drube

I'm still running the stock LG also. On my 3rd set..lol Still makes me nervous on landings. I just don't trust them that much.

j301

My Feedback: (12)

Thats why H9 chose a Navy scheme, 'cause the gear make the plane wobble like a drunken sailor...

da Rock

The picture and diagram of the Sonics shows more than half the mechanism forward of the gear when extended. The gear on F4U and F6Fs are hinged just back of the leading edge of the wing. It looks like installing those things close to the LE would be impossible. There is even what looks like a motor projecting .7" forward of the main structure.

Has anyone got a picture of the Sonics installed in a Hangar 9 Hellcat?


OK, I measured the holes in the H9 wings for the Corsair and Hellcat. There are bulkheads in the holes where that motor would project. Installing the structure shown in the Sonic diagrams as far forward as possible is going to move the gear's axis of rotation maybe a half-inch aft. WAGuess is the Sonics could be fit in, but give away some of the forward footprint they offer.

Picture anyone? Used them yet?

drube

Wouldn't that cause more nose overs?

j301

My Feedback: (12)

You know the more I think of it, I do believe that it was this thread where I saw these. They must be counting on the 100 degree to put the wheels fwd enough. I dont think anyone, that I remember, used them. They were going with the plastic ones from PW RC: http://www.pw-rc.com/product_info.ph...oducts_id/2381 . I thought about it but I think Im a bit too heavy for these. He has them on ebay as well.
I have siera's I was going to use but didnt want to chop up the main spar, and ended up using them in a 140 size p40 anyway.

da Rock

The farther aft any gear is placed, the farther back the wheels touch the ground and the closer that point of contact is to the CG. So yes, it would.

Those gear rotate 100degrees in order to put the footprints farther forward. Then they take some of that back with design decisions that're going to have a lot of installations result in putting footprints even further back. It's a puzzle why they chose to place the motor sticking forward and the trunion farther aft. The forward bulkhead in the retract well in at least one of the H9 wings is ply. Putting a hole into it for the .7" of the motor will not be easy.

drube

Thanks.

pjwright

I scaled the Sonic Electric 100-degree retracts from their drawing - the motor was drawn shorter than scale, for example. The enclosed jpeg (which must be enlarged 153% due to RCU compression) is pretty close to exact 1:1 scale. I cut out the templates, and this thing is practically a drop-in. The motor does extend 0.7" in front of the retract housing, but there doesn't appear to be any critical structure (e.g. spar) in front of the existing mechanical retracts. You have about 1" before you'll hit the back of the leading edge. There's a plywood plate in front of the H-9 retracts that must be Dremeled out to accept the retract motor. I do believe I'll order a set...

PJ

da Rock

I'm baffled by what you say. If you haven't got a set (you say: "I do believe I'll order a set...") what did you base your correction of their drawing on? Just using their pictures of the units, it looks like the motor projects half the length of the structure. That would be about 21 mm.

BTW, I did some scaling against their drawing and it appears they designed the rotational axis aft almost an inch from the front of the primary structure. Time to go down in the shop and measure how far aft the Lado and WingSpans placed their axis.

...
OK, direct measurement of the Lado and WingSpan units shows the axis to be:
Lado = 20 mm aft
WingSpan = 18 mm aft

so it looks like the 26.4 mm aft Sonics won't move the footprints but about 1/3" worst case. That is, if you take the trouble to fit them. Grinding out a hole for the motor will be a make or break decision for a lot of people.

da Rock

BTW, using 100 instead of 90 degree gear on my Hellcat moves the footprints 1.15" forward.

Using the Sonics would get you just a touch under 1". The difference between makes would be of little importance. I look forward to hearing what you find after grinding out that ply... and using those units...

Man, it really looks like designing good gear for model airplanes is somewhat of a long reach for the model industry.

da Rock

Also, measuring the Hellcat wing shows about 40mm of "room" forward of the Lados that are presently in that plane. I've got no idea how big a leading edge is hidden in there, but doubt it'd take up more than half space behind that plywood.

Good luck and let us know how your installation comes out.... or goes in, that is. Looking forward to hearing the details. That Sonic might be closer to what we've needed, and might be all we get anytime soon. That is, if it can be installed and then works.

pjwright

I scaled the drawings based on the dimensions given so they came out 1:1, from which I cut out the template as shown in the photo.
Placing the Sonic unit at the front of the mounting rails creates an offset of roughly 3/8" aft of the Hangar 9 mechanicals.
100-degree deflection of a 6-inch strut results in a forward displacement of 1.06" ... a net gain of about 1" toward the leading edge, still leaving the axle about 3/4" aft of the leading edge.
Not perfect, but better than a 90-degree retract ... and regardless, I intended to convert to electric. So this looks like a viable solution. It'd be nice if H9 would produce an E-flite electric unit for their Hellcat ... but I'm not holding my breath.

PJ

irocbsa

My Feedback: (12)

Guys, please be wary when ordering those retracts. As da Rock knows, I've been on the same quest as he has to find reliable electric retracts that I don't have to remortgage my house to buy. I've wasted my money multiple times, and my first painful foray in the world of the rip off was the set that is being mentioned above. They are technically "RC Lander" gear but the are sold under multiple names with the same crappy results. They may be labeled as "all metal" to imply stength, but they are far from it. I went through three replacements due to the motors freezing midway through the travel, case fractures on smooth landings, and circuit board failures. They are completely incapable of consistently lifting even the lightest of tires and struts that I could find. I finally gave up. Even if you do get a set that works for more than 10 cycles, the slop in the gear is so horrendous that you will have a helluva time getting down the runway. I too thought that the price point and "all metal" construction couldn't be beat and go lured into buying a set. Please don't make the same mistake. Unfortunately, there is still a huge void in the market while we wait for someone to come out with an affordable and reliable set of rotating electric retracts.

dawhale

My Feedback: (20)

So is it safe to say Robart air operated is still the bench mark? I too want electric for my Hangar 9 Hellcat. It hangs in my gaurage waiting.

Chad Veich

My Feedback: (60)

The Sierra Precision pneumatics are the bench mark in my opinion. I have had half a dozen sets of the Robart units and I've had good luck with them. I'm currently flying them in my 1/8 scale Hellcat. However, the Sierras are substantially sturdier and with less slop in the down and locked position. I'm building a second Hellcat now that will have the Sierras rather than Robarts.

dawhale

My Feedback: (20)

With the Sierra Precision do you have to cut the main spar in the Hangar 9 Hellcat? Like to see some install pictures if someone following this forum has done it.

Thanks

Chad Veich

My Feedback: (60)

I put Robart units in a Hangar 9 Hellcat and while it did take a few simple mods I don't recall cutting any spars. The Sierra units are just a fraction wider than the Robarts but otherwise mount the same so I don't see any reason why it would be any different for them.

da Rock

Here is a picture of the installation in my H9 Hellcat. It shows the U shaped brace I made with carbon fiber sheet to reinforce the spar. Any retract mechanism with a significant power section that projects aft from the main framework will encroach on the spar.

The brace was made up by sandwiching CF between plywood. It extends under the wing's bottom sheeting and is epoxied to the spar.

Chad Veich

My Feedback: (60)

The Robart units are bottom mount rather than top mount so I remember having to lower the gear rails down near the bottom wing skin. I didn't recall cutting the spar but, after looking at da-rock's pic above, I must have as the Robarts definitely have a significant amount of mechanism which protrudes aft. Don't recall exactly what I did to return the strenth to that area but the wing didn't fold up so I must have done something right! Keep in mind that even though you may have to cut the spar you will be tying it back together again as soon as you bolt the retract unit in place.

RBean

About four years ago when I first got my Hellcat flying, I discovered that the stock retracts were worthless, at least with my flying skills and off grass. I think I had three or four flights with them. I installed Century Jet air retracts. They are listed as 93 degree retracts. I had to move the mounting rails down and cut a hole through and then reinforce the spar. So far they have worked ok. They get loose after a year so at "annual" time I take them out and do my tightening up procedures. The only problem is I had to mount them at an angle to get some forward rake. Now they don't retract all the way into the wing. Not that I can tell when its flying. I would like to replace them with 100 degree electrics, both those available don't seem to be worth the cost and trouble. Here are some pictures if I can find them. This plane has leabout 240 flights on it now.

ihaveahellcat

I got a set of LADO's for my Hellcat and they fit perfectly, I did cut the top spar just so I could fit the Hangar 9 Oleo's in and they would be flush. After I cut the spar I did reinforcement it with three pieces of 1/4" (I think) ply.

w1nd6urfa

My Feedback: (4)

+1
The RC Lander "metal" is low quality cast aluminum, won't take anything larger than a 3lbs foamy.

I recommend Lado's, I still have a set I bought off Doug's garage back in 2009. It;s been used on a BH P-40 and now on a [link=http://www.rcuniverse.com/forum/m_1141201/mpage_100/key_/tm.htm]H9 Corsair[/link], they are machined aluminum really solid!

Nick

har28

Hallo, i have read this thread from the beginning and it was very helpful for the assembly of my hellcat. I have the stock retracts and they seem well made so I'm gone leave them from now and i will see after the maiden flight !! I use stock retracts with spectrum A7000retract aircraft servo with servo rate reducer - 6 seconds by Dionysus and they work really nice and very scale here is the video how they works

http://www.youtube.com/watch?feature...&v=1OYkcQIWmLE

har28

Here is another one from the assembly

http://www.youtube.com/watch?v=fM-iP...feature=relmfu

RBean

I was having a great time a couple of weeks ago flying the Hellcat. It was running great (DLE 20) the wind was calm. I decided to do some rat racing down low. On on pass I thought I was too low. Didn't want to caught a wing in the top of the corn. So on the next pass I was a little higher and hit a high wire. I didn't think the plane was out that far. It totalled the Hellcat. Severed the right wing and left a debrie trail 30 yds long. The good part is all the hardware survived and the engine has already been installed in another plane. I might get another H9 Hellcat some day as the Century Jet air retract survived undamaged as best I can tell. This one had flaps where were really effective so that will be an effort to do the flaps over, but I think I can make them better next time. I just have to stop doing stupid things while flying.