AA5BY

Speaking of waiting... I had a 15&33 GX coming....

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ozzydude

mattnew

My Feedback: (2)

anybody get their 15GX running over the weekend?

Fl_Matt

Hi Pete,
Would the 15gx be a good fit in the H9 .50 Corsair? I was going to order the 10gx but I am not sure if it would have the power to fly it with authority, but at the same time I don't know if the 15gx would be to large in size or weight to fit the plane. What are your thoughts? This post was directed to Pete but I would love to hear all opinions.
Thank you,
Matt

Edwin

My Feedback: (2)

I'm putting my 15gx into a TF corsair. I did a side by side comparison to an old os.91fs and they are pretty close size wise. Just an opinion, but I think the 10gx is a better fit for the .50 sized corsair. Unless you're looking for screamin low runway passes.
Edwin

TimBle

The 15GX is a .90 size petrol engine. It is not going to be down on power compared to a 91FX on 10% nitro containing glow fuel. I have found that size engine to be way too powerful for .50 size airframes. Open the throttle and the left wing drops and any thrust misalignment is exaggerated by the extra power. Overpowering those warbirds just exaggerates any bad tendencies they have. The 10Gx is plenty power for that size airframe.

The 15Gx and 20GX are really suited to the .60 and 1.20size warbirds respectively

Pete Bergstrom

Matt,

The 10GX was designed to power models exactly like the .50 size corsair - and it flies it with plenty of authority ... giant round loops, fast passes down the runway ... there is nothing to apologize for when combined with this model. By choosing the 15cc vs the 10cc you will be adding additional unnecessary weight that would ultimately detract from the performance of the airplane with a higher wing loading. I think you'll be real happy with the 10cc in that airplane.

Pete

Fl_Matt

Thanks everyone for the input. I have the 10cc on order from my lhs  . Hopefully horizon will be shipping them out soon !

David Eichstedt

My Feedback: (17)

Looks like we'll be shipping the 20GX tomorrow.

AA5BY

I've started efforts to re-power an aerobatic model from Saito 1.25 to Evo 33. The plane has hardwood rail engine mounts hence why the Evo 33 was chosen and they have perfect spacing of 1- 15/16" for the engine so as expected the engine dropped in. The Saito 1.25 doesn't have that kind of width but the beams were originally set up for a YS - 120.

The muffler however has some clearance issues with both the muffler wrap around header and the muffler body. The body will not be much issue, just cut away a little of the lower fire wall but the header clearance will need a cowl blister. The plane was set up for three degrees of thrust which has the beam mounts shifted to port exasperating the clearance problem.

A cowl blister isn't a terrible issue as it will give opportunity to close up the hole used by the Saito muffler header and the cowl was in need of a paint job anyway. I'm thinking one of larger plastic easter egg halves will make a good mold to lay the glass into.

AA5BY

The re-powering project is troubling me. It will add at least 12oz of weight plus cause cowl issues so I'm thinking now the 33GX will be saved for another project.

btw, the drawing shows the rail mounting bolt spacing across the engine to be 50mm, but it is somewhere around 58-60mm.

I'm not sure which direction I'll go... maybe the 20GX but I need a dimension before deciding. Can any one tell me the distance from the engine center line to the furthest point of the exhaust header?

AA5BY

Having put the 33GX re-power project on hold, attention turned to the other re-power project, replace an HB-61 in a Mustang with a 15GX. The install was mostly a drop in and fuel tank change. The engine did need shifting aft on the mount and fortunately enough so that the holes were well away from the previous. The thickness of the radial section of the mount had to be reduced slightly to set the spinner properly from the cowl and that places the tear shaped head very close to the fire wall... but it worked.

The plane was also upgraded to a LiFe battery, an IbEC to control ignition and a 2.4 RX.

The 15GX leaps to life quickly just as the 10GX. The initial idle is better, not having the drag and tightness of a new ABC configuration. The engine is also smoother running and in fact notably smooth for a gas engine.

On the sixth five minute run... it was given burst to 9k and above and chopping the throttle quickly it winds down quickly and seemed near stumbling although it never quit. A one second delay was programmed on throttle down and that worked well with the throttle coming down to a very good idle.

I'm impressed with the smoothness, good idle, throttle linearity, easy starting, and miserly fuel consumption. The first four five minute runs were on a single 8oz tank albeit they were limited to 6k alternating with periods of idle.

I've yet to dial in the HS needle to determine max rpms. A few more engine runs will tell.

As done on the 10GX, Ultra Copper RTV was used on the muffler without any leaks. Now time to re-tighten to ensure that any stretching is taken up.

AA5BY

15GX flight report.

Wow, what a sweet running engine. It runs smoother and starts and tunes easier than the 10GX. I like the 10 but I love the 15.

I've a 20GX on the way to replace a Saito 125 and hope it runs as sweet as the 15GX. The 33GX is laid back for a future project, perhaps a Great Planes Super Stearman waiting in a box. IIRC, those who have built it have claimed that it needs extra nose weight... so the 33GX might be a good choice for it.

Somewhere, I've got to find some hanger space.

Power of the 15GX seems a little more than the HB.61. It does not have unlimited vertical but climbs very high before running out of steam. The Mustang the engine was fitted to weighs 9lbs 10oz and has a 62" span and I'd guess thrust is about 9lbs with the 14x6 prop.

ozzydude

Good deal! Thanks for the update!

AA5BY

Pete... if you monitor this thread, a suggestion about the pressure tap on the 20GX. From the factory, it is located so that after and inverted engine mounting, the tap is located right on top of the muffler. As you might imagine, many builds will have the muffler sitting below an engine box or offset or cutout and boxed in section of a firewall. The tap then is very inconvenient. It seems to me that it would be better if the tap were forward some, perhaps 30° toward the engine to provide a reasonable path for the pressure line to the tap.

rhd-RCU

My Feedback: (36)

Put your own in and plug the original.

Fl_Matt

When will the 10gx be back in stock?

AA5BY

RD... I've worked it out but it is one of those things with a new product that should be brought to the attention of the designer to make it better for everyone.

rhd-RCU

My Feedback: (36)

Sometimes that is almost impossable.

Lifer

My Feedback: (1)

If the 20 uses muffler pressure, and doesn't have a carb with a pump, inverted mounting will lead to flooding/siphoning issues, will it not?

AA5BY

The 20GX does require muffler pressure and has a carb similar to the 10&15 GX where a regulator is part of the carb but not a pump. It therefore requires a typical fuel tank installation similar to glow, ie right behind the firewall and approximately centered on carb.

As to inverted flight... exactly similar to glow fuel supply with the big difference that gas requires only about 1/3 the rate of fuel consumption as glow. Typical to glow, if the tank were considerably below center of carb, a rich setting would be needed to draw adequate fuel when upright and when inverted, the extra gravitational force would cause the engine to go very rich as well as the reverse situation... if the tank were too high when upright it would require the needles set lean and then when inverted they would be very lean.

My guess is that because gas uses far less volume... tank height differences between upright and inverted would magnify the effects and therefore a regulator is needed.

gilanne

My Feedback: (4)

I Flew my GP Escapade 61 Evo 15 GX combo Yesterday. After a 20 minute brake in on the ground. It was still set on the rich side but ran and flew great I used the recommended 13-6 prop The low idle was really impressive. My tach died so I couldn't get any numbers. I think it will be a winner and am looking forward to getting more tome with it.

gilanne

My Feedback: (4)

correction to the previous post. I ran two tanks of fuel on the ground. The 10 once tank ran the engine for 20 minutes, with fuel to spare, alternating from idle to half throttle. The ignition, which is about half the size of most, is mounted next to the fuel tank. Both batteries are mounted about at the CG and the plane balanced perfectly.

David Eichstedt

My Feedback: (17)

We started shipping the 10GX again today. Plenty of stock to cover all backorders and then some.

ozzydude

Thanks for the update!