E-ABs with Allison 250 motors...?

schmookeeg

schmookeeg

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Mike Brannigan
Hello,

After throwing a rod on my freshly overhauled Contisaur motor last weekend, you might imagine that I'm browsing a lot of turboprops lately. You'd be right. :D

I like the Velocity design. I like their V-twin more.

I started fantasizing about an XL with an Allison 250 behind it. Should do about as good as the TSIO-550 option I'd think, and you'd want a LOT more fuel on board the thing, but that's what experimental is for, right? Pass the sawzall.

I'm somewhat mystified that the allison 250 isn't popular in E-AB. I can't find much reference to its use anywhere. Are there any airframes that use this? I have found 0 Allisons and a smattering of Mazda wankels and subaru boxers. Surely the certified engine represents a simpler path to E-AB approval?

The TP100 Czech motor has the RV-10 install and that's a big sensation, and it burns about 50% more Jet-A than the Allison motor.

Am I overlooking some cool resource somewhere? My daydreaming needs continue. :D

Appreciate any leads.

- Mike
 
There’s an XL with a TP100 behind it. Was up for sale a couple years back.

Can’t remember any EAB using the 250. Of course there’s some C210s and BE35s out there. Problem with the 250, just like all the little turbines, is the cost and fuel burn. The old 250s have only like 317hp and I believe she burns 25 gal/hr. Unless you’ve got a lot of $$$ and are really concerned about saving weight, the I0-550s are hard to beat. Of course the sound though…;)
 
Well, allison may disappoint, but doing what you thought was right (conti...said no one ever) isn't working so hot....To quote the 40yo Virgin:
fce543bd-c21c-44e7-97db-24eae51bf2f7_text.gif


:D
 
schmookeeg said:
I'm somewhat mystified that the allison 250 isn't popular in E-AB.
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Too expensive even for the C18 models. Have seen some one off attempts but saw more installed in TC'd aircraft and boats than in E/AB aircraft. They use a Solar T62 turbine for E/AB helicopters but don't think it would it big enough for your use. Lancair uses PW PT-6 I think but major $$$$. However, there are a number of new turbines out there that are coming to market. They're mainly geared toward the sustainable/eV markets but even those maybe too small as well. Its technically Rolls Royce (Allison) now but the 250 series is still a main line engine in the helicopter side so not many really get into the E/AB side.
 
Cost and fuel consumption (due both to engine design and typical E-AB operating altitudes) are the 2 main reasons. The fact that most don’t want to roll their own firewall forward (or firewall back) engine package is a close third. Yes there have been turbine installations but they are quite rare even compared to auto conversions.
 
hindsight2020 said:
Well, allison may disappoint, but doing what you thought was right (conti...said no one ever) isn't working so hot....To quote the 40yo Virgin:
fce543bd-c21c-44e7-97db-24eae51bf2f7_text.gif


:D
Click to expand...

Are you suggesting that before throwing the contis out and heading to some bizarre turbine, I might switch to team Lycosaur first?

You're really ruining this fantasy with logic. :D 2 Aviation Demerits!
 
Doc Holliday said:
Since you are talking experimental, then go with the Allison T63 military engines.

https://www.govdeals.com/?fa=Main.Item&itemid=111&acctid=6026

Here's a B17C prop reduction gearbox to go with it. https://www.barnstormers.com/classified-1797125-B-17C-Prop-reduction-gearbox.html?catid=18315
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You're following my thought train exactly. Why buy some $50,000 Experimental WTFIO-370 Lycoming-derivative mill when you can get a proper certified turbine instead?

Apparently the E-AB crew do not follow this logic, and other than "because we're cheap" (which I have NOT found to be the case in the E-AB world) I'm trying to get my head around why.
 
schmookeeg said:
You're following my thought train exactly. Why buy some $50,000 Experimental WTFIO-370 Lycoming-derivative mill when you can get a proper certified turbine instead?

Apparently the E-AB crew do not follow this logic, and other than "because we're cheap" (which I have NOT found to be the case in the E-AB world) I'm trying to get my head around why.
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gee you’re right and we’re all idiots. Why didn’t we think of this? Tell you what, you build something, install this or any other turboprop, make it reliable and equal in terms of cost of acquisition, operation, and maintenance to the available piston engines it would replace plus have reasonable maintenance support and we’ll line up and buy it.

People have been trying to do this for decades (google Innodyn). There’s reasons why none have been successful.
 
giphy.gif

:D

*runs to kitchen* Hey the butthurt started y'all, get the corn!....
 
The military T63 is the identical engine to the C18/C20 Allison. These engines have a military data plate, and are not interchangeable with their civilian counterparts.

The T63 and it's parts can be bought reasonable, and there are still lots of them out there.
 
I remember a few years back talking to our company engine guy on RR250 costs. Said our supplier usually charges $180-200K for a used RR250. Now, that’s a C47B and way more HP (675) than the old C18s but they ain’t cheap. I can also tell you, there’s a million and one inspections on the thing. While we’re on a 135 AAIP and you wouldn’t have to meet that criteria, they ain’t cheap.
 
I don't know why my questions are being interpreted as critical of E-AB. Said more simply, "clearly E-AB are not idiots, I'm curious why this is not more common than it is, particularly in the face of other odd choices like mazda and subaru auto engines. The only reason I see on its face, and quoted here, is expense, neither of which seem to apply to this engine -- including the fuel burn, which for me where Jet-A is literally half of 100LL at my home drome"


The inspection intervals are new info to me, thanks for that. I have a path to research and see how the Silver Eagles are tolerating it.
 
I’ve given you reasons as to why— and it’s been tried for decades. Again if it was a panacea, it would have been adopted, but it’s not. I really wish it was, or if not a turbine a diesel. But diesel development has been even more problematic. I’ve been watching alternative engine development since the mid ‘90s and the landscape is littered with the corpses of companies who have great marketing brochures and tons of specs that promise the world, yet here we are still flying behind Lyc’s and Conti’s. At this rate, an electric solution will probably be the ultimate solution.
 
schmookeeg said:
I don't know why my questions are being interpreted as critical of E-AB. Said more simply, "clearly E-AB are not idiots, I'm curious why this is not more common than it is, particularly in the face of other odd choices like mazda and subaru auto engines. The only reason I see on its face, and quoted here, is expense, neither of which seem to apply to this engine -- including the fuel burn, which for me where Jet-A is literally half of 100LL at my home drome"
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There have been a couple jet powered and turboprop Velocity's. It just doesn't work. I'm guessing that the guys who have done it that were able to get past the acquisition cost figured out that after you add enough fuel tanks in the cabin, the useful load turned a 4-place into a 2-place.
 
Another problem is the 80 - 90 lbsweight difference between a 520 and a 250. Brings up cg design issues.
 
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