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Old Feb 01, 2003, 06:51 PM
Tear down the WALL!
ralf dvorak's Avatar
southern Germany
Joined Oct 1998
1,396 Posts
wheels

Quote:
Originally posted by uncljoe
Gregg
FWIW .. I would use the Sullivan Skylite wheels they are the lights/ hardest wheels out there .. I use them on all my larger planes,they work.will hold up
the plane will need it 6 pounds ...
Semper Fi
Joe
gregg will have some custom made wheels posted on monday flying GAF to the US.
cheers, RD
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Old Feb 01, 2003, 07:15 PM
Purple power
gregg f's Avatar
shadow hills,ca
Joined Apr 2000
6,594 Posts
Re: wheels

Quote:
Originally posted by ralf dvorak
gregg will have some custom made wheels posted on monday flying GAF to the US.
cheers, RD
excellent
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Old Feb 02, 2003, 09:57 AM
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Joined Aug 2000
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Ralf

I noticed the noseleg down-assist spring on the photo posted by Gregg, and wondered if that means you had hang-up problems with the 602 noseleg.

I certainly did with my MiG 15, and on a couple of occasions, the noseleg came down for landing, but didn't lock (no green lights on my Tx so I couldn't tell ) so that on touchdown, the noseleg folded back and dropped the nose onto the tarmac. Fortunately the dummy cannon fairing took the full wear and tear of the incident, so the inlet was undamaged.

After the first occasion I assumed that the sliding bar and pivot block were interfering, producing excessive friction and preventing the springs from forcing the leg fully down. So I dismantled the nose retract fully, and polished all sliding surfaces and lubricated them. I noted at the time that the noseleg down spring has 2 concentric springs, compared with just one spring in the mains. The extra spring is presumably to help overcome air resistance when the noseleg is lowered. I also carefully rounded and polished all the edges of the steering arm so the cables couldn't snag in a burr. The cable outlets were/are in the best position for eliminating hang-ups, BTW.

The darned noseleg still failed to lock down on a subsequent flight, dropping the nose onto the tarmac again. I decided then that the steering cables had somehow caused the hang-up, so before the next flight, I did some serious bench testing, and found that indeed, the cables were party to the hangup ......

...... but the fault didn't lay with the cables. The problem was with the air valve supplied with the 602s, which had a different way of working than the air valves on the first Springairs I ever bought many years ago.

The basic problem was that the new air valve which came with my 602s has a restriction built into on the dump side of the valve, so although they banged up with enough force to cause a wheel to crack the top wing skin above a mainwheel well during the first bench retractions I tried, they only came down slowly. During the slow process of lowering the noseleg, one or other of the steering cables was able to twist in such a fashion that it could snag on the steering arm, and stop the leg from locking down fully.

The solution was to replace the supplied air valve with one of the old type, which has no restriction on the dump side, and lets the legs bang down (as well as up) with gusto, preventing any chance of a steering cable hang-up.

At the same time I introduced restrictors into the main gear air lines, so that the mains didn't operate so forcefully and keep bustin' the wing skin.

Since changing the valve, I have had no problems with the noseleg failing to lock.

Of course, perhaps your extra spring is merely to help the noseleg overcome the air resistance of the nose door.

However, for those who are interested, and have suffered the same problem (or are about to ) the old type valve, code no SMTV-3, is still made by Clippard Pneumatics, and a Google search on that name will turn up their suppliers in your country. The valves are not cheap - mine cost nearly £45 for two, and I bought them from a UK supplier. But they were the difference between a serviceable set of retracts, and an untrustworthy one.

The photo below shows the SMTV-3 on the left, and the cruddy replacement, which has a black plastic lever, on the right. Note that in use, one has to bore a hole in the end of the SMTV-3 lever for the servo pushrod.

If anyone has any better/cheaper ideas not involving extra springs, I'm not averse to any suggestions!

Sorry about the length of this post, and hope it helps.

Gordon
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Old Feb 02, 2003, 11:22 AM
Flying Welder Pilot
Plane Crazy's Avatar
Reno, Nevada
Joined Jan 2001
1,137 Posts
Badges? We don't have NO badges!

A little Frito Bandito action EH!

EEEEEEEEEHAAAAAAHHHH...

Check out those bionic knees

Gordon
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Old Feb 02, 2003, 11:36 AM
Purple power
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shadow hills,ca
Joined Apr 2000
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rofl
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Old Feb 02, 2003, 02:39 PM
Acme Powered!
Joe Elston's Avatar
Orange,CA
Joined Jul 2000
4,040 Posts
Mini Spring Air Valves

Gordon, I bought the adjustable Robart retract valve for both sets of my Mini 602 Spring airs. And its adjustable for up and down speeds for the Spring Airs so I am hoping that this will keep the problem happening at all. I like the Robart valve because as I said I can control speed in both retract and deployment phases I will just make sure that I dont slow down the nosegear too much so as it wont come down. And yes the cables for steering can really be a tricky set up. I use 25 pound fishing line for my steering cables it works and is readily available.
Joe
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Old Feb 02, 2003, 03:12 PM
Col.Hooligan Air Force
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Phoenix,Arizona
Joined Jul 2001
1,205 Posts
JJ
Spring Air require no air for the deploy Down as a spring does the work. Fishing line will work but why not use the correct wire(hardware) fo the job. Du-bro has a PULL-PULL system for about 6 bucks with 15 ft of cable enough for many- many models JMO
Semper Fi
Joe
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Old Feb 02, 2003, 03:42 PM
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Orange,CA
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Spring Airs

UJ, while you are correct that the spring is what deploys the landing gear on the Mini Spring airs and other Spring Airs as well. They are held up in the retracted mode by air. Air holds them up and the release of air is what allows the Spring Airs to deploy. Hence when or if you lose air pressure in the system they automatically are deployed by the springs. However since the retracts a held retracted in the up mode, you can control the flow of air in the deployment with the adjustable Robart valve so that it will allow the Spring airs to deploy at a much slower speed than just slamming down. Check it out with Spring Air they will tell you the same thing as they stock the Robart valves and where the people that brought this to my attention

As for the fishing line I just got used to using it for my other retractable gear models and its cheap and light and works well. I am sure there is stronger and better solutions but that was my MHO.
Thanks Joe
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Old Feb 02, 2003, 03:54 PM
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This photo shows the original problem, which I've set up specially. It never happens now during undercarriage extension.

As you can see, one of the steering cable loops has fouled the smoothed-off steering arm. What you can't tell, but which has happened here, is that the leg hasn't locked down, due to the cable in the right-hand side of the picture now being effectively 1/4in shorter because it's hung up, and holding the leg slighly aft of where it should be. This can happen, and in fact almost always does as the leg comes down. Restricting the airflow out of the nose unit to make the leg come down slowly allows the loop to hang up as shown, and the leg will not lock.

If you let the leg bang down, the loop is forcibly slid round the steering arm into the same position as the loop on the left of the picture, and the leg locks down fine.

So my experience and advice for 602 users is that although it's ok to slow the mains up or down, and to slow the noseleg going up, it's not ok to slow the noseleg via restrictors in the down direction.

Gordon
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Last edited by Gordon; Feb 02, 2003 at 04:03 PM.
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Old Feb 02, 2003, 04:04 PM
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Joe Elston's Avatar
Orange,CA
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Nose wheel

Gordon, there has got to be a way to allow the nose gear to come down slower than stock and not have it held back by the steering cables. It would seem to me that there must be a solution but I understand what you are trying to tell us. I will look at mine and see if I can figure out something. If I come up with something that works so that I can slow the nose wheel down I will share it with the board in this thread.
Thanks Much Gordon for the heads up.
Joe
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Old Feb 02, 2003, 05:34 PM
Tear down the WALL!
ralf dvorak's Avatar
southern Germany
Joined Oct 1998
1,396 Posts
Quote:
Originally posted by Gordon
Ralf

I noticed the noseleg down-assist spring on the photo posted by Gregg, and wondered if that means you had hang-up problems with the 602 noseleg.

Of course, perhaps your extra spring is merely to help the noseleg overcome the air resistance of the nose door.

Gordon
Gordon, I had the same problems on the first flights, true, and I traced it to the front nose door. Since the additional lockdown spring installed there were no hangups anymore.

The steering wires (plastic coated brass wire with fitting squeezing rings) are supplied in the RG kit.

Cheers, RD

*really gone skiing now, worked on the kits until just now*

@gregg: he's getting a set of wheels, the english RG instructions and the new vacuformed wing humps leaving here tomorrow.

@all other orderers: this will all be included in your kits (wheels if ordered)
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Old Feb 02, 2003, 07:23 PM
EDF Jet Jam 2015, May 28-31st
Robert Belluomini's Avatar
United States, KY, Crestview Hills
Joined Dec 2000
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Quote:
Originally posted by Gordon
Ralf


The solution was to replace the supplied air valve with one of the old type, which has no restriction on the dump side, and lets the legs bang down (as well as up) with gusto, preventing any chance of a steering cable hang-up.



However, for those who are interested, and have suffered the same problem (or are about to ) the old type valve, code no SMTV-3, is still made by Clippard Pneumatics, and a Google search on that name will turn up their suppliers in your country. The valves are not cheap - mine cost nearly £45 for two, and I bought them from a UK supplier. But they were the difference between a serviceable set of retracts, and an untrustworthy one.



Gordon
Gordon,
Clippard is a customer of mine and is just a mile down the street. I work with the marketing guys. If you or anybody else ever needs one of these values let me know and I'll be happy to get you one.
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Old Feb 02, 2003, 08:24 PM
Col.Hooligan Air Force
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Phoenix,Arizona
Joined Jul 2001
1,205 Posts
FWIW..I've never had a problem with the gear "Slaming down"with that method ,I know I, have a gear down and locked .....Why would you want to slow the gear coming down? I have had used Spring air & robart systems Just My real world experiences
Semper Fi
Joe
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Old Feb 02, 2003, 08:42 PM
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Orange,CA
Joined Jul 2000
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Slowing gear

UJ, I too have used all types of retracts and I was just thinking of slowing the gear down so the deploy and retract at a more scale speed. You will see at scale contests that if your gear retracts or deploys too fast you can lose points on you static and flight scores. I guess it was a question aimed more at super scale models and I really dont need to worry about them much as I doubt I will be competing at the Scale Masters anytime soon
Joe
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Old Feb 02, 2003, 08:58 PM
Col.Hooligan Air Force
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Phoenix,Arizona
Joined Jul 2001
1,205 Posts
JJ
You'll have to tell me what scale event you would enter a El Bandito in. I fly scale both electric & turbine & I have yet to have any points deducted because of too fast or too slow retracts, at least in the past 3 years.AMA & 1/8 airforce events
Semper FI
JOE
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