More SuperrHots Fun! Throws, more engines, radios, angst...

If you have a prop clearance issue try putting two smaller props on your big. I did this years ago on a plane I scratchbuilt from Goldberg Eaglet plans. A 25 would have been the largest reasonable engine to put on this plane, so I put a 40 FP on it. A 10 inch prop would have been way too much, so I put two 8x6 props on crosswise. It worked beautifully. Perhaps you could do something similar with your plane if you want to use a 120.

By the way, I agree with you about Tower's website. It reminds me of getting directions from somebody in New England. You can't get there from here.

.........snippage.....................

Very interesting idea. Did you have any problems with the 2 props not staying in the proper 90 degree orientation--slippage?

No slippage problems, but I couldn't use a plastic spinner. I used to flip that engine with a screwdriver handle.

I never was too concerned about having them at exactly 90 degrees anyway. Most of the time they were at about a 75 degree angle. The only tricky part about this idea is finding the exact propeller load that the engine needs. I got lucky on the first try when I did it. You may have to try a few different props. Come to think of it, 2 different sizes may even work just fine if you happen to have them lying around anyway.

I'm a bit unclear as to why you thing the Superhots is a "dog" The thick wing is quite draggy, but the performance could be whatever you want depending on pilot choice and engine selection.

Personally, I put an OS .91 Surpass 4 stroke on mine with a nice APC 14x6 "pattern" prop. I was warned ahead of time that it would be a "slug", but it wasn't, It was my first excursion into the world of "3-d" performance.

Admittedly, it wasn't a speedball, but couldn't be beat for exploring the world of flight right at the edge of the stall. It was plenty fast for any normal flying, and had enough excess thrust to provide the proverbial "unlimited vertical"

Now, If you fly "digital throttle" mode, you would certainly be happier with a nice .90 2 stroke turning a 13x8 or 13x9

It's been a dozen years since I've flown the SH. Frankly, I do not remember exactly why I concluded that it is a "dog" (bad word choice), but that is the impression that lingers.

I initially flew it with a Royal 46---what I had on hand. Naturally it was underpowered and sluggish. What was interesting is that I replaced the Royal with an ASP 75 and distinctly remember being impressed by disproportional low increase in performance, but I got few flights with the ASP due to starting problems. Do you have the Midwest, detachable wing SH?

In any case, I'm getting back into the hobby and it's the only plane I have currently. You address engine choices, and indeed this has been an issue, discussed in a previous thread. I was initially thinking of cramming an OS 1.20 AX on it, but am now thinking more along the lines you describe--a zesty 4 stroke, perhaps a Saito in the 90 to 120ish range, or a 75-90 2 stroke. Tower 75, OS 91, etc.

I guess you don't have prop clearance probs swinging a 14" props? I'm thinking that thing needs thrust, consistent with your positive Surpass/APC impressions.

There is some consensus that the hitherto Rock of Gibraltar OS is not what it used to be. It seems that most of the less expensive brands are plagued with this or that problem. It was much easier before the internet explosion---too many opinions.

By the way--do you happen to know the recommended throws for the SH? The manual is long gone. Thanks for your reply. Dave ("Digital mode" ... ??)

I did replace it as my main plane rather quickly with a Lanier Stinger

40, which was even less impressive, but that could have been due to insufficient power -- Enya 45 with Pitts style Muffler.

I had the SuperHots from Midwest, built up from a kit. If I remember correctly, the instructions called for anything from a .46 to a .60 two stroke or equivalent 4 stroke.

As I recall, the fore / aft balance worked out nearly perfectly with the OS .91 four stroke up front. Prop clearance was never an issue even with the 14 inch prop and relatively rough runways, I DID use 3-1/2 inch diameter soft foamie wheels.

I haven't bought a new engine for some time, so can't comment on whether the newer OS are up to the older standards now, but some of the last ones I bought were a bit disappointing in the quality department.

As to the recommended throws, I have no Idea, and haven't had time to dig for the old instructions. I built mine in 1996, first flew it on Sept 25 of that year, and got more than

300 flights of 8 minutes or longer out of it before I killed it exactly 10 months (to the day) later through a combination of poor maintenance and pilot stupidity. On the last flight, the throttle, elevator, and rudder all suddenly changed in their response to stick movement. Post mortem examination revealed that the main servo tray was broken loose, and judging by the wear patterns, had been mostly loose for some time. My Bad, a mistake I have not made since that time.

If memory serves, the rudder authority was "ok" but certainly not excessive with the stock rudder, and the throws set at "all you can get" I always set the elevator to excessive amounts to start out with, and then reduce it just to the point that you CAN pull max elevator and not snap out of a loop, but have no idea what the actual numbers might be now. the Ailerons on this bird seemed a bit small, so I'm certain that I probably had them turned up to around 3/4 in throw at max stick deflection.

KEEP IN MIND that I was flying mostly at or near stall speed. FAST flight at MY preferred settings could make things "interesting"

on the digital throttle thing, In digital control, there are two states, "0" or off and "1" or on I have noticed a LOT of people seem to regard the throttle stick as having only two positions, idle speed and WFO once they are ready for takeoff, the throttle goes to full, and STAYS there until they are ready to land.

By way of contrast, some of us tend to get a lot of servo action on the throttle, and rarely maintain full throttle for more than a couple seconds at a time.

to each his own, bob

So I should take my throttle servo off of channel 5? :) mk

Ok, I finally got a chance to dig out the construction manual

For the Midwest Super Hots Kit #157

the recommended throws were

Rudder 1-1/2 inch left 1-1/2 inch right

Elevator 3/4 inch up 3/4 inch down with dual rates, High rate is 7/8 inch up 7/8 inch down

Aileron 1/4 inch up 1/4 inch down with dual rates, High rate is 3/8 inch up 3/8 inch down

bob

Bob, Geez....that is a tremendous help. I would of had too much aileron and not enough elevator.

Does the manual happen to show the CG and the thrust line? Also--I can't remember if the engine should be mounted for any down, up, and/or right thrust. Thanks again for the info and help. Dave

Bob, Also--the FS-91 II Surpass 4s is looking more and more attractive. I assume you are using the non-pumped version. Do you have experience with Saito? Looks like the Surpass may be easier to live with--requires less nitro, for example. Virtually all 4 strokes at our field are Saitos or gassers.

I was initially apprehensive about an expensive 4 stroke and in desperation ordered a Tower 75, which looks to be a high rpm loving and screaming loud 2 stroke -- probably a truly bad selection.

Guy's experiences with the OS 91fx 2s are still all over the place, despite the backplate NV mount re-design.

Maybe I should send the Tower back and shell out the cash for my first

4 stroke. Dave

Tower shows the tower 75 to weigh 4+ OZ less than the OS 91. I'd go 2Cy, that 75 may be just the thing for the SH. BTW, that SH won't be a dog unless it gets too heavy. mk

That's a good point. Light planes fly better than heavy ones. You can often make a plane have "lighter" performance by putting a smaller engine on it.

I had an RCM Advanced Trainer a few years ago that I had built with the wings shortened a few inches and no dihedral, to take advantage of some

48" spar stock I had on hand. I thought it would be super cool with a 48 Surpass, but its turning radius was terrible. It was fast enough, but not very spritely. Unfortunately (fortunately?) that engine had a crankpin failure, so I put a 40 FP in its place. The plane came alive! Its flight performance was better in every way. To this day, that plane is on my short list of the best planes I've ever built.

.....now that I'm thinking about it, I don't really have a short list of the best planes. There are a LOT of really great planes in the RCM catalog. But the point is that lighter engines are usually better, even if they are less powerful than the heavier alternative. My Miss Bikini had a 20 FP on it. When I build another it will have an engine in the

20 FP weight class, not a ball bearing 25.

Back to the Super Hots, if you already have the 75, bolt it on and see what you think. I'll bet it's just the ticket. How much does the plane weigh, overall? 4 or 5 ounces is a noticeable percentage of total weight in a model plane.

Guys, With everything but the engine installed, it weighs about 5 lbs. That's using a fishing scale.

I used a CG balance to determine how much the engine must weigh to balance on the main spar--which I THINK is the recommended CG. ...

25.5 ounces. This accounts for prop, spinner, mount, and approximate CG of the average engine. The OS 90 size 2 and 4 strokes are about this weight. I may have to add nose weight with the Tower.

I did order a Hayes long mount which may solve any possible prob. Nothing worse than adding dead weight to a plane. Dave

"DaveH" wrote

Yep. Can you move the receiver battery more forward? If the battery is more forward than the CG, you could go to a C or sub C battery, and perhaps a 5 cell pack, so you get something useful instead of lead for the weight.

Unfortunately, the CG is printed on the plans, and I have not had enough time to go back and dig through the archives for them.

IF memory serves correctly, thrust was 0/0 no downthrust and no side thrust. At least, I mounted my engine as square as I could get it to the firewall

On my plane, I used the basic non-pumped .91 surpass with good results.

I have also used the Saito successfully on several other projects the Saito is a fair bit lighter in weight, Has comparable performance, BUT it is a bit fussier about needle setting, and a bit thirstier under the same conditions, Also, the Saito will protest more if you try to put too much prop on it.

Most of the guys here ran .90 two strokes on theirs, but I remember at least one which flew VERY well on one of the old Italian SuperTigre .60 engines

In MY Humble OPINION prop choice is far more important than the engine choice IF you match the prop to the engine and YOUR PERSONAL flying style, You can use a fairly wide range of engines on this plane.

And if you end up just a bit short of power for your liking, or you want to change the engine response, there is always the option of adding a Mousse Can Pipe

Lets discuss a mousse can pipe for a .60 or larger. I tried a 12 alum. Bud can but it seemed too small. Anyone know of a suitable, light can for this purpose? mk

Part of the beauty of the MCP is that they are so non-critical in their nature, (Not like SWMBO in that regard) Personally, I try to choose a can whose volume is somewhere around 20 to 40 times the nominal engine size. This has worked out for me on everything from an OS FP-40 on up through an OS FX-61, an ASP .90, and even a Webra 1.20. On the Webra, I used a can which is around 2-1/2 OD and has a straight sided length (ignoring the rounded top part and the fat punt in the bottom) of around

6 inches. gives me a can volume to displacement number of around 24:1

One of the nice things about these cans is that with a little (very little) effort they can be had for free.

Almost every town with a population of 200 or more has at least one professional hair dresser. I have found that most of these people are more than happy to save you a few cans of various sizes,,,, if you ask politely.

In most towns of 15,000 or larger, they often have a "Beauty College" or "Beauty School" or some such thing, They usually empty those nice seamless cans at an alarming rate, and will usually save a few for you,,,, if you ask politely.

The hazards of obtaining cans this way are:

1: being seen by your macho buddies entering or leaving a beauty shop 2: most of the people saving the cans for you do not differentiate between the drawn seamless aluminum variety and the seamed steel cans, But you can sort them when you get them home.

The real challenge for me is to resist the temptation to put an outlet tube on these things that looks big enough ;-)

Ok Bob---thanks, Dave

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