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Flying on 14 hp

Posted By:
Matthew Long
Homebuilder or Craftsman
122
Posts
12
#1 Posted: 7/13/2010 07:56:08

Lately I have become enamored of the idea of a simple little aircraft designed around the 14hp Radne Raket 120 Aero RD-ES engine.  This engine is quite popular with paramators, toecutter powered hang gliders and nanolight trikes.  See the manufacturers web page or download a brochure with performance curves and dimensions (2.3MB .pdf file) for more info and specs.  The good news is that the engine complete with starter, redrive and basic exhaust is available from the factory for less than $1,100.  Even with a prop, battery and optional tuned exhaust, the total powerplant runs less that $2,000.

I would like to adapt this engine to an existing airframe or design a custom airframe to suit.  I know that the latter is an ambitious undertaking, but I have been around light aviation for many years and have a good general idea of what that would entail.  I am not in any hurry and I'd like to keep the cost down, ideally shooting for around $5,000 in materials and equipment, as an exercise in low-cost flying.

I already have some clear ideas on how I might tackle this, which I will share later, but first I'd like to hear ideas and suggestions from the members here.  A few basic criteria:

1.  Payload (pilot & fuel) of 250 lb

2.  Performance within European microlight limits (40 mph stall, 660 lb gross weight) and preferably closer to U.S. Part 103 ultralight limits (27 mph stall, 254 empty weight).  Full compliance with Part 103 is not required.

3.  Fixed wing design (not Rogallo wing trike or powered hang glider)

4.  Two- or three-axis controls

5.  Not foot-launched and with some crash protection for the pilot

6.  Suitable for building in a small workshop (single car garage or less)

7.  Easily assembled/disassembled (less that 30 minutes) for transportation on or in a small trailer 

8.  As the Raket is already set up as fan-cooled pusher, the engine should remain in that orientation

I have deliberately not specified any configuration, construction method, etc. as I want this to be a brainstorming session.  Like I said, I have some ideas that I will share later, but I want to hear yours first.  Word concepts are great, sketches are better and pics and references of actual aircraft to use as inspiration are best.

What do you say?



******* Matthew Long www.cluttonfred.info
Dick Anderson
Homebuilder or Craftsman
74
Posts
14
#2 Posted: 7/14/2010 20:11:12

Hi, Matthew.

       The Mitchell Wing B-10 would easily meet your criteria. It originally was powered by a 10 hp pusher engine, although later the factory used a 20 hp Zenoah. I put a 28 hp Rotax 277 on mine and if anything was overpowered- throttle changes caused large up or down pitch movements. Many different engines, even a jet, have been successfully used. Although open, the pilot cage is very strong- later versions had a fiberglass semi-enclosed fairing. After the tip rudders are removed, the outer sections of the wing fold over the inner part- takes less than 10 minutes and can then be hauled sideways on a trailer. A friend of mine even built a mount on top of his car for his wing with a carrier on the rear for the cage. The wing is made of wood, then fabric covered. The pilot cage was bolted and pop-riveted. The last version- the A-10- had an aluminum wing, but was very easily dented. I flew my 243 lb. B-10 300 miles each way to Oshkosh with my camping gear- although I was a lot lighter back then. It is fairly easy to build, fun to fly, attracts a lot of attention- all-in-all- very cool.



Dick Anderson
Matthew Long
Homebuilder or Craftsman
122
Posts
12
#3 Posted: 7/17/2010 09:59:22

Thanks, Dick, for the suggestion.  I have seen a Mitchell wing up close and seen it fly and was very impressed...the one I saw had a Rotax 277 if I remember correctly.



******* Matthew Long www.cluttonfred.info
Matthew Long
Homebuilder or Craftsman
122
Posts
12
#4 Posted: 7/17/2010 10:02:43

I had hoped to prompt a livelier discussion and get the creative juices flowing.  Here or some possible inspirations I have in mind for an inexpensive aircraft with Radne Raket power...

Francois Butterfly (9 HP)
http://www.flyingflea.org/docs/butterfly.html

Croses Pouplume (8 HP) (this one's in French)
http://www.croses.fr/articles.php?lng=fr&pg=62

Debreyer Pelican (9 HP in the original prototype, the more angular model in the lower right photo)
http://www.nurflugel.com/Nurflugel/Fauvel/e_pelican.htm

Sandlin PIG (unpowered, but easily adapted to a paramotor engine)
http://m-sandlin.info/pig/pig.htm

Thoughts?




******* Matthew Long www.cluttonfred.info
Craig Christopher
IAC Member
5
Posts
1
#5 Posted: 7/19/2010 12:47:34

Hi Matthew, I have always had an interest in the Lazair and the very first Kolb design. Both little twins but total HP of 20 or less, both available with conventional three axis. Good luck with your project. Craig



Howard Handelman
Homebuilder or Craftsman
17
Posts
1
#6 Posted: 7/22/2010 17:50:09

I can't tell for sure, but if this engine is still available it would serve you well. I had one in a Moni (ancestor of the Sonex).

http://www.italmotion.com/1071.html

At 6000 rpm with a 30" prop you won't need gear reduction.



Matthew Long
Homebuilder or Craftsman
122
Posts
12
#7 Posted: 7/23/2010 02:28:35

Thanks, Howard, but as far as I can tell that site is the former distributor of the KFM engines and still has parts but not complete engines.



******* Matthew Long www.cluttonfred.info
Kenneth Anderson
Young Eagles Pilot or VolunteerHomebuilder or Craftsman
4
Posts
0
#8 Posted: 8/4/2010 08:53:27

Matthew,

14 HP is plenty of power in the low and slow world.  After all, the Wrights had only around 12 (but launched by a catapult and didn't have sprightly performance...). 

Have you looked at the original Quickie?  You can visit the Quickheads page www.quickheads.com

It was originally powered by an 18 HP Onan engine (although I've heard that most people are installing a Rotax)

I've often wondered how it would do with one of the new B&S Vanguard V-Twin enignes?...  But I digress....

I grew up in Tulsa, and during the height of the ultralight movement there was a pusher ultralight called the XTC that some locals built.  I think it is in the Tulsa Air and Space Museum www.tulsaairandspacemuseum.com

Here's a link to the exhibits page:

http://www.tulsaairandspacemuseum.com/exhibits.php?nav=exhibits

Scroll down to the XTC

Here's the write-up from there:

One of the world’s first amphibious ultralights, the XTC (Ecstasy) was manufactured in Jenks, Oklahoma. It was designed to be disassembled and towed on a standard boat trailer to your favorite lake allowing you to fly high above the water and look down on the lake-locked boaters.

I remember it flew at a fly-in at the now closed Tulsa Downtown Airport.  I was a kid then and really thought it was neat.  I don't know what engine it used, but it was pretty light if I remember correctly.  You might be able to get more info by contacting the museum and see if they can put you in touch with the builders.

I like the idea of a low power, efficient commuter, and have been looking at a Quickie or a BD-17 or???

Good luck on your project

Ken



Files Attachment(s):
xtc.jpg (6318 bytes)
Ried Jacobsen
194
Posts
26
#9 Posted: 8/27/2010 08:30:02

I recently re-read a 1982 article on the Moni, and the KFM-108? engine was 22 HP.  I don't know if 14 HP could get it off the ground.

The Moni would be a source for design ideas though.  I was very tempted at the time to buy a kit, but did not pull the trigger when I had the chance.  It used some assemble methods that were ahead of its time as I recall, and had some bad problems with builders not getting the assembly correct.

A varient miight work out well.