AT-6 reflections
 

I WAS siting here reflecting back on my AT-6 RIDE and thinking about
how Tough that pratt and wit sounded, during my ride.

What is the horse power of that engine?

also in the vid that i got with the ride, i noticed what looked like the pilot
reversed the prop rotation before take off and than put it back to normal
for the take off roll. does it reverse?


i wish my dodge ram sounded like that


thanks

dan

RE: AT-6 reflections
 

The prop will do that on a vid. It doesn't in real life though.

My ride in one was fun too. The guys wife was telling me all about it and the seat belts and stuff. I was looking around not paying attention. She asked what I was looking for. I said "the stick isn't in". She says, "he never lets anyone fly his plane". The pilot turns around and says "hes a pilot, put it in."

He gave it to me as soon as the wheels broke ground. I tucked in tight on the one in front of us that we took off with. Flew about 15 miles and he took it back and said "GO". Huge dog fight. Was a blast. He said "break" and we went back into level flight. He gave it back to me and I tucked back in. Flew around town in tight formation and over the house I live in then. Flew it to short final. What a blast. He said he was impressed. You gotta like that. :D

RE: AT-6 reflections
 

Moire pattern? <== not sure on spelling. I wish my truck sounded like that too! Wake up the entire neighborhood at 5 AM!!!!! hehehe! :D

RE: AT-6 reflections
 

Hi Typhoon MaGoon!; The P&W in the T-6 is 625 hp. Just before takeoff in a constant speed prop plane, you do the normal runup mag check, and while at that rpm, you pull the prop back to low rpm, which is high pitch, (high gear!) to be sure the governor is working, and then back to low pitch (low gear!) for takeoff. This is standard procedure for all controllable prop planes. I've flown the T-6, and that growl is quite stirring!! Lee Robinson

RE: AT-6 reflections
 

You're 25 hp too high. The P&W R1340 is rated at 600 hp. I've got a little over 1,000 hours sitting behind that engine on a B model Ag Cat and 301 Air Tractor. That and the R985 (450 hp) are probably two of the best radials ever produced. Just like any other radial though, they are finicky, and must be cared for and fed correctly.

RE: AT-6 reflections
 

My R985,,,:D
http://images.snapfish.com/34274%3B4...B5447%3Aot1lsi

RE: AT-6 reflections
 

Lowley:

I'll agree on the R-985 being a really good engine. There has been enough experience in the 60 odd years it's been around, the old 800 hour TBO is a thing of the past. Not so with the R-1340.

But the best? That is without question the R-2800. Even the FAA has approved a 3000 hour TBO on them. Granted, it's just a little tiny bit too much engine for a Stearman conversion, or to hang on your Agcat. Still a much better engine anyway.

The R-2800 was, incidentally, built in greater numbers than any other radial engine. The R-985 was the second highest production.

Bill.

RE: AT-6 reflections
 

Oh I agree with you on the R2800... Super engine. I was just referring to single row engines. As far as the 1340 goes, right again, the 985 is the much more reliable of the two, but, we used to get 1000 hours out of our 1340's on a regular basis. Of course, we only used engines that came from Covington or Tulsa Aircraft, and I'm sure their level of quality control had a lot to do with that. Now if you go talking about the geared 1340, I'll stay away from that one.:D I do love the R2800 though, it's probably my favorite radial out there.

RE: AT-6 reflections
 

Not being a full scale pilot I was wondering what the firing order was on a nine cylinder radial and is it the same on all radials. I now they have a collecter ring for exhaust what does it use for intake manifold?

HAPPY NEW YEAR


Lonnie

RE: AT-6 reflections
 

Lonnie:

Radial firing order.

Looking at the engine from the front, pick any cylinder and name it #1. Usually this is the top cylinder, but not always. Makes no difference in the firing order though, you can start an any cylinder and it works.

Starting at your #1 cylinder, number them in order, in the same direction as propellor rotation.

The firing order is then first the odd numbered cylinders in order, followed by the even numbered cylinders in order. So a five would be 1-3-5-2-4- and repeat. The seven is 1-3-5-7-2-4-6- I'm sure you can take it from there.

Radials almost always have an odd number of cylinders per bank, there have been some few made with an even number. It is impossible to get even firing intervals with an even number of cylinders per bank with a four stroke engine, so the engineers just stayed with the odd numbers.

Bill.

RE: AT-6 reflections
 

So then every other cylinder is 90 degrees of crankshaft rotation how do you do that with an odd number of cyl? whats a good book on radial engine basics. thanks for info

Lonnie

RE: AT-6 reflections
 

Lonnie:

Not 90 degrees, no. A five cylinder engine has the cylinders 72 degrees apart, and the firing intervals are 144 degrees. The five 144 degree cycles total 720 degrees of crank rotation, and there is your two crank turns for a complete engine cycle.

The seven has the cylinders at 51.43- degrees, and the nine has 40 degree cylinder spacing. In all cases the firing interval is twice the cylinder spacing.

There is a craftsman's web page on building your own radial engine, and another on the development of the P&W R-2800 engine, but click [link=http://travel.howstuffworks.com/radial-engine.htm]here[/link] for a simple explanation. Want more, come back and I'll direct you to another site.

Bill.

RE: AT-6 reflections
 

Bill thanks for the info. That how stuff works web site is great .I book marked that one. Thanks again and a HAPPY NEW YEAR TO YOU
LONNIE

RE: AT-6 reflections
 

During the early 1950's, my father was a flight instructor for Texas Aviation Industries (TAI) in Hondo Tx. At the time, they were flying T6's, training Air Force students to solo. I remember the training was very vigirous, and they were not allowed to solo until they could exhibit skills in spin, spin recovery and basic aerobatics. They did quite a bit of night flying, and you could hear them for miles when they would bring the engine up to max manifold pressure and exercise the prop. Eventually they went to T28's. Some years later, he solo'ed me in a Champ, and whenever he would tell me to perform a two turn spin, he meant two turns, no more, no less. I've been flying, strictly for pleasure, ever since. Jim

RE: AT-6 reflections
 

Lonnie:

Looking back I see I didn't answer you question about the intake on a radial.

If you have an engine you can look at, you'll see all the intake pipes running to the crankcase. Just inside there is a centrifugal blower, some would think it to be a super charger. While it can be, its main purpose is to keep the intake mixture agitated, so the gasoline vapor does not condense and slog the lower cylinders. The fan is called the "Diffuser." Some smaller radials don't have a diffuser, but I don't know of any that don't use the common chamber in the crankcase as an inlet manifold. None of our model radials, so far as I know, use a diffuser fan.

I've attached pictures of two different Technopower radials, two of a 7C with ignition for gasoline fuel, and tow of a 7A set up for glow fuel.

Bill.

RE: AT-6 reflections
 

Bill thanks again for all of the info. Those radial engines are quit different than automotive engines .I mean the same principle but they go about it in quite a different way.What are the big pros and cons of the radial
HAPPY NEW YEAR
Lonnie

RE: AT-6 reflections
 

I've wondered who was the genius that modified the first rotary to a moving crankshaft, instead of fixed to the firewall, with all that iron stuff rotating around it?
Was it Pratt, or Whitney? :)

RE: AT-6 reflections
 

Lonnie:

Simply put, while the radials are complex mechanically, they have the highest power density of any piston engine. Power density meaning from a given physical size of the entire power plant, counting all the systems, including cooling. The cooling is where the liquid cooled engines lose, but a V-12 like the Allison V-1710 or the Rolls V-1650 Merlin can have much less frontal area, again though, not including the radiator. And liquid cooling adds problems all its own.

In combat there have been many instances of extreme engine damage still making the trip home. Including having complete cylinders shot off the engine. With a liquid cooled engine any major hit will dump the coolant, the engine overheats, you're down. Even a hit on the radiator will kill the engine. Air cooling just gives you a better chance.

On a similar note, the last US combat plane with a piston engine had a radial, the R-3350, in the Douglas AD-1, commonly known as the "Spad."

The Rolls Merlin, and its much larger brother the Gryphon, are common sights at the Reno races, and they go fast. The Dago Red P-51, for an example. But. Rare Bear, a modified Bearcat F6F, has a BIG radial, a P&W R-4360. It's faster even though it has the engine with the larger frontal area.

Sorry for the simplified explanation.

Bill.

RE: AT-6 reflections
 

Paul:

Who made the first radial? I don't know, bit it was neither Pratt nor Whitney.

P&W was a general machine shop, not making aero engines at all, when they were approached about building some as a competitor to Wright. Yes, wright was in the engine business before P&W built their first aero engine.

The oldest fixed case radial I know of was the 3 cylinder Anzani that Bleriot used on his monoplane for the first flight to cross the English Channel.

Bill.

RE: AT-6 reflections
 

Yup, Rare Bear holds the world piston engine aircraft speed record right now, I think 530 mph. Highly modified R4360 up front! You havent heard a radial sing until you've heard that on coming down the front stretch at 500 mph,wide open, 50 feet off the deck!

RE: AT-6 reflections
 

I bet it sounds like heven! Love the sound of the radial

HAPPY NEW YEAR

Bill thanks for all of your info



Lonnie

RE: AT-6 reflections
 

Rare Bear sports a 3350,,, not a 4360,,, http://www.rarebear.com/
A 3350 I get to play with.
http://images.snapfish.com/342768%3A...6%3A9376ot1lsi

RE: AT-6 reflections
 

726:

I remember you talking about riding in that side-by-side Spad. Interesting. But if you check further I do believe you'll find the Rare Bear has all 28 cylinders of the good old "Porcupine" engine.

If your buddy wants to hop up his AD-1 there's a zero timed R-4360 on the "Bay" right now with a buy now price of $6500. Sounds like an impossible price, but that's what it says. Item number 4514721803.

Bill.

RE: AT-6 reflections
 

Oops! I stand corrected on the Bear's engine.:D $6500 for a zero time 4360??? Gotta be a catch somewhere. You cant even touch a zero time 985 for that price. I've got a friend that just spent around $50,000 putting a zero time 1340 on his Ag Cat, so $6500 for a 4360 sounds REALLY fishy to me.

RE: AT-6 reflections
 

Actually every "chopper" you see on TV or on the streets is a radial engine, just two cylinders.

I'll never forget the opportunity I had to fly a T-6. The airport manager at Sidney Airport where we have a fun-fly ever year always gets his out and plays with it. I was lucky enough to get some stick time in his T-6, which was delivered to the USAAC in April of 1940. It actually went to somewhere in the Pacific at some point I can't remember to help in training. Wish I could be more vague...

I went up first about an hour before sunrise, then my dad went up. It was almost dark when they did a low pass at full throttle about 75 feet from where I was standing, about 50 feet up. Now THAT was awesome! Oh and he passed from left to right, so I could see the cool blue flames coming out the exhaust to. Man I wish I had a camera..