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RE: (Something Fast?) Delta Build Thread - 1/15/2008 3:38:44 PM   
Mike Connor



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From: Tulsa, OK, USA
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quote:

ORIGINAL: Speedy-Gonzales

Hey Mike!! Remember you sold me a second short kit? It's getting ready to go on the board with a fully cowled rear exhaust K/B 6.5cc Series II Quickee and mini pipe.

Is this going to be another work of art? There is always the option of a quick flat build and use it for a warm up plane. It will still be fast and it won't be as big a deal when the expiration date arrives. My flat fun fly Demon is quick and a blast to fly. I am sure it will be nice looking regardless of how you build it. We still have some time before much good flying weather arrives.

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RE: (Something Fast?) Delta Build Thread - 1/15/2008 9:35:45 PM   
Speedy-Gonzales


 

Posts: 275
Joined: 3/7/2004
From: Bryan, OH, USA
Status: offline 		Neither of these two planes are or will be meant to be a "work of art" but built to take advantage of their full capability. I don't believe in doing anything "Half Fast" ( that's a play on words ) I could never date an ugly woman. In retrospect I can not fly an ugly model. Oh yes... they must be clean too!!! This will be a much faster build since I have one build under my belt. Speedy

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RE: (Something Fast?) Delta Build Thread - 1/19/2008 1:59:58 AM   
Speedy-Gonzales


 

Posts: 275
Joined: 3/7/2004
From: Bryan, OH, USA
Status: offline 		I have also been giving some thought for a build with a K/B 3.5cc RE. I think with the 3.5cc it would still be quite quick and light. I would not fully sheet this model. I think a modest speed of 125 mph could be possible. I think the 125 mph mark would be the challenge with this setup. The O.S. .32 SX would be another possibility but I really want my next Demon to be rear exhaust. What do you think about the 125 mph goal with a K/B 3.5cc Mike?

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RE: (Something Fast?) Delta Build Thread - 1/19/2008 6:36:27 AM   
Mike Connor



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Joined: 1/10/2002
From: Tulsa, OK, USA
Status: offline
quote:

ORIGINAL: Speedy-Gonzales
What do you think about the 125 mph goal with a K/B 3.5cc Mike?

My experience is that breaking 16,000 rpm static with a 7 pitch will put you there. Doppler did show my winglet version breaking 130 mph in level filght with a 9 x 7 but I want to duplicate that before making any claims. I have not had an opportunity to test many props much under 9" diameter so I am not sure where a lack of thrust will be a problem with speed. So far my speed runs are in level flight and NOT out of a steep dive. I doubt there will be much further testing until the weather warms up some and I know your winters are colder then mine. I must be getting old because I like 60 degrees F or warmer to fly.

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RE: (Something Fast?) Delta Build Thread - 1/19/2008 3:05:45 PM   
Speedy-Gonzales


 

Posts: 275
Joined: 3/7/2004
From: Bryan, OH, USA
Status: offline 		My rules for claiming an achieved speed is in Straight Level Flight ( SLF ). You can dive before entering SLF but when in a verticle dive do you measure the speed before or after you make contact with terra firma!!!! There should be an approximate distance of 100 yards after returning to SLF, from a dive, before any timing or doppler measurement reading is taken.

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RE: (Something Fast?) Delta Build Thread - 1/19/2008 3:32:57 PM   
Mike Connor



Posts: 1384
Joined: 1/10/2002
From: Tulsa, OK, USA
Status: offline 		I believe the rules used at the German speed cut allowed a steep dive plus the altitude variation allowed through the traps could be used for a slow decent.

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RE: (Something Fast?) Delta Build Thread - 1/19/2008 10:19:05 PM   
gooseF22


 

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From: Fort Wayne, IN, USA
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quote:

ORIGINAL: Mike Connor

These A123's sound interesting. I guess the downside is weight?


The downsides are voltage, size, and weight. This is offset by the positives of C rating and safety and charging. The size on them are about like a long C cell. They are very robust and safe, they can withstand severe heat, and charge at 4C...usually at max amps of any charger. THe other part is that being 3.3 volts nominal it takes one or two additional batteries to equal lipo voltage.

for instance on my bobcat, I ran a 3000 MAH 4S and it achieved pretty good results with the 2500 kv and 6x4 prop. It did about 67 amps in that setup.

Without changing anything, I switched to a 6S A123 battery pack with heavy wiring, 2300 Mah, and the voltage under load was close. 13.9 volts and over 70 amps, and the overall weight was a wash because the lipo pack was heavy kokam. I didn't mind weight for the speed...helps actually. In most apps, it adds about 25% weight if using for main power. But using a UBEC works great because you cannot kill them. I get about 2.3-2.5 volts per cell under 60+ amp load with them.

The cells weigh 2.75 oz per cell. so they are lighter than a 5pack of nickles, but heavier than Lion and lipos

I also use them in a 2S config for Receiver batteries unregulated. they come in 2300 versions (dewalt packs) and 1100 mah (VPX packs) but require a max of 7.5 volt cutoff instead of an 8.4 volt CC/CV charge. I charge them at 6 amps often. Over 1000 cycles.

People are making packs now, and several chargers have LiFe programming now. I do believe its the future in modeling. They hold their voltage great...very flat, but require different checking.

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Team Fromeco

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RE: (Something Fast?) Delta Build Thread - 1/19/2008 10:40:58 PM   
Mike Connor



Posts: 1384
Joined: 1/10/2002
From: Tulsa, OK, USA
Status: offline 		Thanks, it sounds like you know your electric stuff pretty good. Please post pics of your setup when you get to it so I can ponder my plunge into electrics.

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RE: (Something Fast?) Delta Build Thread - 1/20/2008 1:58:01 AM   
freakingfast


 

Posts: 807
Joined: 1/3/2005
From: mather, CA, USA
Status: offline 		I dear say, that the future of RC and speed will be electric. The over reactive environmentalists will soon see that our little two stroke RC engines are the major cause of global warming and ban our nitro fuel, LOL. The first clue that something is up when OS released a "green" 55AX-BE (Bio Ethanol). Here in California our gas powered little weed whackers, chain saws and leaf blowers now have catalytic converters, and run like c**p. I’m not kidding!

I like it when I see guys working out the details on electric speed deltas so that those of us that have nitro in our veins can convert to electrons and not create a total dog of a plane. I'll sit on the sidelines a bit longer to see how the prop, motor and battery combinations pan out.

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pieces fit easier in the bag! Revver Bro #201

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RE: (Something Fast?) Delta Build Thread - 1/20/2008 3:28:35 PM   
Mike Connor



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From: Tulsa, OK, USA
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quote:

ORIGINAL: freakingfast

Here in California our gas powered little weed whackers, chain saws and leaf blowers now have catalytic converters, and run like c**p. I’m not kidding!

I like it when I see guys working out the details on electric speed deltas so that those of us that have nitro in our veins can convert to electrons and not create a total dog of a plane. I'll sit on the sidelines a bit longer to see how the prop, motor and battery combinations pan out.

Catalytic converters on chain saws may be a sign there are too many people on this planet. Some day it will make its way to Oklahoma.

I am also watching the electrics making progress. I will probably end up using Li-Po batteries since I am such a weight freak. Seeing an electric delta at 150 + mph with a 5.5" prop will probably push me over the edge. I think it will happen by Spring.

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RE: (Something Fast?) Delta Build Thread - 1/22/2008 3:01:59 AM   
gooseF22


 

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Status: offline 		Mike
I posted pics of the little bobcat awhile back, its the identical power plant. Will post the build pics sometime soon I hope, been on the road alot lately.

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RE: (Something Fast?) Delta Build Thread - 1/22/2008 11:41:49 PM   
Speedy-Gonzales


 

Posts: 275
Joined: 3/7/2004
From: Bryan, OH, USA
Status: offline 		Do you guys believe the doppler method of calculating actual speed of a model aircraft is accurate? Has anyone ever challenged this notion. I am sceptical but will accept doppler readings if anyone can actually prove they are accurate. Do you have any factual references showing accuracy compared to radar or photo triggered measured timed distances. I am curious if anyone has actually proven the accuracy of the doppler software for giving such readings.

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RE: (Something Fast?) Delta Build Thread - 1/23/2008 12:30:01 AM   
gooseF22


 

Posts: 662
Joined: 8/12/2006
From: Fort Wayne, IN, USA
Status: offline 		I think mike has hit it pretty close.

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RE: (Something Fast?) Delta Build Thread - 1/23/2008 12:58:28 AM   
Mike Connor



Posts: 1384
Joined: 1/10/2002
From: Tulsa, OK, USA
Status: offline 		I-Love-Jets from Germany in the NC speed thread recently claimed extensive comparing of photo triggered timed distances and radar. He claimed the radar was often up to 10% fast.
http://www.rcuniverse.com/forum/m_6897619/mpage_2/tm.htm
It sounded fairly convincing and may be true but HighPlains came in right behind him and put doubt in my mind.
We usually do not have photo triggered times so we use other methods. The writers of the Doppler program show a 1%-5% margin of error and I feel that is close because of my comparisons.
In the Speedboy video, Doppler and radar were very close.
In the SlipStream video, Doppler and radar were vary close again.
A check against Bob27's Q40 was again very close.... and the list goes on.
My thoughts are that if more then one method of checking speeds are close to each other it will give you a pretty good idea of how fast you are going.

< Message edited by Mike Connor -- 1/23/2008 12:59:32 AM >

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RE: (Something Fast?) Delta Build Thread - 1/23/2008 1:18:46 AM   
iron eagel