Funbuild 5 - 64" Bugatti 100P - RC Groups
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Jan 10, 2012, 07:36 AM
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aerophilia's Avatar

Funbuild 5 - 64" Bugatti 100P

The stars have aligned and I have decided to enter funbuild 5!

Air Venture Museum in Oshkosh has a great history of this plane if you are interested ( Short story, plane was built in the late 1930's, not completed, war broke out, plane was hidden in a barn, found 30 years later, changed hands a number of times before it ended up at the airventure museum, who completed a restoration.

It is a work of art.

I first saw drawings of the plane around 5 years ago when I first got interested in RC planes. and started looking for plans straight away!

While I found plans, I never got around to doing anything about it. That all changed sometime last year when I found a 64" short kit being laser cut in Oz. What got me even more excited was a Himax CR5025 contra rotating motor. The spinner that comes with this motor is so close to matching the front of this kit it's not funny. I couldn't believe my luck. The kit call for a 3" spinner, and the one supplied with the motor is just under 2 and 7/8ths. Close enough for me!

I'm really looking forward to building this plane.

Short kit
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Jan 10, 2012, 07:54 AM
Registered User
Wow interesting aeroplane, looking forward to following this one, good luck with the build

Jan 10, 2012, 10:38 AM
Flying electric since 1986
Mark Wolf's Avatar
I look forward to following your progress. I've seen Keith Shaw fly his scratch built Bugatti many times and it never fails to impress.
Jan 10, 2012, 05:14 PM
It flew once before...
jofrost's Avatar
Very cool subject and Welcome to Funbuild 5

Jan 10, 2012, 06:45 PM
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aerophilia's Avatar
Originally Posted by heli_madken
Wow interesting aeroplane, looking forward to following this one, good luck with the build

Thanks Ken. It is a fascinating plane, and for more than its looks!

Originally Posted by Mark Wolf
I look forward to following your progress. I've seen Keith Shaw fly his scratch built Bugatti many times and it never fails to impress.
Thanks Mark, I have seen videos of Keiths Bugatti. It sounded incredible on that gearbox setup. The video I have found was from 2005. I'd really like to know what his all up weight was, as I reckon the size is similar to mine.

Originally Posted by jofrost
Very cool subject and Welcome to Funbuild 5

Thanks John! First step is to get the plans printed. I'll try and do that today.....
Jan 11, 2012, 06:54 AM
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aerophilia's Avatar
I printed the plans today. The fuse looks longer and the wings look shorter that I thought!

I was concerned that my weight was going to be way over 9 pounds given the size of the himax motor. It weighs 29 ounces with props and spinner alone!! The original builder had a 1.20 Magnum that weighed nearly 33 ounces with muffler. Which is ok, but I have to add a decent 6S pack in there somewhere!!

Anyway, I worked backwards from his AUW, removing engine, tank, etc, then adding my motor, esc's, BEC, batteries, retracts and I come out at 500 grams heavier. As a guess! That's a pound. If I can keep it under 10 pounds I will be very happy.

After looking at the plans, I have 2 immediate issues. The original wasn't designed for retracts. And it wasn't designed to take a 6S lipo. The space for the fuel tank is way too far forward in the fuse for the pack. And the wings plug into the fuse, so there's no access to the fuse cavity really. I am thinking a battery box somewhere with hatch built into the formers in the appropriate location for the COG.
Jan 11, 2012, 03:50 PM
Warbird crazy!
new2rc's Avatar
Super subject.
I'll be following this.

I was looking to pick up this short kit at some point:

Best of luck on your build!

Jan 11, 2012, 05:29 PM
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Ken Myers's Avatar
There is a good article in the December 2004 issue of the Ampeer written by Keith Shaw about his model. I've looked through it several times and didn't come up with a flying weight.

The model has a 65" span and is 60" long with retracts and contra-rotating props.

found more on the original NiCad power system version here

You can find more on the Bugatti by searching the Complete Ampeer Index at
Last edited by Ken Myers; Jan 13, 2012 at 09:23 AM. Reason: Correct URL
Jan 12, 2012, 05:02 PM
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aerophilia's Avatar
Hi John, that looks like a good kit. Designed for electric, which should save you some grief!! Looks like a nice kit. The cockpit looks great.

Thanks for the links Ken. I had not come across those pages before. I'm certain I will learn something from Keiths notes. His model certainly is beautiful. I think I read his model was around 10 pounds from a page where I found a video. I will try and find the link later today.

I'm going to post some pics later today and ask for some advice on changing the wing to accept the retracts.
Jan 12, 2012, 05:32 PM
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Ken Myers's Avatar
Here was the second drive that Keith put together and did not use, but flew on his test bed.

Look for Counter-Rotating Gearbox Flies!

I don't think it weighs 10 pounds. I guess it would just be easiest to pick up the phone and give him a call. I'll do that later this evening.
Jan 12, 2012, 07:21 PM
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aerophilia's Avatar
Righto, not sure where I got 10 pounds from! Here's the link to the video
I was sure I had read it on that page somewhere!

If you get the chance to speak to Keith, that would be great. I'll have to search those pages a bit more when I have some time.
Jan 12, 2012, 08:05 PM
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Ken Myers's Avatar
I just got off the phone with Keith. We a bunch of catching up to do.

He said 8 lb., maybe 8.25 lb. Since it evolved over such a long period of time, the original weight is 'lost' to his memory and my not writing it down. Might have been 10 lb. with NiCads and the original AF brushed 40 with his machined double drive gearbox.

Best of luck with your project.

Jan 12, 2012, 09:14 PM
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aerophilia's Avatar
Thanks so much Ken. I really appreciate your time and input.

The more I look at my motor the more concerned I am that it is just going to be too big. Problem is, I can't find one just the right size. Himax make a range of contra rotating motors, but the next one down is rated to 800 watts and 126 ounces of static thrust. Mine is 2000 watts and 326 ounces of static thrust. I wish they made something in between these two, that would be perfect!! The difference in the weight of these motors is around one pound.

So, if anyone knows of a Contra setup that weighs in around the 15-18 ounce range please let me know!!
Last edited by aerophilia; Jan 12, 2012 at 09:24 PM.
Jan 13, 2012, 01:41 PM
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Ken Myers's Avatar
I made Keith a bit curious about his Bugatti's weight. Here's an email I received from him this afternoon.

"Hi Ken

I weighed the Bugatti last night, right at 8.5#. It's 1/5th scale, so 65" span. With the nicads and single Astro 40 drive it weighed a bit over 10#. I went to ezone to look at his project. My biggest concern will be the ability to get it to balance with the heavy HiMax CR system. With the Astro40 drive (and the 20 cell nicad pack pushed as far back as possible), I had to put 5 or 6 ounces of lead into the rearmost "stinger" fairing to get it even close to balance. It was still very nose-heavy, and unless power was applied ever so slowly it would go right over on its nose.

Actually the switch to the twin Astro 05bl setup was mostly to reduce nose weight. I was able to dig the lead out of the fairing, and use a 3s3p lipo pack get it to balance back to where I had at least some ability to prevent nose-overs. I would recommend putting a nose skid on his like I did to protect the drive train. When I designed the plane I had to use every geometric trick I knew to get the wheels as far forward as possible and still retract into the wing. The scale position is WAY too far back even for pavement. I fly the plane with the CG as far back as I dare to help the nose-over situation, which makes the plane quite lively in pitch. Right after takeoff I click the dual rate elevator switch to a 50% rate, THEN retract the gear. Initially I had quite a jump at takeoff until I could get it on low rate, but have finally got used to it so things go more smoothly now.

A side benefit of the twin motor drive was the ability to match the prop RPMs for best loading. This was done with a homemade telemetry system (it was long before Eagle Tree!) Initial calculations with the single motor drive indicated that the rear prop should have about 25-30% more pitch. However when the twin motor system was monitored it showed that the front motor was virtually unloaded in flight. I couldn't change the props, as I had designed the drive and spinners around them, so I was left with changing the gearbox ratio on the front drive. When all was said and done I got the best performance and current balance when the pitch speed of the rear prop was only about 5% more that the front prop. So equal pitched props would have been a better choice, or maybe 1" more pitch on the rear prop. Goes against textbook wisdom, but hey, I'm an experimental physicist, so I trust real world data over calculations/simulations.

Hope this helps. Too bad he lives so far away, it would be great to see them both in the air together!


BTW, I looked for the Wolf's Call, but it still eludes me..."

The little note about the Wolf's Call, was what the first edition, March 1988, of the Ampeer was called. Wolf was for West Oakland 'Lectric Flyers, the proposed name of what was to become the Electric Flyers Only (EFO) of southeastern Michigan.
Jan 13, 2012, 11:15 PM
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aerophilia's Avatar
Thanks for posting that Ken, and thanks to Keith for taking the time to weigh your model and share some of your knowledge with your model.

I'm not too concerned with getting the CG right. I'm planning on putting the batteries as far back as I need to to get the CG right. This is going to be heavy enough without adding lead! There is plenty of room in between the spine and formers for a couple of batteries to fit.I'm thinking 2x 3S 3300 packs in series. One either side of the fuse vertically so that I can access them through hatches in the top of the fuse.

I'll have to do some research on the nose skid. A great friend of mine said to do away with the retract idea, hand launch it, and carry lots of props! Adding the retracts is going to take a bit of work, but where there is a will........

It's funny with the props, I have read so much about the rear prop needing more pitch than the front. The reason I purchased the Himax motor was that it comes with the spinner and 2x 15x10 props. So I'll test those out first and see how they go. I figured they came to the same conclusion as Keith!

Keith, if you are reading this, be greatful we live on the opposite side of the planet while I'm building this....I'd be on your doorstep every afternoon asking for help!! It would be pretty cool to see them both flying around together though.

Thanks again for all your time and input guys.

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