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E-flite P-47 Thunderbolt Crash Today .. bad. Repair or parts?

#1
I've only been flying 2 years now and had my first major crash today. I learned on my apprentice and last Christmas I felt comfortable enough to buy the P47 razorback... I loved the plane. Last month right after landing one aileron starting wigging out back and forth and it seemed like a broken servo gear so I upgraded to metal gears. I replaced then last week and today was my first flight post repair. It didn't go well.

After a ground pre check and with SAFE on, I took off and began to bank left to come around for the first leg of my box. It continued to bank, rolled inverted and back dived straight into the ground with great speed. It disappeared behind trees but the impact was loud and I immediately wrote it off. I believe something malfunctioned with the new servos and they became stuck at full throw and kept it in the roll. Not sure but I felt like I had no control once it started to bank.

Upon recovery I was surprised to see that the fuselage suffered the most damage but the wings seem to be ok barring some nicks. I'm unsure of the motor condition but the propellor shattered so that might be toast.

The fuselage is only $57 to replace so if the rest seems ok visually should I repair it or is general consensus not to reuse receivers and electronics after a major crash?

If it's not repairable I had an idea to try and build one of the flite test kits. Can I put the SAFE RX into any plane or are they calibrated specifically for certain planes?

As I assess the damage this week I'll post more detailed pics but this was the result of my first major crash after 2 years. Back to the apprentice for a while.

Jim

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FDS

Well-known member
#2
That’s repairable, you could do the job with glue and cocktail sticks instead of a new fuselage. DeluxeMaterials Super Phatic and Zap Foam Safe CA will work on the parts without damaging the foam. Keep the glue layer as light as possible and only use a couple of cocktail sticks per joint or cut them in half for joining, to keep weight added to a minimum.
After that’s done I would get the metal gear servos out of there, they are way overkill for such a small, light aircraft and are going to be messing with your weight distribution a bit. Look to replace them with as near to stock weight ones as possible.
The next thing to look at will be potential damage to the aileron hinges, it sounds like your controls were off right from the start, which probably made it uncontrollable. You don’t want that happening again as it will spell the end of the glued airframe!
Get it back together on the bench, hook it all up with the prop OFF, test everything. Make sure all thecobtrol surfaces are smooth, not reversed and that the hinges of the ailerons are not sticking or damaged. Check the throttle control, Safe mode and that safe switches on and off, plus the rates switch works. Then un plug, refit the prop, then revisit CG. You might have to mess with it a little bit depending on how much weight the repair adds.
My Sport Cub S had the whole tail ripped off by my stupidity and half the nose, plus cracks in the root of both wings, it’s been repaired with Zap and thin tape, been flying fine like that for 6 weeks.
Sorry to see such a mighty warbird in need of a visit to the riggers and fitters. You need Bob!
 

Arcfyre

Well-known member
#3
Yikes, she took a hit, didnt she?

While repairable, It will take some skill and careful repair to get that plane airworthy again. As @FDS mentioned, the trick will be to keep the work as light as possible.

I will instead advocate for your other option. I have come to treat airframes as disposable, and electronics as valuable. In my opinion, even if you got that plane back together, it will probably never really fly the same way again. Not only that, but I would be leery doing high-G manuevers in an aircraft with a fuselage weakened in two places. That said I think you should salvage the electronics and build a new airframe for them to live in.

I don't know enough about putting SAFE into another airframe. I know its possible, but I have never done it so I can't really give you much advice.
 

FDS

Well-known member
#4
If the above was the choice then a $40 new main fuselage is better value, since the rest would be retained and the Safe functionality would be easier to keep.
 

jpot1

Well-known member
#5
Agree with @FDS above. I have repaired many planes with pieces of bbq skewer or toothpicks and CA or gorilla glue. One other tip, looks like some crushing of the foam in the nose area. Boil a pot of water and hold the foam in the boiling water. Many times the cells in the foam will reexpand and make the area look much better.
 
#6
Thanks guys. Yes the nose is crushed that was another reason I thought I wouldn't be able to get everything lined up correctly. For $57 I get a new fuselage with a new cockpit canopy too. I'm thinking that would be the better bet. I'm assessing it now. Here are some detailed pics.
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Arcfyre

Well-known member
#10
I guess it depends on how much you like that model. In my opinion that fuse is toast. For $57 you can buy a whole heap of foam board.
 
#11
More good news. All electronics seen to be ok. All flaps, gear, elevator, rudder and ailerons are working correctly... Which makes me wonder what happened during the crash.

@FDS said to get rid of the metal servos. They are just metal gear servos but they are the same 9 gram as the original. I got a lot of suggestions to upgrade to metal gears because the plastic teeth strip too easily. That's what happened to make me repair it on the beginning. Are there ok or no? Maybe switching to a different brand servo required additional settings? When I ground tested it everything seemed ok.... But again I'm still kinda new at all this.

After assessing the damage, I think for $57 I'm going to replace the fuselage and try to salvage everything else.... Just for practice, I'm gonna try and glue to fuselage first but if there is anything I don't like then I'll scrap it.

As far as damage, I'll need a new propellor, new engine cowl, and new fuselage.... The bombs and guns I can do without for now. All in all, a pretty cheap escape considering the crash.

I wish I had it on video or FPV LOL!

Thank you everyone for your comments and help.

Jim
 

FDS

Well-known member
#12
Wether the servos are the source of the aileron problem will depend on how carefully you test everything. That is not a heavy or large control surface. A metal gear servo will always weigh more than an equivalent plastic gear servo, a good compromise might be something with more torque in the same size package, without the weight gain.
The only way to tell what caused your crash will be to reassemble it all and examine every part in detail. I would suspect a mechanical fault in the aileron first, since that likely caused your aileron servo failure to begin with, but a methodical approach is always better than just throwing parts at random, since you can spend money without curing the fault, resulting in a repeat as soon as you fly again.
If everything is working properly then you can reappraise the CG and check it’s not radically off, remember a little nose heavy is better than any tail heavy.
 

AkimboGlueGuns

Biplane Guy
Mentor
#13
If you want a beater plane to fly then this is an opportunity. Beaters are great for learning maneuvers you wouldn't otherwise try since you care less about them. However, a new fuselage is still an option if you want to fly it into the ground and then move all the electronics into the new frame. That's honestly my recommendation. Fly the parts you have and then once you can't make any reasonable repairs swap all the parts into the new fuse.
 

Hai-Lee

Old and Bold RC PILOT
#14
Whichever route you go to get the plane back into the air I would seriously revise the Rx antenna installations. The "Feel" of having lost control should not be ignored. With spectrum here we try to get newbies to use Rxs with a satellite Rx which is located as far from everything metal as is possible.

Since doing so the number of crashes similar to that you experienced has dropped to less than 1 in 350 flights. Yeah we keep stats!

Just a thought!

have fun!
 
#15
Whichever route you go to get the plane back into the air I would seriously revise the Rx antenna installations. The "Feel" of having lost control should not be ignored. With spectrum here we try to get newbies to use Rxs with a satellite Rx which is located as far from everything metal as is possible.

Since doing so the number of crashes similar to that you experienced has dropped to less than 1 in 350 flights. Yeah we keep stats!

Just a thought!

have fun!

Can you explain this better please? Satellite RX? I thought Spektrum were great? No?

Jim
 
#16
As far as the servos are concerned... Do I need to stick with the stock servos to have SAFE work properly? I have stripped 3 servos and they seem to be a problem. It was recommended that I upgrade to metal gears which I did and then 30 seconds after takeoff my plane is in pieces. The reviews on horizon hobby for the 9 gram eflite servos are terrible and I've
experience this first hand... What options do I have? Leave the metal servos in or go back to the show eflite ones and risk stripping a gear mid flight?

I replaced them with 9 gram FMS digital servos. Was that a mistake? On the ground they seemed to be ok.

Jim
 

AkimboGlueGuns

Biplane Guy
Mentor
#17
Servos shouldn't be a problem, the SAFE system is all built into the receiver. Metal gear servos are definitely a good upgrade, far less likely to be stripped in a crash.
 

makattack

Winter is coming
Moderator
Mentor
#18
The only potential issue I see in your replacing the servos you had with digital servos is that they can draw more amperage vs standard analog servos. Perhaps that caused what's known as a "brownout" of the ESC/BEC? That might cause the receiver to lose power momentarily and then go into failsafe or some unknown state.

If you are sticking to digital servos, and you have a plane with so many servos already (flaps, gears, elevator, dual ailerons), that would be my guess as to the cause.

In any plane I have with digital servos, I use an independent BEC for those servos, and assume they can draw up to 2A in current for a 9g digital metal gear servo.

According to this: https://www.horizonhobby.com/pdf/EFL40ABrushlessESCInstSheet.pdf

The BEC on your ESC is rated to 2.5A continuous draw, and they state it's ok for up to 4 servos... but I'm assuming that's 4 analog servos.
 
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Hai-Lee

Old and Bold RC PILOT
#19
Can you explain this better please? Satellite RX? I thought Spektrum were great? No?

Jim
Spektrum Rxs are ok and their one great advantage is that they are used almost exclusively in BNF retail offerings but their antenna installations are basic to say the very least. Due to the short Rx antennas and that they need to be located almost amid the planes wiring the Rx signal can become blocked quite easily by the wiring and other metal structures within a plane.

A satellite Rx is another RX that you can plug into the first and locate further away from the metal signal blocking parts in the plane.

If spektrum did not think that signal blocking could be a problem with their Rxs they would never have made a satellite Rx in the first place.

I have and have used spektrum and quite a few other brands and my current Radio of preference is definitely not spectrum. I use radios systems with very long and easily located Rx antennas.

Just because you have Spektrum installed does not mean you will not experience a LoS. Actually Spektrum Rxs have a LoS counter feature:unsure::rolleyes:.

Revise your antenna installation or you could be facing the first of many rebuilds of your P47!

Have fun!
 

FDS

Well-known member
#20
If you use a better servo than the Eflite one, like an HT 45 or HT 65 with ball bearing shaft and karbonite gears you can have fast response and light weight with lower current draw.
I had not considered brown out, another reason to bench test all the components together.