Rocketeer - Flying Model Rocketpack!

Prop-Builder

I had always fancied putting real working rocket engines into the 14" vinyl figure model kit of the Rocketeer. Remember the scene in the movie where Peabody tests the pack on a wooden statue in a field? This is what I wanted to re-create right down to the cable/chain that keeps him from flying off.

If I can get it to do this, then maybe I'll release the cable during later launches and see how far it goes! I have done some firing tests with rocket motors mounted to a rig to see how long the burn time is, but it seems keeping them stationary like this greatly reduces the time the engine burns. The best I can get is around 2 - 3 seconds, but I know that these rockets last a lot longer if launched properly. Maybe once they're in the jet-pack and flying through the air, they'd perform better? By the way, these particular engines are 15 years old, so they might not be performing as well as they should due to age?

Here's a video I did a while back of a burn time test.

Model Rocket Engine Firing Test - D size Engine - YouTube

vistaVision

Your posts are always entertaining! I don't for a moment believe that you're working on all the strange stuff you claim, but I'll play along for the fun of it. The thrust duration of the type of model rocket engines you picture is not going to exceed 3 seconds. In fact, many of these provide thrust for less than 1 second. Your rocket spends most of it's upward flight unpowered and coasting. You really don't need to perform thrust tests, engine mfg. data is available online. Good luck with your flight tests!

Marcus

Prop-Builder

Thanks for your post Marcus. When I did those thrust tests in the garden late last night in the dark, the nosy neighbour on our block came out of her flat/apartment concerned with the strange whooshhh sounds and smoke coming from the garden nearby. After just 2 second tests, all I could hear from the other side of the garden fence was her jabbering on with her mate about what she heard and trying to find out what it was. I thought she was going to call the police at one point, so I opened the back gate and told her not to worry...just me playing around with a few fireworks (she wouldn't know about rocket motors I shouldn't imagine, so I said fireworks).

I framed the video to show at least the 6 inches of flame shooting out of the engine, and was surprised to see it go 3ft or more, so most if it unfortunately is not on film. At least the rig stayed still this time, the last time I tried this (15 years ago), the older rig flipped across the lawn and ended up in the pond.

Link to engine firing test video is here: http://www.youtube.com/watch?v=J6LE6klWXLA

Nwerke

Now this is a more achievable project, but once again I fear you are heading off into territory that's not achievable. You won't get hover with a model rocket engine, as Marcus explained. Also, you really shouldn't mess with the engines at night in your garden, because things will not only end up in ponds, police may be called too, etc etc. Lecture over.

What you CAN do with this is make a flying figure, that should really be achievable. If you're not already aware, model rocket engines come in several types. The most common type has a small explosive charge for blowing a parachute forwards out of the nose of the rocket. You want that type and some means of fitting a parachute in the rocket back also, or, you want one of the types that has no ejection charge, and a timer arrangement somewhere else for the parachute; in his body maybe.

You will need to do some stability experiments because it won't just all work like it does in the film, the dynamics probably aren't right. You may need to add a transparent tail, and keeping it out of the rocket wash will be tricky. Should make for some fun experiments!

Don't burn yourself.

Prop-Builder

Great info! Thanks.

I wondered if you know anything about the miniature model jet engines available? I always wondered if these things were able to lift their own weight and more... and after reading through some of the info on them, it seems they're actually able to lift up to 10 times their own weight? This seems to good to be true. I may have mis-understood, but an example of one engine was:

Engine thrust: 18 - 20 kg
Engine weight: 1.7 kg



I also found some interesting videos on Youtube on making your own 'rocket candy' rocket fuel. They have much longer burn times, such as 11 seconds for a 1" length of fuel! Any amount can be made so I guess I could make longer sticks to put in the rocketpack. My main question is the power/thrust they produce, but I saw videos of rockets launched with rocket candy as the fuel, so I guess they have enough power to launch a lightweight rocketeer figure (even if I have to cast it with a much lighter material). See this video for making rocket candy: http://www.youtube.com/watch?v=Cf8az...eature=related

Mechinyun

This is cool.. fire it up!

EvilRocketeer

You are a sick sick man. haha

Don't forget to film your attempts!!! I would love to see this.

Nwerke

Any time. If you come up with something it will be fun to see.

Not that much. I was a pretty keen rocket guy 20 years ago, but never got into anything more advanced than gliders on the aircraft side. I build RC scale stuff, but only to "hangar queen" status. Jets would be out of my price range even if I did fly.

Nope, they're pretty cool little things these days! They've come a long way in only 15 years or so. But, if you want to build a jet-powered version, it will have to be a lot bigger. Also keeping weight down will be more critical than ever. You'll have the highest possible wing loading, ha ha...

I have made this stuff. I can tell you it is not easy to get serious power out of it. You need to have pure ingredients which I wasn't able to legally obtain. You also need to grind everything very finely, and take great care with the process lest you blow up your kitchen, and even your house.

I blew a modest hole in my back yard, but never got anything to fly properly with it.

Prop-Builder

If I was to do a jet powered version, I could do maybe a 1/2 scale Rocketeer figure and backpack. The backpack would then be around 12" long (1ft), and I could go for some of the smallest jets for this.

I have always wanted to build a Rocketeer rocketpack from scratch, now this would give me that opportunity!

I'm a bit puzzled to how the casings for the rocket candy fuels are made so tight around the fuel itself, so the pressure is contained and directed through a small nozzle? Is it simply a case of slipping a stick of this stuff into a snug fitting cardboard/plastic tube? The commercial rockets casings are always so tight around the propellent, and I assume this is a must for best performance?

Nwerke

1/2 might work. Hover would be your only flight mode I think, and you would have very low endurance - the rig wouldn't lift a huge amount of fuel. If you can't keep it light enough to shoot off like a rocket then a tail won't work to stabilise it, so I have NO IDEA how you could possibly make the dynamics work, unless you ran it on a wire or something. Not to say it can't be done, but again, it's getting dangerously advacnded!!

Try the model rocket approach. Safer, cheap, more likely to succeed, probably a lot more fun too.

Oh, re rocket casings, you can pour the explosive toffee mix into the casing itself and let it set. If you make it hollow-core you get a briefer burn but higher thrust (because the available surface area of the fuel is increased). You can use a removable insert to achieve that. Inserts can be star-shaped, to really ramp up the surface area. Cardboard tubes used for model rocket engines are thick and very high-density, made for the purpose. Do NOT use a toilet roll, OK?

Actually don't use anything, just don't do this at all. This isn't safe stuff to experiment with and you should have a pyrotechnician handy or you will hurt yourself. Go for the commercial model rocket engines. They come in sizes that are TOTALLY powerful enough, and then some.

I was a stupid kid who was inadequately supervised and was lucky not to blow myself up. Don't be me.

Contec

Make a 1/1 and you can strap the rocket pack on yourself

Prop-Builder

I don't know what the laws are in the UK, but I really doubt I could do that legally! With a dummy, I could make it as light as I wanted, but a flesh and blood body would be much more of a challange with thrust and getting off the ground.

At least with a full-scale pack, I could just purchase the 1/1 scale rocketpack and helmet prop cast kits I've seen on the internet, which would speed things along quite a bit! I don't know who made them, but they look very accurate to the movie version (maybe they're cast from the original molds?). I wouldn't however have the fun of building it myself, but as I say, it would speed the project up and make it that bit more achieveable.

Regarding the 1/2 version, I wondered how to make the thrust on a twin engine pack balanced so the Rocketeer would have a stable hover and not drift about to one side? I would prefer 2 engines as it does have two outlets, and there's more room in the cylinder parts anyway. I planned on putting the electronics, servos etc.. in between where the little fan unit is.

Firemedic

great movie....love Jennifer Connelly =)

Too Much Garlic

You'll melt the vinyl.

Prop-Builder

I plan to make a resin casting of whatever figure scale I intend to use. I think it's just the pack itself and the legs I will need to heatproof. I'd probably have a bit of fun with a small figure and some hobby engines, then maybe move on to 1/2 scale with jets. Ironman has my interest too, but a 1/1 flying suit would need the jets mounted into a backpack, which just isn't true to the much loved suit unfortunately.

Nwerke

Ahhhhh...jets. We are talking what here? Jets for radio control model aircraft?

Are you aware of how many completely successful VTOL RC Harrier models have been built? (Answer: very few and it took forever to do.) Do you know what RC turbines cost?

Again, I hate to rain on anybody's parade but this is something that absolutely expert RC modelers/engineers struggled to crack...

cayman shen

Did I miss something Prop-Builder or did you just pick up a two year old conversation as if there had been no gap whatsoever?

Prop-Builder

There has been quite a gap, but I never intended to give up this project. I realise RC jets are expensive, which isn't a problem. I've seen 'pocket-sized' jets for around £1200 (a few years back) and I guess they go up into thousands from there. I had also seen model harriers using petrol engines which some owner stuggled to fly. I'm not saying this project is going to be easy, and I like a challange. I'll do the 14" figure with solid fuel mini engines and see how it all goes from there. I just found the old vinyl backpack in the drawer, so I will make a silicone mold of it and do some resin pulls.

Here's the model kit:

Prop-Builder

Who doesn't love Jenny!!!

Does anyone have access to a Rocketeer vinyl kit? I found the rocketpack and helmet, but the figure is missing! I guess I could sculpt something to represent the wooden statue, but if anyone can think where I can find a kit or just a 17-18" tall action figure, that would be a great help..

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Nwerke

OK, if you've got the budget, anything can be done. I reckon the best bang for the buck would be a model rocket version, mesself - that'd be a ton of fun in fact.

The larger jets cost many thousands to buy and to operate. They need maintenance etc. You can certainly get hover out of them, there are some nice Youtube vids of people hovering things like large Su-27 models and that kind of gear (you pop it on its tail and just balance it - pretty impressive).

The dynamics of that are fine, but the dynamics and mass distribution on a figure with backpack are very different. Still if it can be done in RL...anyway, it'll certainly be challenging, will be interesting to follow though. Good luck!

Prop-Builder

As many rocket bodies are just cardboard tubes, I thought the easiest way to do the backpack is cast it in resin. But, the rudder plates would get burnt as they're in the path of the flame, so might have to make those separate with sheet metal. I'd probably make those adjustable anyway, as in the film. I still need to get hold of a cheap figure the same scale as the Rocketeer figure. I believe he stands 17 inches tall. Can anyone advise on something available? I guess I could sculpt a mock up of the wooden statue Peabody used, but would rather just buy something ready done and modify it. I'm molding the backpack right now, so I'll post some pics of that soon.

Prop-Builder

Ok guys, here's a pic of the vinyl rocketpack being molded along with the helmet. I probably didn't need to do the helmet, but I had some silicone mix left, so just used it up that way. I will then do a hollow cast in Urethane resin and decide from there what size engine I can fit into it.

I still need to find a figure I can use, but haven't had much luck with the correct scale. I think it 1:5 scale, but will need to do more research. Btw, has anyone done a full-scale rocketpack here? I may buy one for the larger experiments, but more likely would prefer to do my own from scratch.

Update!

I have now completed the mold and am ready to cast a resin shell. I have 3 engine sizes to choose from. The largest 'D' size type is plugged, so doesn't have an ejection charge, but is a little more challanging to fit into the pack. I should be able to cut down the excess card at the top of the tube though as it doesn't look like it's doing much but creating more length.

I just discovered that the figure I will need is 1:4 scale, and have found some good pictures of the statue figure from the film that was used as a test rig for the Rocketpack. There're also replica Rocketpack 1:1 scale kits at MonstersinMotion that I may consider buying for the Jet Engine version later.

Update 2!

After a bit of measuring, I estimate the statue should stand approx 40cm tall. I'll probably just do a rough sculpture and cast it in resin (hollow). I'm assuming adding weight to the feet will help keep the figure upright when flying vertically through the air?

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Prop-Builder

Some updates on the rocket pack project. I've cast the rocket in resin and started opening the exhaust vents. The pack is hollow of course and will need to do some grinding and fitting of rocket motor mounts.

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