FTFC21 - Seaplane Design & Build by FoamyDM, Junker J-1000

[FoamyDM]

If its not complicated enough already, how could this work? AirHogz? Lol


As massive as 80 meter wingspan would be, imagine the Hindenburg was 245 meters long
I think in real life it would have been better off in the water. Every time the tail wheels touched down everybody would spill their beers and ashtrays lol Cool project. Im kinda concerned about what cross winds will do to it, but I dont know.

@Scotto, regarding the 4-1000hp piston-free Compressed air for the engines, I don't really understand it. I'm sure some who understand the evolution of aviation engines might be able to explain this (please do). Doing a quick wiki search I found that in the 1920s a compressed air starting mechanism was developed to aid against the dangers of starting more powerful motors by hand.

Air-start​

Main article: Air-start system​

Cutaway view of an air-start motor of a General Electric J79 turbojet​

With air-start systems, gas turbine engine compressor spools are rotated by the action of a large volume of compressed air acting directly on the compressor blades or driving the engine through a small, geared turbine motor. These motors can weigh up to 75% less than an equivalent electrical system.[15]​

​

The compressed air can be supplied from an on-board auxiliary power unit (APU), a portable gas generator used by ground crew or by cross feeding bleed air from a running engine in the case of multi-engined aircraft.[19]​

​

The Turbomeca Palouste gas generator was used to start the Spey engines of the Blackburn Buccaneer. The de Havilland Sea Vixen was equipped with its own Palouste in a removable underwing container to facilitate starting when away from base.[20] Other military aircraft types using ground supplied compressed air for starting include the Lockheed F-104 Starfighter and variants of the F-4 Phantom using the General Electric J79 turbojet engine.​

​

Advantages​

Compared with electric starters, air-starters have a higher power-to-weight ratio. Electric starters and their wiring can become excessively hot if it takes longer than expected to start the engine, while air-starters can run as long as their air supply lasts. Air-starters are much simpler and are compatible with turbine engines, and thus are used on many designs of large turbofan engine that are installed on commercial and military aircraft.​

Remote Air compressed starters are currently used to start turbine in modern day fighters. They are
In the sims there are model that seem to fly ok... however, those

 

[Hondo76251]

Air starters were a thing in the early years for a lot of things before battery technology cought up.

Shot gun starters too...

 

[FoamyDM]

Yeah, with Ducting, you could start all 4 motors, with 1 air compressor motor for the plane. Lighter than 4 electric starters, I imagine.

 

[Scotto]

Ooohhh no. Ive heard of compressed air starters from submarines to zeppelins. This is a whole different animal. What was proposed was a

Free piston engine (4 of them) with no crankshaft, pumping air to turbines geared down to props. Thats new to me. Very creative thinking. It could probly save alot of weight and have the engine weight far away from where you want props. I think of it like an external combustion turboprop.

 

[FoamyDM]

Ooohhh no. Ive heard of compressed air starters from submarines to zeppelins. This is a whole different animal. What was proposed was a Free piston engine (4 of them) with no crankshaft, pumping air to turbines geared down to props. Thats new to me. Very creative thinking. It could probly save alot of weight and have the engine weight far away from where you want props. Cool.

That's is the exact language but I need a translator for engine talk so research it I will.

 

[Scotto]

That's is the exact language but I need a translator for engine talk so research it I will.

Dont worry about it. They decided against it anyway. I just think its an interesting concept even if it never happened.

 

[FoamyDM]

I went back and checked the CG Calc here: Link to recall J-1000

The results are 3/4 to 1 1/8" behind the LE of the main wing. I suppose there nothing but to build it.

 

[DinosEatPeople1]

I went back and checked the CG Calc here: Link to recall J-1000
View attachment 198573
The results are 3/4 to 1 1/8" behind the LE of the main wing. I suppose there nothing but to build it.

I personally would glide test it around the apex of the airfoil, or the center of pressure.

 

[FoamyDM]

I wing loading of ~3 is VERY light... Meaning, it could be loaded up.
I could be loaded with +1.75 kg of load before pulling out of Scale flying range. Which could make this a VERY long range vehicle.
I need to mark the CG on the plans

 

[FoamyDM]

I managed to get some time tonight to cut out some of the plane I'll have some more to cut out tomorrow and start folding it together. I did something new with this that I forgot about.
I am going to iron the edges on the top and on the front edge in the back of the leaning of the trailing edge that way it effectively becomes like a Clark Yh.

I'll

 

[FoamyDM]

So after looking at some critical dimensions. I realize the bottom plate is perfect at 9.3" where the top is measuring 9"... it is supposed to be 10"... Yeah so that's a thing huh? the center section is correct. This is a simple fix I have updated the plans. I am reserving a Beta release until I have finished the build.

I am Wondering if I should project the floor plan onto the bottom section and start some scale features. (maybe set up a few mock cabins for an FPV "Passenger" or two.) I suppose I should get me built and flying first.. right.

I also Finished cutting the rest of the wing. I will admit.. that even with the can files and references, I cannot remember how the spar goes together, or exactly where it should be placed. I see three verticals. one much shorter. and the middle is doubled. the main spar looks straight along the back with a taper, but it should be the vertical with a straight top and a tapered bottom... When I figure it out... I will mark, illustrate and update the plans.

wing section

wing section over the drawing...
clear as Mud.

 

[jfaleo1]

Air starters were a thing in the early years for a lot of things before battery technology cought up.

Shot gun starters too...

Air starters and shotgun starters are still a thing, just not on piston engines so much.
Most large jet engines use air starters not electric due to the huge power consumption to get a large jet engine turning fast enough to reach self sustaining speeds. even at the size of the Citation X the RR AE3007C uses an air starter, supplied by an APU (small jet engine in the tail) that is electric started. The An-124 used to come in to Wichita and it used "shotgun" starter cartridges. But they would have been for a HUGE shotgun. In reality it only used one and the other 3 engines used air from the first for starting.

And now the I will step of my teaching podium, but I would be happy to talk more about the subject, to think they pay me to.....

 

[Hondo76251]

Although considerably smaller than the large jet engines, the turbine engines in the helicopters i used to work on were still electric start but this did require some trickery. They would begin start up with the batteries in parallel then, as the engine spooled, switch to series to spin the rest of the way up...

 

[jfaleo1]

Although considerably smaller than the large jet engines, the turbine engines in the helicopters i used to work on were still electric start but this did require some trickery. They would begin start up with the batteries in parallel then, as the engine spooled, switch to series to spin the rest of the way up...

most of the Citation business jets use electric start as well. but thank goodness they don't have a system like that.

 

[Tench745]

So after looking at some critical dimensions. I realize the bottom plate is perfect at 9.3" where the top is measuring 9"... it is supposed to be 10"... Yeah so that's a thing huh? the center section is correct. This is a simple fix I have updated the plans. I am reserving a Beta release until I have finished the build.

I am Wondering if I should project the floor plan onto the bottom section and start some scale features. (maybe set up a few mock cabins for an FPV "Passenger" or two.) I suppose I should get me built and flying first.. right.

I also Finished cutting the rest of the wing. I will admit.. that even with the can files and references, I cannot remember how the spar goes together, or exactly where it should be placed. I see three verticals. one much shorter. and the middle is doubled. the main spar looks straight along the back with a taper, but it should be the vertical with a straight top and a tapered bottom... When I figure it out... I will mark, illustrate and update the plans.
View attachment 198814
wing section
View attachment 198815
wing section over the drawing...
clear as Mud.

Looks to me like you did a box spar with a longer and a shorter leg for the center and rear spars? Double the taller face on the center spar. Cut a separate piece for the forward spar?

 

[jfaleo1]

Looks to me like you did a box spar with a longer and a shorter leg for the center and rear spars? Double the taller face on the center spar. Cut a separate piece for the forward spar?

I second that opinion.

 

[FoamyDM]

Looks to me like you did a box spar with a longer and a shorter leg for the center and rear spars? Double the taller face on the center spar. Cut a separate piece for the forward spar?

I'd DOES look like that was the intent. Well I shall find out at the ARCN PODCAST build event. Join me and see this come together live! (Possibly). 1pm through 4pm est

https://fb.me/e/PvEBE2dg

 

[FoamyDM]

I made some small progress yesterday. With the float "aladdin shoes". And I corrected for the 1" strip error on the plans.

Once if figure my spar idea out, it will be time for the wing!

 

[FoamyDM]

Ooohhh no. Ive heard of compressed air starters from submarines to zeppelins. This is a whole different animal. What was proposed was a View attachment 199429 Free piston engine (4 of them) with no crankshaft, pumping air to turbines geared down to props. Thats new to me. Very creative thinking. It could probly save alot of weight and have the engine weight far away from where you want props. I think of it like an external combustion turboprop.

Wow. That animated gif is great!

 

[Scotto]

That hook up on the front of the aladdin shoes is for the flying elevator, right? Are you doing it "as proposed" with no step? Its gonna be big! Thatll be one cool flying wing. All the deltas were getting a little bland imho