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Old Oct 17, 2008, 02:11 AM
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Lincoln, UK
Joined Jun 2005
614 Posts
Build Log
Lightened 39" Boddington Stampe SV4c

As promised, here are the details of the Stampe SV4c that I've been slowly piecing together over the past couple of months or so. It's based on the David Boddington plans that were published in the now sadly defunct Radio Control Scale Aircraft Quarterly of August 1986. It was designed around a .20 four stroke and to my eye appeared to be built like a bridge, even for a slimer model, so I've set to work lightening the design with virtually every component being re-engineered to be as strong yet light as possible. Also, DB's design was based on the Rothman's Stampe which had a faired over front cockpit, I've added an extra former in the turtle deck to open it up as there are far more two seaters than single seaters and therefore more colour scheme options. Having said that, I think I've already decided on how I'll finish the model but will defer from revealing this until nearer the end!

First a little background, I began this model as an experiment to see if the ideas I've had for an own design 32" Avia B534 are practical and light enough, so far everything has worked so I'm pretty happy with it. My interest in the Stampe began at an early age when I saw a fair number of them at regular airshows and fly-ins during the mid-eighties and was piqued again when I re-watched "High Road to China" which features some superb aerobatic sequences flown by Stampes. My late father also flew several full sized examples and always remarked on what a great handling aeroplane it was, much lighter in roll and better balanced than the Tiger Moths that he'd flown due to the more aerobatic wing section and by dint of the four ailerons as opposed to the two sported by the Tiger Moth and less heavy and cumbersome than the PT-17. In fact, he always said that the Stampe was equalled by the Bucker Jungmann but only bettered in handling and aerobatic performance by the contempory Bucker Jungmeister, a single seater and the more modern Pitts Special. If I recall correctly, its' only bugbears being a somewhat complicated inverted fuel system and a wooden tie-bar in the lower wing centre section that required regular replacement.

Anyway, these are not issues with the model version!

I began by laying out a fuselage side using 1/8th" sq balsa strip then built the second side over the first, next came the tedious task of making the lightened formers. Instead of the 1/8" ply dictated on the plan for the main load-bearing formers, I built them with 1/8" balsa with 1/8" sq spruce let in across the strut anchoring points, the whole then being faced on both sides with 0.4mm ply and then judiciously pared down with lightening holes. The load bearing formers right back to the rear of the lower wing saddle are constructed thus. In other places where the plan suggested 1/8" balsa formers, I constructed them with 1/16" balsa with 1/8th" x 1/16" strips being glued to the rear to carry the loads and lightening holes let in more for looks than anything else! The fuselage sides were then joined and the top stringers added, the plan specifies 3/32" x 3/16" spruce for these, I went with 1/16" x 3/16" balsa which seems more than adequately strong to my eye and about a fifth of the weight. Up to now I have bent the cabanes from 16swg piano wire, these are taped and propped into position currently to ensure that the top wing incidence is correct and I have also begun to make the 0.4mm ply decking pieces. See photos below. Please don't hold your collective breath on this one, I'm a slow but steady builder and I haven't a huge amount of time at my disposal right now but so far I'm pleased with the results and the current weight (as pictured in the final photo) of appx. 73 grams (2.6oz in real money). I tested the power train; an Ebay el cheapo brushless motor turning a 10x5 electric prop, 30A speed controller and an 1800mAh 3 cell Lipo on a pod fitted to a Ripmax Coyote slope soarer that belongs to a friend, it flew quite well but I don't think it had quite enough grunt to overcome the extra drag that's built into the Stampe (I want this model to be realistically aerobatic) so have ordered a more powerful motor to fit to the pod and test. In the meantime I'll keep plodding on with the build!
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Old Oct 17, 2008, 08:43 AM
Two left thumbs
Muncie, IN
Joined Sep 2006
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Looking good, Pete!

As far as the full scale one's improved performance over the Tiger Moth, I've read that that was exactly why Jean Stampe had it built!

There are only two Stampes here in the USA that I know of, and one of them lies wrecked at Old Rhinebeck Aerodrome in New York. The other one is local, and done in French Aeronavale markings.

Addition: I have the old RCMW 59" span SV4 plans that I have considered reducing and lightening. Too bad I've sooooo many things going already, or I'd join you in a Stampe-a-thon! :-)

Geoff
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Old Oct 18, 2008, 06:00 AM
North East England
Joined Feb 2004
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As a big fan of Boddo's designs I'm glad to see yet another of his plans 'electrified'. He certainly designed them 'robustly' (to put it mildly)

I converted his 68" 'Emma' model to 30" electric - thread is on here somewhere - using similar construction to what you're doing now; 1/8" frames, 3"32" front, reduced wire sizes, etc and it's a good flyer with a small outrunner. I think these old glow plans from people like DB, Gordon Whitehead, Clive Smalley, etc are perfect for electric conversion.

I'll be following your thread for construction methods as I have a Bucker Jungmann plan which I'd like to modify for electric one day - not too dissimilar.

Steve
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Old Oct 18, 2008, 06:17 AM
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Lincoln, UK
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Thanks for your kind words and encouragement, Steve and Geoff, I'll be busy this weekend sadly but hope to get some more of the Stampe built and posted on Monday before work (I work on dreaded permanent nightshifts, 21:00 to 07:00 all week). I also forgot to thank FLB in my first post for sending me some great drawings of the Stampe SV4c so I could get the front cockpit aperture just right, a belated thanks, Frederic! More progress to follow shortly, watch this space...

Pete
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Old Oct 18, 2008, 08:01 AM
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Aylesbury, Buckinghamshire, Great Britain (UK)
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Looking nice Pete, I recokon you could have dispensed with the rear lower formers as well, simple horizontal stick framing would have been sufficient I'm sure.

Mike
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Old Oct 18, 2008, 09:50 AM
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Lincoln, UK
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Thanks Mike,

You're completely right about the full formers vs sticks arrangement however, the balsa I used for those particular formers was very light and soft (actually, a bit of a pain to notch for the stringers) and using formers makes the build that little bit easier to get square and true (I was feeling lazy)!

Pete
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Old Oct 22, 2008, 02:55 PM
I eat glue
Canada, NS, Yarmouth
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Show me a fuselage built square and true, and I'll show you one that I didn't build!
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Old Oct 22, 2008, 05:06 PM
North East England
Joined Feb 2004
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..plus I find if I build a straight fuselage, there's nothing then to counterract the warps in the wings

Funnily enough, the worst model I've ever seen - a glow-powered 'Yamamoto' trainer, with EVERY surface misaligned or warped - flew absolutely beautifully. Obviously every fault cancelled each other out!

Steve
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Old Oct 22, 2008, 08:29 PM
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Lincoln, UK
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Strange you should say that, as a child I built a Veron Tru-Flite rubber powered Hawker Hurricane that was full of warps and twists but it flew straight off the board! I've been trying to solder up the cabanes on the Stampe this evening but am not happy with the results, I feel a better jig is in order, progress to follow!
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Old Oct 23, 2008, 02:19 AM
Light and floaty does it
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Cambridge, Great Britain (UK)
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I really like this very much, and have the same plan in the "one day" pile with exactly the same idea, using a geared 480 or similar. I suggest that you might find 9x6 or 9x7 a better prop match, but that's a fair way up the road.
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Old Oct 24, 2008, 03:25 AM
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Lincoln, UK
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Well, not a huge leap to report, I'm afraid, just a bit of bending and soldering done, the cabanes are ready to fit now. I've not got as much done this week as I'd have liked but it's a bit further down the road. I'm no fan of bending and fitting wire parts and went through a good few feet of 18 swg wire getting these bracing wires right. My soldering iron packed up on Monday and I had to wait until Wednesday to borrow one from a friend, I think I'll have to chase the moths out of my wallet and invest in a new one of my own... I'm off to buy a new car today though so money'll be tight for the next few months paying that off!
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Old Oct 24, 2008, 05:51 AM
North East England
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I only wish I could solder, Pete - I probably don't have the right size iron, as I can solder connectors no problem. I tend to just roughen up and bind my struts with thread soaked in glue - luckily I never build anything too big.

Good luck with the hunt for a new car - make sure the space inside is just slightly larger than your biggest model

Steve
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Old Oct 24, 2008, 11:26 AM
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Lincoln, UK
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Thanks Steve,

I used a 20W Black and Decker Iron for this job, it wasn't as good as my old iron which could be set to any temperature as it only had two temperature settings, too cold or too hot! I bound the wire with thin copper flex stripped from a broken lamp and heated the wire from the back before applying the solder from the front, allowing it to wick into the joint. Soldering used to be a major part of my old job as an instrumentation technician so I'm pretty comfortable with it. In some ways I wish I was still doing the job as I used to have all the kit for silver soldering.

I've bought a Ford Mondeo hatchback, plenty big enough for anything I fly now!
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Old Nov 06, 2008, 06:18 AM
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Lincoln, UK
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A tiny bit more progress

I lost most of last weekend due to family obligations but I've managed to make a little more progress. I've built and fitted the battery box and begun to make the mould for the cowling. The first attempt went all wrong when I tried to use my hot wire cutter to do the job but when I brought out the trusty bread knife and a large blue foam sanding block things went a whole lot better. I know that I'm making a long job out of this one but to quote the Stampe-centred film, "High Road to China"; "The oxen is slow, but the Earth is patient"! I bought another motor to test on the Coyote but the friend who owns it will be working in Equatorial Guinea for the next month, oh well, more time for building!
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Old Nov 06, 2008, 08:22 AM
Two left thumbs
Muncie, IN
Joined Sep 2006
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That's a very smooth cut for the cowl plug, Pete. Nice work!

Are you using light ply for the forward formers?

Geoff
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