Another build looms. 20cc Seagull Stearman 72"

[Mike.K 60]

I like these Seagull kits. They are very complete and fly well. They are excellent value for money and you would be hard pushed to build from scratch at the price. For speed of construction and with the core parts built and covered, they make a good choice for a time limited constructor. Now under my belt are the two other Seagull kits I`ve already built, namely the Bowers Fly Baby monoplane and the now out of production, Miles Sparrow Hawk. The big 72" Stearman pulled at my heart strings so I now await delivery which is likely to be after Christmas. Presently the kit is on a slow boat from Ho Chi Min City, Vietnam.

A two flight only, used SC180 FS which shares the same crank case dimensions as a 150 has been sourced for a couple of hundred pounds from eBay. This should power the model well and I decided on this power route as this model needs an appropriate sound track and the costs of buying one of the electric 4-Max 6366-270 motors, a 90a ESC not to mention stumping up for something like a 10S, 6000mAh Lipo pack nearly doubled the cost of the build bill. As it stands with the reasonably priced SC180 and the cost of the kit, that alone equates to around £520 with servos, battery and receiver adding to the cost. The 180 route appeared to be the most economic way to proceed.

The two attached images depict this Seagull model. Sadly the original full sized Red Baron Pizza example together with one other example which formed part of a four aircraft display team in the US, is no more. Two of the team collided during an airshow with both pilots being fatalities.

I`ll add to this thread as things progress.

Mike

[Mike.K 60]

Putting the cart before the horse, I bought a two flight only, used SC180FS complete with a nice pair of engine bearers from an eBay seller for £210 delivered. That`s about a £120 saving from buying new. I couldn`t let such a low time engine slip through my fingers. Images below. As you can see, the unit is almost unmarked.

As regards the Seagull Stearman kit itself, that is on the slow boat from Vietnam and expected to be in stock with J Perkins at West Malling on 23rd December 2019. Delivery before Christmas seems unlikely. At least that gives me further time to accumulate the necessary and expected costs of more than £300. It will be a nice New Year present all be it an expensive one. Pleasingly, I`ve ordered through Rob at Avicraft.

Mike.

[Mike.K 60]

On advice from Martin Wood, I`ve just ordered an onboard programmable glow plug activation unit which will be powered by a separate NiMh cell. This permanent fixture allows plug power for start up and also whilst slow flying with the engine running at slow speed....in other words it keeps the glow plug alight at low throttle openings which is when the engine is most likely to flame out. I see that as additional security when on the landing circuit. There is nothing worse having an engine stop at the wrong time! This Stearman will cost nothing less than £650 to get flying so its an expensive investment to risk. Having a powered glow plug unit aboard seems like sensible insurance against a potential motor stoppage. Here is the link to the RCD3007 unit I found on eBay for £23.RC Remote Glow Plug Starter Igniter RCD3007 With Alarm Nitro Engines Planes Cars

I`d be interested in comments from anyone who has used this or a similar unit on their own model(s)

Mike

[Mike.K 60]

Rob at Avicraft managed to get a kit delivered in time for Christmas. It came in a whopping great box full of goodies. I was well pleased.

The core build progressed rapidly until I hit the first of several issues. Then the trouble started....

1. Three rear cabane struts and only one port front one was included in the kit. I was forced to make up a temporary substitute until Rob could get Perkins to open up another kit and cannibalize it for the part I needed. The replacement strut was sent by post to me immediately but that too was incorrect. In frustration I drilled new holes in the replacement offending part and once again Perkins were be informed.

2. The aggravation really cranked up after the model was built up. The tail-plane unit which measures some 30"/770mm in length was noted by me as being noticeably heavy straight out of the box. I also noted servos were installed rearwards in the fuselage directly under the rear pilot. In my bi-plane experience, servos are usually installed right up front roughly on a line with the leading edge of the lower wing. I continued with the build trusting that Seagull had this matter cracked. Alarm bells began again when I marked up the CofG 100mm rearwards of the leading edge of the top wing having installed batteries, engine and cowl. Lifting the model saw the tail wheel stay well and truly on the table. Odd I thought. Having previously worked on full sized Stearman aircraft thirty years ago, I always understood the C of G on a Stearman was derived by initially horizonally leveling the fuselage longitudinally. Then a vertical a vertical line would be extended at 90 degrees from the horizontal fuselage datum upwards at the leading edge of the lower wing. A plum bob hung from the top wing was aimed at the lower wing leading edge. This defined on the top wing the aircraft C of G. With care, the method was fool proof. That is how I`d always check a Stearman if it came to us for a Star Annual 3 year tear down and overhaul. On this model I slopped 1.3Lb of lead shot encapsulated in an epoxy/silica/cotton fibre slurry mix into the lower front edge of the cowl and let it cure over night in front of a blower heater. Next morning, I refitted the cowl. Lifting the model at the 100mm mark on the top wings still left the tail wheel in the deck. Cussing the designer madly, I decamped to Rob for advice. Before I left home, I cut another 1Lb of lead from my roll of roofing flashing and took that with me to the shop together with the model.

At Avicraft, the model was bumped up on Robs counter. Rob soon had a handle on the nature of the problem. Heavy tail-plane and aft fitted servos. I dumped the 1Lb sheet of lead atop the engine cowl to demonstrate how much lead was needed to attain the manufacturers stated CofG position. What!!! 2.3Lbs of lead dead weight!  You must be joking. Somebody is having a laugh!! Dear old Barry and Doug arrived in the shop and the matter was further discussed. Rob got on the phone to Geoff at J Perkins and we also looked at the RC Universe site to see what other builders of this model suggested. One post said the model Cof G was crazily and and excessively nose heavy. Rob and Geoffl recalculated using a similar method I had used on my little SFM Se5A. We re-calculated the C of G to be an inch further aft that stated in the Seagull manual, unscrewed the servos and moved them forward. It became patently obvious that the servos would have to be moved forward and wire tail end push rods extended. I felt my patience slipping. As Rob and I lifted the model with our fingers on 125mm marks under the upper wing tips, to our joy, the model balanced sensibly. That position equates to balancing directly under the main spar of the upper wing.  The 125mm mark is also set at the leading edge of the lower wing. Something I need to do before this model is test flown. I must double check that prior to first test flights. Needless to say, the 1Lb sheet of lead became and unused dead weight and I couldn`t be bothered to bring it home. Now left in Robs care! My sincere thanks to Rob and others for helping solve this conundrum. One thing is certain, as agreed, I`ll be mailing Perkins (who were highly concerned at this development) and recount the whole saga. Young Ollie at Perkins says they speak to Seagull about an kit issues and this saga is certainly something they should know about.

3. The tail-plane on this model IS excessively heavy. Note well.

4. Grub screws on the wheel pant collets require replacing with cap screws in order to get them properly tightened. Otherwise they slip and the spat rotates around the axle. Yes, I did put a flat on the axles!

5. The sprung oleo legs are not well made. A tremendous amount of toe in and toe out occurs torsionally. This could well cause tracking difficulties on take off and landing. Again Seagull need to be told about this problem.

6. The starboard elevator outer snake was badly mis-aligned with the control wire exit slot at the rear of the fuselage. It took me half an hour of buggering about to get that control wire push-rod to make an appearance at the aft end.

7. The ply inter-plane struts whilst made from quality material were painted orange rather than red. I had to cover them in the appropriate shade of Oracover in order to match the red trim on the rest of the model. Similarly, the rudder appeared to be a differing shade of red to the rest of the trim on the model. This is due to the rudder only being covered in red film whilst the remainder of the red on the model was applied over the base white covering.

8. The epoxy glass  cowl is spray finished to a high lustrous red over white gloss paint. That`s nice..... BUT but the cowl is pathetically thin. Rob suggested I lay another layer of 200gm/square metre e-glass within the cowl to beef it up. In its ex-works state, I`m sure the cowl would have split soon after a couple of rough landings.

9. The makers C of G position is 25mm too far forward and build instructions need amending as does the servo plate cut out positions. In addition, longer push rod piano wires for the elevator and rudder linkages are needed.

What perhaps surprises me most is that this Stearman kit has been in production for quite a few years. RC Universe forum posters have noted some issues including the wayward C of G position. One has to ask? Hasn`t anyone had a moan about similar issues to the ones I`ve experienced and why have not Seagull modified the kit to improve the situation? As readers of this thread might appreciate, the kit build turned out to be a minor nightmare. Other than the above recounted issues, the kit was good to build but requires and advanced builder experience to complete successfully. It certainly isn`t a beginners model. I don`t think I`ve been harsh about this kit build. It`s 98% good but the remaining 2% has been rather un-satisfactory.

I`m now in the process of cutting out cowl material to enable the silencer to poke out through the bottom. Then the model is near finished and only requires decals to be applied. More details in due course.

Mike