RE: Retractable undercarridge instalation in a RTF
 

Scottrc
glad you liked the project, will detail the whell well installation once I get there, my main objective was to ensure that the loads from the wheels are transfered into the main spar of the wing and not to the ribs hence the replacement ribs and doublers and treberlers where all in plywood, the spar webs were cut out to allow the ply ribs to overlap with the existing ribs left in the D box and then replaced. its only when you start thinking about this to put in writing that you realise you do some things automatically and not neccesaraly explain it all. I may have to write up a complete installation guide at the end, does anyone think this would be helpfull?
keep looking.
Mike

RE: Retractable undercarridge instalation in a RTF
 

Ok
christmas and new year now over, will get back to finnishing the PC9 retracts begining of next week thats the 9th January, hope you are all waiting with eager antisipation, I know I am.
Mike

RE: Retractable undercarridge instalation in a RTF
 

WHEN YOU FLY LET ME KNOW IF YOU LOST AND FLIGHT TIME BY CHANGING TANKS.... BTW NICE WORK I HAVE THE SAME MODEL AND HAVE WANTED TO DO THE SAME.......

RE: Retractable undercarridge instalation in a RTF
 

WILSONC81

The original tank used was a Graupner out of a 300L Leki with no makings to say what the capacity is, the supplied tank from Seagull is a lot smaller I would hazard approx half the size again no markings, the now installed square tank is larger than both in capacity, therefore I do not envisage any shorter flights, except that with the undercarridge retracted it should fly faster for a given throttle setting therefore I may run out of fuel before the PC9.
What do you have in yours?
Mike

RE: Retractable undercarridge instalation in a RTF
 

To everyone monitoring this site

I'm sorry I have not posted recently, but a medical problem has curtailed building work at the moment, I am only able to type and surf, hopefully back to full fettle soon.

Mike

RE: Retractable undercarridge instalation in a RTF
 

Hi all

Just received the four blade spinner from True Turn will put it on with the prop and post a pic as soon as my camara batteries charge.

Mike

RE: Retractable undercarridge instalation in a RTF
 

Cant wait to see the final pics!

Crash

RE: Retractable undercarridge instalation in a RTF
 

Crash

Thanks for the encouragment, back in harness and will complete soon meanwhile the pics below show the four blade prop and true turn spinner, ground clearance problem solved if the prop is man enough, blades look a bit narrow but I suppose in total area with four blades they are not.

Mike

RE: Retractable undercarridge instalation in a RTF
 

Ok here we go again

Pics below show the Wheel well being constructed,
glue in a floor for the well of the same thikness as the original rib caps.
choose a pot of some kind that is of a diamiter that will give sufficient clearance around the whell and cut out two pieces of balsa accordingly.
Glue in one of the pieces on top of the floor in the position predetermined by the length of the undercarridge.
Take a piece of 1/64 ply and cut out to form the wall of the wheel well, make it overdeep to allow sanding down after flush with the top sheeting. Biro in position to show how I sized the piece of ply, just run it round the edge and it will be proud by the half the thickness of the biro.

More latter.
Mike

RE: Retractable undercarridge instalation in a RTF
 

Herewith the latest

Pics show top sheeting in place, the ply wheel well needs to have a sub support glued to it too enable the top sheeting to have something to glue too. The top sheeting is the other piece of balsa cut out in the previous stage, infill pieces of balsa are variously glued around the opening to support the covering, which has been peeled back to enable sanding and filling. Extra support for the retract bearers was glued under same 1/4 sq used, also to the back of the bearers to support balsa sheeting.
Other pic shows the retract temp in position to ensure clearance, next job bend up the legs and re-cover.

RE: Retractable undercarridge instalation in a RTF
 

Looking good Mike. I bought a Tru turn spinner for mine. If you have a dremel tool and some buffing wheels, it only takes about an hour with good metal polishe to make it look like a mirror. Even unpolished, it looks better than the red plastic one. Thanks for posting your modification
John

RE: Retractable undercarridge instalation in a RTF
 

da50ex

I thought I would post a copy of our last correspondance from the YS63 site, as it would interest anyone thinking of doing this conversion. John and I had been disscussing the merits of extending the nose of the Seagull PC9 to allow a full length retract leg to be used. below is my reply to him.

John

It would need to be extended by only approx 25mm sorry 1" to allow a full length leg to retract without hitting the wing LE, the problem with a bigger engine is going to be getting the cofg in the correct place exacebated by the retracts etc: This may not be a problem with a 2S needs carefull measurements, if you used a bulkhead mounted retract unit as I did the whole thing would be easier, by just building a 1" box out from the existing firewall to mount the retract and engine mount. If you actually made it a full fusalarge extention then you would not have the problem of extending the cowl. You may be able to get over the weight problem by rear mounting the servo's, one either side for the elevator and one underneath for the rudder with a close loop linkage, now this has wetted my taste buds as well, (say slowly) must buy new kit.

The best answer would be to put in an AXI 4120/18 on 6S1P LiPo's turning a 14x8 now thats a thought that I must consider.

Thinks! 55amps at 20volts taking into consideration volts drop is 1100watts divide by the weight of aircraft sy 61/2lb with batteries would give us 169.2watts/lb thats 3D performance, this will have to be considered further.

Mike (now excited)

RE: Retractable undercarridge instalation in a RTF
 

Ok Chaps

Finaly finnished pic shows air tank installation under the servo tray, with the air control valve mounted above with a didi servo control, air in one way valve positioned on the side ot the fus, just run up the engine in my field which is very rough pasture, on some taxi runs the prop hit the grass tussocks, my flying field is in better condition i.e. flatter, hopefully this will not happen, I have changed the wing mounted wheels for smaller items to increase the prop clearance even more, will fly tomorrow and report back.

Mike

RE: Retractable undercarridge instalation in a RTF
 

Mike,
Good lock and don't forget your camera
John

RE: Retractable undercarridge instalation in a RTF
 

Well chaps not happy yet.

I have the fastest ground attack PC9 in existance, runs round the grass strip at warp factor 10 but not enough to lift to bring the wing to a positive incidence, hand launched it was fine with the retracts up looked oh so good, but is not the point of the exercise, next installment extend nose to increase clearance between wing and firewall hence leg length? or any suggestions?

Mike

RE: Retractable undercarridge instalation in a RTF
 

Just a couple of pics showing the undercarridge in up and down postion, it just shows how clean it becomes with the wheels up.

RE: Retractable undercarridge instalation in a RTF
 

Ok

I think I have found a partiall solution, the nose bulkhead retract has a lower pivot point than a flat mounted retract unit, (see pic) it also has a longer distance from the bulkhead mount too the pivot point (see pic), these will enable the leg length to be increased by approx 17mm, by moving the retract unit forward towards the back of the engine the maximum without touching the carb, I can get another 9mm this adds up too 26mm or 1mm over an 1" I now need to trial assemble to see if I can get a more faverable incidence on the wing, further progress will be posted.

Of course non of this applies if I took out the four stroke and replaced it with a two stroke, you can position a 2S far enough forward to enable the retract unit to sit half inside the engine compartment, which would give sufficient leg length.

Mike

RE: Retractable undercarridge instalation in a RTF
 

Further investigations into the nose retract broblem, the bottom hatch to the nose retract if made out of 1/4" ply the retract unit can be fixed to this, in turn this moves the retract even further down and overall I have increased the leg length by nerly 30mm or a 11/2" which is enough ureka, will start to modify the installation tomorrow. Keep watching.

Mike

RE: Retractable undercarridge instalation in a RTF
 

Mike,
It looks great, If you are able to increase the length of the nose gear perhaps you can put a different prop on it. The 4 bladed prop looks great, but I've heard that you lose something with them. I finally got my PC-9 flying again. Flew great, but our feild is too soft. Also heard some flutter on the 3rd flight and found the torque tube in the elevators loose. An easy fix. I'm also ressurecting an old Skybolt for a 2nd plane, so I don't know when I'll get to my modification. May be a couple of months

John

RE: Retractable undercarridge instalation in a RTF
 

Further works

Pics show the bearers out of square on purpose, in place with front supports and cantilever past the firewall, second pic shows the retract in place and reason for the out of square to miss the coil on the leg.
Final pic shows the engine placed in postion and the trimming needed to give clearance to the carb, some of the metal from the retract can be removed without compromising the integrity of the unit.

More latter on how much I was able to increase the leg length by.

Mike

RE: Retractable undercarridge instalation in a RTF
 

Well I now have it all in postion and I do have an extra 30mm, the wing is at almost 0deg incidence and the tailplane is at a positive deg of incidence, this must make a big difference, I am now confident that it will ROG will post more pics as soon as it looks presentable, detailing the last mods and the new steering that is only in my mind at the moment.

Mike

RE: Retractable undercarridge instalation in a RTF
 

Ok Chaps

Further pics show bearers now fuel prooffed, installed retract with cover fitted, and the mods done on the retract to get just that little bit more room. First thought on steering did not work will have to re-think the installation, thoughts now are a servo flat mounted under the retract unit with cables in guides up to the front of the retract that will work but needs the servo raised off the floor to allow the arm to move sufficiently, this servo is on a Y lead to the rudder and obviously has to keep on working whilst the leg is retracted.

Mike

RE: Retractable undercarridge instalation in a RTF
 

The steering servo problem has been sorted, I used one of those glider aileron wing covers with the guide cut off to mount the servo on the top of the tank cover, small piece of brass tubing to act as a bearing as shown in pic, the servo is a Voltz metal geared high tourque mini, overkill I know but it was available, for those of you who may have wondered how the steerable nose leg stays straight when being retracted look at the second pic it shows the pin attached to the plastic unit that fits over the retract bearing block, in turn this is inserted into the steering arm, flexes when being steered.
Hope thats clear look at the pic and I think all of you could work it out.

May get a chance to fly tomorrow if so will report back.
Forgott to put cammera into macro mode, hope second download is clearer.
MIke

RE: Retractable undercarridge instalation in a RTF
 

Well I just put the plane together and I have 2deg nose up incidence on the tailplane, this is approx the same as the original so should be OK, the overal weight has worked out at 6lb 10 onz with the OS70 on board, this is all looking much better, will fly tomorrow if weather permmits, ever hopefull.

Mike

RE: Retractable undercarridge instalation in a RTF
 

Well all

Eureka it works, oh how it works ROG retract undercarridge pull full up to vertical half roll on the upslope pull full elevator, half inside loop vertical down and pull another half loop to the horizontal and downwind pass at 6' off the deck looked superb with no undercarridge to spoil the view, seems to be smother and faster, could be an illusion as its so clean, first flight over 10mins to a dead stick extend undercarridge, plenty of speed knife edge turn and dump on patch as I have not tested the stall yet.

Second flight, get some height test stall with and without undercarridge definate difference in stall speed and responce at and in the stall, with the u/c retracted the stall is deeper and takes more height to recover, to be expected with the cleaner profile I suppose, as the plane accelerates faster. Next try slowing down and then extending the u/c not much of a trim change but a definate increase in the decent rate, all good stuff.

Landing with power on was an anticlimax, it just slowed down to the point of stall approx 6" off the deck very nose high kissed the grass with the mains and lowered itself onto the nose leg. Two other chaps at the field are now interested in building a copy so we can go formation flying, now that is going to be fun if not full carnage .

Next visit to my field with decent weather I will vidio and post.

Extreamly chuffed
Mike