PST F-84G Build Thread
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RE: PST F-84G Build Thread
I miss that plane, was a pain in the backside at times but well worth the effort. Thanks for letting me experiment on your baby!
Chris
Chris
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RE: PST F-84G Build Thread
Hi Steve,
Yes, we are seeing the ram-air resistance on customers' F-84Gs fitted with main gear doors. On our F-84Gs, we made spring-loaded swivel gear doors (for scale) that coincidentally neutralized the ram-air effects and we also used 120+psi pressure which helped to take the gears in. The 2nd F-84G has the doors removed due to some damages and not because of the ram-air. However, we are designing a new and larger retract cylinders to get more pulling strength. When this new design is finished, we will send them to all F-84G owners.
Regards,
Kraivuth S.
Yes, we are seeing the ram-air resistance on customers' F-84Gs fitted with main gear doors. On our F-84Gs, we made spring-loaded swivel gear doors (for scale) that coincidentally neutralized the ram-air effects and we also used 120+psi pressure which helped to take the gears in. The 2nd F-84G has the doors removed due to some damages and not because of the ram-air. However, we are designing a new and larger retract cylinders to get more pulling strength. When this new design is finished, we will send them to all F-84G owners.
Regards,
Kraivuth S.
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RE: PST F-84G Build Thread
Ok, here is how far I go tonight. just need to figure out a way to bolt the lower tank in place and build header tank mounts. Once all that is done, I can start dumping components in and moving them around to work the CG as I bulid.
Chris
Chris
#107
RE: PST F-84G Build Thread
Hello All,
There is now some PST F84G in flying condition.
Could you please confirm me the dry weight of this plane ? And the amount of nose lead for correct balance if required.
Thanks.
Stéphane
There is now some PST F84G in flying condition.
Could you please confirm me the dry weight of this plane ? And the amount of nose lead for correct balance if required.
Thanks.
Stéphane
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RE: PST F-84G Build Thread
Here is the last of the fuel system install. Took some shoe horning to make sure the canopy mechanism would clear everything. Starting to lay out radio and turbine components now to see what I am working with then it is on to getting rid of those nasty hatch latdhes and coming up with something that is concealed, once that is complete, it is on to the wing pylons and releaseable ordinance!!!!!
Chris
Chris
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RE: PST F-84G Build Thread
Well, herre is how th ebatteries will be installed. I removed PSTs stock mounting trays to do my own thing to get the weight transffered to the front.
Chris
Chris
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RE: PST F-84G Build Thread
Here is tonights progress, wanted to get the power distribution figured out. I have five more leads to build and install and then I can start tinkering with turbine components followed by pneumatics and fuel system.
Chris
Chris
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RE: PST F-84G Build Thread
Chris,
I love what you did to the nose compartment. I probably wouldn't need so much "catfish lead" if I would have placed my batteries where you did []
Finally modified the gear plates and locked them in with CF plates. She's ready for another voyage -
Steve
I love what you did to the nose compartment. I probably wouldn't need so much "catfish lead" if I would have placed my batteries where you did []
Finally modified the gear plates and locked them in with CF plates. She's ready for another voyage -
Steve
#120
RE: PST F-84G Build Thread
ORIGINAL: samo
Finally modified the gear plates and locked them in with CF plates. She's ready for another voyage -
Steve
Finally modified the gear plates and locked them in with CF plates. She's ready for another voyage -
Steve
Roy
#121
RE: PST F-84G Build Thread
Thank you so much for this build thread. I've built models for years and am still nowhere close to being able to produce the quality of workmanship that you display. I am in awe! The pictures always teach me something new to attempt even in my sport models as far as setup and running wiring. The tidyness of all that wiring is to be commended. Keep posting and I'll keep wiping my chin!
On a side note, I was ADAF as a mechanic on B-52's and B-2's. I was never stationed at Fairchild, but did a few TDY's there and always enjoyed it. I even got to spend some time out in the mountains for some training I needed for a crosstrain into helicopter flight engineering.
On a side note, I was ADAF as a mechanic on B-52's and B-2's. I was never stationed at Fairchild, but did a few TDY's there and always enjoyed it. I even got to spend some time out in the mountains for some training I needed for a crosstrain into helicopter flight engineering.
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RE: PST F-84G Build Thread
TJR1, Thanks for the compliments! I will be hitting it pretty hard over the next couple of days so I hope to have some pictures updated. I will definately be revisiting the main gear plates and am istalling 635 Robarts. Steve, would like to see what you did to the plates so we can compare notes.
Chris
Chris
#123
RE: PST F-84G Build Thread
ORIGINAL: Stratotanker
I will definately be revisiting the main gear plates and am installing 635 Robarts. Steve, would like to see what you did to the plates so we can compare notes.
I will definately be revisiting the main gear plates and am installing 635 Robarts. Steve, would like to see what you did to the plates so we can compare notes.
Installing the Robart 635 RS is a wise choice. In fact it is the only possible choice.
The original mechanism is totally useless. I have tried to modify it to make it work but the pistons are leaking...
So I droped this project after about 30 hours of hard work and tried different mechanisms.
300 dollars later and after the wise recommendation of Barry, I tried the 635 RS. Bingo !!!
Big pistons, big trunion arm. Oversize square brass trunion slides. The heavy main gear is retracting at 60 PSI vs the original requiring 160 PSI to merely go up...
After 2 months of fiddling around I know that I now can retract the gear in flight !
The main gear plate design is amazingly wrong. Beginners mistake. Unbelievable.
The torsion effort induced by the main gear will almost certainly unglue the plate at the first hard landing and ruin the wing sandwich.
Here is my design modification:
No need for carbon fabric reinforcement: The idea is to connect correctly the front plate to the oversized gear ribs.
The same plywood reinforcement goes on the outer rib. It is a bit difficult to Hysol due to the room restriction.
Concerning your work, congratulations. It is beautiful.
Just one remark: keep it light. A scale F-84G will easily hit the 45 lbs barrier and need a 160 N class engine.
Another remark: the cooling design at the rear of the plane is minimal: I have recorded inner temperatures in excess of 300°F in the tail area.
Check your plastic tanks empty first to make sure you're not gonna melt them at the first engine start and during taxi.
This plane is an amazing flier: I've had an engine flameout in a low level roll, I managed to land on my feet. It is a true glider...
It performs all the conventional aerobatics in a beautiful old fashion way and is very impressive by it presence in flight.
lands like a pattern flier as well:
Check my article in the next RCJI issue for a complete build report and more.
#124
RE: PST F-84G Build Thread
Here is the 635 RS installed ( gear not fully slided in )
This requires a lot of adaptation work. All the plywood parts have to be machined including the outer rib ( check the picture ).
I have placed a big carbon roving along this rib to reinforce it.
The 635Rs itself is modified: shortened and reinforced.
The unit is very good: bigger piston, no leak, bigger arm, smooth operation.
The gear will retract and lock with 40 PSI of air.
From 100 PSI to 50 PSI ( Tam failsafe setting ) I have 5 full extend/retract cycles available with a very high power.
Beautiful.
Now I can start to concentrate on the finishing...
This requires a lot of adaptation work. All the plywood parts have to be machined including the outer rib ( check the picture ).
I have placed a big carbon roving along this rib to reinforce it.
The 635Rs itself is modified: shortened and reinforced.
The unit is very good: bigger piston, no leak, bigger arm, smooth operation.
The gear will retract and lock with 40 PSI of air.
From 100 PSI to 50 PSI ( Tam failsafe setting ) I have 5 full extend/retract cycles available with a very high power.
Beautiful.
Now I can start to concentrate on the finishing...
#125
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RE: PST F-84G Build Thread
I agree with you regarding the gear plates. They are seriously wrong. Per the advice of Molar mender (thanks Roy), I rebuilt the gear plates with ply and carbon fiber and lengthened them so that they extend beyond the wing ribs. I then sandwiched them with laminated 1/8" x 1/2" carbon fiber glued and screwed to the top part of each rib. We took the jet out this afternoon to try it out. They're so much stronger now. I also shimmed the aft part of the retract with 1/8" ply to rotate the strut forward so it's more perpendicular to the wing. Not only did this make it stronger, it really improved the take off by changing the moment of rotation of the nose. We put on 2 flights but we're still having trouble with the gear retracting. I'm using 120psi and 2 large tanks for volume. It's really frustrating. ( PST needs to get it together and provide some equipment that works! ) Hopefully they'll get the "new and improved" retracts out soon so we can finally enjoy all aspects of this jet. By the way, I agree that it (even with the gear down) flies and lands nice.
Here's a few pics:
Here's a few pics: