# Hirth 35HF Jet A 2-stroke, no oil mixing needed

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#### 12notes

##### Well-Known Member
Log Member
I stumbled across this engine recently but can't find any more info or if it's available to any organization too small to have it's own military:

It's a 2 stroke, 60 Hp, 79 lb (wet), 2 cylinder engine that runs on kerosene based fuels (Jet A) and doesn't need oil mixed into the fuel. My main objection to 2 stroke engines is the need to mix the oil with the fuel. This seems to solve that problem, it lighter than the 1/2 VW I currently have while being a lot more powerful. Apparently there was an earlier version called the 3503 HF, and I've also seen reference to the Hirth S1204 HF, which is based on the F23, and has 45hp and weighs around 50 lbs.

I was wondering if anyone has seen one, has any experience with one, or knows what they cost. Ideally, the S1204HF would work for my application if it can be found and it's not extremely expensive. 35HF would be overkill power-wise, but still fit.

Other than a potential whopper of a price, is there some downside I'm not seeing here?

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PMD

#### Hot Wings

##### Grumpy Cynic
HBA Supporter
Log Member
is there some downside I'm not seeing here?
Yes.
At only 79 pounds it will make all the work I have, and will do, to convert an industrial engine for my Quickie wasted time.
I suspect the price will be well into the 5 figures range so I'll just keep plugging along.............

#### 12notes

##### Well-Known Member
Log Member
Yes.
At only 79 pounds it will make all the work I have, and will do, to convert an industrial engine for my Quickie wasted time.
I suspect the price will be well into the 5 figures range so I'll just keep plugging along.............
The similar gasoline version, the Hirth 3503 with fuel injection, electric start, and gearbox is $12,500, the 35 HF is probably more than that. The S1204 has a chance of being under$10K.

#### Woodenwings

##### Well-Known Member
A am SERIOUSLY considering a 3502e for my project. I have quotes and suppliers. I dobt have anyone to talk to or visit to see one first hand. I like the Yamah Phazer option in theory...4stroke etc. I dont like an engine not designed for aircraft. I dont like carbs or mixing oil with gas. I dont like standing on wheels pouring fuel on wings either.

Im taking my time to decide. Would like to talk to serious folks that know engines.

#### AJLiberatore

##### Well-Known Member
I stumbled across this engine recently but can't find any more info or if it's available to any organization too small to have it's own military:

It's a 2 stroke, 60 Hp, 79 lb (wet), 2 cylinder engine that runs on kerosene based fuels (Jet A) and doesn't need oil mixed into the fuel. My main objection to 2 stroke engines is the need to mix the oil with the fuel. This seems to solve that problem, it lighter than the 1/2 VW I currently have while being a lot more powerful. Apparently there was an earlier version called the 3503 HF, and I've also seen reference to the Hirth S1204 HF, which is based on the F23, and has 45hp and weighs around 50 lbs.

I was wondering if anyone has seen one, has any experience with one, or knows what they cost. Ideally, the S1204HF would work for my application if it can be found and it's not extremely expensive. 35HF would be overkill power-wise, but still fit.

Other than a potential whopper of a price, is there some downside I'm not seeing here?
I was blessed to do an Interview and story on this engine for "Contact Magazine" over 10 yrs ago (many thanks to Matt Dandar) and got to see in person. I don't have the article/Issue info at hand. It is quite interesting and also expensive and immic for the UAV/Unmanned arena only.

#### Woodenwings

##### Well-Known Member
I was blessed to do an Interview and story on this engine for "Contact Magazine" over 10 yrs ago (many thanks to Matt Dandar) and got to see in person. I don't have the article/Issue info at hand. It is quite interesting and also expensive and immic for the UAV/Unmanned arena only.
I have a couple quotes to buy one - spendy wee things.
so far i can't find a better replacement for the original Hirth that was on the plane.

#### jedi

##### Well-Known Member
nwuav.com
11160 SW Durham Lane, Suite 1
McMinnville, Oregon USA
++1-503-770-5913
+1-503-217-6080

Mat is still around

 Recreational Power Engineering​NEW ENGINE SALES & INFORMATION: 11160 SW Durham Lane McMinnville, Oregon 97128 Phillip Yager (503) 434-6845 x 126 Email: [email protected]​SPARE PARTS SALES, ENGINE REPAIRS, & TECHNICAL SUPPORT: 5479 E. Co. Rd. 38 Tiffin, Ohio 44883 Matt Danbar (419) 585-7002 Fax: (419) 585-6004 ​

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#### Woodenwings

##### Well-Known Member
Feel like a doughnut....but have been buisy with this. Hirth in Germany have helped me with techical details. Now i have lots of 3d modelling to complete. Onto the throttles today. I have finaly decided on the engine for my project.... obviously!

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#### ToddK

##### Well-Known Member
HBA Supporter
Wow. Got to let us know what it cost.

The doughnut?

#### jedi

##### Well-Known Member
Which engine? What is project? Is engine in hand? When will it fly?

#### Woodenwings

##### Well-Known Member
Engine not in hand. Hirth 3503ev. Spendy thing that has a warranty that starts when i purchase it. So......planning ahead of that with solidworks. Lots of work to do...and regular life to enjoy too. Plane was an Hornet Ultralight....now becoming an experimental after teardown and rebuild with modds.
5yr. Plan. Will post more as it develops!
No rush.

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