AMB

OK Group finally hit the local hobby shop to pick up bits and pieces or hardware and a few props. They had a really nice chipmonk built up ARF ( not foam)
for a 400 size electric motor, wingspan is only 38 inchs wonder if big enough for the 061MP jet it would be hot in the air martin

ffkiwi

Isn't that what a throttle is for?......................

ChrisM
'ffkiwi'

PS-on second thoughts-foam and diesel fuel?.............when I was a kid I used to dissolve bits of polystyrene with kerosene. Of course it might not be made from polystyrene foam...........

fiery

My Feedback: (2)

I think Martin means balsa, light ply and shrink film Chris.

If the weight up front of the MP Jet 061 and silencer is equivalent to the weight of the specified electric motor, I'd say go for it.

AMB

It is built up shrink covering, just grabbed a quick look was on time schedule, nice access, hatch on bottom easy tank and battery install, just chop off electric mount
add an other firewall 1/8th ply, bolt up mount, thats about it , done this a few times before, but 09s and up martin
most of my electric to diesel only plus or minus 1 oz over stated weight on the box, the first were lighter those big nicad packs for electric motors were heavy had to add nose weight to balance

ffkiwi

sorry Martin-guilty of a quick glance at your first post then leaping into print........! [speed reading will be the death of me.......!] Now that we've eliminated it as being a foam model, I'd say go right ahead. You could probably get away with a 1oz tank-or even a film canister one to limit excess weight......
......which starts me thinking-one of the things that adds both bulk and weight is the muffler-(admittedly only about half an ounce!)-I wonder of MP Jet could be persuaded to produce a lightweight 'tongue' muffler like a lot of the C/L fliers use....................
[I suppose you could use the same argument for the TT07-perhaps what is needed is a 'generic' 06-074 size, with an engine specific mounting adaptor...........]

ChrisM
'ffkiwi'

Mr Cox

No problem, just keep it light. I have one with a Norvel .074 in it, it ended up about 2oz lighter than the electric version and it flies at half throttle...

[youtube]http://www.youtube.com/watch?v=trSCx-6zlAo[/youtube]

AMB

Mr Cox looks good looks like we will pick it up for the next one did not notice brand , but everything well done martin

AMB

Just messed around with the engine MPJet 061, took it out of box mounted 7x4 wood prop , hand holding and a little Davis 1/2A fuel flipped , first 3 or 4 flips fired with kickback, 4th roared off on the prime will mount on stand and break in / turning slowly tight pinch, flipping not evident and has that nice bounce martin

steve111

The mufflers aren't all that heavy - from memory the whole engine (CL) + muffler is only 88g. It will want a good break-in - the instructions suggest 40% castor, and from experience that's what I'd go with, even if it seems like a lot for a TBR engine. Expect about the same performance as a Norvel 074 glow. Mine does about 17600 with an APC 7x3, unwinding to 20000 in the air [>:] . Quite a bit more power and thrust than a traditional sport 09 glow (eg Enya 09 or OS 10FSR). Enjoy!

ffkiwi

Actually-no-the only published engine test on the 061D rates it at ~0.21HP, only about three quarters of what the Enya 09 and OS 10 FSR produce-also by test! If you were referring to the 061 GLOW, then you'd be correct.........

ChrisM
'ffkiwi'

steve111

No, I'm not referring to the glow, I'm referring to what I've actually observed running the diesel for the last 18 months. I've also got the glow, and so far it isn't as strong as the diesel (though to be fair it's only barely run-in).

qazimoto

My Feedback: (1)

Mmm,

if you'd used Petrol instead of Kero you could have made a good replacement for Nap*lm.

Mr Cox

I don't know where you are getting your numbers from, but a 7x3 spinning at 17500rpm would be about 0.20HP and similar to the test you are referring too. An Enya 09 and the OS .10FSR will make around 0.16-17HP on a 7x4, in my experience, with muffler and RC carb (at 10% Nitro).

ffkiwi

I am quoting from proper published engine tests on all three engines-not rpm figures, which are meaningless in isolation. Check Aeromodeller-and Model Airplane News if you want to view the published tests.. Prop-rpm figures are meaningless except for motor to motor comparison using the same prop. Prop torque coefficients vary widely, let alone prop blade area, pitch, etc. A '7x4' is merely a description, without the additional data to relate it to power absorption.

ChrisM
'ffkiwi'

ffkiwi

Well for a start you can't do a side by side comparison-you have to prop the glow appropriately for its peak power band-which is about 25,000rpm (and higher-27,000- still for the F1J Special variant)-considerably higher than the diesel which tops out by about 21,000. Of course the diesel will out-turn the glow lower down on bigger props. A 7x3 is about optimum for the 061 diesel which peaks at around 17,000

ChrisM
'ffkiwi'

steve111

Chris, I think it goes without saying that you'd prop them appropriately. Thing is, the current 061 glow has a recommended rev range of 14000-20000, and suggested prop range of 6-3 to 7-3. Recommended break-in prop is 7x3.5. Not at all the Norvel-type screamer I would've expected, and perhaps the specs have changed since they were last in production. I'm sure you could still stick a tiny prop on it and have it doing 25000+, but it goes against the maker's recommendations, and 17000 with a 7x3 is more use to me in the real world anyway.

Steve

ffkiwi

Fair enough Steve! Though-sometimes I wonder just how far some manufacturers actually take their products. The MP Jet 061 is quite a sleeper-and capable of much greater output than its manufacturers seem prepared to admit-largely I suspect because it is very well-and very strongly-built. [Possibly because it was designed as a diesel rather than a glow?] I do know that Doug Galbreath-the US F1C flier and engine expert was so impressed with their potential that he conducted extensive modifications to the point where they would equal an AD06 (which prior to the advent of the Cyclon was the yardstick by which F1J engine performance was measured-I have two of these variants) and before MP Jet themselves developed their own 'F1J Special' which was not as powerful.
It would seem-and you see it in some power curves from the more astute testers, that some engines have a 'stepwise' hump style of power output-with several distinct BHP maxima not the traditional smooth curve we are generally familiar with. The MP Jet seems to be one-and the ASP 12 another-with a much higher performance potential accessible only if you prop it down significantly. [For example the MP Jet F1J Special needed to go down to a Graupner 5x2 to develop its top output-on 'normal' sized props it was potent-but not spectacular.........]

ChrisM
'ffkiwi'

steve111

I dare say you're right, Chris. Given how well they're made, I can't see any reason why they shouldn't be structurally capable of much higher rpm. (My MP Jets certainly feel like they'll last much longer than my Norvels.) Still, I use them for little CL stunters, so am happy to have something capable of swinging a bigger prop.

Mr Cox

It sounds like you are comparing the maximum ever possible HP from the Enya, i.e. it can produce about 0.24HP but that is without muffler, fitted with a fixed Cl venturi and running 30% nitro. It can then develop .24HP at 18000rpm (from the test of the Enya III by Peter Chinn). This is far from regular usage though. So comparing an MP Jet D on a typical prop (7x3) with the Enya 09 on its typical setup (7x4 prop, 10% nitro, RC carb and muffler) giving 0.16HP (according to the test by Peter Chinn). The MP jet will thereby match the power output of the Enya engine on their typical set-ups that can be used for flying rather than just bench running...

steve111

That's pretty much where I was coming from. Typically I'll use an Enya 09-IV with a 7x4 MA GF3, CL venturi and 10% nitro. This peaks at about 15200. My MP Jet 061 diesel uses an APC 7x3 and CL venturi, and peaks at about 17600 (fuel is 30% Benol, 35% ether, 2% DII).

That gives .19 bhp and 1.58 lb static thrust for the Enya, versus .25 bhp and 1.87 lb static thrust for the MP Jet. Quite an eye-opener...

DeviousDave

The low end on these Mp Jet .061D's seems to be about 5-5, which they will turn in the 20-21k range. Very useful....[>:]

gcb

If your plane flys the way you want it to, who cares if the engine has more or less powerful than an engine you don't have in your plane?

George

AMB

George well put, but stats helpful adds to our knowledge base regards martin

the chipmunk looks good when we get it and set up will start with the the 7x3 and 7x4 no need to run this at `16K or more plus (MPJET 061D)

Looks Mr Cox called it

ffkiwi

Because if you don't know how much power the engine produces, nor the shape of the power curve,and where it sits, you have no idea of what is an appropriate prop to use on it-except by comparison with another of similar size-and that's guesswork. Personally I consider there's no place for guesswork on my models.............

ChrisM
'ffkiwi'

Mr Cox

I really like the chipmunk, it just looks and flies great, and is small enough to fit in the car with the wing on. In fact I haven't had the wing off in the last two years...

If anyone is interested in more details of the installation, I've made a little "conversion" thread on the 1/2a forum; [link=http://www.rcuniverse.com/forum/m_9052204/anchors_9052204/mpage_1/key_/anchor/tm.htm#9052204]Glow conversion[/link]

It sports a Norvel .074, inverted, fully cowled, and has a built in starter spring.