vol4ever

Bought this kit in late 2007, and then found out we had been selected as an adoptive family for a little girl due to be born in March 2008. Then found out in Jan 2008 that my wife was PREGNANT. So we had a daughter born in March, and then back in the hospital for a son in September. Not hard to imagine that RC took a back seat for a few years. This past weekend, I rearranged my workshop (while tripping over big wheels, tricycles, sandboxes, etc!) and set the bldg table back up. I don't get to spend hours at a time, but I have officially re-entered piddle mode.

Planning for this plane to be my first with mech retracts. I remember reading somewhere that folks recommended moving the landing gear out one bay from what is shown on the plans to allow for slightly taller gear / more ground clearance. However, the only threads I can find in my archive are specifically talking about the US 60. Does the same recommendation hold true for the US 40+?

Looking forward to getting back into this, and looking more forward to the day when my son will be old enough to enjoy "hobby time" with Dad.

~Vol

MinnFlyer

My Feedback: (4)

Good for you on all accounts! And yes, moving the retracts out is a good idea on ALL Ultra Sports.

foodstick

It is amazing how many times you hear of a homegrown showing up with an adoption ! maybe the knowing you will be a parent soon triggers something internal...

Great to hear you are back to work on your kit..going to have students at home to teach soon...

Did you adopt an arf before starting the kit again?

HFrank

Good luck with your US Plus, it is my all time favorite sport plane, very capable yet very forgiving. [8D]

vol4ever

Did you do the gear relocation like everyone else is recommending?

HFrank

Nope, I built it tail dragger with fixed gear, stock location, (I like the K.I.S.S. philosophy) ground handling is easy. Prop is APC 12.25 x 3.75, engine is a Magnum .52 XLS. This combo is a BLAST, very fast and endless verticals, I have to cut the power when the plane is just a tiny dot in the sky.

vol4ever

I've never done retracts before. I was doing them on this one for that reason really more than anything else. Just wanted to see how it handles, and it should be cool watching the gear open & close.

Wonder if I'm just asking for trouble, though? I'm an intermediate builder with only a couple of kits under my belt back before kids. Last one I built was a Midwest Super Hots 60 taildragger that turned out beautiful. It's fixed gear.

MinnFlyer

My Feedback: (4)

Retracts are a pain in the butt.

But they are so cool it's worth the trouble

vol4ever

Well, it's been a few months now & I'm re-viving the re-vive of this build. Man kids take a lot of time (but I wouldn't trade the world for it)!

This week I was able to do the first few steps of framing the wing, and I'm just getting to the wheel well part that has been a popular topic of discussion in several of the other Ultra Sport build threads I've read through. It seems to be an almost universal decision to move the retracted wells out 1 bay in the wing. I originally thought that was to allow longer gear / more prop ground clearance, but now I'm not so sure. Do I need to plan on lengthened gear mains with the move, or just simply move them out "as is"?? Also read in a couple of places where folks had just built the plane exact to the plan for simplicity's sake, and not had any problems.

What to do, what to do? Need to know quick as I hope to get back on the table tomorrow. We'll have to see how that goes. HA!

~Vol

P.S. Sorry to read about the recent passing of MinnFlyer. He had helped me quite a bit in many different threads posted over time. Very patient gentleman, even with those of us that could ask some really dumb questions. Hopefully he's flying 24x7 in cloudless conditions at that big airport in the sky. Rest in peace, bro.

prgonzalez

Vol,

I moved the retracts one bay and extended the wire for two main reasons. One, more clearance for a prop. Second, the retracts will be more separated giving more stability on high speed turns over the runway when you almost meet the end of it. (Overshoot). My US is a glider and I am still getting use to the amount of runway it takes for landing.

PRG

vol4ever

How much did you extend the gear wire? After more (& more!) reading, I'm definitely going to move the gear outwards. Still unsure about the extension. Can't decide about prop clearance versus gear strength since the longer wires will tend to bend & buckle . . . . which would be a nightmare with the gear closing up into the small wing cavity. Planned powerplant is an OS55AX that's been sitting on my shelf for ages, never used. Not sure about prop size yet, but will probably go with a minimal diameter to help with the ground clearance issues.

Hoping I didn't bite off more than I can chew with these retracts. Still not too late to go trike!! Seems odd to me that GP would release such an awesome kit with every available model size having potential landing gear issues.

prgonzalez

I extended the wires enough to have the wheel well between ribs. I did not want to cut any ribs for the well. I thought I had enough cuts for the retract wire crossing the ribs.

vol4ever

I did some measuring tonight. The gear as shown on the plans is roughly 2-3/4" in length to centerline of wheel. Moving the gear out 1 bay, and then extending enough to miss the ribs . . . I come up with a new gear length of about 4-1/2". That's an 1-1/4" extension which seems awful long. Am I missing something, or am I headed in the right direction?

kgibson4

My Feedback: (4)

Do you have your retractable gear in hand? I think it will depend on the brand of gear as to how long they must be to miss the rib. Also, I don't think some gear (Dave Brown, Robart) will fit in this wing, especially if you are moving out one bay. With the Hobbico gear that I am using, the strut ends up being 4-1/4" from the bottom of the wing to the center of the axle as opposed to 3-5/8" in the drawing. This is enough to clear the next rib with a little extra. This should give enough clearance for a 13" prop when the plane is sitting level (take-off and landing).

prgonzalez

I am using GP mechanical retracts. These retracts are made of composite material and 5/32" strut wire. I fly out of concrete runway. When I installed them, I made sure the retracts where locking on open and close. I have not had retract failures so far. Do I want a better wire? maybe, I have been thinking to install 3/16" wire from Robarts.

I am not sure how long they are, but I have a very good prop clearance when the plane is level on ground. I am using a 12x6 APC prop because the engine TH 0.75 is still breaking in.

kgibson4

My Feedback: (4)

I'm glad to hear that recommendation of GP retracts. Since this is my first experience with retracts, I was concerned about all the reports of struts bending. I will also be flying from a paved field so I hope this will be easier on the struts than the grass fields that most fliers use.

vol4ever

@kgibson -

I honestly can't remember if mine are Hobbico or GP, but it is definitely one of those 2. I know it's not the higher end Robarts. And your bottom-of-wing to center-of-axle dimension sounds about right for what I was measuring even though it is longer than what's shown on the plans. So you don't have any bending or flex problems with gear that long? I'll mostly be paved, but there are times when I'm on not so perfect grass fields.

While still in the package, my retracts look VERY long, so I was assuming those had to be cut to length. Or is it a case where the manufacturer has them packaged in what they consider to be an optimal length already? If so, my gear may be even longer than what I was guessing below . . . and maybe even enough to get into the NEXT set of ribs. Will have to look a little deeper tonight. Didn't even have those in front of me. I was just playing/sketching on the plans at the time.

I guess it would be smart to have those out while playing with the pencil. [&:]

prgonzalez

The wire comes in very long. You have to cut to the length you need.

kgibson4

My Feedback: (4)

vol4ever,

The Hobbico retracts have a metal main body while the GP body is composite according to prgonzalez. I think they all are supplied with extra long struts to fit any application. Replacement struts are available if you ever need to lengthen them.

I have not yet finished my US 40+ so I'm crossing my fingers that the 5/32" struts will hold up. Prgonzalez has my hopes up.

Looking forward to some pictures of your progress.

kgibson4

My Feedback: (4)

Here are a few pics of some changes I made to the build.

The retracts are moved out one bay and one more bay will be sheeted.

The elevator and rudder servos were moved to the hatch area to help compensate for the added weight of the OS 70 Surpass.



Hmm. The pictures didn't download for some reason. Yup, my mistake.

vol4ever

Outstanding pics. I logged on to post a different message, but your pics almost answer it. I'll go ahead with my planned message just for conversation's sake. I uploaded a couple of scans from the plans that I hope show up?? Haven't done that in a while.

The original plans show the gear mounting tight to the left side of W-4. What's odd to me is that the gear looks much longer in the fuse pic than it does in the retracted wing pic. Must just be the perspective difference. Without getting into the ribs, I see 2 potential solutions:

A) Move the gear mounting to the right side of W-4. My quicky measuring at the building table appeared that plan would win up with gear of almost the exact same length once it was positioned to miss the ribs. Overall gear stance increases by 3" (1.5" out per side).

B) Move the gear mounting all the way out to W-5. Measuring this option appeared to lengthen the gear by 1.5" when the wheel position was adjusted accordingly. Overall gear stance increases by 9" (4.5" out per side).

However, from your pics it look like you moved the gear mounts out TWO bays which looks to keep the gear a bit shorter, but widens the stance bigtime. Did you have to relocate the servo mounting tray? Your pic is the opposite wing from the plan, and my brain has trouble performing the mirror image!

How did we ever build a plane without the internet?? [8D]

EDIT: I was wrong. After further review, it looks like you used option B exactly as described. Given that lengthened gear, I wonder how hard it's going to be keeping it straight enough to go back into closed position after a hard landing or 2? Regardless, your wheel well framing looks awesome.

kgibson4

My Feedback: (4)

I think that the added length of the strut depends on the design of the retract you are using. If the pivot point of the strut is farther outboard in the retract, you will need a longer strut to get to an open bay. With the retracts I have I am ending up just 5/8" taller than stock.

Keep in mind that many people have built this plane with the wheel directly on a rib, with no adverse effects at all. You can build to your desired finish height and not have to worry, I think.

Keep in mind that the bottom of the wing has some dihedral so as you move the retract outboard it rises relative to the fuselage centerline.

vol4ever

I have the GP 0.40 retracts:

http://www3.towerhobbies.com/cgi-bin...?&I=LXUY32&P=7

The way they actuate, the gear would need to be lengthened by 1.5" or so to clear ribs, so mine must be different from yours. My gut is telling me to go with the W-5 mounting, extend the gear by roughly 1/2" over what is shown on the plans to allow for a bigger prop (plus account for the dihedral . . . good catch!), and then just modify W-4 ribs as necessary.

kgibson4

My Feedback: (4)

I think that's a good plan. You should have an easier time mounting the GP retracts. The Hobbico took some carving of the mounting blocks and shimming to clear the top sheeting.

I am going to set up flaps on the inner 1/3 of the aileron; another MinnFlyer suggestion. This requires that the aileron servos move outboard also. I will be using mini servos (HS-225) laid on the side under hatches for a cleaner wing.

vol4ever

Measurements done, ribs trimmed, and gear installed in first wing. Like you, I chose to do everything BEFORE sheeting. How did you make that nice circular wheelwell? Think I'm gonna do that and then paint the while area with flat black epoxy for protective purposes. Still haven't quite figured out how to make the sheeting be neatly trimmed around the gear area. That may be a trick.