Warbird Information Exchange

I might have an opportunity to fly a 450 Stearman (R-985). I have a fair amount of biplane time and some in the stock PT-17. Anyone who has flown both care to share what to expect from the R-985 bird other than better takeoff performance? How does it handle on takeoff/landing compared to the W-670 Stearman?

I think it is nose heavy.

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Scott 'Gunny' Perdue
http://www.eagleflyingmuseum.org

Thanks Gunny. Does the heavier nose do better with wheel landings?

I found the stock PT-17 like three-points best.

We had a stock 220 hp. PT-17 that my dad kept for 23 years. Then a year later he took in a 450 hp, PT-13 on trade. It has been about twenty years but here's a few notes. The 220 hp. cruises at 100 mph if you have a strong engine. Ours improved from 93 statute mph to 98 mph after new fabric and re-rigging. 13 gph. on the stock Stearman. Our 450 had an R-985-AN1. this engine was used on the UC-43 Traveler (Staggerwing) , the BT-13 and a few others. It's a two speed prop; Climb and Cruise. It seems like the cruise speeds on the two choices were 105 and 121 mph. Fuel burn on ours was 23 gph. If you reduce power below that , it would be in the vibration range and would start shaking the whole aircraft. The constant speed prop would be a nice upgrade as to give more performance on less fuel burn.
The STC on ours only allowed for 300 hp. on takeoff. Of course it does fine holding the brakes and running up to max allowable MP and then zooming off at a better than Supercub climb rate. It climbs like a beast and I couldn't resist doing those max power take offs almost every time. Fuel burn shoots up to about 44 gph. on that power setting. The ex crop dusters 450's will have the exhaust at the 3 o'clock midwing position. The nicer mods have redirected this straight down where the belly of aircraft shields a bit of the noise. even with double hearing protection, my ears would be ringing the rest of the day after a 30 minute flight.
It seemed to fly about the same. In cruise prop setting, 121 statute mph, the windscreen isn't that effective, Remember goggles vibrating on face to the point face becomes very itchy. There was a 5 gallon oil tank located in the baggage compartment to move the C.G. to the proper location. It seemed to land about the same but has a higher sink rate. Practicing dead stick landings is not for the feint of heart!
the 450 is a wonderful airplane. Only negatives I can think of would be the extra fuel burn and the shorter time in the air if you stay with the original 48 gallon tank.

Generally, in the air the are still the same airplane. You'll notice the 450's ailerons are a little heavier due to the higher cruise speed (assuming it is a stock 2 aileron airplane) and it might be a bit windy-er in the cockpit, but other wise basically the same in cruise. If you run about 20" & 1750RPM you'll be flying a 220

The real noticeable differences come in takeoff and landing. Takeoff is principally the same as a 220, it just lasts 1/4 the time and you climb great once you're off the ground. You'll have a power reduction to make on climb out but otherwise it is all the same. Landings are a bit different too. The airplane is definitely heavier so it won't float like a stocker. Most 450's are about 300-400lbs heavier than the average stock airplane. I fly final a little faster (maybe 75-80mph instead of 65-70mph) and carry just a touch of power to make up for the sink rate and give yourself a little time to "feather" the flare and roll it on. As Marine Air mentioned, complete power off landings (or emergency simulations) are radically different than a 220, a 450 airplane falls like a rock. I've had people not make the runway from a mid-field downwind simulated engine failure

The biggest thing about a 450 is that they are all custom modifications - there isn't a "stock" conversion so they are all different. There are common methods and approaches that people take making many 450's somewhat similar, but they are still all different. How much weight is in the tail and where the CG falls makes a HUGE impact on the airplane, as well as what other modifications were done with the 450 conversion.

Whatever you fly though, it'll be a blast.

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Ryan Pemberton
www.pembertonandsons.com

If I recall correctly aren't 450 Stearmans supposed to be placarded against doing snap rolls?

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Defending Stearmans on WIX since Jeff started badmouthing them back in 2005.

They are placarded "Spins Prohibited" but nothing about snap rolls (unless you take it very literally that a snap roll is really a one-turn horizontal spin!) However, doing snap-rolls on a regular basis on any R-985 powered airplane is pretty ill-advised. I know several current airshow performers get away with it but they are all running the much lighter 3 bladed Hartzell props (although I still wouldn't personally). There have been many crankshaft failures due to this. In fact, this is what killed several of the 450 Stearman airshow guys of the 50's and 60's.

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Ryan Pemberton
www.pembertonandsons.com

I thought the failures had to do with the big prop on the 450 having such gyroscopic force/resistance that it was pulling the studs out of the fuselage frame when guys snapped it?

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Defending Stearmans on WIX since Jeff started badmouthing them back in 2005.

Covington used to shoot peen the cranks & rods for R-985 airshow performers. They said it helped a lot with this issue and cut down on both parts failing.

Certainly the size/weight of a HS 2D-30 is a big factor, that's why all the airshow guys go to the Hartzells (I believe). During a snap you're correct that the gyroscopic forces are huge. I think there have been several failure modes, all with the 2D-30 prop and 985's on Stearmans due to snap rolls. I've heard (2nd, 3rd, 4th, 5th hand or whatever) that:

*Rolly Cole was killed when the nose case catastrophically failed and the prop (some say a lot of the crank too) departed the airplane.

*Bill Adams was killed when the whole engine separated from the airplane and swung up such that the prop cut the cabane struts.

Those are the two really big names that were lost due to this combination, although there has been others. As noted, the modern operators do still crack cranks on some occasion although with the increase in maintenance practices we have to day they get caught before problems really arise. With all of that said, even 985's running Hartzells in non-aerobatic applications crack cranks so maybe there isn't a strong of an association as some people (including me!) think between snap rolls and failures.

Just because we've drifted off topic, we might as well go further off topic with some wild 450 acro fun!
https://www.youtube.com/watch?v=YDv9kBnnD8o

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Ryan Pemberton
www.pembertonandsons.com

Is the R-985 on the Stearman subject to the same 1200 hour tear down inspection as the Twin Beech when the 3-blade Hartzell is installed?

Thanks all for the great info. Hopefully I'll get to experience the 450 next week!

Yeah, that's a 985 AD note and isn't specific to an airframe. The AD requires replacement (maybe just inspection?) of the flyweights and flyweight liners on the crankshaft. Unfortunately that means tearing basically all the way down. At this point, most people just opt for an overhaul as the engine is basically there already.

Note, just google'd it and per the master's website (Covington) they say:
"It must be noted that there is an Airworthiness Directive 68-09-01 issued to the R-985 engine. It is concerning Crankshaft flyweights and flyweight liner replacement. This AD mandates that it be accomplished at 1200 or 1600 hrs depending on propeller installation. In order to accomplish this, the engine must be disassembled to the point it is more economically feasible to overhaul than to limit to repair and replacement only." (http://www.covingtonaircraft.com/faq/wh ... 99s-my-tbo)

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Ryan Pemberton
www.pembertonandsons.com

That makes sense. I've got the two blade HS props on my Twin Beech, so while I don't have to tear the engines apart at 1200 hrs, I get to pull the props every 5 years.

I owned a 42 cont. 220. It was a lot of fun but certainly not overpowered. It did not glide very far and dropped like a stone in a slip. Lots of fun . I was told that when it was overhauled the main bearings were suspect, could fail without warning so be sure and have them replaced with roller bearings. I sold it without doing this. Is this true?