Official Freewing Twin 80mm/90mm A-10 Thunderbolt II Thread

[TScott]

Did you set the elevators at the recommended 3 to 5 degrees reflex?

[TScott]

Did you set the elevators at the recommended 3 to 5 degrees reflex?

Started with the elevators set to the recommended up trim lining up with the small ”pimples” on the tail.

[TScott]

Started with the elevators set to the recommended up trim lining up with the small ”pimples” on the tail.

Like I stated, it’s got nice level flight once up to speed. But full throttle on takeoff or to go around pitches the nose forward.

[TScott]

Did you set the elevators at the recommended 3 to 5 degrees reflex?

Yes. I set the elevators per the manual and used the “pimples” on the tail as a guide. I have straight and level flight. It’s only when it breaks ground on takeoff or going full throttle on a aborted landing when slow.

[crxmanpat]

Where is your CG? If at the manual recommended 78mm, this is too nose heavy. It flies much better at 86-90mm.

[TScott]

Where is your CG? If at the manual recommended 78mm, this is too nose heavy. It flies much better at 86-90mm.

I’m going to check it again before my next flight. For now, I have a nose gear retract to replace.

[xviper]

That's odd. Something's "off" on your plane. Did the nacelles seat perfectly flush? Sounds almost like the front end of the nacelle assembly is raised a bit.

[themudduck]

I’m going to check it again before my next flight. For now, I have a nose gear retract to replace.

I agree, you're probably nose heavy. This model (and the nose gear) does much better with the CG moved back.

[TScott]

That's odd. Something's "off" on your plane. Did the nacelles seat perfectly flush? Sounds almost like the front end of the nacelle assembly is raised a bit.

After I checked out the retract and repaired a door, I checked the nacelle and verified it is flush on all sides.

[Bazza]

OK something is definitely wrong, I maidened my plane the other day and I set the Cof G at 90mm exactly and even had a friend double check to make sure I had it correct. The minute the plane left the ground I knew I was in trouble as the rear of the plane would not lift up when I tried to level out and when I attempted the first turn the plane flipped upside down. I was able to get it right way up but on the next turn it flipped and then nosedived into the ground. Upon checking the wreckage, thinking the batteries had moved on take off the front battery was destroyed which started a grass fire, but the rear battery was found to still be attached to the plywood and still held tightly in place by the battery strap. both myself and my friend have many many years flying experience and neither of us could work out what the problem was except that the cog was too far back, but it was set at 90mm like everyone on here is recommending

[GliderGuy]

Hi Bazza, Please provide more pre-crash data.

- ***Exact method of CG measurement***(wheels down, wheels up, finger method, upside down, right side up, or details of a more precise method)
- Battery brand and size for weight info
- Exact details of battery locations before flight
- Any mods done? If so…what?
- Flaps down or up
- Control set-up…any mixing of flap-elevator
- Were you on high rate or low rate?
- Position of neutral elevator setting was what?
- What is your EDF and large EDF flight experience?
- Did you perform a range check and verify correctness of movement?
- Radio gear brand/model and location/any satellites?
- etc….

Sorry for your loss, but more data is needed because otherwise all the analysis can be is, “ Yep…you crashed.”

It does “seem” like a tail heavy condition, but don’t rule out radio or control set-up issues or pilot over controlling (to be blunt-pilots do cause crashes…not fun to state and not meant to be a slap in the face…but pilot experience can’t be ruled out with the info provided so far). I flew the A-10 as my first EDF after flying smaller/slower prop trainers and after having some stick time on the FL P-38. I will admit that the maiden wasn't pretty, and I busted the nose gear by getting into the dreaded crow hop on landing. Just saying.....gotta look at all possibilities since you asked.

-GG

[Hugh Wiedman]

OK something is definitely wrong, I maidened my plane the other day and I set the Cof G at 90mm exactly and even had a friend double check to make sure I had it correct. The minute the plane left the ground I knew I was in trouble as the rear of the plane would not lift up when I tried to level out and when I attempted the first turn the plane flipped upside down. I was able to get it right way up but on the next turn it flipped and then nosedived into the ground. Upon checking the wreckage, thinking the batteries had moved on take off the front battery was destroyed which started a grass fire, but the rear battery was found to still be attached to the plywood and still held tightly in place by the battery strap. both myself and my friend have many many years flying experience and neither of us could work out what the problem was except that the cog was too far back, but it was set at 90mm like everyone on here is recommending

Sorry to hear that, as this A-10 when it's right, is the smoothest flying EDF I've ever seen and probably the easiest plane to fly in my fleet. I concur with GliderGuy that we'll need some more info and even then may be difficult to diagnose the problem. Does sound like you were tail heavy, but I can absolutely guarantee you that if you were at 90mm, that 's this aircrafts sweet spot IMO. I actually fly mine at more like 95mm. I always balance it inverted with gear down using the unfortunately discontinued Great Planes CG Balancing tool, which has never let me down.

I do have one thought, and there may be some other control surface issues that are probably impossible to determine now (like maybe even a gyro correcting in the wrong direction??). I'm wondering if your elevator neutral position was set with too much up elevator. Keep in mind that this is one of the few EDF's that the twin exhaust thrust goes DIRECTLY over the elevators and those elevator stabs are only 8" behind the end of the exhaust nozzles. You will notice in static testing and when holding it that when you have anything over 50% throttle and input up elevator, the thrust pushes hard down on those elevators and you can even hear a major difference in the sound of the air going over the surfaces. So any up elevator will be magnified by increased throttle input. Down elevator, on the other hand, only is affected by air speed. I've notice with this bird that at full throttle, the elevators are extremely responsive to up elevator input for that reason, and less responsive (actually more like most aircraft) to down elevator input.

Long explanation made short, if you have too much up elevator trim for neutral, you will probably get exaggerated down force on the horizontal stab. Especially on take-off and climbing when you are most likely at/near full throttle, the additional up elevator you give for take-off will be exaggerated and relaxing to neutral if it's still too far up will exacerbate the condition. As you're going into a turn, you're not likely to use down elevator (usually you're using a little up to stay at the same altitude) and that too much trim along with the typical slight up elevator input may continue to push the tail down and most likely cause the plane to over rotate (and that's assuming each elevator is centered the same-any difference would add to the problem).

Anyway, I'm probably way out in left field on this one, but just a thought. Hope you get it worked out as it's a shame you were not able to experience the joy of flying this aircraft and unfortunately probably are left with a real bad taste in your mouth for it. Can't blame you for that, but if you can, get her fixed up and get back in the saddle!

[themudduck]

Hey Bazza, sorry to hear of this incident. Something was definitely wrong, I can't imagine how tail-heavy it must have been to behave like that. Where did you measure 90mm from?
Should be about 3.5 inches back from the LE of the wing where it meets the fuselage.

We need more info - I would like to know where you put your batteries. Did they look like this picture?
Or did you have them both in the back tray?

[Hugh Wiedman]

Hey Bazza, sorry to hear of this incident. Something was definitely wrong, I can't imagine how tail-heavy it must have been to behave like that. Where did you measure 90mm from?
Should be about 3.5 inches back from the LE of the wing where it meets the fuselage.

We need more info - I would like to know where you put your batteries. Did they look like this picture?
Or did you have them both in the back tray?

Damn Marc, that looks way more nose heavy compared to mine. I must be a good 120 mm further aft on the battery placement than you are. In fact I had to remove the circuit board screwed in to back end of the battery tray and stick it on the port fuselage wall just to get the batteries all the way back in. This photo has the RT 6250's each weighing 795 gr although now I'm exclusively using the SMC 6200's each weighing 814 gr pushed back even more and it definitely is not tail heavy for me. I do have the 3D printed "Dirty Dee" cockpit and a 1/10 scale JHH full body pilot in the cockpit adding a bit more weight to the nose, but I'm still around 92-95 mm on my balance point. Flies smooth as silk for me, with the gyro on or off. That front battery only has 1/8 of it on the elevated front battery tray so I had to add a platform holding the remaining 7/8's level where it steps down so it could lie flat.

[themudduck]

Damn Marc, that looks way more nose heavy compared to mine. I must be a good 120 mm further aft on the battery placement than you are....

Yes I know, that pic I posted was the initial setup I had two years ago, per the manual, before we learned. Now I have my batteries sitting very similar to the way yours looks. But from Bazza's description of what happened it made me wonder if he had anything in the front compartment.... because it sounded like his plane was extremely nose heavy. I'm curious where he placed his batteries.

[Capt_RedBeard (NOR)]

Hi guys! New A-10 RC pilot here. Does anybody know the estimated stallspeed (indicated) of this gorgeous plane? Setting it up with a pitot-tube to be able to ride the stall limit for slow and low loveliness. Yes, I am aware of the possibility of finding it out for myself, but right now I am pre-maiden, and would love to have some reference number to start of with.

[crxmanpat]

Welcome and congrats on the A-10! It's one of my 2 favorites (next to the F-22). This plane has practically no stall at all and will fly very very slow, especially with full flaps out. It is probably the most stable airframe Freewing has ever done.

[xviper]

Hi guys! New A-10 RC pilot here. Does anybody know the estimated stallspeed (indicated) of this gorgeous plane? Setting it up with a pitot-tube to be able to ride the stall limit for slow and low loveliness. Yes, I am aware of the possibility of finding it out for myself, but right now I am pre-maiden, and would love to have some reference number to start of with.

Each plane flown at each location will have a different stall speed and different stall characteristics. If you have a pitot tube speed device, you would be best to take it up high and find out for yourself what your plane will do. Until you do this keep the speed up. Go up high and begin slowing it down until it can't fly anymore. You should have plenty of altitude to recover. Sometimes, the best way is to find out for yourself, in a safe, controlled way. I do this for every new plane I get. Not going to rely upon some number someone else throws out.

[Capt_RedBeard (NOR)]

I have flown some fullsize, and understand basic airmanship. I totally agree with figuring it out myself, but still looking for a referancenumber to start of with. I’m guessing most RC pilots normally don’t know the stallspeed of their plane, but I am a bit anal about these things 😁

[xviper]

I very much doubt many have pitot tube speed sensor telemetry. I have one without telemetry but even that is a nuisance to mount on different planes every time I'm curious about speed.