MormonMike

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OK, I understand. But I always have a heck of a time getting fiberglass to lay down flat. some small "bunching" up, some curling or strands not laying down. Its difficult to work with for me. The polyurethane coats wont fill in the pores of the balsa i take it, and I've yet to find a coating that will fill in the pores of the wood to a sandable smooth finish. Since I doubt my ability to have a perfect finish with that stuff, it looks like Im going to have to swing back towards Ultracote. You would think that there should be something on the market that when applied with a brush would fill the pores and give a smooth hard finish. And yes,I know, it adds weight with each coat. There has to be a "gel" coat of somekind. I'll check on this and get back with you. Seeya, Michael

rryman

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Well, I finally laid the paint to it tonight. Came out a little darker than I wanted but it was the only color I could find close enough in Lustrecote. Added a coat of flat clear to it to dull it down. Anyway, now on to assembly and finishing the thing. Never built a plane that I had so many pieces to work with!
Cal, how did the balance come out for you. Was it tail heavy? I was thinking mine would be, but now I'm not so sure. the fuse pod is taking on a bit of weight now.
Randy

MormonMike

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Randy, Looks pretty good. Lustercote huh, I've been looking into an automotive finish, something like a colored epoxy, hard as nails too, but hav'nt decided yet. Where are you getting your " low visability " markings from? Sorry to "bud" in like I've been doing on your thread but I really need to know all I can about this kit as I start on it. Michael

n3cal

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Looks really great Randy! Mine came out tail heavy. I've got a 1800 MAH flat battery pack mounted all the way forward in the nose to balance out per the plans.. My LHS didn't have a replacement fuel tank in stock so I've got one on order from tower. Should be in today I hope. Can't wait to get the maiden in!

My plans didn't show anything on the "pods/racks"?? Did you just add them yourself? I've noticed several pics on the net with them too?? They look good....

Cal

rryman

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Michael, the decals on the side are what I have left over from some Kyosho sheets I have had for several years. Tower was the only one that handled them, and now they don't anymore. Shame too, they were great for military stuff. I've checked everywhere and can't seem to find them. I guess when they're gone, they're gone.
I'm not that crazy about Lustrecoat, but that was about the closest color I could find so I went with it. I used Plasticote from Advance for the black on my Herk, and it seems to be working fairly well.
Cal,I built the sponsons myself. I have several friends on a veterans group I'm on who either flew or worked on the Bronco. One sent me some great pics of one he worked on while at NKP, Thailand. As far as I can determine, all OV-10's had the sponsons, but some had the guns removed from them. The finish in mine is going to be as close to #67-14626 as I can. That aircraft is now on display at Hurlburt Field, Fl. It sure got around. I'll put a pic on here of it in case anyone wants to use it for reference..
Randy

rryman

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OK, a few little tid bits for those of you who are starting/considering building this bird. I have started final assembly tonight on the plane. Things to plan ahead on:
1. If you are installing retracts, I can't see any way that mechanical retracts could be installed due to the confined space in the booms.
2. I have used Robart retracts, simply because that's what I had left over from my ground penetration test I did with my King Kobra last summer. (that's another story!) I had no problems installing them, but whatever air system you install, you will need extra "tees" and quick couplers for the gear to connect the air lines. A set of quick couplers will be needed in each boom and a set in the fuselage pod, where I put the air tank and retract valve. This is assuming that you build it so the fuselage pod can be removed from the wing as well as the booms. I personally can't see any other way to do it. There's plenty of room in the fuselage for stuff, but the booms are really cramped for space. Or maybe I'm just used to working with larger planes. (Maybe should have gotten the 90" version!)
3. As far as the plastic nose cone, I screwed it to the fuselage so it could be removed to add nose weight. In retrospect, I probably would have glued this on and blended it into the front of the fuselage, since I also installed a bottom hatch in the front of the fuselage, where I could/can add nose weight if necessary.
4. I ordered the cockpit kit and mounted all of it on a 3/32 sheet of balsa, which I screwed to the fuselage, and also screwed the canopy to the fuselage, so all of it can be removed. Had to do this, because the retract valve is mounted under the rear pilot in the fuse. I've just got this thing about model airplanes with no pilot in the cockpit. If you're not going to put the cockpit kit in, just paint the canopy silver and be done with it. But, you will probably need the nose weight anyway.
5. For weight and space savings, I have used some smaller Hitech servos, but will be running a 6 volt pack for a little more torque. As small as the control surfaces are, I believe this will work. I didn't compromise, however, on the elevator. Used a standard servo for that.

This is not a particularly hard build, but I'ts definitely not a beginners project. I'm still impressed that it was Cals second kit! By Sunday night, I should be able to predict some final weights, which I am not too concerned about since I added an additional 11" to the wing. OK, so I cheat! But I'll do that for better flying qualities. But, on the other hand, 11'' of extra wing to drag around the sky might just put a little extra burden on the engines. With 1000' of smooth grass runway, I think I can come up with suitable flying speed. I guess I tend to build in a little extra toughness in the landing gear areas, and places that might just take a little abuse when I make less than a perfect landing.
Hope this helps, if anyone woud like pictures of anything, let me know.
Randy

MormonMike

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Randy, an HS-225 MG/BB servo would be a better choice for elevator, 67 inches of torque in a servo about half the size of a standard. Yup, without proper markings the low-vise paint scheme just wont work. Thanks for the info about the markings though. I do remember the paint schemes for a few Broncs that were used quietly from about thirty years ago with the US Govt.Please post a few photos of it after its maiden flight. Would like to here about its performance. Thanks for all your info, Respectfully, Michael

rryman

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I used a 3004 on the elevator, the LHS was out of the 225MG's which is what I really wanted to use. But, I managed to get the three of them in the right boom, had to stagger them vertically for the servo arms to clear each other. I am going to be running a 6 volt pack for a little added torque.
Another suggestion for those building one. Do yourself a favor and enlarge at least one of the rib holes from the center of the wing out to each boom. I did, and after putting in all the plumbing, was glad I did. I fished in all the wires rather than put in paper tubes, since the distance was so close. I managed to get the rudders and throttles hooked up with one Hobbico long "Y" connector, which was long enough for each lead to reach from the center of the wing to each boom. Problem is, I'll have to use another "Y" to connect the nose wheel steering. One of the short ones will do for that.
I may get the whole thing assembled tonight and start testing. Need to find out where to put the battery, or how much more weight I need in the nose.
Randy

rryman

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Got the bird put together tonight and balanced. Even with a 1600mah 6volt NiMh pack in the front end, I still needed to add 4oz of lead under the nose cone. Glad now I didn't permanently attach it. Weight came out at 9.25#, which should put it in the 30-31oz. wing loading range. Also glad I added more wing to it! I did check it with the gear down and gear up, and it most definitely becomes tail heavy when the gear goes up, and that's the way I balanced it. Will probably be somewhat nose heavy for take off and landing, but should be manageable.

rryman

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OK, Bronco fans, here's the (almost) finished product. Still have some decoraation to add on some areas yet. This has been quite the exercise in building, having radio equipment in the fuselage pod, wing, and two tail booms. quite the mess of wiring to hook it all up. Now on to some engine tests.
Randy

Baldeagle

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Randy the Bronco is looking great. They are a nice flying bird too.

MormonMike

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Randy, what did you cover the wing with [ to match the paint elsewheres on the rest of the plane]? Michael. PS, Thats a sharp looking OV. Give us a profile shot from the other side showing engines please.

rryman

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The entire plane, wing and everything else is painted with Lustrecote Dove Gray. The wing was covered entirely with clear Worldtex, priimed and painted. I think it turned out nice for fabric over open ribs. The ribs don't show all that much.
Here's the shot of the engine side, and a pic of the art work I did on the tail tonight. This one is modeled after the one on display in the airpark at Hurlburt Field, Fla. Tail# 67-14626. Flew with just about every FAC outfit in SEA during its active life.
I am right proud of the way the "TAC" emblem turned out on the tail. Hard to get those things at all, let alone in the size you want. I kind of Rube Goldberg'ed this one on my computer.
Randy

rryman

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Finally got to an engine start this evening on this bird. I'm using MDS .28's with 9 x 6 three blade Zingalis. The plane moves pretty well with the props. I don't understand why this OV-10 at 9.25# moves good and the Transall at 7#wouldn't even taxi with the same props on OS .25 LA engines. Maybe it was the belly dragging on the Transall that made the difference. Or, maybe there is more difference between the .25LA and MDS .28's than I think.
Anyway, I'm still not satisfied with the engine performance yet. The 3 blades seem to be lugging the engines somewhat-not getting but about 9500-10k out of them. I am going to try 9 x 6 two blades tomorrow and see if that helps some. I'm getting in the 15k range with 9 x 6 two blades on the OS .25FX engines on the C-130. Just couldn't get the MDS engines to come together for some reason.
How's everyone else getting along on theirs?
Randy

n3cal

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Back to the original question of this thread: What size props for my Saito 40's. ?????

We had a perfect sunny afternoon here in Maryland and I had some time to get out to the field. I got a chance to taxi test the Bronco. It didn't go very well. Our 500' grass strip was pretty thick even after a fresh cut the same day. My current setup is 2 1/2" wheels all around, Saito 40 four strokes with 10 X 6 3 bladed props turning about 9000 rpm's max. It wasn't fast enough to break free of the grass. Too slow. :-( Not sure what size prop to try next? Maybee bigger wheels? Any advise guys?

Cal

rryman

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I can't be of much help with the prop selection, Cal. But, since you have fixed gear, increasing wheel size always improves grass field handling.
I currently have 9 x 5 two blades on mine. I tried 9 x 5 three blades but for initial test flights, I want a little more power than the 3 blades put out. I may try them later if everything works out.
I went to the field last evening with every intention of getting in a first flight on the bird, but elevator problems caused me to postpone the event. also, my son forgot to bring his camcorder and I was a little uneasy about that since we usually tape all test flights. Apparently I used an acid type flux when I soldered the threaded adapter to the cable , and it caused the cable to rust just inside the plastic tube it runs in. It got stuck, and also I noticed that the elevator horn was cracked where the clevice went in. Have no idea how that happened, but thought it better to check the stuff out, so we scrubbed the flight. I am ready again for another tes when we get to it.
Someone on another OV-10 thread is using Graupner three blade props. Someone else told me that they are good props to use. I don't recall seeing who sells them. I may get a couple of them to try to see if they are much better. I would like to use the 3 blades on this one, and also on the Transall and C-130 if I can find some that put out decent power.
good luck on the test flight and keep us posted.
Randy

n3cal

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Flew maiden flight this morning and another three flights after maiden! I changed out the three bladed 10X6 props for two bladed 10.5X6 APC's today! That did the trick! Got another 1000 RPM out of them and was able to escape the grass strip! Takeoff was long and exciting and after climb out a few clicks of up elevator and also a few clicks of right aileron trim and the Bronco was flying straight and true! It's a very nice flying bird! I'm very happy with first flights. Tried a couple of rolls and loops with no problems. Stall turns went very well and seems to have plenty of rudder. The bird lands very smooth too. All an all it's a winner! Can't wait to try off a solid runway later this year. The saito 40's are plenty of power.....

Cal

rryman

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Well, I tried a maiden flight today, but turned out to be a "maiden taxi run." Those MDS .28's just don't have what it takes to get the bird in the air. Tried several times, changed props to 9 x 5's, and it couldn't muster up the speed to break ground. I had to plead with those MDS engines to even break 12,000rpm with 9x5's. They just aren't getting it. I feel sure that OS .25FX would do it, and the .32's for sure. Guess theres another day in store for this one. The OS .25's on my C-130 have no trouble turning 15,000 with 9 x 5's. I' m sure an extra 3k would be enough. Small wheels don't help either, but the grass is short. On the bright side, it ground handles really well!!
Randy

n3cal

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Randy,

My most success was getting the nose up higher... Keep tryin! I spent three weeks with just taxi's untill today! I was pretty bummed.... I'm sure this plane flies fine off paved runway....


Here's a couple pics from today!

Cal

rryman

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Well, I'm going to give it another try tomorrow with the MDS engines and some changes in attitude of the plane. I installed a larger nose gear wheel, and lowered the axle to raise the nose higher and get the wing to more of a level attitude rather than sitting with negative incidence. I think it just might have kept it pinned to the ground. Another good observation that Pete (jmupilot) made was that the elevator sits up pretty much out of the air stream of the props so it will be less effective in getting the plane to rotate. My plane is pretty nose heavy what with the retractable gear, and will probably be even more difficult to get to rotate. With the gear up, it balances just right, but with the gear down it is pretty nose heavy. I also found a klunk line leak in the right engine that was causing problems and fixed that. Anyway, I'm going to give it another whirl tomorrow weather permitting. We've been having the monsoons here the last two weeks.
Randy

Baldeagle

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Randy on my 80in Bronco I had the same problem , raised the nose up to get it level sitting on the ground and it took off great.

TNRabbit

Hi Cal!

Saw your bird fly the other day and it looked GREAT![8D] Glad you got the problems worked out.

G~

rryman

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Tried again today, no joy. Those MDS engines just aren't cutting it. I have two engines that just don't perform. Why I can't get more than 12k out of them is beyond me. We previously used them on combat planes briefly and they were over powered on them, but using them together on a twin I can't get consistent running. I'm not going to sacrifice an airplane for crappy engines. I'll sit tight till I get some OS engines for it. I'm sure that another 3k will make a real difference. Besides, it isn't like I don't have any other twins to fly-C-160 Transall, AC-47 and 4 engine Herk. I can wait.
Randy

Matt Kirsch

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Hey, cool thread and aptly timed. I just maidened my OV-10 yesterday. 7lb, 6.5oz with 8oz(!) of lead in the nose to balance. Twin Magnum .25XLs with 8x6 Master Paintstick 3-bladers turning about 13000.

Even in the deep green Velcro these guys like to call grass, I had no problems with acceleration. My problem, and I believe yours, is with the angle of attack of the plane as it makes its takeoff run. Took me three tries, and when it finally came off, I nearly soiled myself. I had given up and pulled the throttles back when the plane suddenly popped up off the ground. Luckily it was going like a bat out of h#ll and had plenty of airspeed.

When you finally get it up, you'll like it. It's a little hotrod, goes like stink on a skunk. Even if the engines aren't perfectly synced through the throttle range, it flies straight and true. But boy, when the engines get about 500 RPM apart do they make a nasty racket! Sounds like the plane is coming apart, but it's only the "beats" as the frequencies get a couple dozen Hz apart.

rryman

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After my second attempt at flight, I'm convinced that I need more power. I have the wing sitting level now, and a larger nose wheel, but I just can't get enough ground speed to take off. I'll bide my time till I can get some OS .25 FX engines. Plus, I'm dealing with a few pounds more weight than you are. I do believe once it gets into the air and I get the gear up, it will be fine. It's just that I have retracts, and balanced it with the gear up, and with the gear down it is REALLY nose heavy. I don't want a repeat of a giant scale Corsair I read about years ago. the guy balanced it with the gear down, and on the maiden flight, when he put the gear up, it moved the CG back about 5 inches, and it promptly got tail heavy and re-kitted itself.
Randy