home made jet engines?

By BryonLewis (****)

Date 05-27-2009 13:09

Apparantly Kim Jong-il did. LoL

By OBEWAN

Date 05-27-2009 13:09

You should check into the model airplane arena. I have heard that there are now tiny jet engines made for RC model jets. Some people are spending $5-6000.00 on models.

By Mat

Date 05-28-2009 04:46 Edited 05-28-2009 04:49

This link is pretty neat!
http://www.pulse-jets.com/

By CWI555

Date 05-28-2009 14:18

I've participated in a project of that nature. They are on the open market for model air plane builders, but use in model rockets is restricted.

By OBEWAN

Date 05-28-2009 14:38

There is a huge RC field here in Jacksonville. They have all the paved runways, a covered picnic pavilion, a snack bar with hot foods, a bathhouse, yada yada...People come with 1/4-scale models pulled on trailers. They have 4 stroke 4 cylinder engines flying and lots of multi-thousand dollar helicopters. I have yet to see a jet though...But that is where I heard about them. It is only a matter of time before one shows up I suppose. They are flying those ducted fan jet models though...

By CWI555

Date 05-28-2009 19:37

JetCat P-80
Thrust: 17 LB @ 117,000 RPM
http://www.quicktechhobby.com/Engines/QTH%20JET%20ENGINES.htm

Considering the average weight of a model rocket with gyroscopic stabilization is 10 pounds, and that the fuel consumption at 8 oz per minute, you could get 5 minutes at full power with 17lb's thrust. It means it will power up and keep trucking until it runs out of fuel.

Now picture running 4 of these together with solid rocket boost. 10,000 feet will happen in a hurry, and it will be able to get considerably higher before running out of fuel and this with a 5lb payload. This is why the FAA and some other federal laws tightly restrict this kind of thing.

The problem there is, when your thrust exceeds the weight of the aircraft, it can go verticle in no time. Therefore it will be just a matter of time before the feds catch up with the model plane variants.
Add the cost of these little jewels (8 grand in the case of the one I crashed and burned) you can begin to understand why these are so limited and rarely seen.
I would love to be able to produce them and believe that I could, but with the feds catching up to the "alternate" abilities for them, I don't believe they will be legal on the market without specific and heavy licensing in the near future.

By OBEWAN

Date 05-28-2009 19:55

Wow. Those prices are about what I heard from the club. It is too rich for my blood. I don't see how the engine suppliers can sell enough to stay in business. It looks like they have already done some serious price cutting at the site you just posted though. I also wonder if the AMA will charge more to insure a jet like that. I mean, they are going to get heavier and faster...The field in Jacksonville is next to the International Airport too...which is something I have never understood...when I was in college, some crazy RC'ers used to fly next to (parallel) to small planes on approach to the airport...they also used to chase birds...

By CWI555

Date 05-28-2009 20:42

they sell enought to stay in business because dumbA***'s like me will pay it "just to see what they can do with it".

By darren

Date 05-29-2009 05:22

is it legal to build your own rockets and your own fuel for them.
i looked into rockets and how they work and it seems that having a metal tube running down the centre of the solid propellant would sure eliminate the problem of orifice growth and the negative consequences of that. they are really very simple.
i think that the innuendo in your post definitely alludes to why they would have restrictions on them, but restrictions on jet motors would be like restrictions on guns, ineffective at preventing their misuse.
did you help design these?

By Mat

Date 05-29-2009 06:33

When I was younger (15 years younger!), my old man, bro and I used to launch model rockets in the local baseball field back home. I believe almost any hobby shop will have model rockets and the engines for them (a cardboard tube with some form of solid fuel, similar to a firework I believe)

In terms of legality, I can't answer that. I'm sure it isn't any less illegal than convincing someone to blow up a cardboard box with oxy/acetylene...

By darren

Date 05-29-2009 06:39 Edited 05-29-2009 06:42

i know those kind im talking build your own as make your own propellant and have a guided system either through gyros or by radio interface.
real rockets, not toys even though they would be used as toys. would be easy to launch one that went a few miles up and took pics.

By CWI555

Date 05-29-2009 14:06

It is legal to build your own rockets and the fuel for them. It is however; considerably more regulated than is apparent on the surface.
http://www.a2zhobbies.com/rocket_info2.html
Has a pretty good list of A through D solid rockets.
Getting above that is another story.
http://www.space.com/missionlaunches/launches/rocketry_future_000823.html
http://www.space.com/missionlaunches/rocketry_security_030306.html

Our favorite friends the ATF are at the heart of the propellent issue. Yet another power and money grab on their part.

"As a result of the new rules adopted by the ATF, hobbyists that want to continue to handle and fly rocket motors with propellant amounts greater than 62.5 grams will be able to do so by applying for a permit, undergoing a background check, paying a $25 fee and getting fingerprinted."

Oh and then you get into the NFA destructive device stamps.

Let us not forget that the Homeland security act of 2002 took the atf out of the department of revenue, placing it under the justice department along with the fbi, and added a title and new responsibilities to it. They are now the bureau of alcohol, tobacco, firearms, and explosives.

since then, BATFE has been slowly but surely adding to it's list of chemicals that are "explosive or bomb making materials".
http://www.atf.gov/explarson/fedexplolaw/2007edition/index.htm
Therein is a problem for all. They take little groups like the NAR (national association of rocketry) and hammer them. They had maybe 10,000 members, not really strong enough to fight this on their own. The atf in yet another over reaching power grab classified nearly all of their propellents as "explosive". Now the NAR pays through the nose and the more active of their members have been receiving (in my opinion) harrassing visits by federal agents to verify their "propellents and engines".

A word of warning, that fertilizer, deisel fuel, and other required chemicals on a farm, could and have in some occassions been used to arrest and or harrass farmers and others trying to grow food who "voiced" a disagreement with their government.

So much for teaching little johnny a thing or two about rockets, little johnny's dad is going to jail if he teachs to much.

Thats the propellant end.

Now we get to the guided end of the discussion;
This is touched on by so many different CFR's it takes a philly lawyer to sort them out. Homeland security, FAA, FCC, BATFE, FBI, DOT, and many others have a hand in this one.
Your almost guaranteed to step on one or the others toes. If you don't have several thousand dollars to invest in legal research, I suggest staying away from it.

As for did I help design those. No, not those particular ones.

Regards,
Gerald

By OBEWAN

Date 05-29-2009 14:44

This all reminds me of a movie a saw. This kid in high school in the 1950's was a real nerd and a misfit. He wanted to be a rocket scientist and was obsessed with the Russian Sputnik stuff. His dad wanted him to work in the coal mines. He wrote away and got lots of rocket books. He started building his own rockets - with metal parts and lots of welding and machine shop parts...they got bigger and bigger and bigger...and there was a forest fire....he was blamed for starting the fire and arrested...at the end he was vindicated and it was proven that a blasting crew started the fire and not one of his rockets...he went on to win the national science fair...and later in life became a famous NASA rocket scientist who helped design engines for all the major space programs. I forgot the name of the movie...it was in the regular Saturday lineup..

By Revjsnizzle (**)

Date 05-29-2009 16:08

October sky...Pretty good flick

By Bob Garner (***)

Date 05-29-2009 19:28

We built rockets as kids. If I can remember, the best fuel we came up with was a mix of powdered zinc and sulpher ??memory??. We tried homemade gunpowder (75% sulpher, 15% potassium nitrate, 10% powdered carbon ??memory??) but it lacked the briscance (blasting term for oooomph).

We used to get the chemicals from Gilbert, the maker of chemistry sets. Several of us would send in separate orders to "replenish our chemistry sets" so that we could order sufficient quantities.

And I'm sure y'all stuffed match heads into CO2 cartridges and lit them off. YeeHaw!!

Bob G. (still has all his fingers)

By CWI555

Date 05-29-2009 22:33

ammonium perchlorate (oxidizer, 68%) powdered aluminum (17%) iron oxide .8% your favorite polymer (12%) and the remainder in an epoxy and your in business.
(close to the space shuttle srb fuel)

Another cheaper one Potasium nitrate (saltpeter) and sugar. I believe it was a 65/35 split. throw in some powdered aluminum about 10 percent in liue of the 7/3 sugar/potasium nitrate, it will work rather well.

By darren

Date 05-29-2009 19:54 Edited 05-29-2009 20:03

no really dont hold back what do you really think.
i laughed out loud for the whole thing not at the content as it is very serious but the not so subtle im sick and tired of taking it up the three hole from a fascist govt.
sorry i am like most men in that when you see a friend stub his toe or bang his funny bone or blow a fit it makes me laugh because it reminds me of myself when those things happen to me, and at that time i am unable to laugh.
what about the orifice growth mitigated by the metal or other regulated oxidizable tube? seemed a simple solution to what the rocket scientists listed as their one of their biggest problem in solid fuel propulsion.
the batfe better add bat **** and animal fat cause unless i am mistaken that was the first explosive.
" article 163.3.2a it shall be against statute such and such to posses control or otherwise be a party to any feces. also know as **** for the purpose of making any improvised explosive device. in addendum any one caught lighting farts will be sentenced to life in a federal prison with out possibility of parole and any one laughing while engaging in fart lighting or laughing while acting in concert to the fart lighter will be summarily executed"
next they will want to regulate ejaculations as a form of propulsion or in some cases more than others threatening with a blunt instrument.
thanks for the chuckle.

the other day i went to buy a jackknife at a local store and although it was wrapped in that hard plastic molded casing(they should make the space shuttle out of that stuff) they had to put it in a dangerous goods bag for me to transport to the front of the store. the next day i am in the same store and there is a guy walking around the store with an axe over his shoulder, i near pissed my pants laughing.

By CWI555

Date 05-29-2009 22:42

article 163.3.2a.... I'll have to remember that one.
btw, bat feces is already on the list by it's chemical name.
I believe i will write an article utilizing the chemical names of common compounds and see how it reads.
Then again, I better be careful. The deputy might have more than one bullet in his pistol.

By darren

Date 05-30-2009 09:43 Edited 05-30-2009 09:47

if he does .... duck twice

this is so much fun wahoo freedom.