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I’m So Weak …

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Re: I’m So Weak …

Post  batjac on Wed Aug 17, 2016 9:55 pm

Oldenginerod wrote:
batjac wrote:
Oldenginerod wrote:The best way to get it off is to remove the piston/rod assembly and drive the crankshaft out.  The clutch can't be dismantled to repair it if it gets damaged.  When you refit the plate, ensure you align the two flats of the centre spring anchor with the corresponding apeture in the centre of the clutch.  Otherwise, the whole thing will jam up solid.

Rod.

Rod, can the whole spring assembly be removed and left off?  I don't know how you'd have a drive plate for the prop to seat against if the housing was removed.  Can just the rear spring assembly be taken off and the drive plate be put back on?

The Inquisitive Mark
Yes, I think the spring housing is riveted to the crankcase, or possibly retained by a clip.  I will need to have a look in my parts bin.
The clutch assembly is the prop driver, which can be reinstalled once the spring & housing is removed.  I think the crankshaft is dimensionally similar to the earlier WenMacs, so it may be possible to use a prop driver off an earlier model (Mk2 or Mk3 maybe).

I guess I may end up doing this sooner than I planned.  I was trying out my new tweaked needle valve on my pipe bomb engine prior to mounting the engine in the plane, and during one run, the starter spring broke.  It’s strange that the spring broke during the engine run, rather than during the starting wind up as I’d have thought it would.  So, I may take the starter assembly off and remove the extra weight.  Maybe I’ll get more RPMs that way.

The tweaked needle did no good.  It was the same or worse than the first needle.  I ended up doing the thing that I was hoping to avoid.   I put in a new glow head.  On a Cox it would be no big deal.  But I only had five new Testors glow heads left.  Now down to four.  Not easy things to find these days at a reasonable price.  But the engine runs a little more reliably now.  The previous head’s filament would glow okay, but the filament wire was kind smashed together.  One of the other flyers at the filed today told me he had the proper taps and fixtures to convert the Testors head to use Nelson plugs.  Maybe I’ll bring him the just removed plug and let him play with it.  He’s got a good CNC outfit that he uses to make venturis and tongue mufflers and things for the local C/L guys.

Well, the paint should be dry on the BTC-3, so I guess I’ll go put it all together.  Maybe I’ll be able to get out to test fly it tomorrow.

The Hopeful Mark
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Re: I’m So Weak …

Post  Dane Martin on Thu Aug 18, 2016 10:09 am

Mark,
I recently acquired a very nice pipe bomb engine. May I copy your plane? I was wondering what to do with it!
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Re: I’m So Weak …

Post  batjac on Thu Aug 18, 2016 2:02 pm

Dane Martin wrote:Mark,
I recently acquired a very nice pipe bomb engine. May I copy your plane? I was wondering what to do with it!

Dane, that's why I put the drawing up for Y'all. But I made a couple of changes to fit the engine with a spring starter. I was originally going to use a case with the geared face for those plastic handled zip starters. I'll re-draw the plan and upload that if you want to cook book it. Otherwise, take what I already have up and tweak it to your heart's content.

The Magnanimous Mark
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Re: I’m So Weak …

Post  batjac on Thu Aug 18, 2016 2:07 pm

Well, too much to do today to go flying, so I’ll just upload the assembled plane photos.







The Busy Mark
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Re: I’m So Weak …

Post  RknRusty on Thu Aug 18, 2016 6:20 pm

That's a Damn good looking plane. It appears to be very well built, I hope the Pipe Bomb does it justice.
Rusty

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Re: I’m So Weak …

Post  NEW222 on Thu Aug 18, 2016 8:02 pm

Dang, that thing looks sharp!
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Re: I’m So Weak …

Post  Cribbs74 on Thu Aug 18, 2016 8:43 pm

Good job on the engine mount.
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Re: I’m So Weak …

Post  Oldenginerod on Fri Aug 19, 2016 7:59 am

I'm just impressed that someone has gone to the effort to make use of something that would otherwise be discarded. I have little doubt the engine will do the job.
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Re: I’m So Weak …

Post  Dane Martin on Fri Aug 19, 2016 8:32 am

batjac wrote:
Dane Martin wrote:Mark,
I recently acquired a very nice pipe bomb engine. May I copy your plane? I was wondering what to do with it!

Dane, that's why I put the drawing up for Y'all.  But I made a couple of changes to fit the engine with a spring starter.  I was originally going to use a case with the geared face for those plastic handled zip starters.  I'll re-draw the plan and upload that if you want to cook book it.  Otherwise, take what I already have up and tweak it to your heart's content.

The Magnanimous Mark

Also,  I noticed your engine does not have the fuel tank on the back. I have never seen one of these things, do I just give the tank a good tug and pull it off?

Thanks!

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Re: I’m So Weak …

Post  batjac on Fri Aug 19, 2016 9:06 am

Dane,  here is the thread on how I converted a standard pipe bomb engine:

Testor's Conversion

The 70's Mark
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Re: I’m So Weak …

Post  Marleysky on Fri Aug 19, 2016 9:11 am

Dane, IF you want or need to remove the tank, follow the example in this thread:
https://www.coxengineforum.com/t10050-testors-pipe-bomb-engine-won-t-run#127239
Otherwise you may build your plane with a mount designed for a Baby Bee, rather than ruin a pipe bomb!! I think that what you have is the "8000" series engine, which is the pipe bomb with tank with mounting holes that match*** the baby bee. Should bee a good running engine as is.

***not an exact match, but is four holes in a firewall.


Last edited by Marleysky on Fri Aug 19, 2016 9:15 am; edited 1 time in total (Reason for editing : Correction on mount)
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Re: I’m So Weak …

Post  Dane Martin on Fri Aug 19, 2016 9:42 am

Marleysky wrote:Dane, IF you want or need to remove the tank, follow the example in this thread:
https://www.coxengineforum.com/t10050-testors-pipe-bomb-engine-won-t-run#127239
Otherwise you may build your plane with a mount designed for a Baby Bee, rather than ruin a pipe bomb!! I think that what you have is the "8000" series engine, which is the pipe bomb with tank with mounting holes that match*** the baby bee. Should bee a good running engine as is.

***not an exact match, but is four holes in a firewall.

Oh!!! Wow. I'm really dumb! Lol. I have mounting holes on my fuel tank. Oh, and my engine already runs great. Ok then, 1/2A Skyray it is.

Thanks though mark. I'm still using your ideas with the sig air foil slab wings.
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Re: I’m So Weak …

Post  roddie on Fri Aug 19, 2016 10:28 am

Dane Martin wrote:

Also,  I noticed your engine does not have the fuel tank on the back. I have never seen one of these things, do I just give the tank a good tug and pull it off?

Thanks!


Dean, I would say "yes".. My engine is exactly the same, other than the tank. I'd pull it straight-back though... to avoid breaking-off the tank's "tab" that fits into the right side of the case. You'll have to ask others if that tank can be modified (cut/sawn) to use only the reed-holder like Mark did. If the answer is yes; then the tab could be filed-down/cut-off so that the rear-end can be rotated to a NVA position to suit the mount that you build.

Mark, First off.. Awesome, smart-looking little model!!! Just a thought... those six screws holding the ply-plate on could be substituted with "nylon" machine-screws. May sound crazy.. but you could save some significant weight.

Here's an example of the difference in weight of x1 steel #8 x 1.5" screw vs. x2 nylon ones in grams.




Granted... you're not using #8 wood screws... but the weight difference between the two materials translates the same. Nylon screws can be found in 4-40 size.. in an assortment of lengths.. or just cut longer ones to the length required. They'd likely hold adequately for this application possibly without needing to tap the holes, depending on the size screws you have in there now. Correct size pilot-holes would probably allow nylon screws to self-tap their way in.


Last edited by roddie on Fri Aug 19, 2016 11:50 am; edited 1 time in total (Reason for editing : self-tap note)
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Re: I’m So Weak …

Post  RknRusty on Fri Aug 19, 2016 11:53 am

Dane Martin wrote:...Thanks though mark. I'm still using your ideas with the sig air foil slab wings.

Glue two of those airfoils back to back for a 1/2" symmetrical airfoil.

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Re: I’m So Weak …

Post  Dane Martin on Fri Aug 19, 2016 5:47 pm

RknRusty wrote:
Dane Martin wrote:...Thanks though mark. I'm still using your ideas with the sig air foil slab wings.

Glue two of those airfoils back to back for a 1/2" symmetrical airfoil.

Look at you. Clever as you are handsome!
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Re: I’m So Weak …

Post  Oldenginerod on Fri Aug 19, 2016 5:56 pm

Dane Martin wrote:
batjac wrote:
Dane Martin wrote:Mark,
I recently acquired a very nice pipe bomb engine. May I copy your plane? I was wondering what to do with it!

Dane, that's why I put the drawing up for Y'all.  But I made a couple of changes to fit the engine with a spring starter.  I was originally going to use a case with the geared face for those plastic handled zip starters.  I'll re-draw the plan and upload that if you want to cook book it.  Otherwise, take what I already have up and tweak it to your heart's content.

The Magnanimous Mark

Also,  I noticed your engine does not have the fuel tank on the back. I have never seen one of these things, do I just give the tank a good tug and pull it off?

Thanks!


You have an 8000 series engine so I wouldn't mess with it.  Bolt it on, fill the tank & fly it.  If you don't want to use the integral tank, please don't destroy it.  You can get an old Fly'em style tank & cut that down, or maybe the rear ends that Bernie is selling will fit.
http://www.ebay.com/itm/Testors-049-Pipe-Bomb-Model-Engine-Venturi-Reed-Needle-Valve-Spring-049-NOS-/222213415713?hash=item33bcf3a321:g:URUAAOSwtnpXjotT  
My 8000 engines have a small tapered pin on the front of the tank which allows you to twist the tank & it pops off, but be careful.  Your engine looks like it has a straight pin in between the rails, so careful not to break it.
When you mount the 8000 the cylinder will be to the side.  I can't recall whether it's inside or outside of the circle.  The pin on the tank is to locate the cylinder in the correct orientation and prevent the engine from twisting in use.

Rod.
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Re: I’m So Weak …

Post  RknRusty on Fri Aug 19, 2016 5:57 pm

Dane Martin wrote:
RknRusty wrote:
Dane Martin wrote:...Thanks though mark. I'm still using your ideas with the sig air foil slab wings.

Glue two of those airfoils back to back for a 1/2" symmetrical airfoil.

Look at you. Clever as you are handsome!
lol! highly questionable, Lol.

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Re: I’m So Weak …

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