RE: OV-10 Bronco 81"  
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RE: OV-10 Bronco 81" - 5/15/2007 7:44:37 PM   
Yakflyer



Posts: 129
Joined: 3/7/2005
From: Barnesville, GA, USA
Status: offline 		On my way home, was reviewing the accident over and over in my mind like you would on a DVD using pause and slow motion. It still did not make any sense to me what had happened. Even with an engine out, that bird flys so well you do not know it is out unless you see the prop hung stationary.
Okay, now I am at home, cut and bleeding from the ground side of the SAR feeling pretty down.
This is what i checked;
Both props only had one blade broke. From what I have learned that could be a good indication that the plane responded to my idle down/kill command.
One engine is just fine (right hand side). Cleaned her up, check the valves, crank shaft, rocker arms, cam and tappets. All looked in good order. Put her on the test stand and fired her up with one flip. She ran as good as the day I got her.
The other engine suffered external damage only. The back plate broke where the carburator bolts on, the high speed needle assembly was bent at a 90 degree angel and a slight dent in one of the push rod tubes. Less than $100 to repair. Compression was fine. Parts came in and she runs great.

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Fly'em high, land'em softly!
Yakflyer

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       Post #: 426

RE: OV-10 Bronco 81" - 5/15/2007 9:02:10 PM   
Yakflyer



Posts: 129
Joined: 3/7/2005
From: Barnesville, GA, USA
Status: offline 		Rx tested fine. Various range tests were conducted and no problems found. (Rx is non PCM, it is a new standard 9ch Dual Conversation Futaba)
All 11 servos were in good order too. No gear damage. Whew!

On board glow ignitor system was fine too. Just had to replace a couple of wires that were skinned in the crash.
All controll surfaces were still attached and accounted for (minus crash damages

On my next trip to the airfield, I spoke with a few other pilots that flew earlier that day and two mentioned they had what appeared to be temproray loss of controll for about 3-5 seconds too. Niether of them suffered a crash. Thankfully.

My self proclaimed NTSC of the RC Field (comprised mostly of Senior pilots) believe there was some radio interferance. What, how, where from, we do not know, but that appears to be the only possible explaination that would make sense.

Will I build another OV-10? You bet! That bird is too sweet to fly not to! I will have to save my allowances, be good to my wife again and hope Santa will ready my letter this year.

I would like to thank all who offered their input and advise while building the model. I really appreciate all the good advice.

Yakflyer

Fly 'em high, Land 'em softly

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Fly'em high, land'em softly!
Yakflyer

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RE: OV-10 Bronco 81" - 5/16/2007 12:32:03 AM   
FliteMetal



Posts: 1326
Joined: 10/9/2002
From: Houston, TX, USA
Status: offline 		Like mobile home parks and tornados....saplings and planes.


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http://www.FliteMetal.com

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RE: OV-10 Bronco 81" - 5/16/2007 12:38:20 AM   
fancman


 

Posts: 1286
Joined: 11/21/2002
From: N. Charleston, SC, USA
Status: offline
AWWWW Man Sorry for your loss. What a bummer

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RE: OV-10 Bronco 81" - 5/19/2007 6:51:24 AM   
gator8287


 

Posts: 32
Joined: 3/21/2007
From: Nanoose BAy, BC, CANADA
Status: offline 		Does anyone know what covering was used on the hobby hanger 81" arf

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Don (The Gator)

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RE: OV-10 Bronco 81" - 5/20/2007 6:29:23 AM   
Telemaster 56



Posts: 28
Joined: 12/5/2004
From: Goose Bay, NF, CANADA
Status: offline 		I'm at the point in my Bronco build where I'm building the nacelles. In the construction article in the February 2001 issue of Model Airplane News Rich Uravitch says "The only bulkhead that should not be square is the right-hand nacelle firewall. It should be installed to provide 3 degrees of right thrust to help with those rare engine outs."
I'm wondering if others who have built the Bronco did this or not? I can't understand how it would help, and why only the right nacelle firewall? Either engine could fail of course. Many thanks!

Gord

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       Post #: 431

RE: OV-10 Bronco 81" - 5/20/2007 3:30:42 PM   
CanDo


 

Posts: 82
Joined: 2/23/2006
From: Ventura, CA, USA
Status: offline 		I set up my smaller Uravitch Bronco with 3 degrees offset for the right nacelle. When I flew it, I throttled back the left engine to idle and found the plane was very manageable with just the right motor pulling. I don't think you will regret putting the offset in if you experience a left engine out.
-Les-

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       Post #: 432

RE: OV-10 Bronco 81" - 5/20/2007 4:36:11 PM   
FliteMetal



Posts: 1326
Joined: 10/9/2002
From: Houston, TX, USA
Status: offline 		There is no reason to build in any offset in an OV-10 of any size as the props are
so close to the centerline of the "H" tail that the plane will track true whether you
make a left or right turn with an engine out. I believe Rich even stated this either
on the planset or instruction sheet.

The 1:1 has next to no effect by an engine out either. One of selling points of the
D+ rev. is an illustration showing take off to altitude to complete a mission with a
single engine.

Note that's over 14,000 pounds at takeoff...



< Message edited by FliteMetal -- 5/20/2007 4:39:49 PM >


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RE: OV-10 Bronco 81" - 5/21/2007 3:23:35 AM   
CanDo


 

Posts: 82
Joined: 2/23/2006
From: Ventura, CA, USA
Status: offline 		-Great information! Since I'm also starting to build my nacelles, I went back to the construction articles for the 52" and 81" Uravitch Bronco. Essentially the larger Bronco is ~50% bigger than the 52" plane, but very similar in overall design. Both articles indicate you should add 3 degrees right offset to the right engine for left engine out situations.
-Then I went to my Bronco Squadron/Signal publications and I may have an answer. I don't know if later variations changed, but the OV-10A Broncos had 715 p Garrett Turboprop engines; "To eliminate torque, each engine turned in opposite directions". Since 3 degrees offset shouldn't hurt performance, I think I will add it for good luck!

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       Post #: 434

RE: OV-10 Bronco 81" - 5/21/2007 4:18:04 AM   
fancman


 

Posts: 1286
Joined: 11/21/2002
From: N. Charleston, SC, USA
Status: offline

Question 163 "twinman what would happen if the engines were facing angles outwards. my thery is that if one goes deadstick it will fly in a reasonably straight line."

Twinman: "Hi, There are many opinions on the subject of outward thrust settings. One is that due to engine torque, the left engine should be angled out and not the right. The Profile P-38 angles both out, for just such reasons as you are proposing. The final truth, to me, is that, no practical engine angling out will prevent the plane from yawing and trying to spin without that addition of rudder control. Learn to fly coordinated rudder at all times. Personally, my engines are placed so that the engines face straight ahead on all my planes.
Good Luck and get to flying. Twinman"

http://www.rcwarbirds.com/Advisors/Twinman/advisortwinman.htm

http://www.rcwarbirds.com/Techniques/techniguespage.htm#t2





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       Post #: 435

RE: OV-10 Bronco 81" - 5/21/2007 4:27:59 AM   
Telemaster 56



Posts: 28
Joined: 12/5/2004
From: Goose Bay, NF, CANADA
Status: offline 		Ahh so you're saying that because our engines both turn in the same anti-clockwise direction that is why only the RIGHT firewall has the 3 degree right off-set?? Maybe that would explain why the LEFT firewall has no off-set. Sinch Rich has said to build in the off-set in both big and small Bronco models I'm sure he has a good reason for saying so. If you read this Rich let us know your thinking on this firewall off-set matter.

Gord


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       Post #: 436

RE: OV-10 Bronco 81" - 5/21/2007 4:36:40 AM   
Telemaster 56



Posts: 28
Joined: 12/5/2004
From: Goose Bay, NF, CANADA
Status: offline 		Sorry to hear of the loss of your Bronco... I apprecated your detailed report on the accident though. Great job there, thanks!

Gord

(in reply to Yakflyer)
       Post #: 437

RE: OV-10 Bronco 81" - 5/21/2007 4:43:45 AM   
Telemaster 56



Posts: 28
Joined: 12/5/2004
From: Goose Bay, NF, CANADA
Status: offline 		Well, I wasn't aware of the air bleed low end system on LA engines. Thanks! Guess I'll have to go with .61 FX's. Third engine change decision during the build so far. Oh well, I'm only on the nacelles right now, time to save up for the more expensive engines.

Gord

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       Post #: 438

RE: OV-10 Bronco 81" - 5/21/2007 6:06:34 AM   
Wayne22



Posts: 4433
Joined: 4/10/2002
From: Edmonton, AB, CANADA
Status: offline 		Any plane will yaw to the left due to mysterious and highly debatable forces such as torque, spiral slipstream, and P factor....that is a given - we know it happens........

On a twin engine plane the same is true., Now if the right engine quits, the left engine will induce an imediate yaw to the right (towards the dead engine) while the mysterious forces are still inducing a yaw to the left....at certain power levels and airspeeds, these yawing forces may cancel each other out, hence many designers don't add outward thrust to the left hand engine....

If the left engine fails, the right engine induces an immediate yaw to the left, aided this time by the mysterious forces also inducing a yaw to the left...so they are additive in this case. Some designers choose to build in offset thrust to the right to counteract the engine-out induced yaw. Again, subject to power levels and airspeeds, this may help an engine out situation.

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All I ask is for a chance to prove that money can't make me happy......

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