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Forbidden Subject?? - 4/13/2002 10:47:54 PM   
Woodpile



Posts: 212
Joined: 1/12/2002
From: Barnegat, NJ, USA
Status: offline 		Hello All,

I have a question about powering a glider and hopefully can be steered in the right direction.

Let's begin at the beginning... I have a fair amount of modeling (building) experience and am a tinkerer (because I can not leave well enough alone!) I started in RC about 2 months ago, but I'm having trouble flying my plane. I think it's just too much for me at this point, so what I thought was to build a glider to get some stick time, and then move back into powered flight. It is my impression that gliders and sailplanes move a little slower, but my problem is that I really don't want ot make/buy a hi-start and a winch is definately out of the question. The first flights would be hand launched for trim and adjustments, but how to gain some manuvering room? My thoughts turned to JATO, as my 9 year old daughter has discovered model rocketry. It seems like a perfect, renewable altitude maker, but I would like to know if anyone has experience in this area, specifically, the design/beefing up of planes for the sudden acceleration. Is it comparable to a hi-start or winch? Should I add supports to the wings? What is the best launch angle? How much elevator can these planes take with the engine burning? Obviously that one will depend greatly on the exact model I build, but you can see what I'm getting at. With a standard two-meter plane, am I likely to fly the thing out of sight before the engine stops? I would start off with the smaller engines at first, but it's that great unknown first flight that I'm worried about... The field I'm planning on using is about 400' x 300'.

Any advice would be greatly appreciated as it will calm some jitters before the first flight.

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Forbidden Subject?? - 4/14/2002 1:46:03 AM   
seafury_fb11



Posts: 236
Joined: 2/22/2002
From: Los Angeles
Status: offline 		Woodpile,
Well.. the Germans did it so we know its possible. However the AMA has rules against that sort of thing. If you are out in the middle of nowhere and you insist on launching your plane that way, I would just try it. Those rockets are really light. A plane on the other hand, is quite a bit heavier - I doubt seriously that your plane would go out of site. You might rip the wings off, but it probably wouldn't go out of site.

Russ.

< Message edited by seafury_fb11 -- Apr 15 2002 2:14PM >


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Forbidden Subject?? - 4/14/2002 3:07:27 AM   
Wayne22



Posts: 4513
Joined: 4/10/2002
From: Edmonton, AB, CANADA
Status: offline 		I don't think I would recommend that route. The hand launching part is okay. The rocket powered part would cause concerns...

Do you have any hills or slopes you can use? tall buildings..?

If not, a safer, easier, albeit more expensive route would be to get a 2 meter electric powered glider.. Something like a goldberg electra, with a servo powered on/off switch, some cheap tamiya 6 cell packs and you can fly all day....

Or, if you are into self abuse, you can get one of those annoying little cox engines and stick it on the nose of pretty much anything. ...

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Forbidden Subject?? - 4/14/2002 3:09:21 AM   
MikeL



Posts: 2543
Joined: 3/8/2002
From: Bloomington, MN, USA
Status: offline 		A much more reasonable and feasible solution would be to put a power pod (either electric or glow) on the glider. These are inexpensive, easy to use, and safe. A rocket might seem like a straight ahead solution, but when you've got a bit more experience with both rockets and RC, you'll understand that it's not all that straight ahead.

Other alternatives include electric gliders, or something like a Dynaflite Butterfly.

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Forbidden Subject?? - 4/14/2002 4:27:34 AM   
Ollie


 

Posts: 958
Joined: 12/8/2001
From: Punta Gorda, FL
Status: offline 		There are R/C sailplane clubs in your area that will provide the launching equipment and flying sites suitable for sailplanes. My guess is that they would welcome you as a guest flier and allow you to launch with their equipment if you are an AMA member. The chances are good that they would give you free flight instruction if you join. You will become a competent flier about ten times quicker in a glider club environment than going it alone.

NORTH JERSEY SOARING SOCIETY STEVEN H LUCKE 1100 PARSIPPANY BLVD APT #14 PARSIPPANY NJ 07054-1851

SOUTH JERSEY SILENT FLYERS JOHN W JENKS 39 CARLTON AVE MARLTON NJ 08053-1901

BERGEN COUNTY SILENT FLYERS BEN BENDIT 233 ELMWOOD AVE GLEN ROCK NJ 07452

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Regards, Ollie

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Forbidden Subject?? - 4/15/2002 3:06:41 AM   
greg-RCU



Posts: 124
Joined: 12/5/2001
From: Gibsons, B.C.
Status: offline 		WoodPile, Those rocket motors are three to four dollars a pop (and I do mean pop).

To launch a nice light floater type glider that flies nice and slow you would have to reinforce it along the thrust line and couple that to the spar. i.e. Add lots of weight which equals speed which defeats your initial idea.

I have a field about the size of yours and I eventualy built a small HiStart or Upstart from 30' of 5/16" rubber tubing (1/16" wall) and 120' of kite string and a dog stake. Total cost was about $40 or 10-15 of your rocket launches. I easily did 20 launches the first afternoon I had it. It requires less than 300' of field streached out and launches the plane to 150'. That's good for 90seconds of stick time in dead air.

Here's an even cheaper idea. Get an interested teenager to tow it for you! Maybe your daughter could pull it with her bike. I did this for a couple weeks while scouting out a source for the rubber. It works great in a slight breeze but is a real challenge if there is no wind at all. The more wind you have the more line you can give it.

If you really like to tinker build a bike powered winch! Theres a pic on the 3rd page of the Show and tell thread of this forum.

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Forbidden Subject?? - 4/15/2002 5:39:48 AM   
Terror Dactyl



Posts: 392
Joined: 4/9/2002
From: Jurrasic Park, TX,
Status: offline 		Woody, as a food for thought, one possible route is a Zagi. I say that with this reservation, if you can keep a plane in the air and get it to turn when you want it to then your ready.

The premise is that you need stick time and you need practice on landing. this is a great plane to be able to practice the landings as it is nearly unbreakeable.

I have a 400X and it will do 15min at full throttle.

Here is a little side benefit:
The new guys join in with the others of us for some full contact combat (DONT FORGET THAT THESE BIRDS ARE UNBREAKABLE) and their stick skills progress much quicker in this format.

Take care Jim

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Forbidden Subject?? - 4/15/2002 8:25:00 AM   
KeithK


 

Posts: 16
Joined: 2/15/2002
From: COLORADO SPRINGS, CO, USA
Status: offline 		Estes made some RC boost gliders, some worked OK some didn't. The Sweet-V was probably their best and is still available but you may have to look around. Competition gliders now weigh 1/2 (about 7 ounces) what the Estes gliders weigh. For me it is a novelty, I much prefer my Omega motor glider.



Keith

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Forbidden Subject?? - 4/15/2002 11:02:05 AM   
bjaffee



Posts: 99
Joined: 1/3/2002
From: Calabasas, CA, USA
Status: offline 		I don't believe there are any AMA rules about rocket boost takeoffs. I think the AMA just doesn't like it if the rocket is going to be released from the plane, like a missle.

In addition to the Estes models Keith mentioned, there are some more "serious" (IMO) rocket kits that have been available. One that comes to mind is the Aerotech Pheonix. When I say "serious" I mean that it didn't just use a dinky Estes rocket motor...it used a big aluminum clad rocket motor made by Aerotech.

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Forbidden Subject?? - 4/15/2002 7:11:28 PM   
seafury_fb11



Posts: 236
Joined: 2/22/2002
From: Los Angeles
Status: offline 		Here is rule 9 from the 2002 AMA Safety Code-

[QUOTE]Rule 9:
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 exception 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 from AMA 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. Note: A model aircraft is defined as an aircraft with or without engine, not able to carry a human being.[/QUOTE]

Sounds like it's permissable as long as the plane is not heavier that 3.3 pounds.

Russ.


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Forbidden Subject?? - 4/17/2002 11:43:59 PM   
mucksmear



Posts: 195
Joined: 2/26/2002
From: Berkeley, CA,
Status: offline 		Please consider what you are going to do if your model crashes while the rocket motor is still burning. Suggest you use a speed 400 electric (or .049 glow) power pod on a 2 meter glider.

I had some succesfull flights with a slope soarer equiped with a pod designed to hold 2 standard sized Estes rocket motors (A thu C size) and an alternate one designed to hold a single D motor (the 2 motors in the dual motor pod were fired one at a time).

Both worked like a charm and gave tremendous acceleration (small 44" slope soarer). They would not give you much aceleration on a 2 meter floater however.

Then one day, I had an accident where one motor began to burn from the opposite end (thes situation was a direct result of my dual motor pod design). The resulting fireball burned throught the sheeting on the top of the wing, fried my aileron servo, and released the wing from the fuselage, which was subsequently hanging below the wings by the servo wires as the now dissassembled model spiraled Earthwards, with dense white smoke pouring out of the top. Fortunately I did not burn down the entire Golden Gate National Recreation Area.

I'm wiser now.

-E

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Forbidden Subject?? - 4/18/2002 4:08:24 AM   
Terror Dactyl



Posts: 392
Joined: 4/9/2002
From: Jurrasic Park, TX,
Status: offline 		Good thought, that is why I like the Zagi 400X (speed 400 with a 1700mha batery for 15 mins of fly time).

Take care Jim

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       Post #: 12

Thnks - 4/20/2002 5:29:10 PM   
Woodpile



Posts: 212
Joined: 1/12/2002
From: Barnegat, NJ, USA
Status: offline 		My thanks to all who responded. You have givien me much to think about, although it sounded like a good idea at the time.

Mucksmear, I did not think about a crash before the engines stopped burning. That is a sobering thought...

Perhaps when I get some more stick time under my belt, I'll try it with a sort of scale U2, but until them I have my eyes on something more conventioinal.

Thanks again!

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There's a fine line between hobby and MENTAL ILLNESS.

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       Post #: 13

Forbidden Subject?? - 6/5/2002 9:17:31 AM   
stulwilson


 

Posts: 21
Joined: 5/4/2002
From: Conroe Tx
Status: offline 		As a tinkerer, there are also many SPAD designs out there that can be built on the cheap. you probably already have alot of tools and parts. It doesn't take much to strap a battery pack, esc motor, rx, and servos to a peice of coroplast or foam. some arrow shafts, or carbon fibre spars from your hobby shop, and some cable ties are about all it takes to make a cheap fun plane. I bought a viper twin and demolished it. So, I took the parts, and started making my own wings from designs I found. I have been having tons of fun. I built 8 planes, and when I come up with a better design idea, or have a big crash, I rip the electronics out, and make another one. I have a low budget for flying, but I can afford $10-$15 us per fuselage. Electronics, and chargers are the expensive part, but if you go electric, you have to have them anyway. once you have them, the planes are nothing. I actually enjoy a good crash when I try to do aerobatics too close to the ground. I don't cringe anymore. I just look forward to discovering, and eliminating another weakness in my airframe. Just another idea for cheap stick time. good luck.

One pro for the rockets though, just like good ol'e fire-works, they are good for an entertaining show. Just gotta watch where you point those things.

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       Post #: 14

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