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Radial Engine SD 2 final assembly (Rigged before cover)

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John Singer

Joined: 03 Dec 2005
Posts: 131
Location: New London, NH

PostPosted: Sun Feb 06, 2011 9:19 am    Post subject: Radial Engine SD 2 final assembly (Rigged before cover) Reply with quote

Questions re 670-23 radial w CS prop powered Starduster II.

I understand that an oil cooler is not necessary and that it is sometimes difficult to get oil temperatures up to good operating levels in cold weather. Is this true ?

Is cylinder cooling adequate without baffles between the cylinders to direct air to the rear fins ?

What is a typical weight on the tail wheel ? How is it measured, level ?, 3 point position, With or without pilot weight ?

Where is the oil tank and battery normally located ?

As background, my battery weighs 24 pounds and is mounted low on the firewall.

My oil tank holds about 4+ gallons and was fabricated to fit between and partially above the engine mount which is 15.5 inches long to engine mounting bolts.

I would appreciate any information about your 670 radial installation.
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Joined: 05 Dec 2005
Posts: 810
Location: California, Fresno

PostPosted: Sun Feb 06, 2011 8:01 pm    Post subject: Reply with quote

Paul Shafer could answer this.

Paul.... are you listening?

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Starduster History

Joined: 30 Nov 2006
Posts: 736
Location: St. Helens, Oregon

PostPosted: Mon Feb 07, 2011 12:43 am    Post subject: Radial Powered Starduster Too Reply with quote

John Please pvt message me with your phone number and best time to call as there is just to much about this subject to type in with one finger!

I rebuilt N147DA The radial powered Starduster Too that Dave Allen built!

But briefly The -23 is the one W-670 that can have a C/S prop it also has a roller bearing crank.

This airplane did not have an oil cooler nor did it have baffles between the cylinders

The airplanes are generally weighed empty in level flight attitude with no pilot fuel or baggage and N147DA weighed #70 lbs on the tail in level flight.

The oil tank was mounted on top of the engine mount and I think held 3.5 Gallons

The battery was mounted behind the seat and was a standard Gil that weighed about 27# lbs

The engine mount length was 15" from the fire wall to the front face of the mount and had 1.5 degrees of down thrust the ring was from a Stearman.

The airplane also had a fuel boost pump as well as an engine driven fuel pump. and at min fuel the head pressure for a gravity feed fuel system was marginal this is why according to Dave Allen it had these fuel pumps. Also the carb, NA 6? required an accurate float setting and fuel inlet pressure!

I flew this airplane approx 5 hrs and delivered it to its new owner on memorial day 2005 to my knowledge it has never flown since!

It was not a fun airplane to fly I suggested about five different things that needed to be changed that would have made it a much better! airplane the new owner chose not to do any of them!

Paul's airplane was a better flyer but I never flew his so cannot give you a real opinion as to how they compare. His was lighter and had a better prop with a better thrust to weight ratio.

As always this is just my opinion based on my notes and recollection. After we talk I can scan some of this info in and E-Mail it to you.

I wonder about Kevin Shaw's Airplane as we have not heard anything about it or him since he first flew it? But they have been having record cold in that area.

Dave Baxter
Starduster History
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Joined: 02 Dec 2005
Posts: 456
Location: Lynn Haven, FL

PostPosted: Mon Feb 07, 2011 1:24 pm    Post subject: Reply with quote

Can you expand on "It was not a fun airplane to fly"?

Heavy, slow to climb, sluggish handling, slow in roll, unstable in roll or pitch - on the ground, poor visiblilty to the front, I can imagine other bad habits as well?

What changes would you have made that the owner did not prefer?

Are you arguing against round engines on Stardusters?
Cheers, Frank
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Starduster History

Joined: 30 Nov 2006
Posts: 736
Location: St. Helens, Oregon

PostPosted: Mon Feb 07, 2011 3:35 pm    Post subject: N147DA Reply with quote

Frank I will try to explain what I mean by not fun to fly. No I am not arguing against round powered Stardusters. This airplane had several problems that after flying it would lead one to believe that a round engine Starduster would not be the way to go! I think Paul's airplane was much better!

This airplane was heavy and really nose heavy having a 15.18" empty CG! It was the only airplane that I have flown that I felt comfortable using two hands to flair even with full up trim! To be fair I have skinny arms, and I am spoiled by how well my airplane fly's. This was the most apparent thing! My son nick named it "Massive" All of the conventional wisdom that I had heard about the 220 Continental on Stearman"s IE: run them like they do on Stearman's Re: power settings cruise them at 1750 RPM At that RPM the airplane was not happy! The engine lugged and flew tail low, it is hard enough to see around a radial in level flight but flying tail low and lugging along it was worse!

One of my A&P buddies I had worked with on AG Cats that was familiar with round engines suggested that with the prop I had on this airplane I should run it up to 2000 RPM as with this prop 96" Sensench one could run this engine a 100 Rpm over red line and not hurt it! At the 1750 RPM it flew tail low slow and not very responsive!

I did so and ran it up to 2000 RPM and the airplane flew much better and a lot more like mine but still tail low. The airplane needed more negitive incidence in the horizontal stablizer, and I was unable to adjust it in do to the fact that the elevator spar would hit the lower part of the upper longeron limiting its up travel and as I previously stated it required full up elevator one problem that exacerbated this was that the push rod from the reverser behind the seat to the elevator was made to short! This gave about 40 Degrees down and about 20 degrees up when just the opposite was needed! It was a one piece affair similar to the Acroduster with a larger diameter tube. This long single piece tube would have been almost impossible to remove from the airplane after it was covered and all of the other things installed!

The airplane was also very loud do to the exhaust system Stearman type that exited out the R H side of the engine and made it almost impossible to talk with your front seater! The straight down exhaust like on Waco's would be much better and perhaps a better intercom would have helped!

The rudder pedals were after market cast aluminum mouse trap type that had little to poor leverage to the master cylinders if it once got away from you one did not have enough brake or rudder to stop it! Probably one of the contributing reasons along with severe tail wheel shimmy that led to the accident!

Changes I suggested: Longer elevator push pull tube, Lowering the horizontal Stabilizer and Elevator in the fuselage, Different exhaust system that dumped it out under the airplane, Servo trim Tab, different rudder pedals that had a better braking set up, Stronger fuel system selector valve set up as the one in the airplane was springy and difficult to select the correct tank position(Shafts were made out of 1/4" 035 4130 tubing, A longer tail wheel spring and better positive incidence, And possibly adding more positive Incidence to both wings at least a half of a degree 1/2. This is what Steve Wolf did to the first Sampson and this airplane was about the size of a Starduster Too but had a 450 P&W on it!

The owner did not want to spend any more money on it!

This is my recollection, but we need to talk. Dave
Dave Baxter
Starduster History
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Joined: 03 Dec 2005
Posts: 69
Location: Woodstock, Georgia

PostPosted: Mon Feb 07, 2011 10:48 pm    Post subject: Reply with quote

I'm still with you all here in cold Georgia. We've got about 5 hours on my radial duster so far. Me and three other pilots have flown it so far. I've decided to make some changes to it since then but not really because of the radial. I've had to really tweek in the rigging as I had a left wing low condition but have got that straightened out. Swinging a big prop seems to want a little wash in as the old Wacos did but I was a little out of rig to begin with. I built traditional N-struts so this wasn't a problem and she flys great now.
I do have a problem with the elevator being very heavy. I bought this basic airframe from an A&P from KS that built it with the reverser behind the seat upside down (2" on bottom instead of on top) and built in the stops with this. So I am making up some new parts for that. I stopped the fabric at the rear seat back so getting to every thing is easier.
Two other things i'm changing that we all agree on is making the control sticks longer, and, bringing the trim up to near the Quadrant. I have built a lever system like a Pitts model 12 using a Cessna 337 fuel selector assy. i salvaged with lever on it I made. I'll let you know how it works...
Flying throttled back this airplane flys great. I tried 1 degree pos, and 1 degree neg incidence on the rear stab and found 0 degree best for level flight at cruise.
I do have the oil tank behind the rear seat and weight & balance numbers worked out good. Empty cg at 20"
I installed double puck Cleveland brakes with 8.00X6 tires and I can hold full throttle runups on the ground.
I have a PM1200 intercom with push to inercom switches installed which works great.
I'm also working with an annoying cough in the engine at mid throttle as the Stearman guys call the Continental cough but thats another story.
We are still playing with it but everybody so far loves flying her.

Kevin Shaw
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PB Schafer

Joined: 08 Dec 2005
Posts: 185
Location: Oregon, Sutherlin

PostPosted: Sun Feb 13, 2011 11:59 am    Post subject: radial engine SD Too Reply with quote

Hi all, Just dropped by to check up on everyone. I have the following to offer in regard to the post subject:
I found an oil cooler unnecessary, as I had plenty of cooling with the cyls uncowled. Even on the hottest days, I never had a problem with oil temps.

Ditto on cylinder cooling. Tail wheel weight was measured in level config
for W&B. Ground weight is nice to know also.

My oil tank was mounted right behind the engine, and held 4 gals, although I normally ran 3 to help warm up. The original battery was a concorde, but I changed to an Odessy. The battery was located behind the pilot seat.

The engine was mounted 14 1/2" ahead of the firewall. It was swinging a Falcon propeller 90 X 78.

Horizontal was set at Odeg. The aircraft would fly at 100 mph with a power setting of 1700. It flew better at about 1850.

As a note, my airframe was built to standard plans, with the only changes
being my own design airleron bell cranks, and a beefed up landing gear truss.

The aircraft handled well on the ground, and was responsive in the air.
If anyone desires more info, or pictures, PM me, or call me.
PB Schafer
" Just happy to be here !"
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