Fixing the HobbyKing pulsejet (part 2) 

I find it interesting how more and more people seems to notice the weather is out of the ordinary. Warmest december in Sweden ever! Maybe all the heat from NZ went to the northern hemisphere?

Great video! It wouldn't surprise me if the pre-heating with the heatgun started the micro fracture - what terrible quality. It'd be great if HobbyKing offered you a replacement, or removed the product for sale as being defective.

Hey Bruce! I was so shocked to see this follow up in my news feed but once again you have inspired me to pull an almost forgotten piece of hobby awesomeness and have another go at getting it going! :D Keep up the good work mate :D

It was 15 C here in Cornwall, Ontario on Friday. I am loving it. :)

you shouldn't have to do a damn thing to these motors. They should run right out of the box without correcting faults the manufacturer should have done before they even went on the market.

I wonder if the paper thin ground joint is a common feature of all of these motors, or if this is just the unlucky bad one that Bruce has got. Has anyone else bought one and had success with it? Knowing HK quality control, it wouldn't surprise me if the 0.9mm fuel hole was fine for another motor, and it was just the large manufacturing tolerances messing this one up. I'm very keen to see the next part of this video Bruce. Now if you can just make all the other part 2's that have been promised over the years, we'll be in luck! :P

Those drill bits have gone up in price now. I still have 5 new packs left :D Shame about the blow out on the motor!!

I know why its cold over there: We have all your heat over here! Its like 80deg Fahrenheit here in florida, in December! Its the warmest december I can remember...

Sets of metering can be had/made, and play a big part run stability, starting ease and reed life. IIRC a set of about 10 or so went by number drill sizes, and selection was a function of OAT, RH, barometric pressure, fuel blend, tank position within the specific model engine combination, star/planet alignment along with 8 or 14 other parameters. Metering jet selection was a 'black art' but once determined, things went smoothly... until something changed a little.... BTW, I looked a little last night and saw a someone using a leaf blower for starting! That would allow complete removal of the start nozzle; looked pretty clever! (Bicycle pumps were the starting norm back in the day...)

Great video Bruce. Hope you don't go crazy trying to repair the tailpipe. Looking forward the the Mini Talon first flight.

Great Bruce, really looking forward to seeing you weld with the tig , would love to see some how too videos on mig and tig , very helpful mate

I have entered the engineering side of youtube.

I never get your book you published years ago to learn about pulse jets since you are the expert. I think it cost me $5 but it was years ago so I just gave up on trying to get a copy.

Cant wait to see the welding repair and it flying.

Thanx Bruce you are a star !!

The crack is not in the weld itself, but in the heat affected zone. So the thickness might not be the problem, but the chosen steel grade and welding skill. But definitely crap ;)

when you weld stainless, the back side has to have a shield gas or a back-side flux applied, so this also did not help the ground-weld situation out. It is VERY common for Chinese built Automotive Exhaust system manufacturers to not protect the back side of the weld...It "cauliflowers" if not.

I think the Dynajet came with a neoprene tubing but maybe by enlarging the fuel line diameter you could get away with a .9 mm hole or make it less fussy.

Cool how you can see it increase in length as the thing heats up and expands :P

omg this guys sure does take the long way around to get the simplest point across its totally agonizing.

How does the fuel get into it when the level of fuel is lower than the pipe?

Hey Bruce. Good to see that there is at least a possibility of getting this thing to run. You have shown us the difference between the new and old fuel jets, but you didn't tell us WHICH jet you used when you got it to run. Will this engine run on either jet once you drill out that hole?

Bruce, great review as always. Would it be possible to somehow add throttle control on a pulse jet? Also will you be reviewing the TBS Crossfire anytime soon? Your prior LRS reviews were very helpful and I am now in the market for such a system - your opinion matters!

To aid vaporisation in many applications people add acetone.

Maybe its worth buying mini reamers, in silversmith supplies or so: that way you can accurately and gradually make the hole bigger AND measure it with a digital caliper?

Glad you finally got it running but advising on using a gas torch with that fuel soaked piece of wood seems like a potential Darwin award.

I wonder if maybe the motor would run on the .9 mm fuel inlet if the motor didn't have a big hole in it.

i was thinking about one of these but now i wonder if I could get Bob Maddox to build me a little one.

Hi Bruce can you please illustrate how the metering jet works. On starting the engine with your outside air supply I presume it creates a venturi over these two holes on the side of the fuel tube and when started the air pulsing in from the front of the motor takes over and assisted the fuel to enter the chamber for combustion creating a possible atmosphere changing to a negative atmosphere assisting recharging of the fuel. Would a series of smaller holes around the this tube create better atomisation of the fuel, making starting easier, also the venturi affect would be greater when the engine starts. The fitting of a conical ring mounted just before these holes so when the pulses running parallel to the tube enter the funnel shape and increase in velocity and as it emerges over the holes (spray bar holes) in creases the ventri and finer atomisation. Or maybe I'm completely wrong on how this engine works? Chris

If engine is cold you can use ether starting fluid in spray can to start. It will start with one pump.

I'm looking to get into pulsejet models because I now live in an area where I can run it at my house. Obviously this kit is pure crap, I had slightly higher hopes as I can handle drilling but I don't have the setup to do welding/lathing. What would be y our recommendations for getting into pulsejets that isn't crazy expensive but isn't garbage either? Also are there any decent aircraft body kits out there for pulsejet? or just straight build your own?

Congrats on sorting it out, Bruce but yikes! Can't believe how crappy that seam was welded and dressed =( What a pity HK can't find a cheap way to hydroform these things.

Northern Hemisphere cold? It was 61F in Washington DC today and it's supposed to be 70F this weekend (again)! El Nino baby!

Very interesting learning about these pulsejet engines, I think I understand the basic working principles ,but I have some dumb ass questions. Do they require compressed air to operate? and do they need constant ignition ?

I might have to make a valved pulsejet at some point.

This weekend it has been in the mid 70's in Atlanta Bruce. I was wondering how you'd keep it from melting the foam.

Hi Bruce, I'm looking at a small pulsejet, have you ever made an auto-start version? Where you don't need to either blow a leaf blower through it or air compressor? I want to try maybe a small can of compressed air and on-board igniter, and some simple electronic timer to perform the ignition sequence, maybe Arduino? Cheers Dan

Sweet! I would love to see you do a challenge something like an endurance flight on a wing or the like

Is there any good engines that people sell because I would rather not weld? Or is there anyway to make an engine without welding

Yes, back to pulsejets...

hey I have serious question is it okay to use liquid fuel like petrol and fire won't go back in the tube?

The HobbyKing Pulse Jet is a remake of a DynaJet Pulse Jet.. looks exactly like the original !

Have you finished the final part of the scratch built coreflute plane project yet bruce? ;-)

Think ill make a simple butane injector system along with aluminum ball bat and see if it works??

Show us how good you are at welding. I thing that would be great. good luck.

I bet you could repurpose a BSA or Triumph vintage sausage muffler for pulse jet construction. Just finished a nightmare 20g tig tank job. Uhggg

I drill my jet and is working great on 100 octanes leaded gas but witch fuel you think can get more thrust ?? I order 2 jet more from hk to make some test

what draws the fuel into the combustion chamber

hi, I have a hk pulse jet also, I wonder if it is possible to internally fix this engine in a jet made of vibrating, of course with the necessary modifications? since already grateful

What in the world is that thing and what's it used for? ???

So you over fuelled it and it broke. Understand why it had restricted fuel?

it wasnt being cooled by flying thorugh the air. Could that have been the problem? They are not meant to run stationary.

Good video

Use map gas in the field to warm up housing.

Thumbs up for a Part Deuce!

13 deg c in the south of the uk the weather has gone mad just like hk selling crap like that pulsejet lol

+xjet You're going to have to try pretty darn hard to do welding worse than what's already on the engine. It's a bit of a worry though about the strength of the rest of the welding.

Don't forget to do the DB meter test after the Pulsejet is repaired.

I get that these engines are crap, well the tailpipes are anyway. Does anyone make or have a source for replacement tail pipes?

where does one buy a decent pulse jet?

Could u preheat the fuel on its way instead?

Dam that thing can blow up on you with welds like that

and what happen with the HK turbine?

Hello, i want to make this one but... how the fuel enters to machine? " xjet

l think it is originally designed for "white" gasoline--use for camping torch/ stove

Thanks

It annoys me that this sort of garbage is still sold. it prob cost $2 to make. your puksejet builds look much stronger Bruce. I would not waste my money on the hobbycrap pulsejet. send it back mate and demand a good one.....

GOOD OLD HOBBY KING SHITE

clearly the design team isnt talking to the manufacturing team. Probably a language barrier....if you know what I mean ;)

Hobby King will give you a new one - NO CHARGE.

did you see that here in the usa we have to get are drones predigested now..$5 for 3 years

C'mon Bruce, it's a good excuse to fix that old TIG.

Why dont you mount it on a sheep???? Did I detect a Kiwi ecsent.

What ever happened to your hobby King turbine ?

Told ya it would be scrap metal Bruce!

You have all the same inflections as EEVBlog >

When will you fly pulsejet planes again

Why not just increase fuel pressure?

its like 40 here in montana.... unnaturally warm. usually sits about -10F this time of year. next moth...-30 before you factor in the 70 MPH winds that are common here. north east montana isnt mountains.... only 1/4 is. but... i wonder.... on my 2 stroke, the colder it is, the leaner it runs. run it too lean, it melts things. as it gets hotter, the air is less dense, same jetting, some fuel....less air....so it runs richer. i wonder if you didnt lean it out and over heat it. a lean fire is hotter than a fat one. sure you up-ed the jetting, but was it enough? was it too lean from the factory? (i think so if it would not stay running) i wonder what that same head and jet would do under 80F temps. it might run right.... still.... its shit work. that weld....i dont weld very often, my dad has a welding cert...he lays lines of dimes. i usually let him do it. butt when the part is not "mission critical", ill weld it up right quick..... and i can do better than that. could do better oxy-act!

Heated or warm fuel atomizes better.

So much to say so little time, it's like ordering a Chinese, really enjoy the video tho

There is no excuse for anything to be sent out to the public like that. Someone like me has no experience at welding on metal like that and shouldnt have to anyways. I bet there are other companys out there willing to manufacture that motor. The only parts you would need is the end parts.

don't you have another youtube chanel? I'm pretty sure I'm subscribed to it, and have been for a while..

how about warranty?

Chinese made?

this Pulse Jet is not designed for bench run it is designed to have air flow constant over the outside and inside that's why it failed

Geez I thought you were going to do your hair there for second with that hair dryer

Yea part 2...........

I would be screaming WARRANTY and good luck welding that.

Crappy engine.... awesome video!!!

After having to do repairs on stainless steel hand rails and balustrade, I guarantee you will be chasing a hole around that pipe

Would an Ignitor, close to a Glow Plug, give betters results than an Spark Plug? See: New Ceramic Pin Glow Plug For Webasto Air Top 2000ST DC12V Blessings +

Try brazing over the bad weld crack

weld it up man

Can't you just run it on butane lighter gas, you wouldn't need a pre-heat when it's cold? The fuel is probably cheaper too from the $,€ or £ store. Now we're cookin' on Gas! lol

Most annoying noise ever. HobbyKing did the world a favour by shutting it up with their crappy build.

kinda pointless here in Australia as your not allowed to fly them on rc aircraft

Results are sure hit and miss with this engine. Mine handled ok out of the box, started easily and hasn't split yet with a few minutes of total run time. Yet.. who knows what is to come.

At least they're Taiwanese-made drills and not Chinese.

Par for the course with the cheap fake Chinese stainless steel.