xanaphyst

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DNU coming together. An enjoyable build. It's easy no to recognize how common the build methods are amongst many of the common planes here.

xanaphyst

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The business end is a new sure start and I noticed during the breakin today that the needle would twirl around on its own and not hold a setting. It was also fairly bent. I swapped it with a killer bee needle
and rigged up this getto retention method which was cheap and worked like a charm. The 2 oz. tank from haynes gives it a nice long run. On another note the 2 oz. tank from haynes is lighter than the
1 oz. tank from dubro.

xanaphyst

My Feedback: (17)

Back to the Ranger. Here is the exhaust extensions installed. Didn't come out too bad as I was able to retain most of the engine cowling/cheeks or whatever its called. I wish the wind would give way but it hasn't slowed for the
last couple weeks. Maybe I'll get a break soon and can put this thing in the air.

xanaphyst

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And now the DNU. Finished this one up as well and it is waiting for the wind to stop. My daughter decided it needed a marsh-mellow with pink hair on the tail so there it is. I decided to try a power jack
switch on this one to see how I like that setup instead of a conventional switch. The solder job on the jack came out great and I connected the battery straight to the jack as to eliminate one more
failure point. I took a lot of time to make the radio bay very neat and clean.

xanaphyst

My Feedback: (17)

I mounted up a bunch of engines so that I could make some noise. Some of the engines had not run in a long time so I decided to fire them off. The little MP Jet diesel is a .040 classic
that nearly made my arm fall off trying to start. Once I took my remote fuel tank off and installed the little fuel bowl that came with it success was found. It can be quite a pain trying to
find the right compression and needle to get it on it's first run. I do have to say that after the sweet spot for the initial run was found, It has started easily and ran smooth. It turns a 7x3
at 7800 but I do not know if that is good or not for a engine like this. The box with the 3 cox engines was part of my trial of new techniques. I've decided that I will learn and incorporate
new things in my model building and this box is fiber glassed which I had never tried before. I tried a few different kinds of cloth, tapes, carbon, and kevlar. This was a lead in to some
vacuum stuff I'm going to start trying.

xanaphyst

My Feedback: (17)

I drank the 2.4 kool aid and thought I might point something out....The AR400 spektrum receiver is right there with the GWS FM's as far as size. I thought that was really good.

ffkiwi

You can't have a lot of diesel experience then-the MP Jet Classic 0.6 is the easiest starting diesel around-bar none-better even than the much loved Mills 75. They start and run extremely easily, throttle well by backing off compression, and handle a good size of prop. They're not a Cox TD or Norvel though so don't treat them as such. A 7x3 is about as small a prop as you would ever want to use on one-and mine (I have 6 of them-and some of those I've had since the mid 1990s-so I have a LOT of experience with this particular model) are generally turning an 8x4 or 8x3 prop. I would say, based on my extensive experience with them that 7800rpm on a 7x3 is about bang on-and as close to peak power for this engine as you could want. Mine are usually operating well backed off at about 6000rpm on the 8x4s for slow puttering sport F/F use. FWIW these engines can be fitted with an R/C carb if you so wish-CS make them in two sizes for their small 'Mills style' diesels. MP Jet don't offer the Classic with an R/C carb. About the only feature I don't like about them is the single screw beam mounting setup-four hold down screws are a much better idea.
Finally-a word of warning-or rather caution is probably more accurate. Ex factory, these engines are set up very tight in the bore-almost 'squeak tight' like an ABC engine [which they're not of course]-they do need a proper run in-using the classical method of a big prop, rich running, for short periods of time, allowing cool down time between runs. The instructions specify a run in fuel of 40% lube-which seems outrageously high. In this instance the manufacturers know what they're talking about-follow their recommendations.

ChrisM
'ffkiwi'

xanaphyst

My Feedback: (17)

ffkiwi, you are correct as I have almost no diesel engine experience with models. I did try the 8x4 today that you like and it seems to work well. I can't believe how long these things run on just a little fuel. I also started thinking about the
RC throttle you mentioned and almost ordered one. I decided to try making my own throttle first. The following picture is what I came up with and it is very simple and very effective. It is nothing more than a Blue/Yellow Gold-N-Rod
from sullivan. The outer blue part is an exact tight fit on the venturi inlet of the 040 classic. I installed a short piece on the venturi with ONLY one very tiny idle hole drilled in it. I then started the engine and put my finger over the large end
hole which left the engine to only suck air from the idle hole....the engine died and this told me that the idle hole was not large enough. I drilled the idle hole a little larger and tried again, and again, and again until the engine would fall to a nice slow and steady idle when I put my finger over the large end hole. From this point I now knew that the engine would idle great with just the idle hole open. I then drilled small throttle holes going twords the large open end. I repeated this until the engine could run wide open with just the throttling holes and idle hole open (by holding my finger over the large open end.) I then inserted a yellow pushrod into the blue tube with the holes. As you know pushrods are not an airtight fit so I glued a small rubber piece
to the end to make a good seal. With the push rod installed I could throttle the engine perfectly. I never used the pushrod to cover the idle hole so the idle was always exactly the same. You could make 20 throttles with one pushrod likely. It worked so well I couldn't believe it.

ffkiwi

Well you've picked an excellent engine to learn the tricks of the trade on. There's no doubt that diesel handling is different to glow handling, and there is a learning curve-but once you acquire the knack, you never lose it. You need to learn the subtleties of the interplay between needle and compression adjustment-and the differing notes you get with the various combinations of 'rich-undercompressed' 'lean-overcompressed' and the alternate combinations 'lean-undercompressed' and 'rich-overcompressed' [they all sound different] ....and then the sweet sound of needle and comp set just right!

Rear intake diesels (including disc valve ones) lend themselves to simple throttling as you've done. Just don't expect a 2,000 rpm idle like a good glow-and the pick up will not be as clean as a glow either. The issue with diesels is that the longer you idle, the more the combustion chamber cools down, so when you open the throttle again the ignition point (which is influenced by the temperature) is now incorrect-and a period of misfiring will occur as the engine settles down [this will only occur after extended periods of idling]. In theory, if one had an R/C adjustable compression screw (and these have been produced by Davis in the past) you could readjust the compression in flight to compensate for this-but it's an unnecessary complication-and requires a relatively loose contrapiston fit-which has disadvantages in other respects.

You'll enjoy the quality, longevity and easy handling of the MP Jet Classic 040 once you get used to it-it really finds its niche for vintage, scale and sport FF-and if you've got a throttle, makes a half decent park flyer engine-without much noise. It really likes the 8x4 size-and is especially pleasant on something like a Cox or Topflite 8x4 nylon.

Your clever throttle approach is a variation on what has been done in the past for some Cox reed valves-Ace R/C sold a simple reed valve throttle like this back in the early and mid 1980s

......and if you decide you want a lot more poke, then the MP Jet 061 diesel is a very impressive little powerhouse, available with a proper R/C throttle as well as std venturi version (also exists as a near identical glow-in both std and R/C but the two types (diesel and glow) are not interconvertible. )

ChrisM
'ffkiwi'

xanaphyst

My Feedback: (17)

ffkiwi........I'll pick up a few of those cox 8x4 props over at Cox International to try out. Do you have a good model in mind for park/RC flying? I've been wanting to do a Texaco, oldtimer, or converted freeflight.

MJD

My Feedback: (1)

Tomboy! Or any 1/2A Texaco model.

But there are many other choices. On the lazy side of my personality - much larger than the other side - the Sig Kadet EP strikes me as a potential 1/2A lazy putt putt conversion possibility. Pretty light construction based on the thorough fondling I gave one in the hobby shop last week.

Here are a few 1/2A Texaco kits:

[link=http://brodak.com/spirit-of-yesteryear-kits]Brodak - SOY line of kits[/link]

ffkiwi

Xanaphyst-I'd try and get the white or black nylon Coxes if you can manage it-the grey rigid ones break too easily-and the Classic prop shaft is very thin! A bit of prop flexibility is probably not a bad thing!

BMJR models (www.bmjrmodels.com) has some suitable laser cut kits....certainly for Texaco, Old Timer. I'm not sure that a typical electric Park flyer would be quite so amenable to fitting an MP Jet Classic to-simply because they're usually a lot more lightly built. There is a 42" Texaco plan around (Carstens IIRC) for the Buzzard Bombshell that would be a good match. Any 1/2A Texaco model is going to be a good fit with the Classic-as you're operating right in the same regime as the Cox Texaco-about an 8" prop and 6-7000rpm. You could also scale up any of the 020 Replica vintage kit plans to around 42-44" span-but you'd need to make structural alterations (beefing up around the nose area, for example). I have the KK plan for a 1/2A Texaco Playboy Snr that I've often considered fitting the MP Jet Letmo 0.6 replica to-(the Letmo being the inspiration for the MP Jet Classic)-but at 45" span it is a wee bit on the large size.....but I suppose if it flew on a Cox Texaco in the past, than an MP Jet should fly it.........

There are a few useful accessories out for the MP Jet Classic-a spinner nut (which only really improves the look), a larger 3cc metal tank, a clear view tank, a 'T-type' compression screw, and a very useful machined radial mount-which certainly makes the job of mounting a lot easier on designs originally set up for Cox reed valves. Its not a perfect world though-you still have to accommodate the venturi and tank somehow behind the rear face of the radial mount.....though of course you can choose to use an external tank, and then you have the option of rotating the venturi and needle valve assembly to any angle you choose that's convenient.

See pics below. Not all vendors will necessarily stock the various accessory items. The props shown are not current production-but still readily found on Ebay, and well worth the effort spent to obtain them-they'll certainly outlast the more rigid modern type, and are a lot more forgiving on the fingers! They also tend to have thinner hubs than modern types, which makes them better suited to older engines which often have shorter prop shafts. The DC prop shown fitted is virtually indistinguishable from the Topflite one-other than the embossed writing......so close in fact that I suspect some form of licensed copy.

The sport model shown-currently on the back burner, would quite happily convert to R/C if needed, and is almost entirely built from medium 1/8" balsa-apart from obvious bits like engine bearers and firewall. Very durable, easily repaired-this one is the third built to this size (the original 'Humbug' being 30" span, built from 3/32" , and flown with a Cox Pee Wee)

ChrisM
'ffkiwi'

PS....the 'Super Sniffer' would also be a good match-it used to be kitted by Midwest-but that was long ago-the plan though is probably still available from one source or another

MJD

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Here's a Sniffer for sale..

[link=http://www.rcgroups.com/forums/showthread.php?t=1833053]Midwest Sniffer kit[/link]

ffkiwi

I feel the Sniffer-at 31" or thereabouts is a bit small for the MP Jet. I scratch built one for for one of the PAL K&B Infant replicas some years back, and that had ample power to fly it. My previous post suggested the 'Super Sniffer'-which is something around 40-odd inch span as a good match for the Classic-assuming that you want to do relaxed laid back flying-and these engines, while easy handling, quiet and turning big props are not all that powerful-so that's exactly the sort of use they're meant for.
Between the various plans services, ebay vendors, kit manufacturers, and internet sites like outerzone and hippocketaeronautics, there should be any number of suitable models available either as kits or plans-not to mention what some of the UK magazines like AMI, RCM&E, Model Flyer offer by way of free full size pull out centrefold plans- back issues of most of these are available either from the various publishers or from the bigger model magazine back issue vendors.

ChrisM
'ffkiwi'

MJD

My Feedback: (1)

Yeah you're tight - I forgot the Sniffer was the little one. I should know, I built one in the '80's. Think I used a Testors or Wen Mac .049, idea being to keep the power moderate with a wheezy engine, but as I recall it was still pretty sprightly.

ffkiwi

I did a quick google search for Super Sniffer plans and came up with several sources plus numerous references on threads here and on RC Groups-the gist of at least some is that the Buzzard B is a better flying model than the Super S........though I had no issues with the standard one as a FF. Interestingly I've seen the span of that one quoted as being variously 29", 30" and 31"-perhaps some distortion has crept in over the years...I was also a bit out with the size-it appears to be 48" span-that's probably getting on the large size for the MP Jet Classic 040-unless built very very light................

ChrisM
'ffkiwi'

Wagon1

I built a Spirit of Yesteryear Buzzard Bombshell a few years ago. I used a TT .07 and had some difficulty (I have a pic somewhere I'll try to find). I'm sure it was a build/cg issue, but it never flew right. Also, the fit is VERY tight for any electronics/guts. I have the .07 on a Kadito now. I flew a Super Sniffer as a kid .As a matter of fact, I think it is still flying around somewhere. It went out of sight after a few flights. I bought a set of SS plans on Ebay and hope to build it someday. No wing ribs on the plans so I'll have to just take a whack at them....

xanaphyst

My Feedback: (17)

Success with the cloud ranger. Finally put in the test flight after waiting for wind to die off. The MP Jet didn't quite have the pull I was expecting but not quite sure if it is me or the engine yet. It ran great just not quite
the power I hoped for.

On another note I ran 3 .10 engines today, 2 FP's and 1 LA. I ran the same prop on all of them and the performance was exactly the same on all 3 (14,500 on a 7x4 APC). That answers my question about if the FP's were stronger. The LA was a little
lighter than the FP's so I guess I'll stick to the LA's in the future.

Hoping to get the DNU flown soon..maybe tomorrow.

ffkiwi

The MP Jet Classic 040s are not powerful engines-they only produce about 0.03-.04 BHP. For max power you'd want to use a 7x4 (pref nylon as I've suggested before)-for ease of handling, an 8x4. (7-8000 on a 7x4, 5-6000 on an 8x4-depending on the prop, and your settings) You certainly don't want to go down to typical 1/2A glow engine prop sizes such as 6x3 or 5x3-if you do you'll discover that diesels BITE! ....and the revs you'd get would be quite disappointing. These sideports (MP Jet, Letmo, Mills 75, Amco 87) all normally peak at around about 7-8000 rpm or so (in that respect they're much like the early ignition engines of the 30s and 40s) so there is no point in propping them to rev higher-all that happens is they get snappy, don't run very happily-and produce less thrust!
They're at their best flying lightly loaded vintage or vintage style models just cruising around or equally at home in FF scale models turning a big scale size prop. If you want hot dogging style 1/2A performance then you need their big brothers-the MP Jet 061s............
The .10FP and .10LA prop rpm figures you state tend to support the idea that there is really no performance difference between the FP and LA series (though I think the earlier 10FSR had a little more poke) IIRC OS made some porting changes with the FPs compared with earlier FSR models (and not just in the 10 displacement)-of course a lot would depend on what 7x3 prop-and what fuel..........of course it could be simply that you happened to chance on a load where both engines BHP power curves happened to intersect-so the revs on that prop coincided....

ChrisM
'ffkiwi'


[A quick afterthought-if you want to explore the more powerful diesel options in 1/2A-then there are also the PAW diesels-which all come with R/C throttle options in the 1/2A sizes of .03, .049 and .06-even the 03 produces close to double (0.07BHP at 12,500 rpm) the power of the MP Jet Classic-but you sacrifice some of the pleasant handling of the MP Jet in the process. Personally I'd still rate the MP Jet 061s as better made engines than the PAWs-not that there's a lot to criticise about the PAWs]

xanaphyst

My Feedback: (17)

DNU FLIGHT REPORT - Now I see why everyone likes this plane. Great performer on the cheap production engine. The 5x3 prop seemed right for the job but I did not try anything else to compare.



FFKiwi....I may be a bit confusing about the MP Jet stuff....the ranger uses the MP Jet 061 power. I have not tried the 040 classic on anything yet. I've run all latest hobby stuff on this one thread like a blog. I do love that little engine
and need to get it on something. I picked up a freeflight model for it that will be RC assist but have not started it yet. It's a 33" 1/2a ZEEK with 176 sq/in of wing. I'm hoping to start on it after getting a Wunder together which I started today.

ffkiwi

Sorry-I assumed that since you were earlier talking about the MP Jet Classic 0.6 then this was what you had used in the Cloudranger you didn't specifically mention that it was the 061...in complete contrast to what I said above regarding the Classic, the 061 MP Jets are powerful engines for their size-in both diesel and glow versions so I'm at a bit of a loss to rationalise your reported 'didn't have quite the pull'-....compared to what exactly? Certainly they would comprehensively out pull a TD-but not a Cyclon, Profi or Fora. bear in mind though that they are fairly high timed-even the diesel-and need to rev to produce their output-even the diesel one peaks 0.21BHP- at around 17,000rpm (meaning nothing bigger than a 7x3 if you want to utilise that output)-you can hang an 8x4 on it -but that will hold it down to just over 10,000rpm and about half its possible power. The glow will give you a bit more [0.25BHP @ 27,000 (25%nitro, open exhaust)] largely by dint of revving higher....mind you you have to go down to a 5x2 to get those revs-a bit fine for R/C use! On normal 1/2A sized R/C props (6x4, 6x3) either will give you screeds of power-with the diesel version probably have a slight edge with those loads.........

ChrisM
'ffkiwi'

PS the rpms and power quoted come directly from the published 'Aeromodeller' engine tests-Apr 1994 (061D) and Aug 1994 (061G) respectively. There was an additional test done on the factory F1J Special 061 glow (June 1996)-but since that wasn't an R/C engine I haven't touched on it here

xanaphyst

My Feedback: (17)

Do you know about what RPM's I should see on the 061 with a 6x3 and 6x4 ??? I tried a 6x3.5 today but did not fly or tach it as it took a chunk out my finger while trying to fine tune the needle.
I've read reports of 17K on a 7x3. Does this sound right to you? I'm starting to wonder if my fuel may be a problem.

exocet-RCU

My Feedback: (1)

Looking for the DNU plans/kit. Searched through the 1/2A forum and found a link to PTUlmers website that didn't work and plans for the low wing version. Can anyone direct me to the high wing version plans or kit?

Thanks

Tim

xanaphyst

My Feedback: (17)

sure exocet...here it is (if this works). I had a lot of fun building it and even more fun flying it. A cheapo cox production engine flies it great. I bet a norvel or TeeDee would be a hot ticket for this one.

ffkiwi

That'll learn you!................give me a day or two and I'll generate some figures. Actually 17,000 on a 7x3 sounds bang on-the aforementioned AM engine test gives 16,800rpm (open exhaust) and 16,600rpm (with muffler) for an APC 7x3-I'd imagine even more with the Master 7x3 which is a lighter load. On a Kavan 6x4 they quote 16,700 and 16900 respectively. While there are props and props, I'd consider a 6x4 and a 7x3 to be equivalent loads-and these figures bear that out. Fuel was Model Technics D3000-which is their twin BB engine racing mix...........and (because someone is bound to ask!) is:
47.5% kero, 30% ether, 20% castor and 2.5% IPN They didn't test it on a 6x3-but on an APC 5.7x3 they got 21,400 and 21,500......I imagine on a typical 6x3 you'd see something in the 18,000-19,000 range....

ChrisM
'ffkiwi'

Note that these rpm figures are all off the standard 061D BB engine, not the R/C carb equipped one...........