Mustang Fever

My Feedback: (2)

I dunno, Roundy. When I bought them in early 2006, I remember looking at both websites and it seemed to me they were identical. I checked the Spring Airs last night, and they look totally different from what I remember. As far as the Robart spring downs (521RS at Tower), the retract mechanisms themselves were fine, aside from a lot of slop in them that everyone else but was complaining about, but the valve was unreliable. It kept sticking, and it had so much restriction on the vent (extend) port that it caused problems with gear deployment. I made at least three gear up landings with them before I hit on the solution of using a Robart #174 Gear Door Valve to control them. I could use a micro servo with it, and merely adjusted the travel so the valve was stroked fully on gear up, and fully extended on gear down. It was not only 100% reliable, but it didn't have the restriction of the standard valve, and the gear worked much better. I was able to put a restrictor orifice in the pressure line to slow the retract cycle down a little, but left the extend vent alone, and it all worked very nicely. I liked it so much that I also used one for air brake application, as I could T it into the elevator servo circuit, and get braking upon full down elevator.

Oh, I also agree with you on sticking with Robart (mostly, anyway). The stuff is high quality and readily obtainable, and that counts for a lot. I've kind of come down against spring down systems in general, though, as they eliminate two of the big advantages of retracts: less space required to store and transport the airplanes, and less chance of damaging them by hooking the exposed gear on things when loading, unloading, etc. I've got a P-51 with a pair of the 531RS units, and love em.

theo63

HEY JIM IF IT HELPS AT ALL my motor will not be here untill at least 3 weeks,guess ill just have to get done what i can and move on to the wings i can get them done by then they look pretty simple,my retracts took about 2 weeks i hope they come thru for ya might be the holidays i think they are a pretty small outfit but i really dont know steve

jaaron01

Like I said last night, they finally responded to me, and told me they mailed them yesterday. So I would expect to see them sometime in the next week. I went flying today in about 11 degrees, with a 5 mph wind. After about 2 hours I was frozen, but at least I got a flight in the month of December.........time to warm up and get back to work on the Su-27.

Jim

jaaron01

Started work on one rudder, and finished the sheeting on one side. Also started re-enforcing my retracts area, as I fly mainly from a grass field, and everyone seems to have ripped out one retract side or the other. I think the added hard wood will give more bit on the retract mount plate, and allow a little more abuse.

Jim

jaaron01

Just when I thought I couldn't go any further without the retracts, guess what showed up!!!! The retracts have arrived, however the was no pump[&o]. So I rigged up and old bicycle tube valve, and a piece of leftover air line , so that I could charge the system with my shop compressor. Spring Air did include a check for the pump, so hopefully I can go to the local hobby store and get a pump.

jaaron01

Is anyone planning on putting in the Air Brake feature thats on the Su-27. Anyone have any ideas on accomplishing this, and keeping it simple?

Jim

Sparhawk

Jim,
See pic. I would add some vertical sheeting (light ply) in the red area because the retract area gets kinda thin there due to the cut out for the wire.
If you add some strength here, like shear webbing does, it will not crack here due to a hard landing. So support it in this area.

Trust me, it works to stiffen this area before you sheet in the engine intakes.

Dan

jaaron01

Sounds like a plan. I was actually thinking about adding something there to keep dirt/wind from getting up in there. If you look at the picture you'll see I only have the outside bolts in the retract. I ran out of blind nuts, so I just put the two outward screws in, as I can reach the inner ones. I've got one side epoxied into place and drying, so in the morning I'll add the light ply to the side.

I've been looking at photos that show the air brake. I'm thinking of keeping it simple with just a long servo arm, with an extention and a robart control horn epoxied in the center of the hatch. Check out the photo below. Any thoughts?

Jim

jaaron01

Well good news and bad news. I charged the retract system early last night, and this morning the gear is still in the up position, so no serious leaks that I know of. Of course I don't have a gauge to check the pressure, but I could still cycle the gear about 5 times.

Bad news, is first thing this morning I drilled a hole in my retract plate for the wing screw, and drilled it wrong. So now I've got to fill these with epoxy, let them dry and redrill tommorow. I hope this isn't a sign of things to come for today.

jim

Mustang Fever

My Feedback: (2)

Jim:

Do you have any milled fiberglass to mix with the epoxy? Plain epoxy will eventually crack, as it has no inherent mechanical strength. I'd send you some through the mail, but they'd probably think I was some kind of terrorist, as it looks like a white powder.

http://www3.towerhobbies.com/cgi-bin...?&I=LXK312&P=7

jaaron01

As for mechanical strength, no is needed. Just need to fill up the hole, so I can redrill and not have the wing holddown bolt, moving around. Once it's been redrilled, the rest can fall out if it wants. The wind bolt goes through and screws into a block on the back side under the skin of the wing.

I just went to the hobby store and found some 2 3/4 diamond lite wheels from dubro for 8.06 a pair, can't beat that price.......maybe my luck for today is changing.

Jim

jaaron01

After I put the 3/16 wire struts, and placed the wheels on, I soon realized that this wasn't a pretty picture. Nothing was lining up as was supposed to. I've adjusted the wheel cut outs, had to adjust the wheel mount itself so that it would freely operate with the strut. Now for the next issue, the wheel hub itself is rubbing on the outer side of the engine cover. (see attached)

I've adjusted everything else as much as possible, so it looks like I'll have to add a 1/2 piece of balsa behind the engine side for thickness. Then make recess in the shape of the pencil markings so that the hubs won't rub, and allow plently of clearance. Anyone else have issues installing there retracts?

Jim

jaaron01

So here's the damage has been done, and here's what I came up with. It'll be fun covering around this, but at least the gear functions perfectly, and nothing rubs. One more side to do, then on to the front. I spent most of the day today working on this one side and getting everything to function.

Jim

jaaron01

Here's the photo's.....they didn't load the first time....

Mustang Fever

My Feedback: (2)

Jim:

If there's a landing gear setup for a kit or a plan set that works without cutting and pasting, I haven't found it. You're doing good. You wouldn't believe what it took to get a nice set of retracts into a 1/7 scale TopFlite P-51.

jaaron01

Mustang Fever: Your obviously right. I've never dealt with retracts before, but I figured there would be some adjustments that needed to be made. My biggest fear is my club airfield. We've got about a 200 ft blacktop runway with grass at either end, and this plane is sure to over run that and be in the grass. The grass at the end of the strip is mowed, but not smooth by any means.

I'm still thinking about the air brake. I was wondering if a body hooked up flaperons on a three position switch if they'd work. My idea was set the switch to Up = normal ailerons , middle = flaperons about 8-10 degrees??, and down = full up air brake & a little more flapersons/flaps. Obviously you wouldn't active the full down switch until the mains were on the ground / used only to keep from overshooting the black top. Any thoughts???? Think it would work / I'm sure it would depend on the size of the airbrake and it's effectivnes.

Jim

Steelie

My Feedback: (18)

What about trying this method for slowing it down? http://www.skymasterjet.com/image5/1692.jpg

Mustang Fever

My Feedback: (2)

Jim:

I had a prop in the nose F-4 Phantom that I only flew on paved runways. I put compressed air operated wheel brakes on it, Bob Violett brand. I had a small micro servo that operated a Robart gear door valve. The servo was t'd into the elevator channel, so that full down elevator would apply the brakes. I used the same air tank that the retracts operated off of. Worked great. Made the airplane very controllable on the ground.

After having been intimately involved with two premature parachute deployments, I was understandably a bit nervous about going that route.

jaaron01

Mustang Fever: Yeah, I'm not going to go the paracute route. I'm beefing up the retract plates, to take the abuse. I'm also going to work on the air brake. Hopefully today i'll get her up on all three.......

Jim

Steelie

My Feedback: (18)

Ok....Bob and Jim,....what about this method? http://lh6.ggpht.com/_ckk9XZCU7o0/Rc...-5345W-242.jpg

Come on guys, work with me. I'm running out of ideas. Landing this way simply would require sooo muuuch practice. That's all...

Mustang Fever

My Feedback: (2)

Steelie:

The link didn't work, but I'll bet it has to be a Pogo Stick or something like that.

jaaron01

So this morning I've at least got her up on two legs, gotta wait for the third until the hobby shop gets my other adjustable axels in. I had to buy the 5/32 axels by Dubro, then drill them out to 3/16. Hopefully by thursday the other set will be in, and I can get the front put together, however there's still plenty to do. I seen right off the bat, the front ply cover for the nose gear, is going to need some serious trimming like the rears.

I did find a solution to control horns for my 1/8 wire that I bent for the elevator / rudders. They are made by dubro as well, and of course they had to be drilled out a little, but they are just what the doctor ordered, adjustable up and down as well.

Starting to get ready for the wings, so I assembled the W-1 lite-ply and balsa, and also added a 3/16 wooden dowel for extra aligment. I worried about the rear being align by the wing tube, and the bolt plate, but the front just hanging there. Probably wasn't necessary but can't hurt anything.

Jim

theo63

jim,sisnce i seen your post i decided to check mine out and i do not seem to have the problems you had with clearance check mine out in the picture i have to do some sanding to get a good fit but not like yours i wonder why
i have been working on mine but progress seeems slow im getting things done but just seems to drag on at this point,i too think ill move on with the wings for now as i am waiting on parts and my motor will not be here for some time steve

DaCrew

I noticed that the images in post 1187 show the spiral for the landing geat spring going towards the fuselage.

In post 1198, the spiral on the spring goes outward. This would provided extra clearance over the first installation by 2 x the diameter of the wire?

Cheers.

DaCrew

jaaron01

Your correct on the spring facing different directions. I tried both ways, and maybe it's due to the type axials I'm using as they are a little more beefy than what theo63 is using. Turning the spring one way cause the axial to dig into the side of the engine nacelle, turning it the other way caused the tire not to clear the inner edge of the wing plate. Choices had to be made, and I decided it was more important to have plenty of clearance, instead of having things within 1/16 - 1/32 of each other, as things will get bent.

My kit also could be cut different that others, as I posted when i first got the kit, the servo bays didn't align with each other, along with a couple other minor things I've noticed and had to compensate for. Not a big deal, I'm still a happy camper.

Jim