Not MC, but still looks like fun. My other passion.

[MonsterBiker]

Whether it is a crater or a lawn dart depends on how much fuel is aboard when it hits the ground.....

 

If you can keep control of it and land safely you have mad skills. I have built and flown a few R/C aircraft over the years but it would scare me to death to pilot that one. Back when I was ready to move up from an .049 to something with a throttle I bought a Super Sport kit that called for a .15 engine. Since I was planning on using a grass strip the guy at the hobby shop talked me into putting a .25 engine on it......big mistake for my skill level at the time. Take-off roll was non-existent. Hit the throttle and it would literally jump into the air from a standstill. Stand it on its tail and it would climb like a rocket. I managed to crash it twice on the same flight (crashed, bounced into the air, gave it throttle, came back around and crashed again). On that plane's last flight it got away from me and I could not tell which way it was pointing. When we finally found it about a mile away I had to dig for the engine.

[Flyinfool]

Unfortunately yours is not an uncommon scenario. There are very few people that can successfully fly without the aid of an instructor. With the aid of an instructor crashes by beginners are are pretty rare. It is after you learn to fly and start doing silly things that the crashes start happening.

[MonsterBiker]

I actually had a decent amount of experience......with much slower aircraft. That one was way overpowered. Even at 1/4 throttle it was moving much faster than any of the .049 models I had flown before. My current plane is nothing spectacular, but is enjoyable on the rare occasions I have a chance to fly it. It is an electric Super Cub.

[Flyinfool]

I enjoy anything that flies. My fleet ranges from tiny electrics that weigh less than ONE ounce and fly so slow that there can be no wind while you fly. Yes I fly those around inside the house too. All the way up to big planes with gas engines, jet turbine engines and then this monster that I am building.

[Flyinfool]

This post was originally written for a Hobby Machist forum so has more maching detail but we do have some gear heads that like that stuff so I left it intact.

 

OK it has been a while since I posted.

Not much happening with COVID doing its thing.

But I did get all of the TI parts made. It was a learning experience.

 

The only parts that are not TI are the sheet metal band (321 Stainless) and the black screw that is mounting the band (Steel).

All of the small parts came out of that initial bar of 16mm, Grade 2, I bought. The washer and the flat strap are out of a small piece of 2mm thick sheet, grade 5. I did a lot of cleaning up swarf along the way, putting small batches in separate bags so as to not risk anything exciting. It is now all safely at the dump and burried. Most of the tools were HSS with a few brazed carbide lathe tools that were resharpened and diamond honed.

 

The finned part I finally got right on the 4th try. Most of the issue was in order of operations, I got to a point and then realized I could not hold the part for the next OP.

The final order that worked was with the full bar in the lathe, turn the top taper and cut the grooves for the fins with a 1/16 parting blade. The fins are also 1/16 thick.

Then over to the mill to cut the .081 wide slot in the top for the 2 thicknesses of the band to drop into.

Then spot drill and drill the clearance hole for the 4mm screw half way thru the part.

Tap drill thru for the 4mm screw.

Using an end mill, c'bore to hide the head of the 4mm hex socket head cap screw.

Back to the lathe, turn the taper on the bottom of the part and part off to a bit over length.

Turn the part around and back in the chuck to face off to length, drill and tap the bottom mounting hole.

Back to the mill again to make the final .010 wide cut to the bottom of the .081 slot to free the "nut" part.

Finally tap the nut for the 4mm screw.

 

 

I can make anything more dificult.

The 1/4 20 threaded rod was made on the lathe, by facing then center drill and add a lice center to support the end.

Then turn down 5 inches of the 16mm rod to .245. with a LOT of spring passes with a freshly sharpened cutter to get the whole length the same diameter. (I sure wish I had a follower rest)

Due to the center I could not turn it down all the way to the right end.

I then single pointed the thread leaving some unthreaded at both ends. Again a lot of spring passes with a very sharp bit.

I then parted off the end with the center, then the other end.

I slid it into a piece of thin wall aluminum tube to chuck it up to face and chamfer both ends.

 

The nuts were made by milling the hex onto the end of the bar first, long enough for both nuts.

Then the whole bar into the lathe to drill and tap, and turn the little shoulder, and part off twice.

Then the nut went back in the chuck to face and chamfer the other side.

I used a piece of steel that had a 90° c'sink in the end and a hammer to slightly close the top of the nut to make it self locking and able to still handle high heat.

 

 

These are the glorified washers that will go on the top and bottom of the wing, the long one is also the attach point for the catapult release.

These were made out a 2mm x 100mm x 100mm sheet of grade 5 TI.

First I made the round one, on the drill press I used a 1.25 dia hole saw to rough it out. Worked great since I needed a 1/4 dia hole in the center anyhow. I then took a chunk of scrap in the lathe and drilled and tapped 1/4-20, I used this as a mandrel to hold the disc for truing the od to final size and putting on the chamfer, one side only. Done easy.

For the oval part I bandsawed out the blank, drilled the 2 holes and the rest was done on the belt sander. The outside shape is not at all important so I did not bother to set it up on the rotary table to make the ends perfect, and they are not, but it goes on the bottom of the wing so no one will ever see it.

 

 

This is the front motor mount.

With the bar mounted horizontal in the mill, I milled the top flat, then side milled the 2 short sides, and the top (side near the thru hole) then drilled the through hole. then put the corner radius on 2 of the edges.

Then to the band saw and cut it off a bit long.

Back to the mill, layed it flat on parallels with the round side up and milled the final side and put in the final 2 corner radii.

Then stood it up to finish miil the bottom to final length, and drill and tap #10/32 thru to the cross hole. The threads are just a bit short as I ran out of tap length but it will be fine.

 

 

 

I am now deep into building the test stand, With some luck It will be done by the end of next week and I can see if I can actually get this monster to light up. I will try to get some video of this. It may be exciting, I have never set up or run any kind of pulse jet before, I am betting I will start some fires before I get it working right and figure out the correct fuel flow rate.

[SilveradoCA]

RC airplanes were my father's hobby too. He built all kinds: electric powered gliders with di- and poly-hedral wings and folding props (one of which had a wingspan of at least 8'), tons of high and low-wing gassers, and a really cool bi-plane that he built before I was born. Some of them were amphibious; floats with wheels in them, just like a bush plane. He started me off on a control-line flyer with a Cox .049 Black Widow on the front, and eventually even browbeat me into building a model Piper Cub. It was never really my thing though, since he plunked me down on a Honda Z50R when I was 5.

 

The day he showed me how to make Immelmann turns was close though.

 

One winter he built something similar to this, from scratch. It was a delta wing with a boat hull shaped into the bottom. Yeah, we spent our weekends at a lake, and he wanted to be able to take off and land sitting on the dock. The entire airframe was shaped from Styrofoam SM, covered with laid-up fibreglass, then filled, glazed and painted. The paint job was primo, because he was a Master Auto Body mechanic, owned his own shop, and was a lifelong hot-rodder. The oddest thing about this odd thing of his own design, was the huge 4-stroke (!) engine mounted at the top of the tail. I don't remember exactly, but I don't think it was backwards with a pusher prop. May have been though. Where else would you locate the motor on such a thing?

 

It took him most of the winter, and I recall he said that it didn't fly for ****, but sure made a poor boat. LOL! He had far more creativity than I do, and I wish he had lived longer. Maybe some of it would have rubbed off; a lot of his other traits certainly did.

Edited September 12, 2020 by SilveradoCA

[CaseyJ955]

I saw something like this fly at Machias airfield, I had not even know these existed in scale, very very impressive!

[Flyinfool]

@SilveradoCA, There are several ways that planes of what you describe are powered, it could be a forward mounted engine, it could be a rear facing engine with a pusher prop, Some engines can be changed to run in the opposite direction mounted facing backwards and a standard prop spinning backwards will push.

 

I got started in all this nonsense about 52 years ago.

[Flyinfool]

Well I did get it out to try to light it up today. I got a bunch of pops a few farts and a couple of really loud BANGS. The longest it ran was about 2 seconds. It was like it was just burning off the prime, I can tell it was getting fuel by watching the level in the tank go down.

I have no clue as to just what flow rate I should be using, so this is all trial and a lot of error. All of the batteries are charging now so I may give it another try tomorrow with a different fuel mix and see what happens.

[Karaboo]

Will I be able to see the carnage from here?

[Flyinfool]

You may not see it but you should be able to hear it from there.