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Old Sep 07, 2012, 09:43 PM
kdt
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65 m of mono with single 3.5 mega bungee

Today was a very light day with challenging small thermals. I setup on a new friends field only 15 minutes from my house. The short length mono with the single 3.5m bungee was perfect for the size of field. I spent 4 hours trying different techniques to see what worked for me. I was getting the best launch height starting with launch camber and 2 to 3 second tows. Not up to 90lbs but it is improving. I'm trying to maximize the bungee stretch on zoom. The dreaded parachute pop was heard many times as well as the limp lack of power on the zoom due to leaving it too late.. A bit of a tight rope walk and I'm still pretty wobbley. Great Fun and my right arm is beginning to look like Popeyes..

.I really like this kind of launch!
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Old Sep 08, 2012, 01:48 AM
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Seattle
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I have found that using the Death Match zip start has vastly improved my throwing style. I have small hands (it creeps my wife out) and holding onto the fuse at the leading edge of the wing has always been difficult (sure-laugh away). I've watched a lot of people that I consider to be pretty good at this and most of them wrap some of their fingers around the fuse and use some under the wing spread out to support it. Can't do that.

So I hold the fuse right at the hook (it's in the palm of my hand) and I find that I can hold rather large amounts of tension this way when I lock out my elbow. Just lock the elbow out, walk back as far as you can, and let the arm rotate only at the shoulder like a cricket pitcher throws (do they call him a pitcher? I always fall asleep watching so I never have learned the positions).

Since my hand is at the point where the bungie attaches rather than foward, I'm not having to use a lot of wrist to keep the plane from rotating horizontal so it is in a very nose up atttitude when I throw it with little effort to keep it there. With the amount of tension the zip requires, I've improved throwing the airplane quite a bit. I've not done any throwing using two-man tow on mono so I don't know how this technique would translate.

Anyway.....

We have a SASS Death Match this weekend-folks should come over and check it out. I'll see if I can get a load cel on a Zip and see what tensions we are pulling. With the Death Match, lite and heavy models seem to fair rather equally since all are launching to rather low altitudes. If the air is easy, we shorten the task to make the landing more predominant. If the air turns to crap we make the task longer for more interesting flying (part of Death Match is the heckle factor). Folks seem to really enjoy the challenge and rarely does a lite (or heavy) model dominate due to the various factors that make weight (or lack of it) advantagous.

BK
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Old Sep 08, 2012, 02:31 AM
kdt
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I'm thin wristed

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Originally Posted by belouder View Post
I have found that using the Death Match zip start has vastly improved my throwing style. I have small hands (it creeps my wife out) and holding onto the fuse at the leading edge of the wing has always been difficult (sure-laugh away). I've watched a lot of people that I consider to be pretty good at this and most of them wrap some of their fingers around the fuse and use some under the wing spread out to support it. Can't do that.

So I hold the fuse right at the hook (it's in the palm of my hand) and I find that I can hold rather large amounts of tension this way when I lock out my elbow. Just lock the elbow out, walk back as far as you can, and let the arm rotate only at the shoulder like a cricket pitcher throws (do they call him a pitcher? I always fall asleep watching so I never have learned the positions).

Since my hand is at the point where the bungie attaches rather than foward, I'm not having to use a lot of wrist to keep the plane from rotating horizontal so it is in a very nose up atttitude when I throw it with little effort to keep it there. With the amount of tension the zip requires, I've improved throwing the airplane quite a bit. I've not done any throwing using two-man tow on mono so I don't know how this technique would translate.

Anyway.....

We have a SASS Death Match this weekend-folks should come over and check it out. I'll see if I can get a load cel on a Zip and see what tensions we are pulling. With the Death Match, lite and heavy models seem to fair rather equally since all are launching to rather low altitudes. If the air is easy, we shorten the task to make the landing more predominant. If the air turns to crap we make the task longer for more interesting flying (part of Death Match is the heckle factor). Folks seem to really enjoy the challenge and rarely does a lite (or heavy) model dominate due to the various factors that make weight (or lack of it) advantagous.

BK
Thanks BK. My most difficult part has been holding the model. Today it was my grip that failed before my arm or legs even with the use of a leather glove. My hand is ok but my wrist is as thin as an Alien's . I have tried holding around the nose and around the tow hook but have not gotten the best solution as yet. I know Arend prefers the nose and I think Joe likes the tow hook area... Another question Joe

I would very much like to check out your Death Match. This weekend is booked but I would be interested in the next one. Are you gong to continue with them into Fall if the weather stays nice? Where are you posting the contest info? David has told me about the heckle factor.
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Old Sep 15, 2012, 03:20 AM
launch low, fly high
New Zealand, Hawke's Bay, Havelock North
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Originally Posted by kdt View Post
...I think Joe likes the tow hook area... Another question Joe
Yes, I hold at the towhook.


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Originally Posted by kdt View Post
Technique seems to be a very big factor. In France you did very fast zoom launches in reflex with a two man tow that resulted in over 100 meters. Are you using a similar technique with the mega bungee? Some pilots I've seen are getting a lower but faster launch by doing a quick deliberate pop off. This would not be very efficient use of the bungee stretch. Very often you hear the chute pop with the left over tension not utilized by the model on launch. It seems a bit daunting to measure this with so many variables.

What are your ideas on technique in various wind conditions to maximize the height time relationship? How do you measure this? How much does your technique differ with a 2 man tow over a mega bungee for a short tow?
Technique matters... Even with the same start tension, the launch tension/height will definitely show who is throwing with more energy. I've seen this demonstrated many times.

Yes, I got pretty well trained for the quick tow via practice with my bungee. I tend to get about 100m of launch height with a quick tow, whether from a f3j hand tow or from my bungee.

The time/height optimization is not an easy one to sort out. So much of the answer is dependent on what the pilot thinks is the best choice given the conditions (good thermals?, wind?, length of contest?). With the advent of the 1 pt/ 20 cm landing tape, there is a bit less emphasis on the absolute shortest tow. That said, in some conditions a short tow is very much desired (for example, the cup event prelim rounds held prior to the South Africa WC). With the bungee, you have to factor in the energy in the bungee so as to sort out when it is the best time to zoom. With light to no wind, the best time to zoom is only a couple of seconds after the throw if you are going for maximum height. BTW, it does not take much wind to change this. Just a couple m/s of wind and the highest launch results from a zoom at around 50-60 deg up as measured from from the stake location.

BTW, I'll have my bungee with me in Muncie next week. If DW brings his bungee, he and I can do some death-match bungee style competition while practicing for the comp...
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Old Sep 15, 2012, 12:46 PM
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Yes, I hold at the towhook.




Technique matters... Even with the same start tension, the launch tension/height will definitely show who is throwing with more energy. I've seen this demonstrated many times.

Yes, I got pretty well trained for the quick tow via practice with my bungee. I tend to get about 100m of launch height with a quick tow, whether from a f3j hand tow or from my bungee.

The time/height optimization is not an easy one to sort out. So much of the answer is dependent on what the pilot thinks is the best choice given the conditions (good thermals?, wind?, length of contest?). With the advent of the 1 pt/ 20 cm landing tape, there is a bit less emphasis on the absolute shortest tow. That said, in some conditions a short tow is very much desired (for example, the cup event prelim rounds held prior to the South Africa WC). With the bungee, you have to factor in the energy in the bungee so as to sort out when it is the best time to zoom. With light to no wind, the best time to zoom is only a couple of seconds after the throw if you are going for maximum height. BTW, it does not take much wind to change this. Just a couple m/s of wind and the highest launch results from a zoom at around 50-60 deg up as measured from from the stake location.

BTW, I'll have my bungee with me in Muncie next week. If DW brings his bungee, he and I can do some death-match bungee style competition while practicing for the comp...
im just packing my gear right now so ill see if I can take my bungee. I would love to do some head to head comparisons ! Seems like the best way to learn to geet absolutely crushed by better pilots ...

The oversize quote from United Airlines was $200 each way - $400 round trip so im actually going to ship my box ground...it looks like ill get a 4 day delivery for $300 with insurance and real tracking. That takes a bite out of my budget!
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Old Sep 16, 2012, 03:58 PM
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irvine, ca
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They're called bowlers

http://en.wikipedia.org/wiki/Bowling_(cricket)

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Originally Posted by belouder View Post
... and let the arm rotate only at the shoulder like a cricket pitcher throws (do they call him a pitcher? I always fall asleep watching so I never have learned the positions).

BK
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Old Sep 28, 2012, 08:16 PM
Launch high. Fly low.
United States, CA, Lake Elsinore
Joined Aug 2003
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Hi, guys.
So, is there a verdict on a 'standard' death match bungee proposal yet?
I'm sort of holding off on getting another bungee unless I know what to get exactly; they're not that cheap.

Soar!
Jun
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Old Sep 28, 2012, 08:25 PM
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Originally Posted by jcats View Post
Hi, guys.
So, is there a verdict on a 'standard' death match bungee proposal yet?
I'm sort of holding off on getting another bungee unless I know what to get exactly; they're not that cheap.

Soar!
Jun
Thats a good question - Here is my position.

I dont think that you should hold off on your purchase. Even if your bungee does not match say what the SASS club is using the concept is quite close.

Within 4-5 test launches you would probably adjust to another setup once you are familiar with zip starts in general.

This thread was really to facilitate a full (ish) launch height scenario for a larger MOM format and I think its progressing well.

The test bungee shipped a couple days ago - my planes shipped from Chicago yesterday - I should have some reports by the next weekend.

DW
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Old Sep 29, 2012, 10:42 PM
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Seattle
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Dave,
Weather is supposed to be good this week through the weekend. Maybe we can throw together a Death Match for Saturday or Sunday down here?
BK
SASS
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Old Sep 30, 2012, 10:21 AM
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Dave,
Weather is supposed to be good this week through the weekend. Maybe we can throw together a Death Match for Saturday or Sunday down here?
BK
SASS
Im game - my planes arrive from Fedex on Wednesday - and im working locally for the week! I shoudl also have htat est bungee ill bring it down and the club can evaluate that with me.

DW
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Old Oct 05, 2012, 08:51 PM
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The new 25' spec rubber from Marc Mec is in my hot little hands. I am going to rig up some extra stout anchoring system and have a go at 10-15 launches and see what we get out of this.

I am using the same length line as I did with the 2x 25 ' 4 meter bungees

The new stuff is a step down from what JW and my team mate Keith use for sub second J starts and I am hoping to get 200 meters over a 3-4 second tow scenario at a max weight of 45-55 lbs.

I should be able to post the results of the GPS log by the end of the day.
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Old Oct 06, 2012, 08:29 PM
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Ok so today I used the new rubber which was listed above.

I set the first few launches at 45 LBS and attained a somewhat lacking launch - then I took it another few paces past that stage - total paces ended up to 68 and at the end it felt like about 55- lbs - The launches were gaining altitude progressively each launch and ended up at 189 meters. The launch duration was a little slower as I predicted and wanted 3-4 seconds. There was enough time to anticipate the power or do a short "tow" if desired. However I was leaving a lot of stored energy in the system and I think longer line would invariably allow more alt without changing the launch scenario drastically.

There was almost no wind today and a couple times the wind thatt here was came in at 90 degrees/

I will put some more line on that bungee next test and see how the altitude measures out. I AM current using 75 paces of mono and will add another 25.

I have attached the GPS log to show the progress as I took the few extra steps and tension started to build
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Old Oct 07, 2012, 04:00 PM
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better results today -

The extra line was of bennefit - I felt like I was holding less tension and getting better launches - I have a total of 85 paces or maybe 191 feet of line - (1.25 mono) and I paced out to 85 paces of stretch.

The conditions were extremely flat and the last launch on the graph was actually at tad down wind as a themrmal was starting to form towards the end of the bungee -

For some reason the previous 8 launches did not show up on the gps logger ...im not sure why ill have to RTFM on that... I might have run it longer than it can handle the last flight was 20 minsutes and I did an hour of launches before that...

Regardless with even a 1-2 MPH headwind this launch system will deliver a decent launch of 200-250 meters without requiring a massive effort in terms of pull.
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Old Oct 08, 2012, 01:07 AM
kdt
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Mega bungee

My preference is still for a mega bungee...

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Originally Posted by webbsolution View Post
The extra line was of bennefit - I felt like I was holding less tension and getting better launches - I have a total of 85 paces or maybe 191 feet of line - (1.25 mono) and I paced out to 85 paces of stretch.

The conditions were extremely flat and the last launch on the graph was actually at tad down wind as a themrmal was starting to form towards the end of the bungee -

For some reason the previous 8 launches did not show up on the gps logger ...im not sure why ill have to RTFM on that... I might have run it longer than it can handle the last flight was 20 minsutes and I did an hour of launches before that...

Regardless with even a 1-2 MPH headwind this launch system will deliver a decent launch of 200-250 meters without requiring a massive effort in terms of pull.
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Old Oct 08, 2012, 03:10 AM
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My preference is still for a mega bungee...
My preference is for personal tow teams...thats not a sustainable solution - and I dont think a seriously high tension launch (70-90 lbs) is sustainable either. I dont think the average pilot is going to be able to use the mega bungee efectively and im not interested in catering to the super elite pilots at the expense of the complete future of the sport in our country. We need a middle ground that will allow us to build a critical mass and then we can amp up the launch scenarios.

DW
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