wowplanes

I have always been particularly fascinated with the A10 Thunderbolt aka The Warthog. Around 4 years ago I had designed and kitted a 62" span model. That was before I got infected with the scale virus, so that was more of a fun scale design. It turned out to be an amazingly easy plane to fly, very manueverable and stable, and easy to land. Ever since then I have been wanting to do a scale version, and so here we are.

While at it, I thought it would be nice to scale up to an IMAA legal Big Bird size. For a jet, IMAA rules require that the sum of the wingspan and the length be at least 140". A wingspan of 73", yields a fuselage length of 67", which adds up to the magical 140". So that's where we are headed. At 73" span it is a 10.5% scale.

I could have made it bigger, but decided to stay with 73", a size that can easily be transported in most cars and yet be eligible to participate in Big Bird events. The other consideration was cost.

HISTORY
The A-10 Thunderbolt II is an American single-seat, twin-engine, straight-wing jet aircraft developed by Fairchild-Republic in the early 1970s. The A-10 was designed for a United States Air Force requirement to provide close air support (CAS) for ground forces by attacking tanks, armored vehicles, and other ground targets with a limited air interdiction capability. It is the first U.S. Air Force aircraft designed exclusively for close air support.
The A-10's official name comes from the Republic P-47 Thunderbolt of World War II, a fighter that was particularly effective at close air support. The A-10 is more commonly known by its nickname "Warthog" or simply "Hog". As a secondary mission, it provides airborne forward air control, guiding other aircraft against ground targets. The A-10 is expected to be replaced in 2028 or later.

DESIGN
The A-10 has superior maneuverability at low speeds and altitude, due to large wing area, high wing aspect ratio, and large ailerons. The large high aspect ratio wing also allows for short takeoffs and landings, permitting operations from primitive forward airfields near front lines. It typically flies at a relatively slow speed of 300 knots (560 km/h; 350 mph), which makes it a much better platform for the ground-attack role than fast fighter-bombers, which often have difficulty targeting small and slow-moving targets.

The ailerons are at the far ends of the wings to gain greater rolling moment, as with many aircraft, but there are two distinguishing features. First, the ailerons are larger than is typical, almost 50% of the chord, providing improved control even at slow speeds. The aileron is also split, making it a deceleron.

The sturdy landing gear, low-pressure tires and large, straight wings allow operation from short rough strips even with a heavy ordnance load, allowing the aircraft to operate from damaged airbases. If runways are damaged in an attack, the A-10 can operate from taxiways, or straight roadway sections, such as Germany's autobahn.

DURABILITY
The A-10 is exceptionally tough. The aircraft is designed to fly with one engine, one tail, one elevator and half a wing torn off.

The A-10's main landing gear is designed so that the wheels semi-protrude from their nacelles when the gear is retracted so as to make gear-up landings (belly landing) easier to control and less damaging to the aircraft's underside. A belly landing would be required in the case of a landing gear failure. Additionally, the landing gear are all hinged toward the rear of the aircraft, so if hydraulic power is lost the pilot can drop the gear and a combination of gravity and wind resistance will open and lock the gear in place.

There are several reasons for the unusual location of the A-10's General Electric TF34-GE-100 turbofan engines. First, the A-10 was expected to fly from forward air bases, often with semi-prepared substandard runways that presented a high risk of foreign object damage to the engines. The height of the engines lowers the chance that sand or stones will enter the inlet.

I am ready to get started with the build. The plastic set is here. Here are pictures of how it will all come out-of-the-box. Plenty of foam and plastic here.
In the manual, I always include the 3 view drawing that was used for designing the model. The builders can use this for details and for making templates if necessary. The picture can be printed and blown up to the size of the model and then any template can be cut from that.

Fahim

rcmiket

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Mike

gary41

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Suscribed, also!![sm=thumbs_up.gif]

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Since my kits use a somewhat different construction technique than the traditional balsa frame method, I have been asked by a few readers to do a very detailed build. That means a lot of pictures and words. It will slow me down some, but hopefully it is worthwhile.

I officially started the build a couple of hours ago, with the fuselage. The fuselage is made up from 3 foam and 5 plastic parts. The foam parts are soft at this stage. To prevent damage, I spread a piece of foam mattress liner over the work table & handled the parts with TLC. I bought a queen sized liner for about $20, that should last me a lifetime, a worthwhile investment, I think.

Before the foam parts can be assembled together, I did some prep work, starting with the cockpit section. The glue used is 5 minute expoxy. Since epoxy and foam are both petro-chemicals, they work well together.

The next step is to prepare and mount the plastic nose cone and gatling gun.

Fahim

wolfy888

I like it. When I moved to Myrtle Beach, SC in the late '70's, the AFB here was still operational, and the first job I had was sanding and painting the 72 A-10's stationed there, so it has always had a special place in my heart. It's on heckuva tough bird, and I sure wouldn't want to be on the wrong end of that GE gatling cannon. Depleted uranium shells can do some awesome damage. Also, you forgot to mention that the pilots like it because the titanium bathtub surrounding them makes for a (relatively) safe combat environment. Several of my buddies swear by its durability, and none of them have returned with gunshot injuries from ground fire. I'm looking forward to build updates, and may order a kit before long. Keep 'em coming, and good luck!

wowplanes

wolfy888, you are quite correct. The A10 is a real man's plane.

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Made some more progress this afternoon. I think I have done enough damage for the day and will stop to enjoy the world cup soccer games that I have taped all day.

Fahim

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Sorry I forgot the attcahments, here they are.

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More progress this morning. Finished the hatch cover retaining system at the front and fitted the canopy and shaped the front end.

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I can only upload 12 pics per post, so here are the remaining ones.

rcmiket

Do have a "target Price" for this?
Mike

wowplanes

I am waiting for the final quotes from my suppliers to fix a price, but my target is $349
Fahim

wowplanes

Well the retracts are sold out and I am waiting for the supplier to deliver the next batch. Also I discovered that the gun dimensions are wrong and some plastic rework will have to be done. For now, this is as far as I can go with the Fuselage cockpit section and the nose. I decided to prep the fuselage wing section. This section is pretty easy to so and did not take much time. That's it for the day folks.

Fahim

wolfy888

LOoking good so far, Fahim. If I can lay hands on my dad's digital camera, we have an A-10 on display here at Warbird park, on the former AFB. Tell me what you need pics of, a nd I'll try to get them for you. This one, MB 097, I have personally painted twice, but the paint on it now is from a professional refitting company, so it's gloss, and doesn't exactly match the TEC order that I painted them from, but it's close enough to the original "Lizard scheme" that we did. The engines are gone, of course, and the canopy has been blacked-out, but the airframe is in pretty good shape for a public location. Especially useful to you might be the landing gear pics, since most folks don't know that the nose gear is far offset to the right side, in order to clear the gun. Talk to me.

wowplanes

Thanks Wolfy. I collected a truckload of info before I had started the design. What is the "lizard Scheme"?

wolfy888

Most of the MFR's have a "Green Camoflage" paint scheme available - it's close, but inaccurate. Look in a string here for "A-10 warthog for $95"; it's way early in the string, and someone posted the original technical order that we used to determine what color went where. I've lost my copies over the years, so it was a real surprise to see that. There are two shades of green, and one of a dark grey, and then all the tech markings in flat black. The paint we used was a (then) classified two-part epoxy that was formulated to reject radar signals - pretty neat stuff for the time. I remember it stank like hell for about two days. Anyway, the tech order that appears in the string I mentioned is the real one - I'd never forget it, because I had to look at it every time before loading the spray guns.

wolfy888

Fahim, it's post #721, from TonyA, on page 29 of the string. He also showed some tech orders I haven't seen before, but the ones I used are the last two sheets. Hope you find this of use.

wowplanes

Thanks for the info. It was very useful.

I have not decided on the color scheme I am going to go with. I like the grey one but my eyes are getting old and I can't see it well against a grey sky. The green does not stand out against the green grass I fly off. The desert camo looks good but I already have this typhoon in that scheme. Decisions, decisions. May be I will toss a coin

Meanwhile my good friend, Frank Tiano of Top Gun fame, has a documentation library that is believed to be the best in the country, if not the world. He has kindly allowed me to borrow everything he had on the A10, which is a lot of stuff. I am wading through that as we speak.

Fahim

wowplanes

Did not spend much time on the build today, but managed to get the tail section prepped. Pretty simple too. Next we assemble the whole fuselage. The kit is designed so the wing and the tail will both be removeable.
Fahim

wowplanes

Now that we have the three fuselage foam sections prepped, it is time to assemble the fuselage. Since I don't have the retracts as yet and the gun is being redesigned, that is as far as I can go with the fuselage for now. Maybe I will start the wing next.
Fahim

wowplanes

Since I am only allowed to upload 12 images, here are the rest.

wowplanes

I was going to put the fuselage aside for now and start on the wing, and get back to it once I have the retracts and the gun. On second thought, instead of storing it in a soft foam form that tends to get dinged and dirty, it would be safer to skin it and harden the surface with LS.

So first we have to prepare the surface. The foam cutter leaves a hard crust on the foam surface and there may be a few wire marks here or there. Only light sanding with 150 grit is required to knock off the crust and level any ridges. The idea is not to get a "baby bottom" smooth surface, but rather a flat enough surface for the balsa skin to make good contact throughout. If necessary, I use lightweight spackle or Foam Putty from Woodland Scenics Inc, to fill any dings. I was introduced to the foam putty by someone at RCSB and find it to be better since it is specifically made for foam and sticks better to it.

I will be using 1/32" balsa as the skin. Traditionally we have used 1/16 or 3/32 but since we have a smooth and level enough surface to start with, why add weight, work, and cost? 1/32 is easy to bend and does the job. I could skip the balsa and apply LS directly to the foam as I have shown with my other builds, but in this case I wanted more structural strength, especially around the tail cone where the heavy motors are located.

The adhesive I will be using is M78 spray from Monsanto. In the past I have used M77, but that is not foam safe, and unless it is sprayed in a fine mist and not allowed to puddle, it will eat the foam. M78 is a new product and is specifically formulated for use with foam and is therefore quite safe. It is not commonly available as yet, but I was able to find it at Amazon.com. They claim that one spray can will cover 100 sq ft which should be more than enough for the whole model. I ordered 2 for posterity.

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Whoops forgot the attachments. Here they are.

wolfy888

Fahim, if you will kindly show us a pic of the nose gear installation, or (proposed) cavity, I think I can get you some pics to help with the scale location. If I remember right, there is also a radome mast very nearby the nosegear well, so it would do you well to check it out for scale accuracy. If I can get the time this weekend, I'll go see, and post pics if I can get them. Wolfy888

wowplanes

Wolfy,
I don't have the retracts, they are on order, so I have not cut the cavity as yet. I will show pics and details when I get to that point. Meanwhile, your pics will help tremendously. Thanks

Fahim