MJD

My Feedback: (1)

But It's more than that. To work with the existing cowl the firewall to prop drive face distance is about 3-1/2". This results in the exhaust completely intersecting/interfering with the nose gear mount area. In addition, I would have to Dremel out a tunnel in the firewall and and into the fuse to clear the exhaust, then line it with ply etc. Not tough to do, but again not in the spirit of the conversion. The nose moment is a bit much as it is, any scheme that involves lengthening it further by moving the engine ahead to clear is aggravating the situation and asking for too much lead in the tail.

I could make it a tail dragger but that is more modification than I want to make - not due to laziness (though I admit that can be a factor for me..), but I did not want to stray too far away from stock. I thought this would be an interesting idea for others looking for something new or different as a small sport aerobatic model (with a nostalgic look), but if it takes a laundry list of changes it kind of defeats the purpose. I have a sum total of about two hours at the bench invested in it to make the changes shown so far.

A side exhaust engine, inverted, will put the muffler through the cowl and clear of the fuse, and leave enough room for the nose gear mount, control horn and linkage.

I'll just have to come up with a better use for the Conquest. Winter is coming. A minimalist fuselage sport speedster kind of thing, 250-275 sq in etc. Maybe a Quickie 250, 7"x35" wing, along those lines.

klord125

I plan on using the Magnum .15 .. So I'm very interested to see how that combo works. I'm told the Magnum .15 is one little stout engine. Not to be confused with the Conquest in a league of its own.

Mr Cox

The Magnum is not bad for the money that it costs, but a Norvel .15 is both stronger and lighter.
Here how I've done the Zlin with a Norvel engine, I guess the cowl is longer compared to the contender;

MJD

My Feedback: (1)

I've seen some pretty impressive numbers for the Magnum, and it is available online so it seems like a good choice. It will be more than enough for this little aircraft, I'm sure.

MJD

My Feedback: (1)

Hooray.. just back from business travel, and waiting in my mailbox was a new toy - the Magnum XLS.15. The exterior fit and finish looks nice, lots of pinch (way more than my OS .15 CVA for example). The needle valve is disproportionate to my eyes - long, fat and heavy. On the bright side I likely won't need an extension to clear the cowl.

Does anyone proof-read anymore? Page 3 says use no more than 15% nitro fuel for break-in, then on page 4 it says no more than 10%. Might be the first engine I've owned where the instructions specifically recommend breaking in the engine on the airplane so you can test the whole tank/throttle/engine system. Last I checked a test stand is better for break-in because you don't have to worry about any of the additional variables.

Time for a trip to the test stand, I'll be running 10% syn/cas fuel with some extra castor.

Now I can get on with the work in the engine compartment, and with any luck in the air before the permanent snow.

Bladejunkie

Hey MJD,I'm putting one of these little guys together also,but I'm going with a OS .10 LA.I don't have any .15 size engines,so I'm going with what I've got on hand.I also have two OS .10 FSR's,but they are heavier than the LA's.I'm also going to mount elevator and rudder servos in the tail,as I"m already having CG probs.What servos are you using?I've got some Futaba 3114's I hope they will hold up to the nitro vibes.I'm trying to fly cheap on this airplane.I'll try to get one of my sons to download some pictures for me.All I have left to do is mount my servos,and plumb my fuel tank.Engine is inverted and completely under the cowl(except the muffler).

Later Jim.

MJD

My Feedback: (1)

Well, I am not sure about the sensibility of my servo choice.. I am using Hitec HS65HB's on each aileron, elevator, and throttle, and HS65MG on rudder. They "should" have more than enough torque. I put only the elevator servo in the rear, as I thought the nosewheel linkage would be a PITA with the rudder servo moved. So far, with the Magnum .15 in the nose, servo in the rear, and a 430 Lipo and Novak regulator in the rear of the radio compartment the balance seems pretty close. I had to put a 3/8" spacer behind the engine mount to get the prop hub clear of the cowl.. I glassed the inside of the cowl and that plus the thickness of the 1/64" ply and glass overwrap on the fuse front prevents the cowl from pushing on too far, it has maybe 7/16" engagement (at work, have to measure later).

Still debating on Jett 4oz bubble free tank or Hayes 3oz clunk.

Work has been hellacious for the last two weeks so progress slow, but a little job every evening or two and I am nearly there. It is still a very light aircraft, it should be a sporty .15 conversion. And I bet the .10 pulls it fine too. Again, I am pleased with the overall strength and light weight of the airframe.

Bladejunkie

Yeah I forgot about the nosewheel,so I'll be doing the same as you.I read the specs on the Fut 3114 servos,and it says not to use them on gas powered planes?The only other small servos I have are Hitec hs-81's,and I really don't want spend any cash on this project if I can avoid it.I only spent 85 bucks on the airframe,and I had everything else on hand.Do you think the Futaba servos will work?

Thanks Jim.

MJD

My Feedback: (1)

They seem too light to me for a .10 jobbie with large control surfaces. They might put some reasonable aero loads on the servo, and I would worry about the rudder/nose wheel servo especially. Then there is engine vibration, which is continually beating on the gears. Having never used them I don't have first hand experience, only looking at the specs. Maybe someone else can chime in here?

The HS-81 has almost twice the muscle, much better choice I think. They have been known to strip geartrains here and there but not sure if this is pandemic. There's another thread somewhere here with some talk about the 81's, maybe search that. Are they standard or metal gear? I'd lean towards MG for the rudder/nosewheel if you have it.

I am even concerned about the HS65's, though at 6V they have about 50% more torque than the Fut 3114's @ 31 oz-in.. which to me is more than enough. I am not worried about the torque level but the gear train. I'm using a metal gear on the rudder due to nose wheel shock load potential.

Bladejunkie

MJD,I've got two of each standard and metal gear.I was concerned about the weight,they feel about twice as heavy.I'll have to cut the servo trays a little bigger in the wings,and make a new servo tray in the fuse.I still need a servo for the throttle,I think one of the futaba 3114's will work on it.I know there's more vibes with nitro,but have you run a OS 10 LA,smooth as silk,once you have it broken in.Thanks again MJD.

Later Jim.

combatpigg

My Feedback: (3)

The HS65s have enough torque at 4.8 volts to strip gears if you are trying for 3D performance.
I think they will be fine for ailerons [but not 3D style]. I'd rather use a HS81 for elevator and rudder [if the rudder will be used for snap rolls, knife edge and spins..
The Futaba 3114s look so fragile, I'm not sure what they are good for besides tiny electric foamies.

MJD

My Feedback: (1)

This Contender is essentially a low wing Hots/Flite Streak hybrid - of course look at the manufacturer and designer and it is obvious why. Of course the Contender came well before the Hots, and I presume the Hots was inspired by it.

I'm not "into" 3D, I just want a sport ship with light wing loading, gobs of control authority and lots of power. And if I can avoid covering, all the better..

Mr Cox

I haven't had any problems with the HS-81 (or the HS-65), but I haven't used them for any steerable nose gear. I guess the trick is to have a spring saver for the servo, rather than a solid connection. There is a also metal geared HS-81 and it is now called HS-82 MG (more torque and metal gears).

bkhart

My Feedback: (6)

Anyone get their Mini Contender glow conversion done yet?

MJD

My Feedback: (1)

Oh.. about 85% done. Typical. We're about 4-6 weeks out from the flying season so the end of winter rush is starting - I'll get it finished.

I've been rooting through my servo collection recently and found enough HS-85's to go around, including one MG for the rudder/nosewheel. I'm much happier with that choice after looking again at the size of the ailerons and in fact, all the control surfaces. They are sturdy enough that I am not worried about the structure, but in terms of sheer size are definitely geared towards low to moderate speed antics.

Hefting the model with the Magnum .15 in the nose, gut feel says it will be fairly zippy with the .15, but it is easy enough to keep speed in check with prop choice. The nose moment is a bit long but it seems to be working out okay for balance. Only thing is how far back I can put the fuel tank.. I will use a Jett 4 oz so may try going back a bit to minimize CG shift with a full tank. Batteries don't gain as much weight when you fill them.

I would say a .10 would be a very pleasant choice for this airplane. Not sure if I posted it before but I decided on a 2s 430 mAh LiPO for Rx battery plus a regulator.

buzzard bait

Much better servo choice, I think. But I really think steerable nose gear is gilding the lily in planes this size. To the extent you steer around on the ground at all a fixed nose gear works fine, at least on grass. Then you don't have to worry about stresses on the nose gear damaging the servo gear train. Of course, with the MG you're fine.

I once used an HS-81 to control both ailerons on an old Skylark 56 powered by an OS 25 FP. It handled those loads just fine. Bigger plane and weighed 4 lbs, but slower of course, though it came down pretty fast in a dive. Anyway, your HS-85s will eliminate any worries about the servos.

Looks like fun!

Jim

airraptor

My Feedback: (66)

You would have been fine with the HS-65HB.

I disagree with CP as I have used these servos on 3d planes. These 65hb have a very strong gear train on them. I think you will break the servo arm before the gears strip. I have crashed a bunch of these only stripped the gears on a crash and that was when on a Tsunami plane 40 size with a OS 65AX on it. 140 mph into the hard dry dirt and not much left on any of the equipment.

Also I had a GP revolver with a Saito 91. While fly the firewall came off (common problem). The engine was around half throttle. The little HS-65HB held the engine on the plane as it was on the engine box and connected to the engine with a 1" metal push rod. The engine stayed running and as the plane rolled the engine would run up to near full power as the servo didn’t move the engine did.

I would put a metal gear on the nose steering but that’s it. I love these little servos. I think the best small ones Hitec has.


Now the HS-81-82's in plastic gear a crap. They will strip gears just by plugging them in. had it happen several times. The HS-85 MG and HS-87MG are my choice for next size up. Oh by the way I only buy digital HV servos now if offered.

One last thing the HS65's will run on LiFe power also.

buzzard bait

Well that's a good report. I am very prejudiced against Karbonite gears because I had them break when attached to rudders that had a tiller attachment for tail wheel, and that was the regular size HS-322. I switched to nylon gears and solved the problem. But lots of people say their HS-65s are very strong.

MJD

My Feedback: (1)

I figured I would be okay with the 65's, but while tidying up and sorting out crap I found enough 85's. The optimistic way to look at is that I can use the 65's on something else. The extra weight in the tail for the elevator servo will help too.

I agree with all poisonous sentiments towards the 81's.. I can barely be coaxed into using my remaining examples on throttles.

Glad about the 65's on LiFe.. I am changing flight battery on my Profi .061 sport racer to a small LiFe and I'd prefer to avoid a regulator.

So far I really like the 65's, and the price is low enough not to grumble too much.

What would be the recommendation for 1/2A size (aggressive 1/2A..) digital HV servos? I Haven't done any research on that yet.

airraptor

My Feedback: (66)

HS-5065MG digital. they are 33 dollars each but still a great servo. 30 ounces of torque also. way more than enought for any 1/2A. a bit heaver with metal gears.

Order six from tower with discount and free shipp they are only 28.33 dollars each. I order the HS-65HB in bulk also 12-18 at a time.

AndyW

My Feedback: (1)

I'd like to know the brand, wingspan, wing area and the empty weight as rec'd in the "kit". Also, has anyone flown one yet? Video? I ask because we had a beginner, at the time, that was having a devil of a time with a high wing trainer. When he finally demolished it, he brings out his .60 powered Contender, his second airplane. And yes, back then, we were all learning to fly on our own, no instructors.

We all cringed, but his response was, no guts, no glory. Crazy but that thing was slower than his .40 powered trainer and amazingly stable, considering. That fat airfoil and the force arrangement was pure genius. I'd always wanted to do a 1/2A version, 36" span at 12 ounces flying weight.

MJD

My Feedback: (1)

For a 1/2A version you'd want to go smaller. It's a big slab of wing. This one is 36" and I'd say a .10 would be fine but no less.

[link=http://www.towerhobbies.com/products/topflite/topa1025.html]TF Mini Contender[/link]

Plenty of video on YouTube of electric versions. No glow that I have seen yet.

AndyW

My Feedback: (1)

Thanks, MJD,

Going to have to look for the original plans then and downsize to suit. Sounds like 32" span at 14 ounces would suit a Norvel .074, just fine.

But here, http://www.youtube.com/watch?v=lrOTQ...emb0Ckt0lKao3A we have it doing 19K on an APC, 7 X 3 ,,, not too shabby.

My thrust/HP calculator says that's a static thrust of 2.6 lbs at .35 HP and speed of 54 MPH. [X(] Shoot, that'll fly the stock kit, just fine, I think. Maybe I'll pick up a kit.

MJD

My Feedback: (1)

2.6lb you say? That seems pretty impressive for an .074.

In that case it might be fine. I was going by heft and gut feel - to me this feels like something that would be a nice flier on a .10 and pretty perky on a .15. But I have no experience with the .074 so don't have an opinion on it. Plus, I tend to gravitate towards excess power.

AndyW

My Feedback: (1)

How about 21K on the same prop? http://www.youtube.com/watch?v=Xseov35rRQM That's 3.18 lbs on the same prop.

Keep in mind that the .074 shown is NOT typical, with a number of mods applied along with the tuned pipe. The OS .10 is over bored by installing the piston and liner from the Norvel .15 making it about a .15 engine with the weight of the .10

It would be nice if the manufactureres would offer them with the power they're actually capable of.

The OS .15 actually has the SAME crank as the .10 with just the stroke being longer. That is one strong crank for the .10,, overbuilt.

I have plans to install the .15 crank into the case with the .15 piston and liner. This will make it a .19 with the same weight as the original .10 [X(]