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piggyback launch

Old 02-08-2010, 12:18 PM
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snip
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Default piggyback launch

I'm looking for some advice on cradle launching an AIRTRONICS OLYMPIC II(100") glider from a BUD NOSEN 104" 7AC CHAMP. I built the cradle and release from my own design. It is a single pin system activated with the auxilary switch on the Champ. It works quite freely and is very secure. We added two wing stand offs to keep the glider stable during take-off and climbing. The CG on the glider is directly over the CG on the Champ. The total weight off the two units is approx. 16lb. Power is a G26 gas, with a 14x6 prop. We are totaly in the dark about any of this, and would appreciate any suggestions and advice before we decide to destroy two planes at once instead of our usual one at a time. Is there any web site or link that may shed some light on this project.
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Old 02-08-2010, 12:27 PM
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snip
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Default RE: piggyback launch

I forgot to add the picture of the whole package
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Old 02-08-2010, 12:35 PM
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rafeeki
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Default RE: piggyback launch

Sorry that I dont have any inteligent suggestions for you but I thought your note on not wanting to destroy two planes at once instead of one at a time as we normaly do was hilarious) thanks for the laugh.
Old 02-08-2010, 12:49 PM
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soarrich
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Default RE: piggyback launch

Fly it! You won't even know it's on the Cub.

If you own both planes, make sure you fly the one you have the radio for. I saw a guy lose a $4000 tow plane because he owned both and was more interested in the sailplane's test flight.
Old 02-08-2010, 12:57 PM
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Default RE: piggyback launch

the only issue I see is I think your plane/motor is underpropped. I'd definately be looking at a 16 x 6 if not bigger
Old 02-08-2010, 01:10 PM
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Default RE: piggyback launch

I miss informed, the prop we are running is a 16x8. Neither plane has flown yet, and we will be putting lots of time on both before we hook them up. We are just not sure of the pitfalls and problems we can run into while they are flying as one.
Old 02-08-2010, 01:14 PM
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qldviking
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Default RE: piggyback launch

that sounds a lot better, check your original post, you stated it was a 14 x 6.
Old 02-08-2010, 02:35 PM
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Tinkrerpilot
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Default RE: piggyback launch

Like the guys say, "Fly It". Get comfortable with the Champ before tossing the glider on it.

There have have been many discussions on this subject. Do a seaarch on the glider cradle. Key words piggyback launcher or glider cradle should bring up your results.

Most of all, have fun with it.

tink
Old 02-08-2010, 02:50 PM
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Default RE: piggyback launch

I am no expert..however I have launched a few gliders piggy back, and broken one ! so take that for what its worth. It appears you are using a solid belly release instead of bungies? That I like the looks of. One of my dislikes on my rig is the bungee setup. The wing posts will help as well. Everything I could see looks like you are heading the right direction. I would like to see some closer views of the actual clamp/release area of your setup.

By the way if you have flown any biplanes you know that they have a different FEEL on the sticks than a monoplane. Expect it to fly somewhat more like a biplane with it all together..thats my opinion. I do believe that your tug should have no problem with the glider interfering with control (as mentioned above) but it will be different.

I know this sounds crazy but the first time you fly it with all that gear stacked up..it might be a bit intimidating. My plane sure made me nervous the first time.. I used a giant scale stinger that had been modified into a stick..its not very forgiving or stable as tugs go..so I will probably adapt my Nosen trainer into a tug once I get it flown a few times.

Either way have fun and keep us informed... I like what I see! Oh, and cool to see any Nosen stuff being used !
Old 02-08-2010, 06:11 PM
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iflytailies
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Default RE: piggyback launch

there is not a whole lot to this. Just don't climb to steep. Before releasing, let the glider pilot know. The tow pilot should go into a slight dive and throttle down, then release. Here is how we have done it:

http://www.youtube.com/watch?v=FRUAF2kG28k
Old 02-08-2010, 07:08 PM
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pmw
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Default RE: piggyback launch

Snip,

A few years ago I did almost exactly what you're planning. I cradle launched a Bird of Time from a Nosen Champ. Here's what I found. The ailerons were almost non-functional trying to turn the Champ. Rudder turns were no problem. The speed to keep the planes airborn was too much for the B of Time. At release, the glider would do a immediate snap loop. It was so violent that the 1/4" steel rod wing joiner actually bent several degrees. How the wings survived is beyond me. We tried several launches by actually stalling the Champ, but it only caused the glider to do a slower loop. This was launching the glider with full down elevator. I suspect it was an airflow problem between the two wings. Go for it, but just be prepared for weird things to happen at release. I finally gave up before folding the glider wings and went back to the Hi Start.

Paul
Old 02-08-2010, 08:10 PM
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OzMo
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Default RE: piggyback launch

Did a few launches this summer from the cradle. Here are my "tips" :
Oversized controls or at least hefty throws on the tug won't hurt. STIFF control rods etc are a good idea on the tug.
CG of tug and glider should match.
A SLIGHT down incedince on the glider.
Observe your tugs time to actually slow down to lowest idle speed. Mine takes 30 seconds or more. This is when you release, at the slowest speed the tug can handle. Glider should NOT have any control input until clear of the tug.
Glider has to be in trim BEFORE going on the tug. Don't ask me about this one[:@]

Once you get used to these things the fun will never end. Very high launch altitudes can be obtained, but do the first ones where you can see both planes well.

Next adventure towing???
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Old 02-08-2010, 09:53 PM
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Default RE: piggyback launch

Guys
I really appreciate all the advice. these points are all pretty much the concerns we have, and hope we are addressing them. The speed is a concern, as this could be a problem for the integrity of the glider wing. Hopefully the Champ will have a fairly slow take-off and climb out speed. I too have folded a 1/4" steel joining rod on a Dynaflite Butterfly with a too quick dive recovery. Looked like a dying swan falling from the sky. Saved the plane though, with no damage to the wings. As of now the incidences are parallel. Any idea how much down we should set the glider at? The glider has been trimmed by hand launching and seems to be quite stable and controlable. All this advice is very helpful and appreciated. We need all we can get.
Old 02-08-2010, 10:19 PM
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rafeeki
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Default RE: piggyback launch

Excuse me gents but isnt t beter to be using a 4 stroke engine on the mother ship which will make it fly slower hence less stress on the glider wings anda less abrupt glider release?
Old 02-08-2010, 11:56 PM
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Tall Paul
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Default RE: piggyback launch

I've launched a few gliders, and found it's not that big a deal.
The oddest situation was one of the first flights with no wing supports to keep the glider from banking independently of the carrier plane when turning.
I had one plane that wouldn't fly off when released, but that was fixed by adding some incidence to -that- airplane.. the Cutlass.
The Gentle Ladys have always lifted off on release.
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Old 02-09-2010, 02:41 PM
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pmw
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Default RE: piggyback launch

Tall Paul is right about the lack of wing supports being an issue. I found the long wings of the Bird of Time with the polyhedral allowed the glider to roll left and right while attached to the cradle. The glider would actually bank the launch plane. We had to keep the maneuvering and speed of the launch plane to a minimum just to keep everything going in a staight line. I wasn't willing to cut into the covering of the launch plane to add wing supports, but they were definitely needed. At least we proved the strength and integrity of the launch cradle. It was a wild ride to launch altitude!

Paul
Old 02-09-2010, 03:33 PM
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Default RE: piggyback launch

Done it dozens of times. Make sure the glider pilot DOUBLE CHECKS full control before lift off, I saw one drop the glider only to find that nobody bothered to turn the reciever power on!

Make sure the incidence between the glider wing and the tug wing is 0 or very slightly negative at Oz said, otherwise the glider will try to yank the tug into the air while the wing is still stalled.
Old 02-09-2010, 07:03 PM
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Default RE: piggyback launch

a 4 stroke to fly slower? thats what a throttle is for. I am in the process of building a giant 12" telemaster for my large gliders, and it will be powered by a 48cc twin gasser. It will be set up for cradle mainly, though I am toying with the idea of towing too with a retractable towline. we use to piggy back with an 8' telemaster and had no issues as such with the gliders wanting to turn etc, we had the cradle set to hold the gliders with about 1* of down, we had 2 rubber coated dowel at the back to hold wings against and we used 3/16 shockcord to hold the plane down that was anchored from behind so as to hold the glider firmly. I will be using the same set up again on this telemaster. With judicious throttle use we have yet to have a glider move on the cradle. Sadly the *' tele is no more, a failed clevis on the elevator ended up with the tele trying to fly through trees, which left little to rebuild.
Old 02-09-2010, 10:42 PM
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Default RE: piggyback launch

Yes a 4 stroke will allow u to fly slower as it can swing a larger prop that can develope enough thrust at a slower speed to keep your craft afloat. You cannot develope the same thrust with a 2 stroke.
Old 02-10-2010, 12:38 AM
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Default RE: piggyback launch

Two stroke, four stroke, throttle control? I just use rate of climb to regulate speed. Full throttle!! One on top and one on the towline.....
Old 02-10-2010, 05:37 AM
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marc 540
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Default RE: piggyback launch

ORIGINAL: rafeeki

Yes a 4 stroke will allow u to fly slower as it can swing a larger prop that can develope enough thrust at a slower speed to keep your craft afloat. You cannot develope the same thrust with a 2 stroke.
[sm=spinnyeyes.gif] This make's no sense whatsoever!!

Marc
Old 02-10-2010, 07:42 PM
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Default RE: piggyback launch


ORIGINAL: marc 540

ORIGINAL: rafeeki

Yes a 4 stroke will allow u to fly slower as it can swing a larger prop that can develope enough thrust at a slower speed to keep your craft afloat. You cannot develope the same thrust with a 2 stroke.
[sm=spinnyeyes.gif] This make's no sense whatsoever!!

Marc
Ok, here is what I think he is saying.
A four stroke can throw a larger dia prop. SO at low speeds or idle that big prop acts like a brake (it has more drag). I don't think it makes a lot of difference in this application. I run an OS 91FX on my 2 meter span Telemonster. 13/8 prop seems fine so far. Big draggy tugs will slow down anyway.
Old 02-14-2010, 01:03 PM
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Default RE: piggyback launch

Tug wing incidence 0 degrees.........Glider wing incidence -1 degree
Old 04-19-2010, 10:42 PM
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opwan
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Default RE: piggyback launch

Uh those "sailplanes" you have pictured are not even close to the BOT. 118in wingspane might have a little different effect! The Bird of Time is a though Bird to tame anyway, I wouldn't even think about a cradle or tow line for mine, it's been converted to electric anyway, but sometimes it can be a wolf in sheeps clothing. The Bird is not the average glider it takes a very skilled pilot just to keep it on a leash.
ORIGINAL: Tall Paul

I've launched a few gliders, and found it's not that big a deal.
The oddest situation was one of the first flights with no wing supports to keep the glider from banking independently of the carrier plane when turning.
I had one plane that wouldn't fly off when released, but that was fixed by adding some incidence to -that- airplane.. the Cutlass.
The Gentle Ladys have always lifted off on release.

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