# Preliminary design of a ultralight aircraft amphibian like Aircam

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#### ultralights

##### Well-Known Member
I am working about a preliminary design of a ultralight aircraft amphibian like Aircam configuration,
but single pusher 80 hp Rotax engine, tandem, aluminum wing with fabric covering, and composite fuselage, floats and tail surfaces.

I would like to hear your opinions about retract landing gear systems and
which would be best :Mechanical, electrical, hydraulic or pneumatic for a ultralight aircraft?

##### Well-Known Member
You might be better off with a steel tube fuselage and a composite cockpit with all the hard points molded in (stick, seats, belts, attachment, panel, the lot).

A composite wing with a double-slotted Fowler flap might allow a big decrease in wing area and weight, without handing in any performance penalty (climb, cruise etc)

#### ultralights

##### Well-Known Member
Dear Autoreply I have many components for typical aluminum/fabric wing construction: spars, struts, leading edge mould and trailing edge slotted mould that I prefer to use for project.

#### Kyle Boatright

##### Well-Known Member
Look at the Lockwood Drifter. It is basically what you're considering.

BJC

##### Well-Known Member
In that case a composite wing would be ridiculous. Why going for the composite fuselage? Steel tube, Rutan-Style tail surfaces (lightest) and a composite seat would be how I'd do it.

#### ultralights

##### Well-Known Member
I believe that for a small manufacturing serie that we thought making, is justified a fuselage mould. I think that a composite part like a fuselage from mould is more lighter and have best finish, and steel tube with composite cockpit would be more heavy and have more working time because you have that build the steel truss and jig and mould for composite cockpit. Today, laminating a fuselage with infusion technology is a task that require minus work force although more expert. However a steel tube cabane will be use for link composite fuselage with wing structure and for engine support.

##### Well-Known Member
Don't underestimate the huge amount of engineering and labor that's required to design and build a composite aircraft. I'm a terrible welder, but you could probably design a metal tube airframe and knock out 100 before you've got a decent composite design + mold.

Yes, it can be made much lighter, I estimate about half of the weight of a steel tubed, fabric covered one as long as you have free choice of shape (you need a fairly thin diameter boom to make it worth it), but designing is pretty involved; much more so around any odd shape (openings, kinks etc). If you do so, integrating a composite pylon makes a lot more sense; much lighter and integrating control- and other hard points then saves a lot of time in manufacturing. (aligning an airframe can be a major PITA)

I'd also have a good look at the VW's. Less power, heavier, smaller prop, but about a third of the price of a 912(S). More span and as light as possible goes a long way in performing better on less power.

#### ultralights

##### Well-Known Member
I can understand how to design, simulate, calculate, characterize, testing and build in composites luckily. Although and luckily the composites is a continuous learning. Why I not prefer a pylon is that the copilot is caged. The amphibious ultralight planes this thought is for enjoy the nature face to wind. I live neighbour to a 70.000 hectares lake´s, a 1000 km long plain river and to 300 km of a wetland unique in the world. The outside temperatures are gentle most days of the year so, open cockpit is a option. I have some experience in VW conversion (1800 cc), I not like this option, less in pusher configuration. I prefer a simple Rotax 582 engine. I have calculated a span loading compatible with 65 hp for acceptable climbing performance ( I have a new 582 in box for the prototipe). The 80 hp Rotax is a best option but more expensive I accept.

##### Well-Known Member
Understanding can be misleading. Hard to judge how far somebody on the other side of an LCD screen is ;-)

Pylon? Sure about that? Tails are often underestimated in weight, so you might have a look at C of G? Ballparking I'd expect the pilot has to be very far fwd to put the pax in the C of G.

Put the passenger on the 25% chord point and there's plenty of space for a sleek pylon. Using metal tubed uprights, while using a composite "fuselage" pretty much defeats the purpose.

As for the engine; most manufacturers go through that phase. They design for a 582 (it's not even made anymore...) or another two-stroke, find out that nobody buys it, have to move to the VW or the 912 and now have an overweight plane with C of G problems.

Sure, some people buy it. But I've yet to meet the first pilot that buys a 2-stroke powered aircraft (unlike it's a trike/paramoteur/sailplane) as a second or later purchase. Opinions about 2-strokes might vary a lot... the market realities do a hell of a lot less.

#### ultralights

##### Well-Known Member
Understanding can be misleading. Hard to judge how far somebody on the other side of an LCD screen is ;-)

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Yes, but this is only a simple chat about planes that we are passionate

Pylon? Sure about that? Tails are often underestimated in weight, so you might have a look at C of G? Ballparking I'd expect the pilot has to be very far fwd to put the pax in the C of G.
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Tail in this case is composite and fabric covering except fin that is composite integrated to fuselage.

Put the passenger on the 25% chord point and there's plenty of space for a sleek pylon. Using metal tubed uprights, while using a composite "fuselage" pretty much defeats the purpose. As for the engine; most manufacturers go through that phase. They design for a 582 (it's not even made anymore...) or another two-stroke, find out that nobody buys it, have to move to the VW or the 912 and now have an overweight plane with C of G problems.
That you can see in the first post of this thread I tell about a desing for 912 engine. So I have seen what you say about cg. Put a venerable 582 with cooling system and battery all join is similar that 912 with cooling system and battery more near to CG, if is neccesary with a bit long engine mount you fit (for 582). Even more, in this pusher configuration the power system is more near CG that a typical tractor plane , so engine weight is a little less sensitive for cg seting. For this and a few more things, simple truss tube cabane allows me play a little more in a prototipe that a pylon.

Sure, some people buy it. But I've yet to meet the first pilot that buys a 2-stroke powered aircraft (unlike it's a trike/paramoteur/sailplane) as a second or later purchase. Opinions about 2-strokes might vary a lot... the market realities do a hell of a lot less.
Sir, exist several reality around of world, you would be amazed that two stroke engine resold, resold, resold... in these places :gig: You europeans are rich with plenty of 912s .:roll: More serious, a while ago I was visited by a very interested french homebuilder, they were interested in a cheaper ultralight with two-stroke engines( french man like Hirth) tired of so expensive aircraft, so I guess Europe also there builders interested in two-stroke engines....
Last, of course I know that 912s are most selling engines today and think that is a ideal option, or another water cooled that D-Motor?

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Note that the VW's are typically as expensive if not cheaper as your typical 2-stroke. Great Plains, Aerovee, Revmaster and Hummel all end up at 7K US$or so, once you opt for a starter, alternator etc. Many of us are not rich, they either drop out of aviation, share the cost (multiple owners) or opt for an affordable engine (VW, or the BMW boxer options) #### ultralights ##### Well-Known Member Note that the VW's are typically as expensive if not cheaper as your typical 2-stroke. Great Plains, Aerovee, Revmaster and Hummel all end up at 7K US$ or so, once you opt for a starter, alternator etc.

Many of us are not rich, they either drop out of aviation, share the cost (multiple owners) or opt for an affordable engine (VW, or the BMW boxer options)
I have worked with some of this US supplier, my personal experience with VW supplied parts is bad. Ever more, we are neighbour to Brazil were are a lot of VW engines and VW converted engines, but I not know a truly realible VW conversion or have not luck. BMW here in Argentina selling used converted engine already USD13000. I have not experience with BMW in aviation even. The experience with rotax 582 is good and with Rotax 503 very good.

#### ultralights

##### Well-Known Member
I still working about design the ultralight amphib. The configuration has been advance from the first post in this thread. Thanks very much for yours opinions!

#### proppastie

##### Well-Known Member
Log Member
I would like to hear your opinions about retract landing gear systems and
which would be best :Mechanical, electrical, hydraulic or pneumatic for a ultralight aircraft?
I would guess the lightest simplest would be Mechanical, perhaps cable actuated/torque tube etc. Hard to say without more information.

#### ultralights

##### Well-Known Member
I would guess the lightest simplest would be Mechanical, perhaps cable actuated/torque tube etc. Hard to say without more information.
thanks proppastie, I think same, with option to put a electric actuator for the hand actuated system.

#### proppastie

##### Well-Known Member
Log Member
thanks proppastie, I think same, with option to put a electric actuator for the hand actuated system.
Depends on how light you want to be, lightest is no starter, no electrical, no battery, lots of weight there. The lighter you are the better you will perform.