The One Design was created to make a high performance acrobatic aircraft on a low budget. It was designed to get the most out of a O-360 Lycoming motor. The Wiki page has a brief overview of the aircraft at: https://en.wikipedia.org/wiki/Rihn_DR-107_One_Design

YouTube has a bunch of videos on this aircraft, here are a few

This video has a real good 3D cad overview of the structure

You can get the Plans and Materials for the One Design from Aircraft Spruce: https://www.aircraftspruce.com/catalog/kitspages/onedesign.php

The EAA has a few dozen articles that cover this aircraft and they can be found here: https://www.eaa.org/eaa/aircraft-building/kits-and-plans/r—s/rihn-dr-107-and-dr-109

Finished ready to fly examples can be found on Barnstormers for $50K+: https://www.barnstormers.com/category-15896-Aerobatic–One-Design.html

For those looking for an RC version Outerzone has a 72″ span plans from RCM: https://outerzone.co.uk/plan_details.asp?ID=10576

Back in the early 2000’s I got to do Acrobatic Training in a Super Decathlon at KPRC Prescott AZ. This aircraft is one of the best entries into Acrobatics & Tail Wheels, gaining more confidence and capability as a pilot.

The Decathlon started Production in 1972 and is a derivative of a Citabria.

Prices range from 50 to over 200K depending on year, condition etc.

https://en.wikipedia.org/wiki/American_Champion_Decathlon

There are some RC Options available. Great Planes made a 64″ kit that you may be able to find on eBay or a large hobby shop like Graves in Orlando FL. Outerzone has the plans for it at:

https://outerzone.co.uk/plan_details.asp?ID=10203

EAA w/ Sport Aviation info: https://www.eaa.org/eaa/aircraft-building/kits-and-plans/d—g/gp-4

Wiki: https://en.wikipedia.org/wiki/Osprey_GP-4

Company: https://www.ospreyaircraft.com/

Here are some photos I took at Airventure 03 & 06

From what I have found there are no available Plans, Kits or Downloads for the GP-4, however with modern tech like 3d scanning iPhones, Powerful Cad Software and 3D printers it would not be too difficult to create a RC version of this impressive Aircraft.

I recently got to see a very interesting documentary on moving the H4 Spruce Goose from California to Oregon on YouTube. I got to see this unique aircraft at the Evergreen Aviation Museum just outside of Portland Oregon, on a few days off from a company trip in 2014. https://www.evergreenmuseum.org/ https://en.wikipedia.org/wiki/Evergreen_Aviation_%26_Space_Museum. If your into historic aircraft this Museum is one of the best in the country with the Smithsonian NASM in Washington DC, USAF Museum in Dayton Ohio & the EAA Museum in Oshkosh Wisconsin as peers and is well with the drive alone from any of the surrounding states.

When you see it in person its difficult to get the whole aircraft in one shot with out a wide angle lense

Much of the structure is actually laminated wood with grain direction for optimized strength and is a pre curser to modern composite aircraft structures. They have a few displays of some details of the construction methods along with a scale model of the aircraft under construction.

An ominous shot from a rear quarter view with a ME-262 and a FW-190 showing what this war bird would have been up against if it would have been operational in the war.

My personal thoughts on the aircraft with the context of seeing the 2004 movie the aviator and a few documentaries on Hughes is its a mix of a technology path finder paving the way to large aircraft structures and systems while being a tragedy for Hughes personal aviation career. He was never the same after this project.

Aircraft like his racer and XF-11 had fairly quick development times however the H4 flew 2 years after the end of the war it was supposed to support. Because the project was under a government contract with government funding it Aircraft like the Grumman albatross and Martin Mars Evolutionary and nature compared to the revolutionary H4. However this difference was not taken into account for the oversight, visibility and pressure.

This aircraft serves as a cautionary tale for any company or individual taking on a “huge leap task” with out proper technology development and stepping stones setup at the beginning. Crawl, walk, run marathon or sprint. This is hubris that has effected my self and have seen first hand at companies I’ve worked for.