Retractable undercarridge instalation in a RTF
 

Hi to all
I'm going to install a retractable undercarridge as a winter project in a ARTF the aircraft in question is the Seagull PC9, will this be of interest to anyone? As the whole purpose of this is to clean up the profile in flight I may make this into a tail dragger as well heritic I can hear you say, but this will make the subject much easier to fly off grass, any comments gratfully received.

When I came back from Univercity I was amazed how much my partents had learnt.

Mike

RE: Retractable undercarridge instalation in a RTF
 

Go for it Baldy. We'd love to see pics!

RE: Retractable undercarridge instalation in a RTF
 

I like to think that my peers gave me the call sign because I used to stay up longer in my glider (full size) than they did, but I think it was because I am folicly chalanged.
I will post pics as the installation of the retracts progres's, I'm also thinking of doing the same to my Arrow Tiger.
Mike

RE: Retractable undercarridge instalation in a RTF
 

Ok guys
The original wheel position in the wing is too far back for good take offs from grass, therefor first decision is to move the undercarridge forward (see pic) this will entail abandoning the original bearers and installing all new, Second decision the nose wheel is too long to fit in the bay in front of the wing, this will entail shortning the leg and reducing the ground clearance at the moment there is 2 1/2" of clearance with a 12" prop so this should be feasable. next installment what retracts pneumatic (space problem) mechanical (two servos, third for stearing?). will start to cut soon.
Mike

RE: Retractable undercarridge instalation in a RTF
 

I've seen installations with three gear hooked to one retract servo--not easy to setup, but it is possible. The steering will get you, though. I don't see anyway around a separate servo for that--pull pull is the only way I know of around it. I've not setup trike retracts, but I've done some main gear retracts--both pneumatic and mechanical. Pneumatic is definitely the easiest to setup, IMO, but you have to have room for the tank, and valve. This is sometimes difficult to find, but that looks like a fairly thick wing--put the airtank in the wing! If it isn't a scale plane (I don't know anything about the plane at hand), then I'd definitely change it to a tail dragger and be done with it!

RE: Retractable undercarridge instalation in a RTF
 

2slow2matter
thanks for your input, the only air tanks i have or can find are about 1 3/8" in dia, this is thicker than the wing and bigger than the space between the servo tray and the underside of the wing, I must admit that I prefer air up spring down if I can fit it, but if looks as if I'm going to have to go to a mechanical system, tail dragger is an option but it will mean cutting into the D box of the wing due to c of g and spar positoning, I think in all probability I will go mechanical and stay trike, just downloaded the Eurokit catalog whitch has a lot of possibilities in it.
Will keep updating.
Mike

RE: Retractable undercarridge instalation in a RTF
 

Further thoughts, easy solution tint the canopy and install all the gubbins under it, mass's of room.
Mike

RE: Retractable undercarridge instalation in a RTF
 

To anyone browsing
I have decided on the Robart 510 series of retracts, but unfortunatly they are unavalable over here, can anyone help, I need:
Robart #525RS
Thanks in anticiaption
Mike

RE: Retractable undercarridge instalation in a RTF
 

Hi all
Pics show the mods so far:
First pic shows the wheel in position using the oblong tank in place, other pics show original wheel strut above original stearing gear, and one with it laid in place, room enough, other pic shows original tank supplied with the PC9 and not used, the Graupner tank used with the standard fixed gear, and the oblong tank (330cc) which gives room for the retracts, will post more pics when I install the retract, it looks as if I will have to cut the firewall and install the retract on the engine side of the engine former possibly with a packing to get sufficient room for a proper length of leg.
Mike

RE: Retractable undercarridge instalation in a RTF
 

Hi all
Looking at the pics from right too left:
Pic one shows the mods to the original firewall to accomadate the retract unit (Sping Air) note steering slot recess.
Pic two shows the secondary bulkhead used to get the retract as far forward as poss to allow sufficient leg length.
Pic three shows the retract in place
Pic four shows the steering arm in its recess on the original firewall, neccessary on retraction.
I'm just epoxying the firewall and secondary bulkhead together once done will progress with build.
Mike

RE: Retractable undercarridge instalation in a RTF
 

More progress
Pic shows false floor over tank, due to the restricted space for the nose leg will have to go to a 3 or 4 blade prop to give sufficient ground clearance, should not be a problem with a 70 4s that I am using sorcing the spinner may be a differant matter though.
Mike

RE: Retractable undercarridge instalation in a RTF
 

Hi to all and a mery christmas and a happy new year to all who read this.

Pics show final installation of the nose wheel retract, am sourcing a 10 x 7, 4 blade prop to use this gives me an 1" further ground clearance for the prop, will start the wings next, some feed back from anyone would be nice.
Mike

RE: Retractable undercarridge instalation in a RTF
 

What more can we say but "Beautiful!"

Keep it coming!

RE: Retractable undercarridge instalation in a RTF
 

Nice work BE!

RE: Retractable undercarridge instalation in a RTF
 

Thanks guys I thought I was talking to myself.
Mike

RE: Retractable undercarridge instalation in a RTF
 

For all you guys with a Seagull PC9, don't worry about your wing mounted undercarridge it was a swine to get out in the end I cut out the ribs and will have to make new see before and after pics below.
Mike

RE: Retractable undercarridge instalation in a RTF
 

that looks clean, can't wait for final pics.

RE: Retractable undercarridge instalation in a RTF
 

Hi all
Some progress, slowed by stuffing my Arrow Tiger at the week end, finger trouble too slow and too low, minimal time to repair, intermediate bulkhead and tank floor only.

Pics show ribs cut out with doublers and treberlers? prior to installation.
Second pic shows them in place but not glued prior to final shaping, so don't be too critical, note slot for aileron lead and floor installed for wheel whell, more pics soon.

RE: Retractable undercarridge instalation in a RTF
 

Great job Mike!
And a Merry Christmas and Happy New Year to you.
I am thinking of putting retracts in my next project a Great Planes Chipmunk.
Your project has given me inspiration.
Keep up the good work.
Cheers.
jef

RE: Retractable undercarridge instalation in a RTF
 

awsome mike
good job, cant wait to see the finished product

RE: Retractable undercarridge instalation in a RTF
 

Thanks for the encouragement, its appreciated
More progress, ready to re-cover one side, will start on the other side asap, don't think I will post anything on the other side as it will be mostly the same, have a few problems to solve as too angle of attack of the wing when on its wheels, prop clearance, round out of aircraft at take off i.e. if the wheel legs become too short there will not be enough clearance for the tail to rotate, if the wheels are too long the angle of attack will be shuch that a high speed would be neccesary to enable rotation, all of this is dictated by the nose leg, which is a fixed criterier due to the length possible which is dictated by the space between the firewall and wing, speed would not be to much of a problem on pave, but I fly off a small mown grass patch, this continues to be an interesting exersise.
Mike

RE: Retractable undercarridge instalation in a RTF
 

One side 100% other side next.
Mike

RE: Retractable undercarridge instalation in a RTF
 

Had not related to all that I am using spring air retracts, the air tank is under 1 1/2" in dia therefore will fit in the servo bay under the wing, noted I did not detail the wheel well instalation when constructing the left hand side will remidy that when carrying out the right hand side, thoughts that have now come to mind are should the servo wire's and retract air line be in the wheel well or running around the outside? prudence made me put them through the well to enable future maintenance, but now I think this may have been a mistake, will look at this on the installation on the left and give it some thought as to route within a tube of some kind. what do you all think?
Mike

I do not know Prudence and have never been anywhere near her. and I was not with her when I got home late last night, honest.

RE: Retractable undercarridge instalation in a RTF
 

I have now taken apart the finnished side to allow the removal of the pressure pipe and installation around the outside of the wheel well, much neater, I have also come across a problem with the leg installed because I bent the wheel axel on the wrong side of the coil I have moved the wheel approx 1/4" down into the well, I need that 1/4" for the whell to sit in so that the retract locks, new leg needed as I do not think I can re bend a piano wire leg through 180 deg's,may have a go just to see if its possible.
Mike

RE: Retractable undercarridge instalation in a RTF
 

Very good project. Thanks for giving us the pics and details on how you did this. I have wondered about adding retracts to a few ARFs such as the Tower KAOS, Goldberg Tiger, or GP Super Sportster. I have done retracts in the kit versions, but wondered how to tackle an ARF.

Scott