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Rocket powered Bell X-1

Old 12-31-2003, 02:56 PM
  #1  
dannost
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Default Rocket powered Bell X-1

I have just started construction on a Bell X-1. I've drawn the plans in Autocad using a 3-view I found on the internet as a guide.
The model will have a 36" wingspan (just slightly larger than scale) with a NACA 2408 airfoil.
Power will be a reloadable rocket engine with an onboard igniter, so I can drop the plane from the air and then fire it.

I will post some pictures as I go if anyone is interested.

Thanks to Mac Hodges for some good advice.
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Old 01-09-2004, 09:46 AM
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dannost
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Default RE: Rocket powered Bell X-1

Construction is coming along. The toughest part is deciding how to make the tail.
Since the stab is up high on the fin, I don't get any strength from the fuselage.
I've decided to use some carbon fiber to help hold the stab to the fin, then
sheet the whole thing at once.

I wish I had a lathe to make the nose. Anyone ever tried using a drill somehow
as a make-shift lathe?
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Old 01-09-2004, 11:16 AM
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DocYates
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Default RE: Rocket powered Bell X-1

I have tried attaching a block of balsa to a long bolt and then to my drill press (variable speed). It worked pretty well. I then sanded with fine sand paper, filled the hole and "viola!", it worked. Good luck. Nice project. You gonna make the plans available?
Tommy
Old 01-09-2004, 12:13 PM
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dannost
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Default RE: Rocket powered Bell X-1

I'm happy to make the plans available. I should probably fly it first though to work the bugs out
Old 01-09-2004, 12:26 PM
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Default RE: Rocket powered Bell X-1

I used a drill as a lathe to make a nose cone for a large rocket. It worked well. I did the same as DocYates and put a bolt in the block of balsa. I then mounted my drill in my vise and used sand paper to shape the cone. It turned out nice.
Old 01-09-2004, 12:52 PM
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Default RE: Rocket powered Bell X-1

I have had a hard time locating a motor for the plane. Single use motors almost all have an ejection
stage built in to fire a parachute in a normal rocket. The only motor I found that didn't have that is
made for rocket boosted gliders. The motor is an E9, which would not have enough boost.
The ideal motor is a reloadable motor. The main company that makes them, Aerotech, had a fire
and is not producing very many now. I was finally able to find one, but I'm still waiting for it to arrive.

It is an Aerotech RMS 29/40-120. This takes a wide variety of reloadable kits, so I can experiment
to determine which one is best. With the reloadable ones, you can just leave out the ejection load
when you load it up.

They make another system which has loads specifically for gliders, but that was impossible to find.

Ignition will be with a small momentary switch operated by a servo. I'm hoping to use the receiver battery
for the power, but I have to experiment to see if the voltage is enough. The specs call for a 12 volt battery.
Mac Hodges told me he uses a custom igniter that you put together yourself and he operates it
from a 6 volt receiver battery.
Old 01-09-2004, 12:59 PM
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Default RE: Rocket powered Bell X-1

You might consider looking around your area for a local model rocket club. Some of the people that build the standard model rockets also build rocket powered r/c planes and they might be able to help you out a little on the engines.
Old 01-09-2004, 02:12 PM
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Rick Lindsey
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Default RE: Rocket powered Bell X-1

I used to be in the High-Power Rocket scene (many moons ago), and at that time there weren't very many long-burning reload kits available. The 29/40-120 will basically allow you to use from 1 to 3 40newton-second slugs in a 29mm case, so they will all have the same burn time. There should be black-jack ("long" burning), blue-thunder (short burn) and I forget what the medium burn formula is called. I had their 38mm reload kit, and used the blackjack reloads almost exclusively, since I liked longer burning motors. The longest burn for the 38mm reload kit was still under 3 seconds, though. It's a shame you can't get their Glider Motor (32mm, I think) anymore.

Aerotech made a G12 single for gliders(32mm), but the G20 single-use motor burns for about 5 seconds. It was my favorite 29mm motor. They also made an E6, which would be cool for a smaller rocket-powered plane.
Old 01-13-2004, 08:44 PM
  #9  
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Default RE: Rocket powered Bell X-1

Construction is coming along well. I finally got my rocket motor casing and loads. The casing is longer than the dimensions I was given, so I may have to rework the vertical piece that braces the fin.

As I look at the size of the plane the wing doesn't seem very large. I made it just slightly larger than scale, but I guess this plane was made for speed and not glide time.

Do you scratch builders try to calculate weight and wing loading when you design? How?
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Old 01-13-2004, 10:35 PM
  #10  
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Default RE: Rocket powered Bell X-1

ORIGINAL: dannost

Do you scratch builders try to calculate weight and wing loading when you design? How?
I don't have a scientific method of pre-calculating weight. For me it's based on experience and usually I'm in the ball park or lighter than what I expected.
Old 01-14-2004, 10:34 PM
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Chevelle
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Default RE: Rocket powered Bell X-1

Just a couple of tips. (Great project by the way.)

Don't use the receiver battery for the igniter. Igniters are nicrom wire and draw a lot of current to get hot. Your reciever battery is not made for that and drawing down on it right at the critial point of ignition could be a bad thing.

Rocket motors burn REAL fast. I don't now how you could possibly control the plane not to mention the G forces on the plane! I would assume that even a slow burn motor would be too fast.

Have you considered CO2? You wouldn't have the igniter problem, the release is much more regulated, and CO2 cartidges are easily reloaded.

Also, I haven't checked lately but aren't rockets and other similar devices against AMA guidlines?

Like I said, great project. Good luck.
Old 01-16-2004, 12:07 PM
  #12  
Johng
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Default RE: Rocket powered Bell X-1

This has already been done at some of the biggest sanctioned meets in the country, by Mac Hodges. The plane drops, the pilot gets it wings level and nose up, and fires. Seems like he has good control to me, as a burn usually takes 2-4 seconds. That's plenty of time if you are paying attention. If there was a problem, we'd probably have heard about it. Seems rocket launched aircraft are legal, though launching an unguided rocket from an airplane wouldn't be.

From the safety code:

"7) I will not operate models with pyrotechnics (any device that explodes, burns, or propels a projectile of any kind) including, but not limited to, rockets, explosive bombs dropped from
models, smoke bombs, all explosive gases (such as hydrogen filled balloons), ground mounted devices launching a projectile. The only exceptions permitted are rockets flown in
accordance with the National Model Rocketry Safety Code or those permanently attached (as per JATO use); also those items authorized for Air Show Team use as defined by AST
Advisory Committee (document available fromAMA HQ). In any case, models using rocket motors as a primary means of propulsion are limited to a maximum weight of 3.3 pounds
and a G series motor.
A model aircraft is defined as a non-human-carrying device capable of sustained flight in the atmosphere not exceeding the limitations established in this
Code, exclusively for recreation, sport, and/or competition activities. The operators of radio control model aircraft shall control the aircraft from the ground and maintain
unenhanced visual contact with the aircraft throughout the entire flight operation. No aircraft shall be equipped with devices that would allow for autonomous flight."
The question this raised in my mind is for when I get my A-10 flying. If I were to drop a rocket boosted anti-tank missile and it had RC control it should be no problem, right? It wouldn't impact under power or anything. It would essentially glide down after a short boost.
Old 01-16-2004, 03:30 PM
  #13  
dannost
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Default RE: Rocket powered Bell X-1

It seems to me that that is the same thing I am doing, as long as you can control the missile (which seems difficult without wings/ailerons etc)

Thanks for posting the rule also. It seems clear that as long as I am under 3.3 lbs and use a G motor or less I am OK.
Old 01-16-2004, 03:55 PM
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Rick Lindsey
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Default RE: Rocket powered Bell X-1

ORIGINAL: Chevelle
Don't use the receiver battery for the igniter. Igniters are nicrom wire and draw a lot of current to get hot. Your reciever battery is not made for that and drawing down on it right at the critial point of ignition could be a bad thing.
While I agree that using your receiver battery might not be the best idea, not all ignitors are nichrome wire. Certainly Estes ignitors are, and I think there might be some nichrome in a copperhead too. Flash-bulb ignitors, on the other hand, are notoriously easy to set off (so easy, in fact, that people would worry about static electricity setting them off).

I can't remember what kind of battery was used to set off the flashbulbs in my ejection charges, but I think i suspect that a 4.8v receiver battery would have plenty of oomph to kick it off.

-Rick
Old 01-16-2004, 04:02 PM
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Default RE: Rocket powered Bell X-1

I'm talking about the old AGM-65 maverick missile. I'd probably just paint one fin black - and possible keel weighted - so the pilot could keep it oriented and fly it in.

Old 01-16-2004, 04:54 PM
  #16  
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Default RE: Rocket powered Bell X-1

This project is SWEEEEEEEEET!!! I've always wanted to do this one.

Question: What kind of plane are you dropping it from? A B-52? What happens when this baby zips out of sight before you can turn it? Remember, rockets ar fast. I would probably launch and then point it straight up on that first try to see how fast it goes. What length of burn time are you predicting?

Remember to video tape this so we can all see it fly. Okay?

the model is looking great. GOOD LUCK!
Old 01-16-2004, 05:15 PM
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Johng
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Default RE: Rocket powered Bell X-1

I've seen this done by Mac Hodges.. It's impressive no doubt but lets not get carried away with how fast it goes or if it's gonna go out of sight. THe X-1 drops from a B-29 and glides down to 50-75 feet high in front of the crowd. THen the pilot pulls the nose up and fires the motor. The motor burns for a few seconds, but less than a second at high thrust. This thing is large & heavy, even for an E motor so its not like it disappears. It's easy to track. He does fly a gradual pull up under power so it ends up a few hundred feet high. With the small wings & high wing loading, it does come down pretty fast, but with a reasonably flat glide. Here's a shot I took last time it flew at my field, for inspiration:
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Old 01-17-2004, 04:26 PM
  #18  
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Default RE: Rocket powered Bell X-1

Thanks for the pic. I will post pics and a video when it flies.

I am dropping it from a trainer to start. A friend has a setup already that he used for gliders. So far I haven't talked anyone
in my club into building a B-29.

A guy in my club did some math and was guessing that it would go about 80 mph or so on boost. Mac Hodges said that their plane that was just slightly larger
than mine would shoot almost out of sight with a G64 motor. I'm planning on using an F40. First flight will be an E23 for testing. Most of the motors
burn for about 2 seconds. A few will burn for close to 4 seconds but with less boost.
Old 01-17-2004, 04:27 PM
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Default RE: Rocket powered Bell X-1

Ive watched Mac and his friend(who flys the X-1) but i cant rember his name on the 03 topgun video do this. The X-1 Is big. Ide guess 50 to 60" long and the guy handles it like a pro as usual. The other impressive thing is to see a monster r/c B-29 doing almost flat spins and low inverted passes. The way i understand it , Mac has been doing this for along time. Hes built at least 3 i think. Ive been tempted myself to imatate a rocket glider like this to. Glad to see your taking on the project. . There is a website with some pics and info somewhere but i cannot locate it. It has some more info about Mac's projects. Your ship is looking. Thanks for sharing this thread and i will be looking to learn from your experiance. When i scratch up a plane i can only use my experiance in past projects with simular materials and systems to estimate weight of the finished plane. The more i build the better i get. But there are so many varibles sometime i just build it, I know what my intended power sys i going to weigh so depending on the strength needed and the materials used. Sometimes i have to change power sys or parts of sys to achieve desired finished weight. But thats why its so much fun. Makes me think harder. Sometimes i cant get the desired weight and it becomes a wall hanger. Thats usually when i build it just to dang tail heavy and wing loading is to high for the particular design and flight characteristics after the plane gets on the balance. agin, thanks for sharing your X-1 project.
Old 01-22-2004, 12:23 PM
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Default RE: Rocket powered Bell X-1

Sheeting of the fuse is almost done. Control surfaces, servos and linkages are done.
I am waiting to receive my igniters from rocketflite before I figure out the ignition system.
It looks like I might be lucky with balancing. Using a standard receiver battery it balanced out
pretty close with it all the way in the nose. I may need a little nose weight, so I might try using
a standard 9v battery separately for the ignition.

I wanted to use the trainer switch for the ignition, so it can never stay in the on position, however
I can't find anything in the manual for my JR 8103 that allows me to assign a channel to it. I may be able
to use an auxiliary channel and put an alarm on it though.
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Old 01-22-2004, 10:09 PM
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Johng
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Default Warning; Danger Danger Will Robinson!

Looks like good construction, but the length of that elevator pushrod has me nervous. That's got to be a 25" run. Is that just a wire pushrod as it seems? I hope not. That looks like it has too much freedom to flex, which could be a recipe for flutter under power at high speed. With the horizontal already mounted to the vertical, which is less sturdy than a fuse mounted stab this could be a weak point. Not trying to pick on you, just a warning.

At the very least, I would use a Dave Brown fiberglass tubular pushrod or a CF pushrod on a run that long. Or better, move the servo back as far as practical so the pushrod can be shorter. It won't matter if you save on nose weight when the elevator flutters off. Hope that's not to pushy, but I had to say something.
Old 01-23-2004, 09:22 AM
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dannost
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Default RE: Warning; Danger Danger Will Robinson!

I thought the same thing. Since the picture was taken, I routed the pushrod inside a plastic tube with nyrod spacers the entire length inside the fuse and routed through the formers.
It feels pretty solid, I doubt flutter will be a problem. If I try pushing a lot of up elevator while the rocket is firing
and the plane is under full thrust, that might cause some buckle, but that wouldn't be a very good idea anyway.

Thanks for the concern. Being my first scratch build, I appreciate it.
Old 01-26-2004, 12:25 AM
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Default RE: Warning; Danger Danger Will Robinson!

dannost, the X-1 looks great.
I have built a number of rocket powered gliders, so I thought Id chip in with a couple of things.
All of mine were ground launch, so things may be a little different, but theyll still be close.
A "G" size motor will be the one youre after, specifically a G40. This will give about 40N of thrust for about 4 sec. Asuming that youre X-1 weighs in at about 1kg youll get around a 4G accelleration for about 3 sec. the last sec the thrust tapers slightly.
Initially I was worried about the amount of thrust, starting out with Ds and Es, but theres never enough impulse to really get htem going.
On launch I would recommend launching with the X-1 approaching you, otherwise it will dot out and you will loose orientation.
As far as the motors having the ejection charge, you can easily remove it, then fill the area of the ejection charge with 5 min epoxy. This gives a wide range of motors.
Be careful of any motor with a high initial impulse, gliders dont like them. I tried a G125 in an effort to get some more speed, big mistake. THe aero loads virtually tore the ship apart.
With reguard to flutter, if youre staying under a G size, you wont have a problem, the drag of the glider is much higher than a rocket, and as such they dont take off the the same extent.
Good luck, the X-1 looks fantastic, any questions dont hesitate to ask.
Old 01-27-2004, 10:37 AM
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Default RE: Bell X-1

I tried the drill press for a lathe. I actually glued a hardwood dowel in the center all the way through
then chucked it into the drill press. Then I just sanded the dowel down to a point so it gave me a nice
hard point. Worked great, but a lot of sanding.

The ignition switch is in, operated with a servo as seen in the pic. I also made an access hatch
in the aft end in order to hook up the igniter. I soldered a deans micro plug to a lead wire, then I
will solder the matching plug on each igniter (before I dip it in the chemical, just in case). Now I need some good weather
so I can do some tests with the igniters to make sure the system works.

Sheeting is done also. Now I have to cover.
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Old 02-26-2004, 12:44 AM
  #25  
dannost
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Default RE: Bell X-1

The plane is ready for flight testing. I'm hoping to get to try it this weekend.
I put a 600mah receiver battery in front, and a 9v battery all the way in the nose. This balanced it out almost
perfect, just need a little bit of weight in the nose. All up weight, with loaded motor, is 29 ounces. I was happy to
have it under 2lbs.

I made up some of the ignitors from rocketflite and tested it using a 9V battery and it worked great.
I did not want to waste a motor by testing though, so we will see what happens.

I still need to make a few more decals. Does anyone know where I can find the "Glamourous Glennis" and Bell Aircraft
graphics? I bought a plastic kit, but the scale is so small I can't get a good scan to reproduce.

Here are a few pics.
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