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Well-Known Member
Feb 5, 2009
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I have moved discussion of this project under one thread.

The RMX-1 is a demostrator of an idea I had had for a few years. I just combined the Rombus concept with the Roton concept. It is being built from all off the shelf parts.


Rombus model pictures:


Roton picture:

Here is the fruit of today's labor:


The frame is 75% finished. The fixed in place landing gear have been attached, and the wing templates temporarily inserted for placement. The whole thing weighs about 45 lbs., with chainsaw motor, fuel, outer skin, fittings, rockets, etc. I am expecting about 90-100 lbs.

Here is a diagram of the flight profile of the RMX-1:


Originally posted by shrox
Here is the fruit of today's labor:
.......with chainsaw motor, fuel, outer skin, fittings, rockets, etc. I am expecting about 90-100 lbs.


:eek: :eek: :eek: Chainsaw motor?! Whoa! I don't think I've ever seen anything like this before. Talk about ambitious! Just make sure the rotor blades don't actually "lift" it when it's supposed to be descending! Well, this project will certainly bring out the skeptics. I'm interested for sure though. Well, best of luck with this project. Keep us posted.
A chainsaw motor? And whirling blades?

Next you will probably add a sound-proofed hallway, and gutters to catch the blood.

Or am I the only demented one who loves M.P.?
Try to concider how this might be done safely, and your are on track. Obviously safety measures will be taken. The first rotor power test flights will be tethered and confined in a containment rack. I already have permission to use the old, abandoned Eureka airport for tests, including access to the tower. This morning a friend from the local large scale R/C club is coming over to look at it and help me with the control servos. It will happen and I will be rich, or discarded by the side of the road like Tucker...

Testing will be at the old Eureka dragstrip instead. After talking this morning, I found out that area is bigger and closer. The old airport was closed as the town grew in around it and portions have been sold off. Either location has a shoreline, so neither is too close to anybody.

The first test will be on the rotor itself. Just the rotor and driveshaft with a deadweight equivalent to the entire craft, it will be to test the strength of the rotor construction and lift ability. Again, all tethered and confined, with a safety barrier to observe from behind. There are a few free standing walls out there.

Your crazy! :D

Any idea what this could be used for apart from being extremely cool?

And dont forget to put a camera on board it :cool:


I'm sure there are a few others (besides myself) on this board who fly R/C helicopters...
Why wouldn't it work?

Are you planning on a "commercial" rotor head or are you fabricating your own?

And if the 2cycle "chain saw" motor doesn't prove quite strong enough...there are are many larger 2cycle motors (heck...even 4cycle) that power larger R/C aircraft available....

Good Luck on all counts...!!!
RMX-1 is a demonstrator of the ROMAX, a suborbital cargo carrier design of mine.


The ROMAX motto will be, "We can deliver one ton, one thousand miles in one hour"

Almost one third of ROMAX is assigned to cargo. Such a ratio is unheard of in current launch vehicles. Since the rotors do the hardest part, getting up off the ground, gaining inertia and pushing thru the lower atmosphere, the rocket and fuel sections are comparatively small when compared to the space shuttle launch system or the X-33.

Hey Steward,

I'll be fabricating the rotor head. The guys at Murray Field are interested and have offered to help. The fly and repair planes and helicopters.

My advice to potential inventors, move to a small town and get friendly.

Utterly brilliant, Shrox! Good luck with it. However it turns out, it'll certainly be interesting.
Upon seeing this picture of the StratoMax, my wife said "You're going to build real-life Thunderbirds, aren't you?"

I hadn't even thought of that...


Very cool concepts Shrox. Soon you'll have a whole fleet of these things. And as usual your graphics are great. :)
Here is a pic my wife took, you can see how it is coming together. I was applying some glue there I think.

how do you counteract the torque produced by the motor and spinning blades?
do they have a separate power source, or do they run from the same chainsaw motor that runs the rotor?

sorry if you've covered this elsewhere, but i'm intrigued...

I really don't see why you want to design your own rotor mechanism.

There's a whole bunch of commercial ones out there for R/C Helo's. One of them should work for you.

This way instead of reinventing the wheel (OK the rotor) you can concentrate on the rocket part.

BTW it looks like a very very doable project.

Great work so far.

I presume the ducted fans will be driven by a separate power source. I would think Muffin fans might be a good place to start.

Will you be controlling torque via RC or with an onboard servo system?

Do the fans also provide guidance during landing?

What will the rotor blades be made out of?

Also, the biggest concern I have is the strength of materials issue in the blade to rotor joint. Please be very careful as there are few rotor designs ment to hinge that much and still spin. A thrown blade could be deadly.

For the test flight(s) have you considered letting the rotor autorotate?

Finally, if the rotor fails, to you have a backup recovery system...other than a broom? ;)
The details of test first test flight plan were covered in another message. It will be tethered and isolated. The ducted fans are electric. I would like the whole thing to be electric with an onboard generator.


I dont think there are many other sweeter progects out there in my opinion. most definatly in the top 5 most kick *** progects ever done. right up there with the Auroa progect.

any ideas on what motor your gona boost it with. my sugestion would be eather one O5100, or posibly 3 M2500s. or M1939 or M2000. actually 3 M1939 would me the most imprssive at 10K. you would only be able to hear the other ones, not see them.

any ideas on when or whare your planning to launch this brute. probly not by LDRS huh?
Originally posted by shrox
The details of test first test flight plan were covered in another message. It will be tethered and isolated. The ducted fans are electric. I would like the whole thing to be electric with an onboard generator.


A company out of New Zealand, WREN turbines,
that I saw in an other thread here on TRF, makes
a small gas turbine that is used to power generators.
May save you some weight. FWIW.
Great project, BTW.
Good luck. :)
Say...I just thought of a problem...

If this thing is R/C and it reaches 10,000'...ahhh...how can you see it?

R/C is hard enough for me when I can see the model.

Like how do you tell is it is even right side up?

There will be ground support as well. A camera/tracking chair is going to track and transmit to the vehicle, I built one a few years ago, just the chair unit, it was moved manually by the "pilot" thru two upright levers on each side, like the camera chairs in the 1920's movie studios. It will have a zoom camera, still camera and transmitting/receiving antennas. On the vehicle there will be onboard instrumentation, altimeter, camera, etc. and a down link. This a real project and will have real results. My only real concern is the moment the rocket motors kick in, that is the point where something might go wrong and start the RMX-1 tumbling, then the show is over for that one...until RMX-2.

The rotor for the RMX-1 is basically a fixed pitch four blade propeller, with the gas engine throttled. The RMX-2 will work with real rotor hub, a clutch and the blades will swing back against a constraining ring. The RMX-1 is just to see if the basic idea will work and get it on videotape. Investors like videotapes of a working prototype...