Hi All,

I'm a neophlyte RC'er with a couple of questions.

1. I'm looking to buy a tachometer to match my props with my engines and planes. Any suggestions? Like everyone I like smaller and cheaper if it works, so is the new Hangar 9 Tach any good for $25-30.

2. How closely does the inflight RPM match that of the measured static RPM? The real question, if I'm at max RPM on the ground, do I need a prop with a bigger bite to keep from overspeeding in the air?

3. What about on board tachs?
It seems a natural to place a tach sensor in the cowling (maybe an emitter as well as receiver), just behind the prop, route a couple of wires back into the fuselage to an on board microprocessor that record the max RPM, and maybe gives a histogram of the whole flights characteristics...

Any ideas on what works best as far as light wavelengths? UV, visible, or IR?

Thanks in advance for any help you can provide!

Cheers!

Cub

Hi Cub,

Replying by the number:

1) I never saw a Tach That was "off" . That covers the original Heath Kit Thumb Tach (before your time) right down to the H9 Micro which I now use. It gives the same readings as the larger variety. Matching the engine /prop. set up will be done through in flight experience.

2)Airborne you'll gain about 1000 rpm + or - . DO NOT try to compensate with your ground settings which should be at max for each prop size.

3)Can't help you with on-board Tachs. But you better get one that shouts the numbers out as you can't take your eyes off your plane.

Repeat after me KEEP YOUR EYES ON YOUR PLANE !!!

Hope this helps.

Thanks for the feedback.

I went out and bought the new hangar 9 Micro Digital Tach. It seems to work fine.

Regarding the ground prop setting ...

(a) if I'm set at max rpm for a prop on the ground, (b)which also happens to be max rpm for the engine, (c) if I'm going to gain 1000 rpm in the air, then (d) I need to change props for a lower ground setting ... no ???

As far as the on board tach I was thinking post flight, on the ground, motor stopped or at idle, then retreiving the information.

I know all about keeping my eyes on the plane ... but thanks for re-inforcing the idea.

Cub

I've flown pattern for many a moon and while my present choice is not a pattern design as drawn a few mods. and it is really quite capable. During this time I've never seen an engine "come unglued" --- seize because they were set too lean. yes but scatter never.

Assuming you have the instructions that came with the engine, a set of prop choices should be listed . Normally this will include one for break-in and then a range for use after break-in.

I go straight to the normal range, set up idle so it is reliable,
set the top end for all it will give (carefully). Then back off a couple of clicks ie. richer and break it in in the air. The only bench run engine I ever owned was a slug of the first magnitude.

Since then and the many moons I referred to earlier, I've had nothing but performers with no problems save for one or two getting a little tired after 60+ gallons -- that is completely factual !

I would recommend the same for you. Do it and don't worry !about anthing, save for flying the airplane.

Ah, experience. That all sounds like good solid advice!

What's your usual choice of engines?
Any particular manufacturer you like?
Any you avoid?

Of course I've never been able play with anything without wanting to fiddle with it ... and if I can blend my two of my hobbies (RC planes and computers) so much the better.

Again, thanks for the recommendations!

Cheers!

Cub

Your local club members will be a better source for the brand you choose, if for no other reason than the support they can offer . Choice of engine brand is somewhat subjective and there are many fine performing brands available.

Answering your questions directly:
I switched to four stroke for the sound and raw torque and the change itself . Currently I'm flying the Saito 150/180 singles.

I assume that you are looking at glow, two cycle as this is the standard over time . Limiting my comments to the brands still available, I have had good results with Super Tiger, Enya, Webra, and OS. Each is more than good. While Enya is a great engine the importer is lousy and parts are a problem. Webra is a bit pricey but excellent. ST lacks external appearance (and always has) but they do run. OS has the appearance as well as good performance. There are others.

The only brand I really dislike is Rossi .

Good luck.

Four cycle is a different story. YS and Saito are the choices there .

An interesting group of 2 stroke engines ... it seems like they are all on the upper end of the price scale (with Magnum and Thunder Tiger on the lower end of engines I'm a little familiar with), but I'm assuming power and reliability goes with it.

Enya has been around for a long time. Back when I tried control lines in the early 70's Enya were the hot engine of choice. They had a reputation of being really hard to start and to break in ... I haven't heard that about them since recently venturing into RC.

With one exception that I can think of, it seems like just about every one in my club flies OS for mid sized 2 stokes. Of course, this could be because the best local hobby shop has as a large selection of OSes. I'm not even sure they have anything else on hand for .20 to .60 2 strokes.

While I was shopping for my nephew, I went ahead and bought myself an OS 46 FX. I bought a used low wing WM super sport with a TT 46 Pro on it. I figure having a spare engine on hand to swap around couldn't hurt. If I break it in on my trainer on the SS, I should have an engine ready to go that I can trust for my 3rd plane.

Cheers!

Cub

You made a good choice. The fact that many other club members and your LHS use/sell them is worth it's weight in gold. Plus the OS FX line are fine engines !

The Enya starting problem is a bad rap. Mine (two examples) started easily and proved reliable at all throttle settings for over 100 gallons . (Pattern Fliers enjoy practice). Remember, NO two cycle glow wants to start hot. That's where electric starters come into the equation BIG TIME.

For the record, in RC the worst problem you can encounter is a Radio failure ---- today that doesn't happen very often, if you just exercise some common sense. The next worst problem is a balky unreliable engine ! That problem is still with us as it is usually the guy twisting the needle who is at fault.

Best of luck to you.

Incidentally, one last comment: airplanes (regardless of scale) and women do not mix well . The same is true for race cars (full scale) with which I also have experience .

Back when my friends were trying to start their enya's for the control line planes, it was all by hand, no starters involved. It's quite possible that a electric start would have been all they needed.

I'm sure you have your reasons, but I'm not so sure I agree with the airplanes and women mixing comment.

What kind of cars ... open wheel, stock, drag, or salt flats?

Drag and open wheel. Nitro Karts on road courses and ovals. One of our guys, Mickey Rupp, finished in the top ten at Indy. Another friend Eddie Johnson finished in the top five twice and the top 10 a couple of more times' Foyt and Parnelli were running then.

Eddie Johnson and his wife were killed in a crash of his single engined plane. Mickey Rupp I think is still around. The last I heard he had a P-51D tandem conversion and was practicing long spin downs in an aerobatic zone in western Ohio . I have since lost contact. We were racing friends not personal friends .

Next time you're in a bookstore pick up a copy of "A Driving Passion" by Mario Andretti . Turn to page 53 and you'll see Mickey leading Mario in a Sprint car race. Mickey is in the car in the center. I managed to ace Mickey one time only, on a short oval . Obviously I still remember it .

As for women and airplanes I think my averaging 30 gallons of fuel a year, might have had something to do with it .

Ah Mario ... I wonder how many years I suffered along with his other fans every Memorial Day when he was ever so close to winning his second Indy ...

Personally, I've got the reflexes of a two toed sloth, so racing (except maybe for bracket racing) is pretty much out of the question. I do like the machinery however.

I see your point regarding women and planes. Burning two gallons at 6 oz at a time has taken me a while ... add in all that chatting and gawking and 30 gallons a year would really eat up the time. Maybe the next time you could try sticking with a 30 gallon limit, and get a twin with really thirtsy engine!

Cheers!