New Composite ARF SU27
#601
I am balancing my SU27 at 10mm in front of main spar for the maiden. Was planning to balance with gear down and fuel cells empty.
Wondering where others are ending up with final CG and overall recommendations for checking CG; dry or landing fuel as well as gear up or gear down.
Thanks
Roy
Wondering where others are ending up with final CG and overall recommendations for checking CG; dry or landing fuel as well as gear up or gear down.
Thanks
Roy
#602
Roy
From the ones we have flown here I would go back to the centre of the wing tube straight away on the SU-27. It’s very tolerant on the balance but my guess is that for some the balance could end up on the rear edge of the spar.
From the ones we have flown here I would go back to the centre of the wing tube straight away on the SU-27. It’s very tolerant on the balance but my guess is that for some the balance could end up on the rear edge of the spar.
#604
Join Date: Mar 2017
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[Quote = Maggoo811; 12532922] Deci , aici sunt unele mai multe fotografii de la construi meu și vopsea de locuri de muncă - pentru cei care sunt interesați
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[/ quote]
Hi, Maggoo811.
I sent you a private message.
Please, answer me.
Thanks.
autodidact trenul de aterizare electric cu picioare behotec și electroni robinet
câteva detalii:
[/ quote]
Hi, Maggoo811.
I sent you a private message.
Please, answer me.
Thanks.
#605
And I sent a PM to you DAN, pease take a look....
Thxs
Thxs
[Quote = Maggoo811; 12532922] Deci , aici sunt unele mai multe fotografii de la construi meu și vopsea de locuri de muncă - pentru cei care sunt interesați
autodidact trenul de aterizare electric cu picioare behotec și electroni robine
câteva detalii:
[/ quote]
Hi, Maggoo811.
I sent you a private message.
Please, answer me.
Thanks.
autodidact trenul de aterizare electric cu picioare behotec și electroni robine
câteva detalii:
[/ quote]
Hi, Maggoo811.
I sent you a private message.
Please, answer me.
Thanks.
#610
It’s Andrew Birds model. We would have to do a balance check since it started near the factory point, but then as Andy flew it weight was initially added to the tail, then once he was happy the weight was removed and the batteries shifted back. Most guys here don’t use balance rigs etc, they fly and adjust to feel. The SU tolerates a huge balance range with no nasty habits. Since Andy is on here maybe he can check the balance of his fuselage without wings and tail as that is manageable. All of ours have additional tanks, so that changes the balance through the flight too.
#611
The tailerons really seem heavy at the trailing edge. When turning the model off the tailerons immediately drop the trailing edge down. Has anyone added weight near the leading edge of the tailerons to improve this or is it really not needed?
#612
None of ours have been counter balanced as it adds weight to the rear which would need compensating at the nose, but also there has been no issues with flutter either.
#614
I would not be complacent about the possibility of flutter.
My Mig 29 flew perfectly well but had stab. Flutter on its last flight, which it survived.
My Mig stabs. now have some balance ahead of the pivot axis which is at about 25 % mac.
In addition I have changed the servos, one on each stab., to the highly impressive Futaba HPS a700 and eliminated all slop in the control rods. These are very powerful servos with a very “tight” gear train which should make the whole setup highly resistant to flutter, which can be so quickly destructive. .I was lucky not to lose the Mig.
My Mig 29 flew perfectly well but had stab. Flutter on its last flight, which it survived.
My Mig stabs. now have some balance ahead of the pivot axis which is at about 25 % mac.
In addition I have changed the servos, one on each stab., to the highly impressive Futaba HPS a700 and eliminated all slop in the control rods. These are very powerful servos with a very “tight” gear train which should make the whole setup highly resistant to flutter, which can be so quickly destructive. .I was lucky not to lose the Mig.
#616
I would not be complacent about the possibility of flutter.
My Mig 29 flew perfectly well but had stab. Flutter on its last flight, which it survived.
My Mig stabs. now have some balance ahead of the pivot axis which is at about 25 % mac.
In addition I have changed the servos, one on each stab., to the highly impressive Futaba HPS a700 and eliminated all slop in the control rods. These are very powerful servos with a very “tight” gear train which should make the whole setup highly resistant to flutter, which can be so quickly destructive. .I was lucky not to lose the Mig.
My Mig 29 flew perfectly well but had stab. Flutter on its last flight, which it survived.
My Mig stabs. now have some balance ahead of the pivot axis which is at about 25 % mac.
In addition I have changed the servos, one on each stab., to the highly impressive Futaba HPS a700 and eliminated all slop in the control rods. These are very powerful servos with a very “tight” gear train which should make the whole setup highly resistant to flutter, which can be so quickly destructive. .I was lucky not to lose the Mig.
Interesting, I though a wille ago of running just one servo on the stabs... any one else doing that?
#617
Why would you put all that load on a single tiny 25 tooth spline, when you can share the load. Same reason we went two servos on the 1:5.3 Hawk and the Mephisto.
#618
Coffee time so:
Empirical data and experience suggests you dont need two mighty servos on a Mig 29. The Su. MAY be different but :
My Mig on which the stab has forward pivot point ( with consequent effect on aerodynamic balance) first flew with two JR 8411 servos. ( 12kg/cm) Current draw by the stabs. measured by the Weatronics, was very modest suggesting low servo load.
When the JR 6311 servo, (36 kg/cm) with twice the power of the 8411 s arrived, I replaced the two 8411 halving the risk of failure and simplifying installation. Again, current drain low, measured in flight, not guessed.
On the flight which suffered flutter ( which can create massive stress) the servo on that stab. the 6311,. Suffered NO damage to splines or gears and is now back in use on another model. Resolution and smoothness was unaffected.
The only damage by the flutter was to the stab. round bolt holes became oval but there was sufficient control to land safely.
Now the Mig has been overhauled the brilliant Futaba 700 with 70 kg/cm has replaced the 631s, one on each stab.
The huge torque is not required to move the surface, but the superbly tight gearbox and high torque will be highly resistant to flutter.
The 6311 metal gears ( brass ?) suffered no damage despite the violent flutter, so the 700s with a stainless steel output will I guess, be more than adequate. After the flutter experience I have no concerns.
Anyway the refurbished Mig is serviceable and will be flown soon and again, currents caused by servo defection, will be measured by the Weatronic Gizmo, and analysed.
I pass on this experience for what, if anything, its worth !
Coffee finished !
Empirical data and experience suggests you dont need two mighty servos on a Mig 29. The Su. MAY be different but :
My Mig on which the stab has forward pivot point ( with consequent effect on aerodynamic balance) first flew with two JR 8411 servos. ( 12kg/cm) Current draw by the stabs. measured by the Weatronics, was very modest suggesting low servo load.
When the JR 6311 servo, (36 kg/cm) with twice the power of the 8411 s arrived, I replaced the two 8411 halving the risk of failure and simplifying installation. Again, current drain low, measured in flight, not guessed.
On the flight which suffered flutter ( which can create massive stress) the servo on that stab. the 6311,. Suffered NO damage to splines or gears and is now back in use on another model. Resolution and smoothness was unaffected.
The only damage by the flutter was to the stab. round bolt holes became oval but there was sufficient control to land safely.
Now the Mig has been overhauled the brilliant Futaba 700 with 70 kg/cm has replaced the 631s, one on each stab.
The huge torque is not required to move the surface, but the superbly tight gearbox and high torque will be highly resistant to flutter.
The 6311 metal gears ( brass ?) suffered no damage despite the violent flutter, so the 700s with a stainless steel output will I guess, be more than adequate. After the flutter experience I have no concerns.
Anyway the refurbished Mig is serviceable and will be flown soon and again, currents caused by servo defection, will be measured by the Weatronic Gizmo, and analysed.
I pass on this experience for what, if anything, its worth !
Coffee finished !
Last edited by David Gladwin; 09-02-2020 at 12:43 AM.
#620
Yes, single engine performance is OK with a slight Yaw. Nothing to fear....one of my friends even tried to take off on one having not taken his isolator start switch off hold on one engine, so one idling and one throttling 🙂
#621
Agreed, I've seen a very controlled single engine landing with one Cheetah (160) running, had plenty of power to continue level flight with power to spare and make a normal pattern to land.
#622
Hi all,
I'm looking at purchasing / building the carf Su-30, its a high end build plane but would you say its well worth the money in the end. would everyone agree its worth the money or there are other jets that i should look at in this size spec? I also see Sky master also have a smaller mig 29 and larger su-27 and 30. How do these jets compare to the Carf models?
Thanks for your time
I'm looking at purchasing / building the carf Su-30, its a high end build plane but would you say its well worth the money in the end. would everyone agree its worth the money or there are other jets that i should look at in this size spec? I also see Sky master also have a smaller mig 29 and larger su-27 and 30. How do these jets compare to the Carf models?
Thanks for your time
#624
Hi all,
I'm looking at purchasing / building the carf Su-30, its a high end build plane but would you say its well worth the money in the end. would everyone agree its worth the money or there are other jets that i should look at in this size spec? I also see Sky master also have a smaller mig 29 and larger su-27 and 30. How do these jets compare to the Carf models?
Thanks for your time
I'm looking at purchasing / building the carf Su-30, its a high end build plane but would you say its well worth the money in the end. would everyone agree its worth the money or there are other jets that i should look at in this size spec? I also see Sky master also have a smaller mig 29 and larger su-27 and 30. How do these jets compare to the Carf models?
Thanks for your time
sm’s SU27/30 looks impressive There are three of them in my club, but it’s just to big...
i’m a proud owner of the Carf SU27 since they came out, and if I had the chance I’ll buy another one, it’s worth every penny...
#625
So based on recommendations from across the pond I am balancing the SU27 to start with just even with the front of the main spar. I modified the intairco CG template with new holes even with the front of main spar. Suspended from the wire loops the model appears to be perfectly balanced. The gear are down and fuel tanks empty with some fuel in the UATs. The scale cockpit does add some weight to nose. I will require 30oz of lead in the tail to balance and that is with ECU and afterburner light batteries under the air brake.