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Oct 27, 2016, 09:21 AM
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Build Log

1/4 scale Sparmann P-1


THREAD MOVED FROM THE SCALE FUEL PLANES FORUM

It's been a while since I started a build thread on RCG, so I'm back for more abuse (or help).

A little background first. The majority of my modeling experience has been centered around sailplanes. I started building gliders and sailplanes back when I was a kid because I thought they would be easier to teach myself. That started 30 years of flying nothing but sailplanes.

Until about 5 years ago.....

I started building small electric powered scale airplanes and ended up building a number of Peter Rake and Pat Trittle designs. Easy to build, easy to fly, and perfect from flying off of the street in front of my house (each house in my development has 1-2 acres of property so lots of room). That really got my juices flowing and got me more and more focused on Scale subjects. My next build was a scale sailplane - a Cherokee to be exact - but the scale powered planes had their hooks firmly in me.

Then I also started hanging around with my friend ARUP, and his scale focus really started rubbing off on me and we made a deal to build a couple of scale planes for a future event, but more on that much later.

So, on to why this build log and my subject. Why the log? Well, primarily to keep me motivated and focused and hopefully not give up half way through the project. This will be my most ambitious project to-date, so I'll need the motivation and encouragement and advice. I'm a Partner in a large management consulting firm, I have 2 kids, and I'm into my fitness, so building model airplanes is a passion but is still a hobby so please bear with me if I'm not posting new build updates once a day!

Next post will be more about the subject.....
Last edited by dion9146; May 12, 2017 at 06:04 AM.
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Oct 27, 2016, 09:30 AM
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So why the Sparmann?

Well, I've always loved the look of Golden Age airplanes, and I also like military subjects, so I was on the lookout for something in that range. I spotted a couple of pics of the Sparmann, and I was hooked. I started buying all of the old magazine articles, plans, and subject material that I could find. I also started planning this build about a year ago, so I've thought it through long enough. Time to start cutting wood.

The Sparmann P-1 was a Swedish military trainer developed during the mid-30's. I won't go into all of the details, but not many examples were produced as Edward Sparmann did not get the contract from the Swedish military that he was chasing. However, the pilots who did get to fly the plane had very good things to say about it with good flying qualities. So again, I though it would be a good subject to model.

http://www.avrosys.nu/aircraft/Misc/461P1.htm
Oct 27, 2016, 09:42 AM
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I've picked up a number of sets of plans ranging from Peanut scale rubber plans to 1/3rd scale fuel powered. I settled on 1/4 scale for my topic because I thought it would present a good size / detail compromise, and it also fits my workshop and storage ability much easier. This is a small airplane to begin with, so at 1/4 scale the span is still only 2 meters or about 72".

The plans were created by Eugene Martin and were drawn in the late 70's, but have very good detail and the plans themselves are drawn nicely. There is still a fair amount of interpretation that needs to go into the build, but I'm fine with that. I rarely build anything exactly as designed anyway. The finished product built by Eugene can also be seen in the June 1980 issue of Scale RC Modeler, Vol 6, No. 3.

My first challenges to tackle were the hard parts - the cowl and the wheel pants. The great thing about the Sparmann is the fact that it used the de Havilland Gypsy Major engine and what appears to be the same cowl as a Tiger Moth. So I went searching for a Tiger Moth cowl, and sure enough Hanger 9 makes a very nice 1/4 scale version. So that is a big part of the build that I didn't need to scratch.

The wheel pants are a different story.
Last edited by dion9146; Nov 14, 2016 at 08:48 AM.
Oct 27, 2016, 09:50 AM
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First disclaimer - I've worked plenty with fiberglass including making several race car parts (another hobby from another time), and have made a number of lost foam pieces for various gliders. But, I've never made a mold designed to recreate multiple versions of a part. So this is my first attempt at making a plug and mold.

I started with blocks of foam, patterns made from the plans, and a knife and sandpaper. BTW - foam gets everywhere when it is being sanded!

After I got it to shape, I coated it with 2 layers of .75 oz fiberglass and resin. A little more sanding and some filling with bondo, and I got a shape I was really happy with. Then I primered it and painted it with auto body enamel paint. I've since coated it with 5 coats of carnuba wax. Next up is the parting board and making the mold halves.
Oct 27, 2016, 12:11 PM
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In the meantime....

I also started on the stab and elevator. I just needed to start cutting wood I guess, so that the rear is getting started first. Both the stab and elevator are built around 3/32" sheet balsa with ribs on the top and bottom. The 'spars' are hard balsa. Overall, the stab and elevator turned out very stiff. I've contemplated cutting lightening holes in the sheet balsa because I think it's overkill, but I also don't want to sacrifice any stiffness. Thoughts?

Since the control horn is hidden inside the fuselage, I made it out of brass sheet and square rod. This wasnt clearly shown on the plans, so this is my first 'build it my way' modification. It obviously serves as the connector between the two elevator horns. It turned out beautifully and has a nice smooth throw on the elevator.
Oct 28, 2016, 11:37 AM
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Lookin' good .

Mark
Oct 29, 2016, 07:32 PM
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Thanks Mark.

Truth be told, I started this build thread while sitting on a beach in Florida. I got back this afternoon, and have a few more pics to upload.

I was able to get most of the rudder done before leaving for vacation. It's built the same way as the stab/elevator - a sandwich construction style. This piece still needs the bottom fill and a rough shaving and sanding, but you get the idea. I also decided to steam bend the 1/8" x 1/4" balsa trailing edge pieces (4 in total). You can see the foam mold that I used to hold the bend to shape.
Oct 29, 2016, 07:40 PM
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Also, you may wonder why I'm posting this build thread in the Scale Fuel forum when I've been building scale electric planes. As a matter of fact, I haven't flipped a prop on a fuel bird since my Sig Seniorita in 1988.

But I felt that this one needed the sound that only a 4 stroke can make. I thought about putting in a sound module and making it electric, but really wanted to take the opportunity to re-learn the art of fuel again. Plus ARUP talked me into it....so this lump is going on the front under that beautiful cowl.

CHANGE OF PLANS - GOING BACK TO E-POWER FOR THIS ONE!
Last edited by dion9146; May 12, 2017 at 05:55 AM.
Oct 29, 2016, 07:50 PM
boat butcher
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Quote:
Originally Posted by dion9146
Also, you may wonder why I'm posting this build thread in the Scale Fuel forum when I've been building scale electric planes. As a matter of fact, I haven't flipped a prop on a fuel bird since my Sig Seniorita in 1988.

But I felt that this one needed the sound that only a 4 stroke can make. I thought about putting in a sound module and making it electric, but really wanted to take the opportunity to re-learn the art of fuel again. Plus ARUP talked me into it....so this lump is going on the front under that beautiful cowl.


Mark
Oct 30, 2016, 11:36 AM
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Quote:
Originally Posted by dion9146
The great thing about the Sparmann is the fact that it used the de Havilland Gypsy Major engine and what appears to be the same cowl as a Tiger Moth. So I went searching for a Tiger Moth cowl, and sure enough Hanger 9 makes a very nice 1/4 scale version. So that is a big part of the build that I didn't need to scratch.
Might take a look at this: https://www.rcgroups.com/forums/show....php?t=2768068 May be the same size, never hurts to have spares....
Oct 30, 2016, 01:27 PM
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The Sparmann has been on my "to do" list for more years than I care to think about. It is a lovely little airplane that should translate nicely into model form. At my current rate chances are I won't live long enough to get one built for myself so I will enjoy building vicariously through you dion! Carry on!

PS - Should you care to lay up an extra set of wheel spats I would be interested in purchasing them.
Oct 30, 2016, 04:07 PM
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Quote:
Originally Posted by ahrma_581
Might take a look at this: https://www.rcgroups.com/forums/show....php?t=2768068 May be the same size, never hurts to have spares....
Thanks!
Oct 30, 2016, 04:09 PM
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Thanks Chad. I'm also vicariously living through other's builds, but that's the great thing about these forums isn't it!? Thanks for watching, and I'll keep you in mind for an extra set of wheel pants. I'm sure I'll be making a few sets.
Nov 06, 2016, 05:43 PM
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I managed to get some building (and yard work) done this weekend. I've just about got the fin and rudder finished, just need to get it hinged. Most of the time was spent making the base of the fin as it required multiple compound cuts to get it to fit the Stab profile, but it turned out pretty good.
Nov 06, 2016, 06:13 PM
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Beauty!


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