SLEC / Precedent 1/4 scale Stampe SV4B

[john stones 1 - Moderator]

Lovely build Steve, nice flying also.

[Steve Dunne]

And another video has surfaced - the very first take-off and landing.

Many thanks to Phil Jarman - I thought he was on the phone at the time!

Steve

[Nick Somerville]

A good outing again with my Stampe today and this time with 2-3 oz of lead attached under the tail, taking on the advice of being it being nose heavy. A little livelier in the air with better authority in loops and much less height loss in the spin. Landings just a dream with tail settling down nicely when asked. Happy Days

[Michael Denest]

Nick, have you tried a dynamic Cg test? Go to a reasonable height then dive somewhere between 30 to 45 degrees. Neutralize the stick then watch. If the nose tucks under, it's tail heavy; If it pulls up out of the dive, it's nose heavy.

Steve, excellent job on your Stampe, thank you for sharing.

[Steve Dunne]

Second day out flying the Stampe.

After the maiden last week, I removed 11 ounces of prime church roof (OK, old lead flashing from the bay window repairs!). This moved the CG back 13mm, so that it is now 2mm in front of the plan position.
The dive test shows neither dive out nor tuck under, so I feel that is about right. It flew much better, but still felt as though it was lumbering around.
I then changed the prop from 20x6 to 18x6. This made the Stampe feel much more sprightly, and improved the flying of loops and rolls. It still needs a lot of down elevator through the rolls, and inverted flight asks for all the down elevator I could give it, but at least it flies the maneouvres reasonably tidily.

Touch and goes are a delight - could do them all day!

There were a couple of minor problems, a landing wire connector broke and a cabane strut strain wire connector broke, but these are all part of the bedding in for big scale models. A tyre coming off the big expensive wheels is a nuisance too!

All in all a very good day out!

Steve.

[Nick Somerville]

Which wheels did you use, Steve?

[Jon H]

my cabane strut wires break all the time. I have more or less given up on them now as i got tired of fixing them. When i build another i will come up with a different solution i think.

Im still very surprised you find the model slow with the 20x6 as it looked plenty rapid in the videos. As i said before i spend most of my time trying to get mine to slow down as its more than happy to pick up speed and its not supposed to be fast.

I dont fly my model inverted as im not convinced its good for my structurally suspect wings. Im not worried they are going to break, its just they flex more than i would like and i dont want to take any chances. Again this is something else to fix on the MkII version when i get round to it.

[Martin McIntosh]

I too got a bit sick of replacing broken bracing wires so I have fitted short springs in line with each one. Try as I may the wings have not yet broken. I did, however, reinforce the joins with plenty of birch ply during the build.

[Steve Dunne]

Nick, the wheels are Sarik Hobbies DH82 quarter scale wheels - very nice scale wheels, I sanded off the DH logo and painted SV instead. I glued the hub halves together, but obviously did not do a very good job on gluing the tyres on! They are now glued on with thin cyano. Next time...

Martin, maybe I have that to come! The breaks were acually in the brass fittings at the end of the wires - one 2mm threaded rod quicklink fitting and one 3mm ring connector for the cabane strut stays. Weak points!?!.

Jon, I take your point on the flying speed, which is plenty enough for circuit flying. Once I start aerobatics, however, the aircraft seems to put the brakes on heavily - loops only just get over the top and rolls are "very interesting" once the plane is inverted. Far too much drag in biplanes!
The smaller prop seems to give enough power to overcome these problems, and then I only have to worry about my own inadequacies...

I am trying to get to the stage where I can replicate some of the displays that the full size Stampes give, but given that the model is quite porky (a bit like me!) I may have to compromise. Maybe I'll build the next one with a much lighter rear end.

Steve.

[Nick Somerville]

Have the same wheels on mine Steve. Lost a wheel on landing the other day, though not the tyre coming off. I had used parts of the stock 8swg main UC wire for the axle to crucifix connection. Trouble was that the axle after passing through the enlarged hole at the bottom of the H King oleos were nit long enough to pass all the way through the hubs. I extended the axle with tight fitting brass tube and then epoxied a pan headed 4m bolt into the tube to support the little bit of hollow tube and keep the wheel on. Anyway I have had two failures as it seems to be a woefully flawed solution. Just bought a length of 4mm piano wire and will make up the axle to crucifix as I should have done in the first place. Will glue tyres to hubs whilst about it.

I started with a 18x8 and now the engine has had enough running have changed to a 20x6. Rolls fine with a touch of down when inverted and a little opposite rudder in the final stage. Haven’t done consecutive rolls yet though as still very rusty on the sticks.

[Jon H]

Perhaps its your specific prop Steve? I have never tried one of those so dont know its performance. I know that some props like the master airscrews loose performance the more you rev them. Perhaps that one you have is all looks and no bite?

[Steve Dunne]

Yesterday I tried an 18x6 APC wide prop - 8100 revs and even better flying the than Graupner 18x6.

It would have been a wonderful day except for a sloppy landing. The approach was too high, I cut the revs too much and bounced it. Minor bend in the U/c - I blame very soft piano wire .

I flew both the new 1/4 SLEC/Precedent Stampe, and the 30+ year-old Svenson Stampe - same colours.

Steve.

[Jon H]

I flew mine yesterday too for the first time in..7 months? It was lovely to get it flying again and i got carried away on two of the flights staying up for over 20 minutes!

On the prop selection thing i still had my 20x6 hobby king special fitted and observed something that, presumably, i just ignored before as i flew it so often.

In a loop the model climbs up and obviously slows down. There came a point where it looked like it was just going to stop moving and fall out of the sky so i chickened out. Thinking it was odd as it used to loop fine, i tried again and found that once it gets down to a certain speed it just sits there, not getting any slower, and pulling round the loop as slow as you like. Over the next few flights i did countless loops and half cuban's, all with the same result. It just keeps going and its really nice to see it just floating there at the apex. Rolls needed almost no down elevator but were significantly barrelled, my half cuban 8's needed a little push on the 45 degree downline and a bit more once i started the roll out.

Stall turns are only good to the left due to engine torque

[martin collins 1]

Interesting that you flew both makes of 1/4 scale Stampe Steve, what were your impressions of the two compared? How do they come out weight wise with one another?

[Steve Dunne]

Thanks, Jon. It sounds like my experience on the 18x6.

I'll try it again next time out.

Steve.

[Steve Dunne]

Martin, The Svenson Stampe (foreground) is 1/5 scale, not 1/4. It flies on an OS91fs, with a 15x6 prop.

It was built over 30 years ago, so getting a little stiff and creaky (like me!).

The two Stampes are remarkably similar to fly, and caused no little confusion yesterday when I flew both
(not at the same time, we have to observe social distancing...).

The old Svenson 1/5 scale weighs 9lb 2oz, the SLEC 1/4 scale weighs 18lb 2oz.
I haven't yet decided which I prefer to fly, but the 1/5 Svenson is far easier to get up to and down from my loft workshop, up the ladder and through the small loft trapdoor....

Steve.