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Scratch Build - 1/8 Scale, C-2A Greyhound

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Scratch Build - 1/8 Scale, C-2A Greyhound

Old 12-21-2011, 10:18 PM
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chymas
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Default Scratch Build - 1/8 Scale, C-2A Greyhound



This build was inspired while I worked on this plane back in the early 90's while serving in the Navy. Needless to say I ended up seeing this plane inside and out over a period of 4 years. Ididn't have an appreciation for the plane at first but as time went onIbegan to fall in love with it. I had thought of making a model of it back then but ended up getting out of the hobby. Since returning to the hobby about a year and a half ago and finding that kits are almost a thing of the past I am now ready to take on this project.

I contacted Northrop Grumman and explained what I had in mind andasked if they could help me with three view drawings. The gentlemen there were very helpfull - Thank You!

Some of the things I have in mind are:

Engines - Syssa 30cc gas, rear exhaust is the primary reason for choosing this engine. Custom built exhaust/muffler inside engine naccels.
Custom built landing gear to replicate scale. Air actuated. - I plan to machine this myself.
Scale like slotted flaps with aileron droop.
Working cargo door.
True to scale vertical stab, rudders, and tabs - if you are unfamiliar, more to come on this later.
True to scale lighting.

I have drawn this out in CAD, it has taken me nearly 8 months to get to the point I am now. I still have some details to work out but some of that will have to be sorted out as the 3D model grows. Istarted with the naccel building a plug that I will in turn use to build molds and then the fiberglass shells. Iam doing a build up fuselage 1/4 cabnet grade plywood center "spar" 1/8" formers with 1/4" and 1/8" stringers then covered with 1/8 balsa and 1/2 oz fiberglass. As of tonight I am cutting the fuselage formers using a band saw and a jig saw. I've seen several discussions on how to transfer prints to wood - what I have found that works best for me is printing them out, rough cut the paper leaving about 1/8" or more extra, use 3m adhesive spray the back side then glue dirrectly to the wood. This leaves me with a nice crisp line for cutting - ya, no kit cutters/laser cutters being used here. This is a true scratch build from paper to paint.

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Old 12-21-2011, 10:52 PM
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Clarence
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

I did not know you were using the syssa engines. They k
Look so nice. Would like to see one running up. Maybe I should use one on my yak instead of the dle30???
Old 12-23-2011, 01:37 PM
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

I like to see how you will build this model, i'm having hard time with 3 fins and 5 rudders on my Connie, here you got 4 fins and how many rudders........

It sure is different subject and i like it, you will have to watch ur weight in the tails, it wont take much to have tail heavy airplane specially with not too long fuse in front of the wing....

Good thinking for adding functional tabs on the tailplane, those will help in reducing weight by use of mid to high range servos instead of using all MG servos. I did same on my Connie, this way i'll use high torque but non metal gear servos on the rudders but will use single MG servo for both elevators.
Old 12-23-2011, 02:03 PM
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Chad Veich
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

Neat and challenging project chymas, looking forward to your build.
Old 12-23-2011, 02:05 PM
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

Looked at the fins arrangement more closely and it's different setting then usual for sure. I see you have both outer fins with split rudders in 2 segments, top and bottom similar as S Connie yet different. Then i noticed that one of the two inner top fins have split rudder on it vs other one is plain fin!, correct me if i'm wrong here in my observation. So is it safe to say that both OB fins do main part yet right top inner fis is just used for extra trim purpose. What i find really weird with this design is that it's not a big plane, yet it needs so much rudder area being a twin engine aircraft, i wonder how much adverse yaw is needed to counter it and how much thrust is produced from those propellers for need of so many fins and rudders....
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Old 12-23-2011, 03:18 PM
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chymas
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

I will have 4 vertical stabilizers with the outboard being full length and the inboard being just the upper section. The inboard left hand is stationary with no rudder or tab, the inboard right hand has a functional rudder and tab with 16 deg deflection on the rudder and an additional 16 deg on the tab when moving to the right and only 2 deg on each when moving to the left. the outboard rudders and tabs top and bottom on each side have 20 deg deflection on both the rudder and tab in both directions.

Iwill be using high torque servos for rudders and elevators.

I plan to upload some photos later this evening.


ORIGINAL: Props4ever

I like to see how you will build this model, i'm having hard time with 3 fins and 5 rudders on my Connie, here you got 4 fins and how many rudders........

It sure is different subject and i like it, you will have to watch ur weight in the tails, it wont take much to have tail heavy airplane specially with not too long fuse in front of the wing....

Good thinking for adding functional tabs on the tailplane, those will help in reducing weight by use of mid to high range servos instead of using all MG servos. I did same on my Connie, this way i'll use high torque but non metal gear servos on the rudders but will use single MG servo for both elevators.
Old 12-23-2011, 09:38 PM
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

I'm waiting to see ur build. Since ur going to be making functional trim/boost tabs, you really don't need to use MG high torque servos as nylon gear high torques will do the job due to less air pressure of the surface of OB rudders.

Now why is that the IB right fin's rudders deflect soo much on one side and barely on other?, yet left IB fin is stationary!!...
Old 12-23-2011, 10:30 PM
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound


ORIGINAL: Props4ever

I'm waiting to see ur build. Since ur going to be making functional trim/boost tabs, you really don't need to use MG high torque servos as nylon gear high torques will do the job due to less air pressure of the surface of OB rudders.

Now why is that the IB right fin's rudders deflect soo much on one side and barely on other?, yet left IB fin is stationary!!...
The tabs move in the same direction as the rudders and are essentialy the same size, the control linkage is hooked to the rudder and the tab is controlled mechanically by a pushrod that is cross connected between the vertical stabilizer and the tab, thus more surface and more air pressure. I will need a 120 oz. servo for each outboard rudder.

The reason for the difference as explained to me by a Grumman Tech Rep is due to the torque factor of the props, losing the RH engine is not as critical as losing the LH engine. With the left engine running and providing your only source for power you have the p-factor pulling you to the left while having it running pulls it to the right. The nacelles are also angled out 2 deg on each side.

Included is an overhead of the rear empennage
<o></o>
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Old 12-23-2011, 11:16 PM
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

Ok now i get it, so really u r adding more air pressure on the rudders surface area by adding on more deflection by to increase the air pressure Vs reducing as i've done on my S Connie's rudders. Ur aircraft is very interesting design and a project, it will be real challenge building as a model. But least good part is that you will be dealing with 3 fins with rudders vs 4 as it look like soon as you see this aircraft.
Old 01-04-2012, 04:20 PM
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

Looks Nice Clark.... Real Nice...

Look forward to seeing it come together


Inspiration when you become frustrated
http://www.youtube.com/watch?v=5F86ART6R-g

I have a great walk around pic set of the 50th anv. VRC-40 aircaft if you desire to really spice up the paint scheme



Cheers,
Dave
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Old 01-04-2012, 10:14 PM
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chymas
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

Thanks for the cool video link, I think I saw a few VRC-30 birds in there. I will do my best to post pictures of my progress on the fuselage tomorrow night.

I would love to get some pictures of the 50th anv paint scheme. I am planning to do mine in the VRC-30 new tail design paint scheme, when I was there we just had a big RW on the tail.

Clark

ORIGINAL: HO-229

Looks Nice Clark.... Real Nice...

Look forward to seeing it come together


Inspiration when you become frustrated
http://www.youtube.com/watch?v=5F86ART6R-g

I have a great walk around pic set of the 50th anv. VRC-40 aircaft if you desire to really spice up the paint scheme



Cheers,
Dave
Old 01-05-2012, 07:45 PM
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chymas
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

Ok, as promised here are a few pictures of my progress so far. These are a couple of picutures from the front and rear. The formers are 1/8" lite ply, the 3 formers in the wing area will have doublers on each side with birch ply. Stringers alternate between 1/8" and 1/4" balsa with the top two 1/4" stringers being laminated 1/8 X 1/4 bass wood. I plan to make the rear cargo doors open. Once the left side is complete I have some jigs that I will be using to turn it over and reclamp so that everything is true for building the right hand side.

Above the fuselage is the engine nacell plug that I will be using to make molds and then my fiberglass nacells.
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Old 01-07-2012, 04:45 PM
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

Clark,
Still looking for the pics… wife has 39000 pics on the computer and I did not name them properly (LOL).

Like the progress, please be mindful of the formers at the wing junction, the real aircraft has a significant load bearing former in the load path. As you must know the center wing box beam is under great stress as it is transferring the landing loads and absorbing the fuselage inertia loads into the wing.

The tail arrangement is a function of the Essex class carrier requirements… Basically the carrier elevator and hanger deck could not accommodate larger aircraft of the day, no longer an issue with the new carriers.
The short tail moment arm and the aircrafts single engine rate of climb requirements also require the tail to be of the shown proportions.



Don’t forget the pneumatic landing gear extend circuit for take-off…
Lot of love in that project... keep up the great work!
Dave
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Old 01-07-2012, 06:29 PM
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

ORIGINAL: HO-229

Clark,
Still looking for the pics… wife has 39000 pics on the computer and I did not name them properly (LOL).

Like the progress, please be mindful of the formers at the wing junction, the real aircraft has a significant load bearing former in the load path. As you must know the center wing box beam is under great stress as it is transferring the landing loads and absorbing the fuselage inertia loads into the wing.

The tail arrangement is a function of the Essex class carrier requirements… Basically the carrier elevator and hanger deck could not accommodate larger aircraft of the day, no longer an issue with the new carriers.
The short tail moment arm and the aircrafts single engine rate of climb requirements also require the tail to be of the shown proportions.



Don’t forget the pneumatic landing gear extend circuit for take-off…
Lot of love in that project... keep up the great work!
Dave

Hi Dave,

Your explanation that i highlighted pretty much sums up my question why this aircraft had to have so many vertical fins when it's not that big of an aircraft!. Now i know, it had all to do with carrier elevator and hanger deck height of the carrier from that era ie: Essex class carriers.

Thanks a lot for clearing this up.

Clark,

First half of the fuselage is really looking good, all formers are glued nice and straight, all look square to the top of the table ur building it on. I see ur not a newbie when it comes to scratch building these models.... lol

Keep building here, i'll be watching you build as it progresses further n further...
Old 01-10-2012, 09:58 PM
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chymas
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

@ Dave - I agree with you on the wing junction, I am planning on using carbon fiber as well as tripling the fuselage cross sections in that area. I am also building the plane so that the fuselage, inner wing sections and naccells are all one piece. The wings will come apart where they traditionally fold supported with 2 carbon fiber tubes. Overall width will be around 40", the same width as the horizantal stab.

Correct me if I'm wrong, this is more of a question - isn't the landing gear extend function for carrier launch only?

@ Props4ever - thanks for the encouragement. Ihave built several kit planes as well as repaired a few. To be very honest with you this is my first scratch build EVER. Since leaving the hobby almost 20 years ago and then getting back into it I am finding good kits are gone and to have the plane(s) I like, I will have to build them myself. I have studied many, many plans of large scale builds and have several sets of plans. It may have been a better idea to build one of those first, but my history with this plane kept pulling me this dirrection. I have spent the past year drawing the plans for this plane, as it is starting to take shape I continue to find small adjustments here and there to make it all come together clean.

Old 01-22-2012, 06:52 PM
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

I have been working on building a plug for the engine nacelles. I had cut-a-way drawings of the nacelle stations; I cut out each of the cross sections and then glued them at the appropriate spot. I then cut foam filler blocks to keep the need for body filler at a minimum. When I first started I was having a reaction with the foam and Bondo not liking each other very well. I solved that issue by spraying the foam with primer and then a heavy coat of paint.
It wasn’t too long before I figured out Bondo is much easier to work with on a car than it is on something like this. I set the project aside and moved on to other things while I looked for a better solution. I saw where car makers model their new car designs using modeler’s clay so I figured that I would give that a try. Red modeling clay is very easy to work with, it forms and smooth’s out really nice. My first attempt I completed one side and then left it to dry. What I found the next morning was disturbing to say the least – the modelers’ clay shrank while it dried. I am now on my second attempt at the modelers’ clay. To prevent what happened last time I used a paintbrush to brush water on the plug before adding the clay. After getting one section done I wet a paper towel and placed over the clay to prevent it from drying too quickly (tip I found from a clay website). We will see how it turns out in the morning.
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Old 01-22-2012, 11:55 PM
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

Why r u working so hard to make those plugs with bondo n clay n stuff!...easy way would be to make templates of the Cross sections of the nacelles and cut them out of the foam with hot wire cutter!, then glass n prime them n you have ur plugs.....
Old 01-23-2012, 06:26 AM
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound



ORIGINAL: Props4ever

Why r u working so hard to make those plugs with bondo n clay n stuff!...easy way would be to make templates of the Cross sections of the nacelles and cut them out of the foam with hot wire cutter!, then glass n prime them n you have ur plugs.....
The main reason is I don't believe I can put the detail I want into the foam. If the plug is made exact with pannel lines and cooling ducts my molds and the final nacelles will have all the same detail.
Old 01-23-2012, 10:43 AM
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

Wait...you will juss make basic plug of the nacelles first out of foam, after you have fiber glassed them then you will add details as panel lines using primer technique to do so on the outer surface. If there are small air intake wents those can also be added later on before making the mold on these plugs.

Its a step by step process to do properly depending on the type of nacelle is...
Old 01-24-2012, 02:41 PM
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

Looks good Clark,
Use what ever method that you feel comfortable with is my moto... wood is my forte.

Just an FYI... will be putting together the landing gear mechanical scheme soon and lasering out a prototype.

Be strong and stay motivated!

Gods grace,
Dave
Old 01-28-2012, 06:05 AM
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

Mail Call!!!! Totally my favorite airplane. She meant mail, fresh lettuce, and new movies!!!!

Looking good!!!
Old 02-19-2012, 12:54 PM
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

Laser cut scale MLG for motivation

Dave
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Old 03-06-2012, 08:11 PM
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

I used a router and cut some slots in my building board, built some blocks along with all thread and wing nuts to clamp everything in place. I removed the left hand side of the fuselage off the building board flipped it over, got it secured back down and started putting the right side formers in place.

<o></o>

One of the well respected builders of our club saw the problems I was having with building the plug and suggested a product called Super Fill. This stuff was amazing once if figured out how to use it. The best way is to form it as close as you can before letting it set up. It takes about 8 hours to cure so there is plenty of time to work with it. Thanks for the tip Ron.<o></o>

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Old 03-06-2012, 11:10 PM
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

Wow looking great, i was thinking that its been a while that u haven't posted any updates n ill pm u tonite but you just posted ur update, so its great to see ur making progress.
Every time you work with half sides, you will need to make a jig to build opposite of it by flipping it around, or you could make 2 halfs separately n then join them at the end..
Old 03-15-2012, 11:11 AM
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Default RE: Scratch Build - 1/8 Scale, C-2A Greyhound

Wonderful project Chymas.

This thread will teach me a lot as I was also planning an smaller scale electric C-2A Greyhound, 48" WS with little modification on wing to increase wing area a little bit. Currently I am working on the CAD. I don't have enough skills to work with Balsa so I will build this plane mostly out of foam. I will start a new thread in electric section once I am ready. For the mean time, Below are few screen shots of my progress.

Keep us updated.
Cheers.
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