Freedom Master AirSharkII

Homebuilt Aircraft & Kit Plane Forum

Help Support Homebuilt Aircraft & Kit Plane Forum:


Sep 18, 2003
Ft Lauderdale, FL
I just came across your posting and I am indeed interested. I have an Adventurer amphibian
Adventurer-Drawing Edit b.jpg

which I am trying to revise/redesign. So, I am running into the same considerations. I was wondering what problems you are trying to overcome. With the Adventurer, My primary concern is the lack of an engineered design. Before I ever allow it to fly, I will have evaluated and redesigned, if necessary, all the critical elements. My most bothersome concern is the high thrust line and a lack of dynamic balance due to an undersized horizontal tail plane and elevator.
Dick in S Florida


Well-Known Member
Aug 2, 2006
Thrust Line

I feel like i am on the same page as you with regards to high centrelines and short tail moments! I am considering sweeping the wing backwards to add some stability. but that can introduce additional problems. I really need to test a large model at this point and make it do strange things!

I am not the best guy to help you with thrust line issues. I will be seeking out the help of more qualified people than myself when determining the thrust line properly. I have also considered having an adjustable thrust line similar to a trim tab in use. I have spoken to several aerospace engineers who have suggested that it may be a good idea to calculate the nominal location and then tweak it during flight testing. Eventually the final "found" setting can be designed into a simple mount. the thust line could be made to adjust in x and y to counter act torque too.

Tweaking it under a series of throttle conditions in combination with drag and pitch changing conditions (flaps and gear) to establish the best compromise with safety in mind (least pitch change during critical moments i.e. takeoff).

Some designs place high centre airflow over the Stab. to act like a self regulating pitch dampener. The problem is then the controls feel ineffective with no power. or too sensitive at high power. ???

The best thing i can do is very accurately figure out the CG, the centre of lift and give the machine the longest tail moment possible. I often consider trying to place major structures in such a way as to keep the thrust as close to the cenrte of mass as possible but it leads to complicated mounting and potential safety problems associated with engines behind humans. It's a pain in the ass!

Rotax also won't warranty the engine if the 412's turbos and air boxes are moved from below to above. The Rotax 9 series can't be operated inverted either. the predator drone has done it successfully but i have been having a hard time getting my hand's on one!

craig saxon

Well-Known Member
Sep 26, 2010
Canberra, ACT, Australia
I believe that when Happy Miles went out of business due to the structural issues with the adventurer, a group of builders hired Martin Holeman to do an analysis of the design. I dont know how you will get in contact with them, maybe you could contact Holeman. I've copied here a thread on the Adventurer that was on the seabuild Yahoo site which makes interesting reading.

Re: [seabuild] Adventurer 2+2 Amphibian brochure uploaded to files

TO: 1 recipient
Show Details
Message Body
Met Happy Miles (actually put him up for the night) on his way to Sun-Fun to
debut the plane, it was pretty rough, he admitted to having a quarter
million in the project at the time. Wonder who got it?

One of the early ones came apart, group of builders hired Martin Holman to
run a FEA on it and he found a problem with a certain speed at half tanks if
memory serves.
He had marginal engineering by his own admission over dinner and that is a
recipe for disaster. Also pretty heavy.

He told the story about a guy calling in to order one while they were still
in the plug stage, guy was 6'6" tall so they just decided to raise the roof
, engine 4" to make it fit him with no regard for the other dominoes that
started falling as a result of that change.

Real piece of work, stay clear.


-----Original Message-----
From: coraview2000
Sent: Tuesday, June 07, 2011 1:29 PM
Subject: [seabuild] Adventurer 2+2 Amphibian brochure uploaded to files

I came across a brochure I received at Oshkosh in 1993. It's on the
Adventure Air 2+2 amphibian that was kitted in the 90's. I also remember
seeing pictures of this aircraft with a Chevy V8 engine for power.

All composite, 4 place. I don't know what happened to the company or how the
aircraft performed.

Maybe some of you can fill in the blanks.



Jay Kempf

Curmudgeon in Training (CIT)
Lifetime Supporter
Apr 13, 2009
Warren, VT USA
I know an old thread and all but does anyone know if and where the tooling for this airplane is? Project, engineering, current owner, kits, etc...?