, 2018, 12:12 AM
Build straight - Fly twisty
Whiskers's Avatar

Picture Test


The site is working here...
Nov 26, 2018, 07:52 AM
Registered User
Thanks for your help! I just had to crop each one a little bit.
Nov 26, 2018, 08:59 AM
Registered User
Luke
That does indeed look impressive.
My only comment is that with that type of fuselage construction there is almost as much foam (and weight) inside the fuselage as there will be in the skin than surrounds them.
The bit that annoys me is that when the skin is complete all round the great majority of the foam inside the fuselage adds virtually nothing to its final strength and rigidity!
Difficult to build but a stressed skin over hollow ring fuselage formers gives the greatest strength to weight ratio.

The same also applies to the wings but the weight penalty of a conventional 'spar and rib' structure over a fully stressed skin is much less.

So your Corsair will indeed be light but not quite as light as it could be.
Nov 26, 2018, 09:02 AM
An itch?. Scratch build.
eflightray's Avatar
Too late to the party, again.

But could I suggest a possibly better way of doing the fuselage, perhaps for the next one.

Start with a box, then add part formers to the outside, (pictures below may help).

The box gives you a nice straight stiff fuselage, plus a handy place to mount the gear, motor, battery etc.

Ray.
Nov 26, 2018, 12:16 PM
Registered User
Quorneng, to answer your comment, that's a really good idea but seeing as this was my first giant scale foamie that would probably turn out to be a disaster. Maybe next time!

And, eflightray, that looks rally nice, I hope mine turns out half as good��! But I wonder how that style fuselage effects weight, even with the lightening holes it looks very sturdy but heavier. If that's your plane could I ask some more specific info about it?

Thanks for all the interest in my plane every body!
Nov 26, 2018, 02:17 PM
An itch?. Scratch build.
eflightray's Avatar
Quote:
Originally Posted by Luke Rondeau
.......................

And, eflightray, ...................... If that's your plane could I ask some more specific info about it?
Here's the thread --- Douglas SBD Dauntless (She's flown), Now the video.

I have also built a 72" span Spitfire the same method.

Unless you are building for ultra-lightweight indoor flying, don't worry too much about weight at this size, it will still be considerably lighter than a balsa build. My Spitfire is from a plan for a balsa, IC power version, it came out at half the flying weight.

It's more about low wing loading than overall weight.

Ray.
Last edited by eflightray; Nov 26, 2018 at 02:28 PM. Reason: Correction: I linked to the wrong thread, the one above includes some of the build.
Nov 26, 2018, 07:02 PM
Registered User
eflightray makes a good point about a large foamy.
They fly so relatively slowly that they can be seriously effected by wind and turbulence.
If it is flying at say 25 mph then even a 12 mph wind would be like flying a full size Corsair in a 100 mph gale!
In addition any turbulence from trees etc will likely be stronger than the controls can easily counter!
It will be for calm(ish) weather only but the reward will better realism in the air.
Nov 26, 2018, 07:23 PM
low tech high tech
vtdiy's Avatar
I don't think the paper on the dollar tree foamboard is such a bad idea on the internal structure. The fuselage outer skin will surely be peeled, and so the weight penalty is relatively minor, yet the internal bracing will be much stiffer. also since all of the raw edges will be glued to the skin, I don't think separation will be a problem on bulkheads as it would be on an external application.

A full sheet of Dollar Tree foam weighs 4 oz, and the paper is just half that. It doesn't seem like you have a full sheet of area total in those bulkheads and profile -- I doubt you will have picked up 2 ounces total by leaving the paper on the internal members.

However, if you're shooting for indoor flight -- every ounce counts. You'll probably need a big venue for something like that anyway. If you just want slow flight outdoors, I think you're fine so far.

When people start overloading a plane with monster motors, ESCs, heavy wiring and connectors,giant batteries, and then load the structure with fiberglass, tape, and other reinforcements, build heavy tails, add lots of commercial hardware (oversize wheel keepers, clevises, control horns) retracts, paint heavy (and then find the CG aft, so add even more weight to balance) then an ultralight plane becomes uhhhhh, not so ultralight.

Concentrate on minimizing the weight of the tail to keep the CG of the airframe as far forward as possible. Also minimize paint and the weight of any other covering materials.

Because most of the surface area of a plane is behind the CG, every coat of paint (or covering) over the whole plane moves the CG aft. Also, it takes several times as much weight in the nose of a plane to balance any increase in tail weight, because the nose to CG arm is much shorter than the tail to CG arm -- just like a seesaw. So if you're shooting for ultra-light weight, tail weight, and paint and covering weight are critical.

Reducing the size of a battery, engine and ESC to save weight will not help if doing so just means adding back equivalent ballast weight in the nose to balance a tailheavy airframe. Weight savings starts with personally analyzing the distribution of weights in your intended build structure and doing everything you can to keep the CG as far forward as possible, and after that, you can count on a light motor and gear to complete the balance.

One other point -- it's easier to build a light inline engine type scale aircraft than a radial engined type. The longer nose of an inline airframe gives a longer moment arm to the CG. It's also easier to keep gear forward -- there's more room up there. Radial engines tend to concentrate weight -- which is why they were put closer to the wing to balance full size planes. Therefore it's easier to balance an ultralight SE5A model than an ultralight Spad. Same for WW2 planes.
Last edited by vtdiy; Nov 28, 2018 at 11:57 AM.
Dec 05, 2018, 11:05 PM
Registered User
Hmmmm, good ideas, vtdiy, thanks for the input! I did a very "sketchy" cg test with just my battery and motor resting on the first horizontal rib and the cg was noticeably aft. So I'm hoping when all of the electronics are on there it will be resolved but I'm not sure what I could change without compromising the structural integrity and not being a complete overhaul. I did accomplish a little work between posts, I did a sort of test on covering my frame and, I have to say, I think it looks pretty good. So what I did was beef up my horizontal stabilizer a bit more so that it isn't so wiggly. Then I peeld the paper off some large foam scraps and bent it around the fuse on the underside of the stabilizer. On the top side I used some longer scraps and cut angles along the lengths and glued them to the vertical and horizontal stabilizer and then bent the tops of them together. This last development took me 2 hours and my previous post was around 5.
As always thanks for reading and happy building!


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