Author Topic: retracks for stunt (Read 4428 times)

Randy Snow · « **on:** April 09, 2012, 09:37:42 AM »

While at the Tucson VSC I learned of retracks being used in stunt -- their set to retrack after airborne and then extend after the engine shuts down - audio activated - can anyone give me the info on these? who makes them & where can I get them?

Tim Wescott · « **Reply #1 on:** April 09, 2012, 09:55:59 AM »

If you fly electric, some of Will Hubin's timers feature a retract channel.

peabody · « **Reply #2 on:** April 09, 2012, 10:29:54 AM »

Some fairly serious and pretty good fliers have built planes with retracts....... I believe that the consensus is that those reliable enough are simply too heavy....
Have fun!

dennis lipsett · « **Reply #3 on:** April 09, 2012, 10:34:15 AM »

I saw a young man fly an electric at the KOI with retracts and he did a great job of flying and the retracts worked perfectly. Altogether it was the best electric model and flight that i have seen to date. If they are'too heavy' it surely was not apparent in the performance of that model. E flite makes some truly great electirc retracts that would /are perfect for our purposes.

Dennis

dankar · « **Reply #4 on:** April 09, 2012, 11:00:21 AM »

I have seen that airplane at VSC, but not in flight. Bob Whitley had a Mustang that had them years ago. Looked great in flight. Problem is extra work and when they fail, bad news. The new elecrtic stuff works pretty good and lite.
Dan

PerttiMe · « **Reply #5 on:** April 09, 2012, 11:11:55 AM »

I suspect the main benefit of retracts would be the coolness factor.

FLOYD CARTER · « **Reply #6 on:** April 09, 2012, 12:37:31 PM »

I now have three stunters with retract landing gear. Our friends in Hong Kong have some nice self-contained electric retract units (no R/C servos or those pesky linkages that bind or bend). The electronics unit I build myself.
Rather than take up space here, if you need more information, please contact my e-mail. Let me know the size/weight of your plane.

Floyd

floydecarter at gmail dot com

peabody · « **Reply #7 on:** April 09, 2012, 01:42:13 PM »

I had a conversation with Bob Hunt about retracts once....he was/is a true proponent.
The Mustang that he designed (flown by Danny Banjock and Mike Palko) was designed for them.
Bob explained that the drag reduction was greater than the weight sacrifice...then came some significant failures.....just saying

Had greeted rather than greater....oh well

dave siegler · « **Reply #8 on:** April 09, 2012, 02:14:29 PM »

electronics are off the shelf stuff

http://www.emsjomar.com/SearchResult.aspx?KeyWords=control%20line

Douglas Ames · « **Reply #9 on:** April 09, 2012, 03:25:12 PM »

Quote from: FLOYD CARTER on April 09, 2012, 12:37:31 PM

I now have three stunters with retract landing gear. Our friends in Hong Kong have some nice self-contained electric retract units (no R/C servos or those pesky linkages that bind or bend). The electronics unit I build myself.
Rather than take up space here, if you need more information, please contact my e-mail. Let me know the size/weight of your plane.

Floyd

floydecarter@gmail.com

Howabout a separate thread on your systems? What's your source in Hong Kong?

Howard Rush · « **Reply #10 on:** April 09, 2012, 04:00:21 PM »

I suspect that drag of retracts is less than that of fixed gear. I figure draggy gear (assumptions available by email upon request) uses 85 mA-hr. of a 5-cell battery for a stunt flight. It would be hard to put holes in the wing for less drag. For an IC engine, drag is not a consideration.

Oops. I just noticed the above on 4/11. I meant to say that the drag of retracts is greater than that of fixed gear.

SteveMoon · « **Reply #11 on:** April 09, 2012, 04:05:17 PM »

The new (or rather somewhat newish) electric retract units from E-flite
are much simpler to operate. And are readily available, come in several
sizes, and are lightweight.

Later, Steve

Robertc · « **Reply #12 on:** April 09, 2012, 04:11:00 PM »

I built three planes using the Jomar retract controller. This is the sound activated one asked about. Never had a problem with them. It is more work.
To me the biggest advantage was the wow factor. It did make the insides and outsides pretty much the same as far as handle input, but if you
fly a plane enough, you adapt quickly to input anyway. May do another one, but not on the drawing board right now.

Mike Keville · « **Reply #13 on:** April 09, 2012, 04:52:48 PM »

While I don't know which system he used, Bart Klapinski's twin-engined "Two Much" had retracts. They worked flawlessly. Unfortunately the model crashed last year, and is now in the process of being repaired.

Randy Snow · « **Reply #14 on:** April 09, 2012, 06:01:55 PM »

Robert does the Jomar system need an E-flite system in order to operate or is the Jomar a complete system - I am so new to this stuff -- that ripvanwinkle thing -LOL- someone at VSC said that there was a system to operate that Mustang inner door trip -- when the Mustant sat the hydraulics leaked pressure and the inner doors would drop open - as soon as pressure built up after engine start up the inner doors would pull closed - then after airborne when the retrack toggle was thrown the inner doors would open - gear retrack then inner doors would close again -- toggle thrown for gear tobe lowered the inner doors would open down comes the gear and then inner doors would pull back into their closed position -- till the hydraulics would loose their pressure after engine shut down -- was told the model system had inner doors closed to start with - then open - up gear - close - open - down gear - then close again -- -- seriously North American and their Mustang -- I read that this system for their Mustang gear was only for the "look" as the ship sat on the flight line and nothing more -- just because the ship looked "so cooool" as it sat there -- like a race horse showing off . More real Mustangs are flying than all other WW2 fighters combined.

Robertc · « **Reply #15 on:** April 09, 2012, 06:12:03 PM »

The Jomar unit is the controller. You need the retracts and a retract servo. I was using the Robart 600's. In addition, you need a battery (4.8v) around 100 - 150 mah.

Avaiojet · « **Reply #16 on:** April 10, 2012, 10:46:38 AM »

We used retracts for years in R/C Pattern. PITA.

I don't remember who, but someone came along and started winning Pattern contests with a fixed gear model.

Didn't take long for the wave to travel through the Pattern comunity. Decided they weren't necessary?

Retracts are hardly now, well, unless you fly Classic Pattern.

Charles

Mark Scarborough · « **Reply #17 on:** April 10, 2012, 12:15:49 PM »

From my studies about pattern ( RC version)
retracts went away when the older style ballistic pattern ( flown at 120 mph with HUGE towering manuevers, piped .60s ) went away. Sound restrictions came first with the high rpm motors going away and torque systems came into play. then the actual sequence changed making the ballistic fast planes no longer suitable. When RC pattern started to value more compact schedules, the speed came way down, and now reliability is paramount to speed. Retracts have no gain in todays pattern since the speeds are so slow relativly. Watching current pilots fly pattern is more like what we do in CL aerobatics than it is old school pattern ...

Trostle · « **Reply #18 on:** April 10, 2012, 12:52:07 PM »

Quote from: Avaiojet on April 10, 2012, 10:46:38 AM

We used retracts for years in R/C Pattern. PITA.

((Clip)

Retracts are hardly n[e]w, well, unless you fly Classic Pattern.

Charles

Well, duh

Avaiojet · « **Reply #19 on:** April 10, 2012, 03:30:20 PM »

I left out the word "used."

Should have read, "Retracts are hardly used now, well, unless you fly Classic Pattern."

Didn't even get it right.

Charles

David M Johnson · « **Reply #20 on:** April 11, 2012, 05:22:59 AM »

A few years ago I picked up a pair of retract systems that used the centerfugal weight of the plane to retract the wheels. Any one ever use those ?
David Johnson

PJ Rowland · « **Reply #21 on:** April 11, 2012, 05:32:45 AM »

Howard : For an IC engine, drag is not a consideration.

yet one more reason to stay with the IC Revolution....

Paul Smith · « **Reply #22 on:** April 11, 2012, 06:28:35 AM »

In stunt drag is good.

It lets you keep the horsepower up and the airspeed low. This is the reason the Al Rabe school of design beat the streamlined jet look.

I agree, retracts would look cool. The old retract gear Crusader used an air pump connected to the engine working a cylinder against an extension spring. When the engine quits the pressure drops and the spring lowers the gear. This solved the problem of lowering the gear if the engine quits early. It always seemed sort of power-robbing to me, especially on a Fox 35 Stunt.

Tom Niebuhr · « **Reply #23 on:** April 11, 2012, 11:22:55 AM »

"Retracts are hardly used now, well, unless you fly Classic Pattern."

That is absolutely not true. While Harold Price had retracts on his Crusader, you will be very hard pressed to find many more.

Most retract systems are more recent, with the system used by Bob Whitely, Robert Compton and a few others being the most prevalent until now. Today many are starting to use electric retracts which are more easily programmed with the electric setups.

Howard Rush · « **Reply #24 on:** April 11, 2012, 04:17:08 PM »

Quote from: Paul Smith on April 11, 2012, 06:28:35 AM

In stunt drag is good.

Except for electrics, where it uses more electricity. Retracts are easy to do for an electric airplane, but I think the coolness would be somewhat overpowered by the weight and drag increase and the consequences of gear-up landings.

uwe kehnen · « **Reply #25 on:** April 11, 2012, 04:22:35 PM »

Hi Randy
I wrote a few years ago an article about my retracts for stuntnews.
You can read it on my wife's homepage.
http://www.fesselflug.eu/html/stuntmodel_with_retracts.html
I think it is more or less valid.
The only change I would do is to use the E-Flite gear.
They have meanwhile a set with 1/8 wire instead the 3mm wire at the beginning.
I would use the little heavier version to make the system more reliable.
The reason to go to an electric gear is to make it simpler.
(no complicated linkage, no heavy servo)
Hope this helps you
Kind Regards
Uwe