Model Jets

nutzboutstuff

Anyone tried to build a model Pulse Jet and strap it to a plane?
I've been looking into chinese, and linear pulse jets, either or these does not have any moving parts...
Could be very very fast, seen some models using them and they can reach about 300Km/h with a couple of minutes of fuel.
What i was thinking was twin pulse jets on pylons or wing mounted, 500ml cannister as central body fuel tank.
Any thoughts?

coolwings

nutzboutstuff wrote:

Anyone tried to build a model Pulse Jet and strap it to a plane?

Yes, it has been done many times.
But a pulse jet is UNBELIEVABLY NOISY. You won't get to fly it in the same place twice.
In model flying fields in Ireland we get noise complaints for a fraction of the noise levels of a pulse jet. I have seen club members run flyers out who just had a badly supressed silencer on 2-stroke engines .... they value their flying field they know what sort of stuff causes problems by now.
That is before you consider the danger to anyone within a 2 mile radius from a heavy high speed model going down.
Kerosene turbines , while dearer, are quieter by far.
Electric turbines are a fraction of the cost, and suit models of .25 - .90 size very well.
What do you fly right now ?

nutzboutstuff

Nothing at the moment, used to have a small trainer, was a small .25cu in and i've a 7 or 8 foot glider. But i got a small pylon engine, you know the type with no carb, and i experimented on running with different tuned pipes, and different fuel types (even added butane at one stage, i wouldn't try that one), and the power output leapt incredibly, although cooling became a major issue
So i've been thinking about jumping back on the band wagon again with something out of the ordinary. Noise wouldn't be an issue because relations have a farm and there is no one around for dozens of miles.
Brother is an architect and a model freak so i might ask him for some help with the plans. Havent decided on a power plant yet, if i can make a working pulse jet prototype, and if i can figure out how to mount two red hot engines...

coolwings

Well, I guess if you can see it, you can try to fly it.
Flying a pylon plane would be good practise for a pulsejet, speedwise that is, but the weight and inertia would be vastly different.
The pylon racer would turn on a dime, whereas the other would take the whole darn visible sky to get it coming back .... :eek:

Here is a delta
weight 6 kilos speed 490Kmh the pilot flys over 20 years esp pulse jets

http://www.greenhobbymodel.com/pulsedelta.wmv

My guess is the best flyers could only keep that level of concentration up for 2-3 minutes max.

I will keep the link for 24 hours but gotta close it then cos its on the data limit, so save it while U can.

nutzboutstuff

That kicks ass, although a couple of seconds and you will end up out of the range of normal transmitters let alone your eyesight.
Is there a speed record for model planes? although you'd have to draw a class as to when model planes become missiles! Someone bringing a tomahawk cruise missile to your local model club could soon claim the fastest 'model' there. I'm thinking something along the lines of a Bell X1 would be a good shape for the model, and with as much power as i'd like to give it i'll have to be strong, and very heat resistant, wouldn't mind giving it a recovery chute either! I've played around with fibreglass before, but this would be a whole new ball game

coolwings

nutzboutstuff wrote:

Is there a speed record for model planes?

How about 250mph for hotliners & soaring gliders?
Dynamic soaring gets a Destiny (soaring glider) to almost 200mph.
And these models cost under €300
Who needs engines ?

The AeroNaut Blade 2 is no slouch either.
http://www.greenhobbymodel.com/movie.html
but I think that the really hot dynamic soaring gliders are the quickest speed for the least €€€ spend.

Patrick's Weasel (not the tiny foamie) is unbelievable. Thing is, these models look like they're stopped while they are going 160mph+ , they fly so smooth.

Even my A-10 can't compete with speeds like that.

When we get the Kestrel club's new field a bit smoother we can do speed trials. I have to get a copy of the doppler effect software first, that's the one that listens to the sound it makes, and then calculates it's speed. More accurate than a radar gun when extreme speed is reached.

nutzboutstuff

Who needs engines? We need engines for vertical ascents!! Plus its all about the noise, without noise it just doesn't seem impressive to the viewer. Have an A-10 on a runway with its afterburners on, if you can't hear it it doesn't sound like a beast that it is...

coolwings

nutzboutstuff wrote:

Who needs engines? .....its all about the noise, without noise it just doesn't seem impressive to the viewer. Have an A-10 on a runway with its afterburners on, if you can't hear it it doesn't sound like a beast that it is...

I can't hear my airframe cutting the air until I fly with engine off or with no engine. My Skyraider sounds a bit like a crossbow bolt passing over your head (if the engine is off and prop folded away), and its not outrageously fast.

BTW I promised a vid of the A-10 engine tests to the forum, trouble is, my camcorder isnt communicating with my PC right now, so it has to wait until I get it sorted. (But it really sounds cool ! )

Fobia

Liking that movie - where's it recorded, and who's flying?

coolwings

I got from 2 sources ... one is Jurgen Helig (?) in Germany, the other Dermot in Dublin who flies in France.
It's hot , isnt it

Fobia

coolwings wrote:

It's hot , isnt it

In more ways than one I'd bet! Those things must get bloody hot at that speed....

coolwings

Let's just say you'd want to have the fire extinguisher not too far from your flight box