"Micromaster"-- Centerline twin using small industrial engines

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blane.c

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When I look at the engine crankshaft from the pulley side I see a small protrusion of greater diameter extending from the crankcase seal.

B&S 810 CRANKSHAFT END CLOSEUP.PNG B&S 810 CRANKSHAFT LONG.PNG

You can see the groove towards the end of the crankshaft on the left hand end in the second image. This groove is approximately were the oil seal is. I would investigate the idea of a "beefy cup" area of a propeller extension that would be a press fit over that protrusion and not interfere with the seal. From an engineering standpoint would it be sufficient in transferring the stresses to the bigger diameter or just a decoration?
 

Vigilant1

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You know what would really lend itself to becoming a centreline twin? Fritz' Ranger.
Just between you and I, the speed with which Fritz is pushing that project ahead is borderline alarming. Why, in the time we've been yacking about this one issue (engines), Fritz has built the CAD files for a complete fuselage, made a mock up, and has a couple of groupies already cutting materials. No--the Micromaster will NOT be rushed to first flight in this way! ;)
 

Vigilant1

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Any progress update's on the Micromaster?
No, nothing significant. Little things:
- I have written a letter to Mel Asberry (he writes the "Ask the DAR" column in Kitplanes) about the Operating Limitations of a plane like the Micromaster--and how a designer/bulder of such a plane can know if he'll be allowed to fly it without thousands of dollars worth of additional and ongoing instruction.

I wrote:
I am working on a single-seat original design with a two-engine, centerline thrust configuration (tractor in front, pusher in back, like the configuration of a Cessna 337). As I understand things, FAR 61.31 (L) (2) ( B ) exempts single-seat experimental aircraft from category and class requirements, but the DAR who conducts the airworthiness inspection may require the pilot to have the appropriate category and class pilot certificate and can document these in the Operating Limitations.

As a practical matter, what factors would a DAR consider when deciding whether to require a MEL rating for a plane like this? The design is intended to be able maintain altitude and climb on a single engine and to have a Vmc that is less than Vs0, so engine-out handling will be very similar to the handling of a single engine aircraft. As the cost for the instruction to gain the MEL rating would likely make this project impractical, I'd like to know before spending a lot of resources on this project if the DAR who issues the airworthiness certificate for the plane is likely to list a MEL rating as a requirement in the Operating Limitations for such an aircraft.
The MicroMaster project becomes a lot less appealing to me if I have to spend $5K to get an MEL, and stay current (rent a twin for every BFR?) just to buzz around in this little plane. Anyway, we'll see if Mr Asberry thinks the question is worthy of attention. His column in Kitplanes is well written and useful, but this is a question that is a bit off the beaten path.

- I struggled a bit with some drawings. I probably need to get some help to identify software that is worth learning. I wasted a lot of time, I dang sure am no Fritz. I coud have gotten better results with graph paper and a ruler. Nothing worth sharing.

- The several tables already in this thread (with estimated specs and performance estimates of various versions) have been de-formatted into oblivion by the transition to the new Xenforo forum software. I'm trying to find a way to make future tables that is at least as easy as what we used to have in the old software.

- I'm following the ongoing thread on Vanguard/B&S aero engine conversion. As you noted previously, the Micromaster would be a pretty good mule for putting flying hours on these engines, provided it can fly (and climb) well on one of them. Every hour of flight time puts two hours on the engines, and we'd get to wring out both a tractor and a pusher configuration at the same time. Unless something changes from previous estimates, the MicroMaster would need at least 28 HP for safe single-engine climb. So, I'm focused on the Vanguard 810cc engine now because, as these industrial engines go:
-- It has a good HP-per-dollar ratio.
-- It has a good HP-per-pound ratio
-- Folks are already flying them successfully in direct drive mode. There's even a kit supplier that is supporting them with conversion parts. So, apparently it can work.

Any other updates from interested parties?
 
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BBerson

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I think a multi engine solo endorsement is an option, instead of the rating.
See the Operating Limitations for solo endorsements.
 

pictsidhe

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When I look at the engine crankshaft from the pulley side I see a small protrusion of greater diameter extending from the crankcase seal.

View attachment 83747 View attachment 83748

You can see the groove towards the end of the crankshaft on the left hand end in the second image. This groove is approximately were the oil seal is. I would investigate the idea of a "beefy cup" area of a propeller extension that would be a press fit over that protrusion and not interfere with the seal. From an engineering standpoint would it be sufficient in transferring the stresses to the bigger diameter or just a decoration?
Decoration. Look for tapered the shaft version. That will also sort out the needed fit with the prop adaptor.

Edit, crank drawings for the small block vanguard as I couldn't find one for the 810. Those are standard crank ends. At least one of tapers on the first page is also available on the 810s as well as some others. The rest of the crank is different, though.
 
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TFF

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Once you have a multi, you do not have to “stay current” to fly yourself and it only takes three takeoffs and landings in your own plane to be legal to carry people every 90 days. Biannual does not have to be in anything special.
 

Vigilant1

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I think a multi engine solo endorsement is an option, instead of the rating.
See the Operating Limitations for solo endorsements.
It's hard for me to tell. The boilerplate language often used for the Operating Limitations these days says:
"The pilot in command of this aircraft must hold a pilot certificate or an authorized instructor's logbook endorsement.
Well, anyone with a PPC/SEL meets that requirement.
And the next line of boilerplate reads"
The pilot in command must meet the requirements of § 61.31(e), (f), (g), (h), (i), and (j) as appropriate.
Section 61.31 is all about type rating requirements, additional training, and authorization requirements. (e) is for complex airplanes, (f) is for high performance airplanes, (g) is pressurized airplanes, (h) is "additional type-specific training, (i) is tailwheel acft, and (j) is gliders. At the end of that section we have this which would seem to exclude E-AB aircraft from the requirements of § 61.31 (since they aren't type-certified):
(l)(1) This section does not require a category and class rating for aircraft not type-certified as airplanes, rotorcraft . . .
And to make it more clear:
(2)the rating limitations of this section do not apply to: . . .(iii) the holder of a pilot certificate when operating an aircraft under the authority of -- (B) an experimental certificate, unless the operation involves carrying a passenger.
But, I'm pretty sure the DAR has quite a bit of discretion with regard to what is written in the OL's, and whoever operates the plane obviously has to follow those. I would imagine the natural inclination would be for the DAR to stipulate in the OL that any operator of this multiengine E-AB must have a multiengine rating or endorsement (to include multiengine, centerline thrust). But, I would think a DAR might also use this discretion to >not< require such a rating/endorsement, given the particular aircraft's attributes:
--- Single seat
--- Centerline thrust
--- Safe single-engine climb at the MTOW listed on the OLs (maybe include a max density altitude?--seems unwarranted as even above this altitude the plane would be safer if one engine is lost than a single would be in a similar occurrence. Maybe stipulate "no single engine takeoffs" just as the FAA eventually required Cessna to do for the 336/337. This is one of those things you'd think you wouldn't need to tell an adult, much less a pilot, but apparently . . .)

Once you have a multi, you do not have to “stay current” to fly yourself and it only takes three takeoffs and landings in your own plane to be legal to carry people every 90 days. Biannual does not have to be in anything special.
Thanks, good to know. Still, that up-front cost to get the rating, or even an endorsement, might cost more than this little mower-powered sky scooter.
 
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blane.c

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How are you doing on endorsements? Most twins are high performance needs endorsement, most twins are complex needs endorsement, sometimes less expensive to take endorsement rides in a high performance complex single then multi ride is just for multi. Also Sierra Seaplanes " I think" has a regular land Apache that may be reasonable. Remember you just want a VFR rating? Most packages are for commercial pilots so include MEL instrument training for checkride. Doing engine out instrument approaches really ramps up the time for many.
 

Vigilant1

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How are you doing on endorsements?
How am I doing on endorsements? I'm doing great! The last one I got was for solo flight when I was a student, and that's the only one I need or want. My hope is that a plane like the Micromaster wouldn't require any endorsements or additional ratings, but we'll see about that. It's not high performance, it's not complex, it's single seat, it is experimental, and without a relevant Vmc or any need for fancy footwork or throttle adjustments to keep it upright in the event of an engine failure, the design is intended to avoid many of the peculiar vices of conventional twins--and singles.

Another issue might be insurance. While hull insurance might not be a major concern for many folks on a low-cost, moderate-value homebuilt, lots of airports require any actively flown plane in one of their hangars or tiedowns to be covered by liability insurance. And, I'm guessing those insurers might require a multiengine rating or endorsement even inf the FAA doesn't.

I think the Cri-Cri folks have covered some of this ground already. There aren't many in the US, and they aren't a true centerline thrust twin, but they are experimental, single seat, and the engine/slipstream/canopy geometry reportedly makes them fairly easy to handle one one engine.
 
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blane.c

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I wonder about waiver or letter of authorization/or/deviation/or/demonstrated ability. You need special permission. It may be how Cri-Cri owners do it or they may of all had to go get a rating. Some of them may have satisfactorily demonstrated the ability to control the aircraft to the FAA or authorized inspector and have gotten some form of letter. A demonstration of ability can be witnessed from an inspector on the ground in communication with the pilot. A insurance company that routinely insures aircraft and pilots will likely recognize a letter from the FAA.
 

Vigilant1

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I wonder about waiver or letter of authorization/or/deviation/or/demonstrated ability. You need special permission. It may be how Cri-Cri owners do it or they may of all had to go get a rating. Some of them may have satisfactorily demonstrated the ability to control the aircraft to the FAA or authorized inspector and have gotten some form of letter. A demonstration of ability can be witnessed from an inspector on the ground in communication with the pilot. A insurance company that routinely insures aircraft and pilots will likely recognize a letter from the FAA.
That's another avenue worth looking into, thanks. If the "permission" is included in the aircraft operating limitations (i.e. if they contain no stated requirement for a multiengine rating or endorsement), that would mean the permission is linked to the plane, not the pilot, and that would be most convenient down the road.
If the LoA, deviation, demonstrated ability, etc is granted to the pilot (not the plane), then it's a bit more cumbersome later (but might still be a lot cheaper and just as conservative/safe as getting a MEL rating for this purpose.) For example, maybe the attributes of the plane could be documented for the FAA, then during the flight portion the FAA inspector could see the plane/pilot demonstrate a simulated engine failure on climbout (demonstrate it can be done on either engine), a single-engine go-around with reconfiguration, etc. Ideally it would be as simple as that, and ideally there's already a well established procedure for it (applicable to E-AB single seat acft), and the permission to operate is tied to the aircraft (with properly placarded procedures in the airplane/checklist) . I'm pretty sure it will be more involved than this ideal scenario.
 

BBerson

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But why do you want a rating? The purpose of a rating is to have the privilege of carrying a passenger.
To fly solo doesn't require a rating.
The FAA requires a LOA for jets, I think. I haven't heard what is required for a CriCri, if anything.
 

Vigilant1

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But why do you want a rating? The purpose of a rating is to have the privilege of carrying a passenger.
To fly solo doesn't require a rating.
The FAA requires a LOA for jets, I think. I haven't heard what is required for a CriCri, if anything.
Agreed, I don't want to get an MEL rating or an endorsement in order to fly a plane like the Micromaster (assuming it performs as we'd like: safe single-engine ROC on either engine, demonstrated min controllable airspeed < stall speed, etc). But (as I understand things) when writing the Operating Limitations, the DAR has significant discretion, and one "safe" thing to do is to require that anyone operating this multiengine plane have a multiengine rating or endorsement.

Here's a question to the EAA and their answer, FWIW. It is about the Cri-Cri, but seems applicable:
Q & A: I have been giving serious thought to building a Cri-Cri. But how does the FAA view this airplane? It is light enough to be an ultralight, but appears to fly too fast to be one. It can't qualify as an LSA because it has two engines. Therefore it must be an experimental amateur-built twin, requiring at least a private certificate with a multi-engine rating and a third class medical to fly it, right?

Answer: You are correct in that the Cri-Cri does not qualify as a Part 103 ultralight or a light-sport aircraft. While it does have two engines, there is a provision in FAR 61.31 that allows an experimental aircraft to be exempt from category and class requirements:

Type rating requirements, additional training, and authorization requirements.

(L) Exceptions.
(2) The rating limitations of this section do not apply to -
(B ) An experimental certificate, unless the operation involves carrying a passenger


However, the FAA inspector or designated airworthiness representative (DAR) who conducts the airworthiness inspection and issues the airworthiness certificate may require the pilot have the appropriate category and class pilot certificate and ratings, and would then specify that requirement in the aircraft's Operating Limitations.

Bottom line: If the appropriate category and class requirement are listed in the Operating Limitations, you must have a minimum of a private pilot certificate, a third-class medical certificate, and a multi-engine rating to fly the Cri-Cri.
This was from a few years ago, so no Basic Med, etc.

Before spending a lot of time with design or construction, it seems pretty important to find out if the DAR is likely to add the requirement for an MEL rating (or endorsement) in the Operating Limitations, and what factors would be important in his/her decision about this.
 

Vigilant1

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Looked up 61.31 there it is all the way down the whole stinking page at the very bottom. View attachment 85400
Right. But anyone operating an aircraft must comply with the aircraft's operating limitations. And if the DAR puts a requirement for an MEL rating (or endorsement) in those OLs, then the pilot of the plane needs to have that rating (or endorsement) regardless of what Section 61.31(L)(2)(B) says. The EAA's answer to a related question about this sure makes it sound like a possibility. So, I'd sure like to know in advance if a DAR is going to do that, and what factors might affect that decision.
 

BBerson

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The EAA answer is insufficient. No mention of solo endorsements.
FAR 61.109 (b) requires a person who applies for a private pilot certificate with a multiengine class rating must log 10 hours of solo flight.
So obviously a person can log solo time without a rating.
Is logging solo time prohibited in an EA-B such as an RV-12?
 

blane.c

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The EAA answer is insufficient. No mention of solo endorsements.
FAR 61.109 (b) requires a person who applies for a private pilot certificate with a multiengine class rating must log 10 hours of solo flight.
So obviously a person can log solo time without a rating.
Is logging solo time prohibited in an EA-B such as an RV-12?
"61.31 (I) 2 The rating limitations of this section DO NOT APPLY TO - …………. (B) AN EXPERIMENTAL TICKET, UNLESS THE OPERATION INVOLVES CARRYING A PASSENGER;"

DO NOT APPLY TO.

So solo experimento no problemo'
 

blane.c

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I have been looking for that little phrase for months.

It is for experimental pilots who are not multi engine rated and who fly solo and want multiple engines "the golden words"

61.31 (I) 2 (B).
 
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